ML16091A005

Draft STP RAI Applicability Matrix for Review of GSI-191

ML16091A005
Person / Time
Site:	South Texas
Issue date:	03/01/2016
From:	Harrison A South Texas
To:	Lisa Regner Plant Licensing Branch IV
References
MF2400, MF2401
Download: ML16091A005 (396)

Text

1 NRR-PMDAPEm Resource From:Harrison Albon <awharrison@STPEGS.COM>

Sent: Tuesday, March 01, 2016 8:46 PM To: Regner, Lisa Cc: Kee, Ernie; Blossom, Steven

Engen, Rob; Richards, Drew

Subject:

[External_Sender] STP GSI-191 RAI Cross Reference Attachments:

RAI Response Cross Reference.pdf Lisa, Here is the link to our DRAFT RAI cross-reference that we discussed in the public call on 2/18. We would like to discuss this at the staff's earliest convenience and follow that up with a docketed submittal. Note that the document is fairly easily navigated using the internal links.

https://stpegs.sharefile.com/d-scce1a0b0cdd4d1ca

Regards, Wayne Harrison

Hearing Identifier: NRR_PMDA Email Number: 2747 Mail Envelope Properties (A47D93CA-E20C-424E-8C78-673C44706144)

Subject:

[External_Sender] STP GSI-191 RAI Cross Reference Sent Date: 3/1/2016 8:46:25 PM Received Date: 3/1/2016 8:45:26 PM From: Harrison Albon Created By: awharrison@STPEGS.COM Recipients: "Kee, Ernie" <keeej@STPEGS.COM>

Tracking Status: None "Blossom, Steven" <sdblossom@STPEGS.COM>

Tracking Status: None "Engen, Rob" <rlengen@STPEGS.COM> Tracking Status: None "Richards, Drew" <amrichards@STPEGS.COM> Tracking Status: None "Regner, Lisa" <Lisa.Regner@nrc.gov>

Tracking Status: None Post Office: stpegs.com

Files Size Date & Time MESSAGE 374 3/1/2016 8:45:26 PM RAI Response Cross Reference.pdf 18583031 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

DRAFTNRCReviewoftheSTPNOCLAR withResponsesTuesday1 stMarch,2016:19:32 DRAFTContents1NRCRequestsforAdditionalInformation181.1CrossreferencingRAIstoresponses................181.2RoverDimpacts............................18 1.3Round1RAIs............................341.3.1APLAB............................341.3.1.1CASAGRANDE.................341.3.1.2RESULTSINTERPRETATION.........451.3.2ACRB.............................481.3.3EMCB.............................501.3.4EPNB.............................511.3.5ESGB.............................531.3.5.1Chemical..................531.3.5.2Coatings......................591.3.6SCVB.............................611.3.7SNPB.............................641.3.8SRXB.............................651.3.9SSIB..............................661.3.10STSB.............................811.4Round2RAIs............................831.4.1APLAB............................831.4.2EMCB.............................881.4.3ESGB.............................891.4.4SCVB.............................941.4.5SNPB.............................1011.4.6SSIB..............................1031.4.7STSB.............................1112RAIResponses(Round1)1142.1ML14149A434,Firstsetofresponses................1142.1.1APLABResponses......................1142.1.1.1APLAB,CASAGrande,LOCAFrequencies:Ques-tion1........................1142.1.1.2APLAB,CASAGrande,LOCAFrequencies:Ques-tion3........................1152.1.1.3APLAB,CASAGrande,LOCAFrequencies:Ques-tion4........................1162.1.1.4APLAB,CASAGrande,toPRAInterface-Gen-eral:Question1a..................116 1

DRAFT CONTENTS2.1.1.5APLAB,CASAGrande,toPRAInterface-Gen-eral:Question1b..................1162.1.1.6APLAB,CASAGrande,toPRAInterface-Gen-eral:Question3..................1172.1.1.7APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4a..................1172.1.1.8APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4b..................1182.1.1.9APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4c..................1182.1.1.10APLAB,CASAGrande,toPRAInterface-Gen-eral:Question5..................1192.1.1.11APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6a..................1192.1.1.12APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6b..................1192.1.1.13APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6c..................1202.1.1.14APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1................1202.1.1.15APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2................1212.1.1.16APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4a...............1212.1.1.17APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4b...............1222.1.1.18APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6................1242.1.1.19APLAB,STPPRAModel-PRAScope:Ques-tion1........................1252.1.1.20APLAB,ResultsInterpretation-Quanti"cation:Question1a.....................1262.1.1.21APLAB,ResultsInterpretation-Quanti"cation:Question1b....................1262.1.1.22APLAB,ResultsInterpretation-Quanti"cation:Question2.....................1262.1.1.23APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question2..................1562.1.2ESGBResponses.......................1572.1.2.1ESGB,ChemicalQuestion12......1572.1.2.2ESGB,ChemicalQuestion13a.....1582.1.2.3ESGB,ChemicalQuestion13b.....1592.1.2.4ESGB,ChemicalQuestion13c.....1592.1.2.5ESGB,ChemicalQuestion19......1612.1.3SRXBResponses.......................1612.1.3.1SRXB,Question1.................1612.1.3.2SRXB,Question2.................1612.1.3.3SRXB,Question3.................161Tuesday1 stMarch,2016:19:32,Page2of393 DRAFT CONTENTS2.1.3.4SRXB,Question4.................1612.1.3.5SRXB,Question5a................1612.1.3.6SRXB,Question5b................1622.1.3.7SRXB,Question5c................1622.1.3.8SRXB,Question6.................1632.1.3.9SRXB,Question7a................1632.1.3.10SRXB,Question7b................1632.1.3.11SRXB,Question8.................1642.1.3.12SRXB,Question9.................1642.1.4SSIBResponses........................1662.1.4.1SSIB,ZOI:Question1...............1662.1.4.2SSIB,DebrisCharacteristics:Question2....1662.1.4.3SSIB,Transport:Question5...........1662.1.4.4SSIB,Transport:Question9...........1672.1.4.5SSIB,Transport:Question11a..........1672.1.4.6SSIB,Transport:Question11b..........1672.1.4.7SSIB,Transport:Question11c..........1682.1.4.8SSIB,Transport:Question11d..........1682.1.4.9SSIB,Transport:Question11e..........1682.1.4.10SSIB,Transport:Question13...........1692.1.4.11SSIB,NPSHandDegasi"cation:Question29..1772.1.5STSBResponses.......................1772.1.5.1STSB:Question1.................1772.1.5.2STSB:Question2.................1782.1.5.3STSB:Question3.................1792.2ML14178A481,Secondsetofresponses...............1802.2.1APLABResponses......................1802.2.1.1APLAB,CASAGrande-LOCAFrequencies:Question2.....................1802.2.1.2APLAB,STPPRAModel-General:Question2180 2.2.1.3APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5................1802.2.2ESGBResponses.......................1812.2.2.1ESGB,ChemicalQuestion3.......1812.2.2.2ESGB,ChemicalQuestion7.......1822.2.2.3ESGB,ChemicalQuestion11a.....1862.2.2.4ESGB,ChemicalQuestion11b.....1862.2.2.5ESGB,ChemicalQuestion17......1872.2.2.6ESGB,ChemicalQuestion20......1882.2.2.7ESGB,ChemicalQuestion22a.....1892.2.2.8ESGB,ChemicalQuestion22b.....1912.2.3SCVBResponses.......................1922.2.3.1SCVB,Question:1a................1922.2.3.2SCVB,Question:1b................1922.2.3.3SCVB,Question:2a................1922.2.3.4SCVB,Question:2b................1922.2.3.5SCVB,Question:3a................1932.2.3.6SCVB,Question:3b................193Tuesday1 stMarch,2016:19:32,Page3of393 DRAFT CONTENTS2.2.3.7SCVB,Question:3c................1962.2.3.8SCVB,Question:4a................1962.2.3.9SCVB,Question:4b................1972.2.3.10SCVB,Question:4c................1972.2.3.11SCVB,Question:5................1972.2.3.12SCVB,Question:6................1972.2.3.13SCVB,Question:7................1972.2.3.14SCVB,Question:8................1982.2.3.15SCVB,Question:9a................1982.2.3.16SCVB,Question:9b................1992.2.4SNPBResponses.......................1992.2.4.1SNPB,Question:1a................1992.2.4.2SNPB,Question:1b................2012.2.4.3SNPB,Question:1c................2032.2.4.4SNPB,Question:1d................2032.2.4.5SNPB,Question:1e................2032.2.4.6SNPB,Question:1f................2052.2.4.7SNPB,Question:1g................2052.2.4.8SNPB,Question:1h................2052.2.4.9SNPB,Question:1i................2052.2.4.10SNPB,Question:1j................2052.2.4.11SNPB,Question:1k................2072.2.4.12SNPB,Question:1l................2072.2.4.13SNPB,Question:1m...............2072.2.4.14SNPB,Question:2a................2082.2.4.15SNPB,Question:2b................2082.2.4.16SNPB,Question:2c................2082.2.4.17SNPB,Question:2d................2082.2.4.18SNPB,Question:3.................2092.2.4.19SNPB,Question:5.................2102.2.5SSIBResponses........................2112.2.5.1SSIB,Transport:Question12...........2112.2.5.2SSIB,HeadLossandChemicalBump-up:Question25a....................2112.2.5.3SSIB,HeadLossandChemicalBump-up:Question25b....................2122.2.5.4SSIB,HeadLossandChemicalBump-up:Question26a....................2122.2.5.5SSIB,HeadLossandChemicalBump-up:Question26b....................2122.2.5.6SSIB,HeadLossandChemicalBump-up:Question26c....................2122.2.5.7SSIB,HeadLossandChemicalBump-up:Question26d....................2132.2.5.8SSIB,HeadLossandChemicalBump-up:Question26e....................2152.2.5.9SSIB,HeadLossandChemicalBump-up:Question26f....................217Tuesday1 stMarch,2016:19:32,Page4of393 DRAFT CONTENTS2.2.5.10SSIB,NPSHandDegasi"cation:Question30..2172.2.5.11SSIB,NPSHandDegasi"cation:Question31..217 2.2.5.12SSIB,NPSHandDegasi"cation:Question32..217 2.2.5.13SSIB,NPSHandDegasi"cation:Question34..218 2.2.5.14SSIB,NPSHandDegasi"cation:Question35..218 2.2.5.15SSIB,In-VesselandBoricAcidPrecipitation:Ques-tion37.......................2182.2.5.16SSIB,DebrisBypass:Question39a.......2192.2.5.17SSIB,DebrisBypass:Question39b.......2212.2.5.18SSIB,DebrisBypass:Question39c........2212.2.5.19SSIB,DebrisBypass:Question39d.......2222.2.5.20SSIB,DebrisBypass:Question39e........2222.2.5.21SSIB,DebrisBypass:Question39f........2222.2.5.22SSIB,DefenseinDepthandMitigativeMeasures:Question41a....................2232.2.5.23SSIB,DefenseinDepthandMitigativeMeasures:Question41b....................2242.2.5.24SSIB,DefenseinDepthandMitigativeMeasures:Question41c....................2242.2.5.25SSIB,DefenseinDepthandMitigativeMeasures:Question41d....................2242.3ML14202A045,Thirdsetofresponses...............2242.3.1APLABResponses......................2242.3.1.1APLAB,CASAGrande-General:Question1a224 2.3.1.2APLAB,CASAGrande-General:Question1b235 2.3.1.3APLAB,CASAGrande-General:Question1c235 2.3.1.4APLAB,CASAGrande-PlantCon"guration:Question1a.....................2352.3.1.5APLAB,CASAGrande-PlantCon"guration:Question1b....................2352.3.1.6APLAB,CASAGrande-PlantCon"guration:Question2a.....................2362.3.1.7APLAB,CASAGrande-PlantCon"guration:Question2b....................2362.3.1.8APLAB,CASAGrande-PlantCon"guration:Question3a.....................2372.3.1.9APLAB,CASAGrande-PlantCon"guration:Question3b....................2382.3.1.10APLAB,CASAGrande-PlantCon"guration:Question3c.....................2382.3.1.11APLAB,CASAGrandetoPRAInterface-General:Question2a.....................2382.3.1.12APLAB,CASAGrandetoPRAInterface-General:Question2b....................2382.3.1.13APLAB,STPPRAModel-General:Question1.240 2.3.1.14APLAB,STPPRAModel-General:Question3.240 2.3.1.15APLAB,STPPRAModel-SuccessCriteria:Ques-tion1........................241Tuesday1 stMarch,2016:19:32,Page5of393 DRAFT CONTENTS2.3.1.16APLAB,STPPRAModel-SuccessCriteria:Ques-tion2a.......................2422.3.1.17APLAB,STPPRAModel-SuccessCriteria:Ques-tion2b.......................2422.3.1.18APLAB,STPPRAModel-SuccessCriteria:Ques-tion2c.......................2422.3.1.19APLAB,STPPRAModel-SuccessCriteria:Ques-tion3a.......................2432.3.1.20APLAB,STPPRAModel-SuccessCriteria:Ques-tion3b.......................2442.3.1.21APLAB,STPPRAModel-SuccessCriteria:Ques-tion3c.......................2442.3.1.22APLAB,STPPRAModel-SuccessCriteria:Ques-tion3d.......................2452.3.1.23APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3a..................2452.3.1.24APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3b..................2452.3.1.25APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3c..................2462.3.1.26APLAB,STPPRAModel-PRAScope:Question2246 2.3.1.27APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1a..................2462.3.1.28APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1b..................2462.3.1.29APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1c..................2472.3.1.30APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question3..................2472.3.1.31APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4a..................2482.3.1.32APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4b..................2482.3.1.33APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4c..................2492.3.1.34APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4d..................2492.3.1.35APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question5..................2492.3.1.36APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question6..................2492.3.2ACRBResponses.......................2512.3.2.1ARCB:Question1.................2512.3.2.2ARCB:Question2.................2512.3.2.3ARCB:Question3.................2512.3.3EMCBResponses......................2512.3.3.1ECMB,Question1................2512.3.3.2EMCB,Question2................252Tuesday1 stMarch,2016:19:32,Page6of393 DRAFT CONTENTS2.3.4ENPBResponses.......................2522.3.4.1ENPB,Question1.................2522.3.4.2ENPB,Question2.................2532.3.4.3ENPB,Question3.................2532.3.4.4ENPB,Question4.................2542.3.4.5ENPB,Question5.................2542.3.4.6ENPB,Question6a................2552.3.4.7ENPB,Question6b................2552.3.5ESGBResponses.......................2562.3.5.1ESGB,ChemicalQuestion1a......2562.3.5.2ESGB,ChemicalQuestion1b......2572.3.5.3ESGB,ChemicalQuestion1c......2572.3.5.4ESGB,ChemicalQuestion1d......2592.3.5.5ESGB,ChemicalQuestion2.......2602.3.5.6ESGB,ChemicalQuestion4.......2612.3.5.7ESGB,ChemicalQuestion5.......2612.3.5.8ESGB,ChemicalQuestion6.......2642.3.5.9ESGB,ChemicalQuestion8.......2652.3.5.10ESGB,ChemicalQuestion9.......2652.3.5.11ESGB,ChemicalQuestion10......2662.3.5.12ESGB,ChemicalQuestion14a.....2682.3.5.13ESGB,ChemicalQuestion14b.....2682.3.5.14ESGB,ChemicalQuestion14c.....2702.3.5.15ESGB,ChemicalQuestion15......2702.3.5.16ESGB,ChemicalQuestion16......2712.3.5.17ESGB,ChemicalQuestion18a.....2722.3.5.18ESGB,ChemicalQuestion18b.....2722.3.5.19ESGB,ChemicalQuestion18c.....2722.3.5.20ESGB,ChemicalQuestion21......2732.3.5.21ESGB,Coatings:Question1...........2732.3.5.22ESGB,Coatings:Question2...........2742.3.5.23ESGB,Coatings:Question3...........2742.3.5.24ESGB,Coatings:Question4...........2742.3.5.25ESGB,Coatings:Question5...........2772.3.5.26ESGB,Coatings:Question6a..........2802.3.5.27ESGB,Coatings:Question6b..........2802.3.5.28ESGB,Coatings:Question6c...........2802.3.5.29ESGB,Coatings:Question7...........2812.3.5.30SNPB,Question4.................2832.3.6SSIBResponses........................2852.3.6.1SSIB,DebrisCharacteristics:Question3....2852.3.6.2SSIB,Transport:Question4...........2852.3.6.3SSIB,Transport:Question6a...........2882.3.6.4SSIB,Transport:Question6b..........2882.3.6.5SSIB,Transport:Question6c...........2902.3.6.6SSIB,Transport:Question6d..........2932.3.6.7SSIB,Transport:Question6e...........2972.3.6.8SSIB,Transport:Question7a...........301Tuesday1 stMarch,2016:19:32,Page7of393 DRAFT CONTENTS2.3.6.9SSIB,Transport:Question7b..........3022.3.6.10SSIB,Transport:Question7c...........3032.3.6.11SSIB,Transport:Question7d..........3032.3.6.12SSIB,Transport:Question7e...........3042.3.6.13SSIB,Transport:Question7f...........3042.3.6.14SSIB,Transport:Question8a...........3042.3.6.15SSIB,Transport:Question8b..........3052.3.6.16SSIB,Transport:Question8c...........3052.3.6.17SSIB,Transport:Question8d..........3052.3.6.18SSIB,Transport:Question8e...........3052.3.6.19SSIB,Transport:Question10...........3052.3.6.20SSIB,HeadLossandChemicalBumpUp:Question14..................3062.3.6.21SSIB,HeadLossandChemicalBumpUp:Question15a.................3072.3.6.22SSIB,HeadLossandChemicalBumpUp:Question15b.................3072.3.6.23SSIB,HeadLossandChemicalBumpUp:Question15c.................3072.3.6.24SSIB,HeadLossandChemicalBumpUp:Question15d.................3092.3.6.25SSIB,HeadLossandChemicalBumpUp:Question16a.................3102.3.6.26SSIB,HeadLossandChemicalBumpUp:Question16b.................3112.3.6.27SSIB,HeadLossandChemicalBumpUp:Question16c.................3122.3.6.28SSIB,HeadLossandChemicalBumpUp:Question16d.................3122.3.6.29SSIB,HeadLossandChemicalBumpUp:Question17a.................3132.3.6.30SSIB,HeadLossandChemicalBumpUp:Question17b.................3142.3.6.31SSIB,HeadLossandChemicalBumpUp:Question17c.................3142.3.6.32SSIB,HeadLossandChemicalBumpUp:Question17d.................3142.3.6.33SSIB,HeadLossandChemicalBumpUp:Question17e.................3142.3.6.34SSIB,HeadLossandChemicalBumpUp:Question17f..................3152.3.6.35SSIB,HeadLossandChemicalBumpUp:Question18a.................3152.3.6.36SSIB,HeadLossandChemicalBumpUp:Question18b.................3152.3.6.37SSIB,HeadLossandChemicalBumpUp:Question18c.................316Tuesday1 stMarch,2016:19:32,Page8of393 DRAFT CONTENTS2.3.6.38SSIB,HeadLossandChemicalBumpUp:Question18d.................3172.3.6.39SSIB,HeadLossandChemicalBumpUp:Question18e.................3172.3.6.40SSIB,HeadLossandChemicalBumpUp:Question19..................3172.3.6.41SSIB,HeadLossandChemicalBumpUp:Question20..................3182.3.6.42SSIB,HeadLossandChemicalBumpUp:Question21a.................3192.3.6.43SSIB,HeadLossandChemicalBumpUp:Question21b.................3192.3.6.44SSIB,HeadLossandChemicalBumpUp:Question21c.................3192.3.6.45SSIB,HeadLossandChemicalBumpUp:Question21d.................3202.3.6.46SSIB,HeadLossandChemicalBumpUp:Question22..................3202.3.6.47SSIB,HeadLossandChemicalBumpUp:Question23..................3212.3.6.48SSIB,HeadLossandChemicalBumpUp:Question24..................3212.3.6.49SSIB,HeadLossandChemicalBumpUp:Question27..................3232.3.6.50SSIB,HeadLossandChemicalBumpUp:Question28..................3232.3.6.51SSIB,NPSHandDegasi"cation:Question33..324 2.3.6.52SSIB,NPSHandDegasi"cation:Question36..325 2.3.6.53SSIB,NPSHandDegasi"cation:Question38..327 2.3.6.54SSIB,DefenseInDepthandMitigativeMeasures:Question40.....................3272.3.6.55SSIB,DefenseInDepthandMitigativeMeasures:Question42.....................3293ResponsetoEPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6330 3.1EPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6.................................3303.2ConsistencyofLOCAFrequencyEstimates:GSI-191SubmittalandRI-ISI...............................3313.3EstimateofCDF..........................3313.4FrequenciesofSmall,Medium,andLargeBreaks.........3323.5ProbabilityDistributionsGoverningBreakSizeandWeldCase.3324RAIResponses(Round2)3374.1ML15091A440,APLABResponses.................3374.1.1Question1:ProjectQualityAssurance...........3374.1.2Question2:ProjectQualityAssurance...........337Tuesday1 stMarch,2016:19:32,Page9of393 DRAFT CONTENTS4.1.3Question3:ProjectQualityAssurance...........3384.1.4Question4:ProjectQualityAssurance...........3384.1.5Question1:TreatmentofUnanalyzedPlantConditions.344 4.1.6Question7:HumanReliabilityAnalysis..........3444.1.7Question1:KeyAssumptions/KeySourcesofUncertainty344 4.1.8Question1:ValidityofAssumptiononPumpCon"gurations345 4.1.9Question7:CASAGrandetoPRAInterface.......3454.1.10Question1:FidelitybetweenRELAPSimulationsandCASAGrande............................3454.1.11Question1:State-of-KnowledgeCorrelation........3464.1.12Question1:SelectionofJohnsonParameters.......3464.2ML15091A440,EMCBResponses..................3464.2.1Question2..........................3464.3ML15091A440,ESGBResponses..................3464.3.1Question23:Chemical...............3464.3.2Question24:Chemical...............3474.3.3Question25:Chemical...............3474.3.4Question26:Chemical...............3474.3.5Question27:Chemical...............3474.3.6[ML15091A440]Question28:Chemical......3474.3.7Question29:Chemical...............3484.3.8Question30:Chemical...............3484.3.9Question31:Chemical...............3484.3.10Question32:Chemical...............3484.3.11Question33:Chemical...............3484.3.12Question34:Chemical...............3494.3.13Question8:Coatings.....................3504.3.14Question9:Coatings.....................3504.3.15Question10:Coatings....................3504.4ML15091A440,SCVBResponses..................3504.4.1Question10..........................3504.4.2ML15246A128,Question11.................3534.4.3ML15246A128,Question12(1)...............3534.4.4ML15246A128,Question12(2)...............3544.4.5ML15246A128,Question12(3)...............3544.4.6ML15246A128,Question12(4)...............3544.4.7ML15246A128,Question12(4)a...............3544.4.8ML15246A128,Question12(4)b...............3544.4.9ML15246A128,Question13.................3554.4.10ML15246A128,Question14(1)...............3554.4.11ML15246A128,Question14(2)...............3554.4.12ML15246A128,Question14(3)...............3554.4.13ML15246A128,Question14(4)...............3554.4.14ML15246A128,Question14(5)...............3554.4.15ML15246A128,Question14(5)(a)..............3554.4.16ML15246A128,Question14(5)(b)..............3564.4.17ML15246A128,Question15.................3564.4.18ML15246A128,Question16(1)...............356Tuesday1 stMarch,2016:19:32,Page10of393 DRAFT CONTENTS4.4.19ML15246A128,Question16(2)...............3564.4.20ML15246A128,Question16(3)...............3564.4.21ML15246A128,Question16(4)...............3564.4.22ML15246A128,Question16(5)...............3574.4.23ML15246A128,Question16(5)(a)..............3574.4.24ML15246A128,Question16(5)(b)..............3574.4.25ML15246A128,Question17.................3574.4.26ML15246A128,Question18(a)(b)(c)(d).........3574.5ML15091A440,SNPBResponses..................3574.5.1Question6..........................3574.5.2Question7..........................3584.5.3Question8..........................3584.5.4Question9..........................3584.5.5Question10..........................3584.6ML15091A440,SSIBResponses...................3584.6.1Question43..........................3584.6.2Question44..........................3594.6.3Question45..........................3644.6.4Question46..........................3674.6.5Question47..........................3684.6.6Question48..........................3684.6.7Question49..........................3694.6.8Question50..........................3694.6.9Question51..........................3694.6.10Question52..........................3704.6.11Question53..........................3704.6.12Question54..........................3714.6.13Question55..........................3724.6.14Question55a.........................3724.6.15Question56..........................3724.6.16Question57(a)........................3724.6.17Question57(b)........................3724.6.18Question57(c)........................3724.6.19Question57(d)........................3734.6.20Question57(e)........................3734.6.21Question57(f)........................3744.6.22Question58..........................3744.6.23Question59..........................3754.6.24Question60..........................3824.6.25Question61..........................3834.6.26Question62..........................3854.6.27Question63..........................3854.6.28Question64..........................3854.6.29Question65..........................3854.6.30Question66..........................3864.7ML15091A440,STSBResponses..................3864.7.1Question4..........................386Tuesday1 stMarch,2016:19:32,Page11of393 DRAFT CONTENTS AFWAuxiliaryFeedWater BAPBoricAcidPrecipitation BAPBoricAcidPrecipitation BBCoreBarrelBypass BWRBoilingWaterReactor CADComputerAidedDesign CASAContainmentAccidentStochasticAnalysis(CASA)Grande CCFLCounterCurrentFlowLimit CCWComponentCoolingWaterSystem CDFCoreDamageFrequency CFDComputational"uiddynamicsCDFChangeincoredamagefrequencyaboveabaselinelevelLERFChangeinlargeearlyreleasefrequencyaboveabaselinelevel CHRSContainmentHeatRemovalSystemisaengineeredsafetysystemtoremovedecayheatloadfromthecontainmentafterreactor shutdown cdfCumulativeDistributionFunction:

F (x)=xf (t)dt,where f (*)isthepdf CLBColdLegBreak CSSContainmentSpraySystem DEGBDouble-EndedGuillotineBreak DID Defense-in-Depth ECWEssentialCoolingWaterSystem EOPsEmergencyOperatingProcedures ECCSEmergencyCoreCoolingSystem EOPEmergencyOperatingProcedures ESDEventSequenceDiagram FAFuelAssembly.Severalfuelassembliesareloadedinthereactorvesseltoformthereactorcore FAFuelAssemblyTuesday1 stMarch,2016:19:32,Page12of393 DRAFT CONTENTS FIDOEFIberOperationsEngine;applicationthatsolves"bermassconservation FiDOEFiberOperationsEngine GDCGeneralDesignCriteria(AppendixAtoPart50ofthecodeoffederalregulations)GL2004-02NRCGenericLetter2004-02 GRAGenerationRiskAssessment GSI-191GenericSafetyIssue191-theNRCGenericSafetyIssuenumber 191 GSI-191GenericSafetyIssue191 HHSIHighHeadSafetyInjection HLBHotLegBreak HLSOHotLegSwitchOver HRAHumanReliabilityAnalysis IOZInorganiczinc INLIdahoNationalLaboratory ISIASMESectionXIInserviceInspectionisanASMESectionXIprogramthat,amongotherthings,veri"estheweldintegrityin criticalpiping LARLicenseAmendmentRequest LANLocalAreaNetwork LBLicensingBasisisthecollectionofcommitmentsandrequirementsthatlicenseemakestotheregulatoryauthority(in thiscase,theNRC)overthecourseoftime LBBLeakbeforebreakisaproposedlicensingapproachthatreliesontheobservationthatpriortoacatastrophicfailureinlargebore piping,asmall,detectable"owinitiatesLDFGLowDensityFiberglass(suchasNUKON TM)LERLicenseeEventReport LERFLargeEarlyReleaseFrequency LHSLatinHypercubeSamplingisasimulation-basedprocedurethatgeneralizesthenotionofstrati"edsamplingtomultiple dimensionsandyieldsanunbiasedpointestimate,while attemptingtoreducevarianceoftheestimatorovernaiveMonte CarlosamplingTuesday1 stMarch,2016:19:32,Page13of393 DRAFT CONTENTS LHSILowHeadSafetyInjection LLOCALargeBreakLossofCoolantAccident LOCALossofCoolantAccident LOSPLossofPower LLRFLargeLateReleaseFrequencyLWRLightWaterReactor MFWMainFeedWater MLOCAMediumBreakLossofCoolantAccident NLHSNonuniformLatinHypercubeSamplingisavariantoftheLHSschemethatallowsthesupportofeachmarginaldistributionto bepartitionedintocellswithnon-equalprobabilities NPSHNetPositiveSuctionHead NOPNormalOperatingPressure NOTNormalOperatingTemperature NPSHANetPositiveSuctionHeadAvailable NPSHRNetPositiveSuctionHeadRequiredNPSHmargin (*)Thetime-dependentNPSHmargin;i.e.,thedbetweentheNPSHavailableandtheNPSHrequiredNRCTheNuclearRegulatoryCommission NSSSNuclearSteamSupplySystemisthenuclearreactor,piping,pumps,steamgenerators,pressurizer,andauxiliaryequipment associatedwithoperationandcontrolofthereactorsystem NSSSNuclearSteamSupplySystempdfAprobabilitydensityfunctionspeci"estherelativelikelihoodthatacontinuousrandomvariabletakesonaspeci"cvalue.

Whenintegratedoveraregion,representinganevent,thepdf yieldstheprobabilitymassassociatedwiththeevent,asinthe probabilityofobservingabreakdiameterbetween2-inchesand 5-inches PHSAProbabilisticSeismicHazardAnalysisistheprobabilisticstudyofseismiceventsonsystems,structures,andcomponentsto obtainfailurelikelihoods PCTPeakCladdingTemperature PNGPortableNetworkGraphicsTuesday1 stMarch,2016:19:32,Page14of393 DRAFT CONTENTS PRAProbabilisticRiskAssessment PWRPressurizedWaterReactorPWROGPressurizedWaterReactorOwnersGroup PWSCCPrimaryWaterStressCorrosionCracking RBDReliabilityBlockDiagram RBMKHighPowerChannel-typeReactorRCBReactorContainmentBuildingRCFCTheReactorContainmentFanCoolersRCPReactorCoolantPumpRCSReactorCoolantSystemRG1.174RegulatoryGuide1.174isaregulatoryguidancedocumentthatdescribestheoverallmethodologytoquantifyriskusingthePRA togetherwithdeterministically-basedcriteriatoevaluatethe acceptabilityofaparticularchange.Thequantitativerisk measuresareCDFandLERF.Theriskisdeemedtobevery smallwhenthechangeincreasesCDFlessthan10 6andtheLERFlessthan10 7 RHRResidualHeatRemovalSystem RMIRe"ectiveMetalInsulationisa"tted,rigidinsulationthatusesmetalradiationheatshieldsanddeadairspacetoreduceheat

loss RMSRecordsManagementSystemistheSTPNOCdocumentstorageandretrievalsystemmeetingtherequirementsofRegulatory Guide1.33,Revision2,QualityAssuranceProgram Requirements(Operation)

RMTSRiskManagedTechnicalSpeci"cationstheallowedoutagetimeforrisksigni"cantequipmentderivedfromthecon"gurationrisk duringtheoutagetimeRoverDRisk-informedOverDeterministicRUFFRiskUncertaintyFrequencyFunction.TheapplicationforinterpolatingNUREG1829frequencies RVReactorvesselandreactorcoreRWSTRefuelingWaterStorageTank RYReactorYear SISafetyInjectionSystemTuesday1 stMarch,2016:19:32,Page15of393 DRAFT CONTENTS SGSteamGenerator SLOCASmallBreakLossofCoolantAccident STPSouthTexasProject STLstereolithography"leformat STPNOCTheSTPNuclearOperatingCompany TSPTrisodiumphosphate(NA 3 PO 4*12H 2O)sumpwaterpHchemical ZOIZoneofIn"uence DbreakLOCAbreakdiameter D iThebreaksizeatanyparticularlocation(locationsindexedby i=1 , 2 ,...,N)Dsmall icorrespondstothesmallestbreaksizeatanyparticularlocationthatproducesmore"nesintheECCSsumpthanthetested amount D pipePipediameter F DbreaklweldcaseIstheconditionaldistributiongoverningtherandombreak diameter, Dbreak,giventhatabreakoccursataspeci"edweldtype/case f iFrequencyassociatedwiththebreakdiameter, D i fsmallest iFrequencyassociatedwiththebreakdiameter, D i H (*)ThefunctionbasedonNUREG-6224usedincomputingheadlossacrossECCSsumpstrainer kTheindex, k=1 , 2 ,...,K,forbreakssampledataparticularlocation(i)Isthescenario-dependentazimuthalangleofthebreakaroundthepipech (*)Isthetime-andscenario-dependentchemicalbump-upfactorusedincomputingheadlossacrossECCSsumpstrainerThefractionoftotaltime-dependentECCS"ow(Q(t))thatpassesthroughtrainsECCSstrainerandarrivesintheRCS.Theindex=A,B,Creferstotheassociatedtrain w iWeightassociatedwithascenariointherisk-informedcategory UQUncertaintyQuanti"cation LHSLatinHypercubeSamplingTuesday1 stMarch,2016:19:32,Page16of393 DRAFT CONTENTS LPLowerPlenum IEInitiatingEvent DEGBDoubleEndedGuillotineBreak ZOIZoneOfIn"uence CFPConditionalFailureProbabilityTuesday1 stMarch,2016:19:32,Page17of393 DRAFTPart1NRCRequestsforAdditionalInformationThereweretworoundsofquestionsontheLAR.Approximately259individualquestionswereinthe"rstroundandabout90individualquestionsinthesecond round.TheRoverDmethodologygreatlyreducedtheworkrequiredtoanswer theRAIs.ManyoftheRAIresponsesrefertoRoverD.WhereRoverDhaspre-emptedthequestion,thisisnotedintheleftmargin,forexample,RoverD deletes.Otherwise,wehavenotedwhereaquestionstillapplieswithaleftmarginnotesuchasRoverDrequired

.1.1CrossreferencingRAIstoresponsesWecross-referencedtheRAIresponsestothequestions.Thecrossreferencesarelinkedtotheanswersinthemargins(forexample,Response,Pg.223).

Theresponsesarelikewisecrossreferencedtotherespectivequestion.There-sponsesareorganizedintwomajorsections,Round1RAIsandRound2RAIs.

TheRound1responsesarealsogroupedaccordingthethreesets(FirstSet, SecondSet,andThirdSet)withtheexceptionoftheonesansweredinthe AugustLARsupplement.ThosearegroupedwiththeRound2responses.TheRAIsareintwosections,the"rstroundandthesecondround.WitheachRAI,theresponseiscross-referencedwithmarginnotesasdescribedabove.1.2RoverDimpactsTheRoverDmethodologyisdesignedtoreducetheamountofworkrequiredto developandreviewthebasisformakingdecisionsregardingtheriskassociated withdebrisincontainment.OverthethreeyearssincetheJanuary2013submit-taloftheSTPLAR,manyquestionswereraisedconcerningtherelativelynew andinnovativemethodologythatusedUQtoobtainconditionalfailureprob-abilitiesthatwereinturn,usedintheProbabilisticRiskAssessment(PRA)to computethemetrics,CDF,Changeincoredamagefrequencyaboveabaseline level(,LargeEarlyReleaseFrequency(LERF),andChangeinlarge earlyreleasefrequencyaboveabaselinelevelInhere,thecollectedquestionsraisedbytheTheNuclearRegulatoryCom-mission(NRC)inthecourseofreviewaresummarizedalongwithresponses.In SeveralofthequestionsandresponsesarenolongerrelevanttotheRoverD-based LAR.Inherewesummarizewhatquestionsandresponsesrelatedtothe2013 versionoftheLARtheRoverDmethodologyremovesfromreviewscopeandad-ditionalsupport.Thefollowinglistprovidesdetaileddescriptionsofcomments (primarilythoserelatedtoRemoved)toitemsusedintheBasissummarycolumninTable1.1.

18 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.ParametricdistributionsTheUQprocessrequirescharacterizationofparameterdistributionsusedinsamplingstrategiesforestimatingandpropagatingphysicalmodelre-sponses.RoverDinsteadusesatestdesignedtoboundtheuncertainty associatedwithEmergencyCoreCoolingSystem(ECCS)strainerhead

losses.2.Thermal-hydraulicsimulations(a)InordertocomprehensivelyestimatetheReactorContainmentBuild-ing(RCB)andReactorCoolantSystem(RCS)responsestod entbreakscenariosandplantstates(pumpingcombinations),several thermal-hydraulicsimulationsarerequiredtoestimatethetempera-tureandpressurehistoriesintheRCBandRCSusingcoupledmod-elsoftheRCBandRCS.RoverDreliesontheexistingTheSTP NuclearOperatingCompany(STPNOC)license-basisRCBanalysis forstrainerperformanceparameters;boundingtestdataandbound-ingthermal-hydraulicanalysistoensureadequatecorecooling.The pumpstatesareboundedfor"berpenetrationandcollection(single trainandtwoormoretrainsconsidered).(b)IntheSouthTexasProject(STP)2013LAR,considerationwasre-quiredforvariousscenariosthatwouldrepresentthepossibilitythat boricacidprecipitatescouldblockadequatecore"ow.TheRoverD methodologyreliesonsensitivitiesshowingthatsolittle"berbuilds uponthecoreincoldlegbreaksthatmixingwiththelowerplenum wouldnotbeinhibitedandthereforetheexistingcalculationmixing assumptionismet.(c)BoththeRoverDmethodologyandthefullrisk-informedmethodol-ogyusedintheSTP2013LARrequirethatadequatecorecoolingis providedbytheECCS.Suchconsiderationsincludeboricacidprecip-itation(seeabove)andanyotherdebrismayonfuelcooling otherthan"owblockage.3.PRAlevelofdetail(a)InordertosupportthemanypossibleECCSandContainmentSpraySystem(CSS)con"gurations,thePRAneededtohaveseveraltop eventsadded.Thenecessary"delityandconcomitantmodelsupport detailneededtoaccuratelyrepresentallpossiblecon"gurationsisrel-ativelycomplex.Somereductioncanberealizedbyboundinganal-yses;howevertheprocessusedresultedinmanyRAIs.TheRoverD methodologyavoidsextensiverelianceonthePRAandinfact,uses whatcouldeelybethoughtofasaLOCADebrisinitiating eventfrequencyasaboundingratherthandetailedmodeling inthePRA.Similarly,thePRAmodelofrecordisusedtoevalu-atetheLERFusingtheratioofLERFconditionalonECCSsump screenfailureforLargeBreakLossofCoolantAccident(LLOCA) andCDFconditionalonsumpscreenfailureinLLOCA.Tuesday1 stMarch,2016:19:32,Page19of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Humanreliabilityanalysisisrequiredforthevariousactionsassumedinthedetailedplantmodel(pumpoperation,forexample).Thehu-manreliabilityanalysisincludedinthePRAmodelofrecordalready includeshumanreliabilityanalysisrequiredforinitiatingeventsother thanthedebrisevent(which,whenstrainersuccesscriteriaareex-ceededassumescoredamage).(c)IntheSTP2013LAR,thePRArequiredsomemodi"cationstoaccommodatetheseveralnewECCSstrainerandin-vesselfailure modes.RoverDcreates,inanewinitiatingeventfordebris failureandtheinitiatingeventfrequencyisdirectlyusedasthein-creaseinCDF(theCDF).Inthisway,theSTPPRAdoesnot requiremodi"cationsinceanyinformationneededcanbeobtained directlyfromtheSTPPRA.4.LOCAFrequency(a)Causalmodeling:Themostaccuratemodelingoffailurelikelihood(LossofCoolantAccident(LOCA))atanygivenlocationinthe RCSpressureboundarywouldtakeintoconsiderationfailuremecha-nismsbasedoncausalmodelingoftheunderlyingphenomenathereby producingprobabilitiesforeachlocation.Theoretically,suchvalues couldbeusedinsumstoestimatethe(preferentially)frequency(or likelihood)ofaLOCAofanyparticularsizeinaplant.TheSTP 2013LARusedaweightingschemethatattemptedtopreservethe NUREG1829frequenciesbutadditionallytakingintoaccountin-servicedatawherecrackswereobservedandsomeconsiderationof thetypeofservice.InRoverD,aboundingmethod,calledtop-down, wasadoptedthatavoidstheneedtoaccountforweightingbyrely-ingonthefactthatlocationswheredebrisamountsexceedtested levelshavebeenmitigated.Thatis,theproblematicorriskloca-tionshavebeenmitigatedandonlythenonrisklocationshavenot been.TheRoverDmethodologyignoresthemitigationimprovements andequallyweightstheNUREG1829exceedancefrequenciesforall locationstherebyboundinglocale(b)DEGBversuscontinuummodel:TheSTP2013LARestimatedbreaksofanysizethatcouldbesupportedbyagivenpipediameter.This requiresassumingacontinuumofbreaksizesuptothepipediameter andgivesthemostcompletepictureofpossiblebreaksthatcould beusedinarisk-basedapplication.TheNUREG1829elicitation reportcanbeinterpretedtoindicateonlyDoubleEndedGuillo-tineBreaks(DEGBs)canoccur.Wenoteherethatbothattribu-tionandfrequencymustbeconsideredinanyinterpretation.Inthe RoverDmethodology,thecontinuumbreakmodeliscomparedtothe DEGB-onlymodelofinterpretationanditautomaticallyincludesa (conservative)interpretationofattribution(sphericalZoneOfIn"u-ence(ZOI)foralllocations).(c)Aggregationmodels:NUREG1829includestwoaggregationmethodsforcombiningtheexpertelicitations-arithmeticmeanandgeomet-Tuesday1 stMarch,2016:19:32,Page20of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONricmean.BecausethePRAcommunitymostgenerallyadoptsthegeometricmeanaggregationanditrepresentsamorerealisticesti-mate,theSTP2013LARadoptedthegeometricmeanaggregation.

TheRoverDmethodologyprovidesestimatesofbothaggregations.(d)Sampling:AlltheelicitedexceedancefrequencyquantilesandmeansaggregatedinNUREG1829decreaserapidlywithsizeofbreak.As aconsequence,samplingmustbedoneverycarefullytoensurethe longtailsofthedistributionsarecaptured.ThiswasdoneinCASA GrandeasdescribedintheSTP2013LARusingstrati"edsampling techniquesandensuringthattheDEGBbreaksizewassampledin eachquanti"cation.TheRoverDmethodologyavoidstheneedtoper-formsampling,inthewayrequiredforMonteCarloquanti"cation, byassumingallbreaksizeslargerthanthesmallestbreaksizepro-ducingmoredebristhanwastestedatthelocationareassumedtobe failure.Thisisaconservativeestimatethatalsoavoidsthepossibility ofinadequatesamplingoflongtails.5.FibermassdistributionTheSTP2013LARestimates"bermassdistributionintheRCBpool,thereactorcore,andtheECCSstrainers.ThemethodusedintheSTP 2013LARperformsestimatesforthepumpcon"gurationsassumedand calculatesheadlossbasedoncollectionofparticulates("ber,paint,chem-icalprecipitates).TheRoverDmethodologyperformsasimilarcalculation however,insteadoflookingatallpossiblepumpingcon"gurations,RoverD looksatexpectedandextremecasestoensurethein-vesseleare notlimiting.HeadlosscomputationisnotdoneinRoverD.Instead,re-sultsoftestingonanSTPECCSstrainermoduleareused.Any"ne"ber loadingthatexceedsthetestedamountisassumedtoleadtocoredamage.6.DebrisgenerationandtransportTheSTP2013LARincludedtimingconsiderationsandmanydtbreaksizesandorientations.Forexample,itisreasonabletoconsiderthat paintoutsidetheZOIwouldeithernotfailatallorifitdoesfail,failin relativelylargepiecesoverlongperiodsoftime.RoverDonlyrequiresthat theamountsoffailedcoatingsassumedinthetestareappropriatelycon-servative(acceptedtoexceedamountsexpected)orareotherwisebounded.

Asaconsequence,nomodelingoffailuresizeortimingisrequiredinthe RoverDmethodology.Tuesday1 stMarch,2016:19:32,Page21of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONTable1.1:SummaryofrelevancyofquestionsandresponsesbasedonadoptingtheRoverDmethodology.Therelevancy(RoverDStatus)isindicatedalongwithacross-referencetothequestionQuestion)andtheresponse(Response).Thebasis(Basissum-mary)refersbacktotheimpactsofRoverDtoclassesofcharacteristicssummarized inthedescriptionsinSection1.2thatwouldchangetherelevancyofthequestionand responseStatusQuestionResponseBasissummaryRound1RAIs,APLAB,General,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande-General:Question1aSection1.2,Item1RemovedItem1bAPLAB,CASAGrande-General:Question1bRemovedItem1cAPLAB,CASAGrande-General:Question1cRound1RAIs,APLAB,PlantCon"guration,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande-PlantCon"guration:Question1aSection1.2,Item2aRemovedItem1bAPLAB,CASAGrande-PlantCon"guration:Question1bRemovedItem2aAPLAB,CASAGrande-PlantCon"guration:Question2aSection1.2,Item2aRemovedItem2bAPLAB,CASAGrande-PlantCon"guration:Question2bRemovedItem3aAPLAB,CASAGrande-PlantCon"guration:Question3aSection1.2,Item3aRemovedItem3bAPLAB,CASAGrande-PlantCon"guration:Question3bRemovedItem3cAPLAB,CASAGrande-PlantCon"guration:Question3cRound1RAIs,APLAB,LOCAFrequencies,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande,LOCAFre-quencies:Question1Section1.2,Item4aRemovedItem1bAPLAB,CASAGrande,LOCAFre-quencies:Question1 RequiredItem2APLAB,CASAGrande-LOCAFrequencies:Question2Section1.2,Item4bRemovedItem3APLAB,CASAGrande,LOCAFre-quencies:Question3Section1.2,Item4dRemovedItem4APLAB,CASAGrande,LOCAFre-quencies:Question4Round1RAIs,APLAB,CASAGrandetoPRAInterface,Section1.3.1.1 RequiredItem1aAPLAB,CASAGrande,toPRAIn-terface-General:Question1aSection1.2,Item5 RequiredItem1bAPLAB,CASAGrande,toPRAIn-terface-General:Question1b RequiredItem2aAPLAB,CASAGrandetoPRAInterface-General:Question2aSection1.2,Item4dRemovedItem2bAPLAB,CASAGrandetoPRAInterface-General:Question2bSection1.2,Item6RemovedItem3APLAB,CASAGrande,toPRAIn-terface-General:Question3Section1.2,Item3cRemovedItem4aAPLAB,CASAGrande,toPRAIn-terface-General:Question4aSection1.2,Item3acontinuednextpage...Tuesday1 stMarch,2016:19:32,Page22of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem4bAPLAB,CASAGrande,toPRAIn-terface-General:Question4bRemovedItem4cAPLAB,CASAGrande,toPRAIn-terface-General:Question4cRemovedItem5APLAB,CASAGrande,toPRAIn-terface-General:Question5Section1.2,Item3aRemovedItem6aAPLAB,CASAGrande,toPRAIn-terface-General:Question6aSection1.2,Item4dRemovedItem6bAPLAB,CASAGrande,toPRAIn-terface-General:Question6bRemovedItem6cAPLAB,CASAGrande,toPRAIn-terface-General:Question6cRound1RAIs,APLAB,PRAModel,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-General:Question1Section1.2,Item3 RequiredItem2APLAB,STPPRAModel-Gen-eral:Question2 RequiredItem3APLAB,STPPRAModel-General:Question3Round1RAIs,APLAB,SuccessCriteria,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-SuccessCriteria:Question1Section1.2,Item2bRemovedItem2aAPLAB,STPPRAModel-SuccessCriteria:Question2aSection1.2,Item2cRemovedItem2bAPLAB,STPPRAModel-SuccessCriteria:Question2bSection1.2,Item3a RequiredItem2cAPLAB,STPPRAModel-SuccessCriteria:Question2cSection1.2,Item2aRemovedItem3aAPLAB,STPPRAModel-SuccessCriteria:Question3aSection1.2,Item3aRemovedItem3bAPLAB,STPPRAModel-SuccessCriteria:Question3b RequiredItem3cAPLAB,STPPRAModel-SuccessCriteria:Question3cSection1.2,Item3aRemovedItem3dAPLAB,STPPRAModel-SuccessCriteria:Question3dSection1.2,Item3Round1RAIs,APLAB,HumanReliabilityAnalysis,Section1.3.1.1RemovedItem2APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1Section1.2,Item3cRemovedItem2APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2RemovedItem3aAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3aRemovedItem3bAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3bRemovedItem3cAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3cRemovedItem4aAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question4aRemovedItem4bAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question4bRemovedItem5APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5continuednextpage...Tuesday1 stMarch,2016:19:32,Page23of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem6APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6Round1RAIs,APLAB,PRAScope,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-PRAScope:Question1Section1.2,Item3 RequiredItem2APLAB,STPPRAModel-PRAScope:Question2Round1RAIs,APLAB,ResultsInterpretation,Section1.3.1.1RemovedItem1aAPLAB,ResultsInterpretation-Quanti"cation:Question1aSection1.2,Item3aRemovedItem1bAPLAB,ResultsInterpretation-Quanti"cation:Question1bRemovedItem2APLAB,ResultsInterpretation-Quanti"cation:Question2Round1RAIs,APLAB,UncertaintyAnalysis,Section1.3.1.1 RequiredItem1aAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1aSection1.2,Item6 RequiredItem1bAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1bSection1.2,Item3 RequiredItem1cAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1cSection1.2,Item3a RequiredItem2APLAB,ResultsInterpretation-UncertaintyAnalysis:Question2Section1.2,Item4c RequiredItem3APLAB,ResultsInterpretation-UncertaintyAnalysis:Question

3Section1.2,Item1RemovedItem4aAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4aSection1.2,Item4RemovedItem4bAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4bRemovedItem4cAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question 4cRemovedItem4dAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4dRemovedItem5APLAB,ResultsInterpretation-UncertaintyAnalysis:Question

5RemovedItem6APLAB,ResultsInterpretation-UncertaintyAnalysis:Question 6Round1RAIs,ACRB RequiredItem1ARCB:Question1Doseconsequnces RequiredItem2ARCB:Question2 RequiredItem3ARCB:Question3Round1RAIs,EMCB RequiredItem1ECMB,Question1Strainermechanicalcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page24of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem2EMCB,Question2StrainermechanicalRound1RAIs,EPNBRemovedItem1ENPB,Question1Section1.2,Item4RemovedItem2ENPB,Question2RemovedItem3ENPB,Question3RemovedItem4ENPB,Question4RemovedItem5ENPB,Question5 RequiredItem6aENPB,Question6aLOCAfrequency/ISIprogram RequiredItem6bENPB,Question6bRound1RAIs,ESGB,ChemicalRemovedItem1aESGB,ChemicalQuestion 1aSection1.2,Item5RemovedItem1bESGB,ChemicalQuestion 1bRemovedItem1cESGB,ChemicalQuestion 1cRemovedItem1dESGB,ChemicalQuestion 1dRemovedItem2ESGB,ChemicalQuestion2RemovedItem3ESGB,ChemicalQuestion3RemovedItem4ESGB,ChemicalQuestion4RemovedItem5ESGB,ChemicalQuestion5RemovedItem6ESGB,ChemicalQuestion6RemovedItem7ESGB,ChemicalQuestion7RemovedItem8ESGB,ChemicalQuestion8RemovedItem9ESGB,ChemicalQuestion9RemovedItem10ESGB,ChemicalQuestion 10RemovedItem11aESGB,ChemicalQuestion 11a RequiredItem11bESGB,ChemicalQuestion 11bRemovedItem12ESGB,ChemicalQuestion 12Section1.2,Item1RemovedItem13aESGB,ChemicalQuestion 13aRemovedItem13bESGB,ChemicalQuestion 13bRemovedItem13cESGB,ChemicalQuestion 13c RequiredItem14aESGB,ChemicalQuestion 14aTestisrequiredtobebounding RequiredItem14bESGB,ChemicalQuestion 14b RequiredItem14cESGB,ChemicalQuestion 14cRemovedItem15ESGB,ChemicalQuestion15Section1.2,RoverDimpactsRemovedItem16ESGB,ChemicalQuestion 16RemovedItem17ESGB,ChemicalQuestion 17 RequiredItem18aESGB,ChemicalQuestion 18aUseofAlOOHsurrogatecontinuednextpage...Tuesday1 stMarch,2016:19:32,Page25of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem18bESGB,ChemicalQuestion 18bSection1.2,Item5RemovedItem18cESGB,ChemicalQuestion 18cRemovedItem19ESGB,ChemicalQuestion 19RemovedItem20ESGB,ChemicalQuestion 20 RequiredItem21ESGB,ChemicalQuestion 21Testingresults,SM RequiredItem22aESGB,ChemicalQuestion 22a RequiredItem22bESGB,ChemicalQuestion 22bRound1RAIs,ESGB,CoatingsRemovedItem1ESGB,Coatings:Question1Section1.2,Item6 RequiredItem2ESGB,Coatings:Question2Testingresults,SMRemovedItem3ESGB,Coatings:Question3Section1.2,Item6RemovedItem4ESGB,Coatings:Question4RemovedItem5ESGB,Coatings:Question5 RequiredItem6aESGB,Coatings:Question6a2008TestingassumedIOZZOIRemovedItem6bESGB,Coatings:Question6bSection1.2,Item6RemovedItem6cESGB,Coatings:Question6c RequiredItem7ESGB,Coatings:Question7CoatingsprogramdescriptionRound1RAIs,SCVB RequiredItem1aSCVB,Question:1aUFSARchanges,exemptions RequiredItem1bSCVB,Question:1b RequiredItem2aSCVB,Question:2a RequiredItem2bSCVB,Question:2b RequiredItem3aSCVB,Question:3a RequiredItem3bSCVB,Question:3b RequiredItem3cSCVB,Question:3c RequiredItem4aSCVB,Question:4a RequiredItem4bSCVB,Question:4b RequiredItem4cSCVB,Question:4c RequiredItem5SCVB,Question:5RoverDdoesnotchangethecontainmentanalysis(currentLBcalculationisused).

RequiredItem6SCVB,Question:6 RequiredItem7SCVB,Question:7 RequiredItem8SCVB,Question:8RELAP5screeningcases RequiredItem9aSCVB,Question:9aUFSARchanges,exemptions RequiredItem9bSCVB,Question:9bRound1RAIs,SNPB RequiredItem1aSNPB,Question:1a RequiredItem1bSNPB,Question:1b RequiredItem1cSNPB,Question:1c RequiredItem1dSNPB,Question:1dUsedbyNRCfortheirthermal-hydraulicreview RequiredItem1eSNPB,Question:1e RequiredItem1fSNPB,Question:1f RequiredItem1gSNPB,Question:1g RequiredItem1hSNPB,Question:1h RequiredItem1iSNPB,Question:1i RequiredItem1jSNPB,Question:1j RequiredItem1kSNPB,Question:1k RequiredItem1lSNPB,Question:1lcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page26of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem1mSNPB,Question:1m RequiredItem2aSNPB,Question:2a RequiredItem2bSNPB,Question:2b RequiredItem2cSNPB,Question:2c RequiredItem2dSNPB,Question:2d RequiredItem3SNPB,Question:3 RequiredItem4SNPB,Question4STPBAPLBcalculation RequiredItem5SNPB,Question:5Round1RAIs,SRXB RequiredItem1dSRXB,Question1NRCreviewofRELAP5documentation RequiredItem2eSRXB,Question2 RequiredItem3SRXB,Question3 RequiredItem4SRXB,Question4RemovedItem5aSRXB,Question5aLimitingvaluesused RequiredItem5bSRXB,Question5bSection1.2,Item6RemovedItem5cSRXB,Question5cTablenotusedRemovedItem6SRXB,Question6LBContainmentanalysis RequiredItem7aSRXB,Question7aSTPBAPLBcalculation RequiredItem7bSRXB,Question7b RequiredItem8SRXB,Question8Coreblockageislimitcase RequiredItem9SRXB,Question9StrainerpenetrationRound1RAIs,SSIB,DebrisCharacteristics RequiredItem1SSIB,ZOI:Question1 RequiredItem2SSIB,DebrisCharacteristics:Ques-tion2RemovedItem3SSIB,DebrisCharacteristics:Ques-tion3Round1RAIs,SSIB,Transport RequiredItem4SSIB,Transport:Question4DebristransportinCASAstillrequired RequiredItem5SSIB,Transport:Question5 RequiredItem6aSSIB,Transport:Question6a RequiredItem6bSSIB,Transport:Question6b RequiredItem6cSSIB,Transport:Question6c RequiredItem6dSSIB,Transport:Question6d RequiredItem6eSSIB,Transport:Question6e RequiredItem7aSSIB,Transport:Question7a RequiredItem7bSSIB,Transport:Question7b RequiredItem7cSSIB,Transport:Question7c RequiredItem7dSSIB,Transport:Question7d RequiredItem7eSSIB,Transport:Question7e RequiredItem7fSSIB,Transport:Question7f RequiredItem8aSSIB,Transport:Question8a RequiredItem8bSSIB,Transport:Question8bRemovedItem8cSSIB,Transport:Question8cCorrelationsarenotusedinRoverDRemovedItem8dSSIB,Transport:Question8d RequiredItem8eSSIB,Transport:Question8e RequiredItem9SSIB,Transport:Question9DebristransportcalculationsinCASAarestillrequired RequiredItem10SSIB,Transport:Question10RemovedItem11aSSIB,Transport:Question11aCorrelationsarenotusedinRoverDRemovedItem11bSSIB,Transport:Question11bRemovedItem11cSSIB,Transport:Question11cRemovedItem11dSSIB,Transport:Question11dRemovedItem11eSSIB,Transport:Question11eRemovedItem12SSIB,Transport:Question12continuednextpage...Tuesday1 stMarch,2016:19:32,Page27of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem13SSIB,Transport:Question13Round1RAIs,SSIB,HeadLossandChemicalBumpUpRemovedItem14SSIB,HeadLossandChemicalEf-fectsBumpUp:Question14RemovedItem15aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15aHeadlosscorrelationsarenotusedinRoverDRemovedItem15bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15bRemovedItem15cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15cRemovedItem15dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15dRemovedItem16aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16aRemovedItem16bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16bRemovedItem16cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16cRemovedItem16dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16dRemovedItem17aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17aRemovedItem17bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17bRemovedItem17cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17cRemovedItem17dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17dRemovedItem17eSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17eRemovedItem17fSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17fRemovedItem18aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18aRemovedItem18bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18bRemovedItem18cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18cRemovedItem18dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18dRemovedItem18eSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18eRemovedItem19SSIB,HeadLossandChemicalEf-fectsBumpUp:Question19RemovedItem20SSIB,HeadLossandChemicalEf-fectsBumpUp:Question20RemovedItem21aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21aRemovedItem21bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21bRemovedItem21cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21cRemovedItem21dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21dcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page28of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem22SSIB,HeadLossandChemicalEf-fectsBumpUp:Question22RemovedItem23SSIB,HeadLossandChemicalEf-fectsBumpUp:Question23RemovedItem24SSIB,HeadLossandChemicalEf-fectsBumpUp:Question24RemovedItem25aSSIB,HeadLossandChemicalEf-fectsBump-up:Question25aRemovedItem25bSSIB,HeadLossandChemicalEf-fectsBump-up:Question25bRemovedItem26aSSIB,HeadLossandChemicalEf-fectsBump-up:Question26aRemovedItem26bSSIB,HeadLossandChemicalEf-fectsBump-up:Question26b RequiredItem26cSSIB,HeadLossandChemicalEf-fectsBump-up:Question26cStrainerloadingrelatedtoactualperformancecomparedtotestRemovedItem26dSSIB,HeadLossandChemicalEf-fectsBump-up:Question26dHeadlosscorrelationsarenotusedinRoverDRemovedItem26eSSIB,HeadLossandChemicalEf-fectsBump-up:Question26eRemovedItem26fSSIB,HeadLossandChemicalEf-fectsBump-up:Question26f RequiredItem27SSIB,HeadLossandChemicalEf-fectsBumpUp:Question27StrainerLBNPSHRemovedItem28SSIB,HeadLossandChemicalEf-fectsBumpUp:Question28HeadlosscorrelationsarenotusedinRoverDRound1RAIs,SSIB,NPSHandDegasi"cation RequiredItem29SSIB,NPSHandDegasi"cation:Question29StrainerLBNPSH RequiredItem30SSIB,NPSHandDegasi"cation:Question30 RequiredItem31SSIB,NPSHandDegasi"cation:Question31 RequiredItem32SSIB,NPSHandDegasi"cation:Question32 RequiredItem33SSIB,NPSHandDegasi"cation:Question33 RequiredItem34SSIB,NPSHandDegasi"cation:Question34Strainerpenetrationdependson"owrateRemovedItem35SSIB,NPSHandDegasi"cation:Question35RoverDusesthepipeinsidediame-terforDEGBfrequencyevaluation RequiredItem36SSIB,NPSHandDegasi"cation:Question36StrainerLBNPSHRound1RAIs,SSIB,In-VesselandBoricAcidPrecipitation RequiredItem37SSIB,In-VesselandBoricAcidPre-cipitation:Question37StrainerLBBAPcalculationRound1RAIs,SSIB,DebrisBypass RequiredItem38SSIB,NPSHandDegasi"cation:Question38 RequiredItem39(a)iiiSSIB,DebrisBypass:Question39aDebrisbypassisrequiredfordownstreamanalysisinRoverD.

RequiredItem39bSSIB,DebrisBypass:Question39b RequiredItem39cSSIB,DebrisBypass:Question39c RequiredItem39dSSIB,DebrisBypass:Question39d RequiredItem39eSSIB,DebrisBypass:Question39econtinuednextpage...Tuesday1 stMarch,2016:19:32,Page29of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem39fSSIB,DebrisBypass:Question39fRound1RAIs,SSIB,DefenseInDepthandMitigativeMeasures RequiredItem40SSIB,DefenseInDepthandMitiga-tiveMeasures:Question40DIDandSMrequiredbyRG1.174 RequiredItem41aSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41a RequiredItem41bSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41b RequiredItem41cSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41c RequiredItem41dSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41d RequiredItem42SSIB,DefenseInDepthandMitiga-tiveMeasures:Question42Round1RAIs,STSB RequiredItem1STSB:Question1TSsubmittedaspartofLAR RequiredItem2STSB:Question2 RequiredItem3STSB:Question3Round2RAIs,APLAB,ProjectQualityAssurance RequiredItem1Question1:ProjectQualityAssur-anceAppropriatequalitycontrolsrequiredforlicenseactivities RequiredItem2Question2:ProjectQualityAssur-ance RequiredItem3Question3:ProjectQualityAssur-ance RequiredItem4Question4:ProjectQualityAssur-anceRound2RAIs,APLAB,TreatmentofUnanalyzedPlantConditionsRemovedItem1cQuestion1:TreatmentofUnana-lyzedPlantConditionsSection1.2,Item3Round2RAIs,APLAB,HumanReliabilityAnalysisRemovedItem7Question7:HumanReliability AnalysisBoundinganalysisforoperatorre-sponse(allriskcategoriesassume coredamage)Section1.2,Item3.Round2RAIs,APLAB,KeyAssumptions/KeySourcesofUncertaintyRemovedItem1gQuestion1:KeyAssumptions/KeySourcesofUncertaintySection1.2,Item1.Round2RAIs,APLAB,ValidityofAssumptiononPumpCon"gurationsRemovedItem1Question1:ValidityofAssumptiononPumpCon"gurationsSection1.2,Item2.Round2RAIs,Round2RAIs,APLAB,CASAGrandetoPRAInterfaceRemovedItem7Question7:CASAGrandetoPRAInterfaceThemethodologynowstrictlylooksforsmallestbreaksizebelowwhichtested"nesamountsarenotex-

ceeded.Round2RAIs,APLAB,FidelitybetweenRELAPSimulationsandCASAGrande RequiredItem1Question1:FidelitybetweenRELAPSimulationsandCASA

Grande(Partiallyrequired)Section1.2,Item4d.Round2RAIs,APLAB,State-of-KnowledgeCorrelationcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page30of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem1Question1:State-of-Knowledge CorrelationRoverDdoesnotcalculatefail-ureprobabilities.Instead,RoverD calculatescoredamagefrequenciescomefromdirectevaluationoftheNUREG1829quantilesandmeans.Round2RAIs,Round2RAIs,APLAB,SelectionofJohnsonParametersRemovedItem1Question1:SelectionofJohnsonPa-rametersRoverDevaluatescalculatescoredamagefrequenciesfromdirecteval-uationoftheNUREG1829quan-tilesandmeans.Round2RAIs,EMCB RequiredItem2Question2StrainermechanicalmustbemetforRoverD.Round2RAIs,ESGB,ChemicalRemovedItem23Question23:ChemicalRoverDdoesnotusecorrelationstoevaluatestrainerheadloss.RemovedItem24dQuestion24:ChemicalRemovedItem25dQuestion25:ChemicalRemovedItem26cQuestion26:ChemicalRemovedItem27Question27:ChemicalRemovedItem28[ML15091A440]Question28:Chem-icalRemovedItem29Question29:ChemicalRemovedItem30Question30:ChemicalRemovedItem31Question31:ChemicalRemovedItem32Question32:Chemical RequiredItem33Question33:ChemicalCouldhaveimpactontestedamountofparticulateandCRUDctson headloss(astested.)RemovedItem34Question34:ChemicalRoverDdoesnotusecorrelationstoevaluatestrainerheadloss.Round2RAIs,ESGB,CoatingsRemovedItem8Question8:CoatingsAllunquali"edcoatingswerein-cludedintheSTP2008strainertestusedbyRoverD.

RequiredItem9Question9:CoatingsTheSTP2008strainertestbasisneedstobeshownconsistentwithNRC-required

assumptions.

RequiredItem10Question10:CoatingsRound2RAIs,SCVB RequiredItem10cQuestion10UFSARchangesandexemptionrequestsarerequiredforRoverD.

RequiredItem11ML15246A128,Question11 RequiredItem(1)ML15246A128,Question12(1)

RequiredItem(2)ML15246A128,Question12(2)

RequiredItem(3)ML15246A128,Question12(3)

RequiredItem(4)ML15246A128,Question12(4)

RequiredItem12aML15246A128,Question12(4)a RequiredItem12bML15246A128,Question12(4)b RequiredItem13ML15246A128,Question13 RequiredItem(1)ML15246A128,Question14(1)

RequiredItem(2)ML15246A128,Question14(2)

RequiredItem(3)ML15246A128,Question14(3)

RequiredItem(4)ML15246A128,Question14(4)

RequiredItem(5)ML15246A128,Question14(5)

RequiredItem(a)ML15246A128,Question14(5)(a)continuednextpage...Tuesday1 stMarch,2016:19:32,Page31of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem(b)ML15246A128,Question14(5)(b)

RequiredItem15ML15246A128,Question15 RequiredItem(1)ML15246A128,Question16(1)

RequiredItem(2)ML15246A128,Question16(2)

RequiredItem(3)ML15246A128,Question16(3)

RequiredItem(4)ML15246A128,Question16(4)

RequiredItem(5)ML15246A128,Question16(5)

RequiredItem(a)ML15246A128,Question16(5)(a)

RequiredItem(b)ML15246A128,Question16(5)(b)

RequiredItem17ML15246A128,Question17 RequiredItem(d)ML15246A128,Question18(a)(b)(c)(d)Round2RAIs,SNPB RequiredItem1Question6BAPmustbemetinRoverD RequiredItem2Question7 RequiredItem3Question8 RequiredItem4Question9RemovedItem5Question10RoverDdoesnotrelyonHLSOtim-ingRound2RAIs,SSIB RequiredItem43Question43RoverDusesdebrisgenerationandtransport to"ndcritical/non-criticalweldlocations RequiredItem44Question44 RequiredItem45Question45 RequiredItem46Question46RemovedItem47Question47HeadlosscorrelationsarenotusedinRoverD.ChemicalarefromtestingRemovedItem48Question48 RequiredItem49Question49RoverDrequiresstrainerperfor-mancecalculationRemovedItem50Question50RoverDdoesnotusecorrelationsforheadloss RequiredItem51Question51RoverDrequiresstrainerperformancecalculation RequiredItem52Question52RemovedItem53Question53RoverDdoesnotusedistributionsforperformancemodeling RequiredItem54Question54RoverDrequiresstrainerperfor-mancecalculation RequiredItem55Question55RoverDrequiresDIDdescription RequiredItem55aQuestion55aRoverDdoesnotusecorrelationsforheadloss RequiredItem56Question56RoverDrequiresstrainerpenetrationcalculation RequiredItem57aQuestion57(a)

RequiredItem57bQuestion57(b)

RequiredItem57cQuestion57(c)

RequiredItem57dQuestion57(d)

RequiredItem57eQuestion57(e)

RequiredItem57fQuestion57(f)RemovedItem58Question58RoverD"berloadingonlyforbreaksizedetermination RequiredItem59Question59RoverDrequirestheCADmodelandCASAGrandefordebrisgenerationandtransport RequiredItem60Question60Latent"beranderoded"berarere-quiredforRoverDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page32of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem61Question61RoverDrequirestheCADmodelandCASAGrandefordebrisgeneration andtransportRemovedItem62Question62RoverDdoesnotusecorrelationsforheadloss RequiredItem63Question63RoverDrequirestheCADmodelandCASAGrandefordebrisgeneration andtransportRemovedItem64Question64RoverDdoesnotusecorrelationsforheadlossRemovedItem65Question65 RequiredItem66Question66RoverDrequiresBAPcalculationRound2RAIs,STSB RequiredItem4Question4Applicationtoclarifyuseofriskin-formationTuesday1 stMarch,2016:19:32,Page33of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.3Round1RAIs1.3.1APLAProbabilisticRiskAssessmentLicensingBranch1.3.1.1CASAGRANDE

• General1.RegulatoryGuide(RG)1.174,Revision2,AnApproachforUsingProbabilisticRiskAssessmentinRisk-InformedDecisionsonPlant Speci"cChangestotheLicensingBasis,May2011(ADAMSAcces-sionNo.ML100910006),Section2.3.3,ProbabilisticRiskAssess-mentTechnicalAdequacy,statesthatthePRAmodelshouldbe technicallyadequatefortheapplication.Volume6.2containsalist ofinputvariablesanddescribeswhethereachvariablewasmodeled asapointestimateoradistributioninCASAGrande.Accordingto item5.d(page158of179),thedecisionastowhethertouseapoint estimateoradistributionwasbasedontheavailabilityofdataforun-certaintyanalysisandtheavailableconsensusonthevaluesassigned tospeci"cfactors(e.g.,forsomevalues,thereisahighlevelofcon-

"dencebyindustryandNRC).Pleasedescribetheprocessusedto assignpointestimatesordistributionsinmoredetail.Foreachinput parameter,pleaseprovide:(a)Thebasisforusingapointestimateoradistribution.RemovedResponse,Pg.224(b)Thesourceoftheparametervalue(e.g.,licensingbasiscalcula-tion).RemovedResponse,Pg.235(c)WhethertheparameterisbasedonanNRC-acceptedvalue(e.g.,asdocumentedinthesafetyevaluation(SE)forNEI-04-07,Pres-surizedWaterReactorSumpPerformanceEvaluationMethodol-ogy(PackageADAMSAccessionNo.ML043280641).RemovedResponse,Pg.235

• CASAGrande,PlantCon"guration1.RG1.200,Revision2,AnApproachforDeterminingtheTechnicalAdequacyofProbabilisticRiskAssessmentResultsforRisk-Informed Activities,Revision2(ADAMSAccessionNo.ML090410014),Sec-tion1.4,PRADevelopment,Maintenance,andUpgrade,statesthat plantinformationusedinthePRA(e.g.,expectedthermal-hydraulic plantresponsetodtstatesofequipment)shouldbeasrealis-ticaspossible.Thermal-hydraulicsimulationsdescribedinVolume 6.2showthatpooltemperatureisbyparameterssuchas loss-of-coolantaccident(LOCA)breaksize,componentcoolingwa-ter(CCW)temperature,andthestatusofcontainmentspray,resid-ualheatremoval(RHR),andcontainmentfancoolers.Thesimpli-

"edcurvesusedbyCASAGrande(Volume3,Figure2.2.13)assume nominalvaluesfortheseparametersandanintactcontainment (Volume6.2,page6)yetareassumedtobeboundingbasedonqual-itativeargumentsstatedbyVolume3,Assumption1k,page72.(a)Pleasestateifvaryingtheaforementioned(orother)parame-tersfromtheirnominalvaluesproducetime-temperaturecurvesTuesday1 stMarch,2016:19:32,Page34of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthatwouldyieldhigherconditionalprobabilitiesofsumporcoreblockageforanydurationoftimeduringtheevent.Pleaseinclude considerationofall15pumpstate-LOCAsizecombinations(i.e.,

"vepumpcases1,9,22,26,and43,andthreeLOCAcategories (S/M/L[small/medium/large])forbothscenarioswherecontain-mentisintactandnotintact.RemovedResponse,Pg.235(b)Pleaseprovideatechnicaljusti"cationforusingonlynominalvaluesorcalculatecoredamagefrequency(CDF),largeearly releasefrequency(LERF),delta-CDFanddelta-LERF usingtime-temperaturecurvesthatmaximizetheprob-abilityofsumpandcoreblockagefortheentireassumedduration oftheevent.RemovedResponse,Pg.2352.RG1.174,Section2.3.2,LevelofDetailRequiredtoSupportanApplication,statesthatthelevelofdetailofthePRAmodelmust bettomodeltheimpactoftheproposedchange.Section2.2.8 ofVolume3statesthatTable2.2.14safetyinjection(SI)"owrates arebasedonsimulationsusingnominaloperatingconditions(i.e.,

allemergencycorecoolingsystem(ECCS)trainsoperating,allfan coolersoperating,andnominalCCWheatexchangertemperatures).

Furthermore,Volume2,page38statesthattoevaluatethepotential forgenericsafetyissue(GSI)-191phenomena,thetotalpump"ow fromthesumpisthemostimportantconsideration.(a)Pleasestatewhethervaryingtheaforementioned(orother)op-eratingconditionsfromtheirnominalvaluescouldproduce"ow ratesorotherthermal-hydraulicconditionsthatwouldyieldhigher conditionalprobabilitiesofsumporcoreblockageforanydura-tionoftimeduringtheevent.Pleaseincludeconsiderationofall 15pumpstate-LOCAsizecombinations(i.e.,"vepumpcases1, 9,22,26,and43,andthreeLOCAcategories(S/M/L)forboth scenarioswherecontainmentisintactandnotintact.RemovedResponse,Pg.236(b)Pleaseprovideatechnicaljusti"cationforassumingonlynomi-naloperatingconditionsorcalculateCDF,LERF,and using"owratesorotherthermal-hydraulicconditions thatmaximizetheprobabilityofsumpandcoreblockageforthe entireassumeddurationoftheevent.RemovedResponse,Pg.2363.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume3(page71of248),Assumption2bprovidesaqualitative argumentforwhyacombinationofpumpsfailinginthesametrain isworsethanthesamesetofpumpsfailingindttrains.This qualitativeargumentincludesasetofexamplescapturedinVolume 3,Tables3.1,3.2,and3.3.(a)Pleasejustifythisassumptionandclarifyifanengineeringanal-ysiswasperformedinsupportofthisassumption.RemovedResponse,Pg.237(b)Pleasestateifthisassumptionalwaysincreasestheconditionalprobabilityofstrainerfailure(i.e.,isthisaconservativeassump-Tuesday1 stMarch,2016:19:32,Page35of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtion?).Inotherwords,pleaseexplainifthereareanycombina-tionsofpumpsfailinginseparatetrainsthatwouldproducean equalorhigherapproachvelocityandanequalorhigherdebris accumulationonanyonestrainerthanthesamecombinationof pumpsfailinginasingletrain.Ifso,pleasejustifyexcludingthem fromtheanalysis.RemovedResponse,Pg.238(c)Pleasestateifthisassumptionalwaysincreasestheconditionalprobabilityofin-vesseleAssumption2backnowledgesthat somecombinationsofpumpsfailinginseparatetrainsmaypro-duceanequalorhigheramountofdebrisaccumulationinthe corewhencomparedtothesamecombinationofpumpsfailing inasingletrain.Pleaseprovidealistofthesecombinationsand justifyexcludingthemfromtheanalysis.RemovedResponse,Pg.238

• CASAGrande,LOCAFrequencies1.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume3,Section5.3.1(page124 of248)states,inpart,that...therelativeweight[s]ofbreaksinvariousweldlocationsarebasedonspeci"cdegradationmechanismsforcategories ofwelds.Thesefrequenciesweredeterminedfromananal-ysisofOM[degradationmechanism]-dependentweldfailure ratesbasedonservicedata,aBayesmethodforuncertainty treatmentdevelopedinthe[ElectricPowerResearchInstitute (EPRI)]risk-informedin-serviceinspection(RI-ISI)program, andestimatesofconditionalprobabilityversusbreaksizeus-inginformationdevelopedinNUREG-1829[EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElic-itationProcess,April2008(Volumes1and2:ADAMSAc-cessionNos.ML082250436andML081060300)].(a)Althoughnotexplicitlyquanti"ed,factorsotherthanbreaksizewereconsideredbytheNUREG-1829panelistswhendevelop-ingLOCAfrequencies.Forexample,NUREG-1829,Section6.3.2, ImportantAgingMechanisms,describesthepanelistsconsid-erationoffactorssuchasthermalfatigue,"ow-acceleratedcorro-sion,inter-granularstresscorrosioncracking,andmechanicalfa-tigue.Pleasedescribehowthesefactorswereusedtoquantifythe breakfrequencyforvariouspipesizes.Foranyfactorsusedinthe STPpilotanalysisthatwerealreadyconsideredbytheNUREG-1829panelists,pleaseexplainwhytheproposedapproachdoes notamounttodoublecounting.RemovedResponse,Pg.114(b)TheNUREG-1829totalLOCAfrequenciesreferencedbytheSTPpilotapplicationincludecontributionsfrombothpipingand non-piping(e.g.,nozzles,componentbodies,pressurizerheatersleeves,manways,andcontrolroddrivemechanismpenetra-tions)weldfailures.AsshowninNUREG-1829,Figure7.7,theTuesday1 stMarch,2016:19:32,Page36of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcontributionfromnon-pipingLOCAscanbesigni"cantandex-ceedsthecontributionfrompipingLOCAsforseveralcategories.

TheapproachdescribedinVolume3,Section5.3,LOCAFre-quency,oftheSTPNOCsubmittaldistributesthetotalLOCA frequenciesontopipeweldsonly.Whilethispreservestheover-allinitiatingeventfrequency,itdoesnotexplicitlyconsiderthe debrisgeneration,transport,etc.ofLOCAscausedbythesecon-tributors.Pleaseexplainhowthedebris-relatedriskfromnon-pipingcontributorswasestimatedinthisstudy.Pleaseprovidea justi"cationforanynon-pipingcontributorsthatwereexcluded fromtheanalysis.Removed,clari"-cationrequestedResponse,Pg.1142.RG1.174,Section2.3.4,PlantRepresentation,statesthatPRAre-sultsshouldbederivedfromamodelthatrealisticallyrepresentstheriskassociatedwiththeplant.NUREG-1829statesthat,ingeneral, acompleteruptureofapipeismorelikelythanapartialrupture.

Itappears,however,thatSTPsmethodologyleadstotheopposite result(i.e.,aruptureofagivensizeismorelikelytobecausedbya partialruptureofalargepipethanacompleteruptureofasmaller pipe).Pleaseillustratetheresultsofyourmethodbycomparingthe frequencyofpartialversuscompletebreaksforasetofrepresenta-tivepipesizes.Pleasedescribewhetherthemethodologydescribedin theSTPpilotisconsistentwiththeassumptionofNUREG-1829or providejusti"cationforanalternateapproach.

RequiredResponse,Pg.1803.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume3,Section5.3describestheprocessusedtode"nenon-uniform samplebinsforeachweldcase.Althoughthissectiondescribesthe processusedtodeterminethenumberofbinsforagivenweld,the processusedtode"nethebinsizesisnotdiscussed.Pleaseprovidea descriptionofthisprocess.RemovedResponse,Pg.1154.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.Volume3describestheprocess usedtoassignbreakfrequenciestoweldsincontainmentandcites thefollowingtwodocumentslistedasReferences7and8:

-Reference7:KNFConsultingServicesLLCandScandpowerRiskManagementInc.DevelopmentofLOCAInitiatingEventFre-quenciesforSouthTexasProjectGSI-191FinalReportfor2011 WorkScope.September2011.

-Reference8:UniversityofTexasatAustin.ModelingandSam-plingLOCAFrequencyandBreakSizeforSTPGSI-191Resolu-tion.September2012.PleaseprovideReference7onthedocketandclarifyexactlywhichaspectsoftheaforementionedreferences(e.g.,byprovidingspeci"c sectionorequationnumbers)areusedintheSTPpilot.RemovedResponse,Pg.116

• CASAGrandetoPRAInterfaceTuesday1 stMarch,2016:19:32,Page37of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.Page3ofEnclosure1ofletterdatedNovember13,2013,states:Fail-uremodesleadingtocoredamageareexplicitlymodeled,excluding thosethatwerepreviouslyaddressedfortheplantusingdetermin-isticevaluations.Also,basedoninformationonpage20ofVolume 3CASAGrandedoesnotanalyzefailuremechanisms4and6(ex-vesseleandcrudonclad,respectively)becausetheyhaveal-readybeenaddresseddeterministically.Thisisinconsistentwiththe risk-informedapproachassetforthinRG1.174,Section1,Element 1:De"netheProposedChange,inthatthelicenseeshouldidentify thoseaspectsoftheplantslicensingbasis(LB)thatmaybe bytheproposedchange.(a)Pleaseprovideabasisforexcludingthetwofailuremechanisms(4and6)fromtheriskassessment.

RequiredResponse,Pg.116(b)PleaseidentifyotherfailuremechanismsorassumptionsrelatedtoGSI-191phenomenathatrelyondeterministicacceptancecri-teria(includingdeterministiccriteriaacceptabletotheNRC) thatwerenotincludedintheriskassessment.

RequiredResponse,Pg.1162.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

PRAmodelstypicallyclassifyLOCAbreaksizesaccordingtoscenario andcorrespondinginstructures,systems,and components(SSCs)availabletomitigatetheeventandcorrespond-ingsuccesscriteria.Fordeterminingtheofdebrisontheseven failuremechanismsde"nedinthesubmittal,adtsetofbreak sizesmightbemoreappropriate.Forexample,ifthereisaminimum sizeLOCAnecessarytoresultinfailureofrecirculationduetodebris, thenincludingLOCAsbelowthatsizewhendeterminingfailureprob-abilitiesmaymaskthetrueriskimpact.Pleaseprovidethefollowing

information:(a)Thelargestbreaksizebelowwhichnofailureswererecordeddur-ingtheCASAruns.Required(Dsmall i)Response,Pg.238(b)Inaddition,forthechosenLOCAsizes,pleasedescribescenariotimingdforthedebrismodelcomparedtothebase PRA,changesinsuccesscriteriaasaresultofdebris,andchanges inoperatorresponse.RemovedResponse,Pg.2383.RG1.174Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbettomodeltheimpactoftheproposedchange.Table 2.2.11(Volume3,page43of248)providesthefrequencyofsuccess pumpcombinationstates.Pleaseexplainwhatthistermmeans,how thefrequenciesinthecolumntitled,PumpStateFrequencywere derived,andhowtheywereusedintheanalysis(bothCASAGrande andthePRAmodels).RemovedResponse,Pg.1174.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Assumption4onpage6ofVolume 2states,inpart,thatTheCASAGrandemodelsassumecontainmentsystemsareTuesday1 stMarch,2016:19:32,Page38of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsuccessful(containmentpurgeisolation,isolationofsmallcontainmentpenetrations,thatatleasttwoofsixfancoolers operate,andthatCCWisavailabletotheRHRheatexchang-ers)forpurposesofevaluatingsumpfailureprobabilities.HighlevelrequirementLE-EofAmericanSocietyofMechanicalEn-gineers/AmericanNuclearSociety(ASME/ANS)RA-Sa2009(The ASMEPRAStandard)states:Thefrequencyoftcontain-mentfailuremodesleadingtoalargeearlyreleaseshallbequanti"ed andaggregated.Pleaseprovidethefollowinginformationforacci-dentscenarioswherethecontainmentisnotsuccessfullyisolatedor wheresomecontainmentsystemsdonotoperateasassumed:(a)Pleaseexplainwhethertheprobabilitiesofthevariousdebris-relatedfailuremechanismsaretforsuchscenarios.RemovedResponse,Pg.117(b)Pleaseexplainhowanyinthoseprobabilitiesareac-countedforinthePRAmodel.RemovedResponse,Pg.118(c)PleaseexplainhowtheaboveassumptionforCASAGrandemeetshighlevelrequirementLE-EofthePRAStandard.RemovedResponse,Pg.1185.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume2,page25states,inpart,thatEarlyonintheassessmentofGSI-191phenomenaitwasdeterminedthattheonlysequenceclassesrequiringsumpre-circulationthatwouldbectedaremediumLOCAs(2-6diameterbreaks)andlargeLOCAs(6diameterbreaks).Also,Volume1,page24states,inpart,thatNofailureswererecordedforsmall-ormedium-breakevents,andittranspiredthatonlythehigherrangeoflarge-break eventscontributedtofailure.Inadditiontothecomposite PRAfailuremodes,totalfailureprobabilityconditionedon theLOCAcategoryisprovided.PRAmodelsoftenincludehighandlowpressurerecirculationineventtreesforsmallLOCAs.Pleaseexplainhowitwasdeterminedthat onlymediumandlargeLOCAswouldrequiresumprecirculation.

Also,pleaseexplainwhytherewerenofailuresforsmallormedium LOCAs,includinganexplanationofthephysicalphenomenathat ledtothisresult.Pleaseincludeinthisexplanationastatementas towhetherthisresultwasduetotdebrisgenerationor Volume3,page81,Assumption11.RemovedResponse,Pg.1196.RG1.174Section2.2statesthatitisessentialtheuncertaintiesberecognizedwhenassessingwhethertheprinciplesofrisk-informed decision-makingaremet.Page84,Volume2states,inpart,thatThefailureprobabilitiesfor[TopEventSUMP]areprovideddirectlyfromCASAGRANDEoutputinVolume3.Theun-certaintyinthesefailureprobabilities[is]reportedasdiscrete probabilitydistributionswith5pointseach.Tuesday1 stMarch,2016:19:32,Page39of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONThisappearstocon"ictwithVolume3,Section6(page233),whichstatesthat15pointestimatesofconditionalfailureprobabilityare averagedforusebythePRA.(a)Pleaseexplainhowmanypointestimates(i.e.,distinctcondi-tionalfailureprobabilities)associatedwithasinglefrequencyvs.

breaksizecurve(e.g.,onecurvefrom"gure6.1inVolume3)were computedbyCASAGrande?RemovedResponse,Pg.119(b)WeretheseparameterspassedtothePRAasaprobabilitymassfunction,probabilitydensityfunction,orasasinglemeanvalue?RemovedResponse,Pg.119(c)PleaseexplainhowwerethesepointestimatesusedinthePRAparameteruncertaintyevaluation?RemovedResponse,Pg.120

• STPPRAMODEL1.RG1.200,Section2.2,IndustryPeerReviewProgram,statesthatwhentheNRCsregulatorypositionscontainedinitsappen-dicesaretakenintoaccount,useofapeerreviewcanbeusedto demonstratethatthePRAisadequatetosupportarisk-informed application.ItappearsthatthelatestpeerreviewoftheSTPPRA modelwasperformedtosupportSTPsapplicationforrisk-managed technicalspeci"cationsandtheresultsofthispeerreviewwerecap-turedbySTPinitsletterdatedFebruary28,2007(ADAMSAcces-sionNo.ML070670369).Pleasedescribeanysigni"cantchangesto theplantorPRAmodelthathavebeenmadesincethattime.Please stateifanyofthesechangesrepresentmodelupgradesasdiscussed intheASME/ANSPRAStandard.Pleaseprovidetheresultsofany focused-scopeorfullpeerreviewsconductedsinceletterdatedFebru-ary28,2007.Required(generalPRAquestion)Response,Pg.2402.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.Pleaseexplainthebasisofthe statementonpage11ofLAREnclosure3sincetheSTPNOCsPRA iscompliantwithRG1.200,Revision1forinternalevents,itiscom-pliantwithRG1.200,Revision2forassessingtheriskassociatedwith GSI-191.Pleaseexplainhowthisconclusionisreached.Required(generalPRAquestion)Response,Pg.1803.RG1.200,Section2.1,ConsensusPRAStandards,statesthatthecapabilitycategory(CC)neededforeachtechnicalrequirementis dependentonthespeci"capplication,althoughCC-IIisgenerally acceptable.Pleaseprovidealistofthesupportingrequirementsand correspondingCCsthatweredeterminedtobeapplicabletotherisk-informedresolutionofGSI-191.ForanycaseswherethenecessaryCC wasnotfoundtohavebeenmetbythepeerreviewprocess,please provideatechnicaljusti"cation.Required(generalPRAquestion)Response,Pg.240

• SuccessCriteria1.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume2,page7,item14,states:Tuesday1 stMarch,2016:19:32,Page40of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONOneoutofthreeeachfromHHSI[highheadsafetyinjec-tion]andLHSI[lowheadsafetyinjection]pumpsisassumed requiredformitigationofmediumLOCAs.Pleaseprovidethebasisforthisassumptionincludinghowdebrisonsuccesscriteriawereconsidered.

RequiredResponse,Pg.2412.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.ASME/ANSRa-Sa-2009SC-83

states:Whende"ningsuccesscriteria,USEthermal/hydraulic,struc-tural,orotheranalyses/evaluationsappropriatetotheevent beinganalyzed,andaccountingforalevelofdetailconsistent withtheinitiatingeventgrouping(HLR-IE-8)andaccident sequencemodeling(HLR-AS-AandHLR-AS-8).Volume3,Section5.10,In-VesselDownstream(page222),andVolume6.2,Item5.a.14describeaseriesofRELAP5simulations usedtoassesssmall,medium,andlargeLOCAsonboththehot-andcold-legsideofthereactorcoolantsystem(RCS)underfullcore blockageconditions.Accordingtothesesections,onlythemedium andlargecoldlegbreaksproceededtocoredamage...(a)Pleasediscusshowthesethermal-hydraulicanalysescontainedalevelofdetailconsistentwiththeinitiatingeventgroupingand accidentsequencemodeling.Inotherwords,explainwhetherthe breaksizesandlocationsassumedintheRELAP5simulations wereconsistentwiththoseusedinthePRAandelsewherein CASAGrande.RemovedResponse,Pg.242(b)PleaseexplainwhethertheplantconditionsassumedintheRE-LAP5simulations(e.g.,numberofavailableECCStrains)were consistentwitheachaccidentsequenceinwhichtheresultsfrom theRELAP5simulationswereused.Forexample,asequencein-volvingplantstate43(singleECCStrain)andamedium-break LOCAonthehot-legsidewouldappeartohaveassumedcondi-tionalprobabilityofcoreblockageduetoboronofzero.Please explainiftheRELAP5calculationshowingadequatecorecooling underthisscenarioaccountsforthemostlimitingmedium-break LOCA(breaksize/location)andifitisconsistentwithaccident sequencemodeling(i.e.,modelsonlyonetrainofECCS).There-sponseshouldaddressallGSI-191accidentsequencesthatused RELAP5simulations.RemovedResponse,Pg.242(c)RELAP5simulationsareusedtosupporttheconclusionthatadequatecorecoolingisachievedforsomeLOCAsevenunderthe assumptionofcompletecoreblockage.Pleasedescribehowthese simulationsaccountedforthereductionincladding-to-coolant heattransferthatwascalculatedbytheLOCADMcomputer code,asdescribedinVolume3,Section5.10.1.

RequiredResponse,Pg.2423.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume3,Section4.2,StructuredTuesday1 stMarch,2016:19:32,Page41of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONInformationProcessFlow,describesthequanti"cationofnetposi-tivesuctionhead(NPSH)marginandcoreblockageasafunctionof time.Accordingtothissection,time-dependentvaluesarecompared againstacceptancecriteriafrom t=0(i.e.,timethattheLOCAoccurs)and t=30days.Thisappearstocon"ictwithVolume3,as-sumptionm,whichstatesthatitwasassumedthata36-hrruntime fortheCASAGrandesimulationsissttopredictthescenarios thatwouldproceedtofailure.(a)PleaseclarifytheaccidentdurationusedbyCASAGrandetocalculatetheconditionalprobabilityofsumpandcoreblockage.

Also,identifyallotheranalysesperformedoutsideofCASAGrande (e.g.,time-dependentcoatingsfailure)andtheirassumedacci-dentduration.RemovedResponse,Pg.243(b)ManyofthesimulationsperformedbyCASAGrandeconcludedthatnoneofthesevenperformancethresholdsidenti"edinVol-ume1,Section2.3.5,LOCAModels,wereexceeded.Forthese cases,pleasestateifananalysiswasperformedtocon"rmthat attheendofeachsimulation,theplantwasinasafe,stable endstate.Forexample,pleaseexplainifanycasesweretrending towardaperformancethresholdwhenthesimulationwaster-minated.Ifso,pleaseprovidejusti"cationthattheselectedacci-dentdurationwasappropriatetocaptureallphysicalphenomena (e.g.,long-termchemicalIffailuresduetoGSI-191phe-nomenacouldoccuraftertheCASAGrandeanalysisduration, pleaseexplainhowwasthiswasconsideredinthePRAmodel (noteSupportingRequirementSC-A5intheASME/ANSPRA

Standard).RemovedResponse,Pg.244(c)Pleasestatewhatplantconditionsandcon"gurationisassumedforthesafe,stableendstateinthePRAmodel.Pleasedescribe.

RequiredResponse,Pg.244(d)PleaseexplainwhethertheconditionalprobabilitiescalculatedbyCASAGrandewereadjustedinanywaytomatchthePRA missiontimeof24hours.RemovedResponse,Pg.245

• HumanReliabilityAnalysis1.RG1.174,Sections2.3.1,Scope,and2.3.2,LevelofDetailRe-quiredtoSupportanApplication,statethatthescopeandlevel ofdetailofthePRAmodelmustbesttomodeltheimpact oftheproposedchange.Assumption3.cinVolume3statesthat isolablebreakscanbeexcludedfromtheevaluationsinceisolable breakswouldnotleadtorecirculation.Pleaseexplainthebasisfor thisassumption.Pleasedescribewhathumanerrorprobabilitywas usedforthefailuretoisolateanisolablebreak.Pleasestatewhether thereareanyisolablebreaksthatcould,ifnotisolated,resultinthe needtoentertheECCSrecirculationmode.RemovedResponse,Pg.1202.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheTuesday1 stMarch,2016:19:32,Page42of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproposedchange.Undercertainconditions,operatoractionsrequiredtostartorsecurethepumpsmaydependontheofthedebris generatedbythespeci"cpipebreak.PleasedescribeifCASAGrande considersthepotentialforthenumberofrunningpumpstochange duringascenariobecauseofoperatoractionstakeninresponseto cuesthatdebrisisbuildinguponthesump.RemovedResponse,Pg.1213.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactofthe proposedchange.Volume2describestwotopeventsthatmodeloper-atoractionsusedtosecurecontainmentspray.TopeventOSI(page 77)representsashort-termactiontosecureonetrainofcontainment spraypriortorecirculation,giventhatallthreetrainsareavailable.

TopeventOFFS(page83)representsalonger-termactiontosecure alltrainsofcontainmentsprayoncecontainmentpressureandiodine levelsaresuitablylow,theseareconditionsthatmayoccurafterre-circulationisestablished.Accordingtotheirdescriptions,thesetop eventsarealwaysassumedsuccessfulwhendeterminingthefailure probabilitiesintroducedbytheGSI-191phenomena.Pleaseprovide thefollowinginformation:(a)PleasestateiftheCASAGrandemodelstheplantconditions(e.g.,sump"owrates,washdownrates,refuelingwaterstorage tank(RWST)drain-downtimes,etc.)thatwouldoccurifthree containmentspraytrainswererunning(i.e.,ifthemanualactions modeledbytopeventOSIareunsuccessful.)RemovedResponse,Pg.245(b)PleasestateiftheCASAGrandemodelstheplantconditions(e.g.,sump"owrates,washdownrates,RWSTdrain-downtimes, etc.)thatwouldoccuriftheoperatorsfailtosecurecontainment spraylongtermoncecontainmentpressureandiodinelevelsare suitablylow(i.e.,themanualactionsassociatedwithOFFSare

unsuccessful).RemovedResponse,Pg.245(c)Iftheanswertoeither(a)or(b)isno,pleaseprovideatechnicalbasisandexplainhowthePRAmeetstheASMEHLR-HR-G requirementtoperformanassessmentofpost-initiatorhuman failureeventsusingawell-de"nedandself-consistentprocessthat addressesscenario-speci"cin"uencesonhumanperformance.RemovedResponse,Pg.2464.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume2,page85statesthattheprobabilityofexcessboronprecip-itation(topeventBORON)dependsonthreefactors:(1)whether thebreakisinthecoldleg;(2)theextentofcore"owblockageprior tohot-legswitchover;and,(3)whetheralowheadsafetyinjection (LHSI)trainisrealignedforhot-legrecirculation.(a)PleaseprovidetheprobabilityassignedtoBORONforeachcom-binationofthesethreefactorsusedinthePRAmodel.Atable orgraphicmaybeausefulwaytoprovidethisinformation.RemovedResponse,Pg.121(b)Assumption1.jinVolume3(page72of248)statesthatswitchovertohotleginjection(factor3)isassumedtooccurbetween5.75Tuesday1 stMarch,2016:19:32,Page43of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONand6hoursafterthestartoftheevent.Pleasedescribehowthehumanerrorprobabilities(HEPs)associatedwiththistopevent (HLEG)weredevelopedandhowtheyaccountforLOCAsize andplantcon"guration(e.g.,numberofpumpsavailable,impact ofdebris,etc.),aswellasfactors1and2de"nedabove.RemovedResponse,Pg.1225.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Onpage32ofVolume3,otherimportantlonger-termactionsare listed,whichinclude:(1)Securingonecontainmentspraypumpifall threecontainmentspraypumpsaresuccessfullyinitiated;(2)Secur-ingallcontainmentspraypumpslaterintheevent;(3)Switchover toECCSsumprecirculationaftertheRWST[refuelingwaterstorage tank]hasbeendrained;and(4)Switchovertohotleginjection.Please explainhowtheCASAGranderesultsweredevelopedtoaddressthe variouscombinationsofsuccessandfailureoftheseoperatoractions.

PleasealsoexplainhowtheconsistencybetweentheactualPRAsce-narioandtheGSI-191basiceventfailureprobabilitiesdevelopedin CASAGrandewasassured.RemovedResponse,Pg.1806.RG1.174,Section2.5.5,ComparisonwithAcceptanceGuidelines,statesthatcareshouldbetakentoensurethattherearenounquan-ti"eddetrimentalimpactstoproposedchanges,suchasanincrease inoperatorburden.SectionC.5.8,MitigationofInadequateReactor CoreFlow,ofAppendixCtoVolume1listsanumberofopera-toractionsassociatedwithdebris.Foroperatoractionsthatapplyin boththeGSI-191PRAbasecasemodelandtheGSI-191PRAdebris model,pleaseexplainhoweachoperatoractionsHEPwasmodi"ed asaresultofdebrisconsistentwithASMEHLR-HR-G,whichstates thatscenario-speci"cin"uencesonhumanperformanceshouldbead-

dressed.RemovedResponse,Pg.124

• PRAScope1.Aseismiceventmaypotentiallydislodgeandtransportinsulationtothecontainmentsump.AnysubsequentsequenceofeventsthatleadstorecirculationfromtheECCSsumpcouldbeadverselyimpacted bydebris.RG1.174,Section2.3.1statesthatthescopeofthePRA modelmustbesttomodeltheimpactoftheproposedchange.

Pleaseidentifysuchaccidentsequencesandestimatetheincreasein coredamageandlargeearlyreleasefrequenciesduetoaseismicevent asaresultofhavingdebrissourcesinthecontainment.

RequiredResponse,Pg.1252.Volume2(page47of257)states,inpart,that...amediumLOCAononeprimaryloopwouldbeassumed.tobeaccompaniedbymediumLOCAonallotherloops.The resultisthatseismicallyinducedmediumandlargeLOCAs aremodeledasbeingexcessiveLOCAs-whichhavenosuccess sequencesbyde"nition.Tuesday1 stMarch,2016:19:32,Page44of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactof theproposedchange.Whileitisacommonassumptionthatseismic failuresamonglikecomponentsare100percentcorrelated,forthis analysisthisassumptionleadstoalowercalculatedvalueofdelta risk.Thatis,forcaseswhereasinglelargepipefailsduetoaseismic initiatingevent,orwheremultiplesmallborepipesfail,itmightbe possibletomitigatethescenariotoagreaterextentifdebrissources donotexistinsidecontainment.Pleasejustifynotanalyzingtheaddi-tionalriskofGSI-191phenomenaforseismiceventswithoutreliance ontheconservativeassumptionof100percentcorrelation.

RequiredResponse,Pg.2461.3.1.2RESULTSINTERPRETATION

• Quanti"cation1.Volume2,page3states,inpart,thatThechangeincoredamagefrequencyandlargeearlyreleasefrequencyisdeterminedbycomparingtheresultsoftwomod-els:onewithnosourcematerialinthecontainmentcapable ofproducinganyGSI-191ctsandonerepresentingthe currentplantconditionsthatincludesboth"brousinsulation thatmightbeliberatedfollowingaLOCAandlatentmaterial foundinthecontainment.Also,elsewhereinthesubmittal,itsaysfailurebranchesarenotincludedsincetheyleadtocoredamagewithorwithoutdebris.This wouldimplythattheanalysisproducedthedeltariskdirectlyby consideringsuccessbranchesthatwouldbeimpactedbydebris, withouttheneedtosubtractabase-caserisk.Itisimportantthat theNRCunderstandhowtheriskwascalculated.RG1.174 Section2.2statesthatthelicenseeshouldassesstheexpectedchange inCDFandLERF.Pleaseprovidethefollowing:(a)PleaseclarifywhethertheCDFandLERFwerecalculatedbysummingonlytheformersuccessstatesthatgotocoredamage duetoGSI-191phenomenaorbyrequantifyingtheentiredebris modelandsubtractingthebasecase.RemovedResponse,Pg.126(b)PleaseexplainifthesameLOCAinitiatingeventfrequenciesandparameteruncertaintydistributionswereusedforboththebase-lineanddebrismodels.RemovedResponse,Pg.1262.Pleaseprovidealistofthetop100accidentsequencesthatresultincoredamageduetooneofthesevenfailuremechanismsidenti-

"edinVolume1;thatis,includeonlysequencesthatincludefailure ofrecirculationcoredamageresultingfromasaresultofGSI-191

phenomena.RemovedResponse,Pg.126

• UncertaintyAnalysisTuesday1 stMarch,2016:19:32,Page45of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.RG1.200de"nesmodeluncertaintyasanissuewherenoconsensusapproachormodelexistsandwherethechoiceofapproachormodelis knowntohaveanonthePRA(e.g.,introductionofanewbasic event,changestobasiceventprobabilities,changesinsuccesscrite-ria,introductionofanewinitiatingevent.).Volume1Section2.5.3, ModelUncertainty,containsageneraldiscussionofmodeluncer-tainty(usingchemicalanddebris"ltrationasexamples)and broadlystatesthatconservatismwasusedtoaddressmodeluncer-tainty.ThisisinconsistentwithRG1.200,Section3.3.2,Assessment ofAssumptionsandApproximations(andASMEHLR-QU-E)guid-ancethatstatesthatallsourcesofmodeluncertaintyshouldbeiden-ti"edandtheironthePRA(asidenti"edabove)shouldbede-terminedasdiscussedinRG1.174,Section2.5.5.Uncertaintymustbe evaluatedforthisanalysis,includingthePRAmodel,CASAGrande, andanysupportinganalyses.Pleaseprovidethefollowinginforma-

tion:(a)Pleaseidentifyallsourcesofkeymodeluncertaintyasde"nedbyRG1.200.RequiredResponse,Pg.246(b)Pleaseidentifythekeyassumptionsasde"nedbyRG1.200.

RequiredResponse,Pg.246(c)Pleasedescribethepotentialofthekeyassumptionsontheresultsofthisstudy;thatis,ontheCDFandLERFattributable toGSI-191phenomena.Describetheresultsofanyrelatedsen-sitivityanalysesthatwereperformed.

RequiredResponse,Pg.2472.Volume3,Assumption3.a(page76of248)statesthatthegeometric-meanaggregationofLOCAfrequenciesinNUREG-1829isthemost appropriatesetofresultstouseforthisevaluation.Thebasispro-videdisthatgeometric-meanaggregationproducesfrequencyesti-matesthatareapproximatelythesameasthemedianestimatesof thepanelists.Thereisnojusti"cationaboutwhythemedianesti-mateispreferredandemphasisonthemediancon"ictswiththeRG 1.174guidancethatthemeanvaluesbeusedfordecision-making.Fur-thermore,informationinNUREG-1829,Section7.6.4,Aggregation, showsthattheuseofthearithmeticmeaninsteadofthegeometric meanwouldincreasetheLOCAfrequencybyanorderofmagnitude ormoreforsomeLOCAcategoriesandmaythereforesubstantially increasetheriskestimates.Consequently,selectionofthegeometric meanisakeyassumptionandselectionofthearithmeticmeanrep-resentsanalternativereasonableassumptionasde"nedbyRG1.200.

ThisissupportedbyRG1.174,Section2.5,ComparisonofProb-abilisticRiskAssessmentResultswiththeAcceptanceGuidelines, whichstates,inpart,thatthelicenseeshould[identify]keyassump-tionsinthePRAthatimpacttheapplication.Sensitivitystudies provideimportantinformationabouthowsomeofthekeyassump-tionsthe"nalresultsasdiscussedinRG1.174Section2.5.3.

PleaseprovideCDF,LERF,andusingthearith-meticmeanaggregationofLOCAfrequenciesinNUREG-1829.

RequiredResponse,Pg.1563.Volume1,Section1.3.1,LOCAFrequency,statesthatLOCAfre-Tuesday1 stMarch,2016:19:32,Page46of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONquencieswereobtainedfromTable7.19ofNUREG-1829for25yearsoperation.Furthermore,assumption3.binVolume3(page76)states thatcurrent-dayLOCAfrequenciesaremoreappropriatetousefor thisevaluationthantheend-of-plant-licensefrequencies.RG1.174, Section2.5.5statesthatitisincumbentonthelicenseetodemonstrate thatthechoiceofreasonablealternativehypotheses,adjustmentfac-tors,ormodelingapproximationsormethodstothoseadoptedinthe PRAmodelwouldnotsigni"cantlychangetheassessment.Also,itis assumedthattheSTPplantswillcontinuetooperateformorethan 25years;RG1.174Section3,Element3:De"neImplementationand MonitoringProgram,statesthatthelicenseeshouldde"neanim-plementationandmonitoringprogramtoensurethatnounexpected adversesafetydegradationoccursdotothechange.Pleasejustify theuseofthe25-yearfrequencyestimatesratherthanthe40-year estimatesprovidedbyNUREG-1829.PleaseprovideCDF,LERF, andusingthe40-yearestimates.

RequiredResponse,Pg.2474.TheacceptanceguidelinesofRG1.174,Section2.5.5arede"nedsuchthattheappropriatemeasureforcomparisonisthemeanvalue oftheuncertaintydistributiononthecorrespondingmetric.Typi-cally,statisticalsamplingsimulationswilldeveloprandomvariables thatpreservethemeanofthedistributionfromwhichthevariables aresampled.STPhaschosento"taJohnsonboundeddistribution thatmatchestheexpert-provided5th,50th,and95thpercentilesin NUREG-1829,butdoesnotmatchthemeanvalues.Theproperties ofthedistributionaresuchthat,as"t,themeanofthe"tteddistri-butionisalwayslessthantheexpertsmeansfromthedistributions inNUREG-1829.(a)PleaseexplainwhytheSTPevaluationdepartsfromtheregula-torypositioninRG1.174regardingtheuseofmeanvalues.RemovedResponse,Pg.248(b)TheJohnson"tto5th,50th,and95thpercentilesisnotunique.Alternativeaccurate"tscanbeconstructedwitharbitraryval-uesofthescaleparameterA.ThescaleparameterAde"nesa boundonthemaximalfrequenciessampledintheMonteCarlo model.ByincreasingthevalueofA,therelativeproportionof largetomediumtosmallbreakscanbealtered,especiallyinthe extrapolationrangebeyondthe95thpercentile.Pleaseprovidea technicaljusti"cationfortheselectionofthescaleparameterA (otherselectionsappearpossiblethatcouldchangetheoutputs byCASAGrande).RemovedResponse,Pg.248(c)PleaseprovidethemaximumexpectedbetweentheCDF,LERF,anddevelopedfromboundedJohn-sondistributionsthatconsideralternativevaluesofthescalepa-rameterA,andotherdistributionsthatwouldpreservemeanval-uesreportedinNUREG-1829.Note,inparticular,thatalterna-tiveboundedJohnsondistributionswithlargevaluesofthescale parameterAcanbebuilttoaccurately"ttheNUREG-18295th, 50th,and95thpercentiles,andproducemeanestimatesclosertoTuesday1 stMarch,2016:19:32,Page47of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtheNUREG-1829valuesthancurrent"tsusedbySTP.RemovedResponse,Pg.249(d)InTable8.4-1inVolume2,LOCAexceedancefrequenciesaretabulatedfortbreaksizesthatareconsistentwithmod-i"edboundedJohnsondistributions(themodi"edJohnsonisa scaledboundedJohnsonplusauniformdistribution)designedto matchNUREG-1829meanvalues.The"ttothe5th,50th,and95thNUREG-1829percentilesofthesemodi"edJohnsondistri-butionsdoesnotappeartobeaccurate.Therefore,thesemod-i"edJohnsondistributionsinferredfromTable8.4-1appearto betthantheboundedJohnsondistributionssummarized inTable2.2.2inVolume4d.Pleasejustifytheapparentuseof tboundedJohnsondistributionsinthePRAandCASA

Grande.RemovedResponse,Pg.2495.Volume2,page6states,inpart,thattheLOCAfrequencyuncer-taintiessampledinthePRAuncertaintyanalysisareassumedinde-pendentoftheprobabilitiesoffailurefromtheuncertaintyanalysis ofCASGrande.Thisassumptiondoesnotaccountforthestateof knowledgecorrelationbecausethePRAandCASAGranderelyon thesameparameterfortheirquanti"cation(LOCAfrequencyde-rivedfromNUREG-1829).RG1.174,Section2.5.2,ParameterUn-certainty,statesthatthestateofknowledgecorrelationshouldbeac-countedforunlessitcanbeshowntobeunimportant.Therefore,you arerequestedtoeithercalculateCDF,LERF,and accountingforthestate-of-knowledgecorrelationordemonstratethat itisunimportanttothisapplication.RemovedResponse,Pg.2496.RG1.174Section2.5.5statesthatitisincumbentonthelicenseetodemonstratethatthechoiceofreasonablealternativehypotheses, adjustmentfactors,ormodelingapproximationsormethodstothose adoptedinthePRAmodelwouldnotsigni"cantlychangetheas-sessment.Thisdemonstrationcantaketheformofwell-formulated sensitivitystudiesorqualitativearguments.Ingeneral,theresultsof thesensitivitystudiesshouldcon"rmthattheriskacceptanceguide-linesarestillmetevenunderalternativeassumptions.Pleaseprovidetheresultsofanaggregateanalysisthatquanti"estheintegratedimpactonCDF,LERF,andfromall sensitivitystudiesthatwereperformed.Inthisaggregateanalysis, forthosecaseswhereindividualassumptionshaveasynergisticef-fectontheresults,asimultaneousanalysisshouldbeperformed.For thosecaseswherenosynergyexists,aone-at-a-timeanalysismaybe t.RemovedResponse,Pg.2491.3.2ARCB:RadiationProtection&ConsequenceBranch1.Inantoensureacompleteandaccuratereviewofthedosecon-sequenceanalyses,pleaseprovideadditionalinformationintabularform describing,foreachdesignbasisaccidentbytheproposedRisk InformedGSI-191submittal,allthebasicparametersusedinthedoseTuesday1 stMarch,2016:19:32,Page48of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONconsequenceanalyses.Foreachparameter,pleaseindicatethecurrentli-censingbasis(CLB)value,therevisedGSI-191valuewhereapplicable,as wellasthebasisforanychangestotheCLB.Anexampleoftheinput/as-sumptionsneededisprovidedinTable4.3-11DoseAnalysisInputsfor LOCAprovidedinSTPsalternatesourceterm(AST)submittaldated March22,2007(ADAMSAccessionNo.ML070890474).TheNRC requeststhattheinformationincludeallofthebasicparameterswhether ornottheindividualparameterisbeingchangedfortheGSI-191amend-ment.TheNRCalsorequeststhattheinformationbepresentedin separatetablesforeachaccident(i.e.,LOCA,thefuelhanding accident(FHA),themainsteamlinebreakaccident(MSLB),thesteam generatortuberuptureaccident(SGTR),thecontrolrodejectionaccident (CREA),andthelockedrotoraccident(LRA)).

RequiredResponse,Pg.2512.STPidenti"edthefollowingconditionrelatedtotheASTsubmittal:WestinghouseElectricCompanyNuclearSafetyAdvisoryLetter(NSAL)-06-15,datedDecember13,2006,advisedoperatorsofWestinghouseplants thatthesingle-failurescenariofortheSGTRanalysisthatlicenseesused intheiraccidentanalysismaynotbelimiting.AsstatedintheSTP ASTNRCSafetyEvaluationdatedMarch6,2008(ADAMSAccessionNo.

ML080160013),ThelicenseehasevaluatedtheapplicabilityofNSAL 15againsttheaccidentanalysisassumptionsandhasdeterminedthatthe currentsingle-failureassumptionfortheSTPSGTRanalysisisnotlim-iting.Therefore,thelicenseeisoperatingundercompensatorymeasures tomeetregulatorydoseguidelines.Thelicenseeplanstoresolvethiscon-ditionattheearliestopportunitysothattheassumptions,includingthe limitingsinglefailure,fortheSGTRaccidentanalysisdescribedhereinare consistentwiththeplantresponsetothisevent.Tosupportthelimiting single-failureassumptionsintheSGTRanalysis,STPwillmaintainan administrativelimitforreactorcoolantsystem(RCS)doseequivalentio-dine131(DEI)sothattheradiologicaldosereferencevaluesfortheSGTR analysisremainbounding,andthelicenseewillcontinuetocomplywith GOG[GeneralDesignCriteria]19.Pleasestateifthisconditionbeenresolved?Ifso,pleasedescribehow?Also,pleaseprovidejusti"cationthatGOG19continuestobemet.

RequiredResponse,Pg.2513.TheLOCAanalysisassumesthatiodinewillberemovedfromthecontain-mentatmospherebycontainmentsprayandnaturaltothecon-tainmentwalls.Asaresultoftheseremovalmechanismsalargefractionof thereleasedactivitywillbedepositedinthecontainmentsump.Thesump waterwillretainsolublegasesandsoluble"ssionproductssuchasiodines andcesium,butnotnoblegases.TheguidancefromRG1.183,Alternate RadiologicalSourceTermsforEvaluatingDesignBasisAccidentsatNu-clearPowerReactors,July2000(ADAMSAccessionNo.ML003716792),

speci"esthattheiodinedepositedinthesumpwatercanbeassumedto remaininsolutionaslongasthecontainmentsumppHismaintainedat orabove7.TheASTapplicationindicates:Tuesday1 stMarch,2016:19:32,Page49of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONAfterthe"rstday,thecontainmentsumppHwillbegintodecrease,reach-ing6.8bytheendofthe30-daydurationoftheradiologicalconsequence analysisfortheDesignBasisAccident(DBA)LOCA,andtheimpactof thatdecreasehasbeenre"ectedintheControlRoomanddoses.ItisnotedthattheASTapplicationfurtherindicates:ThedesigninputsforcalculatingthecontainmentsumppoolpHwereconservativelyestab-lishedbythelicenseetomaximizetheacidiccontributiontosumppHand minimizethebasiccontribution.TheGSI-191applicationindicatesthepossibilitythatdebrisgeneratedduringaLOCAcouldclogthecontainmentsumpstrainersinpressurized-waterreactors(PWRs)andresultinlossofNPSHfortheEGGSandCSS

[containmentspraysystem]pumps,impedingthe"owofwaterfromthe

sump.Pleasediscusstheexemptionjusti"cationastheyrelatetotheeonsumpwaterpH,radiologicalconsequences,andlossofthecontainment spraysystem(CSS).

RequiredResponse,Pg.2511.3.3EMCB:MechanicalandCivilEngineeringBranch1.Intheapplication,thelicenseeprovidedaqualitativeresponseregardingthestructuralanalysiswithoutanysupportingquantitativedata.Without actualandallowablestressesanddesignmarginsforthevariouscompo-nentsofthesumpstrainerstructuralassembly,theNRCisunableto makeadeterminationabouttheinherentlevelofconservatismemployedin thedesign.Thisinformationwasnotprovidedinthelicenseesrecentsub-mittalsconcerningGenericLetter(GL)2004-02,PotentialImpactofDe-brisBlockageonEmergencyRecirculationduringDesignBasisAccidents atPressurized-WaterReactors,(ADAMSAccessionNo.ML042360586).Pleasesummarizethestructuralquali"cationresults,includingtheactualandallowablestresses,anddesignmarginsforthevariouscomponentsof thesumpstrainerstructuralassembly.

RequiredResponse,Pg.251 2.ResponsetoEMCBFollow-upRAIdatedJune2,2014ByletterdatedDe-cember23,2013(AgencywideDocumentsAccessandmanagementSystem (ADAMS)AccessionNo.ML14015A312,STPNuclearOperatingCom-pany(STPNOC)providedresponsetotheU.S.NuclearRegulatoryCom-mission(NRC)questionSTP-GSI-191-EMCBRAI-1.Inresponsetothe NRCquestion,STPNOCprovidedinteractionratios(IRs)forvari-ouscomponentsofthestrainerassemblyfortwoloadcases.AlloftheIRs werebelowone,indicatingallapplicabledesigncoderequirementswere satis"ed,bymaintainingactualstressesandloadslessthantheallowable values.However,itisuncleartotheNRCwhattialpressures theanalyzedloadcasesrepresentandhowtheyrelatetothe5.71feet(ft.)

and9.35ft.ofequivalentheadlossdiscussedinsubmittaldatedNovember 13,2013((ADAMSAccessionNo.ML13323A183).Inaddition,therisk-informedsubmittalnotedthatstrainerstructuralfailurewasapossible failuremode.Thisappearstoindicatethatthereareloadingconditions wheretheIRvalueswouldbegreaterthan1andthestrainercouldfail.Tuesday1 stMarch,2016:19:32,Page50of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONHowever,Section6.2.2.2.3ofAttachment2toEnclosure3ofsubmittaldatedNovember13,2013states,Thesumpstructuresaredesignedto withstandthemaximumexpectedtialpressureimposedbytheac-cumulationofdebris.PleaseidentifythetialpressureorequivalentheadlossassociatedwiththetwoloadcasesprovidedinletterdatedDecember23,2013,in responsetotheRAIquestion.Pleaseexplainifthereareconditionswhich couldloadthestrainersbeyondthemaximumtialpressurefor whichtheyarequali"ed.RevisetheabovestatementfromSection6.2.2.2.3, asnecessary,basedonyourresponse.

RequiredResponse,Pg.2521.3.4EPNB:ComponentPerformance,NDEandTestingBranchTheNRChasreviewedtheLOCAfrequencyestimatesinSections2.2.3,LOCAFrequencies,and5.3,LOCAFrequency,ofVolume3andrequests thefollowingadditionalinformation.1.Volume3,Section5.3.1,RelativeWeightofBreaksinSpeci"cWeldCat-egories,page125,speci"esthedegradationmechanismsthatwereconsid-eredintheLOCAfrequencyestimates.Therisk-informedinserviceinspec-tion(RI-ISI)programatSTPwasbasedonEPRITR-112657,Revised Risk-InformedlnserviceInspectionEvaluationProcedure(PWRMRP-05),"

RevisionB-A,FinalReport,December1999(ADAMSAccessionNo.ML013470102).TheNRCnotesadiscrepancyinthedegradationmecha-nismsusedbetweentheRI-ISIprogramandtheGSI-191submittal.Several ofthedegradationmechanismsinTable2-2ofEPRITR-112657report thatareusedintheRI-ISIprogramarenotlistedasthedegradation mechanismsintheGSI-191calculations.Forexample,erosioncavitation, corrosionfatigue,corrosionattack,andwaterhammeridenti"edinTable 2-2oftheEPRIreportarenotconsideredinSection5.3.1.Pleasediscuss thediscrepancy.RemovedResponse,Pg.2522.Volume3,Section5.3.1,page125,statesthatTable5.3.1,Category68,containstwoweldsizes(nominal0.75-inchand1-inchpipes).However, Table2.2.6,Category68showsonly1-inchweldsize.Pleasediscusshow theLOCAfrequencycalculationshandlethisdiscrepancy.Thatis,please discusswhethertheinitiatingfrequencycalculationincludesthefrequen-ciesfromthe0.75-inchand1-inchpipesizesoronlythe1-inchpipesize isused.ThisdiscrepancyalsoappliestoCategories6Aand8Cwhichalso containtwoweldsizes.RemovedResponse,Pg.2533.PleasediscusswhetherweldsevaluatedintheGSI-191analysiscontain"awswhileinservice.Ifyes,pleasediscusswhethertheLOCAfrequencies fortheseweldsareincreasedfromthatofNUREG-1829estimates.Ifthe pipefailureprobabilitiesfortheseweldsarenotincreased,pleaseprovide justi"cations.Volume3,Table5.3.1,page126showsthatfourweldsat thepressurizerwereweldoverlaid.Pleasediscusswhetherthepipefailure probabilityLOCAfrequenciesforthesemitigatedweldswerereducedfrom thefrequencyestimatesofNUREG-1829.Ifnot,pleaseprovidejusti"ca-

tions.RemovedResponse,Pg.253Tuesday1 stMarch,2016:19:32,Page51of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION4.Title10oftheCodeofFederalRegulations(10CFR),Part50,50.55a(g)(6)(ii)(F)incorporatesbyreferenceAmericanSocietyofMechanicalEngineersBoiler andPressureVesselCode(ASMECode)CaseN-770-1,AlternativeEx-aminationRequirementsandAcceptanceStandardsforClass1PWRPip-ingandVesselNozzleButtWeldsFabricatedwithUNSN06082orUNS W86182WeldFillerMaterialWithorWithoutApplicationofListedMit-igationActivities,SectionXI,Division1,withconditions.ASMECode CaseN-770-1requireslicenseestoperformaugmentedinspectionsbeyond thosethatarerequiredbytheASMECode,SectionXI,forpipingwith Alloy82/182dissimilarbuttwelds.Pleasediscusswhetherperiodicinspec-tionsperASMECodeCaseN-770-1wouldreducetheLOCAfrequency estimationfortheAlloy82/182dissimilarmetalwelds.Ifyes,pleasedis-cusshowmuchLOCAfrequencyestimateswerereducedforthesewelds.RemovedResponse,Pg.2545.Volume3,Section5.3.5,SampleBreakSizesatEachWeldLocation,page149,discusseshowthebreaksizesareselectedtoderivetheLOCA frequencyestimates.Figure5.3.4,page151,providestheselectedbreak sizesforweldcase1Basanexample.(a)Figure5.3.4presentsatotal of13breaksbeingsimulatedateachweldbelongingtoWeldCase1B (10largebreaks,twomediumbreaksandonesmallbreak).However,in Table2.2.3,underweldcase1B,theNRC"ndsonly12breaks.Please explainhow13breakswereidenti"ed.(b)Pleasediscusshowthebreaksize distributionschemeinFigure5.3.4providescon"denceandassurancethat thebreakselectionwillresultinappropriatedebrisgenerationasthereare manypossiblescenariosforthebreaksizedistribution.Thebreaksizes couldbeevenlydistributedsuchthattherearefoursmallbreaks,four mediumbreaksandfourlargebreaks(assumingthetotalbreaksare12).

Thebreaksizescouldbedistributedskewedtothesmallsize,suchas10 smallbreaks,onemediumbreakandonelargebreak.Thebreaksizecould alsobeskewedtowardmediumbreakssuchasonesmallbreak,10medium breaks,andonelargebreak.Pleasediscusshowitwasdeterminedthatthe breaksizedistributionintheCASAGrandeanalysisisappropriate(i.e.,

neithertooconservativenortoonon-conservativeintermsofthedebris generation)whenexaminingthe"nalprobabilityresult(thecoremelt

frequency).RemovedResponse,Pg.2546.ByletterdatedSeptember10,2012,theNRCapprovedtherisk-informedinserviceinspection(RI-ISI)programforthethird10-yearinserviceinspec-tionintervalatSTP,Units1and2(ADAMSAccessionNo.ML12243A343).

Pleasediscussthefollowing:(a)PleasestateiftheLOCAfrequencyestimatesusedforweldsintheGSI-191submittalareconsistentwiththeLOCAfrequencyestimates usedintheRI-ISIprogram.Ifthecomparisonisappropriate,please providenumericalexamplesofthecomparison.Ifthecomparisonis notappropriate,pleaseprovideexplanation.

RequiredResponse,Pg.255(b)IftheLOCAfrequenciesforweldsarenotconsistentbetweenthetwoanalyses,(1)pleaseidentifytheandexplainwhythere areand(2)pleasediscusswhytheLOCAfrequenciesTuesday1 stMarch,2016:19:32,Page52of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproposedintheGSI-191submittalareacceptableiftheyarenotconsistentwiththatoftheRI-ISIprogram.

RequiredResponse,Pg.2551.3.5ESGB:SteamGeneratorTubeIntegrityandChemicalEngi-neeringBranch1.3.5.1Chemical1.Theexponentialprobabilitydensityfunctions(PDF)forsmall-,medium-,andlarge-breakLOCAs(e.g.,Figure5.6.4,Volume3)areshowninterms ofachemicalbump-upfactor.TheNRChasquestionsrelatedtothe conventional(non-chemical)headlosscorrelation.Thereviewofachemical bump-upfactoriscomplicatedbythefactthatitisessentiallyamultiplier onaparameterthatisconcurrentlybeingreviewedforadequacy.Please providethefollowingadditionalinformation.(a)CASAGrandecalculatestheconventionalheadlossvalueforagivenbreakandthenappliesachemicalbump-upfactorindependentof theconventionalheadloss.Pleasejustifynotcorrelatingthechemi-calbumpupfactortotheconventionalheadlosssincethesamedebris bedbothvalues.BasedontheNRCsexperienceobserv-ingtesting,headlossforagivenquantityofchemicalprecipitates shouldberelatedtoboththetypeofprecipitateandthe"ltering characteristicsofthedebrisbed.RemovedResponse,Pg.256(b)InordertohelptheNRCjudgethemagnitudeofthechemicalheadlossbump-upfactor,pleaseprovide,byperformingrealizations fortheexistingCASAGrandemodel,arelativefrequencyplotof chemicalforSTPintermsofabsoluteunits(e.g.,feetofwa-ter)forthesmall-breakLOCA(SBLOCA),medium-breakLOCA (MBLOCA),andlarge-breakLOCA(LBLOCA).Forexample,ahis-togramshowingchemicalheadloss(feet)onthex-axisandnumber ofoccurrencesonthey-axiswouldbeveryusefultotheRemovedResponse,Pg.257(c)PleaseprovideadditionaldetailsonhowtheresultsfromtheChemicalHeadLossExperiment(CHLE)testing,WCAP-16530-NP-A,"Eval-uationofPost-AccidentChemicalinContainmentSump FluidstoSupportGSI-191,"March2008(ADAMSAccessionNo.

ML081150379),calculations,andreasonableengineeringjudgment wereusedinthedevelopmentoftheexponentialPDF.Inaddition, pleasesupplythebasisforchoosingtheexponentialformofthePDF overothers(e.g.,Weibull).RemovedResponse,Pg.257(d)PleaseprovideadetailedtechnicalbasisforthemeanbumpupfactorsshownfortheSBLOCA,MBLOCA,andLBLOCA.TheNRC hasobservedheadlosstestingwherethegreatestchemicalbump-up factorsareassociatedwiththinnerbeds.Pleasediscusswhythemean bumpupfactorwouldbehigherforaLBLOCA.Pleaseexplainifit ismoreprobablethatadebrisbedforsmallerandmediumbreaks (assumingthebedcoveragecriterionismet)wouldconsistprimarily of"ber"nesthatarethemostreadilytransportabletothestrainer.

Ingeneral,"ner"berbedstendtoleadtogreaterheadloss.RemovedResponse,Pg.259Tuesday1 stMarch,2016:19:32,Page53of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION2.Pleaseexplainhowthehighestheadlossvalues(e.g.,90th,95thpercentile)obtainedusingCASAGrandecomparewiththeheadlossvaluesobtained fromtheSTPplant-speci"cstrainertestsatAldenLaboratory.Please discussbothintermsofconventionalheadloss(i.e.,beforeadditionof chemicalprecipitates)andafterchemicalprecipitateswereadded.Please discussallstrainertestresultsincludingthetestthatwasterminatedprior toadditionofprecipitates.RemovedResponse,Pg.2603.Pleaseprovidethetechnicalbasisforthe1E-05probabilityforthemaxi-mumchemicalforeachbreaksize.Theengineeringjudgmentused todeterminethatvalueappearstobearbitraryandotherexpertassessors couldeasilyreachdtconclusionsconcerningatailprobability.RemovedResponse,Pg.1814.Pleaseprovidetheresultsofasensitivitystudyrelatedtotheassumptionofthetailprobabilitythatshowshowdtassumptions(e.g.,1E-02,1E-03,1E-04)forthemaximumchemicalbump-uptailwouldthe probabilityofexceedingtheECCSpumpsNPSHcriteriaandtheimpact tothecoredamagefrequencyandlargeearlyreleasefrequency.Please evaluatethesetailprobabilitiesassumingtheconventionalheadlossis constantandequalto(a)0.5feet,(b)1.0feet,and(c)2feet.RemovedResponse,Pg.2615.SincetheSTPchemicaleevaluationisheavilydependentonengineer-ingjudgment,theNRCneedsclari"cationregardingthesensitivity ofvariousassumptionstotheoverallriskinformedevaluation.Inaddition tothesensitivitystudyrequestscontainedinotherchemicalRAis (e.g.,RAI#4),pleaseevaluatethekeychemicalareaassumptions (e.g.,bumpupfactors,typeofdistribution,etc.)andprovidesensitivity studiesthatwillhelpthetoevaluatehowchangesinthoseassump-tionswillaltertheprobabilityoffailures.Pleaseidentifyanyassumptions thatarecorrelatedandexplainhowthecorrelationwasconsideredinthe

analysis.RemovedResponse,Pg.2616.Pleasedescribetherelativechemicalcontributionsfromthesprayedma-terialscomparedtothesubmergedmaterials.Pleasestateifthechemical modelinputintoCASAassumesa"xed,6.5-hoursprayduration.Ifso, pleasediscusstheprobabilityofcontainmentsprayoperatingatatime beyond6.5hoursfollowingaLOCAandhowthechemicalanalysis wouldbechanged.Pleasedescribeifanysensitivitystudywasperformed onthespraytimewithrespecttohowitmaythechemicalsource term,theprobabilityofprecipitation,andultimatelytheGSI-191failure modes.RemovedResponse,Pg.2647.CHLETankTests3and4wereperformedwithexcessivequantitiesofaluminumrelativetotheplantandwithatemperaturepro"leintended toinducechemicalprecipitation.Thesetestsresultedinchemicalprecipi-tationandprovidedusefulinformationrelatedtoheadlossloopresponse tochemicalprecipitates.Theexistingtestsdonotappeartoaddressthe extentofdeviationfromthebestestimateplantconditionsthatcouldre-sultinchemicalprecipitation.Onepotentialmethodtoinformengineering judgmentwithrespecttochemicalprobabilitiescouldbeaseriesTuesday1 stMarch,2016:19:32,Page54of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONofsmallerscaletestsdesignedtoevaluatethethresholdconcentrationsofspeciesthatcouldresultinprecipitation.Forexample,testscouldbede-signedtoevaluatehowmuchaluminumorcalciuminsolutionwouldcause precipitationthatmayresultinsigni"cantincreasesinheadloss.These typesoftestswereincludedintheoriginalchemicaltestplansbut wereapparentlycancelled.Pleasediscussanyplansforsmallerscaletesting toinvestigatethresholdvaluesforprecipitationandwhetherthatinforma-tionwouldprovidegreatercon"denceindeterminingtheprobabilitythat apost-LOCAplantconditionwouldresultinchemicalprecipitateforma-tion.Iftherearenoplansforadditionaltests,pleaseprovidejusti"cation forthisengineeringjudgment.RemovedResponse,Pg.1828.TheSTPchemicalanalysisassumesnoprecipitationpriortothesumppoolcoolingto140degreesFahrenheitItispossible,however, toprecipitateacalciumphosphateprecipitateathighertemperaturesif tdissolvedcalciumispresent.PleaseexplainiftheCASAGrande modelincludescalciumsourcessuchasconcretedust,concreteablatedby thejet,andotherplantmaterialssuchasinsulation.Pleasestateifthere isapotentialforsomepipebreakstoproduceenoughcalciumsuchthat formationofaprecipitateatagreaterthan140temperatureshouldbe included.Sincesomeprecipitatescanformattemperaturesgreaterthan 140pleaseexplainhowincreasingthetemperaturethresholdinCasa Grandetheoutcomes.RemovedResponse,Pg.2659.Pleasedescribethekeysourcesofuncertainty(aleatoryandepistemic)associatedwiththedissolutionmodelandthesolubilitylimitsandhow isthisuncertaintyfactoredintotheprobabilitydensityfunctionsandthe chemicalbumpupfactors?RemovedResponse,Pg.26510.Thefollowingparametersdonotappeartobeconsideredinthesimpli"edapproachusedtoquantifychemicalforSTP:poolchemistry,pool pH,andtheamountsofaluminum,calcium,andzinc.Iftheseitemsare notconsidered,pleaseprovidejusti"cationforacceptabilityoftheanalysis withouttheirconsideration.RemovedResponse,Pg.26611.TheconclusionscontainedindocumentCHLE-014,T2LBLOCATestReport,"(letterdatedOctober13,2013,availableinADAMSAccession No.ML13323A873)state,inpart,Chemicalproductsdidformunderthe simulatedSTPLBLOCAconditionsbutprimarilywereadheredtothe galvanizedcoupons.Inaddition,CHLE-020,TestResultsfora10-day chemicaltestsimulatingLBLOCAconditions(T5),statesonpage 10,ThehighturbidityatthebeginningofTestsT5andT2shownin Figure3bmightbecausedbydetachmentofzincparticlesfromthezinc couponsandgalvanizedsteelcouponsduetothehightemperatureduring the"rst80minutesofthetest.Page75ofVolume6.2states,Althougha zinc(Zn)productwasobservedtoformunderSTPLOCAtestconditions, itwasnotincludedinthisanalysissincetheproductwasdetermined tobecrystallineandmainlyadheretostructureswithincontainmentas opposedtoreadilytravelwithsolution.Basedoninternationalexperience,Tuesday1 stMarch,2016:19:32,Page55of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONFramatomeANP,Inc.reporttitled,In"uenceofCorrosionProcessesontheProtectedSumpIntakeafterCoolantLossAccidents,December2006 (ADAMSAccessionNo.ML083510156),zinccorrosionproductdislodged byfallingwatercausedasigni"cantincreaseinheadloss,pleasediscuss:(a)IffollowingaLOCA,watereitherfallingfromapipebreakorfromotherlocationsinthecontainmentbuildingcoulddislodgezinccor-rosionproductfromgalvanizedsteelsurfacesthatcouldtransportto thestrainer.RemovedResponse,Pg.186(b)Whetherchemicalcontributionsfromzincshouldbeconsid-eredaspartoftheSTPchemicalanalysis.

RequiredResponse,Pg.18612.TheCHLEtestfacilityincludedthreeparallelverticalheadlossloopsthatwereintendedtoallowmultiplebedevaluationswitheachtest.Thetest resultssuggesttherewaspotentiallysomebiasinheadlossresultsbetween thethreeloops.Pleasedescribeanyevaluationsthatwereperformedand lessonslearned.Also,pleasedescribeanysigni"cantmodi"cationsthat weremadetothefacilityloopduringthecourseoftestingandhowthose modi"cationsmayhavetheresults.RemovedResponse,Pg.15713.ThealuminumsourceforCHLEtestswasaluminumremovedfromtheplant.Theswasdescribedinthetestdocuments(e.g.,

CHLE-012)asanon-homogenoussamplewithunknownconstituentsfrom yearsofusewhichremainedaftercleaning.DuringtheNRCsvisitto observeCHLEtesting,theobservedwhatappearedtobeagrout-like materialcoveringarelativelysmallportionofatestsample.Thesub-mergedssamplesweretakenfromthesideoftheand hadattextureandappearancethanthesamplescutforthevapor space.Analysisofunusedindicatedthepresenceofaluminum phosphateandaluminumoxide/hydroxidescales.Thepre-existingscale mayhavereducedthealuminumreleasedbycorrosion.Sincethecorrosion ofaluminumcanhaveasigni"cantimpactonwhetherchemicalprecipi-tatesform;(a)PleasedescribethestepstakentoensurethatthesurfaceconditionofthesusedintheCHLEtestsisrepresentativeofthe remainingaluminumintheplant.RemovedResponse,Pg.158(b)Pleaseexplainifthecorrosionbehaviorofthedtpartsofthe(i.e.,thepartusedforsubmergedsamplesandthepart usedforvaporsamples)wasevercomparedbyplacingtheminthe exactsametestconditions,suchasinabenchtest.RemovedResponse,Pg.159(c)PleaseexplainifthessurfaceconditionwasevaluatedtodetermineifaLOCAjetorthethermaltransientfromaLOCAwould causetheoxidetospall,potentiallyresultinginagreatercorrosion ratethanwasobservedduringtheCHLEtesting.RemovedResponse,Pg.15914.PleasediscusshowuncertaintiesfromthefollowingitemsareconsideredintheSTPchemicalanalysis:Tuesday1 stMarch,2016:19:32,Page56of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(a)Radiationonprecipitateformation.

RequiredResponse,Pg.268(b)Radiationondebrisbeddegradation.Inaddition,forthisitem,thesubmittalstates(Volume6.2,page84)thatbreakdownofthe "berbedisnotconsideredtobeasigni"cantissueduetosimilar materialsbeingusedfor"ltrationmediaforhighactivityparticulate.

Pleasediscusshowthe"lterservicelifeinthereferencedapplication comparestotheECCSmissiontimefollowingaLOCA.

RequiredResponse,Pg.268(c)Eofunquali"edcoatingsdegradation.Forexample,pleaseex-plainifleachedchemicalsfromthecoatingsatSTPcontributeto potentialchemicalPleaseexplainifthecoatingsthemselves becomeadebrissourcethatismoreproblematicthanparticulates (e.g.,gelatinous).Aspartoftheresponse,pleasecomparethecoatings testedinthereportreferencedintheLARtotheSTPplant-speci"c unquali"edcoatings.

RequiredResponse,Pg.27015.TheCHLEtestssimulateda15-inchLBLOCA.PleasedescribehowtheCASAGrandechemicalmodeldeterminesthechemicalsourcetermfor tsizebreaks,suchasasmallerthan15-inchLBLOCAoralarger than15-inchLBLOCA.Inaddition,pleaseexplainifCASAGrandecon-sidershowasmallerbutpotentiallymorefocusedjetthattakeslongerto blowdownmaythecalciumandaluminumconcentrations.RemovedResponse,Pg.27016.Volume1,Section1.2.6,"ChemicalReleaseandPrecipitationModel,"statesthatseveralscenarioswereinvestigatedusingtheWCAP-16530-NP-Aformulaforchemicalrelease.Thescenariosusedtcombinations ofliquidtemperature,pH,watervolume,and"berquantityforseveral tbreaksizesuptoadoubleendedguillotinebreak.Pleaseclarify ifTables2.5.34and2.5.35inVolume6.2summarizetheresultsofthese investigations.Pleaseprovidetheminimumandmaximumvaluesforthe pH,"berquantity,andwatervolumeinthetables.Alsopleasediscussif post-LOCAvaluescouldreasonablyexceedtheminimumandmaximum valuesusedintheevaluations.Forexample,pleaseexplainifitisplausible forthepHtobegreaterthanwasassumedtobethemaximumpH.RemovedResponse,Pg.27117.Page187ofVolume3statesthechemicalbump-upfactorshouldneverbelessthanone,andthereisapracticalmaximumabovewhich alleventswillleadtosumpfailure.Pleasediscussinmoredetailthe approximatevalueofabumpupfactorthatwillleadtosumpfailure.

Pleaseprovidethevaluesforconventionalheadlossthatareassumed.RemovedResponse,Pg.18718.Volume6.2,"Item5.a.6:CorrosionandDissolutionModel,"onpage72statesthefollowing:Thedeterminationofwhetherachemicalproductwouldformwasbasedonacombinationofengineeringjudgmentandlimited thermodynamicmodeling.Thetotalquantityofmaterialreleased wasnotassumedtofullyprecipitateintochemicalproducts.In-stead,solubilitylimitsofchemicalproductsexpectedtoform...Tuesday1 stMarch,2016:19:32,Page57of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONwerecalculatedasafunctionoftemperatureandpHusingVi-sualMINTEQtodeterminethelowestconcentrationofmetal requiredforproductformationfromtherangeofselectedcon-ditions.Sodiumaluminumsilicateandaluminumoxyhydroxide arethealuminumproductsdescribedaspossibleprecipitatesin WCAP-16530-NP-A;howeveronlythealuminumhydroxidesol-ubilitylimit(LogKof10.8...)wasconsideredinthisanalysis sinceitwasdeterminedasasuitablesubstituteforsodiumalu-minumsilicateinheadlosstesting....Calciumphosphate(Log Kof-28.25)solubilitylimitswerealsoevaluated.Thelowestconcentrationofmetalsrequiredproductsweredeter-minedbyidentifyingtherangeof7.0to7.3atade"nedtemper-ature.Usingthisapproach,theconcentrationofaluminumexpectedtoresultinformationofachemicalproductisapproximately4.9milligramperliter (mg/L).Thecalciumconcentrationexpectedtoresultintheformation ofachemicalproductwas0.8mg/L.Thesevalueswereusedtoassess thepresenceofchemicalproductformationfromthecalculatedmaterial

release.(a)PleasedescribewhytheNRCsjudgmentthataluminumoxy-hydroxideandsodiumaluminumsilicateprecipitatespreparedusing theWCAP-16530-NP-Amethodcanbesubstitutedforeachotherin headlosstestingisrelevanttosolubilitywhenevaluatingwhetheran aluminumbasedprecipitatewillforminapost-LOCA"uidcontain-ingdissolvedaluminum.

RequiredResponse,Pg.272(b)UsingEquation4intheArgonneNationalLaboratoryTechnicalLetterReportAluminumSolubilityinBoronContainingSolutions asafunctionofpHandTemperature,datedSeptember19,2008 (ADAMSAccessionNo.ML0918b10696),thelowestaluminumsolu-bilityinthepHrange7.0to7.3isapproximately2.7partspermillion (ppm).Pleasediscusshowtheanalysisresultswouldbeby assumingthealuminumsolubilitywas2.7mg/Linsteadof4.9mg/L.RemovedResponse,Pg.272(c)Thediscussionstatesthatcalciumphosphatesolubilitylimitswereevaluated.Figure2.5.34(Volume6.2)showsthecalciumhydroxide solubilityinborated-TSP[trisodiumphosphate]solution.Pleasedis-cusstherationaleforthe0.8mg/Lsolubilityforcalciumandwhether itwasbasedonacalciumhydroxidesolubilityorcalciumphosphate solubility.RemovedResponse,Pg.27219.ThecaptionforFigure5.6.6(Volume3)statesTypicalsampleofsump-strainerheadlosshistoriesgeneratedundertheassumptionofexponential chemicalfactorandarti"cialhead-lossin"ation.Pleaseclarifyifthe arti"cialheadlossin"ationreferstotheNUREG/CR-6224,Parametric StudyofthePotentialforBWRECCSStrainerBlockageDuetoLOCA GeneratedDebris,October1995(ADAMSAccessionNo.ML083290498),

correlationmultipliedby5orsomeothervalue.RemovedResponse,Pg.161Tuesday1 stMarch,2016:19:32,Page58of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION20.Pleasediscusswhatbenchmarkingwasperformedwitha)STPspeci"cstrainertestsandb)industrytestdatawithsimilarconditionsforthe baselineheadlossandchemicalbumpupfactor.RemovedResponse,Pg.18821.TheamountofcrudreleasedfollowingaLOCAisestimatedtobe5-24pound-mass(Ibm)(Volume6.2,page85).FortheCASAGrandeanalysis, pleasediscussthequantityofcrudorotheractivateddebristhatisassumed toreachthestrainerandhowitheadloss.Pleasecomparethe totalcrudquantityestimatedwiththeamountofcrudcollectedduringa controlledcrudburstperformedatthebeginningofrefuelingoutages.

RequiredResponse,Pg.27322.Atotalof"veCHLEtanktestswereperformedtoevaluateSTPplant-speci"cchemicaltests.CHLETests1and2wereintendedtoeval-uateanMBLOCAandanLBLOCA,respectively.Pleaseaddressthefol-lowingquestionsrelatedtoTests1and2:(a)PleasediscusswhythetestscreendebrisbedisanacceptablemethodfordetectionofchemicalprecipitatesgiventheearliertestCHLE-010,CHLETankTestResultsforBlendedandNEI[NuclearEnergy Institute]FiberBedswithAluminumAddition,thatshowednohead lossresponseeveninthepresenceoflargequantitiesofaluminum oxyhydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.Note:AdditionaldetailsareavailableinaSeptember 6,2012,meetingsummarydatedOctober4,2012(ADAMSAccession No.ML12270A055).

RequiredResponse,Pg.189(b)Pleasedescribewhytheuseofonlyaluminumand"berglassintheMBLOCAtestadequatelyrepresentstheplantspeci"cenvironment.

RequiredResponse,Pg.1911.3.5.2Coatings1.Pleaseprovidethebasisfortheunquali"edepoxysizedistributionreportedinTable2.2.18inVolume3.TheNRChaspreviouslyallowedlicensees toassumethatdegradedquali"edepoxycoatingsfailinpieceslargerthan "nes.Thisallowancewaslimitedtoepoxycoatingsthatwereoriginally quali"edandhavebecomedegraded.Thesametreatmenthasnotbeen acceptedforepoxycoatingsthatwereunquali"ed,sincethesearetypi-callylessrobustcoatingsystemsthatwoulddisintegrateinto"nes.Please specifytheepoxycoatinginquestionandprovideabasis(i.e.,testing)for assumingitfailsinpieceslargerthan"nes.RemovedResponse,Pg.2732.Table2.2.16inVolume3providesthequantityofquali"edcoatingsgen-eratedwithintheZoneofIn"uence(ZOI)forvariouspipediameters.The ZOIusedtocalculatethesequantitiesisnotprovided.Pleaseprovidethe ZOIusedforbothepoxyandinorganiczinc(IOZ)quali"edcoatings(e.g.,

epoxy=4D,IOZ=10D).

RequiredResponse,Pg.2743.Section5.4.5,Unquali"edCoatingDebris,inVolume3statesthatthetotalfailurefractionisassumedtobe100%forallunquali"edcoatings.

Giventhisstatement,pleasedescribethesigni"canceofthefailurefraction analysisprovidedonpages11through17inVolume6.2.PleaseclarifyifTuesday1 stMarch,2016:19:32,Page59of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthefailurefractionanalysisisusedinanymannerintheCASAmodeloriftheunquali"edcoatingsarealwaysassumedtohavea100percentfailure

fraction.RemovedResponse,Pg.2744.Forunquali"edcoatingsthatarenotlocatedintheuppercontainment,theNRCsunderstandingisthat100percentofthecoatingsareas-sumedtofailandareavailablefortransporttothestrainer.Thealso understandsthat100percentofthecoatingsthatarecalculatedtotrans-porttothestrainerareassumedtoarriveatthestraineruniformlyover the"rst36hours.Pleasecon"rmthatthesunderstandingiscorrect.

Also,pleaseprovidedetailsrelatedtotheunquali"edcoatingfailureas-sumptionsintermsofpercentages,timingandquantitiesthatarriveat thesumpstrainer.RemovedResponse,Pg.2745.Equations27and28(page157,Volume3)refertoF(t)asthefractionofcoatingsthatfailduringaspeci"ctimeperiod.Pleaseprovidethevalue ofF(t)anddescribetheanalysisperformedtoarriveatthatvalueforthe timeframeduringwhichuppercontainmentsprayisactiveandcapableof transportingcoatings(theinitial24hours).PleasestateifF(t)isthesame forallunquali"edcoatingtypes.Inaddition,pleaseprovidethecumulative massofunquali"edcoatingsthatfailintheuppercontainmentinthe"rst 24hoursinthecurrentanalysis.RemovedResponse,Pg.2776.TheVolume6.2responsestorequestforsupplementalinformation,indi-catethatthefailuretiminganalysisreliesheavilyon"lterdatafromthe EPRIDBAtestingoforiginalequipmentmanufacturer(OEM)coatings.

PleaseaddressthefollowingquestionsregardingSTPsuseofthistest

data:(a)PleasedescribewhatSTPhasdoneintermsofdocumentationreviewortestingofplantmaterialsinordertoensurethattheplant-speci"c unquali"edcoatingsatSTParethesameasthecoatingsusedinthe EPRItesting.

RequiredResponse,Pg.280(b)The"nalproprietaryEPRIreportonOEMCoatings(EPRI1011753,DesignBasisAccidentTestingofPressurizedWaterReactorUn-quali"edOriginalEquipmentManufacturerCoatings.FinalReport,September2005),statesthat,Duetotheprohibitivenatureofthe task,therewasnoattempttoquantifytheamountofdebriscaptured inthe"lters.Thistestingincludedmanydtcoatingtypeswith varyingcolor,density,andconstituentparticlesize.Theautoclave wasnotopenedandthetestedcomponentswerenotexamineduntil theentiretestwascomplete.TheNRCcouldnotdetermineif lightercoatingswhichwouldbelessvisibleona"lter(andcertainly lessvisibleonaphotoofa"lter)failedatthesamerateasdarker coatingsoriftheymayhavebeenpresentononeormoreofthe"lters removedearlyinthetest.Giventhisinformationandthefactthat thetestersstatedthattheymadenoattempttoquantifydebrison the"lters,pleaseprovideadditionaljusti"cationforusingthistest datatoassignafailuretimetounquali"edcoatings.RemovedResponse,Pg.280Tuesday1 stMarch,2016:19:32,Page60of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(c)TheEPRIOEMreportalsostatesthat,Withregardtotimingofthecoatingfailures,the"ltersdonotdemonstrateade"nitivetime offailure,howeverinsubjectiveterms,itappearsthatmuchofthe failureoccurredinthe24-to48-hourtimeframe.STPseekstoreduce thetransportedunquali"edcoatingdebrisfromuppercontainmentby 94percentcomparedtoadeterministicapproach(100percentfailure inadeterministicevaluation,6percentforSTP).TheNRCis notpersuadedthatasubjectivereviewofphotographsfromatest performedin2005isadequatejusti"cationfortheproposedfailure timing.Pleaseprovideadditionaljusti"cationforthecurrentanalysis orprovidearevisedvalueforthefailuretiming.RemovedResponse,Pg.2807.Pleasedescribeanyongoingcontainmentcoatingconditionassessmentprogram.Pleaseincludethefrequencyandscopeoftheinspections,accep-tancecriteria,andthequali"cationofpersonnelwhoperformcontainment coatingsconditionassessmentinspections.

RequiredResponse,Pg.2811.3.6SCVB:ContainmentandVentilationBranch1.InsupportofEnclosure2-3,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion[GDC]38,pleaseprovidethe following:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-38.

RequiredResponse,Pg.192(b)Pleasedescribethespeci"crequirementsofGDC-38thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.1922.InsupportofEnclosure2-4,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion41,pleaseprovidethefollowing:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-41.

RequiredResponse,Pg.192(b)Pleasedescribethespeci"crequirementsofGDC-41thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.1923.Enclosure3,page4,paragraphUseofaRisk-InformedApproachtoRe-solvingGSI-191,states:Thedesignandlicensingbasisdescriptionsofaccidentsrequir-ingECCSoperation,Includinganalysismethods,assumptions, andresultsprovidedinUFSAR[UpdatedFinalSafetyAnalysis Report]Chapters6and15remainunchanged.Thisisbasedon thefunctionalityoftheECCSandCSSduringdesignbasisacci-dentsbeingcon"rmedbydemonstratingthatthecalculatedrisk associatedwithGSI-191forSTPUnits1and2isVerySmall andlessthantheRegionIllacceptanceguidelinesde"nedbyRG

1.174.Tuesday1 stMarch,2016:19:32,Page61of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONThecurrentlicensingbasiscontainmentanalysismethodologyusedtocon-"rmtheadequacyofthecontainmentheatremovalsystem(whichcomplies with10CFR50AppendixAGDC-38)describedintheUFSARist fromtheproposedmethodologywhichresolvesGSI-191onarisk-informed basisandproposesanexemptionrequestfromGDC-38.Forexample:(a) inthesinglefailureassumptionintheproposedandcurrent analysis;(b)computercodesRELAPforLOCAmassandenergy(M&E) release,andMELCORfortheLOCAsumptemperatureresponseareused intheproposedanalysis,andSATAN-VI,WREFLOOD,FROTHareused forM&EreleaseandCONTEMPT4/MODSisusedforsumptemperature responseinthecurrentanalysis;and(c)theproposedanalysisinputsand assumptionsarerequiredtobeconservativefromGSI-191perspectiveand alsorequiredtobeconservativeforsumptemperatureresponsewhereas thecurrentanalysisinputsandassumptionsareconservativeforsump temperatureresponse,(a)PleasejustifywhytheUFSARlicensingbasisdescriptionofthemethod-ologyusedforcon"rmingtheadequacyofcontainmentheatremoval systemwhichcomplieswithGDC-38shouldnotbereplacedwiththe proposedlicensingbasismethodologywhichtakesanexemptionfrom GDC-38.complieswithGDC-38shouldnotbereplacedwiththepro-posedlicensingbasismethodologywhichtakesanexemptionfrom

GDC-38.RequiredResponse,Pg.193(b)Tabulatethedbetweentheinputsandassumptionsbetweenthecurrentlicensingbasiscontainmentanalysisthatcalculatesthe mostlimitingsump"uidtemperaturepro"leforavailableNPSHcal-culationandtheproposedcontainmentanalysisperformedforrisk-informedGSI-191.Pleasejustifythattheinputsandassumptionsin theproposedmethodologyareconservativefrombothGSI-191and sumptemperatureresponseperspectives.

RequiredResponse,Pg.193(c)IncasetheUFSARlicensingbasisdescriptionofthecontainmentheatremovalsystem,includingitsrelatedmassandenergyrelease analysismethodology,isrequiredtobereplaced,pleaseprovidethe revisedUFSARinputforNRCreviewandapproval.

RequiredResponse,Pg.1964.Thecurrentlicensingbasismethodologyfortheiodineremovalisdoc-umentedinUFSARSection6.5.2,ContainmentSpraySystem-Iodine Removal.TheiodineremovalisaccomplishedbytheCSSwhichmeets therequirementsof10CFR50AppendixAGDC-41.Theproposedrisk-informedGSI-191methodologytakesexemptionfromcompliancewith GDC-41requirements.(a)PleasejustifywhytheUFSARlicensingbasisdescriptionoftheiodineremovalshouldnotberevisedwiththeproposedmethodologywhich takesexemptionfromGDC-41.

RequiredResponse,Pg.196(b)PleasetabulatethedbetweentheinputsandassumptionsbetweenthecurrentlicensingbasiscontainmentatmospherecleanupTuesday1 stMarch,2016:19:32,Page62of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONmethodandtheproposedcontainmentatmospherecleanupwhichtakesexemptionfromtheGDC-41requirements.

RequiredResponse,Pg.197(c)IncasetheUFSARlicensingbasisdescriptionoftheiodineremovalsystemisrequiredtobereplaced,pleaseprovidetherevisedUFSAR inputforNRCreviewandapproval.

RequiredResponse,Pg.1975.InsupportofVolume6.2,pleaselistthedbetweentheheatsinksinthecurrentlicensingbasiscontainmentanalysisdocumentedintheUF-SARTables6.2.1.1-7and6.2.1.1-8andintheproposedcontainmentanal-ysisforrisk-informedGSI-191.Pleaseprovidejusti"cationincaseswhere theconservatismisreducedintheproposedanalysis.

RequiredResponse,Pg.1976.InsupportofVolume6.2,pleaselistthedbetweentheLOCAsurfaceheattransfermodelforheatsinksinthecurrentlicensingbasis analysisdocumentedinUFSARTable6.2.1.1-9andthemodelinthepro-posedcontainmentanalysisforrisk-informedGSI-191.Providejusti"ca-tionfortheincasetheconservatismisreducedintheproposed

analysis.RequiredResponse,Pg.1977.NUREG-0800,StandardReviewPlanfortheReviewofSafetyAnalysisReportsforNuclearPowerPlants:LWREdition(SRP),Section6.2.1.5, MinimumContainmentPressureAnalysisforEmergencyCoreCooling SystemPerformanceCapabilityStudies,describestheminimumcontain-mentpressureanalysisforECCSperformancecapability.RG1.157,Best EstimateCalculationforEmergencyCoreCoolingSystemPerformance, May1989(ADAMSAccessionNo.ML003739584),Section3.12.1,Con-tainmentPressure,providesguidanceforcalculatingthecontainment pressureresponseusedforevaluatingcoolingeenessduringthepost-blow-downphaseofaLOCA.UFSARSection6.2.1.5documentsthecurrentminimumcontainmentpres-sureanalysisforperformancecapabilitystudiesoftheECCS.Pleasede-scribetheproposedcontainmentanalysis,includingassumptionsandin-puts,performedforthecalculationofminimumcontainmentpressurein-putfortheECCSanalysisthatcalculatesthepeakcladdingtemperature forrisk-informedGSI-191.Pleasejustifythattheinputsandassumptions areconservativeforthepurpose.

RequiredResponse,Pg.1978.Volume6.2,page117,Item5.a.14,In-VesselThermalHydraulicAnal-ysis,listssixscenariossimulatedusingthe3DVessel-1DCoreModel.

PleasedescribeandjustifythebasisforselectionoftheseLOCAbreaks

scenarios.

RequiredResponse,Pg.1989.InsupportofEnclosure2-2,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion35,pleaseprovidethefollowing:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-35.

RequiredResponse,Pg.198(b)Pleasedescribethespeci"crequirementsofGDC-35thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.199Tuesday1 stMarch,2016:19:32,Page63of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.3.7SNPB:NuclearPerformanceandCodeReviewBranch1.PleaseprovidethefollowinginformationfortheSTPNuclearSteamSup-plySystems(NSSSs):(a)Volumeofthelowerplenum,coreandupperplenumbelowthebottomelevationofthehotleg,eachidenti"edseparately.Also,pleaseprovide theheightsoftheseregionsandthehot-legdiameter.

RequiredResponse,Pg.199(b)Loopfrictionandgeometrypressurelossesfromthecoreexitthroughthesteamgeneratorstotheinletnozzleofthereactorvesselforsteady statefullpoweroperation.Also,providethelockedrotorreactor coolantpump(RCP)k-factor.Pleaseprovidethemass"owrates, "owareas,k-factors,andcoolanttemperaturesforthepressurelosses provided(upperplenum,hotlegs,SteamGenerators(SGs),suction legs,RCPs,anddischargelegs).PleaseincludethereducedSG"ow areasduetopluggedtubes.Also,providethelossfromeachofthe intactcoldlegsthroughtheannulustoasinglebrokencoldlegand theequivalentloopresistanceforthebrokenloopandseparatelyfor theintactloop.Pleaseidentifythe"owarea(hydraulicdiameter)on whichthek-factorsarebased.

RequiredResponse,Pg.201(c)CapacityandboronconcentrationoftheRWST.

RequiredResponse,Pg.203(d)Capacityofthecondensatestoragetank(CST).

RequiredResponse,Pg.203(e)Flushing"owrateatthetimeofswitchtosimultaneousinjection.

RequiredResponse,Pg.203(f)Highpressuresafetyinjection(HPSI)runout"owrate.

RequiredResponse,Pg.205(g)Capacitiesandboronconcentrationsforhighconcentrateboricstor-ageacidtanks,ifpartofsystem.

RequiredResponse,Pg.205(h)FlowrateintotheRCSfromtheboricacidstoragetanks,ifapplica-ble.RequiredResponse,Pg.205(i)TimetoemptytheRWST(allpumpsoperating).

RequiredResponse,Pg.205(j)Minimumcontainmentpressureorcontainmentpressureversustimegraph.Response,Pg.205(k)Sumpboricacidconcentrationversustime.

RequiredResponse,Pg.207(l)MinimumRWSTtemperature.Response,Pg.207(m)Injectiontemperatureversustimefromsumpduringrecirculation.

RequiredResponse,Pg.2072.Pleaseprovidethefollowingelevationdata:(a)bottomelevationofthesuctionleghorizontallegpipingandcoldleg diameter RequiredResponse,Pg.208(b)topelevationofthecoldlegattheRCPdischargeResponse,Pg.208(c)topelevationofthecore(alsoheightofcore)

RequiredResponse,Pg.208(d)bottomelevationofthedowncomer RequiredResponse,Pg.2083.Pleaseprovidethelimitingbottomandtopskewedaxialpowershapes RequiredResponse,Pg.209Tuesday1 stMarch,2016:19:32,Page64of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION4.Pleaseprovidethelatestanalysisorreferenceshowingthetimingforboricacidprecipitationforthelimitinglarge-breakandsmall-breakLOCAs.

RequiredResponse,Pg.2835.Justi"cationanddescriptionofthemethodologyusedtocomputethesumpboricacidconcentrationversustime.

RequiredResponse,Pg.2101.3.8SRXB:ReactorSystemsBranchTheNRCrequeststhelicenseetoprovidethefollowing:1.RELAP-3Dinputdecksforthesecaseswitha3-Dvesseland1-Dcore:(a)SteadystatecaseinColdLeg(b)MediumBreakLOCA(6)inColdLeg(c)Double-EndedGuillotine(DEG)BreakinColdLeg(d)Coreblockageinput"le RequiredResponse,Pg.1612.RELAP-3Dinputdecksforthesecaseswitha3-Dvesseland3-Dcore:(a)SteadystatecaseinColdLeg(b)MediumBreakLOCA(6)inColdLeg(c)DEGBreakinColdLeg(d)DEGBreakinColdLegwithmaximumboron(e)Coreblockageinput"le RequiredResponse,Pg.1613.ConversiontablesbetweenRETRANandRELAP-3D(SouthTexasProjectPowerPlantRETRAN-RELAP-3DConversionTables?

RequiredResponse,Pg.1614.Documentationdescribingmodelveri"cation(SouthTexasProjectPowerPlantRELAP-3DSteady-statemodelVeri"cation)

RequiredResponse,Pg.1615.Table2.2.1inVolume3providesresultsforsumpswitchovertimebasedonthebreaksizeduringalossofcoolantaccident(LOCA).Theapplication statesthatthetimingforswitchovertorecirculationisdependentonthe volumeofwaterintheRWSTandthetotalECCSandCSS"owrate.(a)PleaseprovidetheassumptionsusedforthevolumeofwaterintheRWSTfortheresultsinTable2.2.1.Pleaseprovidejusti"cationfor useoftheseassumptions.RemovedResponse,Pg.161(b)PleaseprovidetheECCS"owrateandCSS"owrateforeachbreaksizeinTable2.2.1.Required(strnr.pen.)Response,Pg.162(c)Pleaseexplainhowsumpswitchovertimeiscalculatedbasedontheresponsestoa.andb.above.RemovedResponse,Pg.1626.Section2.2.1inVolume3describestheterminationcriteriaforcontain-mentsprays.Oneofthecriteriatoterminatecontainmentspraysisthat containmentpressurehasdroppedbelow6.5psig.Pleaseprovideplotsfor containmentpressureversustimeforarangeofbreaksizestoverifypres-suredropsbelowtheterminationcriteriaof6.5poundspersquareinch gauge(psig)before6.5hours.Removed(NoRCBovepressure)Response,Pg.163Tuesday1 stMarch,2016:19:32,Page65of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION7.Switchovertohot-leginjectionisstarted5.5hoursafterthebeginningoftheLOCAeventandisassumedtobecompletedbetween5.75and6hours.(a)PleasesummarizetheEmergencyOperatorProcedures(EOPs)thatdirecttheoperatorstotakethisactionandanassociatedtimelineof theoperatorkeyactionsifthiseventweretooccur.

RequiredResponse,Pg.163(b)Pleaseprovideajusti"cationthatdemonstratesthe15-30minuteresponsetimeisachievableduringswitchovertohotleginjection trainingscenarios.Inthejusti"cation,pleaseincludetheresultsof simulatorrunsandtraininglogs.

RequiredResponse,Pg.1638.Table2.2.14(Volume3)showssafetyinjection(SI)"owratesfornominaloperatingconditions.Pleasejustifytheuseofnominalconditionsversus theuseoflimitingconditionswhenanalyzingLOCA.

Required(strainerpen-

etration)Response,Pg.1649.Pleasedescribethetermstotalsump"ow,totalSl"ow,andECCS"ow.Pleaseincludeifhighheadsafetyinjection(HHSI),lowheadsafetyinjec-tion(LHSI),orCSSisapartofeachde"nition.Required(strnr.pen.)Response,Pg.1641.3.9SSIB:SafetyIssueResolutionBranch

• ZOI1.Volume3,Table5.3.1listsDoubleEndedGuillotineBreak(DEGB)equivalentdiametersandTable5.3.2listscomputeraideddesign (CAD)DEGBvalues.Thesevaluesarecalculatedbydoublingthe singlesidedbreakareaandthencalculatinganequivalentpipediam-eter.ApprovedZOIsarebasedondoublingthevolumeofsinglesided breakjets(calculatedbytheAmericanNationalStandardsInstitute (ANSI)model)andcalculatingaradiusforaspherebasedonthat volume.PleasedescribehowtheCADDEGBvaluescalculatedby Equation22ofVolume3areused.

RequiredResponse,Pg.166

• DebrisCharacteristics2.PleaseprovidethesizedistributionsforNukonandThermalWrapdebriscreatedbythepostulatedLOCAjet(percentageofeachsize categorycreated).Pleaseprovidethemethodologyused,including thebases,todeterminethesizedistributions.Pleaseprovideinfor-mationregardingwhetherthedistributionisasimplepercentageof allgenerated"brousdebrisorbasedonthedistanceoftheinsulation fromthebreak(Volume3,Sections2.2.15,InsulationDebrisSize Distribution,4.2,StructuresInformationProcessFlow,and5.4.2, InsulationDebrisSizeDistributionModel).

RequiredResponse,Pg.1663.PleaseclarifyifthematerialpropertiesofdebrislistedinTable2.2.21ofVolume3areusedintheheadlosscorrelation.Ifso,pleasestateif varyingthesizesoftheparticlestoamorerealisticdistribution theresultssigni"cantly.Explainhowtheparticulatedebristypesthat havesizedistributionsareimplementedinthecorrelation.Pleaseex-plainwhethertheuncertaintyofthesizedistributionofthematerialsTuesday1 stMarch,2016:19:32,Page66of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcanthepermeabilityofthedebrisbedandthereforetheheadloss.Isthisuncertaintysigni"cant,andifso,pleasestatehowisit accountedforintheSTPmodel.RemovedResponse,Pg.285

• Transport4.Pleaseprovidejusti"cationforassumption6.h.i.ofVolume3(page78).AccordingtoTable2.2.22ofVolume3,linebreaksbelowSGand surgelineresultinagreaterpercentageofsmalldebrisbeingblown directlytolowercontainment.Thisdebrisisconsideredtoenterthe pooldirectlywhiledebrisblowntouppercontainmentmaybeheldup.PleaseexplainwhytheSGcompartmenttransportfractionsare consideredtobeconservativecomparedtotheseotherbreakloca-

tions.RequiredResponse,Pg.2855.Pleaseexplainassumption6.h.vofVolume3(page79).Pleasede-scribehowthenumberofstrainersinservicepool"lltrans-port.Itappearsthatthepool"lltransportphasewouldbelargely completedpriortostrainersbeingplacedinservice.Response,Pg.1666.Fortheblowdowntransportevaluation,itwasnotclearhowtheDrywellDebrisTransportStudy(DDTS),NUREG/CR-6369,Dry-wellDebrisTransportStudy,Volumes1,2,and3,September1999(ADAMSAccessionNos.ML003728226,ML003726871,andML003728322,respectively),resultswereappliedtotheplantcondition.

(

Reference:

Volume3,Section2.2.17,SlowdownTransportFrac-tions,andVolume6.2,Item5.a.2(page37).Pleaseprovidethefol-lowinginformation:(a)TheDDTScautionsthatifgratingsdonotcovertheentiretrans-portpath,theymaynotbeaseeindebriscapture.For transportpathswheregratingdoesnotfullyspanthetransport pathway,pleasestateifthecapturemetricswasadjustedtoac-countforthispotential.

RequiredResponse,Pg.288(b)Pleasestateifthecalculationalmethodologyaccountfordeple-tionofdebris,asitiscapturedonupstreamobjects.Pleaseclarify iftheamountreachingthesecondandthird(etc.)objectsre"ects thedebrislostonupstreamobjects.Thiswasnotapparenttothe NRCuponinspectionoftheequationsusedtoperformthe

calculation.

RequiredResponse,Pg.288(c)Pleaseexplainwhatwasconsideredtobea90degreeturnintheplantandhowthiscomparedtothe90degreeturnsmodeledin theDDTS.PleaseexplainhowitwasdeterminedthattheDDTS resultsareapplicabletotheSTPconditionsconsideredtobe90 degreeturns.

RequiredResponse,Pg.290(d)Pleaseclarifyiftherearelimitstothemassofdebristhatcanbecapturedonstructuresoronspeci"csurfaceareasofstructures and,ifapplicable,howsuchlimitswouldthecalculations forholdup.Response,Pg.293(e)PleaseexplainhowtherangesofvaluesusedintheDDTSweredeterminedtobeapplicabletotheSTPconditions.

RequiredResponse,Pg.297Tuesday1 stMarch,2016:19:32,Page67of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION7.ForthewashdowntransportevaluationitwasnotcleartotheNRCthattheDDTStestresultswereappliedrealisticallyorconser-vativelytotheSTPplantconditionasdescribedinVolume1,Section 1.2.3,WashdownTransport,Volume3,Section2.2.18,Washdown TransportFractions,andItems5.a.3and5.a.5ofVolume6.2.Please providethefollowinginformation:(a)Pleasestateifthewashdownevaluationconsideredthatitmaybemorelikelyforapieceofdebristhathasbeenblownthroughone ormoregratingstosubsequentlywashdownthroughgratings.It appearsthattheDDTSdidnotusedebristhathadbeenpassed throughgratingswhenstudyingwashdownthroughgratings.

RequiredResponse,Pg.301(b)TheDDTSwashdowntestswererunfor30minutes.TheDDTSstatedthatmostwashdownoccurredinthe"rst15minutes.It wasnotcleartotheNRCsfromthetestresultshowwash-downoverasigni"cantlylongerperiodoftimewouldoccur.

PleaseexplainwhytheDDTSresultsareapplicabletosigni"-

cantlylongerwashdownperiods.

RequiredResponse,Pg.302(c)Pleasestateifdebrisiswasheddownthroughonelevelofgrating,ifitismorelikelytowashthroughsubsequentlevels.Ifitwashes throughmorethanonegrating,isitmorelikelytopassthrough subsequentlevels?Pleaseexplainhowthetransportevaluation accountsforsuchalikelypotential.Whatwasconsideredwhen determiningtheretentionfractionsfordebrisonadditionallevels ofgratinginthewashdowntransportevaluation?Itwasstated thatengineeringjudgmentwasusedinthisdetermination,but theNRCdidnot"ndanadequatebasisdocumentedforthe engineeringjudgment.

RequiredResponse,Pg.303(d)Pleasestateifthewashdowntransportevaluationaccountedforthesigni"cantlyhighervelocitiesthatmayoccurwithsheeting "owatthebeginningofwashdown.

RequiredResponse,Pg.303(e)Thesubmittalprovidedthecalculationsforwashdownpercent-ages.Item5.a.3(Volume6.2,page43)usesvaluesof0.4and 0.5forF wgfractionofdebrisheldupwhenwashedthroughthe"rstlevelofgrating.TheDDTSstatesthat40-50percentpassthrough.Pleaseclarifyif0.4and0.5bereversedorifthe0.4 shouldbechangedto0.6.Theterminologyusedisnotclearand canbemisunderstood.

RequiredResponse,Pg.304(f)Table2.5.24ofVolume6.2istitled,Washdowntransportfrac-tionsusedinCASAGrande,buttheleadingparagraphstates thatthetablecontainsblowdownfractions.Pleaseclarifywhether itisblowdowntransportfractionorwashdownblowdowntrans-port.RequiredResponse,Pg.3048.Theevaluationfortransportofpartiallysubmergeddebrisontheop-eratingdeckmakesseveralunsubstantiatedassumptions(Item5.a.5, Volume6.2,page54).Pleaseprovidethefollowinginformation:(a)PleaseexplainiftheassumedsizedistributionconsideredthatmostofthedebrisblowntotheoperatingdeckwouldpassthroughTuesday1 stMarch,2016:19:32,Page68of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONgratingthuslikelyreducingthesize.Pleaseclarifyiftheassumedsizedistributionwasadjustedforthis RequiredResponse,Pg.304(b)Pleasestateiftheevaluationconsideredthattheinitialsheeting"owmaybeatahighervelocitythanthesteadystate"owandthatthismaypushdebrisacrossthe"oorbeforeasteadystate occurs.RequiredResponse,Pg.305(c)Pleasestatethebasisfortheporosityequation.Pleaseexplainwhythebulkdensity(as-fabricated)ofthe"berisrelevantafterit hasbeenrenderedintosmallpiecesandthenbeenblownthrough

grating.RemovedResponse,Pg.305(d)Pleaseclarifyiftheevaluationconsideredthatairmaybetrappedwithinthe"berandthatitmaypickupadditionalairasit tumblesacrossthe"oor.RemovedResponse,Pg.305(e)Pleasestateifthereisanyexperimentaldataavailabletovalidatethecalculationalmethodology.

RequiredResponse,Pg.3059.ItwasnotcleartotheNRCifthe"brousdebriserodedfromlargeandsmallpiecesofdebriswereaddedtothe"netransportterm.

Pleaseclarifythattheerodedtermwasaddedtothe"nesourceterm andisnotaddedasthesizecategoryfromwhichtheywereeroded.For example,inFigure5.5.3ofVolume3,thetransporteddebrisshould be1.8percent"nesand35.6percentsmallwhilethetotalshows 37.4percenttransported(35.6+1.8).Pleasestateiftheevaluation includesthe1.8percentas"nedebris.

RequiredResponse,Pg.16710.Thesubmittalstatesthatunquali"edcoatingsthatfailafterthespraysaresecuredcannottransporttothecontainmentsump(Refer-enceVolume1,Section1.2.3,WashdownTransport,Volume3,Sec-tion2.2.10,Unquali"edCoatingsQuantity,Volume3,Section5.4.5, Unquali"edCoatingsDebris,Volume3,Section5.5.7,Strainer Transport).Pleaseexplainhowitwasdeterminedthattheywould nottransport.Pleaseclarifyiftherearetransportmechanismsbe-sideswashdownfromcontainmentspraythatcouldcausesomeof thecoatingstotransport.Forexample,pleaseexplainifcoatingsare locatedinareaswheretheycouldfalldirectlyintothesumporfall relativelyfreelytothesump.Explainifthe"owofcondensationon surfacescancarryparticlesoffailedcoatingstothesump,etc.(page 173,Section1.2.3;page571,Section2.2.10,page674,Section5.4.5, page680,Section5.5.7)

RequiredResponse,Pg.30511.Table5.5.5ofVolume3liststherecirculationdebristime,x(t)andstatesthatitisdescribedinSection5.8ofVolume3.TheNRC wasnotabletolocateadescriptionofthisvariable.Pleaseprovidea de"nitionofthedebrisrecirculationtime.Thefoundtheterm x(t)describedinSTPsinitialsubmittaldaredJune19,2013(page74 of174oftheattachment),whichhasbeensupersededinitsentirety.

Pleaseprovidearesponsetothefollowingquestions,whicharepar-tiallybasedontheinformationprovidedinJune19,2013,submittal.(a)PleaseprovideadescriptionoftherecirculationdebristimeasimplementedinsubmittaldatedNovember13,2013.RemovedResponse,Pg.167Tuesday1 stMarch,2016:19:32,Page69of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Pleasedescribethetypesandsizesofdebristowhichtherecir-culationdebristimeapplies.RemovedResponse,Pg.167(c)Pleasestateiftheequationassumeshomogeneousmixinginthepool.Ifso,pleaseexplainifthisthisisavalidassumptionforall debristypes.RemovedResponse,Pg.168(d)Itappearsthatthex(t)functioncalculatesthatalldebrisisatthestrainerattime=0anddecreasesastimeprogresses.Thisappears tobethereverseoftheactualconditionexpected.Pleaseexplain.RemovedResponse,Pg.168(e)Pleaseexplainthebasisforthedepletionrate.RemovedResponse,Pg.16812.BasedondescriptionofItem5.a.4ofVolume6.2(Page47),itisassumedthatdebriswillremaininthevicinityinwhichitwaswashed downuntilrecirculationstarts.Pleaseprovideadditionaljusti"cation forthisassumption.Pleasestateifthedebriswouldberedistributed duringpool"llincludingbypotentialsheeting"owandifthiswould theassumptionthatdebrisismixedhomogeneouslyinthepool atthestartofrecirculation.Ifso,pleasedescribewhichtypesand sizesofdebrisareRemovedResponse,Pg.21113.Table2.5.32ofVolume6.2includesvaluesforsmallpiecesofMi-crotherm.Thisisinconsistentwithotherstatementsinthesubmittal thatMicrothermisassumedtofailas100percent"nes.Pleaseclarify ifallMicrothermpiecesfailas"nes.Pleasestatehowsmallpiecesof MicrothermaretreatedinSTPsevaluation.RemovedResponse,Pg.169

• HeadLossandChemicalBumpUp14.TheSTPNOCsubmittalassumesthatnochemicalbumpupoccursifthedebrisbedthicknessislessthan1/16-inch(

Reference:

Volume 1,Section1.1,Step14;Volume3,Assumption7.c;Volume6.2,Items 5.a.10and5.a.11).TheNRChaspreviouslyconcludedthata 1/16-inchdebrisbedisanadequatemetricforthispurposeforclean plants,wheretheworstanalyzedbreakcouldresultin1/16-inchof "berwhenconservativemethodswereusedforestimatingtheamount ofdebrisgeneratedandtransportedtothestrainer.Thecleanplant criteriaalsoincludedotherrestrictionsfortheuseofthemetric,such asthelackofproblematicdebriswithinanyZOI.Thehasnot determinedthatthislimitisappropriateforamorerealisticrisk-informedevaluation.Thehasreviewedtestresultsconducted withabout1/16-inchof"brousdebristhatresultedinsomehead losswhenchemicalprecipitateswereaddedtothetest.Italsoappears thattheSTPevaluationhasnotconsideredallaspectsoftheclean plantcriteria.Whetherornotthecleanplantcriteriaarethebasis forthe1/16-inchlimit,pleaseprovideajusti"cationforitsuse.RemovedResponse,Pg.30615.TheSTPNOCsubmittalstatesthatthestrainerdebrisheadlossiscalculatedusingacorrelation(

References:

Volume3,Section5.6.2, ConventionalDebrisHeadLossModel,Volume3,Assumption7.e; Volume1,Section1.1,StructuredInformationProcessFlow.)The NRChasgenerallynotacceptedcorrelationsforthequali"cationTuesday1 stMarch,2016:19:32,Page70of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONofPWRstrainersforseveralreasons.Pleaseexplainwhythefollowinggeneralconcernswiththeuseofcorrelationsarenotanissueforthe STPapplication:(a)Correlationshavenotbeenvalidatedforthefullrangeofdebrisloadsandmorphologiespresentunderplantconditions.RemovedResponse,Pg.71(b)Correlationsdonotaddressnon-homogeneousdebrisbedswhichareverylikelytooccurduetotransporttimingandnon-homo-geneous"lteringofdebriswithinthebed.RemovedResponse,Pg.307(c)Correlationshavenotbeenvalidatedforthefullrangeofpotential"owconditionsandstrainergeometriesthatarepresentinplants.RemovedResponse,Pg.307(d)Thereissigni"cantuncertaintyinthemodelparametersusedtodescribethephysicalattributesofthedebrisbedconstituents.RemovedResponse,Pg.30916.TestingperformedtovalidatetheNUREG/CR-6224 1correlationforspeci"cSTPconditionsdoesnotappeartoaccomplishthepurpose

(

References:

Volume3,Section5.6.2,"ConventionalDebrisHeadLoss Model,"andVolume6.2,Item5.a.10).Additionally,theNRC doesnothavecompleteinformationtoconcludethatthetestingad-equatelyrepresentedtheplantcon"gurationandrangeofconditions thatcouldoccuratSTPfollowingaLOCA.Therefore,thewas unabletodeterminethattheplantspeci"cverticallooptestsresults wererepresentativeofheadlossesthatcouldoccurfromadebrisbed onaprototypicalmodule.Thecorrelationresultsandthesinglever-ticallooptestresultthatmodeledtheJuly2008Alden"umetest underSTPspeci"cconditionsweresigni"cantlytfromeach other,andfromtheresultsofthe"umetest.Thatis,allthreeresults, althoughmodelingsimilarconditions,hadsigni"cantlytre-sults.Thesubmittalexplainedastowhytheresultsweresubstantially t,buttheexplanationwasnotcon"rmedbytestingorbyuse ofacceptedtheories.Industryheadlosstestsusingsimilarsurrogates onprototypicalstrainermodulesresultedinsigni"cantlyhigherhead lossesthanthosereportedbySTPfortheirverticallooptestingand thosecalculatedbyuseofthecorrelation.Theisconcernedthat verticallooptestandmoduletestresultsfromtestsconductedun-dersimilarconditionsmayduetothedbetweendebris characteristicsinverticallooptestandmoduletestdebrisbeds.These couldbecausedbydintransportanddeposition ofthedebrisontotheperforatedsurfaces.Therefore,theiscon-cernedthatthevalidationtestingisnotrepresentativeoftheplant.

Pleaseprovidethefollowingadditionalinformation:(a)IftheverticallooptestsconductedbySTPareimportanttotheconclusions,pleaseprovidedetailsastowhytheSTPverticalloop testsarevalidconsideringthatothermoduletestsconductedin severaltfacilitiesundersimilarconditions,debrisloads, anddebrischaracteristicshadsigni"cantlytresults.RemovedResponse,Pg.310 1NUREG/CR-6224,ParametricStudyofthePotentialforBWRECCSStrainerBlock-ageDuetoLOCAGeneratedDebris,"FinalReport,October1995(ADAMSAccessionNo.

ML083290498).Tuesday1 stMarch,2016:19:32,Page71of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)IftheverticallooptestsconductedbySTPareimportanttotheconclusions,pleaseprovideevidencethatverticallooptests conductedundersitespeci"cconditionswillcorrelateto"ume testsconductedundersimilarconditionsortoheadlossesthat wouldoccurintheplant.Pleaseincludeinformationregarding howitwasdeterminedthatthedebristhattransportedtothe horizontalstrainersurfaceresultedinadebrisbedofsimilarchar-acteristicsandmorphologytothatwhichwouldtransporttothe plantstrainer.Pleasestatehowwasitdeterminedthatthehead losseswouldbecomparable.RemovedResponse,Pg.311(c)Pleaseprovideinformationthatdemonstratesthatthecorrela-tionusedbySTPisvalidforplantspeci"cstrainergeometries andplantspeci"cconditions.Alternately,pleaseprovideabasis forusingacorrelationthathasnotbeenvalidatedspeci"callyfor STPplantconditionsandgeometries.RemovedResponse,Pg.312(d)PleasediscusshowtheNUREG/CR-6224correlationcouldbeusedtopredicttheheadlossesthatwouldbeexpectedunder conditionssimilartothoseinthetwo"umetestsconductedby STPinFebruaryandJuly2008.RemovedResponse,Pg.31217.ThesubmittalstatesthatalltestingperformedtovalidatetheNUREG/CR-6224correlationwasboundedbycorrelationpredictions(

References:

Volume1,Section1.2.7,ConventionalHeadLossModel,andVol-ume3,Section5.6.2,ConventionalDebrisHeadLossModel).There havebeennumerouscaseswherethecorrelationseverelyunder-predicted headlossesthatwerecarriedoutundercarefullycontrolledcon-ditions.NUREG-1862,DevelopmentofPressureDropCalculation MethodforDebris-CoveredSumpScreensinSupportofGenericSafety Issue191,February2007(ADAMSAccessionNo.ML071520440),

andNUREG/CR-6917,ExperimentalMeasurementofPressureDrop AcrossSumpScreenDebrisBedsinSupportofGenericSafetyIssue 191,February2007(ADAMSAccessionNo.ML071910180),con-taindatathatshowthattheNUREG/CR-6224correlationisnot conservativeinallcases.TheseNUREGsdeterminedthatcorrelation predictionsarehighlydependentontheparametersusedtodescribe thephysicalattributesofthedebrisbedconstituentsandthatthese parametershavesigni"cantuncertainty.TheseNUREGsalsodeter-minedthatheadlossesarenotwellpredictedbyacorrelationthat assumesahomogenousdebrisbed.Someoftheexperimentaldata involved"nedebris,microporousdebris,non-homogeneousbeds,and otherconditionsthattheNUREG/CR-6224correlationisnotde-signedtoaccountfor.Itisverylikelythatsomeconditionsthat NUREG/CR-6224correlationdoesnotaccountfor,maybepresent underplantpost-LOCAconditions.Thesubmittalstatesthatthe headlosscorrelationfromNUREG/CR-6224hasbeenextensively validatedforvariousconditions.TheNRCisoftheopinionthat thereislittleornotestingthathasbeenconductedundercondi-tionssimilartothoseatSTP.Theisconcernedwiththevali-Tuesday1 stMarch,2016:19:32,Page72of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONdationissueslistedbelowwhenusingacorrelationforquali"cationofstrainers.PleasestatehowtheSTPevaluationaccountsforthese uncertaintiesandlackofvalidationofthecorrelationunderplant

conditions.(a)Debrisconstituentsinvalidationtestingarenotplant-speci"cRemovedResponse,Pg.313(b)Debrissizesinvalidationtestingarenotplant-speci"c.RemovedResponse,Pg.314(c)VerylittlevalidationtestingwasconductedatSTPvelocitiesandnonevalidatedthecorrelation.RemovedResponse,Pg.314(d)Validationtestingdidnotincludeprototypicalstrainergeome-tries.RemovedResponse,Pg.314(e)Validationtestingperformedinverticalloopsdoesnotsimulatepotentiallyimportantaspectsofdebrisbedformationunderplant

conditionsRemovedResponse,Pg.314(f)Therecordsofearlyvalidationtestingarenotavailableordonotcontaintheinformationrequiredtodeterminewhetherthe testswereconductedtoadequatelyrepresentplantconditions.

Therefore,conclusionsfromearlytestingmustbelimited.RemovedResponse,Pg.31518.TheimplementationofthecorrelationintheSTPmodelmakesspe-ci"cassumptionsandmaypotentiallycontainmodelingerrorsthat cansigni"cantlytheresultsofthecalculation(

References:

Vol-ume3,Assumptions7.b,7.e,and7.f;Volume3,Section5.6.2,Con-ventionalDebrisHeadLossModel;Volume6.2,Item5.a.10;and Enclosure6,Table1).Pleaseprovidethefollowinginformationto justifythattheassumptionsanduseofthecorrelationisrealisticor conservativeforSTPplant-speci"cconditions.(a)Pleaseprovidejusti"cationthatthebedsarehomogeneousrep-resentativeoftheplant(Volume3,Assumption7.eandVolume 6.2,Item5.a.10).RemovedResponse,Pg.315(b)Itisassumedthat"berglassdebriswouldaccumulateuniformlywithadensityof2.4poundspercubicfoot(lb/ft3).TheNRC isoftheopinionthatassumingthedebrisbeddensitytobe thesameasthemanufactureddensitymaynotbeanaccurate assumptionandisbasedontheobservationofdebrisbedsformed inindustrytestsandNUREG-1862testing.TheNRCisfur-theroftheopinionthatintheplant,only"neandsmall"berwill transportandcollectatamuchhigherdensity.Pleasedescribe whythedensityassumptionisvalidandwhyitdoesnotsig-ni"cantlytheresults.Alternately,re-performtheanalysis withadensitythathasbeenshowntobeappropriate.(Volume 3,Assumption7.fandSection5.6.2andVolume6.2,Item5.a.1

0).RemovedResponse,Pg.315(c)PleaseexplainhowtheNUREG/CR-6224correlationcompres-sionfunctionisappliedintheSTPmodel.NUREG-1862found thatthecompressionrelationfromNUREG/CR-6224doesnot accuratelymodelthecompressionofthebed,especiallyatlow "owvelocitieslikethoseatSTP.(Volume3,Section5.6.2).RemovedResponse,Pg.316Tuesday1 stMarch,2016:19:32,Page73of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)ThesubmittalstatesthatSTPimplementedalinearmassweightedaverageinsteadofthevolumetricweightedaverageforimple-mentationofcompositesurfacetovolumeratio(S v)inthe6224correlation.Thesubmittalstatesthattherearemanypossible compositeweightingmethodsthatcouldbeused,butdoesnot justifythemethodchosenintheapplication.NEI04-07and NUREG/CR-6371,Blockage2.5ReferenceManual,Decem-ber1996(notpubliclyavailable),bothrecommendedthevolume weightingmethod.Pleaseexplainwhymassweightingisaccept-able.Pleaseexplainifboththemethodsresultinsigni"cantly tresults.(Volume3,Section5.6.2andEnclosure6).RemovedResponse,Pg.317(e)PleaseprovideatechnicalbasisforAssumption7.bregardingcoatingmaterialpackingfractions.Pleasediscusstheof theassumptiononresults.Pleaseprovidethepotentialrangesof packingfactorsforcoatingmaterials.(Volume3,Assumption7.b andVolume6.2,Item5.a.10).RemovedResponse,Pg.31719.Theapplicationofamultiplierof"ve(5x)totheresultoftheheadlosscorrelationusedintheSTPmodelappearstoindicateuncer-taintyintheabilityofthecorrelationtopredictheadlossescorrectly

(

References:

Volume1,Section1.2.7andVolume3,Section5.6.2).

IftheNUREG/CR-6224correlationisarobustmodelasimpliedin thesubmittal,theNRCisoftheopinionthatitisunnecessary tousesafetyfactorsintheheadlosscalculationsforachievingreal-isticresults.ThenotedthatsomePNNLtestingshowedthat the6224correlationunderpredictedheadlossbymorethanafactor of5X.Pleaseprovidejusti"cationforapplyingthemultipliertothe resultsoftheheadlosscorrelation.RemovedResponse,Pg.31720.Thesubmittalassumesthatpaintchipsorotherrelativelylargedebristhatmayreachthestrainercanbeaccountedforinthecorrelationas sphericalparticles(

Reference:

Volume3,Section5.6.2).Largedebris mayfullyorpartiallyblockstrainerperforationsandmaydeposit non-homogeneouslyonthestrainer.Pleaseprovideanexperimental basistocon"rmthatpaintchips(orotherlargeparticles)maybe accuratelymodeledinthecorrelation,includingtheassumptionthat theycanbeaccuratelymodeledassphericalparticles.Intheabsence ofanexperimentaljusti"cation,pleaseprovideanalternatebasisfor theSTPtreatmentofpaintchipsandotherlargeparticlesintheheadlosscorrelation.RemovedResponse,Pg.31821.TheSTPcorrelationusesphysicalpropertiesofmaterialspredictedtobeinthedebrisbedinordertocalculateaheadloss(

References:

Volume3,Section5.6.2,ConventionalDebrisHeadLossModel, andVolume6.2,Item5.a.10).ResultsfromtheNUREG/CR-6224 correlationareheavilydependentupontheaccuraterepresentation ofmaterialphysicalproperties.Oneofthemostparameters toaccuratelydetermineisthesurfacetovolumeratio(S v).Pleaseprovidethefollowinginformation:(a)PleasestatehowS vvaluesweredeterminedforeachmaterial.RemovedResponse,Pg.319Tuesday1 stMarch,2016:19:32,Page74of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Itisknownthatforsomedebristypes,andpossiblyalldebristypesexpectedtobepresentinPWRdebrisbeds,physicalmea-surementscannotprovideS vvaluesthatallowaccuratepredic-tionofheadlossinexistingcorrelations.Thiswasespeciallyev-identformicroporoustypematerialsandwasshowntobetrue forothermaterialsbyNUREG-1862.Pleaseexplainthebases fortheS vvaluesandothermaterialpropertiesusedintheSTPimplementationofthecorrelation.RemovedResponse,Pg.319(c)Pleasestatehowtheuncertainty,describedonpage184ofVol-ume3,iscausedbytherelationshipbetweenexperimentallyde-ducedS vvaluesandheadloss,accountedforintheSTPmodel.RemovedResponse,Pg.319(d)TheNRCdoesnotagreewiththestatement,onpage185ofVolume3,whichstatesthatthelackofagreementbetween thecorrelationandtestresultsusinggreensiliconcarbideand tindonottheSTPcalculations.ItappearsthatSTPhad ydeterminingparameterstoinputtothecorrelationto attainaccurateresults.Pleaseprovidebasisfortheconclusion thatthelackofagreementbetweenthecorrelationresultsand testresultsdonotSTPheadlosscalculations.RemovedResponse,Pg.32022.TheNUREG/CR-6224correlation,andothersimilarcorrelations,usespeci"csurfaceareas(S v)forcylindricalobjectsassumingthatthe"berisorientedperpendiculartothe"owandthatthe"bershavea uniformdiameter.ThisassumptionisusedintheSTPmodel(Refer-ence:Volume1,Section1.2.7,ConventionalHeadLossModel,and Volume3,Section5.6.2,ConventionalDebrisHeadLossModel).

NUREG-1862calculateddtspeci"csurfaceareasforvarying diametersofNukonandnotedainS vbetween"bersthathadbinderandthosethatdidnot.TheNUREGalsoestimatedthe

S vofNukon"bertobearound250,000to300,000ft 1insteadof 180,000ft1whencorrectedfortestdata.(STPusesfortheS v of 571,429m1 (174,172ft 1)forNukon"ber.)PleaseexplainhowtheSTPevaluationtakesthese"ndingsintoaccount.(Volume3,Section

5.6.2).RemovedResponse,Pg.32023.TheSTPNOCsubmittalmakestheassumptionthatMicrotherm"berswillhavepropertiessimilartothoseofNukon(bulkdensity=2

.4lbm ft 3 ,microscopicdensity=165 lm ft 3andS v=666 , 667 m1)(

Reference:

Vol-ume3,Section5.6.2).Pleasestatethebasisforthisassumption.Also,pleasejustifytheuseoftheNukon"berbulkdensityasthedebris beddensity.RemovedResponse,Pg.32124.Thephysicalcharacteristicsusedintheheadlosscorrelationcanhaveasigni"cantontheresultsoftheheadlosscalculations.Char-acteristicvaluesthatdescribetheassumedbehaviorofSTPdebris areprovidedinTables5.6.1and5.6.2ofVolume3.NRCresearch conductedforNUREG-1862hasdeterminedthatsomeofthevalues thatdescribethephysicalcharacteristicsofdebrisarenotwellun-derstood.PleaseprovidethebasesforthevaluesinTables5.6.1and 5.6.2.PleaseprovidereasonableuncertaintybandsforthematerialTuesday1 stMarch,2016:19:32,Page75of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproperties.Also,pleaseexplainhowcompoundedinaccuraciesinas-sumedmaterialpropertieswouldtheheadlossvaluespredicted bythecorrelation.RemovedResponse,Pg.32125.Volume3,Assumption7.f,statesthatitisassumedthat"berglasswillaccumulateuniformlyonthestrainersbutalsostatesthatthe amountofdebristhatcancollectonthebottomofthestraineris limitedtotwoinches.Thisassumptionseemstocontradictitself.(a)Pleaseexplainhowtheassumptionisaccountedforinheadlosscalculationsorprovideinformationthatshowsitisnotsigni"cant totheresults.Pleaseexplainhowanon-uniformaccumulationof "brousdebris,limitedbythe"oororpoolheight,would theheadlosscalculation.RemovedResponse,Pg.211(b)PleaseprovideanevaluationofhowthisAssumption7.e.ofVolume3regardinghomogeneousbedformation.RemovedResponse,Pg.21226.Thesubmittalcalculatescircumscribedbedsurfaceareasbasedondebrisloading(

Reference:

Volume3,Section5.6.2).Pleaseprovide thefollowinginformation:(a)Pleasestateifareascalculatedforbedstransitionedfromthinbedtocircumscribed.RemovedResponse,Pg.212(b)When"brousdebrisisdepositedonthestraineritsdensitywillbesigni"cantlyincreasedfromthemanufacturedvalue.Please statehowwasthisaccountedfor(Volume3,Page696,Section

5.6.2).RemovedResponse,Pg.212(c)Pleaseclarifyifthereareanyobjectsaroundthestrainerthatwouldpreventthedebrisbedfromaccumulatinguniformlyas assumedinthestrainerloading(Volume3,Table5.6.3).

RequiredResponse,Pg.212(d)TheNRCisoftheopinionthatitisnotrealistictoassumethethicknessofthedebrisbedonthestrainercanbesuchthat itwillexceedtheheightofthewaterlevelinthepool.Please explainhowthisthedebrisloadingcalculation(Volume 2,Section5.6.2).RemovedResponse,Pg.213(e)Pleasestatehowoftenthedebrisloadingalgorithmresultsinacircumscribedbedoronethatistransitioningtocircumscribed (fullyorpartially"lledinterstitialvolume).RemovedResponse,Pg.215(f)Pleaseexplainthesigni"canceofcasesthatresultintheintersti-tialvolumeofthestrainerbecomingpartiallyorcompletely"lled withdebris.RemovedResponse,Pg.21727.Thesubmittalstatesthatthecleanstrainerheadloss(CSHL)is0.220ft.basedonatest(

Reference:

Volume3,Sections2.2.23,Clean StrainerHeadLoss,and5.6.1,CleanStrainerHeadLoss).Itap-pearsthatthevaluewastakenfromatestthatwasconductedus-ingasinglemodule.TheCSHLshouldbere"ectiveoftheentire strainerincludingallmodulesandconnectingpiping,"ttings,etc.IntheSTPNOCletterdatedDecember11,2008(ADAMSAccessionNo.

ML083520326),theCSHLwasstatedtobe1.95ft.PleaseexplainwhyTuesday1 stMarch,2016:19:32,Page76of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthevalueprovidedintherisk-informedsubmittalissigni"cantlydif-ferentfromthepreviouslycalculatedvalueandverifythatitincludes allheadlossesassociatedwiththeentirecleanstrainertrain.

RequiredResponse,Pg.32328.Consideringtheindividualuncertaintiesthatresultfromtheissuesdescribedintherequestforadditionalinformationonthesubjectof headloss,pleaseprovidejusti"cationthattheuseofacorrelationis acceptableintherisk-informedmodel.Alongwiththejusti"cation, pleaseprovideananalysisoftheoveralluncertaintyandstatehow thiswillbeincorporatedintotheoverallrisk-informedevaluation.RemovedResponse,Pg.323

• NPSHandDegasi"cation29.Volume1,Section1.1,StructuredInformationProcessFlow,andVolume3,Sections2.2.28,PumpGasLimits,and5.7.4,Accep-tanceCriterion:PumpGasVoidLimits,describethemethodology forcalculatingNPSHmargin.Thesubmittalstatesthatifthevoid fractionexceeds2percentthatthescenarioisrecordedasafailure.

ItisnotclearthatNPSHRequired(NPSHR)iscorrectedforde-gasi"cationthatmayoccuras"uidpassesthroughthedebrisbedas recommendedbyRG1.82,Revision4,WaterSourcesforLongTerm RecirculationCoolingFollowingaLoss-of-CoolantAccident,Revi-sion4,March2012(ADAMSAccessionNo.ML111330278).Please clarifywhetherNPSHRiscorrectedforthevoidfractionatthepump inlet.IftheNPSHRisnotcorrectedforthevoidfraction,pleasepro-videajusti"cation.

RequiredResponse,Pg.17730.TheSTPNOCsubmittalstatesthatthedegasi"cationcausedbythepressuredropthroughthedebrisbediscalculatedtodetermineif apumpfailurecriterionismet(

References:

Volume1,Section1.1, StructuredInformationProcessFlow;Volume3,Assumptions8a.

throughi.;Volume3,Section5.7.2,Degasi"cation;andEnclosure 6,Table1).Pleasestateifthedegasi"cationcalculationcreditscon-tainmentaccidentpressure.Ifso,pleaseexplainhowthepressurefor eachcaseorconditioniscalculated.Pleasestatewhattemperatureis usedforthedegasi"cationcalculationandhowthistemperaturewas calculatedforeachcase.

RequiredResponse,Pg.21731.TheSTPNOCsubmittaldoesnotseemtoevaluatethepossibleofthecollectionofgasbubblesinthestrainerorECCSpumpsuction piping(

Reference:

Volume3,Assumption8.h.andSection5.7.3,Gas TransportandAccumulation).Pleaseexplainhowitwasdetermined thatgasbubbleswouldnotcollectinthestrainer,orpipingbetween thestrainerandECCSandCSSpumpsandeventuallytransportas largevoids.Ifgaspocketscanbecometrappedintheselocations, pleaseexplainits RequiredResponse,Pg.21732.TheNRCcouldnotdeterminewhetherthecalculationofNPSHAvailable(NPSHA)includescontainmentpressuregreaterthanthe saturationpressureofthesump"uid.Volume3,Assumption1.cin-dicatesthatcontainmentpressuregreaterthanthesaturation(aboveTuesday1 stMarch,2016:19:32,Page77of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION14.7poundspersquareinchabsolute(psia))isnotcreditedintheNPSHcalculations(

Reference:

Volume1,Section1.1,Structured InformationProcessFlow;Volume3,Sections3,Assumptions, and5.7.2,"Degasi"cation";andEnclosure6,Table1).Pleaseclarify ifthecalculationforNPSHAincludescontainmentpressureabove thesaturationpressureofthe"uid.Ifcontainmentpressuregreater thanthesaturationpressureofthe"uidiscreditedintheNPSHA calculation,pleaseprovidejusti"cationforitsuseandprovidethe methodologyusedtocalculatethecontainmentpressureandsump "uidtemperatureforeachcase.

RequiredResponse,Pg.21733.ThepoolwaterlevelcalculationprovidedintheSTPNOCsubmittaldoesnotappeartoaccountforchangesinpoolareawithelevation orchangesinobjectsthatmaydisplacewater(

Reference:

Volume3, Section2.2.5,"PoolWaterLevel").Pleasestateiftherearesigni"cant changesinareaorobjectsinthepoolthatcouldwaterlevel.If so,pleasedemonstratethatthemethodologyusedtocalculatepool levelisrealisticorconservative.

RequiredResponse,Pg.32434.Thesubmittallistsminimumandmaximumvaluesforcontainmentspray"owrates(

Reference:

Volume3,Section2.2.8,ECCSandCCS FlowRates).Pleasestatehowthesevaluesareusedintheevaluation.

If"owratesotherthanthemaximumareused,pleaseexplainhow theappropriate"owratewasdeterminedforeachcase.Required(strnr.pen.)Response,Pg.21835.TheSTPNOCsubmittalcalculatesanequivalentbreaksizeof38.9inchesfora27.5inch-DEGBinVolume3,Section2.2.8.Pleasede-scribehowtheequivalentbreaksizeof38.9incheswascalculatedand whyitwasnecessarytocalculatethisvalue.RemovedResponse,Pg.21836.ThesubmittalstatesthattheNPSHRfortheECCSandCSSpumpsis12ft(

Reference:

Volume3,Section2.2.24,"PumpNPSHMargin,"

andEnclosure6,Table1).TheproposedUFSARrevisions(pages9 and11ofAttachment2toEnclosure3)statethattheNPSHRforthe pumpsisbetween16.1and16.5ft.ApreviousSTPNOCsubmittal datedDecember11,2008(ADAMSAccessionNo.ML083520326),

forresponsetoGenericLetter(GL)2004-02statedthattheNPSHR valuesfortheLHSI,HHSI,andCSpumpsare16.5ft.,16.1ft.,and 16.4ft.,respectively.PleaseprovidethebasisfortheNPSHRvalues usedinthecurrentevaluation.

RequiredResponse,Pg.325

• In-VesselandBoricAcidPrecipitation37.TheSTPNOCsubmittaluses7.5gramsperfuelassemblyasthe"beracceptancelimitforcold-legbreaks(

References:

Volume1,Section 1.1,StructuredInformationProcessFlow,Step18;Volume1,Sec-tions1.2.10,BoricAcidPrecipitation,and1.2.11,In-VesselFiber Limits;Volume3,Assumption11.b;Volume3,Section4.2,Struc-turedInformationProcessFlow,Step18;Volume3,Section5.11.2, AcceptanceCriteria:DebrisLoads;andVolume6.2,Items5.a.13 and5.a.15).TheNRCstatedinitsSEon"EvaluationofLong-TermCoolingConsideringParticulate,Fibrous,andWCAP-16793,Tuesday1 stMarch,2016:19:32,Page78of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRevision2,"ChemicalDebrisintheRecirculationFluid,"October2011(ADAMSAccessionNo.ML13084A154),thatthemaximum amountof"berthatwouldbepresentinthelimitingreactordesign followingacold-legbreakwouldbeexpectedtobeabout7.5grams, ifthehot-legbreak"beramountdidnotexceed15grams.The didnotconcludethata"berloadof7.5gramswasadequatetoen-surethatboricacidprecipitationwouldnotoccur.Theamountwas projectedasthepotentialmaximumintheshorttermuntilindustry completedaseparateprogramonboricacidprecipitation(BAP).In itsevaluation,theconsideredthattheplantcalculationofthe in-vesseldebrisloadincludedtheworstcasedebrisloadfortheplant andthatmostplantswouldhavemuchlessthan7.5gramsofde-brisfollowingacold-legbreak.NotethattestingfortheWCAPdid showthatthe"owrequiredtomatchdecayheatboilwouldreach thecorefollowingacold-legbreakwithdebrisloadsgreaterthan7.5 grams,butdidnotshowthatmixingcreditedtopreventBAPwould notbeThelimitof7.5gramsperfuelassemblyhasnotbeen technicallyjusti"edasanacceptancecriterionforBAP.Pleasepro-videthetechnicalbasisforassumingthat7.5gramsisanacceptable limitforacold-legbreakatSTPwhenconsideringthepotentialfor boricacidprecipitation.

RequiredResponse,Pg.218

• DebrisBypass38.Thesubmittaldiscussesthefractionofdebristhatis"sheddable"fromadebrisbed(

Reference:

Volume3,Section5.8,"DebrisPenetration").

PleaseexplainifVn,(Fractionofdebristhatissheddable),isa simplefractionoritisdependentontheamountofdebrisinthebed.

RequiredResponse,Pg.32739.ThesubmittalstatesthatdebrisbypassorpenetrationtestingwascompletedtosupportmodelingofthebypassofdebrispasttheSTP strainer(

Reference:

Volume6.2,Item5.a.16).Pleaseprovideaddi-tionaldetailsonhowdebrispenetrationtestingfor"berwascon-ducted.Speci"cally,pleaseprovidethefollowinginformation:(a)Providedetailsonthecharacteristicsofthe"berthatwasaddedtothetestfacility.i.Howthe"berwasprepared.ii.Statewhatthepercentageswereofeach"berclassi"cationasdescribedinNUREG/CR-6808,"KnowledgeBaseforthe ofDebrisonPressurizedWaterReactorEmergency CoreCoolingSumpPerformance,"February2003(ADAMS AccessionNo.ML030780733),Table3-2afterthe"berwas

prepared.iii.Howwasitensuredthatagglomerationofthe"berdidnotoccurpriortoadditiontothetestloop?

RequiredResponse,Pg.219(b)Forteststhathadmorethanonebatchof"beraddedtothetest,pleasestatewhatthetimingwasofeachdebrisaddition.

RequiredResponse,Pg.221(c)Pleasedescribethedesignofthetestfacility.

RequiredResponse,Pg.221Tuesday1 stMarch,2016:19:32,Page79of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Wasthecirculationof"uidwithinthetankturbulent?Diddebrissettle?Ifsomedebrisdidnotreachthestrainer,howwasthis accountedfor?

RequiredResponse,Pg.222(e)Howwasitensuredthat"berdidnotbypassthe"ltersduringthetest?RequiredResponse,Pg.222(f)Wasthedesignofthestrainerandthedesignofthetestfacility("owrate,etc.)prototypicalwithrespecttotheSTPstrainer?

RequiredResponse,Pg.222

• DefenseInDepthandMitigativeMeasures40.Volume1,Section2.1.1,Defense-in-Depth,statesthattheconcernsraisedinGSI-191havenobearingoncontainmentintegrityoron thereleaseofradiation(page18ofVolume1).Volume1,Appendix C,pageC6statesthattheindependenceofbarriersisnotdegraded.

TheNRCnotesthatbarrierindependenceisafunctionofmulti-plefactors(e.g.,plantoperations,maintenance,environmentalcondi-tions)thatarenotnecessarilylinkeddirectlytoSSEdesign.Appendix Cpresentsasimilarargumentwithrespecttomaintainingabalance amongcoredamageprevention,containment,andconsequencemiti-gation.ItisnotcleartotheNRCthatalackofdesign/equipment changescanbeequatedunconditionallywithabalancedapproachto prevention,containment,andmitigation.Thepresenceofdebrismay impacttheenessofcoredamagepreventionandcontainment simultaneously.Implementationofadeterministicsolutionwouldre-sultinzeropredictedfailuresofthefuelorcontainmentasaresult ofdebris,followinganassumedfailureoftheRCSbarrier.STPs risk-informedsolutionpredictsthatsomefuelorcontainmentfailures mayoccur.Thisimpliesthattheindependenceofbarriersmaybede-gradedundertherisk-informedapproach.ConsistentwithRG1.174, pleaseprovidediscussionondefenseindepthcontainedinAppendix C,usingquantitativeassessmentstotheextentpracticable(tosup-plementtheexistingqualitativeassessment),todemonstratethatthe elementsofdefenseindepthdescribedbyRG1.174aremet.Where appropriate,provideacomparisonbetweenthehypotheticalclean plantandtheas-built,as-operatedplant.ConsistentwiththeRG, pleasealsoincludeanevaluationoftheproposedchangeon equipmentfunctionality,reliability,andavailability.

RequiredResponse,Pg.32741.Volume1,AppendixC,SectionC.5.4,listsmitigativemeasuresthatcanbetakenifthestrainerbecomesblocked.Itisnotclearhowthe mitigativemeasuresidenti"edtoaddressstrainerblockageareimple-mentedatSTP(notethattheseactionsarealsocreditedforpreven-tionofinadequatecore"ow).Pleaseexplainthefollowingtoexplain howthemitigativemeasuresarecapableofprovidingalternate"ow totherequiredequipment.(a)Themitigativeactionsidenti"edtoreduce"owthroughthestrain-ersappeartoactuallybedesignedtoconserveRWSTvolume.

Thesemeasuresmaydelaytheinitiationofrecirculation,but exceptforsecuringCSSpumpswillnotreduce"owthroughTuesday1 stMarch,2016:19:32,Page80of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthestrainer.Pleasestateatwhatpointintherecoverytheseactionsareperformed.Ifnotperformedimmediately,willthe RWSTinventorybeconserved?Ifthereductionsof"owthrough thestrainerdonotoccuruntilafterstrainerblockageisevident, pleasestateiftheseactionsaree.

RequiredResponse,Pg.223(b)PleasestateifSTPhasimplementedoperatingprocedurestosecurethethirdtrainofECCS/CSSifallthreeareinitiatedfol-lowingaLOCA.

RequiredResponse,Pg.224(c)PleaseclarifyifSTPimplementedoperatingproceduresorotherguidancetobackwashthestrainers,ifnecessary.Ifso,please providedetailsontheproceduralcontrolsforthisaction.

RequiredResponse,Pg.224(d)PleasestatewhentheRWSTre"llisstartedandhowlongittakestore"llRWSTtothepointwhereinjectionfromthetank isviable.Pleasenotethatifthetankisnotreadyforinjection whenblockageoccurs,thisactionmaynotbee.TheNRC notesthattheSTPNOCsubmittalstatesthatmoststrainer blockageeventsoccurwithinthe"rst24hoursoftheLOCA recovery.RequiredResponse,Pg.22442.Volume1,AppendixC,SectionC.5.8,MitigationofInadequateRe-actorCoreFlow,listsmitigativemeasuresthatcanbetakenifthe "owtothecoreisnotadequatetoensurecorecooling.Itisnotclear totheNRChowthemitigativemeasuresforinadequatereac-torcore"owwillbee.Mostoftheactionsattempttoinject coolantthroughthe"owpaththathasalreadybeenidenti"edaspo-tentiallyblocked.Otheractionsdonotappeartobeeifthe coreinletisblocked.Pleaseprovideadditionalinformationshowing thatthemitigativemeasuresarecapableofprovidingcoolanttothe

core.RequiredResponse,Pg.3291.3.10STSB:TechnicalSpeci"cationsBranch1.TheproposedLARprovidesassumptionsofpartial"owreductionofcer-tainECCSequipmentduringDBAevents.Pleaseexplainhowthepro-posedLARECCS"owassumptionsarewhentheCon"guration RiskManagementProgram(CRMP)TechnicalSpeci"cation(TS)Com-pletionTimesareappliedtoTSinoperableECCSSSCs.Includeinyour discussion,howtherelatedECCSequipmentPRAfunctionality(asde-

"nedinNEI06-09,Revision0,Risk-InformedTechnicalSpeci"cations Initiative4b,Risk-ManagedTechnicalSpeci"cations(RMTS)Guidelines, November2006(ADAMSAccessionNo.ML12286A322))isincludedinthe analysisandhowtheanalysisassumptionsareprogrammaticallyincluded theCRMP.RequiredResponse,Pg.1772.TheSTPCRMPcouldallowcontinuedpoweroperationwithalossofaTSsafetyfunctionforupto30days.PleaseexplainhowaTSlossoffunction, butPRAfunctional(asde"nedbyNEI06-09,Revision0)ECCSSSGis addressedintheanalysis.

RequiredResponse,Pg.178Tuesday1 stMarch,2016:19:32,Page81of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION3.Pleaseexplainhowtheassumptionsandanalysisfor"brousmaterialim-pactonECCS"owareveri"edandmaintainedprogrammatically(i.e.,

howandatwhatfrequencyareanyphysicalormaterialchangestothe analyzedimpactzonesevaluatedandwhatphysicalormaterialchanges wouldinitiateareevaluationoftheimpactzone).

RequiredResponse,Pg.179Tuesday1 stMarch,2016:19:32,Page82of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.4Round2RAIs1.4.1APLA:ProbabilisticRiskAssessment(PRA)LicensingBranch (APLA)*ProjectQualityAssuranceRegulatoryGuide(RG)1.174,Revision2,AnApproachforUsingProb-abilisticRiskAssessmentinRisk-InformedDecisionsonPlantSpeci"c ChangestotheLicensingBasis,May2011(ADAMSAccessionNo.ML100910006),Section5,"QualityAssurance,"providestheNRCsposi-tiononqualityassurance(QA)requirementsforrisk-informedchangesto thelicensingbasis.Speci"cally,thissectioncontainsseveralprovisionsthat shouldbemetwhenalicenseeelectstousePRAinformationtoenhance ormodifyactivitiesthesafety-relatedfunctionsofstructures, systems,andcomponents(SSCs).WhenreferringtoQA,thetermactiv-itiesistypicallyinterpretedtomeandesigning,purchasing,fabricating, handling,shipping,storing,cleaning,erecting,installing,inspecting,test-ing,operating,maintaining,repairing,refueling,andmodifying.Therefore, theproposeddecisionnottoremoveproblematicinsulationrepresentsa modi"cationtoseveralactivitiesthesafety-relatedfunctionsof SSCs,namelytheEmergencyCoreCoolingSystem(ECCS)andContain-mentSpray(CS)systems.1.PleasedescribehowPRAinformationthatisusedtojustifynotre-movingproblematicinsulationincludingbutnotlimitedtothePRA, CASAGrande,andsupportinganalysesmeetsthefollowingprovi-sionsinRG1.174,Section5:

-Usepersonnelquali"edfortheanalysis.

-Useproceduresthatensurecontrolofdocumentation,includ-ingrevisions,andprovideforindependentreview,veri"cation, orcheckingofcalculationsandinformationusedintheanalyses.

-Provide(s)documentationandmaintain(s)recordsinaccordancewiththeguidelinesSection6ofRG1.174.

-Use(s)proceduresthatensurethatappropriateattentionandcor-rectiveactionsaretakenifassumptions,analyses,orinformation usedinpreviousdecisionmakingarechanged(e.g.,licenseevol-untaryaction)ordeterminedtobeinerror.

RequiredResponse,Pg.3372.TheLAR,Volume1describessomequalityassuranceactivitiesthatwereimplementedinsupportoftheLARbutstatesthatCASA GrandeisaproprietaryMATLABapplication,whichwasunavail-abletothe[quality]oversightteam.Therefore,pleaseprovideabrief summaryofthesoftwareQA(SQA)programforCASAGrandeand theanticipateddatewhentheCASAGrandesoftwarewillbecome compliantwiththatSQAprogram.Describeanystandardsandupon whichtheSQAisbased.

RequiredResponse,Pg.3373.IdentifyanyQAprogramsthatwereemployedforanytraditionalengineeringanalyses/calculationsperformedinsupportoftheLARTuesday1 stMarch,2016:19:32,Page83of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONandstatewhethertheseprogramsmeet10CFR50,AppendixBrequirements.

RequiredResponse,Pg.3384.DescribetheQAprogramemployedbyeachvendororcontractorthatperformedcalculationsoranalysesusedtosupporttheLAR.

ExplainwhethervendorQAprogramswereassessedbySTPNOCfor compliancewithapplicableQArequirements.

RequiredResponse,Pg.338

• TreatmentofUnanalyzedPlantConditions1.RG1.200,Revision2,AnApproachforDeterminingtheTechnicalAdequacyofProbabilisticRiskAssessmentResultsforRisk-Informed Activities,Revision2(ADAMSAccessionNo.ML090410014),Sec-tion1.4,"PRADevelopment,Maintenance,andUpgrade,"statesthat plantinformationusedintheProbabilisticRiskAssessment(PRA)

(e.g.,expectedthermal-hydraulicplantresponsetodtstatesof equipment)shouldbeasrealisticaspossible.Verifythatthecondi-tionalsplitfractionvalues(i.e.,failureprobabilitiesusedbyPRA) forsumpfailureandin-vesselfailurearebasedonCASAGrande simulationsthatrepresentaccuratelyplantconditionsforeachacci-dentsequencerelevanttotheLAR,orjustifythatthechosenfailure probabilitiesareupperboundsforanyplantconditionsthatmight occurforagivenscenario.Forexample,forplantconditionswherea simulationisimpractical,unnecessary,ornotperformedforanyother reason,asplitfractionvalueof1.0shouldbeassignedoraqualitative argumentshouldbemadetoselectanexistingCASAGranderesult asbounding.BasedoninformationprovidedintheLARVolumes2 and3,thisapproachisalreadyemployedforpumpstates.Eachofthe 64pumpstatesidenti"edintheLARwereassignedconditionalsplit fractionvaluesforsumpandin-vesselfailurethatwerebasedon:

-CASAGrandesimulations(pumpstates1,22,9,26,43)

-QualitativeargumentsastowhyexistingCASAGranderesultsarebounding(the11boundedstates)

-Assignedaconditionalcoredamageprobabilityof1.0(48otherpumpstates)Asimilarveri"cationthatassignedfailureprobabilitiesarerealisticorboundingshouldbeappliedtoallotherunanalyzedplantconditions includingbutnotlimitedto:

-Numberofcontainmentfancoolersnotequalto6

-Failureofcontainmentisolation

-FailureofoperatorstosecureonetrainofCSearly

-FailureofoperatorstosecureremainingtrainsofCSlate

-FailuretoswitchtohotleginjectionpriortosecuringCStrains

-Failuretoswaptohotleg(HL)recirculation

-Failureofarunningpumpfollowingasuccessfulstart

-Failureofoneormoreresidualheatremovalsystemheatex-changersTuesday1 stMarch,2016:19:32,Page84of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONTherefore,providetheresultsofasystematicreviewofallaccidentsequencescontainingatopeventcorrespondingtooneoftheseven GSl-191failuremodes.Foreachsequence,provideoneofthefollow-

ing:(a)Con"rmationthatthesplitfractionsassignedtosumpandin-vesselfailurewerederivedfromCASAGrandesimulationsthat areconsistentwiththespeci"cplantconditionsassociatedwith thesequence(i.e.,availabilityofplantequipment,success/failure ofoperatoractions,etc.).(b)TechnicalbasisforconcludingthattheexistingCASAGrandesimulationprovidesresultsthatareapplicableorbounding(c)Con"rmationthattheconditionalsplitfractionvalueforsumporin-vesselfailureweresetto1.0fornon-analyzedcases.RemovedResponse,Pg.344

• HumanReliabilityAnalysis7.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpact oftheproposedchange.NRCletterdatedApril15,2014(ADAMS AccessionNo.ML14087A075),includesanumberofRAlsrelatedto thehumanreliabilityanalysis(HRA)usedintheriskassessmentand STPNOCresponsestoRAlsdescribeanumberofhumanactions thatareimportantduringaloss-of-coolant-accident(LOCA).Please describehowthedependencyamongmultiplehumanactions(both thoseinthecleanplantanddebrismodels)inthesamesequence wasassessedforthedebrisPRAmodel.RemovedResponse,Pg.344

• KeyAssumptions/KeySourcesofUncertainty1.RG1.200de"nesakeysourceofuncertaintyasanissuewherenoconsensusapproachormodelexistsandwherethechoiceofapproach ormodelisknowntohaveanontheriskpro"le(e.g.,CDF[core damagefrequency],LERF[largeearly1releasefrequency),

[deltaCDF],[deltaLERF])

2.RG1.174andNUREG-1855,Revision1,GuidanceontheTreatmentofUncertaintieswithPRAs inRisk-InformedDecisionmaking,March2013(ADAMSAccession No.ML13093A346),statethat"consensus"referstoanapproachor modelthathasapubliclyavailablepublishedbasisandhasbeenpeer reviewedandwidelyadoptedbyanappropriatestakeholdergroup.In addition,widelyacceptedPRApracticesmayberegardedasconsen-susmodels.Examplesincludetheuseoftheconstantprobabilityof failureondemandmodelandthePoissonmodelforinitiatingevents.

Finally,modelsthattheNRChasutilizedoracceptedforthespeci"c applicationinquestioncanalsobeconsideredconsensus.

2TheNRCspositionisthatcaseswhereaconsensusmodeldoesexist,butthelicenseechoosesanalternatemodelalsorepresentkeysourcesofmodeluncertaintyiftheyhavean ontheriskpro"le.Tuesday1 stMarch,2016:19:32,Page85of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRG1.200de"nesakeyassumptionasonethatismadeinresponsetoakeysourceofmodeluncertaintywhereatreasonablealternativeassumptionwouldchangetheplantsriskpro"le.RG1.200statesthatforeachapplicationthatcallsuponthisregula-toryguide,theapplicantidenti"esthekeyassumptionsandapprox-imationsrelevanttothatapplication.Thiswillbeusedtoidentify sensitivitystudiesasinputtothedecision-makingassociatedwith theapplication.Therefore,pleaseprovideatableorotherstructuredresponsethatlistskeysourcesofuncertainty.Foreachkeysourceofuncertainty, pleaseidentifythekeyassumption(s)thatweremadetoaddressitand provideeitherasensitivitystudyintermsofGDF,LERF, andLERForuseaqualitativediscussionastowhyatrea-sonablealternativeassumptionwouldnotcausetheriskacceptance guidelinesinRG1.174tobeexceeded.Thisresponseshouldaddress:(a)Lapproachforchemical(b)Headlosscorrelation(c)Successcriteriaforfuelblockageandboronprecipitation(7.5gramsperfuelassembly(g/FA))(d)Fiberpenetrationmodelforsumpstrainer(e)Theuseofgeometric,ratherthanarithmeticmeanaggregatedvaluesfromNUREG-1829,EstimatingLoss-of-CoolantAccident (LOCA)FrequenciesThroughtheElicitationProcess,April2008 (Volumes1and2:ADAMSAccessionNos.ML082250436and

ML081060300)(f)Thecontinuumbreakmodel(vs.doubleendedguillotinebreak(DEGB)onlymodel)(g)Thequantityandreleaserateofunquali"edcoatingsThere-sponseshouldevaluateeachoftheseareasone-at-a-timeand shouldincludeanaggregateanalysisthatquanti"estheinte-gratedimpactonGDF,LERF,andfromthe sensitivitystudiesthatwereperformed.RemovedResponse,Pg.344

• ValidityofAssumptiononPumpCon"gurations1.Inresponsetoquestion3,PlantCon"guration,oftheApril15,2014,RAI,STPNOCanalyzedtpumpcon"gurationsforCase 22toverifyAssumption2bofVolume3,whichstatedthatacombi-nationofpumpsfailinginthesametrainwouldresultinabounding failureprobabilitycomparedtoothercombinationswiththesame numberofeachtypeofpump(i.e.,highhead,lowhead,andCS).Theresultsofthissensitivityshowedthattheassumptionwasfalseforin-vesselfailureprobabilities.Therefore,non-conservativefailure probabilitieswereassignedtoPRAmodeltopeventsforcertainsce-narios.Thisapproachmayresultinanunderestimationoftheriskof

debris.Tuesday1 stMarch,2016:19:32,Page86of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONFailureoftheselectedpumpcon"guration(Case22)toupholdas-sumption2bcallsintoquestionthecombinationsoftheothercases usedtosimplifytheriskassessment.Therefore:

-Pleasedeterminewhetherassumption2bprovidesrealisticorboundingfailureprobabilitiesforeachpumpstatethatisas-signedanon-unityfailureprobability.

-PleaseprovideCDF,LERF,andusingrealisticorboundingfailureprobabilitiesforallpossiblepumpcon"gura-

tion.RemovedResponse,Pg.345

• CASAGrandetoPRAInterface7.Thelicenseesresponsetoquestion5oftheApril15,2014,RAI,con-tainsa"gureshowingthatthesmallestobservedbreaksizeleading todebris-inducedcoredamagewasapproximately17inches.Thisap-pearstocon"ictwiththeresponsetoquestion1,SuccessCriteria, whichstatedthat"thelargestbreaksizebelowwhichnofailuresre-latedtoeitherthesumporvesselperformancewererecordedduring theCASAGranderunswasaDEGBina5.189diameter(D)inch pipe."Pleaseclarifythesecontradictorystatements.RemovedResponse,Pg.345

• FidelitybetweenRELAPSimulationsandCASAGrande1.Volume6.2describestheRELAPsimulationsthatwereusedtode-terminewhethercorecoolingcouldbeaccomplishedwithpartialor completeblockage.Page123statesthatallthesafetysystemswere assumedtobeavailablethroughoutthetransient.Therefore,itwould appearthatTable2.5.39,CoreBlockageScenariosSummary,(Vol-ume6.2)wouldonlyapplytoscenarioswhereallECCSandCSpumps areavailable(i.e.,Case1).Theresponsetoquestion1,SuccessCri-teria,oftheApril15,2014,RAI,statesthatanalysesperformedin supportoftheLARincludedconsiderationofa6inchhotlegbreak withonlyonetrainofECCSavailable.[emphasisadded].Pleaseclar-ifyifthisreferstoananalysisperformedsubsequenttotheLAR.

Provideadditionaldetailsonthisoranyotheranalysesthatareused tojustifyapplyingtheresultsofTable2.5.39topumpstatesother thanCase1.Includeadescriptiononthequalityassuranceofthese analysesinrelationshiptoquestion1,SuccessCriteria.RoverDpartiallly requiredResponse,Pg.345

• State-of-KnowledgeCorrelation1.RG1.174Section2.5.2statesthatthestate-of-knowledgecorrelationshouldbeaccountedforunlessitcanbeshowntobeunimportant.In question5,UncertaintyAnalysis,oftheApril15,2014,RAI,the NRCrequestedthelicenseetoclarifywhythestate-of-knowledge correlationwasnotappliedtotheLOCAfrequenciesusedbythePRA andCASAGrande.STPsresponsestatedthat...dependenceofthe PRAandCASAGrandeontparametersoftheLOCAbreakTuesday1 stMarch,2016:19:32,Page87of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONfrequenciesisstsoasnottowarrantcorrelationbetweenthePRAandCASAGrande.Thisanswermaynotbeinaccuratebe-causethechoiceofLOCAfrequencypercentileboththeab-soluteLOCAfrequency(usedbythePRA)andtheshapeofLOCA frequencyversusbreaksizecurve(usedbyCASAGrande).There-fore,boththePRAandCASAGranderelyonthesameunderlying parameterandthestateofknowledgecorrelationapplies.Thisposi-tionwascommunicatedtothelicenseebytheAdvisoryCommittee onReactorSafeguards(ACRS)duringthemeetingonSeptember3, 2014(ADAMSAccessionNo.ML14266A510),andbytheNRC duringtheauditconductedfromSeptember15-17,2014.Pleasere-viseyouranalysisbycorrelatingtheLOCAfrequenciesusedbythe PRAandCASAGrande.PleasealsoprovideupdatedCDF,LERF, abasedonmeanvaluesresultingfromthepara-metricuncertaintycalculationthatproperlyconsidersthecorrelation betweentheinitiatingeventfrequenciesandthefailureprobabilities (sumpandin-vessel)fordebris-relatedevents.RemovedResponse,Pg.346

• SelectionofJohnsonParameters1.Intheresponsetoquestion4,UncertaintyAnalysis,oftheApril15,2014,RAI,STPNOCstatedthatitwasnotpossibletoapproximate theNUREG-1829meanfrequencieswithtselectionsofthe

parameter.NRCindependentanalysesindicateotherwise;forex-ample,thefollowingalternative"tsyieldsmeansthatarerelatively closetothosetabulatedinTable2.2.2oftheVolume3submittal.

PleaseevaluatethesensitivityoftheCDFandLERFondtse-lectionsofboundedJohnsondistribution"ts,suchasthealternative "tinthetablebelow.RemovedResponse,Pg.346Size(in)5 th1/yrMedian1/yrMean1/yr95 th0.50.0000680.000630.0018530.00714.625380.6712351.49E-0511.6255E-068.9E-050.0004080.00164.5513110.5680398.48E-080.26842723.69E-066.57E-050.0003010.001184.5943710.5683225.61E-080.21291432.1E-073.4E-061.59E-056.1E-056.0243480.5683772.31E-80.135431 66.3E-081.08E-065.16E-61.98E-056.1942460.564654.59E-090.062491 71.46E-083.04E-071.67E-066.34E-066.5299870.5413771.4E-110.052616 144.1E-101.2E-081.94E-075.8E-076.1425610.4226241.69E-100.024278 313.5E-111.2E-093.21E-088.1E-86.2071660.3891481.77E-110.011.4.2EMCB:MechanicalandCivilEngineeringBranch2.InaletterdatedDecember13,2013,thelicenseeexplainsthatthestrainerswereanalyzedfortwoloadcases.Case1correspondstothemaximum temperatureandalowdtialpressurewhichoccursearlyfollowinga loss-of-coolantaccident,whiledebrisloadingislow.Case2correspondsto amaximumtialpressure,whichoccurslaterwhendebrisloading isatamaximum,andcorrespondstoalowertemperature.Inbothcases theinteractionratiosaremaintainedbelow1.However,itisuncleartoTuesday1 stMarch,2016:19:32,Page88of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtheU.S.NuclearRegulatoryCommissionthatthesetwoloadcasesrepresentthemostlimitingloadingconditions,andboundallotherpossible temperatureandpressurecombinations.Therecouldbeacasewherethe tialpressureduetodebrisloadingincreasesatafasterratethan theyieldstressofthematerialincreasesduetothetemperaturedrop.ExplainthebasisforconcludingthatCase1andCase2aretheboundingpost-accidentloadingconditionsforthestrainers(i.e.,theyboundallother pressureandtemperaturecombinations).

RequiredResponse,Pg.3461.4.3ESGB:SteamGeneratorTubeIntegrityandChemicalEngi-neeringBranch

• Chemical23.DuringtheNRCauditinSeptember2014,representativesfromSTPNOCstatedthatthechemicalevaluationmodelwasbeing changedfromthechemicalbump-upfactormultiplierdiscussedin thelicenseessubmittaldatedNovember13,2013(ADAMSAccession No.ML13323A190),toanalternatechemicalmodelthatusesanad-ditivechemicalheadlossfactordeterminedfromthechemicalloading termL.Assumingthebump-upfactorapproachisnolongerbe-ingpursued,theNRChasreconsideredpreviouschemical relatedRAlsanddeterminedthatthefollowingApril15,2014,RAI questionsarenolongerrelevanttothenewchemicalmodel:1a-d,3á,

4,5,9,17,and18a-c.Pleasecon"rmthatthesunderstanding iscorrect.RemovedResponse,Pg.34624.TheNRChasreviewedtheoverviewofanalternatechemicalapproachcontainedinEnclosure1toAttachment5,Quan-ti"cationofChemicalHeadLossEpistemicUncertainty;Basisfor IncrementalChemicalHeadLossEpistemicUncertainty,contained inthelicenseesletterdatedJuly15,2014(ADAMSAccessionNo.

ML14202A045).Thisenclosureprovidesanoverviewofthealternate chemicalmethod.(a)PleaseprovideadetaileddescriptionofthischemicalheadlossmodelanditsapplicationtotheSTPplant-speci"cchemicalef-fectsanalysissuchthattheNRCcanperformathorough reviewandevaluation.(b)AspartofthedetaileddescriptionandbasedonCASAGranderealizations,pleaseprovideahistogramshowingchemicalhead loss(feet)onthex-axisandnumberofoccurrencesonthey-axisforthemedium-breakLOCA(MBLOCA)andlarge-break (LBLOCA)categories.Pleaseensurethebinselectionsallowthe NRCtodiscriminatetoutcomesthatresultinac-ceptableheadloss.(c)PleasediscusswhetherthechemicalheadlossdeterminedfromtheLmethodisindependentofthedebrisbedorinsomewaycorrelatedwiththedebrisbed.Tuesday1 stMarch,2016:19:32,Page89of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Pleasedescribeindetailhowthenewchemicalmodelwillac-countforuncertainties.Someexamplesofuncertaintiesinclude:

variabilityinchemicalheadlossbehavior(e.g.,anapproximate 40percentdinheadlossresultingfromachangetothe precipitateadditionsequenceinEnclosure1,Figure9),variabil-ityinheadlossacrosstdebrisbedsforthesametype andquantityofprecipitate,dincorrosion/leachingbe-haviorbetweentestmaterialsandplantmaterials,variabilityin temperatureorpHcomparedtotesting,otherpost-LOCAcon-ditions(e.g.,radiological)notpresentduringtesting.RemovedResponse,Pg.34725.TheNRChasseveralquestionsrelatedtoFigure14intheafore-mentionedEnclosure1toAttachment5.(a)GiventheheadlossresponsetochemicalprecipitateadditionshownearlierinFigures1and2,itseemsmoreappropriateto modelheadlossinanon-linearmanner.Pleasediscussanyplans tofurtherdevelopthemodel.(b)TheNRCsisoftheopinionthatthe4thBahndatapointplacementinthisplotisnotappropriategiventhatthetestloop wasshutdownatthispointsincethetestloopheadlosslimit hadbeenreached.Pleasediscussaplausiblerangeofheadloss forthistesthaditnotbeenstoppedandhowthatwould thechemicalheadlosscorrelation.(c)Withoutconsiderationofitem(b),theNRCcalculatedagreaterchemicalheadloss(CHL)value(approximately0.7feet) whenscalinga13feetofwaterresulttotheSTPstrainertest conditionsaccordingtoEquation2.Pleaseprovideacopyofthe calculationshowingthescaledvalueisapproximately0.4feet.(d)WhiletheNRCagreesthatcomparisonofchemicaltestingmayprovideinsight,therelationshipbetween"owand chemicalheadlossmaybemorecomplexthanasshownbyEqua-tion2.Pleaseprovideabasisforthisscalingequationordiscuss thelimitationsthatmayexistwhenextrapolatingdataovermore thananorderofmagnitudein"owrates.RemovedResponse,Pg.34726.Figure25inEnclosure1toAttachment5ofletterdatedJuly15,2014,showsnewaluminumreleaseequationsthatappeartobebased onexperimentsrunforSouthernNuclearOperatingCompany.(a)PleaseprovideacopyoftheReference17(CHLE-SNC-005BenchTest)ReportthatcontainsthisdatasothattheNRCmay understandhowthesetestswereperformed.(b)Con"rmthattheorangelineinFigure25representsthe1600seriestests.(c)ThealuminumreleasemodelappearstobepredictingthesamedataasinFigure24,whichwasusedtodevelopthemodel.Please clarifyifanyadditionaldatawasusedtodevelopthemodel.RemovedResponse,Pg.34727.AlimitedreleaseofaluminumduringchemicaltestingisoneofthekeyitemsSTPisrelyingonforconcludingSTPhasrela-Tuesday1 stMarch,2016:19:32,Page90of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtivelyminorchemicalInESGBquestion13.b.oftheApril15,2014,RAI,theNRCaskedifthetwopartsof hadbeentestedtocomparetheiraluminumrelease.Thelicensees responseprovidedscanningelectronmicroscopeimagesalongwith energydispersivespectroscopy(EDS)andx-rayphotoelectronspec-trometry(XPS)results.Giventhatthetwopartsofwereusedindttestconditions,thattheywerevisuallyobservedtohavettexture andappearance,andthattheTable1elementalcompositionsindicate potentiallysigni"cantinkeyelements(e.g.,Al,0,P),the NRCthinksitisimportanttoverifythatthecorrosionbehavior ofthetwopartsissimilar.Forexample,onewaytoverify similitudewouldbetorunadirectcomparisonofaluminumrelease inbenchtestsathigherpost-LOCAtemperaturestodetermineifthe aluminumreleasewasreasonablysimilar.Pleaseprovideacomparison ofthecorrosionbehaviorofthetwopartsofRemovedResponse,Pg.34728.Sincemultipletestssuggestaluminumcorrosionwillbeinhibitedbyphosphateafterarelativelyshorttimeintothepost-LOCAECCS missiontime,understandingthecorrosionbehaviorofaluminumat elevatedtemperaturesbecomesveryimportant.Recentaluminum corrosiontestingbyanotherlicensee(seeADAMSAccessionNo.

ML141848509,Slide18)showedthatfortheirplant-speci"ccondi-tions,signi"cantlylongertestdurationsat195degreesFahrenheit

(F)didnotreleaseanequivalentquantityofaluminumasshortertimeathighertemperatures.Pleasediscusstherelevanceofthesere-sultstotheSTPchemicalapproachforaluminumreleaseat highertemperatures.Pleaseincludeinthatdiscussiontherangeof postulatedplant-LOCAtemperaturepro"lesrelativetotheCHLE testMBLOCAandLBLOCApro"lesandifanyadjustmentsare neededtothealuminumreleaseratesattemperaturesgreaterthan

185F.RemovedResponse,Pg.34729.InSection2.1.1(ZincPhosphate)ofEnclosure1toAttachment5ofthelicenseesletterdatedJuly15,2014,thediscussionstatesthe following:WhenzinccorrosionmaterialswereincludedintheSTPrisk-informedtests,headlossresponsewasobservedduring theinitialhouroftesting;however,additionaltestsindicated thattheheadlossresponsetothezincproductwaslikelythe resultofinitialdissolutionofasurfacelayerandnotfrom transportofacontinuouslygeneratedzinccorrosionproduct H20).Therefore,theinitialzincproductre-leaseistreatedasaparticulatesourceandnotconsidereda zincchemicalproduct.SinceH20isunlikelyto transporttothestrainerand,giventhatOption1CHLis intendedtoproduceconservativeoroverestimatedCHLre-sponsetoidenti"edprecipitateloads,H20gen-erationisignoredintheCHLcorrelationdevelopment.Tuesday1 stMarch,2016:19:32,Page91of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONGiventhesigni"cantquantitiesofzincpresent,theNRC"ndsitwouldbeappropriateforachemicalmodeltoaccountforzinc.

Dissolutionofgalvanizedsteelorinorganiczinccoatingsmayoccur atthelowerpHbeforethetrisodiumphosphate(TSP)fully dissolvestoadjustthepHtoanalkalinevalue.Dissolvedzincwould thenbeavailabletoreactwiththephosphate.Inaddition,someper-centageofthegalvanizedsurfacescouldbesusceptibletohavingzinc corrosionproductknockedbywaterfallingfromthepipebreak, drains,etc.TheNRCrecognizesitmaybeappropriatetomodel zincproductsseparatelyfromamorphousaluminumhydroxidetype precipitatesifwarrantedbytheheadlossresponseacrossadebrisbed representativeofasumpstrainerbed.Pleaseprovidethequantityof zincthatisincludedintheparticulatesource,howthisamount ofzincheadlossandifanadditionalzincproductshouldbe includedinthemodel.RemovedResponse,Pg.34830.Figure21inEnclosure1toAttachment5ofthelicenseesletterdatedJuly15,2014,impliestheWCAP-16530releaserateequa-tionsarebeingincorporatedintoCASAGrandewhichisnotthe caseforaluminum.Pleaseclarifywhich,ifany,WCAP16530-NP-A,EvaluationofPost-AccidentChemicalinContainment SumpFluidstoSupportGSl-191,March2008(ADAMSAccession No.ML081150379),releaseequationswillbeusedwiththealternate chemicalheadlossmodelapproach.RemovedResponse,Pg.34831.Thechemicalheadlossisdeterminedbasedonchemicalprecipitateloadingperstrainer(gramspermetersquare(g/m 2)).Pleasedescribehowtheplant-speci"cincorporationofthismodelaccountsforthe greaterchemicalheadloadingforthecaseswherelessthanthree trainsoperatefollowingaLOCA.RemovedResponse,Pg.34832.ItisuncleartotheNRChowSTPNOCsresponsetoESGBquestion14.a.oftheApril15,2014,RAI,evaluatedtheradiation onprecipitates.Explainhowuncertaintiesfromtheradiation onprecipitateformationareconsideredintheSTPchemical analysis.RemovedResponse,Pg.34833.IntheresponsetoESGBquestion21oftheApril15,2014,RAI,themassof24poundsforaCRUDreleasefollowingaLOCAisbased upontheElectricPowerResearchInstitute(EPRI)Boron-Induced AnomalyestimatesoffueldepositsthatwouldaCRUD inducedpowershift(CIPS).Whilethismaybeanadequateprediction forCIPSsusceptibility,itdoesnotassessthetotalavailabletransient CRUDlayerintheprimarycoolantsystem.Thefuelsurfaceareais approximately30percentofavailablereactorcoolantsystem(RCS) surfacewithothersurfacessuchaspipingandSteamGeneratortub-ingmakingupmostoftheremainingsurfaceareas.TheEPRIPressurized-WaterReactor(PWR)PrimaryWaterChem-istryGuidelinesstate,inpart:Core"owtransientsshouldbeminimizedtominimizepar-ticulateentrainmentwhichwillincreasedoseratesandpar-Tuesday1 stMarch,2016:19:32,Page92of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONticulatecontaminationlevelsinlow"owregions.Wallshear,whichisapproximatelyproportionaltothesquareofthecoolant velocity,istheprimaryfactorpromotingparticulatereleases subsequenttoshutdown.Asmoothtransitiontoonepump operationisconsideredappropriatetoreduceshearandmin-imizeparticulatereleasesduringtheshutdowntransient.DuringareactortripfollowingaLOCAthereisnosmoothtransi-tionwithliquidandgaseous"owplussolidsentrainment.Thermal, hydraulicandchemicaltransientsareallpresent,simultaneously.One ofthemostsigni"cantchemicalchangesisthepresenceofbothhydro-genandoxygeninthewater"owingtothesumpaswellasbeingre-circulatedbackthroughthereactorcore.Thisuncontrolledchemistry conditionleadstobothreductiveandoxidativeprocessesoccurring simultaneouslyleadingtoparticulateformation.TheEPRIPWRPri-maryWaterChemistryGuidelines(Table3-5ofSection3.8)identi"es analysestobeperformedbyChemistryduringanormalshutdown, including"lterableandnon-"lterable:radioactivecorrosionproducts, elementalnickelandiron.Therefore,theChemistrydepartmentmay havethisinformationrelatedtonormalshutdownsandtransientshut-downs.Therefore,theNRCrequeststhatthelicenseedetermineifhis-toricalinformationisavailableconcerningcrudreleasefromnormal shutdownsandunplannedtripsandtore-evaluatethecrudrelease estimatebasedonanyadditionalinformation,includingreleasefrom allRCSsourcesduringaLOCA.

RequiredResponse,Pg.34834.Pleaseclarifythebetweenthe"beramountsshownintheTable2andFigure3inEnclosure1ofthelicenseesletterdatedJuly 15,2014.RemovedResponse,Pg.349

• Coatings8.Withrespecttoquestion1oftheApril15,2014,RAI,theresponsedoesnotseemconsistentwiththecurrentNRCspositionondebris characteristicsforunquali"edcoatings.Thetestingyoureferencedis notapplicabletounquali"edcoatings.Thispositionisdescribedin theNRCreviewguidanceavailableatADAMSAccessionNo.

ML080230462.Pleaseprovidearevisedanalysisfortheunquali"ed epoxycoatingsinquestion.RemovedResponse,Pg.3509.Thelicenseesresponseinquestion2oftheApril15,2014,RAI,statedthataZoneofIn"uence(ZOI)of4D(4Diameter)wasusedfor inorganiczinccoatings.Thispositionisinconsistentwiththecurrent NRCposition.BasedonthelatesttestdataavailabletheZOIfor inorganiczinccoatingsshouldbe1OD.Adescriptionofthisposition isavailableatADAMSAccessionNo.ML100960495.Pleaseprovide arevisedanalysisfortheZOIofinorganiczinccoatings.

RequiredResponse,Pg.35010.Withrespecttoquestion6oftheApril15,2014,RAI,thereductionscreditedfordebrisgeneratedbyunquali"edcoatingsinuppercon-tainmentisinconsistentwiththecurrentNRCposition.BothTuesday1 stMarch,2016:19:32,Page93of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthetreatmentoffailurepercentagesandfailuretimingarebasedonEPRItestingthatthehaspreviouslyissuedpositionson.

guidancefoundatADAMSAccessionNo.ML080230462describesthe spositionwithrespecttothistesting.InadditiontheNRC concernsregardingthefailuretimingbeingbasedon"lterdata(as describedintheoriginalquestions6band6c)arenotadequatelyad-dressedbyyourresponses.Pleaseprovidearevisedanalysisforthe unquali"edcoatingsinuppercontainment.

RequiredResponse,Pg.3501.4.4SCVB:ContainmentandVentilationBranch10.

Background:

Theresponsetoquestion3.aoftheApril15,2014,RAI,doesnotappeartoprovideadequatejusti"cationfornotrevising theUpdatedFinalSafetyAnalysisReport(UFSAR)descriptionof thecontainmentheatremovalanalysis.Theresponsetoquestion3.c referstoaproposedUFSARdescriptionoftheriskassessmentgiven inEnclosure3,Attachment2ofthelicenseesletterdatedNovember 13,2013,whichdoesnotprovidearevisedlicensingbasisdescription ofthecontainmentheatremovalanalysis.Thelicenseesresponsetoquestion4.aoftheApril15,2014,RAI,doesnotprovideadequatejusti"cationfornotrevisingtheUFSAR descriptionofthe"ssionproductremovalanalysis.Theresponseto question4coftheApril15,2014,RAI,referstoaproposedUFSAR descriptionoftheriskassessmentgiveninEnclosure3,Attachment2 ofthelicenseesletterdatedNovember13,2013,whichdoesnotpro-videarevisedlicensingbasisdescriptionoftherevised"ssionproduct removalanalysis.Pleaserefertothefollowingexcerpttakenfromthelicenseesresponsetoquestion3.boftheApril15,2014,RAI:AsdescribedintheLAR,theproposedexemptionsfromGen-eralDesignCriteria(GDC)-35,EmergencyCoreCooling, GDC-38,ContainmentHeatRemoval,andGDC-41,"Con-tainmentAtmosphereCleanup"areforapprovalofarisk-informedapproachforaddressingGSl-191andrespondingto GenericLetter(GL)2004-02forSTPUnits1and2asthe pilotplantsforotherlicenseespursuingasimilarapproach.

Asfurtherdescribed,STPNOCseeksNRCapprovalbased onadeterminationthattheriskinformedapproachandthe riskassociatedwiththepostulatedfailuremechanismsdueto GSl-191concernsmeetstheguidance,keyprinciplesforrisk-informeddecisionmaking,andtheacceptanceguidelinesin RG1.174.STPisnotproposingtoapplytherisk-informed approachtorevisethelicensingbasisforcontainmentdesign describedintheUFSAR.Theproposedriskassessmenteval-uatesaspectrumofLossofCoolantAccident(LOCA)sce-nariostoquantifytheamountofdebrisofvarioustypesthat mightbegeneratedandtransportedtotheemergencysumps, andhowthatdebrismightctavailableNPSH[netpositiveTuesday1 stMarch,2016:19:32,Page94of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsuctionhead]forEmergencyCoreCoolingSystem(ECCS)andContainmentSpraySystem(CSS)pumpstakingsuction fromthesumpsintherecirculationmode.Italsoevaluates potentialtransportofdebristothereactorcore.Itcalculates failureprobabilitiesthatarefedtotheSTPPRA.

Concern:Theagreesthatthecurrentlylicenseddesignandcon-"gurationoftheCSSandECCSasdescribedintheUFSARwillnot beimpactedbytherisk-informedresolutiontoGSl-191exceptforthe changeinthesumpstrainerdesign.However,theNRCisnot inagreementthattheUFSARdescriptionofthelicensingbasiscon-tainmentheatremovalanalysis.whichusesCSS;thelicensingbasis containment"ssionproductremovalanalysis.whichalsousesCSS; andthelicensingbasis10CFR50.46analysis.whichusesECCS, willnotbeimpactedbytherisk-informedresolutiontoGSl-191.For breaksthatproducelessornodebris,thelicensingbasisanalysis shouldbebasedonthedeterministicapproachwithouttakingex-emptionfromGDCs35,38,and41.Forbreaksthatproducelarge amountofdebrisandwithouttakingexemptionsfromtheGDCs(for exampleexemptionfromassumingsinglefailure)itisnotpossible tomeettheacceptancecriteriaforpeakcladdingtemperatureand containmentheatand"ssionproductremoval,therisk-informedap-proachmaybeusedandexemptionfromtheGDCsmayberequested forthesespeci"cbreaksonly.TheNRChasdevelopedthe"owchartshowninFigure1(onpage19ofthisRAI)forde"ningtheLOCAcontainmentNPSHlicens-ingbasisanalysis(whichisthemostsigni"cantpartofcontainment heatremovalanalysis)fordeterministicandrisk-basedGSl-191res-olution.Thesuggeststhelicenseetodevelopsimilar"owcharts de"ningthedeterministicandrisk-based"ssionproductremovaland ECCSlicensingbasisanalysis.

Question:RG1.174requiresthatthelicenseeshouldidentifythoseaspectsoftheplantslicensingbasisthatmaybebythe proposedchange,includingbutnotlimitedtorulesandregulations, UFSAR,technicalspeci"cations,licensingconditions,andlicensing commitments.NUREG-0800,StandardReviewPlanfortheReview ofSafetyAnalysisReportsforNuclearPowerPlants,(SRP)Chap-ter19.2,ReviewofRiskInformationUsedtoSupportPermanent Plant-speci"cChangestotheLicensingBasis:GeneralGuidance, Section111.1alsorequiresthatthechangesintheplantlicensingba-sisshouldbeappropriatelyre"ectedinlicensingdocumentssuchas technicalspeci"cation(TS),licenseconditions(LCs),andUFSAR.

Therefore,thecurrentlicensingbasisforthecontainmentheatre-movaldescribedinUFSARChapters6and15mustberevisedby includingthedescriptionforthebreaksforwhichpartialorcomplete exemptionfromGDCs35,38,and41isrequested.(a)ProvideUFSARrevisionsofChapters6and15forthedescriptionofrevisedlicensingbasisanalysisofthecontainmentheatremovalTuesday1 stMarch,2016:19:32,Page95of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONforthebreaksforwhichexemptionfromGDC-38isrequested.(b)ProvideUFSARrevisionsofChapter6forthedescriptionofrevisedlicensingbasisoftheanalysisofthecontainmentspray system-iodineremovalforthebreaksforwhichexemptionfrom GDC-41isrequested.(c)ProvideUFSARrevisionofSection6.3forthedescriptionofrevisedlicensingbasisanalysisoftheECCSforthebreaksfor whichexemptionfromGDC-35isrequested.

RequiredResponse,Pg.35011.Pleasenotethattheuseofrisk-basedapproachforresolutionofGSl-191requiresachangeinthelicensingbasisfortheCSSoperatingin thepresenceofdebris.RG1.174describesanacceptableapproachfor assessingthenatureandimpactofproposedlicensingbasischanges.

ThisRGrequiresthatthelicenseeshouldidentifyallSSCs,proce-dures,andactivitiesthatarecoveredbythelicensingbasischange beingevaluated.Theresponsetoquestion1.aoftheApril15,2014,RAI,statesthattheCSSistheonlysystemforwhichtheexemptionfromGDC-38is requested.NotethattheCSShasassociatedsupportingsystemssuch asthesafety-relatedelectrical,EmergencyDieselGenerator(EDG),

instrumentationandcontrol(l&C),andcoolingwatersystems.There-fore,asrequiredbyRG1.174,pleaseidentifyalltheassociatedSSCs, proceduresandactivitiesthatsupporttheoperationoftheCSSfor containmentheatremovalinthepresenceofdebris.

RequiredResponse,Pg.35312.Theresponsetoquestion1.boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-38willnotbemet.ThekeyGDC-38requirementstobemetfortheCSSsystemdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Performthesafetyfunctionofcontainmentheatremoval,andrapidlyreducethecontainmentpressureandtemperatureand maintainthematacceptablylowlevel.

RequiredResponse,Pg.353(2)Safetyfunction(1)shallbeperformed follow ingany LOCA.RequiredResponse,Pg.354(3)Safetyfunction(1)shallbeperformed in the pres ence or ab sence of Loss ofsitePower(LOOP).Response,Pg.354(4)Safetyfunction(1)shallbeperformed in the pres ence of aworst sin gle fail ure.RequiredResponse,Pg.354Notethatrequirement(2)coversallpostulatedLOCAsofanybreaksize,includingthemostlimitingfromdebrisgeneration,containment peakpressure,andcontainmentpeaktemperaturestandpoint.Pleaseprovidethefollowinginformation:(a)IsfullexemptionfromtheGDC-38requirements(2),(3),and(4)requested?Ifso,irrespectiveofthebreaksize,breaklocation,or quantityofdebrisgeneration,allCSStrainsalongwiththeir supportingsystemmaybeused.Pleaseprovidejusti"cationfor theproposalofafullexemptionfromtheserequirements.

RequiredResponse,Pg.354Tuesday1 stMarch,2016:19:32,Page96of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)IsapartialexemptionfromGDC-38requirement(2)requested(i.e.,forspeci"cLOCAsonlyandfullexemptionfromrequire-ments(3)and(4))?Ifso,specifytheLOCAsintermsoflocation, breaksize,anddebrisgenerationrateforwhichtheexemptionis requestedfrommeetingrequirement#(3)and#(4),andprovide justi"cationfortheexemptionrequest.

RequiredResponse,Pg.35413.Theresponsetoquestion2.aoftheApril15,2014,RAI,statesthattheCSSistheonlysystemforwhichtheexemptionfromGDC-41is requested.NotethattheCSSalsohasassociatedsupportingsystems towhichGDC-41mayapply.Pleaselistalltheassociatedsystems thatsupporttheoperationoftheCSS;suchasthesafety-relatedelec-trical,EOG,l&C,andcoolingwatersystems.Thereforeasrequired byRG1.174,pleaseidentifyalltheassociatedSSCs,proceduresandactivitiesthatsupporttheoperationoftheCSSfor"ssionproduct removalinthepresenceofdebris.

RequiredResponse,Pg.35514.Theresponsetoquestion2.boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-41willnotbemet.ThekeyGDC-41requirementstobemetfortheCSSsystemdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Pleaselistsystemsrequiredtoperformthesafetyfunctionofcontrolling"ssionproducts,hydrogen,oxygen,andothersub-stancesthatmaybereleasedintothereactorcontainmentto reduce,consistentwiththefunctioningofotherassociatedsys-tems,theconcentrationandqualityof"ssionproductsreleased totheenvironmentandtocontroltheconcentrationofhydrogen andoxygenandothersubstancesinthecontainmentatmosphere toassurethatcontainmentintegrityismaintained.

RequiredResponse,Pg.355(2)Safetyfunction(1)shallbeperformedfollowingallpostulatedaccidents.

RequiredResponse,Pg.355(3)Safetyfunction(1)shallbeperformedbyprovidingsuitablere-dundancyincomponentsandfeatures,suitableinterconnections, leakdetectionandisolation,andcontainmentcapabilities.

RequiredResponse,Pg.355(4)Safetyfunction(1)shallbeperformedinthepresenceorabsenceofLOOP.RequiredResponse,Pg.355(5)Safetyfunction(1)shallbeperformedinthepresenceofaworstsinglefailure.

RequiredResponse,Pg.355Pleaseprovidethefollowinginformation:(a)IsfullexemptionfromtheGDC-41requirements(2),(3),(4),and(5)requested?Ifso,thanirrespectiveofthebreak size,breaklocation,orquantityofdebrisgeneration,allCSS trainsalongwiththeirsupportingsystemmaybeused.Please providejusti"cationfortheproposalofafullexemptionfrom theserequirements.

RequiredResponse,Pg.355(b)IsapartialexemptionfromGDC-41requirement(2)requested(i.e.,forspeci"cLOCAsonly,andfullexemptionfromre-quirements(3),(4),and(5))?Ifso,specifytheLOCAsinTuesday1 stMarch,2016:19:32,Page97of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtermsoflocation,breaksize,anddebrisgenerationrateforwhichtheexemptionisrequestedfrommeetingrequirements (3),(4),and(5),andprovidejusti"cationfortheexemption

request.RequiredResponse,Pg.35615.Theresponsetoquestion9.aoftheApril15,2014,RAI,statesthattheECCSistheonlysystemforwhichtheexemptionfromGDC-35isrequested.PleasenotethattheECCSwhosesubsystemsare HighHeadSafetyInjection(HHSI)andtheLowHeadSafetyInjec-tion(LHSI)systemsarenottheonlyonesforwhichtheproposed exemptiontoGDC-35wouldapply.Listallofthesupportingsystem thatsupporttheoperationoftheHHSIandLHSIsubsystems;for examplethesafety-relatedelectrical,EDG,l&C,andcoolingwater systems.ThereforeasrequiredbyRG1.174,pleaseidentifyallthe associatedSSCs,proceduresandactivitiesthatsupporttheoperation oftheHHSIandLHSIsystemsinthepresenceofdebris.

RequiredResponse,Pg.35616.Theresponsetoquestion9boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-35willnotbemet.ThekeyGDC-35requirementstobemetfortheECCSdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Performthesafetyfunctionoftransferringheatfromreactorcoreataratesuchthat(a)fuelandcladdamagethatcouldinterfere withcontinuedeecorecoolingispreventedand(b)clad metal-waterreactorislimitedtonegligibleamounts.

RequiredResponse,Pg.356(2)Safetyfunction(1)shallbeperformed follow ingany LOCA.RequiredResponse,Pg.356(3)Safetyfunction(1)shallbeperformedbyprovidingsuitablere-dundancyincomponentsandfeatures,suitableinterconnections, leakdetectionandisolation,andcontainmentcapabilities.

RequiredResponse,Pg.356(4)Safetyfunction(1)shallbeperformed in the pres ence or ab sence ofLOOP.RequiredResponse,Pg.356(5)Safetyfunction(1)shallbeperformed in the pres ence of aworst sin gle fail ure.RequiredResponse,Pg.357Notethatrequirement(2)covers allpos tu lated LOCAsofanybreaksize,includingthemostlimitingfromdebrisgenerationor peakcladtemperaturestandpoint.Pleaseprovidethefollowing

information:(a)IsfullexemptionfromtheGDC-35requirements(2),(3),(4),and(5)requested?Ifso,irrespectiveofthebreaksize, breaklocation,orquantityofdebrisgeneration,allECCS trainsalongwiththeirsupportingsystemmaybeusedfor performingsafetyfunction(1).Pleaseprovidejusti"cationforrequestingafullexemptionfromtheserequirements.

RequiredResponse,Pg.357(b)IsapartialexemptionfromGDC-35requirement(2)requested(i.e.,forspeci"cLOCAsonlyandfullexemptionfromrequire-ments(3),(4),and(5))?Ifso,specifytheLOCAsinterms oflocation,breaksize,anddebrisgenerationrateforwhich theexemptionisrequestedfrommeetingrequirement#(3),Tuesday1 stMarch,2016:19:32,Page98of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION#(4),and#(5),andprovidejusti"cationfortheexemption request.RequiredResponse,Pg.35717.Inquestion7oftheApril15,2014,RAI,theNRCrequestedthelicenseetoprovidetheequivalentofUFSARSection6.2.1.5,which shoulddescribethelicensingbasisoftheminimumcontainmentpres-sureanalysisforperformancecapabilityofECCSinthepresenceof debrisfortherisk-basedanalysis.SuccessfulfunctioningoftheLHSI, HHSIsystemsandtheCSSinthepresenceofdebrisrequiresex-emptionfromGDC-35andGDC-38.Therefore,inthepresenceof debrisduringLOCAs,thedescriptionoftheminimumcontainment pressureanalysisforperformancecapabilityshouldbedtfrom whatisdescribedintheUFSARSection6.2.1.5.Thelicenseesre-sponsetoquestion7didnotdescribetheproposedcontainmentanal-ysis,includingassumptionsandinputs,performedforthecalculation ofminimumcontainmentpressureinputfortheECCSanalysisthat calculatesthepeakcladdingtemperatureforrisk-informedGSl-191.

Pleasejustifythattheinputsandassumptionsareconservativefor thepurpose.

RequiredResponse,Pg.35718.Pleaseprovidethefollowingadditionalinformationwithrespecttoyourresponsetoquestion3.boftheApril15,2014,RAI:(a)Refertothetableonpage9ofAttachment3tothelicenseeslet-terdatedJune25,2014(ADAMSAccessionNo.ML14178A481),

ofmajorqualitativedforthesubjectSumpPoolTreat-ment,pleaseexplainwhatismeantby:Nodecayheatadded.

MassandenergysubtractedfromthepoolbasedonRELAP-3D instructions.(b)Refertothetablereferencedinitema)forthesubjectPipebreakmass/energysource,pleaseexplainwhatismeantby:

CommunicatedfromRELAP5-3Dviacouplinginterfaceasprob-lemtimeprogresses.ThesourceissplitbyMELCORintopart liquidwater,partsteam,andpartfog.(c)RefertothetableundertheheadingSummaryComparisonofMainParameterValues,onpage10ofAttachment3tothe licenseesletterdatedJune25,2014,pleaseprovidethebasisfor selectingtheRELAP-3D/MELCORvaluesoftheparametersin thetablebelowandhowaretheydetermined:RELAP-3D/MELCORVALUEInitialatmospheretemperature119.93FInitialcontainmentpressure14.94psiaInitialrelativehumidity,partialpressureofwatervapor70%/1,184psiaInitialRWSTtemperature85FSprayactuationtimes15sdelayaftersetpoint,linearramptofull"owFancooleractuationtimes15sdelayaftersetpointTuesday1 stMarch,2016:19:32,Page99of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Refertothetablereferencedinitemc)fortheCONTEMPTandRELAP-3D/MELCORanalysis,pleaseprovidethebasisfor usingdtvaluesof(1)thermalconductivityofconcrete,(2) thermalconductivityofstainlesssteel,(3)speci"cheatcapacity ofconcrete,(4)speci"cheatcapacityofstainlesssteel,and(5) densityofstainlesssteel.

RequiredResponse,Pg.357Tuesday1 stMarch,2016:19:32,Page100of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.4.5SNPB:NuclearPerformanceandCodeReviewBranchTheNRChasreviewedtheSTPRELAP5-3Dwiththe1-Dcoreanal-yses,entitledCoreBlockageThermal-HydraulicAnalysis.TheNRCrecognizesthattheseanalyseshavetheobjectiveofdemon-stratingthatundertheblockedcoreinletcases,twatercanmatch bandmaintaincoolabilityandtheRELAP5analyseshaveshownthe conditionsforwhichthisistrue.However,thealsorecognizesthat whiletwateradditiontothecoreistobejusti"edtomatch/exceed bprecipitationofboricacidinthecorewithvariousblockagesalso needstobeaddressed.Assuch,theanalysesonlyaddressthe"rstcritical issueforlong-termcooling,butwouldrequireanevaluationofprecipitation tobeabletostatethatlong-termcoolinghasbeendemonstrated.With-outtheprecipitationevaluation,long-termcoolingcannotbejusti"ed.It isnotedthattheRELAP5-3Dcodetrackstheboronsoluteconcentration, howeveritdoesnotincludeboricacidbuild-upontheliquiddensityand thestaticheadterminthemomentumequation.Assuch,"owratesand thermalhydraulicbehaviormaybeofconcern.Also,transportproperties withincreasedboricacidconcentrationsisalsoomittedinRELAP5-3D.

TheNRCrequeststhefollowingadditionalinformation:1.Forthesmall2-inchcoldlegbreakofTable2,whilewater"llsthesteamgeneratorcoldsidesspillingovertothehotsideandre"lling thecoretokeepitcooled,thequestionofprecipitationcouldbean issuethatrepresentsfailureforthiscase.Thatis,withthecoreto-tallyblockedthereisnomeansof"ushingtheboricacidbuild-up inthecorethatbeginsuponinitiationofboiling.Ifitassumedno watercanpassthroughtheblockedregionfromcoldsideinjection thenswitchingtohotsideinjectionshouldnot"ushtheboricacid build-upfromthecore.Itwouldbeinstructivetoperformaprecipi-tationcalculationtoshowthetimingforprecipitationoncethecore beginstoboil.SincetheRCSpressureisfairlyhightheprecipitation limitwillbelikewisehigher,butitisnotclearthattheprecipita-tionlimitwillnotbereached.Itappearsthatwiththecoretotally blocked,precipitationcannotbeavoided.Pleaseexplainandprovide anevaluationofprecipitationtimingforthiscase.

RequiredResponse,Pg.3572.Thecaseswithoneassemblyunblocked(centerandperiphery)pre-sentedinFigure32showsadequatewaterentersthecoretomatch bHowever,asboricacidbuildsupinthecore,thedensityin-creasesdegradingthe"owintothecore.Giventhatthedowncomer levelis"xedduetothebreak,"owwouldbeexpectedtodecrease asthedensityinthecoreincreases.Assuch,calculationofthepre-cipitationtimingandmixinginthecoreneedstobeevaluated.Since thereisonlyoneunblockedassemblybottomlocation,itisnotobvi-ousthattheswitchtosimultaneousinjectioncan"ushtheboricacid fromthecorethatbuilds-uppriortotheswitchtoprecludeprecip-itation.Furthermorewithonlytheoneopenassemblyinletpathto thecoreregions,locationsneartheperipherycantrapboricacidandTuesday1 stMarch,2016:19:32,Page101of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcauselocalbuild-upofconcentrationthatmaynotbe"ushedoutwithhotsideinjection.Itisnotclearthatprecipitationcanbeprecluded fortheseblockedcases.Pleaseprovideadetailedexplanation.

RequiredResponse,Pg.3583.ThecaseinFigure32withthebypassfreeshowsadequatewaterentersthecoreforcooling.Pleaseidentifytheelevationsabovethe bottomofthecorewherethesebypasspathsarelocated.Ifthe"rst bypassislocatedabovethebottomelevationofthecore,thisre-gionofthecorebelowthe"rstbypasspathwilltrapboricacidand build-uptopotentiallyreachprecipitation.Itisnotclearhowthe downwardandthenupward"owcan"ushtheboricacidfromthis lowerisolatedregion.Ifthebypassislocatedatthecorebottomel-evationitisstillnotclearifsimultaneousinjectioncanarrestthe build-upofboricacidand"ushthecorethroughthebypassregion.

Pleaseexplainhowprecipitationispreventedanddemonstratethat RELAP5-3Dcanpredictthecorrect"owsto"ushthecoreunder theseunusual"owpathcon"gurations.SincetheRELAP5-3Dcode doesnotincludethedensityincreaseswithboricacidconcentration, pleaseexplainanddemonstratethatthe"owandmixingbehavior inthecorecanbecorrectlycalculated.Whatvalidationcalculations havebeenperformedtoshowthattheomissioninthemomentum equationdonotprovideexcessive"owandmixingbehavior,noting thatthetransportpropertiesarealsoomittedinthecode.

RequiredResponse,Pg.3584.PleasedescribehowtheadvectionterminRELAP5-3Disnumeri-callyexpressedanddemonstratethatnumericaldoesnot produceerroneousorexcessive"owbehaviorthatcouldchangethe conclusionsofthisanalysis.Sinceadvectionanddcanplay keyrolesinthecalculatedliquidandsteamvelocitiesinthe core,pleasedemonstratethatRELAP5-3Dcanproperlymodelthese Itmaybeadvantageoustosolvethetransportequationwith advectionanddina1-Dpipeand3-Dvolumeusingthesame numericalapproximationinRELAP5-3Dfortheadvectionandthe secondorderviscousdterms.Pleaseshowthatastepfunction densitywaveorconcentrationwavemovingdownthepipedoesnot fromnumericalcharacteristicofthe1-Dupwinddif-ferencingschemethathasbeenemployedinRELAP5codeversions.

RequiredResponse,Pg.3585.Thereviewindicatesthattheswitchtosimultaneousinjectionforsomeofthecasesoccursatttimesforthevariousbreaks evaluated.Forexample,Figure8showstheswitchtimeatabout 32,000secondsforthe2-inchhotlegbreakwhileFigure27shows about22,000secondsfortheswitchforthedoubleendedguillotine hotlegbreak.TypicallytheswitchtimeisanEmergencyOperating Procedureactionandoccursatonetimethatistlyearly enoughthatassuresallbreaksizesare"ushedpriortoreachingthe precipitationlimitforthelimitingcase.Theseshouldhave noimpactontheanalysisconclusionsbutpleaseexplainthebasisand verifythattheuseofdttiminghasnoimpactontheresultsand conclusionsanddoesnotimpacttheEmergencyOperatingProcedureTuesday1 stMarch,2016:19:32,Page102of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONguidancefortheoperators.RemovedResponse,Pg.3581.4.6SSIB:SafetyIssueResolutionBrancha.Round2RAIquestionnumbersbeginwiththenextsequentialnumberfromtheApril15,2014,RAI(Round1)forthissection.b.Follow-upquestionsfromtheSTPNOCresponsestotheRound1RAIquestionsreferbacktotheRound1RAInumberfromthissection unlessotherwisespeci"ed.43.Inquestion2oftheApril15,2014,RAI,thelicenseestatedthatthevaluesforsizedistributionsforthe"brousinsulationaredocu-mentedinReference46.Reference46wasnotincludedinthesubmit-tal.Pleaseprovideasummaryoftherelevantsizeinformationfrom Reference46intheformofatableincludingthesizedistributions withinthepostulatedZOls.

RequiredResponse,Pg.35844.Inquestion4oftheApril15,2014,RAI,thatNRCsreviewindicatesthatitislikelythattheSTPmethodologydiscussedinthe responsemaybeacceptableandmayprovideconservativetransport resultswhenconsideredwithintheprobabilisticframework.However, lowdensity"berglass(LDFG)congestionmaynotbethemetricthat dominatesthelikelihoodofdebrisreachingthestrainerbasedon breaklocation.Althoughtheuseofthesteamgeneratorcompart-menttransportfractionmaybemoderatelyconservativeasclaimed, theNRCwasunabletoverifythisassumption.Itwasalsonot cleartothethatthemeasureof"bercongestionwithinspecif-icallyde"nedvolumesincontainmentprovidethemostimportant measureofdebrisamountsthatmaybegeneratedortheprobability thatdebriswouldbegeneratedwithinthosevolumes.Ifonelocation iscongested,butthe"brousdebrisinthatareacannotbedamagedby abreakitisnotrelevant.Pleaseverifythatthemethodologyresults inoverallrealisticorconservativetransportfractionsconsideringthe possiblebreaklocationsandtheLDFGcongestion.

RequiredResponse,Pg.35945.Forquestion6.a.oftheApril15,2014,RAI,theNRC"ndsthatthelicenseedidnotprovideanadequateresponsetothequestion.

TheDrywellDebrisTransportStudy(DDTS)statesthatifgratings donotcoveranentiretransportpaththattheymaynotbeasef-fectiveindebriscaptureasnotedinthetestmetrics.Simplyusinga ratioofopenareatototalareamaynotprovidearealisticorcon-servativeestimateofdebriscapture.Thegratedareaislikelytohave higherresistanceto"owthatwillincreaseasitcollectsdebris.Debris isgenerallyassumedtobehomogeneouslydistributedthroughoutthe blowdown"ow.Iflessvolumeofblowdownpassesthroughthegrating dueto"owresistance,lessdebrisisavailabletopassthroughorcollect onthegrating.TheNuclearEnergyInstitute(NEI)baselineguidance assumesthatsmall"nesaredebristhatwillpassthroughgratings, sonoholdupofsmallor"ne"brousmaterialisassumedusingbase-linemethodology.Thebaselinefurtherassumessmall"nestobetheTuesday1 stMarch,2016:19:32,Page103of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONbasicconstituentofthedebrisfortransportpurposes.Therewerenore"nementsregardingcreditinggratingstoreducetransportfoundin eitherNEI04-07ortheNRCSEon04-07.Therefore,thelicensee shouldjustifytheassumptionthattheamountofdebriscapturedby gratingsinpathwaysthatarenotfullycoveredcanbeestimatedus-ingasimpleratiooftheopenareatototalarea.Pleaseprovidea justi"cationthatthedebriscapturemetricsusedintheevaluation arerealisticconsideringtheissueidenti"edabove.

RequiredResponse,Pg.36446.Thelicenseesresponsetoquestion7.b.oftheApril15,2014,RAI,statedthatthesigni"cantlylongerwashdownperiodsatSTP,com-paredtothelengthoftheDDTSwashdowntestsareinconsequential totheSTPevaluation.Theconclusionisbasedonaportionofthe NEIguidancedocument,NEI04-07,thatfoundtheerosionof"brous debrisbycontainmentsprayislessthanonepercent.TheRAIaimed attheerosionof"brousdebrisbycontainmentspray,butrequested forclari"cationifthewashdownof"brousdebristhroughgratings wouldincreaseabovethatfoundduringtheDDTSandifthewash-downtimeissigni"cantlyincreased?TheNRCisspeci"cally interestedinthesmall"berwashdowntransportfractionsprovided inTable2.2.23ofVolume3ofthelicenseessubmittaldatedNovem-ber13,2014.Thesevaluesarecurrentlylistedas7-19percentwashed downintheannulusand21-27percentwasheddowninsidethesec-ondaryshieldwall.Thesedonotappeartobe"brouserosionval-ues.Pleaseprovidejusti"cationthatthewashdownvaluesfroma 30-minutetestareapplicabletotheSTPconditionconsideringthe clari"cationprovided.

RequiredResponse,Pg.36747.Inquestion14oftheApril15,2014,RAI,theNRCrequestedthebasisfortheuseof1/16inchasthevaluebelowwhicha"ltering bedisassumednottooccur.Thelicenseesresponsetothequestion isbasedonNRCsacceptanceoftheheadlosscorrelationand asensitivitystudythatshowednochangeinCDFifthecriterion isreducedtozeroinches.Becauseneitherhasbeenacceptedatthis time,theacceptabilityoftheresponsetoRAI14isindeterminate.

Additionally,theuseofa1/16-inchcriterionbelowwhichchemical cannotoccurisnotsupportedbysomeindustryteststhathad 1/16inchof"berorlessadded.Sometestshadmeasurableincreases inheadlosswithlessthan1/16-inchtheoretical"beronthestrainer afterchemicalswereaddedtotheloop.TheNRCagreesthatitis unlikelythataheadlossgreatenoughtoresultinstrainerfailurewill occurwithsuchalow"berload.However,thepotentialforthehead losstoresultin"ashingoradditionaldeaerationwasnotaddressed bythelicensee.Thesensitivitystudywasalsoconductedbeforecor-rectionstopoollevelandcleanstrainerheadloss(CSHL)valueswere implemented.Asstatedabove,theNRChasnotacceptedthe headlosscorrelationusedtoperformthesensitivitystudy.Theli-censeeisrequestedtoproviderevisedresponsetoRAI14considering theinformationdiscussedabove.RemovedResponse,Pg.368Tuesday1 stMarch,2016:19:32,Page104of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION48.Questions15,16,17,18,21,and22oftheApril15,2014,RAI,re-questedadditionalinformationregardingthelicenseesuseofacor-relationtocalculatedebrisheadloss.TheNRChasestablished apositionthatcorrelationsmaynotbeusedtocalculateheadloss unlessthecorrelationisvalidated,underplant-speci"cconditions,for therangeofconditionstowhichtheresultswillbeapplied.Thisposi-tionwasdiscussedwiththelicenseebeforetheformalsubmittal.The NRCdoesnotconsidertheresponsestobeadequatesincethe licenseesuseofcorrelationswerenotvalidatedunderplant-speci"c conditions.Thelicenseeisrequestedtoprovidearevisedresponse consistentwiththeNRCposition.RemovedResponse,Pg.36849.Thelicenseesresponsetoquestion27oftheApril15,2014,RAI,statedthattheuseof0.220ftastheCSHLvaluewasanerror.The licenseeperformedsensitivitystudiestodeterminetheofusingthecorrectvalueof1.952ftonoverallCDF.Thelicenseestatedthat thechangeinCDFwouldbeabout18percentwhenthecorrectvalue isused.ThelicenseealsostatedthatamoreaccurateCSHLvalue wouldbeused.Doesitmeanthat1.952ftisthemoreaccurate valueofCSHL?Ifnot,pleaseprovidethe"moreaccurate"valueof CSHLthatwillbeusedinfuturecalculations.

RequiredResponse,Pg.36950.Thelicenseesresponsetoquestion28oftheApril15,2014,RAI,statedthattheuseofaheadlosscorrelationisessentialtotherisk-informedmethodbecauseitprovidesunderstandingofsubtleinter-actionsbetweenvariableparametersconsideredintheanalysis.How-ever,theneedtoapplya5Xsafetyfactortobounduncertainties inthecorrelationindicatesthatcon"denceinthemethodisrela-tivelylowandthatevaluationofinteractionsbetweentheparameters maybesigni"cantlyskewed.Theserelationshipsmaybefurthermis-characterizedbyresortingtoalimitingpackingfactorforthedebris bed.Theresponseprovidesasensitivitystudyforsafetyfactorvalues aroundthe5Xvalueusedintheevaluation.However,theresponse doesnotprovideabasisforthevaluesusedinthestudy.TheNRC believesthatbecausethereareuncertaintiesinmanyaspectsof themodelandthatmanyofthesearesigni"cant,thatthe5Xmul-tipliermaynotenvelopetheseuncertainties.TheRAIresponsedoes notappeartoaddresstwosigni"cantissues,theuncertaintycausedby non-homogeneousbedsandthelackoftestingtovalidatethemodel forplant-speci"cconditionsthatleadtomodeluncertainty.Other uncertaintiesinherenttotheuseofcorrelationsforheadlossshould alsobeaddressedincludingstatisticaluncertaintiesarisingfromthe useoftestdata,uncertaintiesarisingfromtheuseofthecorrela-tion,anduncertaintiesintroducedbyassumingthattestconditions arerepresentativeoftheplant.Pleaseprovideanevaluationofhow theindividualuncertaintieswithinthemodelareaccountedforand provideanestimateofthetotaluncertaintycreatedbyuseofthe model.RemovedResponse,Pg.36951.Thelicenseesresponsetoquestion31oftheApril15,2014,RAI,Tuesday1 stMarch,2016:19:32,Page105of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONdescribedacalculationthatevaluatesthepotentialforthecollec-tionofgasbubblesintheSTPstrainer.ThelicenseecitesReference 56ofVolume3,TDl-6005-07,VortexAirIngestionandVoidFrac-tionSouthTexasProjectUnits1and2,Revision3,November17, 2008,whichevaluatesthetransportofgasvoidsinthepipingbetween strainerandECCSandCSpumps.Neitheracopyofthereferenced documentnoranyapplicabledetailsfromthereferencewereprovided totheNRCItwasalsonotdescribedhowitwasdetermined thatvoidswouldnotcollectinthestrainer.Pleaseprovideasum-maryoftherelevantsectionsofReference56describinghowitwas determinedthatvoidswouldnotcollectinthepumpsuctionpip-ing.Additionally,pleaseprovideinformationthatevaluateswhether voidscancollectwithinthestrainer,andiftheydo,howthee wasevaluated.

RequiredResponse,Pg.36952.Thelicenseesresponsetoquestion33oftheApril15,2014,RAI,statedthattheCASAGrandemodeloverestimatesthewaterlevel comparedtocomputeraideddesigncalculatedlevels.Thelicensee statedthattheerrorwillbecorrectedsothatfuturesubmittalscon-tainaccuratepoollevels.However,thelicenseealsoneedstoverify thatstrainersubmergenceisadequateandthatvortexing,deaera-tion,and"ashingevaluationsadequatelyre"ectthecorrectedlevels andthattransportisnotduetohigherpoolvelocities.Please provideinformationthatjusti"esthattheseareasarenotadversely RequiredResponse,Pg.37053.Thelicenseesresponsetoquestion34oftheApril15,2014,RAI,statedthattotalCSS"owisdeterminedbymultiplyingtherandom pump"owratebythenumberofoperableCSSpumps.These"ow ratesarerandomlyselectedfrombetweenthemaximumcalculated "owrateandsomeminimumvalue.Itwasnotclearthatusingrandom valuesisappropriateandhowtheminimumvalueswerecalculated.

Thelicenseealsostatedthatforalltwoandthreetraincasesthat CASAusesthehighertwotrain"ow,sinceitisconservative.Theli-censeeincludedreferencetoReference42,Volume3,5N109MB01024, DesignBasisDocumentContainmentSpray,Revision3,November 17,2004.Neitheracopyofthereferenceddocumentnoranyapplica-bledetailsfromthereferencewereprovidedtotheNRCPlease summarizetherelevantinformationfromReference42,providethe methodologyusedtodeterminetheminimum"owrates,orprovide thebasisforusingrandom"owratesforeacheventinsteadofcalcu-latingeventspeci"c"owrates.RemovedResponse,Pg.37054.Thelicenseesresponsetoquestion36oftheApril15,2014,RAI,statesthatstrainerbucklingisthelimitingfailurecriterionwhen comparedtoNPSH.Itwasnotclearthat"ashingwasconsideredas afailuremodeforthestrainerintheSTPsubmittal.Pleasestate how"ashingacrossthestrainerisevaluatedbyCASAGrandesince thisfailuremodemaybemorelimitingthanstrainerbucklingwhen the"uidtemperatureishigh.Forquestion41.c.oftheApril15,Tuesday1 stMarch,2016:19:32,Page106of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION2014,RAI,theNRChasacceptedtheuseofmitigativemea-surestoaddressdefense-in-depth.Thelicenseecreditedbackwashof thestrainersasamitigativemeasure.However,itwasfurtherstated thatthemitigativemeasuresforbackwashoftheECCSstrainershave notbeenproceduralized.Pleasedescribetheproceduralrequirements thatareinplacetoinitiateECCSstrainerbackwashorrevisethesub-mittaltoremoveitscredit.

RequiredResponse,Pg.37155.Forquestion41.c.oftheApril15,2014,RAI,theNRChasac-ceptedtheuseofmitigativemeasurestoaddressdefense-in-depth.

Thelicenseecreditedbackwashofthestrainersasamitigativemea-sure.However,itwasfurtherstatedthatthemitigativemeasures forbackwashoftheECCSstrainershavenotbeenproceduralized.

Pleasedescribetheproceduralrequirementsthatareinplacetoini-tiateECCSstrainerbackwashorrevisethesubmittaltoremoveits

credit.RequiredResponse,Pg.37255aCASAGrandeusesadistributionforthetemperatureatwhichchemicalareassumedtooccurandadistributionforthe conventionalheadlossbumpupfactor.Volume3statesthat chemicalareassumedtooccurbelow140Fandthattheconventionalheadlossbump-upfactoris5.Pleasestatewhich methodologyisintendedtobeusedandupdatethedocumenta-tionorthemodeltore"ecttheintendedmethodology.RemovedResponse,Pg.37256.CASAGrandedoesnotimplementthebedcompressionaspectsoftheNUREG-6224Correlation.Volume3,equations33-38implythatthe compressionfunctionisimplementedinCASAGrande.TheNRC understandsthatthisissuewasaddressedbyimplementinga limitingbedcompressionforalldebrisheadlosscalculations.Please verifythatthishasbeenaccomplishedandprovideupdatedresults basedontheupdatedmethod.Pleaseprovidethebasisfortheas-sumptionthatthelimitingbedcompressionchosenisappropriate.RemovedResponse,Pg.37257.TheNRChasseveralconcernswiththemodelusedfor"berpenetrationthroughthestrainer.Consideringtheissuesdescribedin thisRAI,theNRCdoesnothavehighlevelofcon"dencethat thedebrispenetrationmodelaccuratelyrepresentstheexpectedde-brispenetrationandin-vessel"beraccumulationthatcouldoccurin theplant.Pleaseprovideinformationthatjusti"esthattheCASA Grandecalculationsfor"berpenetrationaremeaningfulandrepre-senttheplantconditions:(a)Assumptionsandmodelingtechniquesregardingdebrisarrivaltimingand"ltrationmayresultinnon-conservativebypassre-sults.Intheresponsetoquestion6.b.oftheApril15,2014,RAI, thelicenseestatedthatearlyarrivalofdebrisatthestrainerre-sultedinhigher"ltrationandlowertotalbypass.Theresponseto RAI11bstatedthatdebristransportedduringpool"llisplaced directlyonthestrainerattheinitiationoftheLOCA.Thisis alsorelatedtothenon-intuitiveresultsfoundduringasensitiv-itystudyprovidedtotheNRCforreview.TheNRCTuesday1 stMarch,2016:19:32,Page107of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONbelievesthattheresultisnon-intuitivebecauseitisnon-physical.Debrisarrivaltimingshouldnothaveasigni"canton"ltra-tion,ifrealistictimingisused.Theunderstandsthatplacing "beronthestraineratthestartofrecirculationmaybeconser-vativewithrespecttoheadloss,butmaybenon-conservative withrespecttostrainerpenetration.TheNRChasdeter-minedthatassuminghomogeneousmixingof"berinthepoolat thestartofrecirculationratherthanassumingthatsome"ber transportstothestrainerpriortorecirculationislikelytobe moreconservative.TheNRCunderstandingisbasedonthe relativelyshorttimeduringwhichsigni"cantbypassoccursand thelongertimeoverwhichheadlossbecomesmorerisksigni"-

cant.Pleaseprovideinformationthatjusti"estheSTPapproach isconservativeorincorporateamethodologythatismoreappro-

priate.RequiredResponse,Pg.372(b)Iftheexistingmodeloramodelthatresultsinpenetrationbeinghighlydependentonarrivaltimingearlyintheeventismain-tained,pleasejustifywhythemodelisnotmorecorrelatedto theamountofdebrisarrivingatthestrainerregardlessoftim-ing.IfdebrisarrivingatthestrainerattheinitiationoftheLOCA thecalculatedbypassamountpleasejustifythismodelbe-havior.Doesthemodelassumethatearlyarrivingmaterialcan passthroughthestrainer?Ifnot,pleasejustifytheassumption.

Also,pleaseprovidejusti"cationthatlessdebriswouldbypass thestrainerintheplantifdebrisarrivesatthestrainerearlierin thescenario,thatis,themodelaccuratelyre"ectsplantperfor-

mance.RequiredResponse,Pg.372(c)Howaretheuncertaintiesresultingfromapplyingbypasstestresultstotheplantconditionaccountedforinthemodel?Are thereconditionspotentiallypresentintheplantthatwouldresult inmorebypassthanoccurredintherelativelycontrolledtest conditions?Pleaseexplain.

RequiredResponse,Pg.372(d)Howareuncertaintiesassociatedwiththestrainerbypasscalcu-lationaccountedfor?Thecalculationappearstobeverysensi-tivetoarrivaltiming.Also,howareuncertaintiesthatarisefrom testingandthetranslationoftestresultsintobypassmodelsac-countedfor?Pleaseexplain.

RequiredResponse,Pg.373(e)TheNRCnotedthatchangingthetimestepintheCASAGrandedebrispenetrationmodelhasasigni"cantonthe output(amountofdebrisreachingandaccumulatinginthecore).

CASAGrandeusesarelativelyinaccuratemethodtointegrate themassbalanceequationsfordebrisaccumulatedinthecore, especiallyearlyintheaccidentsequenceafterinitiationofrecircu-lation.Pleasedescribehowthelicenseedeterminedthatthetime stepintervalandintegrationmethodprovideappropriateresults (ideally,theconditionalprobabilityoffailurebyexceedanceof thecold-legbreak"berlimitshouldbeindependentofthecom-Tuesday1 stMarch,2016:19:32,Page108of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONputationaltimesteps).

RequiredResponse,Pg.373(f)TheNRCnotedthatoneinputparametertotheCASAGrandecodetocomputethe"ltrationisoneorder ofmagnitudemorethanthatdeterminedbytestinganddoc-umentedinVolume3ofthesubmittal(Table2.2.28,parame-term testtheupperboundis0.00037231/g;insteadavalueof0.0037231/gwasapparentlyusedintheCASAGrandecompu-tationsinsupportoflicensesubmittals).Theresultofthiserroris overestimationofthe"ltration,whichcausesunderesti-mationintheamountof"berpenetrationandin-vesselaccumu-lation.Sensitivitystudiessuggestthatthiserrorwouldunderes-timatethecold-legbreakin-vessel"berlimitfailurecontribution totheCDFbyaboutanorderofmagnitude.Pleaseexplainand includecomparisonsof"ltrationandsheddingrates computedbyMonteCarlosamplingtotestdatainyourresponse.

RequiredResponse,Pg.37458.TheNRCreviewedtherelationshipbetweenbreaksize,andCASAGrandefailurepredictions.Theresultsofthereviewindicate thattheremaybediscontinuitiesintheresultsthatsuggestthat failuresduetocertainbreaksizesarenotpredictedoraremuchless likelytooccurthanwouldbeexpected.Forexampleonebreaksized atabout5inchesresultsinafailure.Withrespecttobreaksize, noadditionalfailuresoccuruntilthebreaksizereachesabout10 inches.Thisbehaviorappearstobenon-physical.Pleasediscussthis observationandprovideanevaluationofwhetherthisbehavior theresultsoftheanalysis.RemovedResponse,Pg.37459.ItistheNRCsunderstandingthatthecomputer-aideddesign(CAD)modelusedtodeterminedebrisgenerationamountswasdevel-opedundera10CFR50,AppendixBprogram,andthereforetreats theoutputtobeaccurate.However,itmaynotbethecaseforthe debrisgenerationvaluesusedinCASAGrande.Pleasedescribethe methodologyusedtoimporttheCADvaluesintoCASAGrandeand provideinformationthatdescribeshowthedebrisgenerationamounts usedbyCASAGrandewerevalidatedtobeaccurate.Pleaseinclude informationthatdemonstrateshowtheinterfacesbetweentheCAD modeloritsinputtoCASAGrandewerevalidatedtobecorrectly implementedanddescribewhetherrawCADvalueswerevalidated tobethesameasthoseusedinCASAGrande.

RequiredResponse,Pg.37560.Section5.4.3ofthesubmittaldatedNovember13,2013,indicatesthatalmost100percentofthebreakscenariosgeneratelessthan10ft 3of"berglassdebris(theprobabilityofgeneratingmorethan10ft 3 issmallerthan10 12).Usingadensityof2.4 lbm ft 3,theequivalentmassof10ft 3of"beris24lbs(10.89kgs).TheNRCreviewoftheCASAGrandeprogramindicatesthattheremaybeasigni"cantnumberof casesthatgeneratemuchmorethan10ft 3of"berglass(hundredsanduptoone-thousandkg).whichappearstoimplythattheprobability ofgeneratingmorethan10.89kgof"berglassissmallerthan10 12 ,andclarifyifthisinformationwasusedintheCASAGrandemodel.Tuesday1 stMarch,2016:19:32,Page109of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONPleaseclarifyiftheinformationinFigure5.4.5inVolume3alsoincludeslatent"ber.

RequiredResponse,Pg.38261.ForbreaksthatarenotDEGBandareassumedtohaveahemi-sphericalZOI,pleaseexplainhowaretherobustbarrierstreated?

Forexample,ifthebreakisonapipenearthe"oorandoccurson thebottomofthepipe,isthepotentialfordamagefromare"ected jetaccountedfor?

RequiredResponse,Pg.38362.Duringreviewofthelicenseesresponsetoquestion9oftheApril15,2014,RAI,theNRCdevelopedanadditionalquestionregarding thetreatmentofdebrisintheheadlosscalculation.Pleaseclarifyif thesmalland"nedebrisaretreatedasiftheyhavethesameproper-tiesintheheadlosscalculation(correlation)?Inyourresponse,please clearlyexplainhoweachdebrissizeistreated?RemovedResponse,Pg.38563.BasedonthelicenseesresponsetoESGBquestion1.b.oftheApril15,2014,RAI,itappearsthatsomelargebreaks,manymedium breaks,andallsmallbreaksdonotgenerateenoughdebristoresult ina1/16-inchbedwhendistributedover3strainertrains.Please providethefollowinginformation:

-Distributionoflowdensity"berglass(LDFG)debrismassreach-ingthestrainersforsmall,medium,andlargebreaksseparately.

-Theamountoflatent"brousdebristhatreachesthestrainersforeachbreakcategoryandifitvaries,providethedistributionand methodologyusedtodeterminetheamounts.

-Therangeofthemassof"ne"brousdebrisandsmallpiece"brousdebrisgeneratedforeachofthebreakcategories.

-Therangeofthemassesofthese"bercategoriesthattransporttothestrainer.

RequiredResponse,Pg.38564.Basedonthereviewofthelicenseesresponsetoquestion2oftheApril15,2014,RAI,thehasidenti"edthefollowingconcern:

whatcausesthevariabilityintheheadlosscalculationperformedby thecorrelation?Forexample,scenariosthatcontainapparentlysim-ilardebrisloads(CASAGrandeCase1intheRAIresponse)may havesigni"cantlytcalculatedheadlosses.Theheadlosses fromthereferencedtestsrepresentCASAGrandevaluesinthe99th percentile,indicatingthatalmostallheadlossespredictedbyCASA Grandearelowerthanthetestresults.ThelimitingCASAGrande Headlosscalculationwas8.2feetforconventionaldebrisand161.9 feetfortotalheadloss,whichismuchhigherthanthetestresults.

Thesemaximumvaluesseemhigherthancouldpossiblyoccur,at leastforthetotalheadloss.Explainifthesemaximumvaluesrealis-ticoraretheynon-physicalpredictions.ExplainwhyCASAGrande predictslowerheadlossesthanthetestresultsover99percentofthe

time.RemovedResponse,Pg.38565.RG1.174statesthatlicenseesareexpectedtoevaluatewhethersuf-"cientsafetymarginswouldbemaintainediftheproposedlicensing basischangeweretobeimplemented.TheNRCrecognizesthatTuesday1 stMarch,2016:19:32,Page110of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsafetymargincannotbecharacterizedbyasinglenumberforatime-dependentanalysiswithmultiplefailuremodes.Instead,itcanbe representedbyanequationorrelationshipthatrepresentsthesafety marginasafunctionoftimeforeachofthesevenGSl-191failure modes.Forexample,thesafetymarginwithrespecttostrainerme-chanicalcollapsecanberepresentedas:

S m=9.35ftWhere S m=marginwithrespecttostrainermechanicalcollapse=dtialpressureacrossstrainerasafunctionoftimePleasedescribewhetherCASAGrandecalculatessuccesswithre-specttoeachofthesevenGSl-191failuremodesinamannerthat isconsistentwithRG1.174guidanceonsafetymargins.Speci"cally, pleaseidentifythefailurethreshold(worstallowablevalue)foreach failuremodeandstatewhetheritisconsistentwithexistinglicensing basiscalculations.RemovedResponse,Pg.38566.Assumption1jofVolume3statesthatswitchovertohotlegin-jectionwouldoccurbetween5.75and6hoursafterthestartof theevent.Assumption11astatesthecurrentSTPdesignba-sisevaluationmethodologyusedtocalculatetherequiredhotleg switchovertimingisappropriatewiththeexceptionofGSl-191related phenomenon.Whenanalyzingboricacidprecipitationinregardsto post-LOCAlong-termcorecooling,themixingvolumeandpercent-ageofvoidsinthecoreusedintheanalysesneedtobejusti"ed.Im-propermodelingcouldresultinnon-conservativeliquidvolumeafter aLOCA.Ultimately,thiscouldimpactthehot-legswitchovertime inaplantsemergencyoperatingprocedures.STPscalculationfor hot-legswitchovertimefollowingaLOCA(NC-7136,Revision1)was providedinresponsetoSNPBRAI4.Aninputforthiscalculation isliquidvolumeintheRCS.Pleaseprovidethemixingvolumeand percentageofvoidsinthecoreforSTPlicensingbasiscalculations usedtodeterminetheliquidvolumeintheRCSforhotlegswitchover timinginthecalculationtovalidateassumptions1jand11a.Please justifytheuseofthesenumbersandanyassumptionsmade.The licenseecanrefertoNRC-approvedmethods,asappropriate.

RequiredResponse,Pg.3861.4.7STSBTechnicalSpeci"cationBranch4.

Background:

InresponsetoNRCcomment/question2.4(page6of179,Volume6.2),thelicenseestatedthefollowing:Adescriptionofhowtheproposedchangewillctthetechnicalspeci"cationsisprovidedinRegulatoryEvaluation Section4.1.3intheLARprovidedinEnclosure3.Asdis-cussedinmoredetailinEnclosure3,nochangestooper-abilityrequirementsforctedsystemsandnochangesto theexistingtechnicalspeci"cationActionStatementsarepro-posed.Proposedchangestothetechnicalspeci"cationbasesTuesday1 stMarch,2016:19:32,Page111of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthatconformtothechangesinthelicensinganddesignbasesareincludedinAttachment3toEnclosure3forinfor-

mation.Page1of1ofAttachment3toEnclosure3ofthelicenseeslet-terdatedNovember13,2013,TechnicalSpeci"cationsBasesPage Markups,states,inpart:UFSARAppendix6Aprovidesarisk-informedapproachthataddressesthepotentialofdebrisblockageconcludingthat long-termcorecoolingfollowingadesignbasislossofcoolant accidentisassuredwithhighprobability.UFSARAppendix 6Aalsoprovidesguidanceforassessingthepotentialimpact onOperabilityduetounexpectedmaterialsuchasloosede-brisdiscoveredincontainmentthatmaycontributetodebris loadingonthestrainers.Page15of16ofAttachment2toEnclosure3ofthelicenseesletterdatedNovember13,2013,"STPEGSUFSARPageMarkups"states, inpart,thefollowing:Thetableprovidesguidancethatmaybeusedtoimmedi-atelyassessthepotentialimpactduetounexpectedmaterial discoveredincontainmentthatmaycontributetodebrisload-ingonthestrainers.AsdiscussedinReference6A-4[licensee letterdatedJune19,2013],thesevaluesarenotnecessarily thelimitingamountofeachtypeasanalyzed.Conservatisms inthereportedvaluesarealsodiscussedinReference6A-2

[licenseeletterdatedDecember11,2008].Therefore,acon-ditionthatmayexceedthevaluesshowninthetabledoesnotprecludereasonableexpectationofoperability.DebrisTypeInputParameterValueMinimum(Reference6A-6)MarginLatentdebris,consistingof:200lbm(Total)40lbm(Total)

• Dirtand/ordust170lbm(1.0cubicft)34lbm(0.2cubicft)

• Fiber,e.g.,"brousinsulation100sq-ft6lbm(2.5cubicft)Miscellaneousdebris,includingbutnotlimitedtounquali"edtagsandlabels100sq-ft10sq-ftUnquali"edcoatingsTable6.1-4100sq-ftPage26of31ofEnclosure3toaletterfromSTPdatedNovember13,2013,states,inpart,thefollowing:Whenwarranted,animmediateoperabilitydeterminationwillbefollowedbyapromptoperabilitydeterminationthat willapplyadditionalinformationandsupportinganalyses tocon"rmtheimmediateoperabilitydetermination.Evalu-ationsmayconsideradditionalinformationprovidedinthe inputstotheCASAGrandeanalysisaswellastheiden-ti"edconservatismsassociatedwiththecategoriesofmajor assumptionsintheCASAGrandeanalysis,Section3ofVol-ume3(Enclosure4-3).Tuesday1 stMarch,2016:19:32,Page112of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONForadiscoveredconditionthatpotentiallyctsdebrisquantitiesincontainment,theapplicableCASAGrandein-putparametersandassumptionsprovideameansforimmedi-ateoperabilitydeterminationsandfollow-updeterminations, aswarranted,toevaluatetheimpactoncontainmentsump performance.

Concern:ItistheNRCspositionthatwhenevaluatingoperabil-ityofanSSC,theuseofriskassessmentorprobabilitiesofoccurrence ofaccidentsoreventsisunacceptable.Thede"nitionofoperability isthattheSSCsmustbecapableofperformingtheirspeci"edsafety functionorfunctions.Thisinherentlyassumesthattheeventoccurs andthatthesafetyfunctionorfunctionscanbeperformed.Oper-abilityisnotindeterminate.AnSSCrequiredtobeoperablemustbeabletoperformitsspeci"edsafetyfunctionoritisinoperable.TheNRCisconcernedthattheCASAGrandedesigninputs(parametersandassumptions)referredtoinReference6A-5ofthe UFSARMarkupincludesprobabilityaspectsthelicenseeproposes tobeacceptabletobeusedduringanoperabilitydeterminationif aconditionisdiscoveredthatpotentiallydebrisquantitiesin containmentandtheneedarisesforevaluatingtheimpactoncon-tainmentsumpperformance.

Request:providethefollowingadditionalinformation:1)AnexplanationofhowtheassumptionsreferredtoinReference6A-5oftheUFSARMarkupanddiscussedinSection2.2ofVol-ume3ofthesamedocumentwillbeusedduringanoperability determination.Pleaseincludeanexampletotheextentpractical.2)Ifthelicenseeisproposingtoallowtheuseofriskinformationintheassessmentofoperability,then:a.Pleaseprovideadescriptiondemonstratingtherelationshipbetweenprobabilityandoperabilityforeachoftheassump-tionsdiscussedinSection2.2ofVolume3.b.PleaseexplainhowwouldtheprobabilityofoccurrenceofeachoftheassumptionsdiscussedinSection2.2ofVolume 3changetoimproveordegradetheimpactoncontainmentsumpperformance.

RequiredResponse,Pg.388Tuesday1 stMarch,2016:19:32,Page113of393 DRAFTPart2RAIResponses(Round1)2.1ML14149A434,Firstsetofresponses2.1.1APLABResponses2.1.1.1APLAB,CASAGrande,LOCAFrequencies:Question1 STPResponseto1a,(Item1a,Page36)Doublecountingofannualfrequencyforanybreaksizeisexplicitlyprevented bythehybridmethodologythatpreservestheexceedancefrequencydistribu-tionsfromNUREG-1829.Althoughthetotalfrequenciesarepreservedforany breaksizegiveninNUREG1829,therebypreventing"doublecounting",the frequenciesatanyspeci"cweldlocationwereweightedaccordingtothedegra-dationmechanismsasdescribedintheLAREnclosure4-3,Section5.3.Bythis method,locationsexposedtomoredegradationmechanismsareappropriately assignedagreaterfractionofthetotalfrequency(forthatbreaksize).STPResponseto1b,(Item1b,Page37)TheexceedancefrequenciesgiveninNUREG1829thatincludenon-pipingcom-ponentcontributionwerepreservedandthereforecontributionsfromnon-piping componentswereincludedintheanalysis.Debris-relatedriskfromnon-pipingcontributorswasexaminedfromtwoper-spectives:(1)potentialfordebrisformation,and(2)proximityofnearbywelds.

Potentialfordebrisformationisbyboththepotentialmagnitudeofthe breakandbytheproximityofinsulationtargets.Forexample,ReactorCoolant Pump(RCP)sealleakswerejudgedtobecomparabletoSBLOCAintermsof potentialforgeneratinginsulationdebrisinthevicinityoftheRCP.Pressur-izerReliefTank(PRT)reliefvalveopeningwasjudgedtohavehigherdamage potentialbutverylittlecollocatedinsulationthatcanbedamaged.Becauseoverallinitiatingeventfrequenciesarepreserved,itismostimpor-tantthatpipeweldsofcomparablesizetothenon-pipingcontributorsarelocated inthesameproximityasthenon-weldcontributorsofinterest.Weldsonlarge pipesareassignedafullrangeofbreaksizes,sotheyprovidesuitablesurrogate coordinatesforotherruptureeventsthatmayoccurinthesamevicinity.For example,the"rstweldonhotandcoldleglinesrepresentsastlocation forreactornozzlerupture.The775weldsconsideredinthepipebasedLOCAfrequencyanalysisare"nelydistributedoverallthelocationsinthecontainmentwheresigni"cant debrisgenerationisexpected.Non-pipingcomponentsthatmaycontributeto aLOCAincludenozzles,componentbodies,pressurizerheatersleeves,man 114 DRAFTPART2.RAIRESPONSES(ROUND1)ways,controlroddrivemechanismpenetrations,safetyandreliefvalves,reactorcoolantpumpseals,reactorvessel,pressurizervessel,steamgeneratorvessels, weldedcapsonretiredlinesandothercomponents.Withtheexceptionofnon-pipecomponentsthatarelocatedinthereactorcavity,allthesenon-pipecomponentsarelocatedatornearpipewelds.For exampletherearemanyweldlocationsinlinesaroundthepressurizervesselin-cludingthesurgeline,spraylines,andthesafetyandreliefvalvelinesthatwould beavailabletosimulatenon-pipecomponentsinthatareaofthecontainment.

Inadditiontherearemanyweldsdistributedalongthecoldlegsincludingthose nearthereactorcoolantpumpsthatwouldsimulatenon-weldlocationsinthose areas.Themodeledweldsthatarelocatedatthesafeendsofthenozzlesatthe reactorvessel,pressurizervessel,andsteamgeneratorvesselarereasonablyclose totheassociatednozzleweldsandarecloseenoughtothevesselstoproducea signi"cantdebris"eldfromtheinsulationaroundthosevessels.Onecategoryof non-pipecontributionstoLOCAfrequencythatisnotlocatednearamodeled weldlocationwouldbethatassociatedwithnon-pipecomponentsassociated withthereactorvessellocatedawayfromthehotlegandcoldlegnozzles,e.g.controlroddrivepenetrations,manways,andinstrumentlinesconnectedtothe reactorvessel.Howeverthesearelocatedinthereactorcavitywhichwasnot foundtobeanimportantlocationforgeneratingatransportabledebris"eld.2.1.1.2APLAB,CASAGrande,LOCAFrequencies:Question3 STPResponse(Item3,Page37)Thebinsizesaredeterminedbythefollowingstepsforeachweldcase:1.InterpolatetheCCDFofbreak-sizefrequencyto"ndtheexceedancefre-quencycorrespondingtoeachLOCAcategorylimit(0.5in.,2in.,6in.).2.DivideintologarithmicallyequalbinstheexceedancefrequencyintervalforeachLOCAcategoryusingthenumberofbinsdeterminedforeach LOCAcategory.3.Invertthelogarithmicbinintervalsbyinterpolationto"ndthecorrespond-ingbreaksizeintervals.Asanexample,Equation25andEquation26ofLAREncl.4-3(Pg.150)canbeusedto"ndthenumberofsmallandmediumbreakswithauserspeci"ed numberof10largebreaks(NL)andamaximumpipediameterincontainment of31.5inches.SolvingEquations25and26forthenumberofsmall(Ns)and mediumbreaks(NM)yieldsNs=landNM=2,respectively.Figure5.3.4shows thatthenumberofbreaksforsmall,medium,andlargebreakshavebeendis-tributedequallyinthelogofexceedancefrequency(yaxisofplot)withintheir respectiveLOCAsizecategory.Usingequallogarithmicspacingcreatesnonuniformprobabilityweightsthatmustbecarriedwitheachsampledbreaksize.Usingequallogarithmicspacing tosamplearapidlydecliningCCDFalsoforcessamplestooccurintheupper endofeachLOCAcategorythatwouldotherwisehaveaverysmallprobability ofbeingselected.Tuesday1 stMarch,2016:19:32,Page115of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.1.3APLAB,CASAGrande,LOCAFrequencies:Question4STPResponse(Item4,Page37)Reference8toEnclosure4-3wasprovidedincorrespondencedatedDecember 23,2013(ML14015A311).Reference7wasprovidedtotheNRCinsupportofameetingonOctober3,2011,andisavailableinNRCsAgencywideDocumentsAccessandManagement System(ADAMS)viaAccessionNumberML112770237.DetailsregardingapplicationofthedocumentsaregiveninEnclosure1tothisattachment.2.1.1.4APLAB,CASAGrande,toPRAInterface-General:Ques-tion1aSTPResponse:(Item1a,Page38)Failuremechanism4,Debrispenetrationexceedsex-vesselelimitscausingavarietyofpotentialequipmentandcomponentfailuresduetowearor clogging,wasaddressedbyareviewofSTPNOCsdeterministicevaluationof thephenomena.TheEx-vesseleDownstreamevaluationwaspreviouslyprovidedinSTPLetterNOC-AE-08002372,Supplement4totheResponsetoGeneric Letter2004-02,datedDecember11,2008(ML083520326).Ex-vesseldownstreamwerereviewedforadequacyundertherisk-informedapplication,andnoadditionalorunusualSTP-speci"cvulnerabilities toex-vesselewereidenti"ed.Reviewofthedeterministicex-vessele analysiswasperformedtoaddresstherequirementsofRG1.174intermsof potentialtotheplantlicensingbasis.FailureMechanism6,Buildupofoxides,crud,LOCA-generateddebris,andchemicalprecipitatesonfuelcladdingexceedsthelimitsforheattransferre-sultinginunacceptablyhighpeakcladdingtemperatures,wasnotexcluded fromtheriskassessment.IntheSTPLARanalysisofex-vesseleoxides, crud,LOCA-generateddebris,andchemicalprecipitateswerenotmodeledas explicitlyasotherphenomenology.However,anestimateofcrudreleaseduring aLOCAtransientwasintroducedasaparticulatesourcethataccumulatesin thedebrisbedandheadloss.TheSTPLARusedanindustrynominal crudreleaseinventoryof24Ibm.Intherisk-informedcontext,ECCSfailuresinitiatedbymechanisms4and6arejudgedtobelessprobablethanthemostunlikelyinitiatorsthatarecon-sideredinthestudy(ex.LBLOCA).2.1.1.5APLAB,CASAGrande,toPRAInterface-General:Ques-tion1bSTPResponse:(Item1b,Page38)OtherfailuremechanismsandassumptionsrelatedtoGSI-191phenomenathatrelyondeterministicacceptancecriteriawereincludedaspointvaluesand werenotvariedacrossphysicallyplausiblerangesincluding,butnotlimitedto:1.ZOIsize 2.LatentdebrisquantitiesTuesday1 stMarch,2016:19:32,Page116of393 DRAFTPART2.RAIRESPONSES(ROUND1)3.Core"berlimitsrelatedtoboron,4.NPSHassumptionsAlthoughthesevalueshavebeenusedasindividualfactorsinpreviouslysubmitteddeterministicanalyses,theywereincluded,andareconsideredfor theirpotentialriskimpact.2.1.1.6APLAB,CASAGrande,toPRAInterface-General:Ques-tion3STPResponse:(Item3,Page38)Section9ofEnclosure4-2toReference1ofthecoverletter(i.e.,Volume2)describeswhatismeantbythefrequencyofsuccessfulpumpcombinationstates andpresentsthefrequenciesforeachstate.Brie"y,thesefrequenciesareforthe sumofmediumandlargeLOCAsequencesrequiringsumprecirculation,also foundnottoresultincoredamageintheabsenceofGSI-191phenomena,and eachfrequencyisforanexclusivecombinationforthenumberofECCSpumps running.ThefrequenciesinthePumpStateFrequencycolumnofTable2.2.11 comedirectlyfromcolumn2ofTable9-1inVolume2,thoughtheyareresorted bythenumberofpumpsworkingratherthanbythefrequencyofeachpump state,asinTable9-1ofVolume2.TheprobabilitiesfortheoccurrenceofthetGSI-191phenomenacienttocausefailurearederivedbyCASAGrandeseparatelyfordtECCS pumpcombinationstates.Onlythehighestfrequencyrankedpumpcombina-tionstateswereevaluatedsincethosearetheoneswiththegreatestpotential toincreasecoredamagefrequency.Forexample,thereisnoneedtoevaluate pumpcombinationstateswherethelowpressureinjectionpumpsallfailsince suchcombinationsalreadyleadstocoredamage,independentoftheGSI-191 phenomena.ThePRAmodelsapplytheseprobabilitiesalongeachsequencein thePRAmodeltodeterminethefrequencyofsequencesresultingincoredam-ageduetoGSI-191phenomena.ThePRAmodelsdonotusethefrequencies ofthesestates;ratherthefrequenciesareonlyusedtodeterminewhichpump combinationstatestobeevaluatedbyCASAGrande.Fivepumpstateswere analyzedinCASAGrande.ForthosesuccessfulpumpstatecombinationsnotevaluatedbyCASAGrande,thePRAconservativelyassumedthatallcorrespondingsequencesthenleadto coredamagewithprobability1duetoGSI-191phenomena.2.1.1.7APLAB,CASAGrande,toPRAInterface-General:Ques-tion4aSTPResponse:(Item4a,Page39)Yes,theprobabilitiesofvariousdebris-relatedfailuremechanismsareentforscenarioswheresomecontainmentsystemsdonotoperateasassumed.

However,nocreditistakenintheanalysisforcontainmentpressureaboveva-porsaturation,solackofcontainmentisolationdoesnottheconditional probabilityofECCSfailurecalculatedbyCASAGrande.ConditionalprobabilityofECCSfailuredependsonsumptemperaturehis-toriesthatarebycontainmentsystemperformance.Thermalhydraulic analyses(LAREncl.4-3,Ref.5)havefocusedonnominalcontainmentoperatingTuesday1 stMarch,2016:19:32,Page117of393 DRAFTPART2.RAIRESPONSES(ROUND1)conditions,butsomecontainmentfailurestateshavebeenassessed.ConditionalprobabilityofECCSfailureunderdegradedcontainmentsystemperformance isinherentlytfromtheconditionalprobabilityofECCSfailureunder nominalconditionsbecauseoftheequipmentfailurefrequenciesthatareintro-duced.ConditionalprobabilityofECCSfailureunderdegradedconditionscan alsovarybecauseofphenomenologicaldependenceontemperature,including chemicalcorrosionandprecipitation,NPSHAvailable,anddegasi"cationpoten-

tial.Currentanalysesassumeasinglerepresentativetemperaturehistoryforsmallandmediumbreaksandasinglerepresentativetemperaturehistoryforlarge breaks,allcomputedfornominaloperatingconditions(LAREncl.4-3,Figure 2.2.1,Pg.46).Thisapproachimplicitlyassumesthattheoccurrencefrequency foralternatetemperaturehistoriesisverysmall.ThePRAcanprovideabasis forweightingthefrequencyofcontainmentequipmentfailureinmuchthesame waythatthePRAprovidesabasisforweightingthefrequencyofpumpfailure states,buttheweightassociatedwithcomplexcombinationsofequipmentfailure rapidlydeclines(LAREncl.4-2,Section10).2.1.1.8APLAB,CASAGrande,toPRAInterface-General:Ques-tion4bSTPResponse:(Item4b,Page39)PotentialinECCSfailureprobabilitycausedbycontainmentsys-temfailurestatesarenotaddressedexplicitlyinthePRAbecausethePRA modelconsiderstheprobabilityofcontainmentsystemfailuresindependentof thesumpfailureprobabilitiesgeneratedbyCASAGrande;i.e.,thesystemfailure probabilitiesarenotmodi"edbasedonanyGSI-191relatedeTheprob-abilityofcontainmentisolationorfancoolersuccessisnotbyGSI-191 phenomena.Section10ofVolume2(LAREncl.4-2)describestheresultsofsen-sitivityanalysistojustifytheapproachassumed.Tosummarizethatdiscussion; thefrequencyofmediumorlargebreakLOCAswithdegradedcontainmentsys-temstates,andwhichavoidcoredamage,isverylow.SinceGSI-191phenomena canonlyincreasecoredamagebymovingaportionofthesesuccesssequences tocoredamage,thecontributionofsuchsequenceswithdegradedcontainment systemstothetotalGSI-191phenomenaimpactisevensmaller.2.1.1.9APLAB,CASAGrande,toPRAInterface-General:Ques-tion4cSTPResponse:(Item4c,Page39)Thedtcontainmentfailuremodesreferredtoinhigh-levelrequirementHLRLE-EarethoselistedinTable2-2.8-9ofTheASMEPRAStandard.The STPPRAisafullLevel1-Level2studythatalsoevaluateslargeearlyrelease frequencyconsistentwiththeTheASMEPRAStandard.Theactivecontain-mentsystemfailuresarefullyrepresentedintheSTPPRAasarethephenomena requiredbyTable2-2.8-9.WhiletheanalysisinCASAGrandeassumedsuccess oftheactivecontainmentsystemsforpurposesofcomputingtheconditional probabilitiesoffailinganyofthe7failuremodesofGSI-191,theSTPPRAcon-sideredallsuchfailures.IfinagivenPRAsequence,theGSI-191phenomena ledtothefailureofsumprecirculation,thisimpactwasaccountedforintheTuesday1 stMarch,2016:19:32,Page118of393 DRAFTPART2.RAIRESPONSES(ROUND1)performanceofcontainmentsprayrecirculationwhendeterminingthesequenceLevel2endstates.TheGSI-191phenomenahavenoimpactontheprobabilities ofsuccessfulfancooleroperation,norofcontainmentisolation.2.1.1.10APLAB,CASAGrande,toPRAInterface-General:Ques-tion5STPResponse:(Item5,Page39)ItwasnotconcludedthatonlymediumandlargeLOCAswouldrequiresumprecirculation.ItwasconcludedthatonlymediumandlargeLOCAswouldboth requiresumprecirculationandpotentiallybebyGSI-191phenomena.

SmallLOCAswhichalsorequirerecirculationaremuchlesslikelytobe becausetheamountofdislodgeddebrisismuchlessandcontainmentspray isnotautomaticallyactuatedforsuchscenarios.Containmentsprayisneeded totransportthecontainmentlatentdebrisandanydislodgedinsulationtothe

sump.SincetheinitialpreparationofVolume2(LAREncl.4-2),ithasbeencon-"rmedthatonlylargeLOCAscenariosareabletochallengeECCSperformance metricsatSTPasshowninFigure1.ECCSperformancemetricsaddressphysi-calphenomenaassociatedwithdebris-inducedon(1)strainermechanical buckling,(2)NPSHmargin,(3)degasi"cation,(4)core"berinventoryassoci-atedwithblockageforhotlegandcoldlegbreaksand(5)core"berinventory associatedwithonsetofboronprecipitationforhotlegandcoldlegbreaks.None oftheuser-speci"edthresholdsfortheseperformancemetricsarechallengedby smallandmediumbreakscenariosatSTP.Becausetransportfractionsandfailed coatingssourcesarelargelyconstantforallscenarios,successfulperformanceof smallandmediumbreakscenariosisattributedtosmallerinsulationdebrisvol-ume.LAREncl.4-3(Volume3)Assumption1ic,page82of248correctlystates thatboronprecipitationfailureswerenotexplicitlyprecludedforsmallbreaks (eithercoldlegorhotleg),andinfact,werenotprecludedforanycoldleg breaks.LAREncl.4-3Assumption11dstatesthatmediumandlarge,andin factall,hotlegbreakswereprecludedfromboronprecipitation.Assumption 11dcontributestothesuccessstatesofsmallandmediumbreaks,butdoesnot overridethedominantconsiderationofsmallerdebrisvolume.2.1.1.11APLAB,CASAGrande,toPRAInterface-General:Ques-tion6aSTPResponse:(Item6a,Page40)Fifteen(15)samplesofthebreakfrequencyvs.sizecurvesweregeneratedforeachpumpstateanalyzedintheSTPstudy.Theinconsistencyinthedoc-umentsectionshasbeenenteredintheSTPcorrectiveactionprogramtotrack correctionforfuturesubmittals.2.1.1.12APLAB,CASAGrande,toPRAInterface-General:Ques-tion6bSTPResponse:(Item6b,Page40)TablessuchasTable6.2ofLAREncl.4-3werepassedtothePRAforeachofthe"veplantfailurestates.ThetablesaregeneratedasstandardCASAGrande outputwiththenames:Tuesday1 stMarch,2016:19:32,Page119of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:ECCSsuccess(green)andfailure(red)asafunctionofbreaksize.BluedashedlinesmarkthesmallestbreakthatcanchallengeECCSperformancemetrics andthelargestbreakthatcanpassECCSperformancemetrics.DistOfCondBlockFailProbDistOfConBoronFailProb DistOfConSumpFailProb DistOfConTotalFailProbTheycontainindependentpointestimatesofmeanfailureprobability(un-sorted)andtheweightsassociatedwitheachsamplefromthetruncatedJohnson uncertaintyenvelopede"nedforannualfrequencyasafunctionofbreaksize.2.1.1.13APLAB,CASAGrande,toPRAInterface-General:Ques-tion6cSTPResponse:(Item6c,Page40)Thestatementonpage84ofVolume2(LAREncl.4-2)iscarriedoverfromanearlierdraftoftheanalysiswhere5pointswereusedtorepresentthe failureprobabilitydistributionsfortopeventsSUMP,FBLK,andBORON.The LARcalculationisbasedon15pointsasdescribedinSection6ofVolume 3(LAREncl.4-3)foreachofthesethreetopevents.TheVolume2statement shouldread:"Theuncertaintyinthesefailureprobabilitiesisreportedasdiscrete probabilitydistributionswith15pointseach."Asnotedabove,thishasbeen enteredintheSTPcorrectiveactionprogramtotrackforcorrectioninfuture

submittals.2.1.1.14APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1STPResponse:(Item1,Page42)IntheSTPPRA,isolablesmallLOCAsreferstothesetofsmallLOCAsoriginatinginthepressurizerPowerOperatedReliefValve(PORV)lineswhichTuesday1 stMarch,2016:19:32,Page120of393 DRAFTPART2.RAIRESPONSES(ROUND1)canbeisolatedbyclosingtheassociatedPORVblockvalve.Thefrequencyofsucheventsistakentobe9.2E-4peryear.Sincethetimeavailableforactionand thepowernecessarytoclosetheblockvalveisdependentonthefullscenario, creditforisolationoftheLOCAbyclosingofthePORVblockvalveisonlytaken attheendofthesequence.TheoperatoractiontoclosethePORVblockvalveis assignedahumanerrorprobabilityof1.58E-5,butitisonlyappliedwhenpower isavailabletotheblockvalveandhighpressureinjectionissuccessfulallowing nearly10hoursbeforeRefuelingWaterStorageTank(RWST)depletionfora successfulresponse.Assumption3.cinVolume3couldbebetterstatedtosaythatifleftuniso-lated,isolableLOCAsmayrequiresumprecirculation.Creditingisolation,how-ever,wouldgreatlylowerthefrequencyoftheisolableLOCAsequencesrequiring sumprecirculation.SincetheisolableLOCAsoriginateinthepressurizerPORV line(typicallyasleakagepastthePORVsthemselves),theydischargetothe PressurizerReliefTank(PRT).Therefore,theyarenotexpectedtodislodge appreciabledebris,andbybeingwithinthesmallLOCAsize,theywouldnot actuatecontainmentspray.Thecombinationofbeingittogeneratea sprayactuationsignalandnotdislodginganyappreciabledebrisisthebasisfor notconsideringisolableLOCAsfurther.2.1.1.15APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2STPResponse:(Item2,Page43)CASAGrandedoesnotcurrentlyconsiderthepotentialforthenumberofrunningpumpstochangebasedonindicationsofdebrisbuildup.Theonly changeinpumpstatuscurrentlyaddressedissecuringspraysaccordingtothe EmergencyOperatingProcedures(EOP).2.1.1.16APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4aSTPResponse:(Item4a,Page43)AtableoftheprobabilitiesoffailingtopeventBORONandtheassociatedstatusofbreaksize,breaklocation,statusofhotlegrecirculationswitchover, andECCSpumpstatesisprovidedbelow.Thenumberofhighheadpumps, lowheadpumps,andspraypumpsoperatingineachpumpstateisindicated.

TheCASAGranderesultsaccountforthelocationofthebreak(i.e.,hotorcold leg)whendeterminingtheprobabilityofcore"owblockageforagivenbreak size.TheCASAGranderesultsareuseddirectlyforthesplitfractionsoftop eventBORONwhenhotlegrecirculationswitchoverissuccessful;asitssuccess precludesexcessiveboronprecipitationatlatertimes.Whenalignmentforhot legrecirculationfails,excessiveboronprecipitationleadingtocore"owblockage isassumedtoleadtocoredamagefortheproportionofbreakslocatedinthe coldlegs.Thecoldlegproportionsofthebreaksizeareasdeterminedinthe samplingwithinCASAGrande;i.e.,0.381forMediumLOCAsand0.256for LargeLOCAs.

SplitFraction IDSplitFractionValue-ProbabilityofCore FlowBlockageBreakSizeStatusofHotLegRecircu-

lationBreakLocation (Cold/Hot)

Applicable Pump State(s)BORML0.381MediumFailed0.381coldlegfractionfor MediumLOCAsAllpump statescontinuednextpage...Tuesday1 stMarch,2016:19:32,Page121of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued SplitFraction IDSplitFractionValue-ProbabilityofCoreFlowBlockageBreakSizeStatusofHotLegRecircu-lationBreakLocation (Cold/Hot)

Applicable Pump State(s)BORLL0.256MediumFailed0.256coldlegfractionforLarge LOCAsAllpump statesBML1S0MediumSuccessCASAresultforpumpstate1Pumpstate1:H3L3S3BML9S0LargeSuccessCASAresultforpumpstate9Pumpstate9:H3L1S3BML22S0MediumSuccessCASAresultforpumpstate22Pumpstate22:H2L2S2BML26S0MediumSuccessCASAresultforpumpstate26Pumpstate26:H2L1S2BML43S0MediumSuccessCASAresultforpumpstate43Pumpstate 43BLL1S1.25X10 3LargeSuccessCASAresultforpumpstate1, considersfraction incoldlegPumpstate1:H3L3S3BLL9S1.04X10 5LargeSuccessCASAresultforpumpstate9, considersfraction incoldlegPumpstate9:H3L1S3BLL22S2.54X10 4LargeSuccessCASAresultforpumpstate22, considersfraction incoldlegPumpstate22:H2L2S2BLL26S3.07X10 4LargeSuccessCASAresultforpumpstate26, considersfraction incoldlegPumpstate26:H2L1S2BLL43S1.04X10 5LargeSuccessCASAresultforpumpstate43,considersfractionincoldlegPumpstate 43BMLGF0.381MediumEither0.381coldlegfractionfor MediumLOCAsAllother pump statesBLLGF0.256LargeEither0.256coldlegfractionforLarge

LOCAsAllother pump states2.1.1.17APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4bSTPResponse:(Item4b,Page44)Forreference,Generalassumption1.jfromVolume3states:Itwasassumedthatswitchovertohotleginjectionwouldoccurbetween5.75and6hoursafter thestartoftheevent.Thisisareasonableassumptionsincetheswitchover procedureisstarted5.5hoursafterthestartoftheeventandtimingofEOP stepcompletion,switchoverforbothtrainscanbecompletedwithin15minutes.Thehumanerrorprobabilityfortheactiontoswitchoverforhotlegrecircu-lationisrepresentedbydatavariableHEHLR.Reference1documentsthequan-ti"cationofthishumanerrorprobability.ThehumanreliabilityanalysisassumesTuesday1 stMarch,2016:19:32,Page122of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatthescenarioresultsfromaLargeLOCA.IfRCSpressureremainsabove415psigbythetimetheoperatorsreachstep21ofOPOP05-EO-EO10Rev.22, thentheoperatorswouldinsteadtransfertoOPOP05-EO-ES12,POSTLOCA COOLDOWNANDDEPRESSURIZATION.However,forthelargerLOCAs, theinitiationofHotLegRecirculationiscuedfromOPOP05-EO-EO10Rev.

22,Step28whichproceduredirectstheoperatorstogoto0POP05-EO-ES14, TRANSFERTOHOTLEGRECIRCULATION,at5.5hours.Theoperators aredirectedtotransfertheHighHeadSafetyInjection(HHSI)tohotlegrecircu-lationbyenergizeandopenaHHSIhotleginjectionMOVandthenclosingthe HHSIcoldleginjectionvalve.TheprocedurethenalignstheLowHeadSafety Injection(LHSI)bylocallyenergizeaLHSIcoldleginjectionMOV(redundant stepisinOPOP05-EO-EO10step27),energizeandopenaLHSIhotleginjec-tionMOVfromtheControlRoom,andthenalsofromthecontrolroomclose theLHSIcoldleginjectionMOV.AcautionatthebeginningofOPOP05-EO-ES14directsthatoneSItrainistoremainalignedforcoldlegrecirculationin casetheLOCAwasaruptureofanRCShotleg.AllremainingSItrainsare tobealignedforhotlegrecirculation.TheEPRIHRACalculatorwasusedto computeatotalHEPforthisactionof3.6x10-5asdocumentedinReference 1.Bothcognitiveandexecutionerrorswereconsideredintheassessment.The timeavailableforactionfollowingthecuewasassumedtobe2hours,although theexpectedtimetocompletionisjust15minutes.Creditwastakenforaction recoverybytheemergencyresponseorganizationsincetheactionwouldtake placewellafter1hourfromthestartoftheaccident.OnlyoneHEPwasfoundnecessarytoaccountforthefactorsnoted.Eachofthesefactorsisdiscussedbelow.LOCAsize-ThisactionisonlyrequiredforthelargerbreakLOCAs;i.e.,forMediumandLargeLOCAs.ItisnotrequiredforSmallLOCAsbecausetheRCS pressurewouldremainabove415psig.Theinitiationcueandtimeavailablefor actionisnotdependentonthespeci"cbreaksizesojustoneactionwasassessed.Plantcon"guration(e.g.,numberofpumpsavailable)-Theproceduralguid-ancedirectinghotlegrecirculationswitchoverisonlypartlydependentonthe numberofpumpsavailable.IfonlyonetrainoftheLHSIpumpsisoperatingin thecoldlegrecirculationmodeat5.5hoursafteraccidentinitiation,thenhotleg recirculationswitchoverwasassumedfailed.Thisisconsistentwiththecaution inOPOP5-EO-ES14,TRANSFERTOHOTLEGRECIRCULATION.Ifmulti-pleLHSIpumpsareoperatingincoldlegrecirculationmode,thenallbutoneis creditedincompletingthetransfertohotlegrecirculationtoanRCSloopthat remainsintact.Tosimplifytheanalysis,themodelassumesthattheoperators preferentiallytransfertohotlegrecirculationusingTrainsAandthenB,never transferringTrainC.TheaccidentsequencekeepstrackoftheRCSloopwith thebreakthoughthisknowledgeisassumednotavailabletotheoperators;i.e.,

themodelallowstheoperatorstoalignanLHSIpumptoabrokenRCSloopin whichcasethattrainisnotassumedtobesuccessfulforhotlegrecirculation.Plantcon"guration(e.g.,impactofdebris,etc.)-Theloadingofdebrisonthesumpstrainershasnoimpactontheactiontoalignforhotlegrecirculation.If theloadingissttocauseanLHSIpumptoloseitsfunction,thenfailure ofallthreesumpsareconservativelyassumedlost,overstatingtheimpactof GSI-191phenomenaintheassessment.Tuesday1 stMarch,2016:19:32,Page123of393 DRAFTPART2.RAIRESPONSES(ROUND1)Whetherthebreakisinthecoldleg-Theproceduralguidanceisnotdepen-dentonthebreaklocationbeinginthecoldorhotlegs.Thesameactionsare taken.TheproceduralcautiontoleaveonetrainofSIalignedtothecoldlegsis alwaysobservednomatterwhattheoperatorsdetermineastothelocationof thebreak.Theextentofcore"owblockagepriortohotlegswitchover-Fortheassess-mentoftheeofGSI-191phenomena,onlyboronprecipitationpriortothe timeofhotlegrecirculationisofinterest.Boronprecipitationafterthetimeof hotlegrecirculationisalreadyconsideredinthebasePRA.Ifthebreakisin thehotleg,boronprecipitationisnotatissue.Ifthebreakisinthecoldleg, andhotlegrecirculationisnotaligned,thenfortheMediumandLargeLOCA breaksizes,boronprecipitationleadingtolossofcorecoolingisalwaysassumed regardlessoftheGSI-191phenomena.

Reference1.SouthTexasProjectHumanReliabilityAnalysisNotebook,STI32746637.2.1.1.18APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6STPResponse:(Item6,Page44)TheoperatoractionsdescribedinSectionC.5.8ofAppendixCtoVolume1areforinadequatereactorcore"owconditions.Theoperatoractionsmodeledin thePRAevaluationofGSI-191phenomenaareinsteadforconditionsinwhich reactorcore"owisadequate.TheGSI-191phenomenaarethenimposedon theseotherwisesuccessfulscenarios.Nocreditisgivenfortheadditionaloperator actionsdiscussedinSectionC.5.8mitigatingthepotentialinadequatereactor core"owconditionsthatmaybecausedbyGSI-191phenomenaasevaluatedin CASAGrande.TheoperatoractionslistedinC.5.8areintendedtodemonstrate thedefenseindepthavailabletodealwithsuchphenomenashouldtheyoccur.TheactionscreditedforMediumandLargebreakLOCAsarepresentedintheeventsequencediagramofAppendixA,FigureA.3.1ofVolume2.The operatoractionsaremodeledintopeventsOR,OS1,OFFS,andHLEG.These arebrie"ydiscussedbelow.TopEventORrepresentstheoperatoractiontomanuallyactuatesafetyinjectionwheneverESFASfailstogenerateasafetyinjectionsignal.Thisaction isrequiredearlyinthescenariofollowingaMediumorLargebreakLOCA

initiator.TopEventOS1representsthemanualactiontosecureonetrainofcontain-mentsprayifallthreeareinitiallyrunning,toconserveRefuelingWaterStorage Tank(RWST)water.Thisactionisunrelatedtothepresenceofdebris.While includedinthePRAeventtreemodel,thestatusofthistopeventisnotconsid-eredinsubsequentevents.Instead,theCASAGrandesimulationaccountsfor thisactionbytheassumedtimesofitsimplementation.TopEventOFFSrepresentsthemanualactiontosecurealltrainsofcontain-mentspraywhenthecontainmentpressurefallsto6.5psigandtheTechnical SupportCenter(TSC)concurs.Thisactionisunrelatedtothepresenceofde-bris.WhileincludedinthePRAeventtreemodel,thestatusofthistopevent isnotconsideredinsubsequentevents.Instead,theCASAGrandesimulationaccountsforthisactionbytheassumedtimesofitsimplementation.ThisactionTuesday1 stMarch,2016:19:32,Page124of393 DRAFTPART2.RAIRESPONSES(ROUND1)isnotexpectedtobeimplementeduntil6.5hoursafteradesignbasisLOCAperOPOP05-EO-EO10.TopEventHLEGrepresentstheactionandequipmentnecessarytoalignatleastonelowheadsafetyinjectiontraintotheassociatedRCShotleg.The operatoractionisnotmodeledasvaryingwiththeamountofdebrisbecauseby procedureitisenteredwhen5.5hourshaveelapsedfollowingthebreak.2.1.1.19APLAB,STPPRAModel-PRAScope:Question1 STPResponse:(Item1,Page44)FragilitycurvesforseismicinitiatedLOCAswerenotdevelopedaspartoftheexistingPRAforSouthTexasProject.SuchLOCAswouldhavetooccur beforetransporttothesumpofdislodgedinsulationwouldbeofconcern.The originalevaluationofseismicfailuresatSTPconcludedthatsuchfailuresofthe RCSwouldhavemedianfailurecapacitiesgreaterthan2.0g;i.e.,seeReference 3.Figure3.6ofReference1presentsgenericfragilitycurvesfortheconditional probabilityofaSmallorMediumsizeLOCAinresponsetoagivenearthquake groundmotion.Morerecently,inReference2,EPRIthencurve"ttheseplots (seeTableH-2ofReference2)toconvertthemtostandardform.Arepresenta-tivefragilitycurveforLargeLOCAsisalsopresentedinReference2.Information fromReference2isprovidedinthetablebelow.LOCASizeMedianAccelerationBeta-rBeta-uHCLPFSmall1.0.3.4.315 Medium.0.35.45.534 Large2.5.3.4.788MostrecentlySTPsubmittedtotheUSNRCitsresponsetotherequestforinformationtoRecommendationTask2.1oftheNear-TermTaskForcein responsetotheFukushimaevent(Reference4).Table2.2.2-1gofReference4 providesanup-to-datemeanfrequencyexceedancecurvefortheseismichazard atSTP.ByconvolutingthishazardcurvewiththeSmall,Medium,andLarge LOCAFragilitiesnotedintheabovetable,thefrequencyofSmall,Medium,and LargeLOCAsinitiatedbyseismiceventsatSTPisfoundtobe4.25X10 7peryearforSmallLOCAs,1.08X10 7peryearforMediumLOCAsand5.06X10 8peryearforLargeLOCAs.Clearlythepotentialforthedislodgementofinsulationbyseismicshakingtobeofconcernisafunctionofthehazardcurveassumed.ForSmallLOCAs, transporttothesumpwouldbeminimalbecausethecontainmentsprayswould notbeinitiated.Forlargerbreaks,whichlikelywouldinitiatecontainmentspray, thefrequencyofsuchseismicallyinitiatedbreaksismuchlower.Becausethein-sulationiscontainedinsidearobustfabriccoveringdesignedforhandling,any insulationthatfailedwouldfallinrelativelylargeclumpswhichwouldbe lesslikelytotransport.Evenassumingnocreditforsumprecirculationfollow-ingaseismicevent,theimpactwouldbeverysmall.Whilenofragilityanalysis hasbeenperformedonpipeinsulationawayfromthebreak,wheresuchin-sulationisassumedtobedislodged,thechancesoftheinsulationfailingand beingtransportedtothesumpmustbesmall.EvenassumingaprobabilityofTuesday1 stMarch,2016:19:32,Page125of393 DRAFTPART2.RAIRESPONSES(ROUND1)0.1thattinsulationisdislodgedandtransportedtothecontainmentsumpstocausesumpplugging,theimpactofrecirculationfailureforMedium andLargeLOCAsinitiatedbyseismiceventswouldthenbeverysmall;i.e.,

0.1(1.08x107+5.06x108)=1.6x108peryear,assuminglatestSTP-speci"cseismichazardmeancurveapplies.

References1.M.P.Bohn,J.A.Lambright,ProceduresfortheExternalEventCoreDam-ageFrequencyAnalysesforNUREG-1150,NUREG/CR-4840,SandiaNational Laboratories,preparedforUSNuclearRegulatoryCommission,November1990.

2.EPRI3002000709,SeismicProbabilisticRiskAssessmentImplementation Guide,FinalReport,December2013,ProjectManagerJ.Sursock.

3.D.A.Wesely,etal.,SeismicFragilitiesofSelectedStructuresandCompo-nentsattheSouthTexasPlant,preparedforPickard,LoweandGarrick,Inc.

byNationalTechnicalSystems,June1987.HL&P1060-DOC-353(c.3),Report No.1628.

4.LetterfromG.T.PowelltoU.S.NRC,SeismicHazardandScreeningReport (CEUSSites),ResponseNRCRequestforInformationPursuantto10CFR50.54(f)

RegardingRecommendation2.1oftheNear-TermTaskForce,ReviewofInsights fromtheFukushimaDai-ichiAccident,NOC-AE-14003114,DatedMarch31, 2014.(ML14099A235)2.1.1.20APLAB,ResultsInterpretation-Quanti"cation:Question 1aSTPResponse:(Item1a,Page45)Thevaluesreportedforandwerecalculatedbyrequantify-ingCDFandLERFassumingtheentireGSI-191phenomenamodelsandthen subtractingthebasecaseCDFandLERFwhichdidnotconsiderGSI-191phe-nomena.Sinceargumentswereprovidedtoshowthatonlythemediumandlarge LOCAinitiatorscouldconceivablycontributeviaconsiderationofGSI-191phe-nomena,therequanti"cationofCDFandLERFwasrestrictedtojustthesetwo initiators.TheandLERFfromotherinitiatorsistoosmalltobeof interest.Thereferencesmentionedtosuccessbranchesandtheexclusionoffailurebranchesreferstothecomputationofthehighestfrequencypumpstatesof interest.Thesepumpstatesweredeterminedforthepurposeofde"ningthe pumpcombinationstatesofmostinteresttoevaluateinCASAGrande.They arenotuseddirectlyincomputingCDFand2.1.1.21APLAB,ResultsInterpretation-Quanti"cation:Question 1bSTPResponse:(Item1b,Page45)ThesameLOCAinitiatingeventfrequenciesandparameteruncertaintydis-tributionswereusedforboththebaselineanddebrismodels.2.1.1.22APLAB,ResultsInterpretation-Quanti"cation:Question 2STPResponse:(Item2,Page45)AppendixAtoVolume2presentstopeventsintheMediumandLargeTuesday1 stMarch,2016:19:32,Page126of393 DRAFTPART2.RAIRESPONSES(ROUND1)LOCAeventtreeset.ThetopeventsrepresentingthesevenfailuremechanismsaredescribedinthelateMediumLOCAeventtree;i.e.,TopEventSUMPcom-binesthefailuremechanismsatthesumpstrainer(i.e.,sumppluggingresulting int"ow,lossofNPSH,pumpcavitationcausedbyairingress,and strainercollapsebyexcessiveloading);TopEventFBLKrepresentsthefailure modesforblockageofthecore(i.e.,excessivepluggingwithinthereactorvessel ofthecoolant"owpathtothecorefueltubes),andTopEventBORONrep-resentsthefailuremodeofexcessiveboronprecipitationttoprevent extendedcorecooling.TopEventFBLKisassignedzeroprobabilityofoccurrenceasaresultoftheCASAGrandeanalysis.Therefore,thesequencesthatresultincoredamage frequencyduetofailureofrecirculationfromGSI-191phenomenaarethose limitedtocaseswheneitherofTopEventsSUMPorBORONfail.Toobtainthetop100sequencesleadingtocoredamagefromonlyGSI-191phenomena,asequencegroupwasde"nedthatrestrictsthesequencesinthe grouptothoseinitiatedbyeitherMediumLOCAorLargeLOCA,whichlead tocoredamageandwhichinvolvefailureofoneofthesplitfractionsfortop eventSUMPorBORON.Thetop100sequencesofthissequencegroupare listedinthefollowingtable.NotethelistofsequencesinVolume2(Table4-7)identi"esexamplesequencesleadingtocoredamageinvolvingMediumand LargeLOCAsandinvolvingGSI-191phenomena.Thattableprovidesadditional insightintothenatureofthescenariosinvolvingGSI-191phenomenathatlead tocoredamage.Foreachsequenceinthegroup,thefollowingispresented:SequenceRankInitiatingEventName InitiatingEventFrequency SplitFractionName SplitFractionFailureProbability TopEvent-SplitFractionDescription EndStateName OverallSequenceFrequency

%ContributiontotheTotalSequenceGroup;i.e.,3.07x10 8peryearNotethatsequencesdependingontheassumedlocationofthebrokenRCSloop,theinitialstatusofmaintenance,thetrainsnormallyrunning,aswell asthespeci"cGSI-191splitfractionwhichisdeterminedbytheECCSpump

state.Thesequencegrouptotalof3.07x10 8peryearisslightlygreaterthantheincreaseincoredamagefrequencyreportedinVolume2,belowTable4-2,as

2.88x108peryear.ThereasonforthisslightincreaseisthatinthemodelincludingGSI-191phenomena,somesequencesarenowassignedtocoredamage becauseofGSI-191phenomenathatwerealreadyassignedtocoredamageinthe basemodelwithoutGSI-191phenomena.Forexample,ifalowfrequencypump stateisoneofthedefaultstates,theassociatedMediumandLargeLOCAs sequencesareassignedtocoredamagebecauseofGSI-191phenomena.Someof thesesequencesarelistedinthetablebelow.AportionofthesesequencesareTuesday1 stMarch,2016:19:32,Page127of393 DRAFTPART2.RAIRESPONSES(ROUND1)alsoassignedtocoredamageinthebasemodelduetolossofbothRHRheatexchangercoolingandcontainmentfancoolercooling.Thesemultiplecausesof coredamageareaccountedforwhensubtractingthetotalstoobtainthechange incoredamagefrequencyduetoGSI-191phenomena.The2.88x10 8peryearvalueisthereforetheappropriatevaluefortheincreaseincoredamagefrequency.Thetop100sequencesleadingtocoredamageduetoGSI-191phenomenaarelistedinthefollowingtable.RankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group1LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA2LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA3LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA4LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page128of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA5LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.37BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPD---TMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA6LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA7LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA8LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA9LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page129of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA10LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA11LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA12LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA13LLOCA5.20E-06Large LOCAMELTBORON3.80E-101.24BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUEScontinuednextpage...Tuesday1 stMarch,2016:19:32,Page130of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group14LLOCA5.20E-06Large LOCAMELTBORON3.80E-101.24BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES15LLOCA5.20E-06Large LOCAMELTBORON3.79E-101.24BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES16LLOCA5.20E-06Large LOCAMELTBORON3.79E-101.23BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES17LLOCA5.20E-06Large LOCAMELTBORON3.79E-101.23BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES18LLOCA5.20E-06Large LOCAMELTBORON3.79E-101.23BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page131of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES19LLOCA5.20E-06Large LOCAMELTBORON3.78E-101.23BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES20LLOCA5.20E-06Large LOCAMELTBORON3.78E-101.23BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES21LLOCA5.20E-06Large LOCAMELTBORON3.78E-101.23BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES22LLOCA5.20E-06Large LOCAMELTBORON3.78E-101.23BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page132of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES23LLOCA5.20E-06Large LOCAMELTBORON3.77E-101.23BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES24LLOCA5.20E-06Large LOCAMELTBORON3.77E-101.23BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES25MLOCA3.05E-04Medium LOCAMELTSUMP8.02E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case3,LH,HH,CS,SICOMSI38BA1.56E-04-SI38PATHB-SI38PATHB-SI38A=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:

CSSTRAINBCSUPPORTAVAIL-

ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES26MLOCA3.05E-04Medium LOCAMELTSUMP8.02E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case3,LH,HH,CS,SICOMSI38BA1.56E-04-SI38PATHB-SI38PATHB-SI38A=Scontinuednextpage...Tuesday1 stMarch,2016:19:32,Page133of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS2AE9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAB:

CSSTRAINABSUPPORTAVAIL-ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES27MLOCA3.05E-04Medium LOCAMELTSUMP8.02E-110.26BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMSI38BA1.56E-04-SI38PATHB-SI38PATHB-SI38A=SPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS2AE9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAB:CSSTRAINABSUPPORTAVAIL-ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES28MLOCA3.05E-04Medium LOCAMELTSUMP7.98E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHA PBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:CSSTRAINACSUPPORTAVAIL-

ABLEcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page134of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupRBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES29MLOCA3.05E-04Medium LOCAMELTSUMP7.97E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHAPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS2AE9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAB:

CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES30MLOCA3.05E-04Medium LOCAMELTSUMP7.97E-110.26BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHAPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:

CSSTRAINACSUPPORTAVAIL-

ABLERBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES31MLOCA3.05E-04Medium LOCAMELTSUMP7.97E-110.26BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHAPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page135of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDCS2AE9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAB:

CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES32MLOCA3.05E-04Medium LOCAMELTSUMP7.95E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB-Case3,LH,HH,CS,SICOMSI38CA1.55E-04-SI38PATHC-SI38PATHC-SI38A=S,SI38B=SPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:

CSSTRAINACSUPPORTAVAIL-ABLERBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES33MLOCA3.05E-04Medium LOCAMELTSUMP7.95E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case3,LH,HH,CS,SICOMSI38CA1.55E-04-SI38PATHC-SI38PATHC-SI38A=S,SI38B=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEEDFAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:CSSTRAINBCSUPPORTAVAIL-ABLEcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page136of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupRAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES34MLOCA3.05E-04Medium LOCAMELTSUMP7.94E-110.26BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case3,LH,HH,CS,SICOMSI38CA1.55E-04-SI38PATHC-SI38PATHC-SI38A=S,SI38B=SPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:

CSSTRAINACSUPPORTAVAIL-

ABLERBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES35MLOCA3.05E-04Medium LOCAMELTSUMP7.94E-110.26BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case3,LH,HH,CS,SICOMSI38CA1.55E-04-SI38PATHC-SI38PATHC-SI38A=S,SI38B=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:

CSSTRAINBCSUPPORTAVAIL-

ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES36MLOCA3.05E-04Medium LOCAMELTSUMP7.86E-110.26BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case3,LH,HH,CS,SICOMcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page137of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSI38BA1.56E-04-SI38PATHB-SI38PATHB-SI38A=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:CSSTRAINBCSUPPORTAVAIL-

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-Case3,LH,HH,CS,SICOMPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS8AC1.31E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:CSSTRAINACSUPPORTAVAIL-

ABLERBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES38MLOCA3.05E-04Medium LOCAMELTSUMP6.74E-110.22BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case3,LH,HH,CS,SICOMPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS8AC1.31E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:

CSSTRAINACSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES45MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABSUPPORTAVAIL-

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CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES48MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page141of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS8AE1.30E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:

CSSTRAINABSUPPORTAVAIL-

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA50LLOCA5.20E-06Large LOCAMELTSUMP6.13E-110.2BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH,RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA51LLOCA5.20E-06Large LOCAMELTSUMP6.13E-110.2BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page142of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA52LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

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CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA55LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB-Case1,EW,CC,DG,CH,RH, RCFCcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page143of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA56LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH,RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA57LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA58LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

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CSSTRAINACSUPPORTAVAIL-

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-TDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA89LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page152of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES90LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES91LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES92LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINScontinuednextpage...Tuesday1 stMarch,2016:19:32,Page153of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES93LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES94LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES95LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUEScontinuednextpage...Tuesday1 stMarch,2016:19:32,Page154of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group96LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES97LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES98LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES99LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH, RCFC,CVAcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page155of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES100LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUESTotalQuanti"edFrequencyofSequenceGroup=3.0705E-0082.1.1.23APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion2STPResponse:(Item2,Page46)Thechoiceofgeometricmeanvaluesfromtheexpertelicitationwasthemodelthatmostcloselyfollowstherisk-informedmethodologyinwhichparam-etersandmodelsthatrepresentrealisticbehaviorareselected,asopposedto thosethatwouldbeselectedinothersettingssuchasadeterministicframework inwhichthemostpessimisticmodelswouldbeselected.Thetechnicaljusti"ca-tionisprovidedinthewhitepaperincludedasEnclosure2whereitisshown howthearithmeticmeanemphasizesextremevaluesintheLOCAfrequency

setting.Furtherjusti"cationisprovidedinNUREG1829whereitisrecommendedthattheselectionofthefrequencymodelshouldbeappropriatefortheappli-cation(pagexxii)andwhereitisnotedthatalternativeaggregationmethods canleadtosigni"cantlytresults.TheauthorsofNUREG1829goon tosaythataparticularsetofLOCAfrequencyestimatesisnotgenericallyrec-ommendedforallrisk-informedapplicationsandthatthepurposesandcontext oftheapplicationmustbeconsideredwhendeterminingtheappropriatenessof anysetofelicitationresults.BecausethemaximumamountofdebriswouldbeTuesday1 stMarch,2016:19:32,Page156of393 DRAFTPART2.RAIRESPONSES(ROUND1)createdinthelargesthypothesizedLOCAcategories,itisparticularlyappro-priatethattherisk-informedapproachadoptthemodelthatwouldproducethe mostlikelycenterfrequencies(andconcomitantuncertainty).2.1.2ESGBResponses 2.1.2.1ESGB,ChemicalQuestion12 STPResponse:(Item12,Page56)Inthe30-dayCHLEtestsconductedpriortothelicensesubmittal,noalu-minumprecipitationwasobserved,asevidencedbyaluminumconcentrations thatremainedbelowpredictedsolubilitylimitsandnoobservedincreaseintur-biditythatwouldhavebeenindicativeofaprecipitateinsolution.Without directevidenceofaluminumprecipitation,itwasnotpossibletorelatethehead losscharacteristicsofthe30-dayCHLEteststochemicalAsdescribedin theLAREnclosure4-1,page9andinmoredetailinLAREnclosure4-3,Section 5.6.3,safetymarginwasaddedtothechemicalcontributiontoheadloss byapplyingabump-upfactortothecalculatedvalueofconventionalheadloss basedonknownphysicallyrelevantparametersofdebrisbedthicknessandsump "uidtemperature.Thechemicalheadlossbump-upfactordidnotdirectlyuse headlossdatafromtheCHLEtests.Asaresult,variabilitybetweenthethree headlosscolumnshasnobearingontheSTPlicensesubmittal.Althoughpotentialbiasbetweenthethreeheadlossloopshasnoonthelicensesubmittal,STPrecognizesthatitisapilotprojectandthatbiasesin experimentalequipmentmayfuturelicensees.Apossiblebiaswasobserved intwotestseriespriortotheSTPlicensesubmittalwhenthethreecolumnswere linkedtothetank.ThereportsofthesetestserieswereprovidedtotheNRC inSTPLetterNOC-AE-14003075(1).First,inCHLE-008(2),preformed WCAPprecipitateswereintroducedintothetankwhilethetankwasconnected tothecolumns.Onetestwasconductedwithblender-prepareddebrisbedsin allthreecolumnsandasecondtestwasconductedwithNEI-prepareddebris bedsinallthreecolumns.Inbothcases,theheadlossinColumn3increased20 to30minutessoonerthaninColumns1and2.Second,inCHLE-010(3),head lossincreasedondttrendsinthethreecolumnsafterthecolumns(all containingblender-prepareddebrisbeds)werelinkedtothetank,withthehead lossinColumn3dramaticallyhigherthantheothercolumns.This inheadlossoccurreddespitethefactthatnocorrosionmaterials,debris,or precipitationproductswerepresentinthetank.FollowingtheSTPlicensesubmittal,thecontractor,UNM,hasexploredpos-siblecausesforthebiasesobservedinCHLE-008andCHLE-010(2,3).Afactor thatmayhavecontributedtothepotentialbiaswasthepipeheadercon"gu-rationthatsuppliedwaterfromthetanktothethreecolumns.Thecolumns werelocatedonacommonheader,withColumn3beingthelastcolumnonthe header.Thetanksystemwasrecon"guredaftertheSTPlicensesubmittalso thateachcolumnissupplieddirectlyfromthetankwithoutthepresenceofa commonheader.ArepeatofthetestinCHLE-008(2)hasnotyetbeencon-ductedtoascertainwhetheranychangeinperformancehasresultedfromthe pipingmodi"cation.ItshouldbenotedthatothertestswereperformedinwhichnosystematicTuesday1 stMarch,2016:19:32,Page157of393 DRAFTPART2.RAIRESPONSES(ROUND1)biaswasobserved.ThetrendinheadlossintheMBLOCAtest,CHLE-012(4)wassimilarinallthreecolumns,whichcontainedNEI-prepareddebrisbeds.

IntheLBLOCAtest,CHLE-014(5),alsowithNEI-prepareddebrisbeds,the headlossinColumn3wasbetweenthevaluesforColumns1and2.Thebias hasonlybeenobservedwhenblender-prepareddebrisbedswereused.Other testsreportedinCHLE-008(2)demonstratedahighdegreeofinconsistency andinstabilityinblender-prepareddebrisbeds.Theinstabilityoftheblender-prepareddebrisbedscauseslargeincreasesinheadlossfromsmallchangesin particulateconcentration,regardlessofwhetheritisnon-chemicalorchemical precipitate.Theresultsindicatethatthevariabilitybetweencolumnsisampli-

"edsigni"cantlyfortheblender-prepareddebrisbedsandnotevidentforthe NEI-prepareddebrisbeds.Tominimizethisedebrisbedsthataremore prototypicaloftheconditionsduringaLOCAarebeingstudiedatUNM.More prototypicaldebrisbedsaresensitivetothepresenceofprecipitates,butare substantiallymorestablethantheblender-prepareddebrisbed.Moreproto-typicalbedsconsistof"berpreparedwiththeNEIpressure-washingmethod supplementedwitheitherpaintparticlesorlatentdebrisandpaintparticles.

Recenttestshavedemonstratedahighdegreeofstability,reproducibilitybe-tweenreplicatetestsinthesamecolumn,andreproducibilitybetweensimilar bedsintcolumns.Worktocharacterizetheheadlossofthebedsand documentthesuitabilityofthesebedsforfuturechemicalheadlosstestingis currentlyongoing.Informationgainedduringtestingafterthelicenseapplica-tionhasnotchangedtheconclusionsoftheanalysisconductedforthelicense application,andSTPisnotplanninganyadditionalchemicaltestingin supportofthelicenseapplication.

REFERENCES:

1.SouthTexasNuclearOperatingCompany,LettertotheNuclearRegula-toryCommission,NOC-AE-14003075.Feb.27,2014.(ML14072A076)2.UniversityofNewMexico,CHLE-008:DebrisBedPreparationandFor-mationTestResults,Rev.4.Feb.3,2014.(ML14072A082)3.UniversityofNewMexico,CHLE-010:CHLETankTestResultsforBlendedandNEIFiberBedsWithAluminumAddition,Rev.3.Feb.10,2014.(ML14072A083)4.UniversityofNewMexico,CHLE-012:T1MBLOCATestReport,Rev.4.Feb.18,2014.(ML14072A084)5.UniversityofNewMexico,CHLE-014:T2LBLOCATestReport,Rev.3.Feb.22,2014.(ML14072A085)2.1.2.2ESGB,ChemicalQuestion13a STPResponse:(Item13a,Page56)ThealuminummaterialusedintheCHLEtestswasapieceofscaf-foldpickboards(notthepoles)fromtheSTPplant.Theswas typicalsthathadbeeninuseattheplantforseveralyears.Thispiece ofwaschosenbecauseitwastypicalofstoredincontain-ment.Sincontainmentissimilartotheusedconditionofthetested materialbecausesarereusedoverandoveragaininthecontaminated, highradiationareastoavoidspreadingcontaminationandadditionalpersonnel exposurefrommovingtheminandout.Notethatafractionofthesurfacearea ofthetestedmaterial(theedges)wasnotoxidizedbecausethepieceshadtobeTuesday1 stMarch,2016:19:32,Page158of393 DRAFTPART2.RAIRESPONSES(ROUND1)cutinordertoobtainthecorrectareaexposed,whichwouldberepresentativeofdamagetopre-existingscalesurfacesonincontainment.Toprevent anychangetothesurfaceconditionsofthetheonlypreparationin thelabwastocleanthesamplegentlywithmildlaboratorysoaptoremove particulateandallowtodry.2.1.2.3ESGB,ChemicalQuestion13bSTPResponse:(Item13b,Page56)Thecorrosionbehavioroftpartsoftheswasnotcomparedinbenchcorrosiontests.However,othertestingwasperformedthatindicated similarsurfaceconditions,whichwouldbeexpectedtoproducesimilarcorro-sioncharacteristics.Surfaceconditionsweredeterminedusingscanningelectron microscopy(SEM)withenergydispersivespectrometry(EDS)andX-raypho-toelectronspectrometry(XPS).TheSEMimagesinFigure1showthatthe surfaceofportionsoftheusedforsubmergedandvaporspacecondi-tionswerequalitativelysimilaratamicroscopiclevel(1).TheEDSdatashown inTable1alsoshowqualitativesimilaritiesbetweentheportionsofs ing,inthatthesurfaceelementalcompositionisdominatedbyaluminumand oxygen,withsmallamountsofotherelements.TheXPSspectrainFigure2 demonstratesthatbothportionsofshavesurfacelayersconsisting ofaluminumphosphate(AlPO 4)andaluminumoxide/hydroxide[AlOOHor Al(OH)3,whichhaveoverlapping2pspectra].Inbothcases,thesurfacelayersweredeterminedtobeabout90percentAlPO 4and10percentAlOOH/Al(OH) 3(2).Giventhesimilaritiesinsurfaceconditions,incorrosionbehavior arenotexpected.(A)(B)Figure1:Scanningelectronmicroscopeimagesofstobeusedin(A)sub-mergedconditionsand(B)vaporspaceconditions.TheseimageswerecollectedfrompiecesofthatwerenotusedinthecorrosiontestsandrepresenttheconditionasreceivedfromSTP.2.1.2.4ESGB,ChemicalQuestion13cSTPResponse:(Item13c,Page56)ThesurfaceconditionoftheshasnotbeenexposedtoaLOCAjettodetermineiftheoxidewouldspallandresultinagreatercorrosionrate thanobservedduringtheCHLEtesting.Someisstoredintworacks onthecontainment19insidethebioshieldwall(perTechnicalSpeci"cationTuesday1 stMarch,2016:19:32,Page159of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2.1:Elementalcompositionoftobeusedin(A)submergedconditionsand(B)vaporspaceconditions.Thisdatawascollectedfrompiecesofthat werenotusedinthecorrosiontestsandrepresenttheconditionasreceivedfromSTP.ElementPercentmassonscaf-foldingtobeusedin submergedconditionsPercentmassonscaf-foldingtobeusedinva-porspaceconditionsO37.429.1 Na1.30.5 Al49.858.7 Si5.25.1 P3.41.7 Ca0.40.9 S2.5-Cl-0.3 K-1.3 Fe-1.6 Mg-0.6 Zn--(A)(B)Figure2:X-rayphotoelectronAl2pspectraoftobeusedin(A)submergedconditionsand(B)vaporspaceconditions.Thesedatawerecollectedfrompiecesof thatwerenotusedinthecorrosiontestsandrepresenttheconditionas receivedfromSTP.Surveillanceprocedure0PSP03-XC-0002andplantgeneralprocedure0PGP03-ZM-0028),whichisanareawhereitcouldbepartiallyexposedtojettingfrom ahypothesizedfailureproducingajetthatisdirectedtowardthestorageracks.

Thesistightlypackedintoseismically-quali"edstorageracksand, althoughtheracksareopenonthesides,onesideisprotectedbyaconcrete wall,theyareconstructedwithstructuralsteelI-beams,andclosedontheends withstructuralsteeldoorstokeepstoredmaterialfrombeingreleasedduring aseismicevent.Thetightpacking,concretewalls,andstructuralmaterialall serveasbarriersthatlimitexposuretojets.Finally,energeticjetshypothesized toresultfromaLOCAareshortduration(minutes)comparedtocorrosiontimeTuesday1 stMarch,2016:19:32,Page160of393 DRAFTPART2.RAIRESPONSES(ROUND1)scales(hours).Afterthejetdiesdown,thematerialisnolongerexposedtopost-LOCA"uidimpingement.Inaddition,all(100%ofthesurfacearea)ofthe aluminummaterialisconsideredexposedtocontainmentsprayeventhoughitis tightlypackedinthestorageracks.Thisconservativeassumptionisconsideredto outweighanyconsiderationofpotentialincreasedcorrosionofalimitedportion ofthealuminumduetoremovalofanoxidelayerbyimpingement.2.1.2.5ESGB,ChemicalQuestion19 STPResponse:(Item19,Page58)Yes,thetermarti"cialinthecaptionofFigure5.6.6referstotheheadlossin"ationfactordistributionof5

+/-1thatisrandomlysampledandappliedtotheNUREG/CR-6224resultforconventionaldebrisheadloss.2.1.3SRXBResponses 2.1.3.1SRXB,Question1 STPResponse:(Item1d,Page65)TheresponsetoSRXBRAI1wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.2SRXB,Question2 STPResponse:(Item2e,Page65)TheresponsetoSRXBRAI2wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.3SRXB,Question3 STPResponse:(Item3,Page65)TheresponsetoSRXBRAI3wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.4SRXB,Question4 STPResponse:(Item4,Page65)TheresponsetoSRXBRAI4wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.5SRXB,Question5a STPResponse:(Item5a,Page65)TheresultsshowninTable2.2.1wereobtainedfromthesimulationsofLOCAscenariosoftbreaksizesperformedwiththeRELAP5-3DandMELCOR inputmodels.Adetaileddescriptionofthesimulationconditionsisreportedin

[1].ThevolumeofthewaterintheRWSTde"nedintheRELAP5-3Dinput modelwasde"nedinaccordancewiththeplantemergencyoperationprocedures 0POP05-EO-EO10step22[2]whichinstructtheoperatortoinitiatethesump switchoverprocedurewhenRWSTlevelislessthan75,000gallons,whichiswhen thelow-lowlevelalarmisactuated.Table1liststheRWSTvolumesofwaterat talarmlevels.TheInjectionwascalculatedasfollow:Max.(Min.)UsableVolume=High-Alarm(LowAlarm)VolumeEmptyVolumeTuesday1 stMarch,2016:19:32,Page161of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2:RWSTVolumesLevelVolume(gal)HighAlarm(Nominal)528,000LowAlarm(Nominal)473,000 Low-LowAlarm(Nominal)75,000 EmptyVolume(Nominal)32,000 MaxUsableVolume496,000 MinUsableVolume441,000 AverageUsableVolume468,500 UsableVolume(LOCA)456,735InjectionVolume(LOCA)413,735AverageUsableVolume=(MaxUsableVolume+MinUsableVolume)/2InjectionVolume=AverageUsableVolume(Low-LowAlarmVolumeEmptyVolume)TheInjectionVolumede"nedintheRELAP5-3Dinputmodelisequalto413,735USgal.2.1.3.6SRXB,Question5bSTPResponse:(Item5b,Page65)Table2showstheECCS"owrateandtheCSS"owrateforthebreaksizesreportedonTable2.2.1.Table3:FlowratesandsumpswitchovertimeBreaksize1.5246815DEGSumpSwitchoverTime5.6h1.3h5.6h55.9m44.2m37.8m29.5mTotalSIFlowRate(gpm)1230.72075.84119.67950.710285.411779.711988.2 TotalCSFlowRate(gpm)0.0 15200.05200.05200.05200.05200.05200.0 1Simulationresultsshowedthatthecontainmentspraysdidnotactuatefora1.5break.Thecontainmentspraysvolumetric"owrateimposedintheMELCORinputmodelwascalculatedunderthefollowingassumptions:

• The"owrateforeachCSpumpwasimposedtobeequalto2600gpm(correspondingtothemaximumsingletrain"owrate)

• Oneofthethreecontainmentspraypumpsmanuallysecuredatthebe-ginningofthetransient[2].2.1.3.7SRXB,Question5cSTPResponse:(Item5c,Page65)Thesumpswitchovertimewascalculatedviaacontrolvariablede"nedintheRELAP5-3Dinput"leasthetimerequiredtodepletetheRWSTinjection volumeof413,735USgal.Detailsofthecontrolvariablelogicadoptedarelisted below:Tuesday1 stMarch,2016:19:32,Page162of393 DRAFTPART2.RAIRESPONSES(ROUND1)1)Acontrolvariablewasde"nedtocalculatethetotalECCS"owrateasthesumofthe"owrateofalltheactivesafetyinjectionpumps(calculatedby theRELAP5-3Dsimulation)andcontainmentspraypumps(calculatedby theMELCORsimulation).2)Anintegralcontrolvariablewasde"nedintheRELAP5-3DinputdecktocalculatethetotalvolumeofwaterwithdrawnfromtheRWST,asthe timeintegralofthetotal"owratedescribedin1).totalinjectedvolume

=t=t t=0 s (total"owrate

)dt3)Thesumpswitchovertimewascalculatedasthetimetatwhichthetotalinjectedvolumecalculatedin2)reachestheRWSTinjectionvolume.2.1.3.8SRXB,Question6STPResponse:(Item6,Page65)Figure1showsthecontainmentpressurevs.timeestimatedusingMELCORfortherangeoftherangeofbreaksizesreportedinTable2.2.1,underthe nominaloperatingconditions[1]:

• NumberofoperatingSItrains=3

• NumberofContainmentSprays=2(onepumpsecuredbymanualproce-dure[2]*Numberoffancoolers=6

• CCWTemperature=85.84FThesprayactuationsetpoint(9.5psig)andthespraysterminationsetpoint(6.5psig)arealsoplottedinthe"gure.2.1.3.9SRXB,Question7aSTPResponse:(Item7a,Page66)TheinstructionsfortransferringtheSafetyInjectionSystemtohotlegre-circulationareprovidedintheEmergencyOperatorProcedure0POP05-EO-ES14TransfertoHotLegRecirculation.Thisprocedureisenteredfromthe 0POP05-EO-EO10LossofReactororSecondaryCoolantStep28,when5.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />shaveelapsed.Theactionsfollowedbytheoperatorduringthisprocedurearesummarizedinthetablebelow.2.1.3.10SRXB,Question7bSTPResponse:(Item7b,Page66)ThetableintheresponsetoRAI7aaboveshowstheestimatedtimerequiredtoperformthemanualoperationstocompletethehotlegswitchoverprocedure

[3].Thetimerequiredtocompleteeachoperationdescribedinthetablewere takenfromthegeneraloperatoractiontransittimesandequipmentmanipula-tiontimesfromEOPT-05.01[4]measuredforEmergencyOperatorProcedures localsteptiming.Theseactionsarenottimedinthesimulator.Tuesday1 stMarch,2016:19:32,Page163of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:ContainmentPressureAsspeci"edintheSTPplantemergencyprocedure[3],onlytwoofthethreeSItrainsareswitchedtohotlegrecirculation.Undertheseconditions,thetotal "eldtimerequiredtotransfertheSItrains(two)tohotlegrecirculationis4.5 min.Notethatthisisthelocaloperator"eldtimeandsomeadditionaltimeover the"eldtimeisrequiredtocompletetheotherstepsthatareperformedinthe controlroom.Theadditionaltimerequiredwouldbetomanipulatethecontrol handswitchesandperformthestepexecution(three-waycommunicationand veri"cation,etc.)However,sincetheothermanipulationsareinthecontrolroom onthesamecontrolpanel,15minuteswouldbeadequatetimetocompletethe evolution.2.1.3.11SRXB,Question8 STPResponse:(Item8,Page66)ThevaluesofthetotalSafetyInjection(SI)volumetric"owratesshownintable2.2.14representthevolumetric"owrateatthesumpswitchovertimefor tbreaksizes,calculatedwiththethermal-hydraulicsimulations,assum-ingthatalltheSIpumps(HHSI,LHSI,threeSItrains)areavailableduring thesimulation.AllSIpumpsoperatingisde"nedasthenominaloperatingcon-dition.Foranyothergivenscenario,thevolumetric"owrateforindividualSI pumpswasestimatedbasedontheratioofthemaximumpumpcapacities,using Equations4and5(Volume3,page53of248).NominalSIoperatingconditionsareareasonablesurrogateforallplant-statecon"gurationsbecause:(1)nominalconditionsareexpectedforalmost95%of allLOCAaccidentscenarios,and(2)plantcon"gurationsthatincludefailed SIpumpsdrawwatertothesumpatafarlowerratethanthesmallincrease experiencedfromrelaxationofbackpressureontheRCSbythelossof oneormoreSIpumps.2.1.3.12SRXB,Question9 STPResponse:(Item9,Page66)Tuesday1 stMarch,2016:19:32,Page164of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:Switchovertohotleg:SummaryoftheprocedureSTPResponse:

• TheTotalSIFlowRateisthe"owrateforcedbytheHHSIandLHSIofthethreeSItrains.TotalSIFlowRate=(HHSI"owrate+LHSI"owrate)

• TheTotalECCSFlowRateisthesumoftheTotalSI"owrateandtheContainmentSprays(CS)FlowRate.TotalECCSFlowRate=HHSI"owrate+LHSI"owrate+CS"owrate

• TheTotalSumpFlowRateisthetotal"owthroughthesumpstrainers.Thevalueofthetotalsump"owrateatanytimeisequaltotheTotal ECCSFlowRate:TotalSumpFlowRate=TotalECCSFlowRateTuesday1 stMarch,2016:19:32,Page165of393 DRAFTPART2.RAIRESPONSES(ROUND1)

References:

[1].TexasA&MUniversity,SumpTemperatureSensitivityAnalysisRevi-sion2.0.January2013[2].SouthTexasProjectElectricGenerationStation,LossofReactororSecondaryCoolant.DepartmentProcedureSafetyRelated(Q),0POP05-EO-EO10Rev.20(2011)[3].SouthTexasProjectElectricGenerationStation,TransfertoHotLegRecirculationDepartmentProcedureSafetyRelated(Q),0POP05-EO-ES14 Rev.7(2008).[4].SouthTexasProjectElectricGenerationStation,EOPLocalAction.GeneralOperatorActionTransitTimesEOPT-05.01Rev.5.2.1.4SSIBResponses 2.1.4.1SSIB,ZOI:Question1 STPResponse:(Item1,Page66)TheDEGBvaluescomputedbyEquation22ofLAREncl.4-3(Page125,Section5.3.1)areextraneousinformationandwerenotusedintheanalysis.

Table5.3.1(LAREncl.4-3,Pg.126)includesdatarepresentingthenominal pipesize,actualpipesizeandanunusedextrapolationtoaDEGBsizede"ned byEquation22foreachweldcategory.TheseunusedCADcalculatedDEGB sizeswerealsoapparentinTable5.3.2(LAREncl.4-3,Pg.128).Thepipe scheduleandouterdiameterde"neactualpipesize,synonymoustoitsinner diameterwithinLAREncl.4-3.CASAGrandeanalysisutilizesactualpipesize forallcalculations,includingZOIdetermination.AnactiontoremovetheunusedinformationhasbeenenteredintheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.2.1.4.2SSIB,DebrisCharacteristics:Question2 STPResponse:(Item2,Page66)ThesizedistributionsforNukonandThermalWrapdebriscreatedbythepostulatedLOCAjet(%ofeachsizecategorycreated)areaslistedbelow.These valuesarecontainedinreference46,Table4.1(LAREncl.4-3).NukonandThermalWrapareanalyzedaslowdensity"berglass(LDFG)andhavethesamedebrissizedistributionandZOIs.ThemethodologyNEI04-07Vol.2,reference45,wasusedtodeterminethesizedistributionsandisbasedonair-jetimpingementtests(AJIT).Thedistributionisbasedonthedistanceoftheinsulationfromthebreakandthecorrespondingimpactpressurewitnessedatthetarget.2.1.4.3SSIB,Transport:Question5 STPResponse:(Item5,Page67)Assumption6.h.Vstatesthatallthreestrainersareactiveduringpool"lltransport.Eachsump,regardlessofservicestate,willcollectaquantityof"nes duringpool"llaslistedinTable5.5.3.Tuesday1 stMarch,2016:19:32,Page166of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.4.4SSIB,Transport:Question9STPResponse:(Item9,Page69)Yes,theevaluationincludesthe1.8%as"nedebris.Alleroded"ber(regardlessoforigin)andall"nesandsmall"bersthat havenotsettledaretreatedidenticallyassuspendabledebris.Figure5.5.3of LAREncl.4-3showsthat37.4%ofsmallpiecesgeneratedintheZOIwillbein-troducedtothepoolassuspendedmaterialthateventuallyreachesthestrainer.DebristransportequationsandthedebristransportlogicdiagramsprovidedintheLAREncl.4-3,Section5.5.7describesthetotalamountofsuspendable debristhatisintroducedtothepoolfromeachlowdensity"berglass(LDFG) sizecategory.AllLDFGthatarrivesinthepooliseither(1)treatedassuspended foreventualtransporttothestrainer,(2)sequesteredininactivecavities,(3) applieddirectlytothestrainersduringpool"ll,or(4)settledonthe"oor.ErosionoflargeLDFGpiecescontributestransportabledebristothepool.ErosionofsettledsmallLDFGpiecesinto"nesalsocontributestransportable debristothepool.Onceintroducedtothepool,thesizecategoryoforigindoes nottotaltransportbecausenofurthercreditisappliedforsettling.2.1.4.5SSIB,Transport:Question11a STPResponse:(Item11a,Page69)Thetermx(t)describesthetime-dependentmassofdebrisinthepoolwithanexponentialdecayfunction.Aswritten,thetermx(t)(LAR.Encl.4-3,Equa-tion41,totheJune19,2013applicationML131750250)shouldbedisregarded.ItwastakenoutofLAREncl.4-3(currentlicensingapplication)becauseitwasnotimplementedinCASAGrandeinthisform.CASAGrandetracks eachindividualdebristypewithsolutionstoEquation84(LAREncl.4-3,Pg.

209),whichdescribesthedtialrateofchangeofdebrismasssuspended inthepool.Thedebrisrecirculationtimeisaccuratelyde"nedbytheratioof poolvolume(m3)tototalvolumetric"owrate(m3/s),whichcanchangeasa functionoftimeifpumpsareturnedThex(t)discrepancyhasbeenaddedtotheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.2.1.4.6SSIB,Transport:Question11b STPResponse:(Item11b,Page70)Thetermx(t)wasnotimplementedintoCASAGrandeintheformdiscussedinLAREncl.4-3(June19,2013applicationML131750250,Equation41).The debrisrecirculationtimeisaccuratelyde"nedbytheratioofpoolvolume(m3) tototalvolumetric"owrate(m3/s).Equation84ofLAREncl.4-3(currentapplication,Pg.209)tracksallpar-ticulateand"brousdebristypesthatcanbesuspendedinthepoolassuming ahomogenouslymixedpool.Thisincludesallcoatings(Quali"edandUnqual-i"ed),allotherparticulates,andall"brousinsulationdebristypesinsideofTuesday1 stMarch,2016:19:32,Page167of393 DRAFTPART2.RAIRESPONSES(ROUND1)containmenthavingsizesclassi"edas"nesorsmallpieces.Anerosionfractionisappliedtolargepiecestogenerateadditionalsuspended"ber.Thesizesofall debristypesevaluatedarelistedinTable2.2.21ofLAREncl.4-3(Pg.57).The samedebrisrecirculationtimeappliestoallsuspendeddebris.Equation84ofLAREncl.4-3(currentapplication,Pg.209),onlyappliestothosequantitiesthatarriveonthestrainerduringrecirculation.Thosematerials thatareinitiallytransportedtothestrainer(earlyarrival)asaresultofpool "llandsheeting"owarenotdependentontheratioofpoolvolume(V)to totalrecirculationpump"ow(Q),butrather,areplaceddirectlyontheactive strainersatinitiationoftheLOCA.Theirmasshoweverisaccountedforand trackedinthetotalinventoryduringthescenario.2.1.4.7SSIB,Transport:Question11c STPResponse:(Item11c,Page70)Equation84ofLAREncl.4-3(currentapplication,Pg.209)usedtotrackpooldebrisinventoryassumeshomogeneousmixinginthepoolofsuspended

debris.Thisassumptionisvalidforallsuspendeddebristypesforthefollowing reasons:1.Forallbreaks,theinitialhigh"oorvelocitiesfromsheeting"owcausedbythepipebreakandcontainmentspraysareexpectedtoscatterdebriswith nopreferentialdirectionthroughoutcontainment.2.Finedebriswillbefurthermixedafterrecirculationbecauseofmultidi-rectionalvelocityvectorsandturbulentkineticenergy.Asanaddedconservatism,solutionstothepooltransportequation(LAREncl.4-3,Section5.8,Equation84)donottakecreditforsettlingofdebrisin thepool.ThismeansthatallsuspendeddebrisisrecirculatedthroughtheECCS backintothepooluntil100%iseventuallytrappedatthestrainersoronthe reactorcore.CFDresultsforsteadystate,isothermalrecirculationareshown below.CFDrepresentationsof"owvectorsforanear-sumpandfar-sumplargeLOCAbreaksaredescribedinthe"gures.Inthenear-sumpbreaksimulation (Case1)abreakontheLoopCHotLegwasmodeled,anditwasassumedthat onlytwotrainswereoperable(LAREncl.4-3,Ref.[23],Figure5.8.1Pg.74).

Themulti-directionalvelocityvectorsthroughoutcontainmentduringsteady-staterecirculationareindicativeofhomogenousmixing.2.1.4.8SSIB,Transport:Question11d STPResponse:(Item11d,Page70)Thex(t)functionisnotinLAREncl.4-3andisnotusedinCASAGrande.Theoriginalformulaforx(t)describesthemassofdebrisinthepoolratherthan themassofdebrisonthestrainer,whichexplainsthenon-intuitiveinterpreta-

tion.2.1.4.9SSIB,Transport:Question11e STPResponse:(Item11e,Page70)Thex(t)functionanditsassociateddebrisdepletionrateisnotinLAREncl.4-3andisnotusedinCASAGrande.ThedepletionrateofsuspendedpoolTuesday1 stMarch,2016:19:32,Page168of393 DRAFTPART2.RAIRESPONSES(ROUND1)debrisimplementedinCASAGrandeisbasedon"ber"ltrationandsheddingratesobtainedfromstrainermoduletesting.100%of"berreachingthecoreis permanentlyretained.?2.1.4.10SSIB,Transport:Question13 STPResponse:(Item13,Page70)Microthermisassumedtofailas100%"nesandistreatedassuchintheSTPevaluation.ThediscrepancyinVolume6.2hasbeenenteredintheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.Inthesecondbreaksimulation(Case2)abreakontheLoopCSIPumpDischargeLinewasmodeledassumingthatonlytwotrainswereoperable(LAREncl.4-3,Ref.

[23],Figure5.8.17Pg.91).Thelocationofthe(Case2)breakisshownbelowinFigure 5.8.17.Themulti-directionalvelocityvectorsthroughoutcontainmentduringsteady-staterecirculationareindicativeofhomogenousmixing.Figure5.8.25showssimilarresultstothoseofFigure5.8.11andcon"rmingthattheTKEafterrecirculationislargeenoughtokeep"ber"neshomoge-neouslymixedthroughoutthecontainmentpool.ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.12Pg.86)for"necoatingschipsareshownin"gure5.8.12.Contoursinyellowshowtur-bulentkineticenergy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page169of393 DRAFTPART2.RAIRESPONSES(ROUND1)ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.20Pg.81)forsmallpiecesof"berglassareshowninFigure5.8.7.Contoursinredshowregionswithtumblingvelocitieslargeenough(0.12ft/s)totumblesunkensmall"berglassdebrisalongthe"oor,whilecontoursinblueareregionswithvelocitiesbelowthistumbling velocity(LAREncl.4-3,Ref.[65]).Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(0.034ft 2/s 2)tokeepsmall"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page170of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.7showsthatforanear-sumpbreak(Case1),thereisnota"owpathtothestrainerthathasTKElargeenoughtosuspendsettlingofsmallpiecesof"berglass.

Thereforetheassumptionthatsmalldebrisishomogenouslymixedinthepoolwithout settlingwhencalculatingthesolutionsofEquation84(LAREncl.4-3,Pg.209)isvalid.

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.20,Pg.94)for smallpiecesof"berglassareshownin"gure5.8.20.Contoursinred,showregionswith tumblingvelocitieslargeenough(0.12ft/s)totumblesunkensmall"berglassdebrisalongthe"oor,whilecontoursinblueareregionswithvelocitiesbelowthistumbling velocity(LAREncl.4-3,Ref.[65]).Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(0.034ft 2/s 2)tokeepsmall"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page171of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.20showsthatforafar-sumpbreak(Case2)thereisno"owpathtothestrainerthathasTKElargeenoughtosuspendsettlingsmallpiecesof"berglass.

ThisisconsistentwiththeresultsofFigure5.8.7,andcon"rmstheassumptionthat smalldebriscanbetreatedashomogeneouslymixedinthepoolwithoutsettlingwhen calculatingthesolutionsofEquation84(LAREncl.4-3,Pg.209).

ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.11Pg.85)for"ber "nesareshownbelowin"gure5.8.11.Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(8.2E-6ft2/s2)tokeep"ne"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page172of393 DRAFTPART2.RAIRESPONSES(ROUND1)Afterrecirculation(Figure5.8.11)"berandcoatings"nesarelikelytomixmoreevenlythroughoutthepoolduetothewidespreadregionsofTKElargeenoughtosuspend andmixthese"nes(LAREncl.4-3,Ref.[23],Figure5.8.11,Pg.85).

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.25Pg.99)for"ber "nesareshownin"gure5.8.25.Contoursinyellowshowturbulentkineticenergy(TKE) greatenough(8.2E-6ft 2/s 2)tokeep"ne"berglassdebrisinsuspension(LAREncl.43,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page173of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.25showssimilarresultstothoseofFigure5.8.11andcon"rmingthattheTKEafterrecirculationislargeenoughtokeep"ber"neshomogeneouslymixedthroughout thecontainmentpool.

ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.12Pg.86)for"necoatingschipsareshownin"gure5.8.12.Contoursinyellowshowturbulentkineticenergy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page174of393 DRAFTPART2.RAIRESPONSES(ROUND1)Afterrecirculation"nechipswouldbelikelytomixevenlythroughoutthepoolbecauseofthelargeregionsofTKEarelargeenoughtosuspendandmixthese"nes(LAREncl.

43,Ref.[23],Figure5.8.12,Pg.86).

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.26Pg.100)for"necoatingschipsareshownin"gure5.8.26.Contoursinyellowshowturbulentkinetic energy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page175of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThedatashowninFigure5.8.26con"rmsthediscussionforFigure5.8.12thatcoating"neswillmixhomogeneouslythroughoutthepoolbecauseoftheirlowTKEsuspension

limit.

TheCFDresultsforthesmalland"nedebrisshowthathomogenousmixingisapplicable forthesedebrissizes.Largedebrissuchasintactblanketsofinsulationandlargepieces werefoundnottotransportunderSTPconditions(LAREncl.4-3,Ref.[23]).Tuesday1 stMarch,2016:19:32,Page176of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.4.11SSIB,NPSHandDegasi"cation:Question29STPResponse:(Item29,Page77)WithinCASAGrande,NPSHriscorrectedforthevoidfractionatthepumpinletinaccordancewithRG1.82,Revision4.Additionally,asdescribedinAs-sumption8.i,(LAREncl.4-3)thevoidfractionatthepumpsisconservatively assumedtobethesameasthevoidfractionatthestrainer,i.e.nocreditistaken forbubblecollapse.2.1.5STSBResponses 2.1.5.1STSB:Question1 STPResponse:(Item1,Page81)TheRAIsaredirectedtowardtheapplicationoftheSTPCRMPandSTPsRiskManagedTechnicalSpeci"cations(RMTS).RMTSiscurrentlyuniqueto STP.Asapilotforarisk-informedapproachtoGSI-191debrisissues,STPdid notrelyonRMTSanddoesnotconsiderRMTSimplementationnecessaryfor adoptionoftherisk-informedmethodologyforrespondingtodebrisissuesas theymayTechnicalSpeci"cation(TS)requirements.STPassessesinoperableornonconformingconditionsinaccordancewithproceduresbasedontheguidanceofPart9900oftheNRCInspectionManual.

Thisincludesconditionsthatthesystemswithinthescopeofthislicensing applicationthataresupportedbythesumps;i.e.,ECCSandCSS.STPsex-pectationisthatapplyingRMTStocalculatearisk-informedcompletiontime (RICT)foranemergentdebrisrelatedconditionwillberare.Mostemergent debrisrelatedconditionsareresolvedwithintheoriginalfrontstopcompletion timebypromptremovalofthedebris.Ifadegradedornonconformingconditionrelatedtodebristhefunc-tionoftheemergencysumpsisdiscovered,itwillbeevaluatedinaccordancewith Part9900asnotedabove.TheShiftManageroftheunitwilllikelyre-questapromptoperabilityevaluationbyEngineering.Engineeringwouldmake adeterminationofwhetherthedebriscouldsigni"cantlytheevaluations describedinthisapplicationbyconsiderationofthenature,quantityandloca-tionofthedebris.IfEngineeringdeterminesthedebrisisadequatelyrepresented bytheexistinganalysis,theywillrecommendthatthesumpsareoperable,no TSactionwouldapplyandtheconditionwouldberesolvedinaccordancewith thestationscorrectiveactionprogram.IfEngineeringrecommendsthatthe sump(s)shouldbeconsideredinoperable,andtheconditioncanbequanti"edin theCRMP,thenaRICTmaybecalculated.Therequirementsforapplication ofRMTSareincorporatedintotheindividualTechnicalSpeci"cations(TS)and inanAdministrativeControlProgramTS6.8.3.k,whichinvokesNEI06-09,all ofwhichareimplementedbystationprocedures.Typically,quanti"cationoftheriskwiththedegradedornonconformingcon-ditionwillbeperformedinaccordancewithstationproceduresbyconservatively failingorotherwiseadjustingfunctionsinRICTCal,whichisadatabase ofthousandsofpre-quanti"edPRAplantcon"gurations.Thequanti"cationwill representtheactualplantcon"gurationwiththeinoperablecomponents,includ-inganyotherPRAmodeledcomponentsorfunctionsthatareunavailableatthat time.Thus,fortheexampleofECCS"ow,thequanti"cationwillincludetheTuesday1 stMarch,2016:19:32,Page177of393 DRAFTPART2.RAIRESPONSES(ROUND1)functionsbydebrisplustheunavailabilityofanyothertrainofECCSthatisunavailableatthetime.IfthePRAfunctionalallowanceis applied,thequanti"cationcanforcesomecomponentstobeunavailableforspe-ci"cinitiatingevents,suchaslargebreakLOCAs,whileretainingavailability forotherPRAinitiators.WithregardtochangestoPRAapplications,theSTPRICTCaldatabasewouldbeupdatedtotakeintoaccounttheimpactofthedebrisrelated totheconcernsraisedGSI-191applicabletoequipmentfunctionsinamanner consistentwiththecurrentpracticesde"nedintheSTPCRMPandprogram-maticupdateoftheSTPPRA.Nochangeswouldbenecessaryfortheprocess forprovidingtheassociatedRICTtotheplant2.1.5.2STSB:Question2STPResponse:(Item2,Page81)TheSTPTSBasesdescribetherequirementsgoverningPRAfunctionalityandareexcerptedbelow.Thelastbulletoftheexamplelistisrelevanttodebris relatedconditions.TheresponsetoRAI1,above,alsoaddressestheapplication ofPRAfunctional.TheSTPTSBasesguidanceisconsistentwithSection 2.3ofNEI06-09,Revision0.Thekeyfactorsare:1.TheCRMPallowsapplicationofRMTSforemergentsituationswherealltrainsofafunctionareinoperable,providedthereisPRAfunctionality, butdoesnotallowapplicationofRMTSforacompletelossoffunction.If functioniscompletelylost,thenon-RMTSallowedoutagetimemustbeapplied.

2.ForconditionswherePRAfunctionalitymaybeapplied,theriskfromthe con"gurationmustbequanti"ableusingthePRA.Forsuchcases,PRAinputs wouldbemodi"edtoobtainnewcon"gurationriskvaluesconsistentwithSTP existingproceduresandprocesses.STPTSBasesExcerpt:ApplicationoftheCRMPwillprovideactionforconditionswheremorethanonetrainorchannelofafunctionisinoperable.Inaccor-dancewithNEI06-09,aRICT(Risk-informedCompletionTime) maynotbeappliedforcon"gurationswherethereisacompleteloss offunctionorforpre-plannedactivitieswhenalltrainsofequipment requiredbytheTSLCOwouldbeinoperable.Itispermissibleto applyaRICTforemergentconditionswherealltrainsofequipment requiredbytheLCOareinoperableprovidedoneormoreofthe trainsarefunctionalasdescribedintheguidance.Ifacomponentisdeterminedtobeinoperable,itmaystillbecon-sideredtohavePRAFunctionalityforcalculationofaRICTifthere isreasonableassurancethatitcanperformitsrequiredfunctionsfor eventsnotbythedegradedornon-conformingconditionand iftheconditioncanbequanti"edinthePRA.Iftheseconditionsare notmet,thecomponentwillbeassumedtobenon-functionalfor calculatingtheRICT;i.e.,itwillhavenoPRAFunctionality.ExamplesofwhereacomponenthasPRAFunctionalitysuchthattheconditioncouldbequanti"edinthedeterminationofanallowed outagetimearelistedbelow:Tuesday1 stMarch,2016:19:32,Page178of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• SSCs(Systems,Structures,Components)thatdontmeetseis-micrequirementsbutareotherwisecapableofperformingtheir designfunction.

• SSCsthatareinoperablebutsecuredintheirsafeposition(e.g.,aclosedcontainmentisolationvalve).

• SSCspoweredfromasourceotherthantheirnormalpowersource,providedthealternatepowersourceismodeledinthe

PRA.*AnSSCwithaninoperableautomaticfunctionifthemanualactuationoftheSSCismodeledinthePRA(e.g.,adieselgen-eratorwithaninoperablesequencer).Actuationchannelsare associatedwiththeiractuatedcomponentsortrains.Lossof actuationchannelsisnotconsideredaLossofFunctionunless notrainoftheactuatedSSCfunctionhasPRAFunctionality.

• AnSSCthatisfunctionalformitigationofasetofevents(e.g.steamgeneratortuberupture,smallbreakLOCA)butisnot functionalforothereventsforwhichitiscredited(e.g.large breakLOCAorsteamlinebreak),providingthePRAmodel canquantifytheriskforthecalculationofaRICT.Anexam-pleofthistypeofconditionisdegradationofenvironmental

quali"cation.2.1.5.3STSB:Question3STPResponse:(Item3,Page82)Insulationreplacementinsidecontainmentiseitheralike-for-likereplacementasamaintenanceactivity(rework)orisamodi"cationwithadesignchange thathasbeenapprovedbySTPNOCEngineering.TheSTPNOCdesignchangeprocessproceduresensurethatnewinsulationmaterialthatfromtheinitialdesignisevaluated.TheSTPNOCdesign changeprocessalsocallsforevaluationsofaddedmetalssuchasaluminumthat couldcontributetopost-LOCAchemicalinthesumpwater.Theprocess looksatcoatingsthataretobeusedinsidecontainment.Impactstopost-LOCA recirculation"owpathsandrecirculationsumpdebrisimpactoninternalsof "uidcontainingcomponentsarepartofthedesignchangeevaluationprocess describedintheprocedure.Examplesofwherereevaluationoftheimpactzonewouldbewarrantedin-clude:*Introductionofanewtypeofmaterial

• Increaseofexisting"brousmaterial

• IncreaseofexistingaluminummaterialProceduresandActivitiesintheLicensingBasisinPartIofEnclosure4-1andSection3.3.4ofEnclosure3toReference1ofthecoverletterprovide additionalinformation.Tuesday1 stMarch,2016:19:32,Page179of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2ML14178A481,Secondsetofresponses2.2.1APLABResponses2.2.1.1APLAB,CASAGrande-LOCAFrequencies:Question2 STPResponse(Item2,Page37)TheimplementedcontinuumbreakmodelforSTPNOCyieldsaconditionallikelihoodofadouble-endedguillotinebreak(DEGB)of0.165.Twoalternative modelsareexploredtodeterminetheimpactofthecontinuummodel.The"rst alternativemodelassumesthatallbreaksareDEGBbreaks.Ifthefrequencies fromNUREG-1829arepreserved,this"rstalternativemodelresultsinalower frequencyofbreaksforlargerpipes.Asecondalternativemodelwasexplored inwhichthebottom-upweightingfactorswerenotused.Inotherwords,for thissecondalternativemodel,allpipeswithinasizecategoryhadthesame breakfrequency.Inthissecondalternativemodel,theconditionallikelihoodof aDEGBis0.0746,indicatingthebottom-upportionofthebasemodelused resultsinanincreaseinthefrequencyofaDEGBbyapproximatelyafactorof

2.DetailsaredocumentedinEnclosure1,STP-RIGSI191-RAI-APLA-III-2,Rev.1,RAIAPLA-III-2:ModelingLOCAFrequencyandBreakSizeunder DEGBonlyBreaks,UniversityofTexas2.2.1.2APLAB,STPPRAModel-General:Question2 STPResponse(Item2,Page40)TherisksassociatedwithGSI-191phenomenaareonlyconsideredtobepotentiallysigni"cantforinternalevents.Therefore,whiletheSTPProbabilistic RiskAssessment(PRA)hasnotbeendemonstratedtobefullycompliantwith RG1.200,Revision2,thedbetweenRevision1andRevision2are concernedwithexternalevents.Sinceexternaleventsarenotrequiredinput fortheassessmentofGSI-191phenomena,thisimpliesthattheSTPPRAis tforaddressingtherisksassociatedwithGSI-191phenomena.DeterminationofAdequacyofPlant-Speci"cPRAtoSupportRisk-InformedResolutionofGSI-191,Rev.1includedasEnclosure2supportsthisposition.2.2.1.3APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5STPResponse:(Item5,Page44)TheoperatoractionsonPage37ofVolume3arelistedas:1.SecuringoneContainmentSpraySystem(CSS)pumpifallthreeCSSpumpsaresuccessfullyinitiated2.SecuringallCSSpumpslaterintheevent 3.SwitchovertoEmergencyCoreCoolingSystem(ECCS)sumprecirculationaftertheRefuelingWaterStorageTank(RWST)hasbeendrained4.SwitchovertohotleginjectionTuesday1 stMarch,2016:19:32,Page180of393 DRAFTPART2.RAIRESPONSES(ROUND1)The"rsttwoactionsareincludedintheSTPProbabilisticRiskAssessment(PRA)logicmodelasswitchesbuttheirsuccessorfailurestatusdoesnot thesequenceofeventsmodeled.Theyareincludedinthemodelincaselaterit isdesiredtoperformsensitivitystudies.Theirstatusdoesnottheproba-bilityofsuccessorfailureofactions3and4.Action1isdirectedbyprocedure ReactorTriporSafetyInjection,0POP05-EO-EO00,ConditionalInformation Page.Action2isdirectedbyprocedureLossofReactororSecondaryCoolant, 0POP05-EO-E010,step16C,thisalsorequirescontainmentpressuretobeless than6.5psigandprovidedtheTechnicalSupportCenter(TSC)concurs.Action3,switchovertosumprecirculation,isassumedtoresultincoredam-ageiffailed.Thisisconsistentwiththebasemodelandhasnotbeenchanged inthemodelupdatedtoconsiderGSI-191phenomena.Shortoftdebris tocauselossofsumprecirculation,thepresenceofpartialdebrisinthesump isnotanticipatedtoimpacttheoperatorsperformanceofthisaction.Please alsoseetheresponsetoRAIAPLAB,STPPRAModel-HumanReliability Analysis:RAI6inSTPlettertoNRCdatedMay22,2014,NOC-AE-14003103, (ML14149A434).Action4,switchovertohotleginjection,followsaction3inthesequence,toalignforECCSsumprecirculationtothecoldlegs.Precedingaction3is alwayssuccessfulwhenaction4isqueriedsinceaction4isonlyofinterestif coredamagehasnotalreadyoccurred.Therefore,nodependenceisassumed betweenactions3and4.Thestatusofaction3isalwaysassumedsuccessfulinCASAGrande,beforeconsideringtheGSI-191phenomenasinceitsfailurealreadyguaranteescore damageformediumandlargeLossofCoolantAccidents(LOCAs).Sinceac-tions1and2donotimpacttheSTPPRAlogicmodel,thereisnoneedto interfacetheexacttimingoftheactionsinCASAGrandewiththeresponsein theSTPPRA.Action4,switchovertohotleginjection,occursafterthetimes ofgreatestinterestinCASAGrande,inparticularthoseinvolvingfailuresof sumprecirculation.Fuel"owblockagefailureisboundedbythefailurecriteria forboronprecipitation.BoronprecipitationrelatedtoGSI-191phenomenaends atthetimeofswitchovertohotleginjection.Oncehotleginjectionissuccessful thiseliminatesthepotentialforexcessiveboronprecipitationafterthattime.If switchovertohotleginjectionfails,thestatusofboronprecipitationafterthat timeisnotofinterestbecauseboronprecipitationisassumedforthefraction ofbreaksinthecoldleg.Consequently,informationaboutswitchovertohotleg injectionassumedinCASAGrandealsoneednotbetransferredtotheSTP PRAlogicmodelforevaluation.

Reference:

1.Letter,G.T.Powell,STPNOC,toNRCDocumentControlDesk,FirstSetofResponsestoApril,2014,RequestsforAdditionalInformationRegarding STPRisk-InformedGSI-191LicensingApplicationRevised,May22,2014, NOC-AE-14003103(ML14149A434)2.2.2ESGBResponses 2.2.2.1ESGB,ChemicalQuestion3 STPResponse:(Item3,Page54)Tuesday1 stMarch,2016:19:32,Page181of393 DRAFTPART2.RAIRESPONSES(ROUND1)TheexponentialProbabilityDensityFunction(PDF)isashifted,truncated,andsingle-parameterfunctionthatrequiresonlythemeanvaluetospecify theentirecontinuousdistributionforallx>1,wherexisthechemicalhead-lossfactor.Themaximumchemicalfactorsforsmall,mediumandlarge breaks-15.3forsmallbreakLOCA(SBLOCA),18.2formediumbreakLOCA (MBLOCA),and24forlargebreakLOCA(LBLOCA)werecalculatedasper-centilesoftheirrespectivedistributionsthatpreserveatailprobabilityof1E-05.

Thismeansthatonly1in100,000randomsamplesfromthedistributionwould begreaterthanthereportedmaximum.Themaximawereincludedinevery Latinhypercubesample(LHS)replicate,andtheywereassignedaweightof 1E-05torepresentallchemicalfactorsthatmightbehigher.Assignmentofamaximumchemicalfactorat1E-05isonlyarbitraryinthesensethatthischoicecontrolstheprobabilityweightcarriedbyanyfailures inducedbychemicalfactorssampledfromthehigherrangeofthedistribution.

Theweightof1E-05waschosentocorrespondtopercentilesthatensureaquan-ti"ablenumberofchemicallyinducedEmergencyCoreCoolingSystem(ECCS) failures.Ifnoinducedfailureswereobserved,thenthemaximawouldindeed besuspect,andthetailprobabilitywouldneedfurtherreduction.Withcon-ventionaldebrisheadlossintherangeofafewfeetandastructurallimitof only9.35ft.,chemicalfactorsexceeding10leadtofailure.Therefore,these-lectedmaximawouldbeconsideredconservativefortheLossofCoolantAcci-dent(LOCA)spectra.Beyondthestatedmaxima,probabilityweightsbecome vanishinglysmall,andsamplingbeyondthestatedmaximawouldnotinduce anyadditionalfailures.2.2.2.2ESGB,ChemicalQuestion7 STPResponse:(Item7,Page55)ChemicalHeadLossExperiment(CHLE)TankTests1and2(theMBLOCAandLBLOCAtests)didnotresultintheformationofchemicalprecipitates.

Basedonthealuminumconcentrationsmeasuredinsolution,thoseresultswere consistentwiththeexistingequilibrium-basedmodelforthepredictionofthe thresholdconcentrationsofspeciesthatcouldresultinprecipitation.Experi-mentsconductedbyArgonneNationalLaboratory(ANL)wereidenti"edthat supporttheequilibrium-basedmodel.Figure1isareprintfromAluminum SolubilityinBoronContainingSolutionsasaFunctionofpHandTemperature (ADAMSAccession#ML091610696)(1).This"gureshowstheresultsofalarge numberofbench-topandverticalloopexperimentsandotherliteraturedataat variouspHandtemperaturevalues,withseparationofthedataintoaregion whereprecipitationoccurredandaregionwhereprecipitationdidnotoccur.The authorspresentedequationsforempiricallinesseparatingthetworegionswith theexceptionofafewoutliers,andasecondsetofequationsforlines(shifted upward)thatencompassallinstancesofprecipitation.TheauthorsofRef.1subsequentlypublishedthedatainNuclearEngineeringandDesign(2).Thesecondpublicationincludedanadditionallineonthegraph showingthepredictionofthesolubilityofamorphousaluminumhydroxidebased onanequilibrium-basedmodel(VisualMINTEQ).Figure2isareprintofthe "gureanddemonstratesexcellentagreementbetweenANLsempiricalboundary linesandthepredictionsofVisualMINTEQ.UsingthesameapproachastheTuesday1 stMarch,2016:19:32,Page182of393 DRAFTPART2.RAIRESPONSES(ROUND1)original"gure,anupwardshiftoftheVisualMINTEQlinewouldencompassallinstancesofprecipitation.TheupwardshiftoftheVisualMINTEQlineneces-sarytoencompasstheprecipitationdataisa0.45-unitincreaseinpH+p[AI]

T;inaddition,thisupwardshiftencompassesallprecipitationdatathroughoutthe entiretemperaturerangewithasingleequation,whereastheempiricalbound-ariesinRef.1includedaseparateequationforthedataabove72C(175F).Figure1:(ReprintedfromRef.1):AlstabilitymapinthepH+p[AI]

Tvs.temperaturedomainforsolutionscontainingboron.Filledandopensymbolsmeantheoccurrenceof Alhydroxideprecipitationandnoprecipitation,respectively.pH+p[AI]

TmeansthesolutionpHattemperatureandthenegativelogtothebase10ofthetotalaluminum contentasdissolvedorprecipitateinunitsofmol/kg.CHLETankTests3and4weredeveloped(asareplacementforthetestsde-scribedintheoriginaltestplan)tocon"rmthevalidityoftheliteraturedataand theexistingVisualMINTEQmodelforamorphousaluminumhydroxidesolubil-itywiththeplant-speci"cchemistryatSTP.Figure3presentstheresultsofall 5CHLEtanktestsinthesameformatastheANLdata.Thedatademonstrate thatCHLETankTests1,2,and5occurredinthenon-precipitationregion,and thattheprecipitationthatresultedfromexcessivequantitiesofaluminumin CHLETankTests3and4wereconsistentwiththeexistingdataandmodel.An upwardshiftof0.45unitsofpH+p[AI]

TencompassestheprecipitationdataofTests3and4;thisupwardshiftissimilartothatnecessarytoencompassthe precipitationregionintheANLdata.SinceCHLETankTests3and4adequatelycon"rmedthethresholdconcen-trationsatwhichprecipitationwouldoccurbasedonexistingmodelsanddata, noadditionaltestsareplanned.TheconsistencybetweentheresultsofCHLETuesday1 stMarch,2016:19:32,Page183of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:(ReprintedfromRef.2):AlhydroxideprecipitationmapinthepH+p[AI]

Tvs.temperaturedomainbasedonANLsbenchtopandlooptestdataandliterature data.TankTestsandexistingdataandmodelprovidesjusti"cationfortheengineer-ingjudgmentapproachusedforaluminumsolubilityinthelicensesubmittal.

However,theengineeringjudgmentwasbasedonadirectapplicationoftheVi-sualMINTEQamorphousaluminumhydroxidesolubilitypredictionwithoutthe shiftof0.45units,sincethelicensesubmittaloccurredbeforeCHLETankTests 3and4hadbeenconducted.Theshiftof0.45unitsresultsinasmallreduction oftheconcentrationatwhichaluminumprecipitatesintherangeofpH7.0to 7.3at60C(140F).

References:

1.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,andNatesan,K.AluminumSolubilityinBoronContainingSolutionsandaFunctionofpHandTemperature.ADAMS AccessionNo.ML091610696,ArgonneNationalLaboratory,September,2008.2.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,Natesan,K,andKlein,P.Eval-uationofprecipitatesusedinstrainerheadlosstesting:PartIll.Long-term aluminumhydroxideprecipitationtestsinboratedwater.NuclearEngineering andDesign,vol.241,no.5,pp.1914-1925,2011.Tuesday1 stMarch,2016:19:32,Page184of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure3:AlhydroxideprecipitationmapoftheCHLETankTestsinthepH+p[AI]

Tvs.temperaturedomain.Opensymbols(gray)indicateresultswhereprecipitationwas notobservedandclosedsymbols(black)indicatewhereprecipitationwasobserved.Eachtestisrepresentedbyanapproximatelyhorizontalseriesofdatapoints(near-constantvaluesofpH+p[AI]

Tasthetemperaturedeclinedoverthedurationofthetest).Tuesday1 stMarch,2016:19:32,Page185of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.2.3ESGB,ChemicalQuestion11aSTPResponse:(Item11a,Page56)Itispossibleforfallingwaterfromapipebreakorotherlocationstoimpingeonthegratingsorothergalvanizedsurfaceswithinthecontainmentbuilding.

Directjetimpingementfromabreakcouldcausedamagetogalvanizedsurfaces butwouldbeforarelativelyshortdurationandoveralimitedarea.Continued impingementfromtheContainmentSpraySystem(CSS)couldoccurforseveral additionalhoursuntilthesystemissecured.Ifgalvanizedsurfacesarelocated belowthebreak,fallingwatercouldimpingeonthesurfacesevenafterthesystem issecured,althoughthesurfaceareaimpingedinthismannerwouldbelimited inextent.ChemicalHeadLossExperiment(CHLE)tankteststhatcontainedgalva-nizedsteelorzincsurfacesexperiencedaninitialpeakinturbidityandzinc concentrations,asdescribedintheCHLE-020document(1).Testingconducted foranotherlicenseeaftertheSTPlicensesubmittaldemonstratedthatthezinc releasewasassociatedwiththeinitialperiodoflowpHwhenTri-sodiumPhos-phate(TSP)wasnotpresent(2)WhenTSPwaspresentandthepH wascircumneutral,theinitialreleaseofzincdidnotoccur.Thus,itisexpected basedonthecurrentdatathattheperiodoftimethatzincwouldbereleased fromgalvanizedsurfaceswouldbelimitedtotheinitialportionoftheaccident sequencebeforetheTSPhasfullydissolvedintothecontainmentsolution.

References1.UNM,CHLE-020:TestResultsfora10-daychemicaltestsimulating LBLOCAconditions(T5),Rev.3.UniversityofNewMexico,Albuquerque,NM.

Feb.22,2014,ML14072A079.2.UNM,CHLE-SNC-006:BenchTestResultsforSeries2000TestsforVogtleElectricGeneratingPlant,Rev.1.UniversityofNewMexico,Albuquerque,NM.

Nov.292013.2.2.2.4ESGB,ChemicalQuestion11b STPResponse:(Item11b,Page56)Zincfromgalvanizedsurfacesmightbeconsideredtocontributetoheadlossintwoways.First,zincproductsdislodgedfromgalvanizedsurfacesduringtheinitialphasesoftheLossofCoolantAccident(LOCA)(beforetheTSPdis-solves),asobservedinsomeoftheChemicalHeadLossExperiment(CHLE) tanktests,maycontributeanadditionalparticulatesourceduringtheinitial developmentofthedebrisbed.Thiscontributionwasconsideredtobesmall (lessthan10percent,basedonconcentrationsmeasuredinsolution)compared toothersourcesoflatentdebrisinthecontainmentbuildingandwasnotex-plicitlyconsideredasaseparatesourceofparticulate.Thesecondsourceofzinc fromgalvanizedsurfacesistheslowformationofzincphosphateonthegalva-nizedsurfaceduetoreactionsbetweenthezincinthegalvanizedcoatingand thephosphateinthesolution.VisualobservationsofthecouponsintheCHLE tanktestsindicatedthatthisproductformedslowlyoveraperiodofmanydays andremainedlargelyadheredtothecoupons.Whilequantitativeratesofzinc phosphateformationwerenotobtainedfromtheCHLEtanktests,qualitative observationsindicatedthattheproductwouldnotbepresentuntillaterintheTuesday1 stMarch,2016:19:32,Page186of393 DRAFTPART2.RAIRESPONSES(ROUND1)accidentsequencewhentemperatureswerelowerandstrainer"owrateswerelower,allowingadditionalmarginforheadlossthroughthestrainer.Analysis indicatedthattheproductwascrystalline,whichwouldbeexpectedtocon-tributetolessheadlossthanamorphouscorrosionproducts.Basedonthelate formationofthismaterial,itsadherencetosurfaces,andcrystallinenature,this materialwasconsideredlesssigni"cantintheSTPchemicalanalysisand itsformationwasnotexplicitlyconsideredintheanalysisdescribedinVolume 6.2.Thebump-upfactorusedtoapplychemicalheadlosswasnotcal-culatedonthebasisofindividualchemicalproducts,andthepotentialforzinc phosphatetobeacontributortochemicalheadlosswasimplicitlyconsidered duringthedevelopmentofthebump-upfactors.2.2.2.5ESGB,ChemicalQuestion17 STPResponse:(Item17,Page57)Everysimulatedbreakhasitsowntime-dependentconventionalheadlossthatiscalculatedbasedondebrisaccumulationand"owrate,andaddedto abaselineclean-strainerheadlossof0.22feetofwater.Chemicalfactorsare appliedtotheconventionalheadlosswhenthetemperatureislessthan140

+/-5Fandthe"berloadexceeds1/16in.equivalentthickness.Totalheadlossiscomparedateverytimesteptotheperformancemetricsof(1)NPSHavail,(2)voidfraction,and(3)mechanicalbuckling.Foreverybreakwithaconventionalheadlossintherangeof1ft.ofwaterandamechanicalloadinglimitofonly9.35ft.,achemicalhead-lossfactorexceeding 10willinducefailures.Achemicalhead-lossfactorof43wouldleadtobuckling failureofthestrainerforallsimulatedbreaksinCase01,fulltrainoperation.A chemicalhead-lossfactorof209wouldleadtotheviolationoftheNPSHmargin criterionandfailureforallsimulatedbreaksinCase01,fulltrainoperation.ThesesolutionswereobtainedbyextractingthenecessarydatafromtheCASAGrandeCase01simulation.Anexampleforthelarge-breakpopulation ofchemicalfactorsneededtoinducemechanicalbucklingfailureisshownin FigureA.Thecumulativedistributionfunction(CDF)illustratesthepercentage ofLBLOCAcasesthatwouldfailforchemicalfactorsx.FigureA:CDFforminimumchemicalfactorrequiredtoexceedstrainerbucklinglimitforlargebreaks.Tuesday1 stMarch,2016:19:32,Page187of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.2.6ESGB,ChemicalQuestion20STPResponse:(Item20,Page59)PrototypicalSTP-speci"cstrainerheadlosstestswereconductedatAldenResearchLaboratory(ARL)inFebruary (1,2)andJuly,2008 (3,4).TheFebruaryheadlosstestsweresupersededbytheJulyheadlosstests,becausetheFebruary testsusedwalnut"ourasaparticulatesurrogate.Thereducedamountre"ects mostcloselytheamountofdebrisfromthemajorityofthelargebreaks.The CASAGrandeheadlosspopulationforCase01(allequipmentstartsandruns) wascomparedtoalloftheprototypicalstrainerheadlosstestsconductedat ARL.ThemaximumconventionalCASAGrandeheadlosswas8.2ft,which boundsthemaximumtestedheadlossesforalloftheARLtests,exceptTest3 inFebruary.Test3wasterminatedafterlargeheadlosses,greaterthan15ft, wereobservedfollowingtheadditionof"ne"brousdebris (2);asstatedabove,thistestusedwalnut"ourasaparticulatesurrogateandwassuperseded.The maximumpredictedchemicalCASAGrandeheadlosswas154.9ft,which boundsalltheARLtests.ThemaximumpredictedtotalCASAGrandehead losswas161.9ft,whichboundsalltheARLtests.Also,expectedvaluesofexponentialdistributionsappliedforchemicalhead-lossfactorswerechosentobeconsistentwithstrainertestdatashowingchemical inducedhead-lossincreasesofapproximatelyafactorof2.VogtleElectricGeneratingPlant(Vogtle)conductedprototypicalstrainerheadlosstestsattheAlionhydraulicslaboratory (5).Figure1displaysthepro-totypicalVogtleandSTPstrainermodules.BothmodulesarePCISure-Flow Rdesigns.AlltheSTPstrainertestswereconductedatanapproachvelocityof0.0086 ft/s (2,4);theVogtlestrainertestswereconductedatanapproachvelocityof0.0150ft/s (5).DebrisweightsperprototypicalstrainerareaforgeneraldebristypesaredisplayedinTable1.However,thespeci"cinsulationproductstested undereachdebris-typecategorybetweenthetwoplants.Forexample,STP testedNUKON RandThermalWrapunderthelow-density"berglass(LDFG)category,whereasVogtleonlytestedNUKON RundertheLDFGcategory.Figure1:Vogtle(left)andSTP(right)PrototypicalStrainersUtilizedforTesting.Themaximumconventional,chemicalandtotalheadlossespredictedbyCASAGrandeforCase01alsoboundVogtlesprototypicalstrainerheadloss testing,whichmeasured5.5ft,6.3ft,and11.8ft,respectively (5).Tuesday1 stMarch,2016:19:32,Page188of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table1:DebrisComparisonbetweenSTPandVogtle (2,4,5)UtilityTestLDFGFinesper Strainer Area, lbm/ft2LDFGSmallsper Strainer Area, lbm/ft 2Particulateper Strainer Area, lbm/ft 2CalciumPhos-phate,lbm/ft 2Aluminum Oxyhydroxide, lbm/ft 2SodiumAluminum Silicate, lbm/ft 2STPFeb.Test40.220.31.160.10.430 STPFeb.Test50.140.191.160.10.430STPJulyTest20.060.110.640.10.450VogtleAllTests0.310.146.60.0900.14Fortheheadlosscomparisonscitedabove,theSTPtestsatARLandVogtletestsatAlionwerenotcorrectedtoacommon"owrateandtemperature,which isconservative.Thetemperaturerangeforthesetestswas51Fto117F (1-5)andthetemperaturerangeforCASAGrandeis117Fto255F(LAREnclosure4-3,Table2.2.13)correctingtheteststoahighertemperaturewouldreducethe headloss.TheARLtestsmodeledthemaximumSTP"owcondition.Case 01ofCASAGrandewassimulatedatthemaximumSTP"owcondition,but containmentspraypumpsweresecuredduringtheLOCA.Therefore,theCASA Grandeheadlosspopulationmayinherentlyincludeheadlossesat"owrates lowerthantheARLtestcondition.TheVogtletestswereconductedatahigher "owratethantheSTPtests.Therefore,correctingtheVogtleteststoalower "owratewouldreducetheheadloss.Allfactorsconsidered,thebenchmark comparisonsofmaximalcomputedheadlossmeetorexceedallapplicabletest dataforSTPandVogtle.

References

1.0415-0100067WN/0415-0200067WN.SouthTexasProjectTestPlanFeb 2008.RevisionA.11/24/2008.

2.0415-0100069WN/0415-0200069WN.SouthTexasProjectTestReportfor ECCSStrainerPerformanceTestingFeb2008.RevisionA.11/24/2008.

3.0415-0100070WN/0415-0200070WN.SouthTexasProjectTestPlan.Re-visionA.8/14/2008.

4.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportfor ECCSStrainerTestingJuly2008.RevisionA.11/24/2008.

5.ALION-CAL-SNC-7410-005.HeadLossTestingofaPrototypicalVogtle1 and2StrainerAssembly.Revision0.12/31/2009.2.2.2.7ESGB,ChemicalQuestion22a STPResponse:(Item22a,Page59)ThetestsdescribedinCHLE-010,CHLETankTestResultsforBlendedandNEIFiberBedswithAluminumAddition 1didnotcontainaluminumoxy-hydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.

IntheCHLE-010testseries,aluminumoxyhydroxideprecipitatewasgenerated byinjectinganaluminumnitratesolutiondirectlyintothetankrecirculation line.Thealuminumnitratesolutionwasinjectedinperiodicbatchesataslow ratecorrespondingtoanincreaseinaluminumconcentrationinthetankof0.02 mg/Lperminute.Precipitationoccurredwhenthealuminumnitratecamein contactwiththesolutioninthetank,whichcontainedplant-speci"cconcen-trationsofboricacid,lithiumhydroxide,andtri-sodiumphosphate(TSP)andTuesday1 stMarch,2016:19:32,Page189of393 DRAFTPART2.RAIRESPONSES(ROUND1)washeatedtoabout45degreesFatthetimeofaluminumnitrateinjection.Incontrast,theWCAP-16530-NP-Aprotocolinvolvesamorerapidadditionof solidaluminumnitrateandsodiumhydroxideintonormalpotablewaterina mixingtankatambienttemperaturewithatargetaluminumoxyhydroxidecon-centrationbetween2,100and11,000mg/L.TheCHLE-010testsweredesigned tosimulatetheslowreleaseofaluminumduringcorrosionandtheconditionsfor precipitateformationweresubstantiallydtfromtheWCAP-16530-NP-A protocol.Earliertests,describedinCHLE-008,DebrisBedPreparationandForma-tionTestResults 2andprovidedtotheNRCSinSTPLetterNOC-AE-14003075,datedFebruary27,2014(ML14072A076),didincludealuminumoxy-hydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.

Inthosetests,additionoftheWCAPprecipitatestocolumnswiththesame typeofdebrisbedastheMBLOCAandLBLOCAtests(theNEI-prepared debrisbed)didresultinsubstantialheadloss.InCHLE-008Test5,thead-ditionofWCAPprecipitatestoanNEI-prepareddebrisbedatanapproach velocityof0.093ft/scausedsucharapidincreaseofheadlossthatthestain-lesssteelsupportscreencollapsedbeforetheentirebatchofprecipitateswas added.InCHLE-008Tests6and8,additionofWCAPprecipitatetothecol-umnresultedinsubstantialheadlossthroughtheNEI-prepareddebrisbedat anapproachvelocityof0.01ft/s,whichiscomparabletothatoftheSTPstrain-ers.Thequantityofaluminumoxyhydroxideprecipitatethatcausedsigni"cant headlosscorrespondedtoascreenloadingof246g/m2.Forcomparison,the strainertestingdoneforSTPatAldenResearchLaboratorybyAREVA 3 hada"nalaluminumoxyhyroxideprecipitatescreenloadingof2,200g/m2.Test13 inCHLE-008involvedtheadditionofWCAPprecipitatestotheCHLEtank andexcessiveheadlosswasdetectedinallthreecolumns.TheCHLE-008test resultsdemonstratethatthedebrisbedsusedintheMBLOCAandLBLOCA testswerecapableofdetectingaluminumoxyhydroxideprecipitatesgenerated accordingtotheWCAP-16530-NP-Aprotocolviaaheadlossmeasurement.ThediscussionbetweentheNRCandSTPduringtheSeptember2012phonecallfocusedontherelativedegreeofsensitivitybetweentheNEI-prepareddebris bedsandtheblender-prepareddebrisbeds.TheCHLE-008andCHLE-010test resultsdemonstratedthatthethresholdloadingrateforthedetectionofhead lossinblender-prepareddebrisbedswaslowerthanintheNEI-prepareddebris beds.Unfortunately,theblender-prepareddebrisbedsexperiencedsigni"cant headlosswhenchemicalprecipitateswerenotpresentandexhibitedotherforms ofinstabilitysuchasanon-linearresponseto"uidvelocityorquantityof"ber, makingthemunsuitablefordetectionofchemicalprecipitatesintheCHLEtests.

Inaddition,acomparisonoftheloadingratesatwhichheadloss"rstoccurred intheNEI-prepareddebrisbedsintheverticalcolumnandthemixed-debrisbed intheAREVAstrainertestingindicatesthatthethresholdfordetectinghead lossisnotaslowintheNEI-prepareddebrisbedasitisinthemixed-debrisbed.

Thus,neithertheNEI-preparednortheblender-prepareddebrisbedsprovideda tmethodofdetectingchemicalprecipitatesviaaheadlossmeasurement.ItisalsoimportanttonotethattheMBLOCAandLBLOCAtestsemployedmultipleparameterstodetectthepresenceofprecipitatesinadditiontohead lossthroughthedebrisbeds.SampleswereperiodicallyanalyzedfortotalandTuesday1 stMarch,2016:19:32,Page190of393 DRAFTPART2.RAIRESPONSES(ROUND1)dissolvedaluminumperiodicallyduringbothtests.Nosigni"cantbe-tweentotalanddissolvedaluminumwasdetected,indicatingthatallaluminum wasinadissolvedform.Themeasuredtotalconcentrationswerebelowthesat-urationconcentrationpredictedforamorphousaluminumhydroxidebyVisual MINTEQ,corroboratingtheevidencefromthetotalanddissolvedmeasure-ments.TurbidityremainedlowthroughouttheMBLOCAandLBLOCAtests.

ResultsreportedinCHLE-010demonstratedalinearresponsebetweenthead-ditionofaluminumandtheturbidityofthesolution,indicatingthatturbidity iscapableofdetectingprecipitatesthatforminthisexperimentalsystem.Thus, evenintheabsenceofthecolumnheadlossdata,theresultsfromtheMBLOCA andLBLOCAtestscanbeusedtodemonstratethataluminumchemicalpre-cipitatesdonotforminthesimulatedMBLOCAandLBLOCAenvironments.Toaccountfortheuncertaintyassociatedwiththeheadlosscharacteristicsofvariousdebrisbedsandthevariouswaysofgeneratingchemicalprecipitates, safetymarginwasaddedtothechemicalcontributiontoheadlossby applyingabump-upfactortothecalculatedvalueofconventionalheadlossas describedintheLAREnclosure4-1,page9andinmoredetailinLAREnclosure 4-3,Section5.6.3.Thechemicalheadlossbump-upfactordidnotdirectlyuse headlossdatafromtheCHLEtests.Asaresult,theabilityofthetestscreen debrisbedtodetectchemicalprecipitateshasshownnottoin"uencetheresults describedintheSTPlicensesubmittal.

References

1.UniversityofNewMexico,CHLE-010:CHLETankTestResultsforBlendedandNEIFiberBedsWithAluminumAddition,Rev.3.Feb.10,2014.(ML14072A083)2.UniversityofNewMexico,CHLE-008:DebrisBedPreparationandFor-mationTestResults,Rev.4.Feb.3,2014.(ML14072A082)3.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting,Doc.66-9088089-000.2.2.2.8ESGB,ChemicalQuestion22b STPResponse:(Item22b,Page59)TheobjectiveoftheCHLEtestingprogramwastogenerateexperimentaldatatosupportanoverallrisk-informedapproachtotheresolutionofGSI-191,whilealsoconductingamanageablenumberoftests.Eachtestwithinthe programhadmultipleobjectives,withtheintentthatthetestingprogramas awholeprovideddatatosupporttheresolution.Inclusionofallmaterialsin alltestswouldnotnecessarilyhaveprovidedthemostcomprehensivedata, sinceinsomecasesthepresenceofonematerialmightreducethecontribu-tionofchemicalfromanothermaterial.InthecaseoftheMBLOCA andLBLOCAtests,theinclusionofzincintheLBLOCAtestandnotinthe MBLOCAtest,coupledwithcomparisonsofpredictedreleaseratesfromthe WCAPequations,demonstratedthatthereleaseofaluminumwasgreaterwhen zincwasnotpresent.Thatimportantoutcomewouldnothavebeenrecognized ifzinchadbeenincludedinalltests.WhilethetestsincludeddtmaterialsandaspectsoftheLOCAtosat-isfydtobjectives,theconditionswithineachtestwererepresentativeofthe plant-speci"cenvironmentfortheincludedmaterials.Manyfactors,including thequantitiesofboricacid,tri-sodiumphosphate(TSP),andlithiumhydroxide;Tuesday1 stMarch,2016:19:32,Page191of393 DRAFTPART2.RAIRESPONSES(ROUND1)thetimingofTSPdissolution,acidgeneration,andsprayduration;thetemper-aturepro"le;andapproachvelocitythroughthescreenswereallrepresentative oftheplant-speci"cenvironment.FortheMBLOCAtest,thequantitiesofalu-minumand"berglasswerealsorepresentativeoftheplant-speci"cenvironment duringaMBLOCA.2.2.3SCVBResponses 2.2.3.1SCVB,Question:1a STPResponse:(Item1a,Page61)Section1ofEnclosure2-3ofthelicenseamendmentrequest(LAR)identi"estheContainmentSpraySystem(CSS)astheonlysystemforwhichtheproposed exemptiontoGDC-38wouldapply.TheCSSistheonlysystemcreditedfor meetingGDC-38thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftherisk-assessmentprovidedintheSTPlicensing

application.2.2.3.2SCVB,Question:1b STPResponse:(Item1b,Page61)ThesecondparagraphofGDC-38prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-38utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailure in10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethat couldresultinthefailureofmultiplecomponents.Therisk-informedassessment demonstratesthechangeincoredamageorlargeearlyreleasefrequencyfrom thedebrisisverylowinaccordancewiththeguidanceofRG1.1742.2.3.3SCVB,Question:2a STPResponse:(Item2a,Page61)Section1ofEnclosure2-4ofthelicenseamendmentrequest(LAR)identi"estheContainmentSpraySystem(CSS)astheonlysystemforwhichtheproposed exemptiontoGDC-41wouldapply.TheCSSistheonlysystemcreditedfor meetingGDC-41thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftherisk-assessmentprovidedintheSTPlicensing

application.2.2.3.4SCVB,Question:2b STPResponse:(Item2b,Page61)ThesecondparagraphofGDC-41prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-41utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailureTuesday1 stMarch,2016:19:32,Page192of393 DRAFTPART2.RAIRESPONSES(ROUND1)in10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethatcouldresultinthefailureofmultiplecomponents.Therisk-informedassessment demonstratesthechangeincoredamageorlargeearlyreleasefrequencyfrom thedebrisisverylowinaccordancewiththeguidanceofRG1.174.2.2.3.5SCVB,Question:3a STPResponse:(Item3a,Page62)ThelicensingbasisfortheassessmentoftheeofdebrisisbeingrevisedandthedescriptionoftheriskassessmentwillbedescribedintheSTPUFSAR asdiscussedinthelicenseamendmentrequest,Enclosure3,Attachment2.The resultsoftherisk-informedassessmentdemonstratethatthecontainmentsumps aretlyreliableinsupportoftheContainmentSpraySystem(CSS)such thatthefunctionoftheCSSwithrespecttocontainmentanalysisremainsas currentlydescribedintheUFSAR.2.2.3.6SCVB,Question:3b STPResponse:(Item3b,Page62)BackgroundandReferencetoSubmittalDocumentation Theproposedmethodologyisnotconservativewithrespecttoinputsandas-sumptions.Theproposedmethodologyisnotproposedtoreplacetheconservatively-basedmethodologydescribedintheUFSAR.Moredetailsareprovidedinthe followingparagraphsandtables.AsdescribedintheLAR,theproposedexemptionsfromGeneralDesignCri-teria(GDC)-35,theEmergencyCoreCooling,GDC-38,ContainmentHeat Removal,andGDC-41,ContainmentAtmosphereCleanupareforapproval ofarisk-informedapproachforaddressingGSI-191andrespondingtoGeneric Letter(GL)2004-02forSTPUnits1and2asthepilotplantsforotherlicensees pursuingasimilarapproach.Asfurtherdescribed,STPNOCseeksNRCapproval basedonadeterminationthattherisk-informedapproachandtheriskassoci-atedwiththepostulatedfailuremechanismsduetoGSI-191concernsmeetsthe guidance,keyprinciplesforrisk-informeddecision-making,andtheacceptance guidelinesinRG1.174.STPisnotproposingtoapplytherisk-informedapproachtorevisetheli-censingbasisforcontainmentdesigndescribedintheUFSAR.Theproposedrisk assessmentevaluatesaspectrumofLossofCoolantAccident(LOCA)scenarios toquantifytheamountofdebrisofvarioustypesthatmightbegeneratedand transportedtotheemergencysumps,andhowthatdebrismightavailable NPSHforEmergencyCoreCoolingSystem(ECCS)andContainmentSpray System(CSS)pumpstakingsuctionfromthesumpsintherecirculationmode.

Italsoevaluatespotentialtransportofdebristothereactorcore.Itcalculates failureprobabilitiesthatarefedtotheSTPPRA.BecausetheLARisbasedonarisk-informedanalysis,thenatureoftheen-gineeringsupportinseveralareasfordecision-makingisfundamentallyt fromthemethodsusedintheexistingdeterministically-basedLicensingBasis (LB)analyses.Thecontainmentanalysisisanexampleofsuchanareaofd ence.Therisk-informedapproachtoresolvingGSI-191appliestheProbabilistic RiskAssessment(PRA)modeltoquantifytheriskassociatedwithGSI-191 concernsbycalculatingtheinriskfortwocases:Tuesday1 stMarch,2016:19:32,Page193of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• Theactualplantcon"gurationforSTPUnits1and2,withfailuresduetoGSI-191concerns,and

• Thesameplantcon"gurationforSTPUnits1and2,exceptfortheas-sumptionthattherearenofailuresduetoGSI-191concerns.Enclosure1totheLARprovidesthegenericmethodologyfortheproposedrisk-informedapproachtoresolvingGSI-191,consistentwithRG1.174guid-ance.ThisenclosuredescribestherequiredinputstothePRAmodel,thebasic structureforappropriatelymodelingtheinputs,andperformancecriteriaused tocalculatetherisk.AsdescribedinEnclosure1,therisk-informedapproachto resolvingGSI-191usestheplant-speci"cPRAwithrealisticmodelingtoquan-tifytheresidualriskassociatedwithGSI-191andtoevaluateforacceptable sumpdesigninsupportofsuccessfulECCSandCSSoperationinrecirculation modefollowingpostulatedLOCAswiththedebrisdiscussedinGSI-191.TheCurrentLBModelingApproachThelicensingbasis(LB)containmentanalysisisbasedontheCONTEMPTcomputercodeandisdocumentedinSTPcalculationNC07032.TheCON-TEMPTcodeisdocumentedintwoseparatedocuments,NUREG/CR3716and NUREG/CR4001.ThecurrentLBcontainmentanalysisuses260degreesFforthesump"uidtemperatureanddoesnotcontemplatestrainerfailureduetotheconcernsraised inGSI-191.Theanalysisisdesignedtomaximizecontainmentpressure(andtem-perature),whichwouldactuallyimprovenetpositivesuctionheadavailable.The conditionassumedintheLBanalysisisveryunlikelytoberealizedinoperation.

BecausetheLBCONTEMPTmethodologyisnotintendedtore"ectrealistic containmentresponsebehavior,andisbasedonanextremelyunlikelyscenario, theLBmodelingapproachdfromtheapproachusedforcompliancewith RG1.174requirements.Inparticular,CONTEMPT4hasbeenveri"edtoperformtwomajoranalyses[4,PageLOCAU-11]:

• containmentpeakpressureandtemperatureanalysis,and

• containmentenvironmentalthermodynamicconditionsforequipmentqual-i"cationandisolatedpipepressurizationpurposes.TheRiskInformedModelingApproachThecontainmentanalysisisbasedontheSTPMELCORmodelthatrunssimultaneouslywiththeSTPRELAP5modeldesignedforuseintheSTPPRA fortheevaluationrequiredintherisk-informedapproachforaddressingtheGSI-191issue.AsdescribedinLAREnclosure5,Item5.a.13:In-VesselFiberLimits, severalparametersrelatedtogeometry,thermalhydraulics/heattransfer,and engineeredsafetyfeaturesusedintheMELCORinputweretakenfromaprevi-ouslycerti"edModularAccidentAnalysisProgram(MAAP)STPcontainment model.Hence,thecerti"cationdocumentfortheMAAPmodelisappropriately referencedthroughoutthetext.Thefollowingtableliststhemajorqualitativedbymodelingsub-jectareabetweentheriskassessmentandLBcontainmentmodels.Inthenext section,numericalvaluesarecompared.Tuesday1 stMarch,2016:19:32,Page194of393 DRAFTPART2.RAIRESPONSES(ROUND1)SubjectRELAP/MELCORCONTEMPTSubcompartment analysisYesNoCONTEMPThas1largevolume(1pool,1atmosphere)andisnotvalidatedforsubcompartmentanal-ysis.MELCORhasseveralsub-compartments.ModelinggoalsContainmentpressureresponseSumpPooltemperaturere-sponsePeakPressureanalysis(struc-turaldesigntesting,leakrate testing)andcontainmentther-modynamicconditionsFundamentallytmodelinggoalsdrovethemodelingdecisions foreachcodeandexplainsomeof theinassumptionsfor eachmodel.ModelvariationsSinglecontainmentmodelre-gardlessofprimarysidecharac-teristics,breaksize,orstageof thetransient(e.g.before/after sumprecirculation)2separatemodels:oneforeachtransientstage(injection,re-circulation).Also,tas-sumptionsfortsteam generatortypes,primaryside characteristics,modelinggoals, etc.ThesingleMELCORmodelworksinconcertwithRELAP5-3Dforalltransientstages.Primarysidechar-acteristicsaretheexclusivedomain ofRELAP5-3Dduringacoupled run.TheCONTEMPTmodelmay assumeseveraltformsde-pendingontransientstage,primarysidecharacteristics,etc.Modelingphiloso-phyBest-estimateConservativeESFdelays,freevolumecalcula-tions,othermodelcharacteristics arebest-estimatefortheMELCOR modelbutaregenerallyconserva-tivefortheCONTEMPTmodelCodeexecutionOnce-through,coupledrunfromstartofthetransientto conclusionCanbeaniterativeprocessconsistingofinitialruns,sensi-tivityruns,con"rmatoryruns, etc.ThereisnoneedforacollectionorsuccessionofrunsforMEL-COR/RELAP.Undercertaincir-cumstanceswithCONTEMPT,the usermustperformseveralruns toascertainset-points,switchover times,etc.CodeelementsControlvolumes,"owpaths,heatstructures,engineeredsafetyfeatures,controllogicControlvolumes,heatsinks,engineeredsafetyfeatures,con-trollogicCONTEMPThasno"owpathssinceitisasingle-volumemodel.Bothmodelshavecontrolvolumes, heatsinks/structures,andengi-neeredsafetyfeatures.Detailsof thecodeelements EngineeredSafetyFeaturesFancoolers,spraysFancoolers,spraysBothcodesmodelfancoolersandsprayswithsomecorrela-tionorphysicsmodel(notidenti-calones).Actuationset-pointsare basedonsetsofassump-tions.Again,best-estimatescenar-iosareusedforMELCORand conservativescenariosareusedfor

CONTEMPT.ContainmentheatremovalNeglectheatlossthroughcon-tainmentwalls,noCSSorRHR heatexchangermodeling(han-dledinRELAP5-3D)Includeheatlosstoenviron-ment,accountforCSS/RHR heatexchangersandpumpsin

CONTEMPTBecauseCONTEMPTisnotcoupledinrealproblemtimeto anothercodethatmodelsthe RHRheatexchangers,CSSheat exchangers,anddetailsofLH-SI/HHSI,theseelementsmustbe modeled.RELAP5-3DhandlestheseaspectsofthecalculationintheMELCOR/RELAP5-3D coupledrun.Heatsinks/con-densationMELCORbuilt-incorrelationsforbothatmosphereandpool heattransfercotcalcu-lations.Concretecontainmentwallsaremodeledwithoutthesteelliner.Uchidaand/orTagamicorrela-tionsused.Steellinersincluded oncontainmentwallswithair gapbetweenlinerandconcrete.Constantheattransfercocientwithpool.Condensationheattransferistreatedtlyandheatsinks havetcharacteristics.

Liquidpoolheattransferiscal-culatedinternallybyMELCORbutassumedintheCONTEMPTmodel.Sumppooltreat-mentNodecayheatadded.Massandenergysubtractedfromthe poolbasedonRELAP5-3Din-

structionsOnly1largepoolforwholecontainment,perhapsnotin-tendedtocapturethetruebe-haviorofthesumppool.Decay energyaddeddirectlytopoolinrecirculationphase.Thelarge,lumpedpoolofCON-TEMPTvs.thesmaller,annular sub-compartmentpoolofMELCORPipebreak mass/energy

sourceCommunicatedfromRELAP5-3Dviacouplinginterfaceas problemtimeprogresses.The sourceissplitbyMELCOR intopartliquidwater,part steam,andpart"fog"TakenfromRELAPorRE-TRAN,butnotcommunicated inrealproblemtime.All mass/energyaddedexclusively totheatmosphereduringblow-downAllmass/energytoatmosphereinCONTEMPTvs.splitbetweenat-mosphere/poolinMELCORSummaryComparisonofMainParameterValuesThemainnumericalinputparameterscontrollingtheinitialconditionsandboundaryconditionsfortimingandactuation,etc.,betweenRELAP5/MELCOR andCONTEMPTaresummarizedinthefollowingtable.Tuesday1 stMarch,2016:19:32,Page195of393 DRAFTPART2.RAIRESPONSES(ROUND1)CONTEMPTValueRELAP5-3D/MELCORValue Initial Condi-tionsSinglecompartmentfreevolume3.3E+6ft3Sumoverallcompart-ments3329332.0ft3Initialcontainmenttemperature114FInitialatmospheretemperature119.93FInitialcontainment pressure14.5psia(maxT)or15.1psia(maxP)Initialcontainment pressure14.94psiaInitialrelativehumid-ity20%Initialrelativehumid-ity,partialpressureof watervapor70%/1.184psiaInitialRWSTtemper-ature130FInitialRWSTtemper-ature85F EngineeredSafety FeaturesSpraysetpoint(HI-3)12.0psigSpraypressureset-point9.5psigSprayactuationtimesDependsontimeofHI-3trips:0-15.5s,delay=82.6s15.5-29s,delay=

96.1s29-40.5s,delay=

107.6s40.5-52.0s,delay

=119.1s>52.0s,delay=(HI-3time)+69.1sSprayactuationtimes15sdelayaftersetpoint,linearramptofull"owFancoolersetpoint (HI-1)5.5psigFancoolerpressuresetpoint3.0psigFancooleractuation times38sdelayafterHI-1signal tripsFancooleractuation times15sdelayaftersetpoint MaterialProper-tiesThermalconductivityConcrete-0.8BTU/hr*ft*FStainless Steel-9.4BTU/hr*ft*FThermalconductivityConcrete-0.54BTU/ft*hr*FStainlessSteel-f(T),variesSpeci"cheatcapacityConcrete-0.208BTU/lbm*FStainless Steel-0.111BTU/lbm*FSpeci"cheatcapacityConcrete-0.20BTU/lbm*FStainlessSteel-f(T),variesDensityConcrete-144lbm/ft3StainlessSteel-488lb-

m/ft3DensityConcrete-144lbm/ft3Stain-lessSteel-495lbm/ft3 References

1.STPCalculationNC07032,ContainmentLOCAPressure/TemperatureAnalysis,STI33686837.2.NUREG/CR3716,CONTEMPT4/MOD4AMulticompartmentCon-tainmentSystemAnalysisProgram3.NUREG/CR4001,AnImprovementtoCONTEMPT/MOD4Multicom-partmentContainmentSystemAnalysisProgramforIceContainmentAnalysis4.STPGuideLOCAP/TANALYSISUSERGUIDE,Revision4,STI31870431 5.TAMU-GSI-002,MELCORInputDeckCerti"cation:SouthTexasProjectLargeDryContainment,STI336470842.2.3.7SCVB,Question:3c STPResponse:(Item3c,Page62)STPproposestosupplementtheexistingUFSARdescriptionwithade-scriptionoftheriskassessmentofdebrisdescribedinAttachment2to Enclosure3ofReference1tothecoverletter.2.2.3.8SCVB,Question:4a STPResponse:(Item4a,Page62)ThelicensingbasisfortheassessmentoftheeofdebrisisbeingrevisedandthedescriptionoftheriskassessmentwillbedescribedintheSTPUFSAR asdiscussedinthelicenseamendmentrequest,Enclosure3,Attachment2.The resultsoftherisk-informedassessmentdemonstratethatthecontainmentsumps aretlyreliableinsupportoftheContainmentSpraySystem(CSS)such thatthefunctionoftheCSSremainsascurrentlydescribedintheUFSARwith respecttodoseassessment.Tuesday1 stMarch,2016:19:32,Page196of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.3.9SCVB,Question:4bSTPResponse:(Item4b,Page63)Thecurrentlicensingbasiscontainmentatmospherecleanupmethoddoesnotspeci"callyaddresstheofdebrisontheContainmentSpraySystem (CSS).FromthestandpointofGDC-41andCSS,theparameterofinterestis availableNPSHintherecirculationmode.Otherthantheevaluationofthe debrisonCSS,theriskassessmentdoesnotevaluatecontainmentatmo-spherecleanup.Theriskassessmentshowsthattheprobabilityofdebris availableNPSHforCSSsuchthattheCSSwillnotperformitsfunctionisvery smallinaccordancewiththeRG1.174acceptancecriteria.2.2.3.10SCVB,Question:4c STPResponse:(Item4c,Page63)STPproposestosupplementtheexistingUFSARdescriptionwiththeriskassessmentofdebrisdescribedinthelicenseamendmentrequest,Enclo-sure3,Attachment2.2.2.3.11SCVB,Question:5 STPResponse:(Item5,Page63)AsdiscussedintheresponsetoSCVBRAI3.b,above,STPisnotproposingtoapplytheRG1.74risk-informedapproachtorevisethelicensingbasisfor containmentdesigndescribedintheUFSAR.Thecontainmentpressuresand temperaturescalculatedintherisk-informedanalysisdependonthespeci"c casesevaluatedandaretime-dependent;however,thevaluesthatcorrespond tothecurrentUFSARdesignbasisconditionsarecomparabletothecurrent designandlicensingbasisresults.Theresultsoftheanalysisshowthatthe probabilitythatdebriswillpreventtheEmergencyCoreCoolingSystem(ECCS) andContainmentSpraySystem(CSS)fromperformingtheirrequiredfunction isverysmallinaccordancewiththecriteriaofRG1.174andthosesystemsare consideredabletoperformtheirfunctionsasdescribedintheUFSAR.Thereis nochangeintheirdesignbasiswithrespecttocontainmentdesign.2.2.3.12SCVB,Question:6 STPResponse:(Item6,Page63)SeetheresponsetoSCVB-RAI5,above.2.2.3.13SCVB,Question:7 STPResponse:(Item7,Page63)TheriskassessmentislimitedtoevaluatingtheofdebrisonEmergencyCoreCoolingSystem(ECCS)andContainmentSpraySystem(CSS)inthe recirculationmode.Asdiscussedintheresponsesabove,itisnotproposedto replacethecurrentdesignbasiscontainmentanalyses.Itisnotproposedasa changetotheECCSevaluationmodelandSTPdoesnotproposetoapplyit toshowthat10CFR50.46(b)(1)limitsaremetforpeakcladdingtemperature.

Theresultsoftheanalysisshowthattheprobabilitythatdebriswillpreventthe ECCSfromperformingitsrequiredfunctionisverysmallinaccordancewiththe criteriaofRG1.174andthesystemisconsideredabletoperformitsfunctionTuesday1 stMarch,2016:19:32,Page197of393 DRAFTPART2.RAIRESPONSES(ROUND1)asdescribedintheUFSAR.ThereisnochangeintheECCSdesignbasiswithrespecttocontainmentpressure.2.2.3.14SCVB,Question:8 STPResponse:(Item8,Page63)Earlyindevelopmentoftherisk-informedapproachforGSI-191investiga-tion,extremecoreblockagescenariosinvestigationsforcoreandReactorCoolant System(RCS)responsewereunavailableintheacademicliterature.STPthere-foreundertookbasicresearchtounderstandsuchcoreandRCSresponsesin theoreticallyextremescenarios.Themainideabehindthesesimulationswas toinvestigateandunderstand,assumingthat"owblockagecouldoccur,which extremetheoreticalscenarioswouldgotosuccessandwhichwouldleadtofail-ure.Resultsofthestudiesperformedhavesincebeenpublishedinpeer-reviewed

literature.Scenariosweredevelopedassuminginstantaneousblockageatthetimeofrecirculationswitchoverforhotandcoldlegbreaklocationsandsize(small, medium,andlarge)toaccountfort"owpatternsandRCSresponseas describedintheLAR.Thebreaksizeswerechosenathighvaluesforsmall, medium,andlargeSTPLOCAcategories.Allthecasesassumedthatoneofthe EmergencyCoreCoolingSystem(ECCS)trainsisinthebrokenleg(STPLoop B)therebyminimizingeeinjection"owtothecore.Thismatrixresultsin sixscenarios.TheprimaryobjectivewastostudythecoreandRCSresponseforthemainbreaklocationsandsizestogainunderstandingoftheseverityofsuchresponses underextremeconditionsofblockage.Because"owfromthesumpwouldtake a"niteamountoftimetocarryanydebristothecore,itisclearthatsuch instantaneousblockÂagecouldonlyberealizedintheory.Blockage,shouldit actuallyoccur,wouldrequiresomeamountoftimetobuildup.Thescenarios selectedthereforerepÂresentoutcomesfortheoreticalextremes.Theresultsare usefulforsuccesscriteriaintheProbabilisticRiskAssessment(PRA)andfor safetymarginaskedforinRG1.174.Thatis,byinvestigatingtheseextreme theoreticalscenarios,wecouldseethatthevastmajorityofhypothesizedLOCA scenarioswouldgotosuccess.STPinvestigatedadditionalmarginalcasesas furtherdescribedintheLAREnclosure5(Volume6.2,page117,Item5.a.14),

whereeithertherewas"owthroughthebbypassregion(with-outcreditforLOCAholesintheorthroughasmallopening(onefuel channel,eitherperipheralorcenter)inthecore.2.2.3.15SCVB,Question:9a STPResponse:(Item9a,Page63)Thelicenseamendmentrequest,Enclosure2-2,Section1identi"estheEmer-gencyCoreCoolingSystem(ECCS)astheonlysystemforwhichtheproposed exÂemptiontoGDC35wouldapply.TheECCSistheonlysystemcredited formeetingGDC-35thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftheriskassessmentprovidedintheSTPlicensing

application.Tuesday1 stMarch,2016:19:32,Page198of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.3.16SCVB,Question:9bSTPResponse:(Item9b,Page63)ThesecondparagraphofGDC-35prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-35utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailurein 10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethatcould resultinthefailureofmultiplecomponents.Theriskassessmentdemonstrates thechangeincoredamageorlargeearlyreleasefrequencyfromthedebris isverylowinaccordancewiththeguidanceofRG1.174.2.2.4SNPBResponses 2.2.4.1SNPB,Question:1a STPResponse:(Item1a,Page64)Thevolumeofthelowerplenumis638.7ft 3.Thevolumeofthecoreis715.1ft 3.Thevolumeoftheupperplenumbelowthebottomelevationofthehotlegis 520.51ft 3.Diagramsdisplayingthesevolumesandtheirrespectiveelevationsareshown below.

Reference:

1.T.Crook,A.Franklin,J.Scherr,R.Vaghetto,A.Vanni,andY.Hassan, SouthTexasProjectPowerPlantRETRAN-RELAP5-3DConversionTables, July2013.Tuesday1 stMarch,2016:19:32,Page199of393 DRAFTPART2.RAIRESPONSES(ROUND1)Tuesday1 stMarch,2016:19:32,Page200of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.2SNPB,Question:1bSTPResponse:(Item1b,Page64)NuclearSteamSupplySystem(NSSS)parametersareprovidedhereforsteadystatefullpoweroperationundernominalconditions.Toexaminethe pressurelossesateachsectionoftheloop,individualpressuresweretakenfrom theRELAP5-3Dsteady-statesimulation(1).Figure1showstheRELAP5-3D nodalizationoftheplantfromRef.1.forreferenceinthefollowingtables.Figure1:RELAP5-3DNodalizationDiagramofthePrimarySystem(AccumulatornotShown)Table1:Steady-StatePlantOperatingConditionsParameterSteadyStateConditions(units)LoopMassFlowRate10108.453(lbÂm/s)UpperPlenumBypassFraction2.080(%)

CoreFlowRate36998.386(lbm/s)Core/VesselInletTemperature560.977FAverageCoreOutletTemperature626.354FReducedFlowAreaDuetoSGtubePlugging0%(NoSGplugging)Table3showsthe"owareas,hydraulicdiameters,andk-losscotsattlocationsoftheprimarysystem,identi"edasjunctionsbetweennodes incolumnRELAP5-3DJunctionID.ThelockedrotorReactorCoolantPump(RCP)k-factor,calculatedwiththeRELAP5-3Dsteady-stateinputmodelisshownbelow:K rotor=5.86

Reference:

1.STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.July2013.Tuesday1 stMarch,2016:19:32,Page201of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2:RELAP5-3DLoopPressuretialsLocationRELAP5-3DNodesIDRELAP5-3DPressureChange(psid)PumpInlet11202-1130150.3095PumpOutlet11301-1160126.0005 VesselInlet11601-501010.6746 Downcomer53501-501014.2771UpperPlenumBypass58501-50101-41.9059Core84501-54501-37.4984 VesselOutlet10001-84501-17.648 HotLeg10402-10001-0.4353 SGPlenumInlet10601-104025.4342 SGU-tubesInlet10801-10601-5.3809 SGU-Tubes10808-10801-15.4235 SGU-TubesOutlet11001-108081.4743 SGPlenumOutlet11202-11001-9.3558 VesselInlettoExit50101-8650138.8255Table3:RELAP5-3DLoopFlowAreasandFrictionalk-lossFactorsLocationRELAP5-3DJunctionIDFlowArea(ft2)JunctionHydraulicDiameter(ft)Forward k-lossReverse k-lossUpperPlenum-HotLegjX21(865-X00)4.58692.416670.11940HotLeg-SGPlenumInletjX05(X04-X06)4.58692.585830.464640.279639SGPlenumInlet-U-tubesjX07(X06-X08)15.29290.05066670.230.491709U-tubes-SGPlenumOutletjX09(X08-X10)15.29290.05066670.4917090.23SGPlenumOut-let-Crossover LegjX11(X10-X12)5.2412.585830.2796390.46464CrossoverLeg-RCPInletX12-X135.2412.5830.0012.09RCPOutlet-ColdLegX13-X144.12472.291672.090.001ColdLeg-Vessel InletjX19(X18-501)4.12472.2916700.1194UpperCorePlate-UpperPlenum845-86551.07640.03650.59150.5915Tuesday1 stMarch,2016:19:32,Page202of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.3SNPB,Question:1cSTPResponse:(Item1c,Page64)RefuelingWaterStorageTank(RWST)(LAREnclosure4-3,Ref.40,Page 6.3-32)Fulltankvolume,gal550,000*Minimumvolume(TechnicalSpeci"cation),gal458,000*

Boronconcentration(asboricacid),ppm2,800-3,000*Volumesincludeunusablevolume.2.2.4.4SNPB,Question:1dSTPResponse:(Item1d,Page64)Unit1-SecondaryMake-UpTank,gal300,000Unit2-SecondaryMake-UpTank,gal300,000 Unit1AuxiliaryFeedwaterStorageTank,TSmin,gal458,000 Unit2AuxiliaryFeedwaterStorageTank,TSmin,gal458,000SecondaryMake-UpTanksprovidenormal,non-safetyrelatedmakeupwatertothesecondaryside.

TheAuxiliaryFeedwaterStorageTankistheTSrequiredsafety-relatedwater sourceusedbytheAuxiliaryFeedwaterSystemtoremoveheatfromtheRCS viathesteamgenerators.2.2.4.5SNPB,Question:1eSTPResponse:(Item1e,Page64)Componentsofthe"ushing"owrateincludethecoldleginjection"owrate,hotleginjection"owrate,andvaporgenerationratethatwereextractedfrom theRELAP5-3D/MELCORsimulationofacoldlegdoubleendedguillotine (DEG)breakscenario,undernominaloperatingconditions.Detailsonthesim-ulationconditionsappliedareavailableinLAREnclosure4-3,Reference5,page 12.TheRELAP5-3Dnodalizationdiagramadoptedforthesimulationisde-pictedinFigure2ofLAREnclosure4-3,Reference5,page7.Thetotalcoldleginjection"owrate,thetotalhotleginjection"owrate,andthecorebrateareplottedinFigureA.Thesethermal-hydraulicpa-rametershavebeenestimatedasfollows:

• Thetotalcoldleginjection"owratewasestimatedasthesumofthecoldleginjection"owratefromeachofthesafetyinjection(SI)trains(sumof mass"owratesofthevalvecomponents149,249and349ofFigure2of LAREnclosure4-3,Reference5,Page7).

• Thetotalhotleginjection"owratewasestimatedasthesumofthehotleginjection"owratefromeachoftheSItrains(sumofmass"owrates ofthevalvecomponents148,248and348ofFigure2ofLAREnclosure 4-3,Reference5,page7).

• Thecorebratewascalculatedasthesumofvaporgenerationrateinallthenodesofthecore(Pipecomponents605and606(LAREnclosure4-3,Reference5,page5),total42nodes).ThevaporgenerationrateineachTuesday1 stMarch,2016:19:32,Page203of393 DRAFTPART2.RAIRESPONSES(ROUND1)nodewasestimatedbymultiplyingthevalueoftheparametervapgenbythevolumeofthenode.FigureA:RateofInjectionParametersacrosstheSimulationTable1:AverageInjectionandVaporGenerationBeforeandAfterSwitchtoSimulta-neousInjectionTimeIntervalColdLegInjection (lbm/s)HotLegInjection (lbm/s)VaporGeneration (lbm/s)15000s-SimultaneousInjection1615.500.00434.91 AfterSimultaneousInjection556.541107.420.75

Reference:

1.RELAP5-3DUsersManual,INEEL-EXT-98-00834.Tuesday1 stMarch,2016:19:32,Page204of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.6SNPB,Question:1fSTPResponse:(Item1f,Page64)HighHeadSafetyInjectionPumps(HHSI)(LAREnclosure4-3,Ref40,Page 6.3-31)Max.(run-out)"owrate,gal/min1,6002.2.4.7SNPB,Question:1gSTPResponse:(Item1g,Page64)TheboricacidstoragetanksarenotapartoftheSTPEmergencyCoreCool-ingSystem(ECCS),(LAREnclosure4-3,Reference40)andarenotconsidered withintheCASAGrandeAnalysis.2.2.4.8SNPB,Question:1hSTPResponse:(Item1h,Page64)TheboricacidstoragetanksarenotapartoftheSTPEmergencyCoreCool-ingSystem(ECCS)(LAREnclosure4-3,Reference40)andarenotconsidered withintheCASAGrandeAnalysis.2.2.4.9SNPB,Question:1iSTPResponse:(Item1i,Page64)ThetimetoemptytheRefuelingWaterStorageTank(RWST)(timetoinitiatethesumpswitchoverprocedure)wascalculatedusingtheRELAP5and MELCORinputmodelsdescribedin(LAREnclosure4-3,Reference5,page5).

Thevaluereportedbelowwascalculatedunderthefollowingconditions:

• Coldlegdoubleendedguillotine(DEG)break(27.5inchbreakinloop3)

• Nominalplantconditions(allSafetyInjection(SI)andContainmentSpray(CS)pumpsoperating)(Seenote)

• UsablevolumeoftheRWST(volumeofthewateruntilthelow-lowlevelalarmisreached)equalto413,735USgal.ThetimetoemptytheRWSTwasestimatedtobe:

TRWST=29.5minNote:Oneofthethreecontainmentspraypumpsmanuallysecuredatthebeginningofthetransient.

Reference:

1.STPMAAP4.04InputFile2.2.4.10SNPB,Question:1jSTPResponse:(Item1j,Page64)ContainmentpressurewascalculatedusingtheMELCORinputmodelde-scribedin(LAREnclosure4-3,Reference5,page8).Thepressurereportedwas calculatedunderthefollowingconditions

• Coldlegdoubleendedguillotine(DEG)break(27.5inchbreakinloop3)

• Nominalplantconditions(allSafetyInjection(SI)andContainmentSpray(CS)pumpsoperating)(LAREnclosure4-3,Reference5,page14)(See

Note)Tuesday1 stMarch,2016:19:32,Page205of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:ContainmentPressure(fromMELCORUpperCompartment)Thepressureofthecontainmentwasextractedasthetotalpressureoftheuppercompartment(node4oftheMELCORcontainmentmodelnodalization diagraminFigure4ofLAREnclosure4-3,Reference5,page9).ThecontainmentpressureresponseduringthetimebetweenthesumpswitchoverandthehotlegswitchoverisplottedinFigureA.Note:Oneofthethreecontainmentspraypumpsmanuallysecuredatthebeginningofthetransient.Tuesday1 stMarch,2016:19:32,Page206of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.11SNPB,Question:1kSTPResponse:(Item1k,Page64)Thesumpboricacidconcentrationovertimewasnotcomputed.However,thesumpboricacidconcentrationistightlycontrolled.Approximately88%of thesumpboricacidconcentrationisprovidedbytheRefuelingWaterStorage Tank(RWST)(between2800and3000ppm)andaccumulators(between2700 and3000ppm).Theremainingcontributiontoboricacidconcentrationcomes fromtheRCSwhichvariesbetween0and3500ppm.

Reference:

1.SouthTexasProjectNuclearOperatingCompany.Westinghouse.CN-CRA-97-094Rev.1.RequiredMassofTSPforLOCASumpSolutionpHAd-justment,November20082.2.4.12SNPB,Question:1l STPResponse:(Item1l,Page64)TheminimumtemperaturefordeterministicLOCAanalysisis50F.Thistemperatureisthedesignrangeminimumforthebuildingambienttemperature.

Reference:

1.SouthTexasProjectElectricGeneratingStation.MABHVACDesignBasisDocument5V109VB00110.Rev.3.TableT-8.Page266.2.2.4.13SNPB,Question:1m STPResponse:(Item1m,Page64)TheHighHeadSafetyInjection(HHSI)dischargetemperatureandtheLowHeadSafetyInjection(LHSI)dischargetemperaturewereextractedfromthe simulationresultsofa27.5inchcoldlegdouble-endedguillotine(DEG)break performedwithRELAP5-3D/MELCOR.InformationontheRELAP5and MELCORsimulationconditionsarereportedintheSumpSensitivityAnaly-sis(LAREnclosure.4-3,Reference.5,page.14)fornominalconditions.TheRELAP5nodalizationdiagramoftheEmergencyCoreCoolingSystem(ECCS)isdepictedinFigureAtofacilitatetheidenti"cationofthevolumes (nodes)wheretheliquidtemperaturewasread.BasedonthediagramofFigureA,thedischargetemperatureoftheHHSI(time-dependentjunctionx45)isthesameasthesumppooltemperature(tem-peratureoftheliquidinthetime-dependentvolumex91)becausenoheatstruc-turesweremodeledalongtheHHSI"owpath.ThedischargetemperatureoftheLHSI(time-dependentjunctionx46)wasreadastheliquidtemperatureattheexitofthepipecomponentx47,simulating theprimarysideoftheResidualHeatRemoval(RHR)heatexchanger.Theinjectiontemperature,resultingfrommixingoftheliquid"owsfromtheHHSIandLHSI,wasreadasthetemperatureoftheliquidinthemixingbranch (nodex60).FigureBshowsthedischargetemperatureoftheHHSI,thedischargetem-peratureoftheLHSI,andthetemperatureofthemixedliquidinjectedinthe primarysystemduringthetimebetweenthesumpswitchoverandthehotleg switchover.Tuesday1 stMarch,2016:19:32,Page207of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:RELAP5-3DSafetyInjectionNodalizationDiagram(X=loopnumber=2,3,or4)(LAREnc.4-3,Ref.5,Page7)2.2.4.14SNPB,Question:2aSTPResponse:(Item2a,Page64)SuctionLegDataInnerDiameter31CenterLineEl.225-5/16 BottomEL.ofID21.151 TopEL.ofID23.73(SeeresponsetoSNPB-RAI-2bforcoldleginformation).2.2.4.15SNPB,Question:2bSTPResponse:(Item2b,Page64)2.2.4.16SNPB,Question:2cSTPResponse:(Item2c,Page64)TopElevationofCore,ft26.796HeightofCore,ft14(SeetheresponsetoSNPB-RAI-1a)2.2.4.17SNPB,Question:2dSTPResponse:(Item2d,Page64)BottomElevationofDowncomer,ft10.81 (SeetheresponsetoSNPBRAI1a)Tuesday1 stMarch,2016:19:32,Page208of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureB:SafetyInjectionTemperature(FromSumpSwitchovertoHotLegSwitchover)ColdLeg,RCPDischargeInnerDiameter27.5CenterLineEl.323 BottomEL.ofID311.25 TopEL.ofID334.752.2.4.18SNPB,Question:3STPResponse:(Item3,Page64)Themaximumcoreaxial(AOs)forLOCAanalysesmustmeetthere-quirementsofthereloadsafetyanalysischecklist(RSAC)Item3.9perSTPNOC procedure0PEP01-ZE-0003"CoreReloadDesignProcess."TheRSACrequires aminimumAOof-20%andamaximumAOof15%forLOCA.Thecoresare designedtomeetTechnicalSpeci"cationlimitsofFxyandFn?HPowershapesarenotacoredesignparameter.AlthoughnotaSTPdesignbasis,basedonthedesignlimitsonAO,shapes(maximumalloweddesignLOCA AO)canbedevelopedforbottomandtopskewedaxialpowershapesusingthe followingconstraints:1.Power=0atbottomandtopofcore(nopowergenerationoutsideofcore) 2.Theintegralfrom0to0.5is1.2timesgreaterthantheintegralfrom0.5to1.0(bottom-skewed).Theintegralfrom0.5to1.0is1.15timesgreater thantheintegralfrom0to0.5(top-skewed).3.Theslopeismaximum(in"nite)atx=0(bottom-skewed),in"niteatx=1.0(top-skewed)4.Theslopeatx=1.0isnegative(bottom-skewed),slopeat0ispositive(top-skewed)Tuesday1 stMarch,2016:19:32,Page209of393 DRAFTPART2.RAIRESPONSES(ROUND1)5.Nopowersharing(fxyiseverywhere1.0),allchannelshaveexactlythesameaxialpro"le.Theparametersabovearechosentomaximizethepoweratthelowest(orhighestfortop-skewed)bysettingtheslopemaximumatx=0orx=1.0.Also,uniform radialpeakingwouldminimizechannel-to-channelmixing.Theresultingfunctionforbottom-skewedpro"lesis:

f (x)=11.09564432(x 0.80075524)(1x).Theresultingfunctionforbottom-skewedpro"lesis:

f (x)=5.2542(x 0.846098516)(1x)[shapehastobere"ectedsothatxrunsfrom1.0to0.0]Aconceptualillustrationofthefunctionsisshownbelow.TheactualminimumandmaximumAOsmeasuredforseveralcorecycleshasbeenwellwithinthecoredesignrequirements.STPNOCGuidelineREM-2CorePerformanceTrendingProgramrequiresmeasuredaxialtobe plottedforoverthecycleforUnits1and2.TheminimummeasuredAOforwas

-7.5%inUnit2andthemaximummeasuredAOwas6%inUnit1.2.2.4.19SNPB,Question:5 STPResponse:(Item5,Page65)Thesumpboricacidconcentrationovertimewasnotcomputed.However,thesumpboricacidconcentrationisrelativelyconstantastheconcentrationis tightlycontrolled.Approximately88%ofthesumpboricacidconcentrationis providedbytheRefuelingWaterStorageTank(RWST)(2800and3000ppm) andaccumulators(2700and3000ppm).Theremainingcontributiontoboric acidconcentrationcomesfromtheReactorCoolantSystem(RCS)whichvaries between0and3500ppm.TheRCScontributiontothesumpboricacidconcen-trationhaslittle

Reference:

1.SouthTexasProjectNuclearOperatingCompany.Westinghouse.CN-CRA-97-094Rev.1.RequiredMassofTSPforLOCASumpSolutionpHAd-justment.November2008.Tuesday1 stMarch,2016:19:32,Page210of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5SSIBResponses2.2.5.1SSIB,Transport:Question12 STPResponse:(Item12,Page70)Item5.a.4ofLAREnclosure5(Vol.6.2)wasaddedassupplementaryin-formationdescribingdetailsandassumptionsofthesupportingdebristransport calculation.Adescriptionofthehomogenouspoolmixingassumptionusedin theSTPCASAGrandeevaluationisprovidedintheresponsetoSSIBRAI11C inSTPlettertoNRCdatedMay22,2014,NOC-AE-14003103(ML14149A434).Becausehomogeneousmixingofall"neandsmalldebrisisassumed,thestatementoflocalretentionmadeinVol.6.2hasnoimpactondebristransport.

Debristransportdirectlytothesumpsunderpotentialsheeting"owduringpool "llisassessedasafractionofthedebristhatiscalculatedtoresideonthe"oor immediatelyafterthebreak.Similarly,theassumptionofhomogeneousmixing forall"neandsmalldebrisisnotbythedebrislocationfollowingpool

"ll.2.2.5.2SSIB,HeadLossandChemicalBump-up:Question 25aSTPResponse:(Item25a,Page76)Assumption7.fisaccurate.Thereisagapof2inchesfromthebottomofthestrainertothe"oor.Initially,thestraineraccumulates"beruniformly, includingthe2inchgap.Oncetheloadingtransitionstothecircumscribedarea andthe2-inchgapis"lled,(itphysicallycannolongeraccumulate"ber),the remainderofthestrainercontinuestoaccumulate"berinauniformmanner.

TheexistingSTPstrainerlayoutanddesignensuresthattheassumptionof uniformaccumulationofthetransporteddebrisoverallactiveportionsofthe strainerisvalid.Equations42and43(LAREnclosure4-3,page180)areusedtocalculatetheincrementalthicknessincreaseandcorrespondingdebrissurfacearea.Once the2-inchgapis"lled,"owisconsideredtoberestrictedandEquations42and 43calculateuniformdebrisaccumulationonallsidesofthestrainerexceptthe bottomwhere"owissettozero.Thisdecreasein"owsurfaceareainitially increasestheheadlosscomparedtoprevioustimestepswhenconsideringEqua-tion33(LAREnclosure4-3,page175).Assumption7.f(LAREnclosure4-3, page79)isusedtocalculatetheincrementaldebrisbedthicknessincreaseand debris("ow)areasusedintheheadlosscalculationsaccordingtoEquations40 through43(LAREnclosure4-3,page180).Totalstrainervolumetric"owrate dividedbyavailable"owareadeterminesapproachvelocityusedinthehead-loss

correlation.CASAGrandedoesnotcomparethedebrisheightonthetopofthestrainertothepooldepth.Intherareconditionthatthebedcanexceedthisheight,the currentevaluationallows"owareatoincreaseunrealisticallyatthetopofthe strainer.Althoughuncon"nedbedgrowthabovethepoolisnon-conservative, itwasstatedinAssumption7.fthatthisisanunlikelyoccurrence.Assumption 7.fcanbevalidatedbycomparingtheminimumpoolheight(inputdistribution lowerbound)andcorresponding"beraccumulationnecessarytoexceedthepool heighttotheprobabilitydistributionofdebrisvolume(seeresponsetoSSIB-Tuesday1 stMarch,2016:19:32,Page211of393 DRAFTPART2.RAIRESPONSES(ROUND1)RAI-26d).2.2.5.3SSIB,HeadLossandChemicalBump-up:Question 25bSTPResponse:(Item25b,Page76)ThisdoesnotAssumption7.e.Assumptions7.eand7.fareconsistentinthathomogeneouslymixeddebriswillaccumulateuniformlyontheas-designed STPstrainer.Initially,thestraineraccumulatesthehomogeneouslymixed"beruniformly,includingthe2-inchgap.Oncethe2-inchgapis"lled,(itphysicallycanno longeraccumulate"ber),theremainderofthestrainercontinuestoaccumulate "berinauniformmanner,andthe"owareaisadjustedtoaccountforlossof "owthroughthebottom.Becausethereisno"owsimulatedthroughthebottom ofthestrainerafterthetwo-inchgapis"lled,debriswillbehomogenouslymixed onallremainingsidesofthestrainerthatdosupport"ow.TheexistingSTPstrainerlayoutanddesignensuresthattheassumptionofuniformaccumulationofthetransporteddebrisoverallactiveportionsofthe strainerisvalid.2.2.5.4SSIB,HeadLossandChemicalBump-up:Question 26aSTPResponse:(Item26a,Page76)Yes,thestrainerloadingtableofSection5.6(LAREnclosure4-3,page181,Table5.6.3)includesareascalculatedforalldebrisloadingsincludingthetran-sitionfromthinbedstocircumscribedloads.Thistablewasusedtodetermineif thethin-bedloadingcriterionwasexceeded.Toevaluatesurfaceareasofdebris bedstransitioningfromthinbedtocircumscribed,thedebriswaslinearlyinter-polatedusingthearrivingdebrisvolumecalculatedusingmanufactureddensity.

Forthinbeds,theinterpolateddebrisvolumerangewasbetweenthe0and81.79

ft 3withacorrespondingarearangeof1,818.5and419.0ft2,respectivelyfromTable5.6.3(LAREnclosure4-3,page181).2.2.5.5SSIB,HeadLossandChemicalBump-up:Question 26bSTPResponse:(Item26b,Page76)TheincreaseindensityfromthemanufacturedvalueisnotaccountedforintheStrainerloadingtable(LAREnclosure4-3,page181).Thistableis basedonthicknessalone,andreportsassociatedareasandvolumes.Debriscom-pressionisaccountedforbythehead-losscorrelationthatprovidesane thicknessthatcanbeusedtointerpolatethetableto"ndesurfacearea.2.2.5.6SSIB,HeadLossandChemicalBump-up:Question 26cSTPResponse:(Item26c,Page76)Thegeneralarrangementofthestrainersdoesshowthatonesideofall3strainertrainsfacestheoutercontainmentwall,andthebottomsidefacesthe containment"oor.Oneofthestrainertrainsadditionallyhasastructuralwall approximately2to3feetaway.VisualinspectionoftheEmergencyCoreCooling System(ECCS)strainerperformancetesting(LAREnclosure4-3,Reference53,Tuesday1 stMarch,2016:19:32,Page212of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure8-6,Figure8-7,page47)showsthatevenincon"nedspaces(test"ume)thestrainersloadevenly.The"oorrepresentsanobstructionthatpreventscircumscribedloadingfromexceedingthe2-in.gapthatexistsbetweenthe"oorandthelowestedgeofthe strainers.Whenthisgapis"lled,thelowersurfaceisnolongeravailablefor "ow.Thestrainerloadingtablethenassumesthatdebrisaccumulationcontinues uniformlyinallunimpededdirections.2.2.5.7SSIB,HeadLossandChemicalBump-up:Question 26dSTPResponse:(Item26d,Page76)CASAGrandedoesnotcomparethedebrisheightontopofthestrainertothepooldepth.Intherareconditionthatthebedcanexceedthisheight, thecurrentimplementationallows"owareatoincreaseunrealisticallyatthe topofthestrainer.Althoughuncon"nedbedgrowthabovethepoolisnon-conservative,itwasstatedinAssumption7.fthatthisisanunlikelyoccurrence (LAREnclosure,4-3,page79).Assumption7.fisvalidatedbycomparingthe minimumpoolheight(inputdistributionlowerbound)andcorresponding"ber accumulationnecessarytoexceedthepoolheighttotheprobabilitydistribution ofdebrisvolume.Aminimumcontainmentpoolvolumeof39,533ft 3(inputdistributionlowerbound),andpoolareaof12,301ft 2wereusedintheCASAGrandeevaluation(LAREnclosure4-3,page45).Dividingthepoolminimumvolumebythepool areayieldstheminimumpossiblesampledpoollevelof3.2feetor38.6inches.

Subtractingtheheightofthetopofthestrainer28.5inches(LAREnclosure4-3, page63)fromtheminimumpoollevelgivestheminimumthicknessneededfor thedebristoreachthesurfaceofthepool(10inchesof"beraccumulation).This thicknessequatestoavolumeof328ft3necessarytoaccumulateonthestrainer tomeetorsurpasstheminimumpoollevelwheninterpolatedfromTable5.6.3.Complementarycumulativedensitydistributionsofthetotal"beramount(beforetransportfractionsareapplied)areillustratedinFigureAformany LatinHypercubeSampling(LHS)replicates,takenoverthefullbreaksizerange (SBLOCA,MBLOCA,andLBLOCA),usingtheZoneofIn"uence(ZOI)sizes describedinTable2.2.0(LAREnclosure4-3,page56).Thisquantityincludes latent"berandallZOIdestroyed"brousinsulationquantities.FigureBshows thatonacloserscaletheconditionalprobabilityofexceeding328ft 3of"brousdebrisislessthan10

-14.Tuesday1 stMarch,2016:19:32,Page213of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:CCDFofLDFGdebrisgenerated,beforetransportFigureB:CCDFofLDFGpresentandgenerated,beforetransport(zoomedin)Tuesday1 stMarch,2016:19:32,Page214of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.8SSIB,HeadLossandChemicalBump-up:Question 26eSTPResponse:(Item26e,Page76)Theinterstitialgapsofasinglestrainerare"lled(0.5inchdebristhickness)whenthevolumeofdebrismeetsorexceeds81.79ft3(LAREnclosure4-3, Table5.6.3).Complementarycumulativedensitydistributionsofthetotal"ber amount(beforetransportfractionsareapplied)areillustratedinFigureAfor manyLatinHypercubeSampling(LHS)replicatestakenoverthefullbreak sizerange(SBLOCA,MBLOCA,andLBLOCA),usingtheZoneofIn"uence (ZOI)sizesdescribedinTable2.2.0(LAREnclosure4-3,page56).Thisquantity includeslatent"berandallZOIdestroyed"brousinsulationquantities.Figure Bshowsonacloserscalethattheconditionalprobabilityofexceeding81.79ft 3of"brousdebrisislessthan10-14.Adatatickhasbeenaddedtothe"gurenear the81.79ft 3debrisvolume.NotethatLowDensityFiberglass(LDFG)volumesinthese"guresrepresentgenerateddebrisvolumes.Correspondingdebrisvalues thatreachthestraineraresmaller,sotheassociatedprobabilityofreachingthe circumscribedloadisalsosmaller.FigureA:CCDFofLDFGdebrisgenerated,beforetransportTuesday1 stMarch,2016:19:32,Page215of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureB:CCDFofLDFGpresentandgenerated,beforetransport(zoomedin)Tuesday1 stMarch,2016:19:32,Page216of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.9SSIB,HeadLossandChemicalBump-up:Question 26fSTPResponse:(Item26f,Page76)Asthedebris"llstheinterstitialvolumeofthestrainersthe"owareade-creasesfromthecleanstrainerareatothelimitinglowest"owareaofthecir-cumscribedfacessurroundingthestrainers.Asthe"owareadecreases,the"uid approachvelocity(U)increases(LAREnclosure4-3,Equation34,page176).

Thisincreasein"uidapproachvelocity(U)directlyincreasesthecalculated headloss(LAREnclosure4-3,Equation33,page175).2.2.5.10SSIB,NPSHandDegasi"cation:Question30 STPResponse:(Item30,Page77)No,thedegasi"cationcalculationdoesnotcreditcontainmentaccidentpres-sure.Inalldegasi"cationcalculations,bulksumpwatertemperaturesbelow212Fassumeatmosphericpressure(14.7psia).Atsumptemperaturesabove212F,thecontainmentpressureisassumedtobeequaltothevaporpressureofthe sumpwater.Theoveralltemperaturerangeusedforthedegasi"cationcalculation(s)is 102.5Fto177.5FforSBLOCAandMBLOCA.TheoveralltemperaturerangeforLBLOCAcalculationsis86.0Fto255.8FforLBLOCA.Therangewasdeterminedbybreaksizebasisandisbasedontime-dependentchangesinthe bulksumpwatertemperaturefromthetimeofrecirculationthroughsteady-statelong-termcooling(LAREnclosure4-3,Reference5).2.2.5.11SSIB,NPSHandDegasi"cation:Question31 STPResponse:(Item31,Page77)Reference56,TDI-6005-07,Vortex,AirIngestion&VoidFractionSouthTexasProjectUnits1&2.Revision3:November24,2008,evaluatesthepossi-bilityofthecollectionofgasbubblesintheSTPstrainer.WhileReference56 concludesthatthereisnoairingestionorvoidformation,CASAGrandecalcu-latesavoidfractionandappliestheresultsinthecalculationEmergencyCore CoolingSystem(ECCS)andContainmentSpraySystem(CSS)pumpNPSHr.AsstatedinSection2.2.28,theacceptancecriterionforasteady-stategasvoidfractionatthepumpsuctioninletis2%.CASAGrandeconservatively assumesthatanyvoidformedatthesumpstrainerisfullytransportedtothe ECCSorCSSpumpsuction,Assumption8.i.ThegeneraltransportofgasvoidsinthepipingbetweenthestrainerandECCSandCSSpumpsisexplainedinReference58,VTD-G927-0001.Units1 and2AcceptableGasVoidVolumesinECCSandRHRSuctionPiping.2.2.5.12SSIB,NPSHandDegasi"cation:Question32 STPResponse:(Item32,Page78)TheNPSHAmoduleofCASAGrandedoesnotincludecontainmentpressureabovethesaturationpressure,forcoolantvaporpressureconditionsgreaterthan standardatmosphericpressure.Fortemperaturesequivalenttooraboveboiling atstandardatmosphericpressure,thecontainmentpressureissetequaltothe saturationpressureofthe"uidfortheNPSHAcalculation.ForcontainmentTuesday1 stMarch,2016:19:32,Page217of393 DRAFTPART2.RAIRESPONSES(ROUND1)coolantvaporpressuresbelowboiling,thestandardatmosphericpressureof14.7psiisusedasthecontainmentpressure.2.2.5.13SSIB,NPSHandDegasi"cation:Question34 STPResponse:(Item34,Page78)Userenteredminimumandmaximumcontainmentspraysystem(CSS)"owratesareappliedasprobabilitydistributionbounds;thesmall,medium,and largebreakscenarioshavethesamebounds.Foreachsimulatedpipebreak,the probabilityspacebetweentheuserenteredminimumandmaximumsystem"ow ratesarerandomlysampledtodetermineoneindividualCSSpump"owrate forthescenario.TotalCSS"owrateisdeterminedbymultiplyingtherandom pump"owratebythenumberofoperableCSSpumps.CSS"owratesusedintheCASAGrandeevaluationareenteredasprob-abilitydistributionswithequalprobabilitybetweenuserenteredCSSpump minimumandmaximum"owrates.ThemaximumvalueissettotheFLOMAP calculatedaveragedesign"owsfortrainAandBoperationduringrecirculation (LAREnclosure4-3Reference42,pageA-39).Valuesotherthanthemaximumareappropriatebecausetheboundingmin-imum"owrates,usedasinputs,wereselectedfromsimulatedprobableevents (LAREnclosure4-3,Reference42,pageA-40)foreachoperable-trainstate(i.e.

3,2,or1trainoperable).CASAGrandeusesthehighertwo-trains-operation "owrates(LAREnclosure4-3,Table2.2.15,page54)foralleventswithtwoor threetrainsinoperation(Cases01,09,22and26).Eventswithonetrainopera-tion(Case43)usedtheirrespectiveminimumandmaximumvaluesfromTable 2.2.15(LAREnclosure4-3,page54)toboundtheirprobabilitydistribution.2.2.5.14SSIB,NPSHandDegasi"cation:Question35 STPResponse:(Item35,Page78)Thedoubleendedguillotinebreak(DEGB)valuescomputedbyEquation22ofLAREnclosure4-3(Section5.3.1,Page125)areusedonlytoassignDEGB breakstoaLOCAcategory(S,M,L).Foradoubleendedguillotinebreak,thebreakexitdiameter(D e))isequaltotheinnerdiameter(D i))ofthepipe.ADEGBwithfullseparationresultsintwojets(onefromeachrupturedsideofthepipe).Thus,thereareconceptually twobreakareasandtwobreakvolumes.Theequivalentdiameter(D DEGB)isdeterminedbydoublingthecrosssectionalareaofthebrokenpipeand"nding singleequivalentdiametertorepresentthetotalarea:

ADEGB=2 2 4 2DEGB 4=2 2 4DDEGB=2 D i2.2.5.15SSIB,In-VesselandBoricAcidPrecipitation:Question37STPResponse:(Item37,Page79)Tuesday1 stMarch,2016:19:32,Page218of393 DRAFTPART2.RAIRESPONSES(ROUND1)7.5g/fuelassembly(FA)of"berischosenasathresholdofconcernforboricacidprecipitation(BAP)basedonpreviousresults(LAREnclosure4-3, Reference[62])thatshowedverylittleheadlosswhen15g/FAwithafullamount ofchemicalprecipitateswereappliedduringhotlegbreak"owconditions.Witha debrisloadof7.5g/FA,thecoreisexpectedtoremainfullofwaterduringacold legbreak(CLB)eventhoughthereisnoopportunityforbypass"owcreditedin theanalysis.However,duringaCLB,attheselowdebrisamounts(7.5g/FA),

STPwouldhavesigni"cant"owthroughbypasspathways(LOCAholesandover thetopofthecorefrombypassregion)asdescribedintheLAR Enclosure4-1,Section2.1.2.LAREnclosure4-1,Section2.1.2describesthermal hydraulicanalysisofextremescenariosthatshowthecorewouldcontinuetobe suppliedwithadequate"owsuchthatcoolingispreserved,andthecorewould bere"oodedearlyinthetransient(ADAMSAccessionNo.ML14029A533).The7.5g/FAthresholdisappliedundertheassumptionoffulldebrisdepo-sitiononthefuelandtakesnocreditfordebristhatmayactuallydepositinthe bypass.TheCASAGrandeanalysisrecordsascenariofailure wheneveranequivalentinventoryof7.5g/FAentersthecore.STPfuelassem-bliesaredesignedwithasigni"cantgapbelowthebottomtieplatethatprovides alarge"owplenumbetweenthebottomoftheactivefuelandthetopofthe bottomcoreplate.The"ow-channeltobregionhasalargegap (approximately2inches)aroundtheentirecoreperipherythatisnotcredited forpossibledebrisretentionorforallowinglowconcentration"owtocirculate thoughthebypassregionthroughtheLossofCoolantAccident(LOCA)holes oroverthetopofthecore.STPhasshownthechemicalcontributiontoheadlossisinsigni"cantpriortohotlegswitchover(about6hours).BasedontheSTPreactordesign,basedon boundingexperimentalresultsfromboththeworkdoneinsupportofLAREn-closure4-3,page82of248,andfromReference(1),andbasedonboundingther-malhydraulicsimulationresultsforblockage,itisreasonabletouse7.5g/FA, de"nedbytestsusingaconservativechemicalload,asathresholdofconcern forBAP.Notethatthislimitisappliedtoallscenariosatalltimesregardless ofrealisticchemicalloadingandisthereforeconservativeeventhoughhigher thresholdscouldbeconsidered,particularlyearlyinthescenario.Althoughthe core-"berboronprecipitationthresholdcouldbereasonablydescribedasadis-tributionhavingameanmuchhigherthan7.5g/FA,theSTPLARappliedasharp,single-valuethresholdtomaintainclarityonthisreactorperformance metric.References

1.CHLE-012T1MBLOCATestReportRev4.Albuquerque,NM:UniversityofNewMexico,February18,2014.(ML14072A084)2.CHLE-014T2LBLOCATestReportRev3.Albuquerque,NM:UniversityofNewMexico,February22,2014.(ML14072A085)2.2.5.16SSIB,DebrisBypass:Question39a STPResponse:(Item39(a)iii,Page79)(i)The"berwaspreparedwithanARLmodi"edNEIprotocol(LAREnclo-sure4-3,Reference26,page16).Thegeneral"berpreparationprocedureTuesday1 stMarch,2016:19:32,Page219of393 DRAFTPART2.RAIRESPONSES(ROUND1)was(LAREnclosure4-3,Reference26,AttachmentA):(1)Ensuredrainvalveindebrispreparationtankisclosed.(2)Ensurethedebris"lterisinstalledonthereturnlinefromthetank.

(3)Weighoutthepredeterminedbatchsizeof"berandplaceintothescaledupdebrispreparationtank.(4)RecordquantityanddebrislotinformationinTable4.

(5)Filldebrispreparationtankwithwatertoatleasttheminimumdilu-tionspeci"edintheNEIdebrispreparationprotocol(0.72lbm/gal).

For2.4lbmof"ber,therecommendeddilutionbasedontheshake-downtestingresultsin30gal.(6)Startrecirculating"owpumpforthedebrispreparationtank.

(7)Ensurethepressurewashernozzlesareconnected.

(8)Changetheheightofthepressurewashernozzlestobewithin2inaboveorbelowthewatersurface.(9)Startthepressurewasherandrunapproximately15min(determinedfromshakedowntestingfor2.4lbmof"ber).(10)Examinedebrischaracteristicsforthebatchandnotethecom-mentssectiononthefollowingpage.Ifdebrischaracteristicsdo notmeetexpectations,applyhighpressuresprayforanextended durationasneeded,anddocumentincommentssection.(11)StopthepressurewasherandrecordtheactualtimeoverwhichthespraywasappliedinTable4.(12)Placeacleanbarrelunderthedebrispreparationtankanddraindebristhroughthevalveinthebottomofthetank.(13)Rinsetankwallsandensure"lterisfreeofdebris.

(14)Labelthebarrelcontainingthedebriswiththebatchnumberandde-brisweight.Anydeviationsfromthisprocedureweredocumentedfor eachtestinAttachmentAoftheSouthTexasPenetrationTestRe-port(LAREnclosure4-3,Reference26).Forexample,Tests1through 4interchangedsteps10and11whichwerenotedwithinkandini-tialmodi"cationsduringtesting.(ii)Analysistoquantitativelycharacterizethe"berafterpreparationandpriortotestingwasnotconducted.However,step10ofthe"berpreparation procedure,asdescribedaboveallowsthe"bertobehighpressuresprayed multipletimesiftheexpectationofthemostlyclass2"berswasnotmet.(iii)Step15of"berpenetrationtestprocedurerequiresgentlyre-mixingthedebrisusingamixingpaddlebeforethedebrisisintroducedinto thehopper/test"ume(LAREnclosure4-3,Reference26,AttachmentA).

Thedebrishopperalsointroducesadditionalmixingenergytothedebris beforeitentersthe"ume.Tuesday1 stMarch,2016:19:32,Page220of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.17SSIB,DebrisBypass:Question39bSTPResponse:(Item39b,Page79)Thesubsequentbatchof"berwasnotaddedtothetestuntilatleast5poolturnoverswerecompleted(LAREnclosure4-3,Reference26,page26).Sincethe testswereconductedatt"owrates,thedurationofapoolturnoveralso varied.Thedurationsof5poolturnoversforTests15,Test6,andTest7were11.8minutes,50.5minutes,and19.1minutes,respectively(LAREnclosure 4-3,Reference26,AttachmentA).2.2.5.18SSIB,DebrisBypass:Question39c STPResponse:(Item39c,Page79)Aschematicofthetestcon"gurationisbelow(LAREnclosure4-3,Reference26,page21).AtableofthedimensionscriticaltoqualityforTest1isshownonthesubsequent page(LAREnclosure4-3,Reference26,AttachmentA).Tuesday1 stMarch,2016:19:32,Page221of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.19SSIB,DebrisBypass:Question39dSTPResponse:(Item39d,Page80)Turbulencewasintroducedintothetesttankviamixers.Themixersprovidedenoughturbulencetosuspenddebrisinthetesttankandpreventdebrisfrom settlingtothe"oor(LAREnclosure4-3,Reference26,page16).Sincethe"ber remainedsuspended,alldebrisreachedthestrainer.2.2.5.20SSIB,DebrisBypass:Question39e STPResponse:(Item39e,Page80)ThetestsetupasdescribedinresponseSSIBRAI39censuresfull"owthroughthe"lterbagsduringthetest.Additionally,theNUKON Rwaspre-paredas"neshavingacharacteristicdiameterof7microns(LAREnclosure 4-3,Reference44,Table3-2).Thenominalporesofthebagsusedfor"ber collectionwas(were)5microns.Thelargerdiameter"nes,combinedwiththe randomorientationofthe"berasitcontactedthe"lterbag,suggeststhatdebris didnotbypassthe"lters.2.2.5.21SSIB,DebrisBypass:Question39f STPResponse:(Item39f,Page80)Yes,thepenetrationtestwasprototypicalwithrespecttotheSTPstrainer.Tuesday1 stMarch,2016:19:32,Page222of393 DRAFTPART2.RAIRESPONSES(ROUND1)ASTPprototypicalPCISure-Flostrainermodulewastested.The"owratewasscaledsuchthatthemaximumapproachvelocitiesofthetestsandtheSTP strainerwereequivalentat0.0086ft/s(LAREnclosure4-3,Reference26,Table 3,page19).Tests1through4weretestedwithatotalof2.4lbof"ne"brous debris;Tests5through7weretestedwithatotalof9.6lbof"ne"brousdebris (LAREnclosure4-3,Reference26,Table3,page19).TheDesignBasisAccident (DBA)testatARLinJulywasconductedwithatotalof5.5lbof"ne"brous debris(1).

Reference:

1.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportforECCSStrainerTestingJuly2008.RevisionA.11/24/2008.2.2.5.22SSIB,DefenseinDepthandMitigativeMeasures:Question 41aSTPResponse:(Item41a,Page81)Areductionin"owwilloccur(one(1)ContainmentSpraySystem(CSS)pumpsecured)beforeswitchovertorecirculationasdirectedbytheconditional informationpage(CIP)inSTPprocedure0POP05-EO-EO00,ReactorTrip orSafetyInjection(LAREnclosure4-3,Reference32).SecuringasingleCSS pumpwillconserveRefuelingWaterStorageTank(RWST)inventory.PerEOP 0POP05-EO-EO10,LossofReactororSecondaryCoolantallsprayscanbe securedafter6.5hoursbasedonIodinelevelslowenoughtosupporthabitability butcontainmentpressurewouldneedtobelessthan6.5psigandTSCconcur-rence.ConservationofRWSTvolumeandreductionofstrainer"owareboth bene"cialstrategiesforLOCAresponsethatcanbeachievedbysecuringspray

pumps.ThethirdCSSpumpisstoppedshortlyaftertheLOCAoccurs,beforetheRWSTisempty.Asaconsequence,whenrecirculationstarts,thattrainwill haveapproximately40%less"owthroughthestrainerresultinginmuchless debrisaccumulationandthereforeheadlosses(onthattrainsstrainer).StoppingaCSSpumpinthemostlikelyplantstatescenario(allCSStrainsrunning)isintendedtoconserveRWSTinventory.Additionally,the"owthrough theEmergencyCoreCoolingSystem(ECCS)strainerwillbereducedbyapprox-imately40%inthetrainthattheCSSpumpisstopped.Thisreductionintotal "owthroughthestrainerhastheadditionalbene"tofreducingdebrisbuildup onthatspeci"cstrainer.Apotentiallyadverseofsecuringspray"owis thatthelowerdebrisbedinventoryallowsmore"berpenetrationtothecore.Intherisk-informedmethodology,theofthereductionin"owistakenintoaccountasdescribedintheLAREnclosure4-2,SectionA.4.2,page83of257inthedescriptionofTopEventOFFS.Thestrainerloadingisaccountedfor asfoundinLAREnclosure4-3,Equations87through93page210of248and Section3page78of248(6e:Itwasassumedthatthedebristransporttoeachofthestrainersisproportionaltothe"owratethrougheachstrainerdividedby thetotal"owratethroughallofthestrainers.Thisisareasonableassumption sincethedebristransportswiththe"ow.

)Tuesday1 stMarch,2016:19:32,Page223of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.23SSIB,DefenseinDepthandMitigativeMeasures:Question 41bSTPResponse:(Item41b,Page81)STPNOCdidnotrevisetheEmergencyOperatingProcedure(EOP)Emer-gencyCoreCoolingSystem(ECCS)terminationcriteriatosecureanytrainsof safetyinjection.TheEOPsweremodi"edtosecureonetrainofContainment SpraySystem(CSS)ifallthreetrainsareinjecting.2.2.5.24SSIB,DefenseinDepthandMitigativeMeasures:Question 41cSTPResponse:(Item41c,Page81)No.STPNOCdoesnothaveaprocedureorguidancetoallowbackwashingoftheECCSstrainers.2.2.5.25SSIB,DefenseinDepthandMitigativeMeasures:Question 41dSTPResponse:(Item41d,Page81)AsstatedintheLAREnclosure4-1,pageC14theSTPEmergencyOp-eratingProcedures(EOPs)containstepstore"lltheRefuelingWaterStorage Tank(RWST).STPprocedure0POP05-EO-EO10"LossofReactororSecondary Coolant"directstheoperatortoenterprocedure0POP05-EO-ES13Transfer toColdLegRecirculation.0POP05-EO-ES13directstheoperatorstore"llthe RWSTinthestepfollowingcompletionoftransfertocoldlegrecirculation.

FollowingahypothesizedlargebreakLOCA,thiswouldoccurabout20to25 minutesfollowingthestartoftheevent.Themakeup"owratetoRWSTisapproximately150gpm.Thisequatestoapproximately11hourstomakeup100,000gallons.Theminimumvolume allowedintheRWSTbeforesecuringtheECCS/CSSpumpsis32,500gallons bytheprocedure.IntheunlikelyeventthatdebrispreventsrecirculationinallEmergencyCoreCoolingSystem(ECCS)trainsin11hours,theRWSTwouldbetlyfull ofwater.There"llrate(plusRWSTdraindown)wouldbeabletomeetcore coolingrequirementswithoutinterruptionoveralongperiodoftimeasshownin theLAREnclosure4-3,Table5.10.1page224of248.Thustheactionstore-"ll intheRWSTwillbeeforprovidinganalternativemethodofcooling watersupply.2.3ML14202A045,Thirdsetofresponses2.3.1APLABResponses2.3.1.1APLAB,CASAGrande-General:Question1a STPResponse:(Item1a,Page34)ThefollowingInputparameterSummaryTableprovides:a.Thebasisforusingapointestimateoradistribution.b.Thesourceoftheparametervalue(e.g.,licensingbasiscalculation).c.WhethertheparameterisbasedonanNRC-acceptedvalue(denotedby asterisk)Tuesday1 stMarch,2016:19:32,Page224of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThefollowingcategorizationsdfromVolume6.2,Table2.5.65.Thedis-crepancieshavebeenenteredintheSTPcorrectiveactionprogramtobead-dressedinanyfuturesubmittalofthisinformation.InputParameterVolume6.2,Table2.5.65RAIResponseTableTimetosecurecontainmentSprayFixedValueDistribution BlowdowntransportDistributionFixedValue WashdowntransportDistributionFixedValue FiberglasspoolerosionDistributionFixedValue Conventionalheadlossbump-upFixedValueDistribution Unquali"edCoatings(epoxy)NotincludedDistribution InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Timeto Recircu-lationFixedvaluesBreaksizeSwitchoverfromtheRWSTtoRecircula-tionisanautomaticfunction.Timetorecirculationasa functionofbreak sizeisbasedupon systemresistance (systemsline-ups),

RWSTvolumeandpumpperformance.Thesevaluesare"nite and"xed.Therefore, TimetoRecircula-tionisconsidereda "xedvalue(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013Timeto securecontain-ment SprayDistributionNoneOperatoractionstosecureonecontain-mentspraypumpand operatoractionsto securethecontain-mentspraysystem aredictatedbySTP OperatingProcedures 0POP05-EO-EO10,and0POP05-EO-ES11respectively.

Sincethistimeisde-pendentonoperator action,awindowof performancetimeisde"nedforeachac-tion.(32)0POP05-EO-EO10.LossofReactororSecondaryCoolant.(34)0POP05-EO-ES11.SITer-

mination.

(35)EmailfromTimSande (Alion)toKerryHowe(UNM) andErnieKee(STP).Best-EstimateTimeforSprayOper-ation:February23,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page225of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Timeto hotlegswitchoverDistributionNoneTimetothestartofhotlegswitchover is5.5hoursaftertheeventinitiationanddeterminedby monitoringplant conditionsviaSTP OperationProcedures

0POP05-EO-EO10.LossofReactororSecondaryCoolant and0POP05-EO-ES14.TransfertoHot LegRecirculation.

Plantconditionswill varybaseduponbreaksizeandoper-atingsafetysystems.

Timetothestartof hotlegswitchover is5.5hours.Itwas assumed(LAREncl.

4-3,Assumption1.j.),fromcommunicationwithplantpersonnel, thatthisactioncanbe completedwithin15 minutes.Itwassam-pledasadistribution ofequallylikelytimesbetween5.75and6hourstoaccountfor variationinoperator actiontimes.Since thetimetohotleg switchovermayvary slightlyandisbaseduponvariableplantconditionsitismod-eledasaprobability

distribution.(32)0POP05-EO-EO10.LossofReactororSecondary Coolant.

(36)0POP05-EO-ES14.Trans-fertoHotLegRecirculation.Containment Geome-tryFixedvaluesNoneThecontainmentphysicalcondition is"xedbaseduponas-builtconditionsasisthereforea"xed valueinput.(4)ALION-SUM-WEST-2916-01.CADModelSummary:

SouthTexasReactorBuildingCADModelforUseinGSI-191Analyses.Revision3:Novem-ber27,2012.

Break size andfre-quencyDistributionsBreakLocationAprobabilitydis-tributionisusedto modeltheLOCA frequencyforbreaksoftsizesattlocations withintheplant.

Breaksizeandfre-quencyareinherently variableandaprob-abilitydistributionmodelsthisvariabil-ity.

Statisticalsampling strategiesensure thattheDEGBcon-ditionsforevery pipe,discreteendpointsoffrequencydistributions,are explicitlyincludedin theevaluation.(4)ALION-SUM-WEST-2916-01.CADModelSummary:

SouthTexasReactorBuilding CADModelforUseinGSI-191 Analyses.Revision3:Novem-ber27,2012.(7)KNFConsultingServices LLC,andScandpowerRisk ManagementInc.Development ofLOCAInitiatingEvent FrequenciesforSouthTexas ProjectGSI-191FinalRe-portfor2011WorkScope.September2011.

(8)UniversityofTexasat Austin.ModelingandSam-plingLOCAFrequencyand BreakSizeforSTPGS1-191 Resolution.January23,2013.(9)Scandpower.RiskInformedGSI-191ResolutionLOCAFre-quencyComponentDatabase.

Revision2:October21,2011.

(37)NUREG-1829.Estimat-ingLoss-of-CoolantAccident (LOCA)FrequenciesThroughtheElicitationProcess:April 2008.continuednextpage...Tuesday1 stMarch,2016:19:32,Page226of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Poolvol-umeDistributionsBreakSizeTherearethreesourcesofwaterfor alossofcoolantaccident(LOCA):therefuelingwater storagetank(RWST),

thereactorcoolant system(RCS)and thesafetyinjection(SI)accumulators.Eachofthesources aremaintainedwithin speci"cvolume/mass

ranges.

Sincethereisarange ofvalues,theuseofadistributionratherthanapointvaluewas chosen.(14)ALION-CAL-STP-8511-01.STPPostLOCAWater VolumeAnalysis.Revision1:September20,2012.Pool areaFixedvalueNoneThisisaphysicalcon-ditionoftheplantand notvariable.There-forea"xedvalueis appropriate.(14)ALION-CAL-STP-8511-01.STPPostLOCAWater VolumeAnalysis.Revision1:

September20,2012.PoolTemper-atureFixedValuesBreakSizePooltemperaturewasselectedtobea"xed value.Onerepresen-tativetemperature historywaschosen torepresentsmallandmediumbreaks,andonerepresen-tativetemperature historywaschosen torepresentlarge breaksfromasuite ofthermalhydrauliccalculationsbasedonnominalconditions.

Alternativetemper-aturesunderfailure conditionswould havesuccessively lowerprobabilityofoccurrence.Nominalpro"leswere chosenbecauseitis notclearwhetherthe minimumormax-imumtemperature pro"lesareconserva-tiveduetocompetingfactors.Itwasalso assumedthatnominal temperaturepro"les aregenerallymore conservativedueto theshapeoftheirtransientbehavior(LAREncl.4-3, Assumption1.k.).(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:

January2013.*Containment pressureFixedvaluesPoolTemperatureFixedvalueswerecho-senbaseduponthe ASMESteamTables orassuminga"xedvalueof14.7psia.Saturationpressure attemperatureisa constant.Thisiscon-sistentwithaccident phenomenologyand USNRCguidelines.GeneralAssumptions1.c-Containmentpressurewasas-sumedtobe14.7psiaforall casesexceptwhenthepooltemperatureishigherthantheboilingtemperature.Incases wherethepooltemperatureis above212ûF,thecontainment pressurewasassumedtobe equaltothesaturationpres-sure.Thisisaconservativeas-sumptionsinceneglectingcon-tainmentoverpressurereduces theECCSpumpNPSHmargin andincreasestheamountofde-gasi"cationatthestrainer.Operating pumpsFixedvaluesNoneThenumberofoper-atingpumpsisconsid-ereda"xedvalueandaspeci"cdesigninput asapplicabletoeach plantfailurestate.(38)STP-2699325-O-03.Sub-ject:OntheFrequencyofSuc-cessStatesInvolvingtNumbersofPumpsOperating.

December18,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page227of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Low headsafety injection "owrateFixedvaluesBreakSize,PumpsRun-ningFlowrateisspeci"cvaluedeterminedby operatingpumps(seeabove)andaspeci"cdesigninputasap-plicabletoeachplant failurestate.These operatingline-upsare "xed.Therefore,sys-tem"owrateiscon-sidereda"xedvaluethatisdeterminedby thenumberofoperat-ingpumpsandbreak

size.(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013.

(41)MC-6220.SI&CSPump NPSH.Revision4:February5, 2002.High headsafety injection "owrateFixedvaluesBreakSize,Pumpsrun-ningFlowrateisspeci"cvaluedeterminedbyoperatingpumps(seeabove)andaspeci"c designinputasap-plicabletoeachplant failurestate..These operatingline-upsare "xed.Therefore,sys-tem"owrateiscon-sidereda"xedvalue thatisdeterminedby thenumberofoperat-ingpumpsandbreak

size.(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013.

(41)MC-6220.SI&CSPump NPSH.Revision4:February5, 2002.Containmentspray"owrateDistributionsPumpsRunningIfcontainmentspraysareinitiated,the"owrateisnotdepen-dentonthesizeof thebreak.Flowrate variesdependingon thenumberoftrains inoperation.Thenumberoftrainsinoperationisdis-tributedoverthe rangeofbreaksizes andoperatingtrains.

Basedonthedis-tributedbreaksizesthecontainmentspray"owrateisinputasa

distribution.(41)MC-6220.SI&CSPumpNPSH.Revision4:February5, 2002.(42)5N109MB01024.Design BasisDocumentContainment Spray.Revision3:November 17,2004.*Quali"ed coatings quantityFixedvaluesNoneThequali"edcoatingquantitiesarebased onacombinationof plantcon"gurationandNRCapprovedanalysismethods.

Quali"edcoatings quantitiesarecon-sidered"xedvalues astheyarebasedon speci"cconservativebreakscenarios.(11)ALION-CAL-STP-8511-03.STPQuali"edCoatings DebrisGeneration.Revision0:

August10,2012.

• Unquali"ed coatings quantity (non epoxy)FixedvaluesNoneTheunquali"edcoatingquantities (non-epoxy)arebased onacombinationof plantcon"gurationandNRCapprovedanalysismethods.

Unquali"edcoatings quantitiesareconsid-ered"xedvaluesas theyarebasedoncon-servativeassumptionsregardingunquali"edcoatingdegradation.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:

November26,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page228of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)*Unquali"ed

coatingsquantity(epoxy)DistributionNoneTheunquali"edcoat-ingquantitiesare basedonacom-binationofplantcon"gurationand NRCapprovedanaly-sismethods.

Epoxyunquali"ed coatingsquantitiesareconsideredadistributionand arebasedonthe EPRIandCarboline

analysis.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:November26,2012.

• Unquali"ed coatings failure timeFixedvaluesNoneThetimeafterthestartoftheLOCAeventthattheunqual-i"edcoatingfailsis determinedbyanaly-sisofdatapresented intheEPRItestre-portDesignBasisAc-cidentTestingofPres-surizedWaterReac-torUnquali"edOrigi-nalEquipmentManu-facturerCoatings.Fi-nalReportSeptember

2005.

Timingisinputasa"xedvalueasitisagivenspeci"cdesign

parameter.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:November26,2012.

CrudquantityFixedvalueNoneThisisaphysical"xedvaluebasedon industryboundinges-timatesoftheamountofcrudavailablewithintheReac-torCoolantSystem andsteamgenerator tubes.Thisamount doesnotvarywith breakselectionandisthereforeinputasa"xedvalue.Acknowl-edgedvariationsin thisparticulatesource donotcompetewith dominantsources likefailedunquali"ed coatings.(13)ALION-CAL-STP-8511-07.STPCrudDebrisGenera-tion.Revision0:November12, 2012.*Latent debris quantityFixedvaluesNoneThelatentdebrisquantitiesarebased onacombination ofplantcon"gura-tion,conservative assumptionsandNRCapprovedanalysismethods.

Latentdebrisquan-titiesareconsidered "xedvaluesasthey arebasedonassumed plantconditions.(43)ALION-CAL-STPEGS-2916-002.GSI191Contain-mentRecirculationSump Evaluation:DebrisGeneration.

Revision3:October20,2008.

• Miscellaneous debris quantityFixedvalueNoneMiscellaneousdebrisquantitiesarebased onacombination ofplantcon"gura-tion,conservative assumptionsandNRCapprovedanalysismethods.

Miscellaneousdebris quantitiesarecon-sidered"xedvalues astheyarebased onassumedplant conditions.(43)ALION-CAL-STPEGS-2916-002,GSI191Contain-mentRecirculationSump Evaluation,DebrisGeneration.

Revision3:October20,2008.continuednextpage...Tuesday1 stMarch,2016:19:32,Page229of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Miscellaneous

debris failure timeFixedvalueNoneMiscellaneousdebriswasassumedtofail atthebeginningoftheevent.Itisthereforeconsidered a"xedvalueinput.

Miscellaneousdebris failuretimeincludes bothcrudandlatent debris.DebrisGenerationAssump-tions,4.b-Itwasassumed that100%ofthemiscellaneousdebris(tags,labels,etc.)wouldfailatthebeginningofthe event.Thisisaconservative assumptionsincethemajority ofthemiscellaneousdebris wouldbeoutsidetheZOIand maynotfailatallduringtheevent.*Insulation ZOIsizeFixedvaluesBreakSize,InsulationLo-cationInsulation-speci"cZOIsizeshavecom-monlyaccepted conservativedef-initionsthatare consistentwiththoseusedforstrainerdesign.Plausible reductionsinZOI sizehavenotbeen de"nitivelydemon-stratedbytesting,sodeterministicZOIsizeswereadoptedas "xedvalueinputs.(44)NEI04-07Volume1.PressurizedWaterReactor SumpPerformanceEvaluation Methodology.Revision0:

December2004.

(45)NEI04-07Volume2.SafetyEvaluationbytheOf-"ceofNuclearReactorRegu-lationRelatedtoNRCGeneric Letter2004-02,NuclearEn-ergyInstituteGuidanceRe-port"PressurizedWaterReac-torSumpPerformanceEvalua-tionMethodology".Revision0:December2004.*Fiberglasssizedis-tribu-tionFixedvaluesBreakSize,InsulationLo-cationThe"berglasssizedistributionisaspe-ci"cdesigninputto theanalysis.TheZOIsizesdonotchargeandthereforesize distributionsarealso considered"xedvalue

inputs.(46)ALION-REP-ALION-2806-01.InsulationDebris SizeDistributionforUsein GSI-191Resolution.Revision4:May20,2009.

Debrischarac-teristicsFixedvaluesNoneThephysicalchar-acteristicsofdebris,i.e.density,materialcomposition,etc.are derivedfrommanufac-turersdata.Asthe physicalcharacteris-ticsdonotvarywith accidentscenario,theyareconsidered"xedvalues.(11)ALION-CAL-STP-8511-03.STPQuali"edCoatings DebrisGeneration.Revision0:August10,2012.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:

November26,2012.

(13)ALION-CAL-STP-8511-07.STPCrudDebrisGenera-tion.Revision0:November12, 2012.

(43)ALION-CAL-STPEGS-2916-002.GSI191Contain-mentRecirculationSump Evaluation:DebrisGeneration.Revision3:October20,2008.

• Chemical product forma-tion timeFixedvaluesNoneChemicalproductformationtimeisset toa"xedvalue,zero (0.0),sothatoppor-tunityforchemical productformationexistsatalltimesduringallscenarios.

TheparameterChem-icalPrecipitation Temperaturecontrols theactualtimewhen chemicalinducedhead-lossareintroduced.(20)CHLE-016.CalculatedMaterialRelease.Revision1:

January10,2013.*Blowdown trans-portFixedValuesBreakLocation,Debris SizeWhileblowdowntransportisafunction oftheeventandvaries witheachevent,asdescribedinALION-CAL-STP-8511-08, conservative"xed valueswereadopted toaidunderstanding ofcomplextransport logicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.continuednextpage...Tuesday1 stMarch,2016:19:32,Page230of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)*Washdown trans-portFixedValuesSpraysinitiated,Debris SizeWhilewashdowntransportisafunction oftheeventandvarieswitheachevent,asdescribedinALION-

CAL-STP-8511-08, conservative"xed valueswereadopted toaidunderstanding ofcomplextransportlogicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.*Pool"ll trans-portFixedvaluesBreakLocation,Debris SizeTheanalysisassumesthatalllatentdebris andZOIdebrisintro-ducedat"oorlevelis subjecttotransporttoinactivecavitiesandtothestrainers duringpool"ll.Al-thoughuncertainties existintheaccepted methodology,"xed valueswereadoptedtoaidunderstandingofcomplextransport logicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.

• Recirculation trans-portFixedvaluesBreakSize,BreakLoca-tion,DebrisType,Debris

SizeThevarioustypesandsizesofdebris transporttly duringtheblowdown,washdown,andpool"ll-upphases.The spatialdistribution ofthisdebrisatthe startofrecirculation couldvarywidely becauseinsulationde-brisonthepool"oorwouldbescattered aroundbythebreak "owasthepool"lls, anddebrisinupper containmentwould bewasheddownatvariouslocationsbythespray"ow.To approximatethis complexity,conserva-tivefractionsof"ne andsmalldebris(and allparticulates)areassumedtobehomo-geneouslymixedand availablefortransport byECCSrecircula-tion"owde"nedby thenumberofpumps operating.Therefore,recircu-lationtransportis consideredas"xed values.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.*Fiberglassspray erosionFixedvalueSpraysinitiatedFiberglasssprayero-sionisbasedupon testdata.Spray"owrateisapproximatelyconstant.Therefore Fiberglasssprayero-sionisconsidereda "xedvalue.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.*Fiberglasspoolero-sionFixedvalueNoneFiberglasssprayero-sionisbasedupontestdata.Pool"owveloc-itiesvarybasedupon thephysicalcon"gu-rationoftheSTPcon-tainment.Toapproxi-matethiscomplexity, asingleconservativevalueofsprayerosionisassumed(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.(new)ALION-REP-ALION-1006-04.ErosionTestingof SmallPiecesofLowDensity FiberglassDebrisTestRe-port.Revision1:November7, 2011.continuednextpage...Tuesday1 stMarch,2016:19:32,Page231of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Fiberglass poolero-sion timeFixedvaluesNoneFiberglasspoolerosionisasmall additionalfractionofthetotal"ne"beravailablefortrans-port,sothetotal expectedquantity oferoded"berwas introducedtothepoolpriortorecirculationasa"xedvalue.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.(new)ALION-REP-ALION-1006-04.ErosionTestingof SmallPiecesofLowDensity FiberglassDebrisTestRe-port.Revision1:November7, 2011.Transport timeFixedvaluesSumpFlowRate,PoolVol-ume,FailureTimeTransporttimeisbaseduponevent timingandpump"ow rateswhichhaveas-signeddistributions.

Becausetransporttimeiscalculatedprescriptively,itis describedhereas a"xedvalue,even thoughtransporttime dependsonrandom factors.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.

Strainer geome-tryFixedvaluesNoneStrainergeometryisbasedupontheplant physicalconditionand isadirectnumerical input.Itwastherefore inputas"xedvalues.(47)SFS-STP-PA-7101.SouthTexasProjectUnits1&2Sure-FlowStrainerModuleDetails.

Revision5:September5,2006.

(48)TDI-6005-01.SFSSurface Area,FlowandVolumeCalcu-lations.Revision1:August31, 2006.

(49)SFS-STP-GA-00.South TexasProjectUnits1&2 Sure-FlowStrainerGeneral Arrangement.Revision4:

September7,2006.(50)SFS-STP-PA-7103.SouthTexasProjectUnits1&2Sure-FlowStrainerSectionsandDe-tails.Revision2:August4, 2006.

(51)2F369PS10572Sheets3,4

&6.SafetyInjectionSl(52)5L019PS0004.Speci"ca-tionforCriteriaforPipingDe-signandInstallation.Revision 23:s.n.Geometric strainer loadingFixedvaluesStrainergeometryGeometricstrainerloadingisbasedupon thestrainerphysicalgeometry.Itisadi-rectnumericalinput.

Itwasthereforeinput as"xedvalues.(47)SFS-STP-PA-7101.SouthTexasProjectUnits1&2Sure-FlowStrainerModuleDetails.Revision5:September5,2006.(48)TDI-6005-01.SFSSurface Area,FlowandVolumeCalcu-lations.Revision1:August31, 2006.

(49)SFS-STP-GA-00.South TexasProjectUnits1&2Sure-FlowStrainerGeneralArrangement.Revision4:

September7,2006.

Clean strainer head lossFixedvalueNoneCleanstrainerheadlossisahydraulic attributebasedupon thephysicaldimen-sionsofthestrainer.Itisthereforea"xed value.(53)66-9088089-000.SouthTexasProjectTestReport forECCSStrainerTesting.

Revision0:August29,2008.

Thin-bed thick-nessFixedvalueNoneThethin-bedthick-nessis1/16thof aninch.Thisisa physical"xedvalueassumption.Uncer-taintyregardingthe exactvalueofthis transitionthicknessis beingaddressedusing parameterstudies ratherthandirectpropagationofa distribution.DebrisGenerationAssump-tions,7.c-Itwasassumedthat a"berbedofatleast1/16thof aninchisnecessarytocapture chemicalprecipitates.Thisisareasonableassumptionsinceathinnerdebrisbedwouldnot fullycoverthestrainerand wouldnotsupportappreciable headlossesduetochemical

debris.continuednextpage...Tuesday1 stMarch,2016:19:32,Page232of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Conventional headloss bump-upDistributionNoneAccuracyofthe NUREG/CR-6224 correlationisknowntovarywithrespecttodebriscomposition.

Also,knowndefects intheconventional implementationof theequationraisequestionsregardinggeneralapplicability.

Toaccountforthe presenceofextreme conditionsinthesce-nariosamplespace, exponentialprobabil-itydistributionswerede"nedandapplied asdirectmultipliers totheestimatedcon-ventionalheadloss.

Becauseconsensus ontheseissuesistoestablish,theconventionalhead lossbump-upisinput asadistribution.Section5.6.2,ConventionalDe-brisHeadLossModel-The NUREG/CR-6224correlation wasselectedfortheCASAcomputationofconventionaldebrisheadlossacrossthe strainer.Thiscorrelationis asemi-theoreticalheadloss modelandisdescribedindetail inAppendixBofNUREG/CR-6224 Chemicalheadloss bump-upDistributionsBreakSizeThecorrosionanddissolutionrelease modelandthesol-ubilitymodelwerenotdirectlyimple-mentedinCASA Grande.Therefore,a setofchemical bump-upfactorprob-abilitydistributionsweredevelopedandappliedforallbreaks.

Toaccountforthe presenceofextreme conditionsinthesce-nariosamplespace, exponentialprobabil-itydistributionswerede"nedandapplied asdirectmultipliers totheestimated conventionalhead loss.Theprobability distributionswerede-velopedbasedonthecurrentresultsfrom theCHLEtestingand onchemicalhead-lossobserved duringSTPstrainer

testing.(20)CHLE-016.CalculatedMaterialRelease.Revision1:

January10,2013.

Pump NPSH requiredFixedvaluesVoidFractionThisisaphysicalcharacteristicofthe pump.Fixedvalues werede"nedbythe pumpvendorare thereforeinputas "xedvalues.(25)ALION-CAL-STP-8511-05.STPNetPositiveSuction HeadMargin.Revision0:

November19,2012.

Pump NPSH availableFixedvaluesPoolTemperature,PumpFlowRate,PoolLevel, ContainmentPressurePumpNPSHavailableisde"nedinALION-

CAL-STP-8511-05.

Theyaretherefore inputas"xedvalues.(25)ALION-CAL-STP-8511-05.STPNetPositiveSuction HeadMargin.Revision0:

November19,2012.

Strainer struc-tural marginFixedvalueNoneStrainerstructuralmarginvaluesareme-chanicalpropertiesof thestrainermaterial andcodeallowables.

Theyaretherefore inputas"xedvalues.

Also,seetheresponsetoEMCB-RAI-1pro-videdtotheNRC inSTPletter

NOC-AE-13003065, datedDecember23, 2013(ML14015A311).(54)EC-PCI-STP-6005-1001.AESDocumentNo.PCI-5473-SO1Rev2"StructuralEvaluationofStrainersfor ContainmentEmergency Sumps".Revision2:January 7,2010.

(55)EC-PCI-STP-6005-1004.

AESDocumentNo.PCI-5473-S03Rev0"StructuralEvaluationofStrainersfor ContainmentEmergency SumpsforLongTermPost LOCACase".Revision0:

January7,2010.continuednextpage...Tuesday1 stMarch,2016:19:32,Page233of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Containment relativehumid-ityFixedvalueNoneContainmentrelativehumiditywasassumed tobe100%.Thisisa"xedvalueanddoesnotchangethrough-outtheanalysis.DebrisGenerationAssump-tions,8.e-Itwasassumed thattherelativehumidityofthecontainmentatmosphereis 100*Pumpgasvoid limitsFixedvalueNonePumpgasvoidlimitsareasde"nedin USNRCRegulatory Guide1.82.WaterSourcesforLong-TermRecirculation CoolingFollowing aLoss-of-Coolant Accident.Thisisa "xedvalue.(59)RegulatoryGuide1.82.WaterSourcesforLong-Term RecirculationCoolingFollow-ingaLoss-of-CoolantAcci-dent.Revision4:March2012.Fiber"l-tration parame-tersDistributionsNoneFiber"ltrationofastrainerisafunctionofthemassofdebris onthestrainer.STP-speci"ctestingwas usedtoderivepa-rametersofthe"ltra-tionmodelandtheirassociateduncertain-ties.Therefore,the "ber"ltrationparam-etersareinputasa distributionbasedon testdata.(60)UniversityofTexasatAustin.FiltrationasaFunc-tionofDebrisMassontheStrainer:FittingaParametric Physics-BasedModel.s.l.June 5,2013.Fiber shedding parame-tersDistributionsNoneFibersheddingisafunctionofthe massofdebrisonthe strainer.STP-speci"c testingwasusedto deriveparametersof thesheddingmodelandtheirassoci-ateduncertainties.

Therefore,the"ber sheddingparame-tersareinputasa

distribution.(60)UniversityofTexasatAustin.FiltrationasaFunc-tionofDebrisMassonthe Strainer:FittingaParametric Physics-BasedModel.s.l.June 5,2013.Boil"owrateFixedvaluesNone"owratesareafunctionoftimeandofcorepowerandare basedonthephysi-calplant.Boil"ow ratewerethereforein-putas"xedvalues.(61)5N079NB01000(WCAP-12381).STPNOCDesignBa-sisDocumentAccidentAnaly-sis.Revision15:July29,2009.

(62)TechnicalSpeci"cations Section1.27.RatedThermal Power.Unit1AmendmentNo.

154;Unit2AmendmentNo.142:s.n.Number offuel assem-bliesFixedvalueNoneThenumberoffuelas-sembliesisaphysical plantparameterand doesnotvary.Itwas thereforeinputasa "xedvalue.(61)5N079NB01000(WCAP-12381).STPNOCDesignBa-sisDocumentAccidentAnaly-sis.Revision15:July29,2009.

• Coreblockage "ber limitsFixedvaluesBreakLocation,InjectionPathThermalhydrauliccalculationsofcore blockageprovided screeningcriteria thatrenderedthe coreblockagelimits obsoletefortheSTPanalysis.Coreblock-age"berlimitswere thereforeinputas "xedvaluesrepresent-ingextremelimitsof acceptableblockage.(63)WCAP-16793-NP.Evalu-ationofLong-TermCoolingConsideringParticulate,Fi-brousandChemicalDebrisin theRecirculatingFluid".Revi-sion2:October2011.continuednextpage...Tuesday1 stMarch,2016:19:32,Page234of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Boron precip-itation"ber limitsFixedvaluesBreakLocation,InjectionPathTheboronprecip-itation"berlimits areinherentlyuncer-tainbecauseofbothphysicalvariability andlackofknowledge regardingassociated phenomena.The boronprecipitation "berlimithasbeenidenti"edasakeyfactorcontrolling theriskofECCS failure.Itis toachieveconsensus regardingevenasinglevalueofthisimportantthreshold, letaloneastatistical distribution,boron precipitation"ber limitsweretherefore inputas"xedvaluesandtheimpacthasbeenemphasizedvia parameterstudies.(new)LetterfromSherBa-hadur(NRC)toAnthony Nowinowski(PWROG).Fi-nalSafetyEvaluationforPressurizedWaterReactorOwnersGroupTopicalReport WCAP-16793-NP,Revision 2,"EvaluationofLong-Term CoolingConsideringPartic-ulateFibrousandChemical DebrisintheRecirculatingFluid"(TACNo.ME1234):April8,2013.2.3.1.2APLAB,CASAGrande-General:Question1bSTPResponse:(Item1b,Page34)SeetheresponsetoAPLAB,CASAGrande-General:RAI1a.2.3.1.3APLAB,CASAGrande-General:Question1c STPResponse:(Item1c,Page34)SeetheresponsetoAPLAB,CASAGrande-General:RAI1a.2.3.1.4APLAB,CASAGrande-PlantCon"guration:Question1a STPResponse:(Item1a,Page35)Yes,varyingtheaforementioned(orother)parametersfromtheirnominalvalueswillproducetime-temperaturecurvesyieldinghigherconditionalproba-bilitiesofsumpandcoreblockageAsanexample,asummaryoftheStrainerMappingforRCFCsisshowninFigure1.2.3.1.5APLAB,CASAGrande-PlantCon"guration:Question1b STPResponse:(Item1b,Page35)Asstatedpreviously,pooltemperaturehasaneonmanyaspectsoftheoverallGSI-191evaluationincludingchemical(materialreleaseratesand solubilitylimits),debristransport,strainerheadloss,NPSHmargin,degasi"-

cation,andin-vesseleInsomecases,ahigherpooltemperaturepro"leis moreconservative(e.g.,NPSHmarginanddegasi"cation),inothercasesalower pooltemperaturepro"leismoreconservative(e.g.,strainerheadlossanddebris transport).Withrespecttopooltemperature,duetoitscompetingandcomplexityofontheoverallevaluation,itisnotpossibletopre-determinewhethera higherorlowerpooltemperaturepro"lewouldbemorelimitinginthedetermi-nationofCDForLERF.Thepremiseofarisk-informedevaluationistoconsideraholisticapproachwherecompetingecollide.Theuseofnominalpooltemperaturepro"lesisTuesday1 stMarch,2016:19:32,Page235of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:StrainerMapping.Frequenciesrepresenttheplantcon"gurationconditionedonLOCAFrequency.Frequencies

<1E-14(PRAtruncationfrequency)arereportedas zero.consistentwithaholisticrisk-informedapproachandprovidesamorerealisticevaluationofrisk.2.3.1.6APLAB,CASAGrande-PlantCon"guration:Question2a STPResponse:(Item2a,Page35)Yes,varyingtheaforementioned(orother)parametersfromtheirnominalvalueswillproduce"owratesyieldinghigherconditionalprobabilitiesofsump andcoreblockage.Asanexample,asummaryoftheStrainerMappingfor RCFCsisshowninFigure1.2.3.1.7APLAB,CASAGrande-PlantCon"guration:Question2b STPResponse:(Item2b,Page35)Thepremiseofarisk-informedevaluationistoconsideraholisticapproachwherecompletingorwidelyvaryingprovideoverlyconservativeandcom-petingresults.Theuseofnominal"owratesprovidesamorerealisticevaluation, isconsistentwithaholisticrisk-informedapproachandprovidesamorerealistic evaluationofrisk.Thegoalistoprovideareasonableprobability,notnecessarily amaximizationoftheprobabilityoffailure.Tuesday1 stMarch,2016:19:32,Page236of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:StrainerMapping.Frequenciesrepresenttheplantcon"gurationconditionedonLOCAFrequency.Frequencies

<1E-14(PRAtruncationfrequency)arereportedas zeroItisrecognizedandhasbeenstatedpreviously,that"owrateisoneofthemoreimportantinputparametersandhasanonmanyaspectsofthe overallGSI-191evaluation.Insomecases,ahigher"owincombinationwith otherfactorsproducesamoreconservativeresult.Inothercasesalower"ow incombinationwithotherfactorsproducesamoreconservativeresult.Using nominalvaluesprovidesresultsthatarereasonable,probableandthatmaybe usedinaholistic,risk-informedevaluation.2.3.1.8APLAB,CASAGrande-PlantCon"guration:Question3a STPResponse:(Item3a,Page35)Pumpstate22,thecasewhenonehighhead,onelowheadandonespraypumpisunavailable,waschosentoexploretheimpactoftheassumptionthat allfailedpumpsareonthesametrain.Pumpstate22waschosenfordetailed examinationasitisthemostlikelypumpstateinvolvingmultiplepumpfailures.Pumpstate22assumesthatallthreeunavailablepumpsareonthesametrain.Toexploretheimpactofunavailablepumpsbeingondttrains,four additionalcaseswereevaluated.Theresultsofthisanalysisindicatedthatthecon"gurationwhereallunavail-ablepumpsareonthesametrainleadstothehighestlikelihoodoffailureatthe sump.Threeoftheadditionalcasesinvestigatedthatinvolvedthreeunavailable pumpsbutonttrainsdidresultinconditionalfailurelikelihoodshigher thanpumpstate22.Intwoofthosecases,ahighercoredamagefrequency duetoin-vesselphenomenawaspredicted.ThelargerincreaseincoredamageTuesday1 stMarch,2016:19:32,Page237of393 DRAFTPART2.RAIRESPONSES(ROUND1)frequencyresultingfromthesetwocaseswasapproximately1.5%Detailsdocumentingtherationaleforselectingpumpstate22todemonstratetheimpactoftheassumption,theanalysisapproachandresultsarefoundin Enclosure1.2.3.1.9APLAB,CASAGrande-PlantCon"guration:Question3b STPResponse:(Item3b,Page36)2.3.1.10APLAB,CASAGrande-PlantCon"guration:Question3cSTPResponse:(Item3c,Page36)2.3.1.11APLAB,CASAGrandetoPRAInterface-General:Ques-tion2aSTPResponse:(Item2a,Page38)ThelargestbreaksizebelowwhichnofailuresrelatedtoeitherthesumporvesselperformancewererecordedduringtheCASAGranderunswasaDEGB ina5.189Dinchpipe.TheesizeoftheDEGBbreakina5.189Dinchpipeis5

.189x2 1/2=7.338inch.TheesizewasusedtoassignDEGBcasestoaLOCAcategory.Therefore,thisisthetransitionbreaksizebelowwhichnofailureswererecorded andabovewhichfailureswereobservedinsomecases.Thisspeci"cbreakwas characterizedasaLargeLOCA.2.3.1.12APLAB,CASAGrandetoPRAInterface-General:Ques-tion2bSTPResponse:(Item2b,Page38)TherearenoscenariotimingdforthedebrismodelcomparedtothebasePRA,changesinsuccesscriteriaasaresultofdebris,andchangesin operatorresponse.Figure1.3,fromLAREnc.4-3,reproducedbelow,showstherelationshipbetweentheSTPPRAmodelandCASAGrande.Withrespecttotimingand successcriteriathetwomodelsare,ofnecessity,consistent.Tuesday1 stMarch,2016:19:32,Page238of393 DRAFTPART2.RAIRESPONSES(ROUND1)Tuesday1 stMarch,2016:19:32,Page239of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.13APLAB,STPPRAModel-General:Question1STPResponse:(Item1,Page40)AnindependentfocusedpeerreviewfollowedanupgradetotheHumanReliabilityAnalysis.TheresultsofthatreviewarefoundinEnclosureA.No Signi"canceLevelA"ndingswerefound.AllLevelBobservations(Enclosure B)wereresolvedandincorporatedintothePRA.AfocusedindependentreviewoftheelectricpowerrecoveryanalysiswasperformedwiththeresolutionofthecommentssummarizedinEnclosureC.All commentshavebeenresolved.2.3.1.14APLAB,STPPRAModel-General:Question3 STPResponse:(Item3,Page40)Itwasdeterminedthattherequirementsspeci"edforinternaleventsat-powerPRAareapplicableforthisspeci"capplicationatSTP(pleasereferto theresponsetoAPLAB,STPPRAModel-RAI-2,NOC-AE-14003101,June25, 2014,ML14178A481andML14178A485).ThePRAonwhichtheGSI-191RIapplicationisbasedwasdevelopedfromtheSTPPRAmodelofrecord(MOR).TheSTPPRAMORhasbeenpeer reviewedandfoundtocomplywithcapabilitycategoryIIforallinternalevent, level1and2requirements.TheGSI-191PRArequiredfocusedmodi"cationofsixoftheeightinter-naleventtechnicalelements:InitiatingEventAnalysis(IE),AccidentSequence Analysis(AS),SuccessCriteria(SC),SystemsAnalysis(SY),andQuanti"cation (QU).TheHumanReliabilityAnalysis(HR),DataAnalysis(DA),andLERF Analysis(LE)werenotimpactedbythechangestotheMORtocreatetheGSI 191PRA.Theprocessofprovidingareasonablycompleteidenti"cationofrelevantinitiatingevents(HighLevelRequirementIE-A)isdiscussedintheenclosureto theresponsetoAPLAB,STPPRAModel-RAI-2,NOC-AE-14003101,June25, 2014,ML14178A481andML14178A485).Modi"cationstotheMORdidnotimpactthisHighLevelRequirementsothattheGSI191PRAmeetsallsupportingrequirementsderivingfromIE-A.

Likewisethegroupingoftheinitiators(thefocusofHighLevelRequirement IE-B)wasnotchangedfromtheMORsothattheGSI-191PRAmeetsall supportingrequirementsderivingfromIE-B.AsexplainedintheLAR,theGSI-191PRAdidadaptanapproachtothequanti"cationoftheLOCAfrequencies(thefocusofHighLevelRequirement IE-C)thatisdistinctfromthatadoptedintheMOR.Supportingrequirements IE-ClthroughIE-C6,IE-C12,IE-C13andIE-C15areapplicable.Timetrend analysis(IE-C7)isnotnecessarytomeetCapabilityCategoryII.Faulttree analysiswasnotused,soIE-C8throughIE-C11arenotapplicable.Supporting RequirementsIE-D1throughIE-D3(pertainingtoDocumentation)areapplica-

ble.Modi"cationstotheAccidentSequencemodelweremadetoexplicitlyin-cludetheimpactofGSI-191issues.SupportingrequirementsAS-Althrough AS-All,AS-B1throughAS-B7,andAS-ClthroughAS-C3areapplicable.HighLevelRequirementSC-Aspeci"estherequirementsforsuccesscriteria.Tuesday1 stMarch,2016:19:32,Page240of393 DRAFTPART2.RAIRESPONSES(ROUND1)SupportingrequirementSC-A2isapplicableasitprovidesguidanceforaccep-tancerequirements.SXC-A5(pertainingtomissiontime)andSC-A6(consis-tencywithfeatures,proceduresandoperatingphilosophy)areapplicable.The de"nitionofcoredamage(SC-Al),thesuccesscriteriaforkeysafetyfunctions (SC-A2)arenotmodi"edfromtheMORandthereforeremainCapabilityCate-goryIIandnotapplicableinthereviewoftheGSI191PRA.TheMediumand LargeLOCAaccidentsequencemodelsdonotcreditsystemssharedbetween thetwounits,soSC-A4isnotapplicable.SC-B1throughSC-B5(whichpertaintothermal-hydraulicandothersup-portinganalyses)areapplicable.SC-ClthroughSC-C3(pertainingtodocumen-tation)areapplicable.ThechangestotheSystemsModelsprimarilyinvolvedprovidinglogictoincorporatetheresultsofthesupportingphenomenologicalanalyses(e.g.,results fromCASAGrande).ApplicableSupportingRequirementsassociatedwithHigh LevelRequirementSY-A(whichseeksareasonablycompletetreatmentofcauses forunavailability)arelimitedtoSY-AlthroughSY-A7,SY-A9throughSY-A14,andSY-A21throughSY-A24.SY-A8referstoestablishingcomponent boundariesandisnotapplicable.SY-Al5throughSY-A20areotherwisenot applicable.SY-A15pertainstotruncatingthesystemmodel,whichwasnot doneinthesystemmodel.SY-A16andSY-A17pertaintohumanfactorswhich arenotincludedinthephenomenologicalmodels.SY-A18throughSY-A20are otherwisenotrelevant.HighLevelRequirementSY-Bfocusesonthereasonablycompletetreatmentofcommoncausefailures,intersystemandintersystemdependencies.Because thesystemsanalysesarebeingusedtointroduceeventsofaphenomenological nature,onlySY-B6whichaddressespotentialspatialorenvironmentalimpacts isapplicable.SupportingrequirementsSY-ClthroughSY-C3pertaintodocu-mentationandareapplicable.MostsupportingrequirementsassociatedwiththeQUHighLevelRequire-mentsareapplicable.TheoneexceptionisQU-D4which,forcapabilitycategory II,callsforthecomparisontotheresultsfromsimilarplants.AsSTPisapilot plant,thisisnotpracticable.TheapplicablesupportingrequirementsremainmetatcapabilitycategoryII.Therealisticplant-speci"cthermal-hydraulicsandothersupportinganalysis arelikelycapabilitycategoryIll.Theseclaimsarenottheresultofaconven-tionalpeerreview,butrathertheconclusionsofanin-depthindependentreview.Thisreviewwasconductedbyanindependenttechnicaloversightteamfromthe UniversityofIllinoisUrbana-Champaign.2.3.1.15APLAB,STPPRAModel-SuccessCriteria:Question1 STPResponse:(Item1,Page41)Section15.6.5.4.3oftheSTPUFSARnotesthatminimumsafetyinjectioncapacityisadequateforallbreaksbetween2-10inches;i.e.,1trainfailsand2 trainsstart,oneofwhichgoesoutthebreak.The2inchbreaksizeislimiting forPCT.Theanalysisperformedtojustifythisconclusionwasperformedinthe absenceofconsideringGSI-191phenomena.AnalysesperformedinsupportoftheLARincludedconsiderationofa6inchhotlegbreakwithonlyonetrainofECCSavailable.NotethatincasesinwhichTuesday1 stMarch,2016:19:32,Page241of393 DRAFTPART2.RAIRESPONSES(ROUND1)onlyasingletrainofECCSisavailable,switchovertohotleginjectionisnotperformed.TheevaluationincludedconsiderationofdebrisTheanalyses indicatethatthecoreisre"ooded,evenifdebrisblockstheinlettothefuel channels.ItisconcludedthatGSI-191phenomenadonotimpactthesuccesscriteriausedinthePRA.2.3.1.16APLAB,STPPRAModel-SuccessCriteria:Question2a STPResponse:(Item2a,Page41)ThebreaksizesandlocationsassumedintheRELAP5simulationswereconsistentwiththoseusedinthePRAandelsewhereinCASAGrande.2.3.1.17APLAB,STPPRAModel-SuccessCriteria:Question2b STPResponse:(Item2b,Page41)ThesuccesscriteriausedinthePRAformediumLOCAarebasedonanal-ysesre"ectedintheFSAR,namelythatatleastonetrainofECCSisavailable.

TheanalysesperformedforthecasewherealltrainsofECCSareavailable indicatethatboronprecipitationwillnotoccurformediumhotlegbreaks.ThesupportingthermalhydraulicanalysesperformedinsupportoftheLARalsoincludedconsiderationofa6inchbreakinthehotlegwithonlyonetrainof ECCSavailable.Theassumedbreakrepresentsthelimitingcaseforamedium hotlegLOCA,andtheconditionofasingletrainofECCSavailablerepresents pumpstate43.TheresultsoftheRELAP5analysisshowthatthecoreremains adequatelycooled.Inaddition,theliquidlevelinthecoreisquicklyrecovered, soboronprecipitationisnotcredibleinmediumLOCAscenarioswithlessthan threeECCStrainsavailable(assumingHLSOissuccessful).2.3.1.18APLAB,STPPRAModel-SuccessCriteria:Question2c STPResponse:(Item2c,Page41)LOCADMisacalculationtoolthatcanbeusedtoconservativelypredictthebuild-upofchemicalsdepositsonfuelcladdingafteraLOCAandtheon thecladdingtemperatureduetothechange(degradation)oftheoverallcladding conductivity.RELAP5-3Ddoesnothavethecapabilitytopredictthebuild-upofchemicalsdepositsonthefuelbutitiscapabletopredicttheeoftheconductivity degradationonthesurfacecladdingtemperature,giventhatthethicknessof thedepositanditsthermalconductivityisspeci"edasaninputparameterin thecoreheatstructure.AtthetimetheRELAP5-3Dmodelwasdevelopedand thethermal-hydrauliccalculations(speci"callythecoreblockageanalysis)were performed,thedepositionlayerwasnotincludedintheinputmodelofthecore heatstructure.Nevertheless,ifthefollowingcharacteristicsofthedepositlayer areassumed:

• Thickness=13.64mils(346.456lLm)(LAR:Volume3Paragraph5.10.1)

• ThermalConductivity=0.1Btu/(Ffth)(WCAP-16793-NP)theincreaseinisapproximately40F.TheconclusionisreachedthattheeofthedepositionlayeronthecladdingtemperaturedoesnotchangeTuesday1 stMarch,2016:19:32,Page242of393 DRAFTPART2.RAIRESPONSES(ROUND1)theoutcomeofthesimulationresultsperformedwiththeRELAP5-3Dmodelsforthecoreblockagescenarios.2.3.1.19APLAB,STPPRAModel-SuccessCriteria:Question3a STPResponse:(Item3a,Page42)CASAGrandeanalysesfortheSTPLARuseda36-hrperiodtoevaluatefailuremodesarisingfromdebrisaccumulationonthestrainerandonthecore.CASAGrandecomputestheparametersthatchangesigni"cantlyand/orhavepotentialimpactonpost-LOCAoperationwithinthe30daymissiontime.

However,STPparametricstudiesshowthatphenomenathatoccurwithinthe "rst18hoursessentiallyde"nethesuccessorfailureofpost-LOCAECCSop-eration.ECCSfailureprobabilitydoesnotincreasesigni"cantlyafter18hours.A36hours(2times18)analysistimewaschosenasareasonableanalysisperiodtoensurethetailendprobabilitiesareconsideredandtokeepCASArun timesalsowithinareasonableduration.Additionally,theconditionsandmechanismsassociatedwithdebrisareestablishedwithinthe"rst18-36hoursfromthestartoftheLOCA.There-foreatimerangeof36hoursprovidesthekeyparametersandbasisforconclud-ingECCSpost-LOCAsuccessorfailureandthereforeelyaddressesa30 daymissiontime.OtheranalysesperformedoutsideofCASAGrandeandtheir assumedaccidentdurationsareasfollows:Unquali"edCoatingsFailureTransport.Containmenttransportoffailedunquali"edcoatingsisconservativelymod-eledasbeingintroducedataconstantratefrom0to10minutes.Essentiallyall debrisisaccumulatedonthestrainerwithinafewpoolturn-overperiods.Hence by36hours,allofthecontributionfromthisparameterisconsidered.Notethat theactualtimerangeofUnquali"edCoatingsFailureandtransportis0min 30days.(SeeVolume3,Table5.5.5)DebrisTransport.100%ofdebristransportstotheactivesumpstrainersisconsideredtobecompletedwithin10hours,asveri"edbytrackingaccumulatedinventoryasa functionoftime.FormationofChemicalPrecipitants.Formationofchemicalprecipitantsisconsideredtooccurwithin10to20hoursfromthestartoftheaccident,baseduponthetemperaturepro"lesused andtheassumptionofaforcedprecipitationtemperature.(SeeVolume3,Figure

2.2.1)ChemicalStrainerheadloss,includingchemicalisassumedtoapproachanasymptoticvalueatapproximately2,000minutes,i.e.,33.3hours,afterthe LOCA.(SeeVolume3,Figure5.6.6)OperatorActions.OperatoractionssuchassecuringpumpsorswitchingovertohotleginjectionaremodeledconsistentwithEOPsandSAMGsConsequently,theeaccidentdurationusedbyCASAGrandetocal-culatetheconditionalprobabilityofsumpandcoreblockageis30days.Tuesday1 stMarch,2016:19:32,Page243of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.20APLAB,STPPRAModel-SuccessCriteria:Question3bSTPResponse:(Item3b,Page42)SensitivitystudieswereperformedontheCASAGrandeanalysisduration.Decreasingthesimulationtimefrom36hoursto24hourshadonlyanincidental onindicatingthatsuccessscenarioshadreachedasafe,stable endstate.Thefulleofchemicalprecipitateswasincludedforanyscenario meetingthebed-thicknessandprecipitationcriteriawithinthedurationofthe simulation,soinelong-termchemicalwereforcedtooccurwithin thetime-frameofinterestregardlessoftheactualtimeneededforcorrosionand precipitationphenomenatodevelopunderrealisticconditions.2.3.1.21APLAB,STPPRAModel-SuccessCriteria:Question3cSTPResponse:(Item3c,Page42)Thesafe,stableendstatecanbeunderstoodbyreferringtothemediumandlargeLOCAeventsequencediagrampresentedinVolume2,AppendixA, FigureA.3-1.Onlyonestableconditionisshown,andthatisontherightside ofsheet2ofthe"gure.Thestableconditionresultsifcoredamageisavoided.

Downbranchesinthe"gureindicatefailuresthatmayormaynotleadtocore damageendstatesdependingonsubsequentevents.Thecoredamageendstates areshownasredsymbols.Toreachtheone,safestableendstateinresponsetoamediumorlargeLOCArequires:

• Successfulreactortrip,*Successfulsafetyinjectionactuation,*MSIVclosureorturbinetriporthereactorwithstandingapotentialPTSovercoolingchallenge,*taccumulatorinjection,*LowheadpumpinjectiontotheRCS

• Highheadpumpinjection(notrequiredifalargeLOCA)

• Lowheadpumpsinsumprecirculationmode

• SumpavailableforrecirculationconsideringGSI-191issues

• Noin-vessel"owblockage

• Noboronprecipitationleadingtolossofcorecooling,and

• DecayheatremovalbyeithertheRHRheatexchangersorthecontainmentfancoolersIfthebreakisinthecoldleg,thensuccessfulhotlegswitchoverisalsorequiredinordertoavoidexcessiveboronprecipitation.Attheendofasafe, stablesequence,oneormorelowheadpumpsarealignedforsumprecirculation, atleastonetraintoanRCSloopviathecoldleg,and0,1,or2thehotlegsofthe remainingloops.AtleastonelowheadpumpmustbealignedtoanRCSloopTuesday1 stMarch,2016:19:32,Page244of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatremainsintact;i.e.toanRCSloopthatisnotwherethebreakislocated.Themostlikelysafe,stableendstateisthatallcontainmentfancoolersare operatingandthatcoolingtothesecondarysideofeachRHRheatexchanger alignedforlowheadpumpsumprecirculationisavailable.Thesearetheonly safe,stableendstatescreditedintheSTPPRAformediumandlargeLOCAs.2.3.1.22APLAB,STPPRAModel-SuccessCriteria:Question3d STPResponse:(Item3d,Page42)NochangesweremadetotheoutputsfromCASAGrandetoadjustforthePRAmissiontime.Theywerejudgedsuitableandusedasis.2.3.1.23APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3aSTPResponse:(Item3a,Page43)CASAGrandesamplesthepost-LOCAtimeatwhichonetrainofcontain-mentsprayissecuredfromdistributionsde"nedbytheuserforsmall,medium andlargebreaks.FortheSTPLAR,thesetimeswerede"nedasnormaldistri-butionswiththefollowingmeanandstandarddeviation:0

+/-0min.forSBLOCA(spraysneveron),20

+/-5min.forMBLOCA,and20

+/-5min.forLBLOCA.Sump"owratesandsump"owratedependentphysicalphenomenaaretheonlyplant conditionsthatthetimetosecureonesprayinputinthesimulation.

RWSTdraindowntimesareassignedpointvaluesforvaryingbreaksizes,calcu-latedwithtwocontainmentspraypumpsrunningbecausethesevaluesresultin themostprobablerecirculationswitchovertimes(LAREncl.4-3,Pg.33).Failed debriswashdownratesareassignedpointvaluestakenfromdeterministicanal-ysiswheretwocontainmentspraypumpswereassumedoperational(LAREncl.

4-3,Ref.23).DescriptionsofotherinputsandtheirassignmentinCASAGrande arelistedintheresponsetoAPLAB,CASAGrande-GeneralRAI1.Itisnotedthatstatisticalsamplingdoesnotprecludeselectionofaverylongtaskperformancetimethatelyrepresentsfailureofmanualactions.

However,nostrategiesareemployedtoensurethatthisconditionisalways representedinthestatisticaldesign.2.3.1.24APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3bSTPResponse:(Item3b,Page43)No,CASAGrandedoesnotmodeltheplantconditionsthatwouldoccuriftheoperatorsfailtosecurecontainmentspraylongtermoncecontainment pressureandiodinelevelsaresuitablylowi.e.,themanualactionsassociated withOFFSareunsuccessful.Speci"cally,CASAGrandesamplesthepost-LOCAtimeatwhichalltrainsofcontainmentsprayaresecuredfromdistributionsde"nedbytheuserfor small,mediumandlargebreaks.FortheSTPLAR,thesearede"nedasnormal distributionswiththefollowingmean,standarddeviationandtruncationlimits:

390+/-5min.between390and420min.forSBLOCA,390

+/-10min.between390and420min.forMBLOCA,and390

+/-15min.between390and450min.forLBLOCA.Forthesecases,thetruncationlimitsprecludeperformancetimes beyond450min.(7.5hr).Plantconditions(ie.sump"owrates,washdownrates,Tuesday1 stMarch,2016:19:32,Page245of393 DRAFTPART2.RAIRESPONSES(ROUND1)RWSTdrain-downtimes,etc.)arenotmodeledfortheconditionwhereoperatorsfailtosecurelong-termcontainmentspray.2.3.1.25APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3cSTPResponse:(Item3c,Page43)ThePRAmodeldoesincludelogictorepresentfailuretotriponerunningcontainmentspraypumpaswellasfailuretotripallcontainmentspraypumps lateinthesequence.However,therearenoresultsfromCASAGrandethatare representativeofthesefailureconditions.Failuretotriponerunningcontainment spraypumpearlyinthesequencewouldresultinthedebrisbeingapproximately evenlydividedamongthethreesumpstrainerswithacorrespondinglowerhead lossthaninthecaseofonlytworunningcontainmentspraypumps.Sincefailure ofonestrainerisassumedtoresultinfailureofallstrainers,thisapproach isconservativeforstrainerheadloss.However,theapproachmaybeslightly unconservativewithrespecttoin-vesseleastheadditionaldebrisonthe strainerwouldprovidemore"ltration.2.3.1.26APLAB,STPPRAModel-PRAScope:Question2 STPResponse:(Item2,Page45)IntheresponsetoAPLAB,STPPRAModel-PRAScope:RAI1(STPletterprovidedtoNRCSNOC-AE-14003103,May22,2014,ML14149A434 page24),itwasestablishedthatthemeanfrequencyofaseismicallyinduced MediumLOCAisestimatedtobe1.08x10-7peryear.Theboundingassumption ofaconditionallikelihoodof0.1forrecirculationfailurefollowingaseismicevent suggeststhecontributiontomeancoredamagefrequencyduetoaseismically inducedMediumLOCAisnogreaterthan1

.1x108peryear.2.3.1.27APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1aSTPResponse:(Item1a,Page46)Keysourcesofmodeluncertaintyare:

• Successcriteriaforfuelblockageandboronprecipitation

• Fiberpenetrationofthesumpstrainer

• Headlosscorrelationatsumpstrainer

• Debrisgeneration,includingsizeandshapeofzoneofin"uence

• Debristransporttothesump

• Abilityofchemicalprecipitatestocauseincreasedstrainerheadlossandfuelblockage2.3.1.28APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1bSTPResponse:(Item1b,Page46)Keyassumptionsmadeare:Tuesday1 stMarch,2016:19:32,Page246of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• Adiscretesetofoperabilitystatesofthepumpstakingsuctionfromthecontainmentsumpwasadopted.Inagivenscenario,thespeci"ccon"gu-rationofoperatingpumpswasboundedbyaonememberofasetof"ve analyzedcases.Ifaspeci"cpumpcon"gurationwasnotboundedbyone ofthe"veanalyzedcases,coredamagewasassumedtooccur.

• Failureconditionsfoundatoneormoreofthethreecontainmentsumpswasassumedtoresultinfailureatallthreesumps.

• Forcoldlegbreaks,itwasassumedthatboronprecipitationwouldbepossiblewithouthotleginjectionswitchover.

• Alargezoneofin"uenceforjetinduceddebrisgenerationwasassumed.

• Whenincreasedbyafactorof5,theNUREG/CR-6224isexpectedtoboundconventionalheadloss.

• Itwasassumedthatnocorebypasscapabilityisavailableforblockageexceeding7.5gperfuelassembly.

• Nocredittakenforcorebypass.2.3.1.29APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1cSTPResponse:(Item1c,Page46)Theadaptationofdiscretepumpoperabilitystateslikelyhadamodestcon-servativeimpactontheresultsforLargeLOCA.However,thisassumptionhad amoresigni"cantconservativeimpactintheassessmentofMediumLOCAs.

100%ofthereportedcontributionofsumpfailureforMediumLOCAswasdue tosequenceswithpumpoperabilitycombinationsthatwerenotboundedby the"veanalyzedpumpstates.Ifa"nermoredetailedsetofpumpstateswere chosen,thenthecalculateddeltaCDFwouldbelower.Theassumptionthatfailureconditionsatonesumpwouldresultinfailureatallsumpsisconservative.Theheadlosscorrelationused,includingbumpupfactors,isconservativebasedontheresultsoftheSTP-speci"cheadlosstests.TheassumptionthatboronprecipitationfollowingMediumcoldlegbreaksislikelyconservative.Thelargezoneofin"uencefordebrisgenerationisboundingandpossiblyconservative.TheassumptionthatbreaksoccuronalegequippedwithSIyieldsaslightlyconservativeresult,asthereisonlya1/4likelihoodthatthebreakwouldbeon thelegwithoutSI.PleaseseetheresponsetoAPLAB,ResultsInterpretation-UncertaintyAnal-ysis:RAI6foradditionaldescriptionofthesensitivityanalysesconducted.2.3.1.30APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion3STPResponse:(Item3,Page47)AsdescribedintheLAREnclosure4-1,Section2.1.2,allSTPlarge-borepipingPWSCC-susceptiblewelds(nozzlewelds)havebeenreplacedorother-wisemitigated,withtheexceptionofthereactorvesselnozzlewelds.AsfurtherTuesday1 stMarch,2016:19:32,Page247of393 DRAFTPART2.RAIRESPONSES(ROUND1)described,thereactorvesselnozzleweldsarelessofaconcernintheGSI-191analysisthanareotherbreaklocationsbecausethereactorvesseliscovered withRMI,andtheprimaryshieldwallwouldprotectthemajorityof"berglass insulationinthesteamgeneratorcompartments.Finally,STPNOCiscurrently incompliancewithASMESectionXIweldinspections.BothSTPplantsareatapproximately25yearsofserviceandthereforeitisappropriatetoexpectthatthe25-yearLOCAfrequencyvalueswouldapply.It isfurtherreasonableto"reset"theeetimeofservicetomuchlessthan25 yearswhentakingintoaccountthemostproblematicweldshavebeenmitigated orreplaced.The40yearestimatesforCDF,LERF,andareprovidedinEnclosure5.Thefollowingtablesummarizesthe40yearestimates.Table2: defaultParameterValueCDF2.20E-05LERF1.38E-06 6.85E-08 1.12E-102.3.1.31APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4aSTPResponse:(Item4a,Page47)QuantileswereelicitedinNUREG-1829atthe5th,50th,and95th.Themeanvalueswerenotelicitedbutinstead,werederivedfromasplitlognormal distributionfortheelicitedquantiles.ThedistributionsusedintheLARwere developedtomostclosely"tthevalueselicitedintheexpertelicitationprocess.

AsdescribedinEnclosure6,becausethemeanvaluesareusedbythePRA fortheinitiatingeventfrequencies,andLERFactuallyusethemean valuesfromNUREG-1829.2.3.1.32APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4bSTPResponse:(Item4b,Page47)ThealgorithmusedtosolvethatmodeltakesasinputinitialvaluesfortheJohnsonparametersasastartingpointfortheoptimizationalgorithm.For eachcategory,thevalueofthelowerbound,,oftheJohnsondistributionwasinitializedtohalfofthe5thpercentilegiveninNUREG-1829,andtherange,,wasinitializedtotwicethe95thpercentile.Thiswasdonetoproduceadditional spreadofthedistributionoutsidetheNUREG-1829percentilesandthereby capturingareasonablerangeofuncertainty.AlternativeJohnsondistributions couldbeobtainedbyrangingtheJohnsonscaleparameter,,that"tthethreepercentileselicitedfromexpertsaspartofNUREG-1829asshowninEnclosure7.

AlthoughJohnson"tscanbeobtainedwithhighermeanfrequencies,increasing thescalefactortoafactorof100timesthe95thpercentileofthefrequencies elicitedfromexpertsinNUREG-1829produceslessthana2%increaseinTuesday1 stMarch,2016:19:32,Page248of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.33APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4cSTPResponse:(Item4c,Page48)AsshowninEnclosure8changesinCDF,LERF,andaremodestwhentheJohnsonscaleparameter,,israngedfromafactorof1.25uptoafactorof100timesthe95thpercentileofthefrequencieselicitedfrom expertsinNUREG-1829.(Afactorofabout2.00wasusedinSTPssubmittal.)

Morespeci"cally,pointestimatesofandincreasebynomore than2%forthespeci"cvaluesofconsideredinEnclosure8.EstimatesofCDFandLERFdfromandLERFbyvaluesthatdonotdependon.2.3.1.34APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4dSTPResponse:(Item4d,Page48)Thedistributionsderivedfromthe"ttedboundedJohnsondistributionswerescaledforuseinthePRA.Thiswasdonetomatchtheresultingmeanvalues withthemeansinterpolateddirectlyfromNUREG-1829.2.3.1.35APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion5STPResponse:(Item5,Page48)TheCASAGrandeevaluationofGSI-191failurephenomenaispartlyde-pendentontheLOCAfrequencyuncertainties,butnotontheabsoluteLOCA Frequencyestimates.Theallocationofbreaksizes,withinCASAGrande,is dependentonthedownwardslopeoftheLOCAexceedancefrequencieswithin thebreaksizerangebeinginvestigated.Thechangeinslopewithinthesmall, medium,orlargeLOCAbreaksizesdictatestheweightsgiventothedt breaksizesonlywithinthesizebeinginvestigated.Thebreakfrequenciesat everybreaksizecouldbemultipliedbyafactor,andtheestimatesfromCASA Grandewouldnotchange,becausetherelativeallocationofbreakfrequency toeachsub-intervalwithin,saytheLargeLOCA,breaksizerangewouldnot change.ForthePRA,thecoredamagefrequencydependenceisontheinfrequencyattwopointsontheLOCAfrequencyexceedancecurve.Multiplying theLOCAfrequencyatthetwopointsbyafactorwouldchangethebreak intervalfrequencybythatsamefactor.Thereisnodependenceonthevarying slopewithinthetwobreaksizes,onlytheontheoverallfrequencydBoththePRAandCASAGrandeusethesamebreaksizeintervalsandthisisaccountedforinboth.WebelievethisdependenceofthePRAandCASA GrandeontparametersoftheLOCAbreakfrequenciesistso astonotwarrantcorrelationbetweenthePRAandCASAGrande.2.3.1.36APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion6STPResponse:(Item6,Page48)Asensitivityanalysiswasperformedby1)developingthescopeofpoten-tiallyimportantcontributorstoandthen2)analyzingtheirindividual contributionsinaone-waysensitivitystudy.ThestudywasthenexpandedtoTuesday1 stMarch,2016:19:32,Page249of393 DRAFTPART2.RAIRESPONSES(ROUND1)includeaggregatecontributionsfromthetwohighestcontributors,"berpen-etrationthroughtheemergencycorecoolingsystemstrainersandthesuccess criteriaforboronprecipitation(boron"berlimit).Therestofthecontributions werejudgedtobelessimportantintheaggregatebasedontheone-wayanalysis.

TheCDFestimateismostsensitivetothreeparametersthatconcern:1)how muchdebrisisrequiredtotriggeranin-vesselfailure(boron"berlimit),2)the fractionofdebristhatpenetratesthesumpstrainer("berpenetrationfunction),

and3)thefractionofdebrisofttypesthatistransportedfrom entlocationsduringdtoperationalphases(debristransportfractionsin ZOI).Theeoftheboron"berlimitexceedsthatofthenextmostsensitive parameterbyanorderofmagnitude.Ananalysisofthesensitivitytotheaggre-gateofthebypassfractionandboron"berlimitisshowninthefollowing

"gure.Tuesday1 stMarch,2016:19:32,Page250of393 DRAFTPART2.RAIRESPONSES(ROUND1)EnclosurestoAttachment1APLAB,CASAGrande-PlantCon"guration:RAI3Enclosure1-ResponsetoAPLAB,CASAGrandePlantCon"guration:RAI3PlantCon"guration:

CombinationsofPumpFailuresAPLAB,STPPRAModel-GeneralRAI-1Enclosure2(A)-AttachmentAtoCR07-1684ResolutionofPRAHRAUpdateReportPeerReviewFact/Ob-servation(F&O)Comments Enclosure3(B)-LevelBobservationsresolved Enclosure4(C)-IndependentReviewoftheElectricPowerRecoveryAnalysisAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI3Enclosure5-ResponsetoAPLAB25vs40YearFrequencyEstimates:RAI3APLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4aEnclosure6-ExplanationoftheDiscrepancyinMeanLOCAFrequenciesforFittedJohnson DistributionversusNUREG-1829ValuesAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4bEnclosure7-ExplanationoftheJohnsonDistributionGoverningLOCAFrequencyand SensitivityofSummaryStatisticstoScaleParametersAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4cEnclosure8-ExplanationoftheImpactofJohnsonDistributionSelectiononCDF,LERF, LERF2.3.2ACRBResponses 2.3.2.1ARCB:Question1 STPResponse:(Item1,Page49)TheresponsetoARCB,RAI1wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.2.2ARCB:Question2 STPResponse:(Item2,Page49)TheresponsetoARCB,RAI2wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.2.3ARCB:Question3 STPResponse:(Item3,Page50)TheresponsetoARCB,RAI3wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.3EMCBResponses 2.3.3.1ECMB,Question1 STPResponse:(Item1,Page50)TheresponsetoEMCBRAI1wasprovidedintheSTPlettertoNRCdatedDecember23,2013,NOC-AE-13003065,ML14015A311.Tuesday1 stMarch,2016:19:32,Page251of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.3.2EMCB,Question2STPResponse:(Item2,Page51)ResponsetoEMCBFollow-upRAIdatedJune2,2014ThetwocasestabulatedinNOC-AE-13003065asCases1and2usedtialpressuresof2.47psiand4.00psi,respectively.CaseIisforthehigh temperaturecaseof2670F.Case2isforthelowtemperaturecaseof1280F.ThestrainerloadusedforCase1is5.71ftwhichisequivalentto2.47psiusingadensityvalueof62.4lbpercubicfeet(coldwaterdensitywasconserva-tivelyused).ThestrainerloadusedforCase2is9.35ftwhichisequivalentto 4.0psiusingadensityof61.58lbpercubicfeet.Deterministicanalysisshowedthatthestrainersdonotfailunderanydesignbasisloadingcondition.ThoseresultswereprovidedinthetabulatedIRvalues previouslysubmitted.Asnotedinthequestion,allIRvalueswerelessthan one.UnlikeDeterministicanalysis,Probabilisticanalysisconsidersfailuretobe alwayspossibleandattemptstoquantifytheprobability.FortheProbabilistic analysis,"failure"isde"nedtobeanyscenariowitharesultingdtialpres-suregreaterthan9.35ft(thehighestanalyzedinthestructuralquali"cation calculationwhichusesCodeallowables).SinceCodeallowablesincludeconsid-erablemargintoactualphysicalfailure,thisde"nitionoffailureisconservative.TheproposedchangetotheUFSARis:

6.2.2.2.3ContainmentEmergencySumpDescriptionAtthebeginningoftherecirculationphase,theminimumwaterlevelabovetheContainment"oorisadequatetoprovidetherequiredNPSHfortheECCS andCSSpumps.ThesumpsaredesignedtoRG1.82,proposedRevision1,May 1983andwithconsiderationofthedebrisidenti"edinGenericLetter 2004-02,asdescribedinAppendix6A.Thesumpstructuresaredesignedto limitapproach"owvelocitiestolessthan0.009ft/secpermittinghigh-density particlestosettleoutonthe"oorandminimizethepossibilityofcloggingthe strainers.Thesumpstructuresaredesignedtowithstandthemaximumexpected tialpressureimposedbytheaccumulationofdebris.Therisk-informedmethodologyappliedtoevaluatetheriskassociatedwithctsofdebrisshows thattheincreaseinriskassociatedwithdebristhatwouldexceedthedesignlimitsofthesumpstructuresisverysmall,inaccordancewiththeacceptancecriteria ofRegulatoryGuide1.174.2.3.4ENPBResponses2.3.4.1ENPB,Question1 STPResponse:(Item1,Page51)AsdescribedinseveralplacesintheLAR(forexample,Enclosure4-1,Sec-tion2.3.5,Enclosure42,Section2,andEnclosure4-3,Section5.3)theEPRI RI-ISIfrequenciesarenotusedtodirectlydevelopLOCAfrequencies.NUREG 1829(Enclosure4-3,Reference[37]),frequenciesareusedasthebasisforLOCA frequenciesandtheEPRIRI-ISIfrequenciesareonlyusedasweightstodis-tributetheNUREG1829frequenciesmoreheavilytolocationswheredegrada-tionmechanisms(DMs)areknowntobepresent.Thefollowingsummarizesthe processusedtoidentifytheDMsusedintheLAR.TheassessmentofDMsusceptibilityisperformedinthreesteps:1.IndependentreviewofthedegradationmechanismevaluationperformedTuesday1 stMarch,2016:19:32,Page252of393 DRAFTPART2.RAIRESPONSES(ROUND1)fortheSTPRI-ISIProgram[1,2,3,4]2.SystematicreviewofthecurrentworldwideserviceexperiencewithCodeClass1pipinginWestinghousePWRplants,and3.ReviewofrelevantindustryreportsonmaterialdegradationDMsusceptibilityscreeningcriteriaareappliedtodetermineapplicableDM-susceptiblelocationsasreferencedinEPRITR-112657.OnlythoseDMsthat applytotheenvironmental,stress/loadconditions,andmaterialtypesthatare foundintheSTPreactorcoolantpressureboundarypipingareincluded.

References:

1.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlternativetotheASMEBoilerandPressureVesselCodeSectionXIExamina-tionRequirementsforClass1PipingWelds,RR-ENG-2-16,December1999.

2.StructuralIntegrityAssociates,Inc.,DegradationMechanismEvaluationfor theSouthTexasProjectElectricGeneratingStation(STPEGS)Units1and2, EPRI-116-330,Rev.0,December1999.

3.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlter-nativetotheASMEBoilerandPressureVesselCodeSectionXIRequirements forClass1SocketWeldedPipingandClass2PipingWelds,RR-ENG-2-23, February2001.

4.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlter-nativetotheASMEBoilerandPressureVesselCodeSectionXIRequirements forClass1andClass2PipingWelds,RR-ENG-3-04,September2011.2.3.4.2ENPB,Question2 STPResponse:(Item2,Page51)Theinitiatingfrequenciesforthe1.5-inchand2-inchpipesizesforCategory6AwereduplicatedintheCASAGrandeanalysis.Theinitiatingfrequenciesforthe0.75-inchand1-inchpipesizesforCategory6BwereduplicatedintheCASAGrandeanalysis.Theinitiatingfrequenciesforthe1.5-inchand2-inchpipesizesforCategory8CwereduplicatedintheCASAGrandeanalysis.ThefrequenciesinSection2.2.3areusedinconjunctionwiththeweldcountsinSection5.3.1.2.3.4.3ENPB,Question3 STPResponse:(Item3,Page51)TheLOCAfrequenciesassociatedwiththeweldsintheLARanalysisarenotspeci"callyadjustedfor"awsfromtheSTPISIprogram.LOCAfrequencies areusedintwowaysintheanalysis:1)toforminitiatingeventfrequenciesin thePRAand2)toconstructajointprobabilitydistributiongoverningbreaksize andweldinCASAGrande,conditionalonaLOCAevent.For1),noadjustment ismaderelevantto"awsormitigation;thosefrequenciesaretakenfromNUREG 1829directly.Inthecaseof2),withinabreak-sizecategorythelikelihoodfor abreakataparticularweldisweightedtotakeintoaccountdegradationor mitigation,buttheprobabilityofhavingabreakineachcategorymatchesthe correspondingNUREG1829frequency.Tuesday1 stMarch,2016:19:32,Page253of393 DRAFTPART2.RAIRESPONSES(ROUND1)Therefore,NUREG1829frequenciesarepreservedintheevaluationforanygivenbreaksizeinaweightingscheme.ThemethodreferredtoastheLOCA-Hybridmethod(seetheLOCA-HybridFinalreport,ML12145A466,2012)as summarizedintheLAR(forexample,Enclosure4-1,Section2.3.5,Enclosure 4-2,Section2,Enclosure4-3,Section5.3)weightsthefrequencymoreheavily onweldswithhigherpotentialfor"aws.Theweightsarederivedbasedonan industry-widedatabaseofin-serviceinspectiondataforweldtypes,andlarger weightsaregiventotheproblematicweldtypesrelativetothosewithfewer"aws

detected.Weldsthathavebeenmitigated(replacedwithrobustweldmaterial,forexampleAlloy690,ormitigatedwithweldoverlay)areweighted(again,based onindustry-widedata)lessheavilyintheLOCA-Hybridmethod.Bothtypes oftheseweldsareinserviceatSTP,howeveronlytheweldsthatwereoverlaid onthepressurizersafeendshavebeenweightedaccordinglyintheanalysis toaccountfortheweldoverlays.Morede"nitiveexplanationofthedetailed implementationoftheLOCA-Hybridmethodhasbeenprovidedintheresponse toAPLABCASAGrande-LOCAFrequencies:RAI4,STPlettertotheNRC datedMay22,2014,ML14149A434.2.3.4.4ENPB,Question4STPResponse:(Item4,Page52)TheSTPapproachtoestimatingLOCAfrequencieswouldnotchangeasaresultofSectionXIinspection.LOCAfrequenciesaredeterminedusingthe methodologydescribedintheLOCA-HybridapproachintheresponsetoAPLAB, CASAGrandeLOCAFrequencies:RAI1providedintheSTPlettertotheNRC datedMay22,2014,ML14149A434.2.3.4.5ENPB,Question5STPResponse:(Item5,Page52)a)TheentriesinTable2.2.3de"nethedistributionofannualfrequencyoverbreaksizeforeachweldcase.The12breaksizesidenti"edinLAREnclo-sure4-3,Table2.2.3arenotusedforthesamepurposeasthe13break sizerangesplottedinFigure5.3.4.Therefore,theycannotbecompared directly.The12breaksizeswiththeirrespectivefrequencieslistedinTable2.2.3areembeddedinthecomplementaryannualfrequencydistribution(blue curve)ofFigure5.3.4.TheverticaldashedandsolidlinesinFigure5.3.4 displaythe13samplingbinsfromwhichrandombreaksizesarechosen forCase1B.Thenumberofsamplingbinsdistributedineachbreaksize categoryiscalculatedwithEquation25and26(LAREnclosure4-3,Page 150).Acompleteexplanationforhow13samplingbinsareidenti"edfor Case1BisprovidedinSection5.3.5ofLAREnclosure4-3.Horizontallinesillustratetheannualfrequencyweightscarriedbyeachbreaksizerange.Theweightforeachbreakscenariois calculatedastheoftheupperandlowercomplemen-taryannualfrequenciesthatcorrespondtotheboundsofeach samplingbin(positivedofthehorizontallines).Tuesday1 stMarch,2016:19:32,Page254of393 DRAFTPART2.RAIRESPONSES(ROUND1)b)Therearemanypossiblescenariosforselectingasetofbreaksizesateachweld.ThescenarioillustratedinFigure5.3.4(Volume3,Rev.2,Pg.151) isbuiltonthecomplementaryannualfrequenciesofTable2.2.3(Volume3, Rev.2,Pg.35)andrepresentsanonuniformstrati"edsamplingstrategy.

ThebreaksizedistributionschemeinFigure5.3.4providescon"dence andassurancethatthebreakselectionwillresultinappropriatedebris generationbyassigningagreaternumberofbinsforlargerbreaksizes.This practiceensureshighersamplingresolutionofthevery-low-frequencytails wherelargebreaksgeneratemoredebrisandaremorelikelytochallenge ECCSsafetysystems.Althoughmanymorepotentialfailurescenariosare examinedbythisstrategy,noover-conservatismisintroducedbecausethe correspondingweightingfactors(positivedofhorizontallines)are proportionallysmallerwherethesamplingresolutionishighest.Rearrangingthenumberofbinsineachcategorymaycausetresolutionofthetail,ifthelessprobableregion(LargerBreaks)hasfewer binsthantheothercategories.Notein"gure5.3.4thatboththebreak sizeandthecomplementaryannualfrequenciesareplottedonlogarithmic scales.Ifaverycoarsesizeresolutionischosenforthelarge-breakrange, theremaybeavanishinglysmallchancethatanybreaksapproachingthe DEGBconditionwillbeselectedatrandom.Thebreaksizedistribution intheCASAGrandeanalysisisneithertooconservativenorisitnon-conservativeintermsofthedebrisgenerationbecause(1)apredominance oflargerbreakscenariosareexaminedateveryweldforpossiblefailure and(2)strati"edsamplingwithnon-uniformweightingensuresastatisti-callyunbiasedestimateoffailureprobability.Non-uniformsamplingisa commonvariancereductiontechniqueforestimatinglowprobabilityevents whereitisbettertohaveatleastafewfailureeventswithsmallweighting factorsthantohavenofailureeventsatall.2.3.4.6ENPB,Question6aSTPResponse:(Item6a,Page52)TheLOCAfrequencyestimatesareconsistentwithNUREG-1829asde-scribedintheresponsetoAPLAB,CASAGrandeLOCAFrequencies:RAI1 providedintheSTPlettertotheNRCSdatedMay22,2014,ML14149A434.

TheseestimatesaretthanthosethatwouldbeprovidedbytheEPRI RI-ISIprogram.AdditionalexplanationsareprovidedinresponsetoEPNBRAI

6b.2.3.4.7ENPB,Question6bSTPResponse:(Item6b,Page53)NUREG-1829LOCAfrequenciesareusedinthePRAasthebasisforLOCAfrequency.TheRisk-InformedISIprogramhas,asitspurpose,schedulinginspec-tionsbasedontheexpectationfor"ndinga"awforthepurposeofmitigation.

ThestatisticalbasisisthereforeinappropriateforLOCAfrequencyestimates.ThedinthefrequencyestimatesbetweentheGSI-191submittalandtheRI-ISIprogramarediscussedinmoredetailintheattachedreport entitledEPNB-ConsistencyofWeldFrequencieswithRI-ISIProgram,Revision 1(Enclosure1).Tuesday1 stMarch,2016:19:32,Page255of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.5ESGBResponses2.3.5.1ESGB,ChemicalQuestion1a STPResponse:(Item1a,Page53)Althoughchemicalhavenotbeenfoundtobesigni"cantcontributorstoSTPpost-LOCAsumpconditions,CASAGrandeevaluatesachemicalcon-tributionbasedonbreaksizetoprovidesafetymarginintheanalysis.Twolevels ofpossiblecorrelationbetweenconventionalandchemicalinducedheadlosscan bede"ned:(1)therelationshipbetweenconventionaldebrisheadlossandthe attributesofthechemicalhead-lossfactordistributionsappliedacrossLOCA categoriesofSBLOCA,MBLOCA,andLBLOCA,and(2)therelationshipbe-tweenconventionaldebrisheadlossandvaluesofthechemicalhead-lossfactor sampledfromwithinaLOCAcategory.TheLARanalysisdoesincludethe"rst typeofcorrelationbyapplyinglargerchemicalhead-lossfactorstolargerbreaks wheretheconventionaldebrisheadlossisalsoexpectedtobehigher.TheLAR analysisdoesnotenforcethesecondtypeofcorrelation(directcorrelationbe-tweenconventionaldebrisheadlossandchemicalhead-lossfactorssampledforscenarioswithinaLOCAcategory).Uncorrelatedsamplingspreadsthevari-anceoftheexponentialchemicalhead-lossdistributionsacrossallbreak sizesandintroducesanopportunityforsmallbreakstoreceivelargechemical head-lossfactors.ResponsesESGBRAI5andESGBRAI1ddiscussthepos-sibleofenforcinganinversecorrelationbetweenbreaksizeandchemical head-lossfactor.Althoughbothtypeofprecipitateand"lteringcharacteristicsofthedebrisbeddototalheadloss,head-lossfactorsdescribedinLAREnclosure4-3, Table5.6.4wereusedintheCASAGrandeanalysisbecausethedistributions applyvaluesderivedfromthemultiplicativeresponseofaSTPdesign-basis debrisbed(DBA)tothemaximumchemicalload(LAREnclosure4-3,Reference

[53],[1])asdescribedintheresponsetoESGBRAI1c.However,totalhead lossassessedbytheCASAGrandeanalysismaybeunderestimatedforthin bedcases.Thinbedcasesmayhavesmallconventionalheadlossbutstillhave relativelylargechemicalheadloss.Suchheadlossesmaybeashighasthose measuredinSTPDBA(bounding)conditions[Enclosure1,Section4.1and

4.5].Giventhispossiblediscrepancy,analternativeadditivechemically-inducedheadlosscalculationwasperformed[Enclosure1].Thecalculationmethodin-corporatesboththetypeofprecipitateandSTPDBAdebrisbed-per-surface arearesponsetoquantifytotalheadloss.Resultsofthisalternativecalculation supporttheconclusionthatthehead-lossfactorapproachappliedintheLAR islikelyconservativeforconditionswithhighconventionalheadloss[Enclosure 1,Section4.5],butalsodemonstratesthesuspectedunderestimationoftotal headlossforsmallerbreaksfromapplicationofsmallerhead-lossfactorsthan theLBLOCAhead-lossfactor[Enclosure1,Section4.1andSection4.5].How-ever,thisalternativecalculationalsodemonstratesthatadditionofamaximum chemically-inducedheadlossresponseresultingfromprecipitatemassesgener-atedbyWCAP-16530-NPreleaseequationstoconventionaldebrisheadlossmay notincreasefailures[Enclosure1,Section4.5],andtherefore,theriskestimate islargelyunchanged.Tuesday1 stMarch,2016:19:32,Page256of393 DRAFTPART2.RAIRESPONSES(ROUND1)

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.2ESGB,ChemicalQuestion1b STPResponse:(Item1b,Page53)HistogramsofchemicalheadlossvsfrequencyforCASAGrandeCase01(allequipmentoperates)arepresentedbyFigures1and2.Ofthelargebreaks analyzedinCase01,only77%formedathinbedorlargerandtheresulting chemicalheadlossforalllargebreaksrangedbetween0and154.9ftasshown byFigure1.OfthemediumbreaksanalyzedinCase01,1.3%formedathin bedorlargerandtheresultingchemicalheadlossforallmediumbreaksranged between0and0.14ftasshownbyFigure2.SmallbreakLOCAarenotlisted becausenoneofthecasesanalyzedinCASAGrandeCase01formedathinbed orgreater.Figure1:Largebreakchemicalheadlossasafunctionofrelativefrequency(logscale)2.3.5.3ESGB,ChemicalQuestion1cSTPResponse:(Item1c,Page53)Thesingle-parameterexponentialPDFwaschosenforshapeandforconve-nienceof"ttingthedesiredstatisticsofthemeanandatruncatedtailproba-bility.TheexponentialPDFwasnotselectedtomatchanunderlyingphysical process(exponentialPDFiscommonlyusedtodescribetimebetweenfailures) ortoreplicatealargebodyofdata.Inthisapplication,theexponentialPDF isappliedasasubjectiveprobabilitydistributionthatplacesthehighestprob-abilityneartheminimumchemicalhead-lossfactorof1.0andrapidlydeclines acrossallpositivevalues.OtherPDFsincludingWeibull,gammaandbetathat supportunimodal,monotonicallydecliningshapescouldhavebeenadaptedfor thispurpose.Thefollowingdiscussionexplainshowtheexponentialstatistics werespeci"ed.Tuesday1 stMarch,2016:19:32,Page257of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:Mediumbreakchemicalheadlossasafunctionofrelativefrequency(log scale)ThestandardexponentialPDFwasadaptedforusewiththemultiplicative(chemical"bumpup")approachdescribedinLAREnclosure4-3.First,addition ofchemicalstoa"berbedshouldneverreduceexistingheadlossassociated withconventionaldebrisaccumulationattheECCSstrainer,sothePDFwas shiftedtoaminimumfactorof1.0(one).Also,STPCHLEtestswithrepre-sentativealuminumand"berglasssurface-areatowater-volumeratiosindicated thatprecipitationofchemicalproductswasunlikely(LAREnclosure4-3Refer-ence[18-19])WhiletheSTPCHLEtestdonotcoverthefullspaceofLOCA scenarios,theSTPCHLEtestsdosimulatethemostprobablecasesexpected withinthemediumandlargebreakcategories.Therefore,amultipliercloseto 1.0(one)de"nedasthemodeoftheshiftedexponentialPDFrepresentsthe mostprobablecases.ThemeanoftheexponentialPDFwasdeterminedfromevaluationofSTPECCSstrainertesting(LAREnclosure4-3,Reference[53]).Thedesign-basisde-brisbed,havingmaximumdebrisvolumeandmassassociatedwitha7DZOI, wasdeterminedtobethe"bounding"scenarioforSTPbecausethequantityof debrisobservedonthestrainersurfacewassigni"cantlylessthan1/8thick; thereforetheassessmentofathinbedwasunnecessary(LAREnclosure4-3, Reference[53]).Theappliedchemicalprecipitatetestloadwasrepresentativeof precipitatequantitiesgeneratedfrom30-day,continuoussprayexposureofdeter-ministicallyboundingmaterials(1,Table6.3-7).Chemically-inducedheadloss attributabletotheworstcaseprecipitateloadincreasedthedesign-basiscon-ventionalheadlossbyafactorof2.25(LAREnclosure4-3,Reference[53]).For addedconservatism,theSBLOCAmeanwassetequaltothisobservation,while MBLOCAandLBOCAmeanswereincreasedto2.5and3.0,respectively.In thiscontext,conservatismisappliedbecausetheassignedexpectations(means) arehigherthantestdataindicate.ThemaximaoftheexponentialPDFswerecon"rmedtobevaluescapableofproducingaquanti"ablenumberofchemicallyinducedfailuresincombina-Tuesday1 stMarch,2016:19:32,Page258of393 DRAFTPART2.RAIRESPONSES(ROUND1)tionwiththespectrumofconventionalheadlossexperiencedwithineachbreaksize.Thisapproachisjudgedacceptablebecausethemeansforeachbreaktype alreadycapturechemicallyinducedheadlossattributabletoaboundingprecip-itateloadobservedacrosstheboundingdebrisbed.Themaximumfactorsfor SBLOCA,MBLOCA,andLBLOCAchemicalheadlosswere6.8,8.1,and10.7 timeslarger,respectively,thanthe2.25factorincreaseofmaximumheadloss observedintestingunderdesign-basisconditions.Regardingdevelopmentofthesingle-parameterexponentialdistributions,onlythemeanisneededtofullyspecifythedistribution;sothemaximumwas manuallycon"rmedasbeingreasonabletorepresentalllargerfactorswitha cumulativetailprobabilityof1E-5.Themaximumwasnotimposedasanaddi-tionalconstraintonthedistributionitself.

Reference:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.4ESGB,ChemicalQuestion1d STPResponse:(Item1d,Page53)MeansoftheexponentialPDFsweredeterminedfromevaluationofSTPECCSstrainertesting(LAREnclosure4-3,Reference[53])asdiscussedinthe ESGBRAI1cresponse.Insummary,chemically-inducedheadlossobservedin theSTPECCSstrainertesting,attributabletothecompleteadditionofthe worstcaseprecipitateload[1],increasedthedesign-basisconventionalheadloss byafactorof2.25(LAREnclosure4-3,Reference[53]).TheSBLOCAmean wassetequaltothisobservation,whileMBLOCAandLBLOCAmeanswere increasedto2.5and3.0,respectively.AssigningLBLOCAandMBLOCAhigher meansandsettingtheSBLOCAmeanequaltothetestobservationprovides conservatismbecausetheassignedexpectations(means)arehigherthanSTP design-basisstrainertestdataindicate.TailsoftheexponentialPDFsprovide forevenhigherchemicalconsistentwithobservationsofthin-bed strainertests.Analysisofchemically-inducedheadlossusinganadditiveapproachde-scribedinEnclosure1thatcalculatesECCSstrainerheadlossasafunction ofbothprecipitatetypeandSTPdesign-basis-debrisperstrainerareaindicates thatthemeanheadlossfactorusedinthechemicalmodel(LAR,Enclosure 4-3,Section5.6.3)shouldlikelyincreasewithdecreasingbreaksize[Enclosure 1,Section4.1and4.5].TheresultsobtainedbyEnclosure1arealsoinagree-mentwiththecitedobservationswherethegreatestchemicalheadlossfactors areassociatedwiththinnerbedsasdescribedintheresponsetoESGBRAIla.

AlthoughitislikelythatmeansrelatedtosmallerbreaksintheCASAGrande analysisshouldbelargerthanthemeanoftheLBLOCA,increasingthemeans forsmallerbreakswillnotincreaseriskbecausetheLBLOCAmeaninCASA Case01(allequipmentoperates)ishigherthantheexperimentalobservation andmostfailuresoccurforlargebreaks.Asensitivitystudyofsmaller-break meansindicatedthatameanof60forsmallerbreaksdoesnotincreaserisk.A meanof60forsmallerbreaksisamuchlargerchemicalheadlossfactorthan necessarytoadequatelyassessthemultiplicativeeonconventionalheadlossfromprecipitateloading[Enclosure1,Section4.1].ThisconservatismisTuesday1 stMarch,2016:19:32,Page259of393 DRAFTPART2.RAIRESPONSES(ROUND1)alsodemonstratedbythesensitivityanalysisdiscussedintheresponsetoESGBRAI5.Itisnotmoreprobablethatadebrisbedforsmallandmediumbreaks(com-paredtolargebreaks)wouldconsistprimarilyof"ber"nes.Inthehypothetical caseofbreaksthatoccurinsideofacontainmentbuildingthatistotally"lled withLDFG(uniform"berglasseverywhere),everybreakgeneratesthesamevol-umetricproportionof"nes,smallpieces,largepiecesandintactblankets(LAR Enclosure4-3,Reference[46],Table3.1.3).Then,onesetofdebris-sizedepen-denttransportfractionsisappliedforeverybreak(seedebristransportlogic diagramsinLAREnclosure4-3,Figure5.5.2-Figure5.5.4,Pages165-166).

Finally,oncedebrisarrivesatthepoolALL"nesandsmallpiecesareassumed totransport.Thus,thecompositionof"berarrivingatthestrainerisidentical forallbreaksizes,butthevolumesincreasewithincreasingbreaksize.Atthe strainer,allLDFGistreatedwiththepropertiesofindividual"bersforhead losscalculation,regardlessofitsoriginaldestructionsize.

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.5ESGB,ChemicalQuestion2 STPResponse:(Item2,Page54)Table1displaysthemaximumconventionalheadlossandthemaximumtotalheadloss(i.e.,aftertheadditionofchemicalprecipitates)foralltherelevant STPplant-speci"cstrainertestsconductedatARL.Table1alsodisplaysthe correspondingLBLOCAheadlosspercentilesforCASAGrandeCase01(all equipmentoperates).Table1:HeadLossTestMaximumandCorrespondingPercentileConventionalHeadLossTotalHeadLossTestedMaximumPercentileforTestedPercentileforTestCase01LBLOCAsMaximumCase01LBLOCAsTest3,Feb.

>15ft>100%n/an/aTest4,Feb.5.6ft99.96%8.8ft99.51%

Test5,Feb.4.8ft99.81%7.2ft99.34%

Test2,Jul.4.9ft99.83%9.1ft99.53%(Test1inFebruaryandJulywerecleanscreenheadlosstests.Test2inFebruarywasa"beronlytest.)EventhoughtheFebruaryheadlosstestsweresupersededbytheJulyheadlosstests,becausetheFebruarytestsusedwalnut"ourasaparticulatesurrogate (determinedtobenon-representativewithregardtowalnut"our),theCASA GrandeheadlosspopulationforCasaGrandeCase01boundedalltheresults exceptfortheconventionalheadlossofTest3inFebruary.Test3wasterminated afterlargeheadlosses,greaterthan15ft,wereobservedfollowingtheaddition of"ne"brousdebris(2);asalreadystated,thistestusedwalnut"ourasa particulatesurrogateandwassuperseded.AsexpectedtheDBAtestsoccurredTuesday1 stMarch,2016:19:32,Page260of393 DRAFTPART2.RAIRESPONSES(ROUND1)inthetailsofthedistribution.ThefollowingmaximaareforCASAGrandeCase01.Themaximumcon-ventionalCASAGrandeheadlosswas8.2ft.ThemaximumtotalCASAGrande headlosswas161.9ft.Fortheheadlosscomparisonscitedabove,theheadlosseswerenotcorrectedtoacommon"owrateandtemperature,whichisconservativeasstatedinthe responsetoESGB,SteamGeneratorTubeIntegrityandChemicalEngineering

-ChemicalRAI20inSTPlettertoNRCdatedJune25,2014,NOC-AE-14003101,ML14178A481andML14178A485).

References:

1.0415-0100067WN/0415-0200067WN.SouthTexasProjectTestPlanFeb2008.RevisionA.11/24/2008 2.0415-0100069WN/0415-0200069WN.SouthTexasProjectTestReportfor ECCSStrainerPerformanceTestingFeb2008.RevisionA.11/24/2008 3.0415-0100070WN/0415-0200070WN.SouthTexasProjectTestPlan.Re-visionA.8/14/2008.

4.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportfor ECCSStrainerTestingJuly2008.RevisionA.11/24/2008.2.3.5.6ESGB,ChemicalQuestion4STPResponse:(Item4,Page54)Asensitivitystudyrelatedtochemicalhead-lossfactortailprobabilitywasnotperformedconcurrentlywithconstantconventionalheadlossbecausethis assumptionwouldnotgeneratemeaningfulrisk-informedresultsthatcouldbe comparedtothebaseline.Baselineconventionalheadlossiscomputedasa functionofwatertemperature,whichcomplicatestherequestedcomparison.

However,astudywasperformedusingCASAGrandeCase01(allequipment operates)chemicalhead-lossfactorswithtailprobabilitiesrangingfrom1E-1to 0.1E-9toassesschangesinreferencedtothebasecase.AsshowninFigure 1,decreasingthetailprobabilityincreasestheratiowhileincreasingthe tailprobabilitydecreasestheratio.Itshouldbenotedthatbecausethe exponentialdistributionisasingle-parameterfunction,theconcurrentmaxima alsodecreasewithincreasingtailprobability.Allcasesexceptthe"rst(1E-1) wererunwiththesamenumberofstatisticalsamplestoillustratethatthe variancegrowsasexpectedwhenthesamesamplesarespreadoverawiderspan oftheparameter.2.3.5.7ESGB,ChemicalQuestion5 STPResponse:(Item5,Page54)TheCASAGrandemodelassessesheadlossfrompossiblechemicalsourcesbyapplyingadistributionofchemicalhead-lossfactorsasafunctionofbreak category(LAREnclosure4-3,Table5.6.4)asdescribedinLAREnclosure4-3, Section5.6.3.Expectedvalues(means)ofthechemicalhead-lossfactordistribu-tionsre"ectthemaximumobservedconventionalheadlossincreaseofadesign basisbed(LAREnclosure4-3,Reference[53])fromthecompleteadditionof aprecipitateloadgeneratedundertheassumptionsof30-day,continuoussprayTuesday1 stMarch,2016:19:32,Page261of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:SensitivityofCDFtochemicaltailprobabilityforCASAGrandeCase01.exposureofdeterministicallyboundingmaterials(LAREnclosure4-3,Reference[53],[1]).AlthoughthedistributionsarecorrelatedtoeachLOCAcategoryby virtueoftheirseparatelyde"nedmeans,magnitudesofthehead-lossare notdirectlylinkedtoestimatedmaterialreleaseforeachbreakconditionas-sessedbyCASAGrande;theconservativechemicalinventoryisassumedforall breakscenarios.Keyparametersthatmayin"uencethechemicalmodelperformanceare(1)useofthe140Ftemperaturecriterionforapplicationofthechemicalhead-lossfactor,(2)selectionofchemicalhead-lossfactormeanvalues,(3)distribution typeand(4)applicationofathin-bed"ltrationcriterion.Ofthefourkeypa-rameterslisted,thetypeofthestatisticsdistributionchosenforimplementation ofthechemicalhead-lossfactorsandtheapplicationofthethin-bed"ltration criteriondonotrisk.Exponentialdistributionswerechosenasasingle parameterdistributionwithashapecontrolledbythemeanandananalytic probabilityintegralforreportingmaximarelatedtoa"xedtailprobability.

Manychoicesoftruncateddistributionscouldbeusedwithequaletopre-servedesiredstatistics.Sensitivityanalysisofthethinbedcriterionresultedin aratioofoneasshownbyFigure1forcontributionsfromsump-strainerfailures computedwhenthethinbedcriterionwasremoveddividedbycontributions fromsump-strainerfailurescomputedforthebaseline,indicatinganulleof thethinbedcriteriononrisk.ToevaluatetheeoftheremainingkeyparametersonCASAGranderesults,sensitivitystudieswereperformed.Thatshowednosensitivitytothe temperaturethreshold.Thesesensitivitycaseswererunwiththefollowingas-sumptions:(1)withthe140Ftemperaturethresholdapplied(bluedots),and(2)withoutatemperaturethresholdapplied(greendots).Allcalculationsshown heredoapplythethin-bedcriterionforapplicationofthechemicalhead-lossfac-

tors.Clearly,sometreatmentofchemicalhead-lossisessentialtoevaluatingriskTuesday1 stMarch,2016:19:32,Page262of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:Riskresultingfromthin-bedcriterion.ThickBed0indicatesthethinbedcriterionwasremoved.Figure2:Summaryofchemicalhead-losskeyparameterssensitivityanalysisandriskasshowninFigure2bycaseBump-UpNotApplied,becausenofailuresinthesumpwerepredictedtooccurbasedonconventionalheadlossalone.Useofthe140Ftemperaturecriterionforapplicationofthechemicalhead-lossfactordoesnotsigni"cantlyanyofthesensitivityresultsortheriskcalculated byCASAGrande(seeESGBRAI8response).Applicationofconstanthead-lossfactorsequaltothecurrentformalmeansoftheexponentialdistributionslowerstheriskforthecaseAllConstantlx FormalMean".However,applicationofconstantmultipliers(2Xand3X)onthe formalmeanincreasestheriskasshownbycasesAllConstant2XFormalMeanTuesday1 stMarch,2016:19:32,Page263of393 DRAFTPART2.RAIRESPONSES(ROUND1)and"AllConstant3XFormalMean.Useofaconstanthead-lossfactorequaltothemeanappliestheexperimentally-observed,worstcase(or2Xto3Xthe worstcase)chemicalheadlossmultiplicativeresponseforallbreaks.Useofotherdistributions,whilepreservingthesameinterpretationofdata,willresultinnearlyidenticalriskresults.However,toshowtheeofal-ternativeprobabilitydistributions,riskratioswereassessedwithatruncated normaldistributionforeachscenario(betweenIandthepresentmaxima)with astandarddeviationofthreetimestheindividualscenariomeanshownascase "Normal(Mean,3XMean)"inFigure2.Althoughtheindividualscenariomeans oftheanalysiswerepreservedinthisdistribution,thelargestandarddeviation approximatesauniformdistributionoverthecompleterange,thus,changingthe intendeduseofthedataandproducinganon-comparativeresult.oftheexponentialdistributionmeanvalueswerealsoevaluatedinthissensitivityanalysisusingareversecorrelationofincreasingchemicalhead-lossfactorwithdecreasingbreaksize.Case"Expo(6,3.5,2.25)"assignedthe SBLOCAmeanto6,theMBLOCAmeanto3.5andtheLBLOCAto2.25.

ThisreversecorrelationpreservestheSTPexperimentallyobservedmultiplica-tivechemicalhead-lossresponseoftheLBLOCA(LAREnclosure4-3,Reference

[53])andincreasestheothermeansasafunctionofdecreasingbreaksize.This reversecorrelationre"ectstheobservedthin-bedwherethemultiplica-tiveresponseofprecipitateloadingonsmallerbreakdebrisbedsisgreaterthan thatobservedfromthesameprecipitateloadingonlargebreakdebrisbeds

[Enclosure1,Section4.1].Althoughthemeanswerelargerforsmallerbreaksas comparedtothemeanofthelargebreak,riskdecreasesbecausetheconservatism associatedwiththeLBLOCAmeanwasdecreasedandbecausetheincreasein meansassociatedwiththeSBLOCAandMBLOCAbreakswerenotst toinducefailure.Afurthersensitivitystudyindicatesthatthemultiplieronthe MBLOCAconditionmustbehigherthan60toincreasetheriskassignedby CASAGrandeCase01(allequipmentoperates).TheSBLOCAheadlossfactor inthissensitivity,althoughhigherthanassumedintheLAR,doesnotin"uence theriskbecausenoneoftheSBLOCAscenariosformathinbed.

References:

1.Westinghouse,"SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,"WestinghouseElectricCompany,December2006.2.3.5.8ESGB,ChemicalQuestion6 STPResponse:(Item6,Page54)TheCASAGrandetreatmentofchemicaldoesnotdistinguishtherel-ativecontributionsfromsprayedmaterialsandsubmergedmaterials.ThePDF meanvaluesofthechemicalhead-lossfactorsusedintheCASAGrandeanal-ysis(LAREnclosure4-3,Section5.6.3)toinduceamultiplicativeincreasein conventionalheadlossarebasedonSTPtestingofaworst-caseprecipitateload acrossadesignbasisbed[1].Theworst-caseprecipitateloadwasgeneratedas-suming30-daysofsprayoperation[2,Table6.3-7],[1,Page54].WhiletheCASA Grandeanalysisassumesthatallspraysaresecuredatapproximately6.5hours withrespecttostrainer"owrate,thechemicalhead-lossfactorsre"ectchemical headlossattributableto30daysofcontinuoussprayonallexposedsurfacesand 30-daysofcorrosionforallsubmergedmaterials.Tuesday1 stMarch,2016:19:32,Page264of393 DRAFTPART2.RAIRESPONSES(ROUND1)Giventheassumed30-dayinventoryofchemicalproducts,spraytimingas-sumedinCASAGrandedoesnotthechemicalsourcetermortheprob-abilityofprecipitation,sonosensitivitieswereperformedonthespraytimeto addressthisRAI.

References:

1.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting(66-9088089-000),August2008.2.Westinghouse,SouthTexasProjectGSI-191 ChemistryEvaluationCN-CSA-06-6,WestinghouseElectricCompany, December2006.2.3.5.9ESGB,ChemicalQuestion8 STPResponse:(Item8,Page55)TheCASAGrandemodeldoesnotexplicitlyincludecalciumsourcessuchasconcretedust,concreteablatedbythejet,andotherplantmaterialssuch asinsulation,butrather,appliesaseparatechemicalhead-lossfactorforeach LOCAcategorytoincreaseheadlossforallanticipatedchemicalproducts.The head-lossfactormeansarebasedonthemaximumheadlossobservedduring STPECCSstrainertestingofa30-dayworst-caseprecipitate(includingboth calciumandaluminum)load(LAREnclosure4-3,Reference[53],[1])acrossa designbasisbed.Somepipebreaksmayproduceenoughcalciumtoformprecipitatesinthesumppoolpriortobulk"uidtemperaturesreaching140F(approximately17.8hrforSBLOCAandMBLOCA,5.0hrforLBLOCA).Insuchcases,calcium leachingratesmaybettoexceedcalciumphosphatesolubilityatpool temperaturesandpHvalueswithinthesetimeperiods.Ahighertemperaturethresholdthatpermitsimmediatechemicalhead-lossforCASAGrandeCase01(allequipmentoperates)increasesthetotal riskbyapproximately4%.Alloftheadditionalscenariofailuresareattributed tohigherchemicalinducedheadlossatthestrainer.Coredebrisaccumulation doesnotdependonthechemicalhead-lossfactors.Analternativechemically-inducedhead-losscalculationdescribedinSection4.5ofEnclosure1thatisadditiveandincorporatesboththetypeofprecipitate andthedebrisbedareatoquantifytotalheadloss,alsoshowsthatpossible precipitateformationpriorto140Fwouldinducelittleincreaseintotalhead loss.

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.10ESGB,ChemicalQuestion9 STPResponse:(Item9,Page55)Althoughchemicalhavenotbeenfoundtobesigni"cantcontribu-torsinSTPpost-LOCAsumpconditions,CASAGrandeincludesuncertainty forchemicalcontributiontoheadlossasarandomvariablemultiplierwitha meangreaterthan1.Assuch,nomodelsofdissolutionorsolubilitylimitsap-peardirectlyintheCASAGrandeanalysis,souncertaintiesassociatedwith adissolutionmodelandsolubilitylimitswerenotexaminedexplicitly.Expo-nentialprobabilitydensityfunctions(PDFs)de"nedforthechemicalhead-lossTuesday1 stMarch,2016:19:32,Page265of393 DRAFTPART2.RAIRESPONSES(ROUND1)factorsdescribethemagnitudeofthehead-lossthatwillbeobservedafterchemicalproductsform.Themagnitudeofhead-lossisindependentof dissolutionprocessesandsolubilitylimits,sotheseconsiderationsarenotfac-toredintothePDFsde"nedforchemicalbump-upfactors.Asdescribedinthe responsetoESGBRAI1c,thechemicalhead-lossfactormeansre"ectthemaxi-mumobservedconventionalheadlossincreaseofadesignbasisbed[1]fromthe completeadditionofaprecipitateloadgeneratedunder30-day,continuousspray exposureofdeterministicallyboundingmaterials(1,2]andthesingle-parameter exponentialPDFwaschosenforshapeandforconvenienceof"ttingthedesired statisticsofthemeanandatruncatedtailprobability.However,thecriterionof

140+/-5Fforimplementationofthebump-upapproachwaslooselyderivedfromindustrypracticefordelayedonsetofprecipitationbasedonaluminumsolubil-ity[3,4]anddoesacknowledgethatprecipitationtemperaturedependsonthe productsinquestionandonthechemicalenvironment.Applicationoftheprecipitationtemperatureistheonlyconsiderationofsol-ubilitypresentintheSTPLARanalysis.AsdescribedintheresponsetoESGB RAI10,acceptabilityofthe140

+/-5FtemperaturecriterionwasexaminedasafunctionofuncertaintyintheexpectedrangeofSTPpost-LOCApH,pool temperature,andvariableinventoryofmaterialexposure(LAREnclosure4-3, Reference[201).WhileLAREnclosure4-3,Reference[20]concludedthatalu-minumprecipitationwasunlikelytooccurwithintheparameterrangesexamined priorto140

+/-5F,thereferencedidnotexaminepotentialofotheruncertain-tiesrelatedtomaterialreleaserates,chemicalmodeling(thermodynamicand kinetic)calculationsusedtoassesssolubility(equilibriumcoets,enthalpy, speci"edreactions,andtime)andcalciumprecipitationpriorto140

+/-F.Sincealluncertaintiesassociatedwiththecriterionof140

+/-5Fthatwaslooselybasedonaluminumsolubilitywerenotfullyaddressed,thepossiblein-creaseinriskthatcouldoccurthroughtheuseofahighertemperaturecriterion wasexaminedasasensitivitycase.Useofahighertemperaturethresholdthat permitsimmediateapplicationofthechemicalhead-lossfactorsincreasesthe riskofCASAGrandeCase01(allequipmentoperates)byapproximately4%as discussedintheresponsetoESGBRAI8.Thisincreaseisnotlikelytoposea practicalconcern.

References:

1.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting(66-9088089-000),August2008.2.Westinghouse,SouthTexasProjectGSI-191ChemistryEvaluation CN-CSA-06-6,WestinghouseElectricCompany,December2006.

3.AluminumSolubilityinBoronContainingSolutionasaFunctionofpHand Temperature,Adams#ML091610696,September2008.

4.Entergy,GL2004-02FinalSupplementalResponsesAdams#ML082700499,

2008.2.3.5.11ESGB,ChemicalQuestion10 STPResponse:(Item10,Page55)Poolchemistry,poolpHandtheamountsofaluminumandcalciumwereconsideredintheadoptionofthechemicalprecipitationthresholdtemperature andinthede"nitionofthechemicalhead-lossfactors.However,thesefactorsdoTuesday1 stMarch,2016:19:32,Page266of393 DRAFTPART2.RAIRESPONSES(ROUND1)notappearexplicitlyinCASAGrandeinput.TheconditionsusedtocontrolapplicationofchemicalbumpupapproachintheCASAGrandeanalysisareatemperatureof140

+/-5Fwhena"berbedgreaterthanorequalto1/16forms,asindicatedinLAREnclosure4-3.The choiceof140

+/-5Fasachemicalprecipitationtemperatureisnominallybasedonindustrypracticefordelayedonsetofaluminumprecipitation[1,2],onreview ofCHLEtanktestresults(LAREnclosure4-3,Reference[18,19])andoneval-uationofmultipleWCAP-16530-NPprecipitatereleasecalculationsunderSTP post-loss-of-coolantaccident(LOCA)scenarios(LAREnclosure4-3,Reference

[20]).MultipleWCAP-16530-NPcalculationswereperformedtocon"rmthatthe precipitationonsettemperatureadequatelyassessesuncertaintyrelatedtopH, poolchemistryandmaterialexposurethatprecipitategeneration(LAR Enclosure4-3,Reference[20],Tables1-3).TheWCAP-16530-NPcalculations showthatthelikelihoodofaluminumprecipitationabovethetemperatureof

140+/-5FwithvariablepoolpH,poolchemistryandvariablematerialinvento-riesislow(LAREnclosure4-3,Reference[20],Table4).TheWCAP-16530-NP calculationsofLAREnclosure4-3,Reference[20]didnotexplorespraydurations longerthan6.5hoursanddidnotaccountforzincrelease.However,chemical head-lossfactordistributionswerebasedonconservativechemicalproductin-ventoriesasdescribedbelow.Exponentialprobabilitydensityfunction(PDF)meanvaluesappliedaschem-icalhead-lossfactorsprovideaconservativelylargechemicalheadlossresponse thataccountsforexclusionofzinc-relatedchemicalandboundsthereal-isticevaluationof6.5hoursofsprayexposure.Conservatismisensuredbecause themeanheadlossvalues(LAREnclosure4-3,Table5.6.4)re"ectthemul-tiplicativeincreaseofconventionalheadlosscausedbyaworstcasechemical precipitatetestloadappliedtoadesign-basisdebrisbed(LAREnclosure4-3, Reference[53],[3]).Thisworstcaseprecipitateloadcorrespondsto30-dayspray exposureofdeterministicallyboundingaluminum,siliconandcalciumbearing materialquantities[3].Theexperimentallyobservedmultiplierof2.25wasas-signedtosmallbreaksandthenincreasedforlargerbreaks.Also,theexpected STP-post-LOCAmaterialreleasesdeterminedbycalculationslistedinLAREn-closure4-3,Reference[20]aremuchlessthanthe30-daychemicalinventoryused instrainertesting(LAREnclosure4-3,Reference[53],[3,Table6.3-7]).Chem-icalhead-lossfactorsbasedonaboundingchemicalheadlossresponse aredependentonbreaksizeregardlessofrealisticspraydurationandmateri-alsexposed,whichfurtherenforcestheconservativeinterpretationofthemean values.

References:

1.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,andNatesan,K.AluminumSol-ubilityinBoronContainingSolutionsandaFunctionofpHandTemperature, ADAMS#ML091610696,ArgonneNationalLaboratory,September,2008.

2.Entergy,GL2004-02FinalSupplementalResponses,Adams#ML082700499, September2008.

3.Westinghouse,SouthTexasProjectGSI-191ChemistryEvaluation CN-CSA-06-6,WestinghouseElectricCompany,December2006.Tuesday1 stMarch,2016:19:32,Page267of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.5.12ESGB,ChemicalQuestion14aSTPResponse:(Item14a,Page57)Uncertaintiesfromradiationonprecipitateformationwerenotexam-inedbecausein-situcorrosionanddissolutionprecipitateswerenotobservedin prototypicaltestsolutions(LAREnclosure4-3,Reference[18,19]).2.3.5.13ESGB,ChemicalQuestion14b STPResponse:(Item14b,Page57)Uncertaintiesfromradiationondebrisbeddegradationwerenotex-aminedbecauseTriNuclearpolyesterand"berglass"ltercartridgesusedbySTP haveaspeci"edmaximumaccumulateddoseof106radstoavoid"lterdegra-dation[1,2].These"ltersareusedinthespentfuelpoolandcoretoremove particulatesandmaintainwaterpurityspeci"cations.Itwasinitiallyassumed thatthedoselimitwasrecommendedtoavoiddegradationof"berglass,when infact,itisrecommendedtoavoiddegradationinmodelsthatcontainpolyester (hydrocarbon)"ltermediathatismoresusceptibletoradiationdamagethan glass.Thefollowingorder-of-magnitudeargumentdemonstratesitisunlikely that"berglassdebrisreceivesadosegreaterthan106radsfromcruddeposition

alone.Thespeci"cactivityofcrudpresentatSTPisunknown,buthealthphysicssurveysofspent"ltersthatcollectcrudarecommonpractice.Itisimportantto notethatCo-58andC0-60,signi"cantdosecontributorsfromcrud,arehighly solubleintheRCSsolutionandarenotcapturedinthe"lters.Similarly,these isotopeswouldnotremainresidentinthedebrisbed.Crudconstituentsolubility doesnottheaccuracyofthisanalysis,butitisanimportantconsideration beforeadoptingcrudactivityvaluesreportedintheliterature.Themassofcrudcollectedin"lterscanberelatedtothethresholdof106radtojudgewhether"berglassdebriscanreceiveahigherdose.Itisassumedthat thephysicalformofcrudcapturedinthebedisidenticaltotheformcaptured inthe"lters.Thedoseto"berglassdebriscanbeapproximatedas D bed=Mcrud bedA)crudbed T bed Mfiber bed (A)where: Mfiber bed=massof"berglassinthedebrisbed Mcrud bed=massofcrudinthedebrisbedA)crud=energyreleaserateperunitmassforspeci"cactivity A andaveragegammaenergybed=eeabsorptioninthe"bermat T bed=bedexposuretimeThedoseratemeasuredbyahealthphysicssurveymetercanbeapproxi-matedasDfit=McrudfiltA)cruddetect M detect (B)where: Mcrudfilt=massofcrudinthe"lterTuesday1 stMarch,2016:19:32,Page268of393 DRAFTPART2.RAIRESPONSES(ROUND1)A)crud=energyreleaserateperunitmassforspeci"cactivity A andaveragegammaenergydetect=eecaptureofthesurveymeter M detect=eemassofthedetectorSolvingEquationAandBforthecommonenergyreleaserateperunitmassA)crudandisolatingcrudmassinthe"ltergives Mcrudfilt=Dfit Mcrud bedbed T bed M detect D beddetect Mfiber bed(EquationA)NumericparametersusedtoevaluateEquationCareshowninTable1.AconstantmaximumcrudinventoryisassumedintheSTPLARanalysis, butthedebrisquantitycanvary.Concentratingtheassociatedenergyrelease inminimumdebrismassrepresentsamaximumexposuretoradiation,soa 1/16-in.equivalentthinbedwasassessedforcomparisonpurposes.Assuming lowbedcompactionequaltothemanufactureddensityfurtherconcentrates theradiationdose.Relativelythinporousmediaarenotwellcoupledtothe particulateradiationsourcefortgammaenergyabsorption,soanee absorptionfractionof0.1wasassigned.Similarly,ahand-heldgammasurvey meterhaspoorcollectionfora30-in.long,6-in.diameterstainlesssteel "ltercartridgecontaininganannular,cylindricalradiationsource,soavalueof 0.15wasassigned.Table1:Parametersfor"berglassdoseassessment.bedpackingdensity2.4lbm/ft3maxdose106rad(J/kg) bedabsorbfract0.1 bedthick1/16thin onestrainerarea1818.5ft2

1. strainers3 debrisexposuretime30days crudmassinbed24lbm edetectormass100g detector0.15 max"lterdoserate20rad/hrUndertheassumptionslistedinTable1,themassof"berglassdistributedonall3strainersisapproximately31kgandthecrudmassestimatedtobeon the"lterislessthan1gram.Forcrudburstcleaningprocedurestobee relativetothe24Ibmmaximuminventory,"ltersmustcollectupto1-pound quantities.Therefore,itisnotlikelythat"berglassinthedebrisbedcanreceive adosefromaccumulatedcrudthatmeetsorexceeds10 6rad.Apredicted"ltermassof1pound(450g)correspondstoadebris-beddoseofonly750rad.

RCS"ltersatSTParenotcommonlyweighedformassincrease,soquantitative con"rmationoftheseobservationsisnotavailable.

References:

1.TriNuclearCorp.UnderwaterFilter/VacuumUnitsAssembly&Operat-ingInstructions.December2012.Tuesday1 stMarch,2016:19:32,Page269of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.TriNuclearCorp.TNC-019-02standard"lterdrawingandproductde-scription.2.3.5.14ESGB,ChemicalQuestion14c STPResponse:(Item14c,Page57)Uncertaintiesfromchemicalsleachedfromunquali"edcoatingsatSTPwerenotconsideredexplicitlyintheassessmentofpotentialchemicalHowever, exponentialdistributionsofchemicalhead-lossfactorsappliedintheanalysisdo permitchemicalhead-lossethatexceedlevelsthatareexpectedfrom30-dayinventoriesofaluminumandcalciumcompounds.Someofthismargincanbe interpretedasvariabilityintroducedbyanychemicalsleachedfromunquali"ed coatings.Thephenomenaofunquali"edcoatingsdegradationintoagelatinous debrissourcewasnotconsideredinthechemicalanalysisthatsupported theSTPCASAGrandeevaluation.Itisgenerallyassumed(LAREnclosure 5,Reference[3])thatunquali"edcoatingsfailintoconstituentsolidswithout furthercontributiontothechemicalenvironment.CoatingstestedinLAREnclosure5,Reference[3]areassumedtobesimilartothosedocumentedinSTPunquali"edcoatingsdocumentation(LAREnclo-sure4-3,Reference[12]).However,sincedetailedproductinformationassociated witheachtypeofcoatingwasnotavailable,onlygeneralcomparisonsweremade betweencoatingcategoriesofthoseatSTPandthoselistedinLAREnclosure 5,Reference[3].2.3.5.15ESGB,ChemicalQuestion15 STPResponse:(Item15,Page57)TheCASAGrandemodeldoesnotdetermineachemicalsourcetermfortbreaksizes,anditdoesnotassesssmallerbreakconditionsthatmay thecalciumandaluminumconcentrationswithintheanalysis.Rather,the CASAGrandemodelassessesheadlossfrompossiblechemicalsourcesbyapply-ingarangeofchemicalhead-lossfactorsasafunctionofbreakcategory(LAR Enclosure4-3,Table5.6.4)thataccountforchemically-inducedheadloss(LAR Enclosure4-3,Section5.6.3).Therangesofappliedchemicalhead-lossfactors arebasedonstrainertestingconductedusingadesign-basisdebrisbedasde-scribedbelow,adequatelyboundchemicallyinducedheadlossfromaspectrum ofchemicalsourceterms.Deterministicanalysesalsodonottypicallyconsider howasmallerbutpotentiallymorefocusedjetmaythecalciumandalu-minumconcentrations.Thechemicalhead-lossfactorsrangefromrepresentativetohighlyconserva-tivemultipliersandareusedinbreak-speci"cexponentialprobabilitydistribu-tionsthatwereadaptedforusewiththechemicalbumpupapproachdescribed inLAREncl.4-3,Section5.6.3.AsdescribedintheresponsetoESGBRAI1c, themostprobablehead-lossfactors,basedonexperimentalobservation(LAR Enclosure4-3,Reference[18,19]),correspondtothemodeof1.0(one)forall breaks.Thechemicalhead-lossfactormeansre"ectthemaximumobservedcon-ventionalheadlossincreaseofadesignbasisbed[1]fromthecompleteaddition ofaprecipitateloadgeneratedunder30-dayandcontinuoussprayexposureof deterministicallyboundingmaterials(LAREnclosure4-3,Reference[531,[1]).

ThemaximaoftheexponentialPDFswerecon"rmedtobevaluescapableofTuesday1 stMarch,2016:19:32,Page270of393 DRAFTPART2.RAIRESPONSES(ROUND1)producingaquanti"ablenumberofchemicallyinducedfailuresincombinationwiththespectrumofconventionalheadlossexperiencedwithineachbreaksize andwereatleast6.8timeslarger,thanthemeanfactorofagivenbreaksize PDF.Theexponentialdistributionswerenotadjustedforlowerchemicalinven-toriesthatmightbeevolvedduringshorteraccidentperiodsorfortheabsence ofspraysinsmallbreakscenarios.

Reference:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.16ESGB,ChemicalQuestion16 STPResponse:(Item16,Page57)Yes,Tables2.5.34and2.5.35inVolume6.2summarizetheresultsofthe30-dayreleasedmaterialconcentrationsandtheevaluationofprecipitateoccurrence underspeci"edconditions(LAREnclosure4-3,Reference[20],Table4and5).

ThepHpro"lesusedinthesimulationssupportingthetableswerealinear responseinTSPdissolutiontimethatstartedatapHof4.5androsetothe steady-stateminimum(pH7.0)ormaximum(pH7.3)over80minutes(LAR Enclosure4-3,Reference[20]).ThesteadystatepHwasdeterminedfromthe rangeofTSPmasswithincontainment[2]andthebestestimatewatermass forLBLOCA(LAREnclosure4-3,Reference[14],Table6.2).Theminimum andmaximum"berquantitiesandwatervolumeforeachbreaksizethatwere usedforWCAP-16530-NP-Acalculationsandtheassumedplantconditionis displayedinTable1(LAREnclosure4-3,Reference[20],Table1).Theamountof LDFGwasdeterminedfromtheCase01(allequipmentoperates)CASAGrande simulation.PlantconditionsforwatervolumesweredeterminedfromSTPPost-LOCAWaterVolumeAnalysisat130F(LAREnclosure4-3,Reference[14],Table5.9).Table1:WCAP-16530-NP-AInputandPlantConditionComparisonMinLDFG(ft3)MaxLDFG(ft3)MinWaterVol.(ft3)MaxWaterVol.(ft3)WCAPPlantCon-ditionsWCAPPlantCon-ditionsWCAPPlantCon-ditionsWCAPPlantCon-ditionsSBLOCA001012.862,70063,31475,92176,665 MBLOCA1006010966,41167,06279,63280,412 LBLOCA600.72,3852421.466,41167,06279,63280,412Withtheexceptionofthemaximum"berglassquantityforMBLOCAsce-narios,theboundsoftheanalysiswouldnotbesigni"cantlylargerthanthose examined.TheunderestimatedMBLOCAmaximum"berglassquantitymayun-derestimatesimulatedcalciumandaluminumreleaseforMBLOCAcases.An-otherslightdnotaccountedforinthesimulationisassociatedwiththe pH.Completedissolutionwasassumedtooccurwithin80minutes,but thepHpro"leforeachbreaksizemaybeslightlytbecauseofvariable RWSTdraintime.However,onlythe1.5-inchbreak(LAREnclosure4-3,Page 1-10)takeslongerthan80minutestodrain.Therefore,mostbreakswillreach thesteadyboundssoonerthanindicatedbytheanalysis.Also,the"nalsteady statepHboundswerebasedonLBLOCAbestestimatewatermass,the"nal steadystatepHboundsforaMBLOCAarecorrectlyassessedsincethebestes-Tuesday1 stMarch,2016:19:32,Page271of393 DRAFTPART2.RAIRESPONSES(ROUND1)timatewatermassforaMBLOCAandLBLOCAarethesame((LAREnclosure4-3,Reference[14],Table6.2).However,therewouldbeapproximately11%less solutioninaSBLOCAthaninaLBLOCAscenario.Thisfactsuggeststhatthe pHrangeexaminedmayhavebeenslightlyunderestimatedinthesimulationof smallbreaks.ThereforethepHrangeofaLOCAeventcouldbeslightlylarger thanthe0.3pHunitspredicted.ThepHrangemayhavebeenslightlyunderestimatedinthesimulationofSBLOCA,duetohavingabout11%lesssolutioncomparedtoLBLOCAsce-narios.BecauseSBLOCAsdonotchallengeGSI-191successcriteria,andthe 11%decreaseinpoolsolutiononlyresultsina5%relativeincreaseinTSP concentration,thepH(andpHrange)isvalidandencompassesallscenariosof

concern.2.3.5.17ESGB,ChemicalQuestion18a STPResponse:(Item18a,Page58)ThesupplementaryinformationprovidedbyVolume6.2,"Item5.a.6:corro-sionanddissolutionModel,"onlyprovidesgeneralizedinformationandwasnot directlyappliedintheCASAGrandeanalysis.Thesjudgmentthatallowssubstitutingaluminumoxyhydroxideforsodiumaluminumsilicateisnotrelevanttosolubilitywhenevaluatingtheforma-tionofanaluminumbasedprecipitateinpost-LOCA"uidscontainingdissolved aluminum.Thetextdidnotconveytheintendedconceptthattheuseofalu-minumoxyhydroxidesolubilitytopredicttheformationofsodiumaluminumsil-icatewasassumedtobeadequateforageneralassessmentofaluminumproduct formationoraluminumsolubilitysincesolubilitylimitsofthesetwocompounds wereshowntobesimilar(i,Section6,items6and7).2.3.5.18ESGB,ChemicalQuestion18b STPResponse:(Item18b,Page58)LAREnclosure4-3,Reference[20]referencedanaluminumsolubilitydeter-minedfromtheuseofVisuaIMINTEQv3.0withSTPspeci"csolutionchem-istryatapHof7.0andtemperatureof140OF.Usingasolubilityof2.7mg/L obtainedfromANLsequationwouldincreasethelikelihoodofaluminumpre-cipitationunderconditionsexaminedbyLAREnclosure4-3,Reference[20]and wouldhavelikelyresultedinahighertemperaturecriterionforonsetofprecip-itationintheCASAGrandeanalysis.However,asdiscussedintheresponseto ESGBRAI8,theuseofahighertemperaturethreshold(orimmediateimple-mentationofthemultiplicativeheadlossfactors)doesnotsigni"cantly riskassociatedwithCASAGrandeCase01(allequipmentoperates).2.3.5.19ESGB,ChemicalQuestion18c STPResponse:(Item18c,Page58)Figure2.5.34captionwasmislabeled.The"guredoesreferencecalciumphos-phatesolubility(LogKof-28.25andH rxnof-87kJ/mol)at185FrangingfrompH7.0to7.30.

Reference:

1.Westinghouse,WCAP-16785-NP,Rev0EvaluationofAdditionalInputstotheWCAP-16530-NPChemicalModel,WestinghouseElectricCompany,MayTuesday1 stMarch,2016:19:32,Page272of393 DRAFTPART2.RAIRESPONSES(ROUND1) 2007.2.3.5.20ESGB,ChemicalQuestion21 STPResponse:(Item21,Page59)AsstatedinSection2.2.11,thequantityofcrudassumedintheanalysisis24Ibm(LAREnclosure4-3,Reference[13]).WithinCASAGrande,crud isconsideredtobea15-

µmparticulate"newitha100%transportfractionunderallLOCAscenarios.Thefullcrudinventoryisintroducedduringthe"rst timestepofeachscenario,andcrudtransportstothestrainersinproportion totheirvolumetric"ow.Uponarrivalatastrainer,crudishomogenizedwith allotherparticulatesand"bertoformcompositedebrispropertiesthatare enteredinthehead-losscorrelation.STPdoesnotquantifytheamountofcrud releasedduringthecrudburstevolution.Theobjectiveofthecrudburstisto minimizeradiationworkerdose.Theenessofthecrudburstevolutionis measuredbydosecomparedtopreviousevolutions.Unlikeamomentum-driven processthatmaydislodgecrudfromRCSsurfaces,hydrogenperoxideisusedin achemicalprocesstomaximizeremovalofcrud.Anestimateofcrudquantity availableinanoperatingcycleismadeforthepurposeofcoredesignusing theEPRIBOA3.1software[1]toevaluatetheimpactofcrudinducedpower shift.BOAestimatesthecruddepositonthefuelandsteamgenerators.7STP BOAestimatesshowthattheSTPUnit1predictedinventoriesarelessthanthe industrynominal,sothe24Ibmcrudassumed(LAREnclosure4-3,Reference

[13])inCASAGrandeisappropriateandconservative.

Reference:

1.Boron-inducedAnomaly(BOA)RiskAssessmentTool:Version2.0.EPRI,PaloAlto,CA,1014961,December2007.2.3.5.21ESGB,Coatings:Question1 STPResponse:(Item1,Page59)Theunquali"edcoatingssizedistributionofTable2.2.18(LAREnclosure4-3)wastakenfromLAREnclosure4-3,Reference[12],Table7,Page32.This calculationreferencestheepoxysizedistributionsfrompaintchipcharacteri-zationofDBAcoatingstestingdocumentTXUPaintChipCharacterization, (1).AutoclavetestingwasconductedonTXU(ComanchePeak)suppliedcoat-ingsamplestodeterminesizedistributioncharacteristicsofunquali"edcoatings debris,measuredbyfailedmass,failedcharacteristicsize,andqualitativefailed shape(2).ResultsoftheTXUPaintChipCharacterization(1)document includedmasspercentagesforeachofthesize/qualitativeshapecategoriesof epoxy.Thesefailedmasspercentagesandsize/qualitativeshapecategoriesare representativeoftotalfailedinventoryfromtheundocumented(assumedun-quali"edcoated)autoclavetestedsamples.Theresultsofthetestwereapplied toestimatethesizedistributionoffailedepoxyforagivenvolumeofunquali"ed

coatings.

References:

1.ALION-REP-LAB-TXU-4474-02.TXUPaintChipCharacterization.Re-vision0:October2007.2.Keeler&LongPPGReportNo.06-0413,DesignBasisAccidentTestingofCoatingSamplesfromUnit1ContainmentTXUComanchePeakSES,AprilTuesday1 stMarch,2016:19:32,Page273of393 DRAFTPART2.RAIRESPONSES(ROUND1) 2006.2.3.5.22ESGB,Coatings:Question2 STPResponse:(Item2,Page59)AZOIwascreatedforeachofthefourdtbreaksizesinthreeboundinglocationswhichdeterminearealisticmaximumamountofsurfaceareaforthe tepoxy,polyamideprimer,andIOZcoatings.Duetothetinner diametersofpipes,the4DZOIradiusisusedfortheepoxyandinorganiczinc (IOZ)quali"edcoatingsassuggestedbyWCAP-16568-P.2.3.5.23ESGB,Coatings:Question3 STPResponse:(Item3,Page60)ThefailurefractiondistributionsgiveninLAREncl.5(Pgs.12-17)displaytheresultsofunquali"edcoatingsfailureanalysis(LAREncl.4-3,Ref.[12]),

andshowthatunquali"edcoatings(investigatedintheSTPevaluation)have probablefailurefractionranges.Thisfailurefractionanalysisisusefulbecause itshowsthatfailurefractionsotherthan100%areprobableforunquali"ed

coatings.However,thefailurefractionanalysisisnotusedintheCASAGrandeeval-uation.Allunquali"edcoatingsfailurefractionswere(assumed)setto100%.2.3.5.24ESGB,Coatings:Question4 STPResponse:(Item4,Page60)Yes.Forunquali"edcoatingsnotlocatedintheuppercontainment,100%ofthecoatingsareassumedtofailandareassigneda100%failurefractioninthe CASAGrandeinputdeck.Theamountofunquali"edcoatings(notinuppercontainment)availablefortransportis100%.However,thefailedunquali"edcoatings(notinupper containment)aresubjecttorecirculationtransportfractionsthatdesignatethe fraction(ofunquali"edcoatings)trappedassedimentandthefractionthat activelyrecirculatesinthecontainmentpool.Yes.100%ofthecoatingsthatarecalculatedtotransporttothestrainerareassumedtoarriveatthestrainer.Theunquali"edcoatingsquantitiescalculated totransporttothestrainerarethequantitiesthathavealreadybeenreducedor multipliedbythefailure(100%)andtransportfractions(location,recirculation).CASAGrandeintendedthatthemassofunquali"edcoatingsdesignatedasactivelyrecirculatinginthepoolbeaddedtothepoolatuniformrateover36 hours;however,acodelevelerror(CASAGrandev1.6ReleaseNotes,Error Report#04)forcedtheassumptionthatallactivelyrecirculatingmaterials, includingunquali"edcoatings,arriveinthepoolwithinthe"rst10minutesfor allscenarios.Additionalinformation ItshouldbeunderstoodthataccumulationofsuspendeddebrisdoesnotbeginuntilECCSrecirculationbegins.Afurtherclari"cationtothequestion statementisthatuniformdebrisadditiontothepoolataconstantrateisnot thesameasauniformarrivalrateonthestrainer.Therateofaccumulationon thestrainerisdrivenbytotalrecirculation"owrate,whichmaychangewith

time.Tuesday1 stMarch,2016:19:32,Page274of393 DRAFTPART2.RAIRESPONSES(ROUND1)Unquali"edcoatingsfailurefractions/percentagesdiscussedinLAREncl.5arebasedonanalysisofElectricPowerResearchInstitute(EPRI)data(1) performedinLAREncl.4-3,Ref.12(p.1-1).TheEPRIunquali"edcoatings study(i.,pp.4-5)reportsthepercentageofcoatingdetachmentfromsubstrates ofmultipleplant-providedsamplesfortcoatingtypes(e.g.epoxy,alkyd, etc.)subjecttodesignbasispreparation(radiationexposure),andautoclave conditions(temperature,pressure,andspray).TheEPRIdetachmentdatawas usedasthebasisforthefailurefractionsdescribedinLAREncl.5(p.11).CASA GrandedidnotusethesefailurefractionsfortheSTPanalysisdescribedinLAR Encl.43,intheirplace,100%failurewasassignedforallunquali"edcoatings.Theunquali"edcoatingsfailuretimingwascalculatedfromtheEPRIdata(pp.4-5)(1)inLAREncl.4-3,Ref.[12](p.25).ThetiminganalysisofLAR Encl.4-3,Ref.[12](p.25)isbasedonvisualinspectionof"ltersusedinthe EPRIunquali"edcoatingstesting(p.4-3)(1).These"lterswerechangedin uneventimeincrementsduringtheEPRIautoclavetesting,andthe"lterswere rankedfrom0to10bythedegreeofdiscolorationfortheirrespectivetime increment.Theresultsoftheanalysiswereextrapolatedto30dayswithaforced (normalized)cumulativefailureof100%overalltimeincrements.Awashdown fractionof6.0%(LAREncl.4-3,Ref.[12],Table6,p.30)wasassignedinCASA Grandeforallunquali"edcoatingsthatfailinuppercontainmenttoaccountfor spraysbeingsecuredwithin24hours.The6.0%washdownfractionissupported byanalysisoftheEPRIdataforfailureoccurringwithin24hours.DuringSTP scenarioswherespraysinitiate,allspraysaresecuredcloseto6.5hoursinaccord withEOPswithTechnicalSupportCenter(TSC)concurrences(LAREncl.3-4, Ref.[34]).Thetotalmasses(epoxy,alkyd,etc.)ofunquali"edcoatingsenteredinCASAGrandeweremultipliedthroughtheirrespectivetransportlogictreesofLAR Encl.4-3(Figures5.5.85.5.14,pp.169-172).PercentageslistedintheFraction ofDebrisatSumpcolumnofthetransportlogictrees(LAREncl.43,Figures 5.5.85.5.14,pp.169-172)givethefractionsavailableforactivecirculationin thepoolforeachbranch;thesumofthesefractionsisgiveninthebottomright cornerofeachlogicdiagramgivingthetotalactivecirculationfraction(sum:).

Themassofeachunquali"edcoatingmultipliedbyitsrespectivetotalactive circulationfraction(sum:)istheamountthatwasintendedtobeintroduced intothepoolover36hours(seediscussionofErrorReport#4above),butwas insteadintroducedinthe"rsttimestepinadvertently.Allunquali"edcoatings massesactivelyrecirculatinginthepoolarecalculatedtoarriveatthestrainers accordingtothesolutionsofLAREncl.4-3,Eqn.84.Equation84modelsdebris accumulationasacumulativeexponentialcurvede"nedbythetotalECCS"ow

rate.Consistentwithrespectivebranchesinthetransportlogicdiagrams(LAREncl.4-3,Figures5.5.85.5.14,Pgs.169-172),unquali"edcoatingsmasses(not inuppercontainment)addedtothepoolforactivecirculationarecalculated withEquationAbelow.

MLower (Active)=(M total)(Ffail)(Floc)(Frecirc)(EquationA) where:Tuesday1 stMarch,2016:19:32,Page275of393 DRAFTPART2.RAIRESPONSES(ROUND1)

MLower (Active)=massofunquali"edcoatingsnotinuppercontainmentavail-ableforactivecirculation M total=Totalmassquantityofunquali"edcoatingbytype Ffail=Failurefractionofunquali"edcoating Floc=Locationtransport fraction Frecirc=Transportedlocationfraction(activecirculationfraction)Althoughallunquali"edcoatingsnotinuppercontainmentfailat100%

(Ffail=1),theyarestillmultipliedbytheirrespectivelocationandrecircula-tionfractions.Thelocationfractionfortheunquali"edcoatings(notinupper containment)Flocassignsthepercentageofunquali"edcoatingsthattransport tolowercontainmentandthepercentagethattransportstothereactorcavity (LAREncl.4-3,Section5.5).TheactiverecirculationfractionFrecircassigns thepercentageoffaileddebrisfromalocationthatisactivelycirculating.Mass totalsforeachoftheunquali"edcoatingstypesthatareaddedtothepool foractivecirculation(EquationA)areshownbelowinTableAandTableB forlowercontainmentandthereactorcavity,respectively;wheretransportand failurefractionshavebeentakenfromtheunquali"edcoatingsdebristransport logicdiagramsofLAREncl.4-3(Figures5.5.85.5.14,Pgs.169-172)andtotal massestakenfromLAREncl.4-3,Section2.2.10.Althoughallunquali"edcoatingsnotinuppercontainmentfailat100%

(Ffail=1),theyarestillmultipliedbytheirrespectivelocationandrecircula-tionfractions.Thelocationfractionfortheunquali"edcoatings(notinupper containment)Flocassignsthepercentageofunquali"edcoatingsthattransport tolowercontainmentandthepercentagethattransportstothereactorcavity (LAREncl.4-3,Section5.5).TheactiverecirculationfractionFrecircassigns thepercentageoffaileddebrisfromalocationthatisactivelycirculating.Mass totalsforeachoftheunquali"edcoatingstypesthatareaddedtothepool foractivecirculation(EquationA)areshownbelowinTableAandTableB forlowercontainmentandthereactorcavity,respectively;wheretransportand failurefractionshavebeentakenfromtheunquali"edcoatingsdebristransport logicdiagramsofLAREncl.4-3(Figures5.5.85.5.14,Pgs.169-172)andtotal massestakenfromLAREncl.4-3,Section2.2.10.TableA:Activelycirculatingmassofunquali"edcoatingsfoundinlowercontainment CoatingTypeTotalUn-quali"ed Coatings Mass M totalFailureFrac-tion FfailLocationFraction (LowerCon-tainment)

F locTransported

Recircula-tionFraction

FrecircMassAc-tivelyCircu-lating(lbm)

MLower (Active)Unquali"edAlkyd("nes)271100%46%100%125 Unquali"edEpoxy("nes)234100%2%100%5 Unquali"edEpoxy("ne chips)709100%2%41%6 Unquali"edEpoxy(small chips)180100%2%0%0 Unquali"edEpoxy(large chips)391100%2%0%0 Unquali"edEpoxy (curledchips)391100%2%100%8 Unquali"edIOZCoat-ings("nes)369100%17%100%63

REFERENCES:

Tuesday1 stMarch,2016:19:32,Page276of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableB:Activelycirculatingmassofunquali"edcoatingsfoundinthereactorcavity CoatingTypeTotalUn-quali"ed Coatings Mass M totalFailureFrac-tion FfailLocationFraction (LowerCon-tainment)

F locTransported

Recircula-tionFraction

FrecircMassAc-tivelyCircu-lating(lbm)

MLower (Active)Unquali"edAlkyd("nes)271100%0%0%0 Unquali"edEpoxy("nes)234100%83%0%0 Unquali"edEpoxy("ne chips)709100%83%0%0 Unquali"edEpoxy(smallchips)180100%83%0%0 Unquali"edEpoxy(large chips)391100%83%0%0 Unquali"edEpoxy (curledchips)391100%83%0%0 Unquali"edIOZCoat-ings("nes)369100%0%0%01.ElectricPowerResearchInstitute.DesignBasisAccidentTestingofPres-surizedWaterReactorUnquali"edOriginalEquipmentManufacturerCoatings.

FinalReport:September2005.2.3.5.25ESGB,Coatings:Question5 STPResponse:(Item5,Page60)ThevalueofF(t)is6%.Thevalue(6%)forthe0-24hourtimeperiodwaschosenbecauseitrepresentsanoverpredictionofthetimeinwhichallsprays willbesecuredforLBLOCAs.Yes.F(t)isthesameforallunquali"edcoatingtypes Thecumulativemassesofunquali"edcoatingscalculatedbyLAREncl.4-3,Equation28arenottimedependentandrepresenttheamountofeachunqual-i"edcoatingthatwouldenterthepoolover30daysifsprayswereoperating throughtheentireevent.ThisequationanditsresultsarenotusedintheSTP CASAGrandeevaluationbutvalueshavebeenprovidedinTableBbelow.Thetotalmassesofunquali"edcoatingsthatfailedinuppercontainmentduringthe0-24hourtimeperiodwerecalculatedwithEquation27andare providedinTableA.Additionalinformation F(t)wasassignedavalueof6%forallunquali"edcoatingsinuppercon-tainment,andwasappliedasawashdowntransportfractionintheSTPCASA Grandeevaluation(LAREncl.4-3,Pg.157).OthervaluesofF(t)areprovided inTable6ofLAREncl.4-3,reference12(Pg.30),buttheywerenotappliedin theSTPCASAGrandeevaluation(discussedbelow).F(t)valueswerecalculatedfromEPRIdata(i.,Pg.4-5)foundinLAREncl.4-3,reference12(Pg.25).Theunquali"edcoatingsfailuretiminganalysisof LAREncl.4-3,reference12(Pg.25)isbasedonvisualinspectionof"ltersused intheEPRIunquali"edcoatingstesting(i.,Pg.4-3).These"lterswerechanged inuneventimeincrementsduringtheEPRIautoclavetesting,andthe"lters wererankedfrom0to10bythedegreeofdiscoloration(LAREncl.4-3,Ref.

[12],Pg.25)fortheirrespectivetimeincrement.TheresultsoftheanalysisTuesday1 stMarch,2016:19:32,Page277of393 DRAFTPART2.RAIRESPONSES(ROUND1)performedinLAREncl.4-3,reference12(Table5,Pg.27)wereextrapolatedto30dayswithanarti"ciallyforced(normalized)cumulativefailureof100%over alltimeincrements(LAREncl.4-3,Ref.[12],Table6,Pg.30).The6%value (0-24hourtimeincrement)forF(t)wastheonlytime-relatedfailurefraction assignedinCASAGrandeforunquali"edcoatings.TheF(t)value(6%)forthe 0-24hourtimeperiodwasusedbecauseitrepresentsanoverpredictionofthe timeinwhichallsprayswillbesecuredforlargebreaks(LBLOCA)(LAREncl.

Ref.[35]).AnF(t)of6%wasonlyappliedtocoatingsinuppercontainment.For scenarioswherespraysinitiate,allspraysaresecuredcloseto6.5hours(LAR Encl.3-4,Ref.[34]).Thetotalmassofeachunquali"edcoatingintroducedtothepoolforactivecirculationiscalculatedusingthetotalunquali"edcoatingsmassesprovidedin LAREncl.4-3(Section2.2.10)andtheircorrespondingdebristransportlogic diagrams(LAREncl.4-3,Figure5.5.8Figure5.5.14,Pgs.169172).The totalmassintroducedtothepoolforactiverecirculationincludescontributions fromthe24hour6%washdownfractionrepresentingthetime-dependentfailure F(t).Thesetotalmasseswereintendedtobeintroducedtothepoolatuniform rateover36hours;however,acodelevelerror(CASAGrandev1.6Release Notes,ErrorReport#04)forcedadditiontothepoolofall(activelycirculat-ing)materials,includingunquali"edcoatings,atuniformratesduringthe"rst 10minutes.AccumulationofsuspendeddebrisdoesnotbeginuntilECCSrecir-culationbegins.Thetotalmassofeachunquali"edcoatinginuppercontainmentthatfailsinthe"rst24hours,andisavailablefortransport,iscalculatedusingEquation 27below(LAREncl.43,Pg.157).

M i,j (t)=M total: i,j Ffail: i F (t)(Eq27)where: M i,j (t)=Massofunquali"edcoatingsthatfailduringaspeci"ctimeperiod t=Speci"ctimeperiodfollowingthestartoftheaccidentSubscripti=Unqual-i"edcoatingtype(epoxy,IOZ,alkyd,orbakedenamel)Subscriptj=Coating location(uppercontainment,lowercontainment,orreactorcavity)

M total: i,j=Totalmassofunquali"edcoatings Ffail=Totalfailurefraction F (t)=Fractionofcoatingsthatfailduringaspeci"ctimeperiod M i,j: cum=Cumulativemassofunquali"edcoatingsthatfailThelocationandunquali"edcoatingtype-dependentmass(M total: i,j)iscal-culatedastheproduct M total: i,j=M total F upper(EquationA) where, M total=Thetotalmassofaspeci"cunquali"edcoatingtypeincontainment F upper=Thefractionofaspeci"cunquali"edcoatinginuppercontainmentSubstitutingEquationAintoEquation27andevaluatingwithSTP-speci"cinformationprovidestheresultsshownbelowinTableAfortotalfailedunqual-i"edcoatingsmassfromtheuppercontainmentavailabletotransporttothe sump.Theright-handcolumngivesthemassesofunquali"edcoatings(from uppercontainment)thatareinactiverecirculationduringtheCASAGrandeTuesday1 stMarch,2016:19:32,Page278of393 DRAFTPART2.RAIRESPONSES(ROUND1)simulation.Thesevalues(MijofTableA)mustbemultipliedbytheirrespectiverecirculationfractionsto"ndtheunquali"eddebrisamountsthatareactively recirculatinginthepool.TableA:Totalfailedmassesfromuppercontainmentavailabletothesump CoatingTypeTotalUn-quali"ed Coatings Mass(lbm)

M totalFailureFrac-tion FfailUpperCon-tainmentFraction F upperF(t)Imple-mentedasWashdown Fraction F (t)TotalFailed(0-24hours)MassinUp-perContain-ment(lbm)

M i,j (t=24hrs)Unquali"edAlkyd("nes)271100%54%6%8.8 Unquali"edEpoxy("nes)234100%15%6%2.1 Unquali"edEpoxy("ne chips)709100%15%6%6.4 Unquali"edEpoxy(smallchips)180100%15%6%1.6 Unquali"edEpoxy(large chips)391100%15%6%3.5 Unquali"edEpoxy (curledchips)391100%15%6%3.5 Unquali"edIOZCoat-ings("nes)369100%83%6%18.4ThecumulativemassformulationshownbelowinEquation28(LAREncl.4-3,Pg.157)representstheamountofeachunquali"edcoatingthatwouldenter thepoolover30daysifsprayswereoperatingthroughtheentireevent.The resultsofequation28arenotusedintheCASAGrandeevaluation.

M i,j: cum=M i,j F (t)=M total: i,j Ffail: i(Equation28)SubstitutingEquationAintoEquation28givesresultsforthecumulativefailure(TableB)below.TableB:TotalfailedmassesfromuppercontainmentavailabletothesumpCoatingTypeTotalUnquali"edCoatingsMass(lbm)

M totalFailureFraction FfailUpperContainmentFraction F upperCumulativeFailure(0-24hrs)Massin UpperContainment (lbm)M i,j: cumUnquali"edAlkyd

("nes)271100%54%146Unquali"edEpoxy

("nes)234100%15%35Unquali"edEpoxy("nechips)709100%15%106Unquali"edEpoxy(smallchips)180100%15%27Unquali"edEpoxy(largechips)391100%15%59Unquali"edEpoxy(curledchips)391100%15%59Unquali"edIOZCoat-ings("nes)369100%83%306Thecumulativefailedmassesintherighthandcolumn(M i,j: cum)ofTableBgivetheamountsofunquali"edcoatingsthatwouldenterthepoolover30days ifsprayswereoperatingthroughtheentireevent.Thesevalues(M i,j: cum)werenotusedintheSTPCASAGrandeevaluation.Tuesday1 stMarch,2016:19:32,Page279of393 DRAFTPART2.RAIRESPONSES(ROUND1)

REFERENCE:

1.ElectricPowerResearchInstitute.DesignBasisAccidentTestingofPres-surizedWaterReactorUnquali"edOriginalEquipmentManufacturerCoatings.

FinalReport:September2005.2.3.5.26ESGB,Coatings:Question6a STPResponse:(Item6a,Page60)Thegenerictypeofeachunquali"edcoating(i.e.epoxy,alkyd,etc.)isdocu-mentedintheSTPunquali"edcoatingsinventorylog(LAREnclosure4-3,Ref-erence[12]).Thespeci"cproductdescription,however,isunavailableformany unquali"edcoatings.Productdescriptionsarealsounavailableformanyofthe coatingstestedintheEPRIstudy(LAREnclosure5,Reference[3]),theextent ofcomparisonismadetoapplicablegenericcoatingtypesthatareavailable.2.3.5.27ESGB,Coatings:Question6b STPResponse:(Item6b,Page60)Estimatedfailuretimingofunquali"edcoatingswasbasedonvisualanal-ysisof"lterdiscoloration.Itistruethatthecolorsofcoatingstested "lterdiscoloration.However,itisalsoseenfromtheEPRItestingthatalkyds, themostcolorfulcoatingsgroup,experiencedahigheraveragepercentageof detachmentthanothercoatings(LAREnclosure5,Tables3-1,4-2,Pages3-2, 4-5).Becausealkydcoatingsexperiencedhigheraveragefailureoverthe7-day test,theyarealsoassumedtohavethelargestfailurerate.Thisinterpretation ofthedataimpliesthatranking"ltersbydiscoloration(visuallydominatedby heavilypigmentedalkyds)mayconservativelybiasinferredfailuretimingtothe maximumunquali"edcoatingsfailurerateofalkyds.Asingleestimatedfailure ratewasappliedforallupper-containmentunquali"edcoatingstypesintheSTP LAREnclosure4-3analysis.2.3.5.28ESGB,Coatings:Question6c STPResponse:(Item6c,Page61)Becausealkydcoatingshavethegreatestin"uenceonsubjectiveinterpreta-tionofphotographs(byvirtueofdistinctivecoloration),andhavethehighest averagesubstratedetachment,inferredfailureratescanonlybebiasedtowards themaximumunquali"edcoatingsfailurerateofalkyds.Seediscussioninre-sponsetoESGBRAI6b.Analternativejusti"cationofthe6%failurefractionwithintherelevantmissiontimeproceedsasoutlinedinFigure1below.TheEPRIstudy(LAREnclosure5,Reference[3]),statesWithregardtotimingofthecoatingfailures,the"ltersdonotdemonstrateade"nitivetimeof failure,howeverinsubjectiveterms,itappearsthatmuchofthefailureoccurred inthe24-to48-hourtimeframe.Althoughthereisnode"nitivede"nitionfor thesubjectiveobservation"muchofthefailure,"Figure1showsthreedt scenariosbuiltonavariationintheamountofunquali"edcoatingsthatare estimatedtodetachbetween24and48hours.Thegreencurvedisplaysanend-ingdetachmentpercentageequaltothetotalaveragedetachmentofallSTP analyzedcoatings(epoxy,IOZ,alkyd)overthe7-dayEPRItesting(27%).This curvesetsthemaximumpercentageoffailedunquali"edcoatingsover7daystoTuesday1 stMarch,2016:19:32,Page280of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:FailurePercentageasaFunctionofTime27%andassumesthat21%ofthetotalfailure(from6%to27%total)occurswithinthe24to48-hourperiod.Ifmorethan21%ofthecoatingsfailinthe24-to48-hourtimeperiod,thepercentageofcoatingsthatfailat24hourswillbe shiftedtolessthantheSTPassumed6%failure.Ifthede"nitionofmajority failurewithin24to48hoursischangedto55%oftheavailablefailure,then theassumedfailureat24hrswoulddoubleto12%(linenotshown).Paramet-ricevaluationshaveshownthattotalriskisinsensitivetothisrangeofadded

particulate.If100%failureisarti"ciallyassumedoverthe7-dayperiodandassumethatmuchofthefailurecanbede"nedas89%(from6%to95%)and55%(from 40%to95%),theresultsaretheredandbluecurvesofFigure1,respectively.

Bothcurvesassumea5%residualfailureafter48hours.Itcanbeseenthatif 89%ofthefailureisassumedtooccurbetween24-and48hours,6%willhave tofailbefore24hours.Howeverifitispostulatedthat55%(oneinterpretation ofmajority)mustfailinthe24-to48-hourtimeframe(bluecurve),thefailure before24hourswouldbe40%,whichwouldcontradicttheobservedtotalaverage detachmentof27%.2.3.5.29ESGB,Coatings:Question7 STPResponse:(Item7,Page61)TheSTPcoatingsarecontrolledunderSTPProcedure0PMP06-ZD-0001PaintsandCoatings.Theprogramincludesapplicationrequirements,visual examination,anddocumentationofallconcreteandsteel-coatedsurfacesinthe containmentbuildingtoidentifyanytypeofcoatingdegradationsuchas"aking, peeling,blistering,delamination,rustingandmechanicaldamage.Anyareasof degradationaredocumentedandevaluatedforseverityanddeterminedtobe either:repairedduringthecurrentoutage,repairedinthenextavailableoutage, orcontinuedtobemonitoredandre-evaluatedduringthenextavailableoutage.

[Ref:ASTMD5163-08,para.10.2andpara.11.1.2]TheCoatingAssessmentInspectionincludesavisualexaminationofallac-Tuesday1 stMarch,2016:19:32,Page281of393 DRAFTPART2.RAIRESPONSES(ROUND1)cessibleServiceLevel1coatingsinsidecontainmentincludingthesteelcontain-mentliner,structuralsteel,supports,penetrations,uninsulatedequipment,and concretewallsand"oorsreceivingepoxysurfacesystems.Thisincludesareas nearsumpsassociatedwiththeemergencycorecoolingsystem.TheCoating AssessmentInspectiondoesnotincludecoatingofsurfacesthatareinsulatedor otherwiseenclosedinnormalservice,andconcretereceivinganon-"lmforming clearsealercoatonly.[Ref:ASTMD5163-08,para.10.1]TheCoatingAssessmentInspectionofServiceLevel1coatingsisconductedateachrefuelingoutagebyproperlyquali"edcoatinginspectors;thetimeperiod betweenoutagesisapproximately18months.TheServiceLevel1CoatingsAs-sessmentInspectionisconductedbySTPsCoatingEngineerandCoatingPlan-ner.TheCoatingEngineermeetstheeducational,professionalachievementsand nuclearcoatingsexperiencequali"cationcriteriaforquali"cationasaNuclear CoatingsSpecialistinaccordancewithASTMD7108-05.TheCoatingEngineer istheresponsibleEngineerinchargeoftheSafety-Relatedcoatingsprogram.

TheCoatingsPlannerisacerti"edNACELevelIIIInspectorandmeetsthe educational,professionalachievementsandnuclearcoatingsexperiencequali"-

cationcriteriaforquali"cationasaNuclearCoatingsSpecialistinaccordance withASTMD7108-05.[Ref.ASTMD5163-08,para.6.1andpara9.1].PriortotheCoatingAssessmentInspection,coatinginspectorsreviewthetwopreviouscoatingassessmentreports.Fromtheprevioustwocoatingassess-mentreports,areasidenti"edasbeingmonitoredandre-evaluatedinthenext availableoutagearenotedandaddedtothelocationmapsforthecurrentCoat-ingsAssessmentInspection.[Ref:ASTMD5163-08,para.7.2]ThecoatinginspectorsbringintotheReactorContainmentBuilding(RCB)theproperinstrumentsandequipmentneededforinspection,including,but notlimitedto:locationmaps,"ashlights,markerpen,measuringtape,feeler gauge,binocularsandcamera.Thelocationmapsdividingthereactorcontain-mentbuildingintotwenty-four(24)identi"able"oorplansarelabeledwith pertinentelevation,azimuthreferences,structuralfeaturesandcomponents.All areasofdegradedcoatingsidenti"edduringtheCoatingsAssessmentInspection arerecordedonthelocationmaps.Allareasthatcannotbeinspectedduring theCoatingsAssessmentInspectionandthespeci"creasonwhytheinspection cannotbeconductedareidenti"edonthelocationmaps.[Ref:ASTMD5163-08, para.7.2,para.10.1.3andpara.10.5]Physicaltestsareperformedonanas-needbasisasdeterminedbythecoat-ingsinspectors.Blisteringofallsizes,"aking,peeling,anddelaminationare consideredrejectableconditions.Thesourceandextentofanyrustingisevalu-atedduringthevisualinspectionbythecoatingsinspectors.Cracksover30mils areevaluatedbyEngineeringandallcrackslessthan30milsarearejectablecon-ditionanddocumentedinaccordancewithPGP03ZX0002,ConditionReporting Process.[Ref:ASTMD5163-08,para.10.2]TheCoatingsAssessmentReporthasbeenevaluatedandapprovedbythecoatingsinspectorswhocollaborateintheevaluationofdegradedcoatingsand determinationofrecommendations.TheCoatingsEngineerpreparestheCoat-ingsAssessmentReportandtheCerti"edNACELevelIIICoatingsPlanner preparesworkordersfortherepairofdegradedcoatingsinaccordancewith PGP03ZX0002,ConditionReportingProcess.[Ref:ASTMD5163-08,para.Tuesday1 stMarch,2016:19:32,Page282of393 DRAFTPART2.RAIRESPONSES(ROUND1) 11.1]2.3.5.30SNPB,Question4 STPResponse:(Item4,Page65)ThetimingforboricacidprecipitationisgiveninSTPNOCCalculationNC-7136(Reference1).Thecalculationsummaryfollowsbelow:

OBJECTIVE Thiscalculationdeterminestheeoftheincreaseindeliverablewa-tervolumefromtheRefuelingWaterStorageTank(RWST)onthehotleg switchovertimefollowingalargebreaklossofcoolantaccident(LBLOCA).Hot legswitchover(HLSO)isrequiredtoensurethatboronprecipitationdoesnot occurinthereactorcore.1.4%PowerUprate:TheNRCapproveda1.4%increaseinthereactorcorepowerlevelfrom3,800 MWtto3,853MWt.Theeofthisincreaseisdetermined.Replacementsteamgenerators:Delta-94steamgeneratorswereinstalled.Theeofthischangeisdetermined.INTENDEDUSEOFRESULTS ThiscalculationsupportstheHLSOtimeusedinemergencyoperatingpro-cedure0POP05-EO-EOI0.

SUMMARY

OFRESULTS TheincreaseintheRWSTinjectedvolumehasnegligibleontheHLSOtimefollowingaLBLOCA.IftheRCSvolumeisataboronconcentrationof2830 ppm,themixedsumpboronconcentrationisonlyabout3.3ppmhigherthan previouslyanalyzedwhichiswellwithinmeasurementaccuracy.IftheRCS boronconcentrationisincreasedto3500ppminMode3onehourafterexiting Modes1or2,thenanincreaseinRWSTinjectedvolumeactsasadilutionsource whichisboundedbytheanalysisdocumentedinST-UB-HL-1680previously performed.Therefore,theHLSOtimeof6.0hoursisvalid.However,toensure adequatemarginfortimetoHLSOismaintained,theplantemergencyoperating procedureOPOP05-EO-EOIOspecifyaHLSOtimeof5.5hours.1.4%PowerUprateResultsThecalculationisindependentofreactorpowerlevel(to3853MWt),therefore thepowerupratewillnottheresults.

Delta-94SteamGeneratorResults TheexistinganalysisofrecordisapplicabletoUnits1and2.INTRODUCTION/BACKGROUND Aspartoftherequirementtomaintainthecorecoolablegeometryinthelongterm,Section6.3ofNUREG-0800requiredthatstepsbetakentoprecludetheprecipitationofboroninthevessel.Intheeventofacoldlegbreak,while theECCSisalignedtotheRCScoldlegs,boronconcentrationinthecoreregion increasesduetobofthewater.Toprecludeboronprecipitation,onetrain ofSlisrealignedtotheRCShotlegsatthehotlegswitchover(HLSO)time.ThedesignbasisthatrequiresHLSOisestablishedby10CFR50.46whichrequiresthatthereactorcoremaintainlongtermcoolingafteraLOCAevent.

Duringadouble-endedbreakofthecoldleg,mostofthesafetyinjection"ow entersthecoldleg(s),goesintothedowncomerregionofthereactor vesselandoutthebreakinthebrokencoldleg.Thesafetyinjection"owthatTuesday1 stMarch,2016:19:32,Page283of393 DRAFTPART2.RAIRESPONSES(ROUND1)entersthereactorcoreforthepurposesofcoolingisattributabletothemano-metricpressurebetweenthedowncomerandthereactorvessel.Thisresultsin thesafetyinjection"owboilinginthereactorcoreandleavingassteam.The boronconcentrationofthewaterinthereactorvesselincreasesuntilsuchapoint thatboronprecipitationoccurs.Whenboronprecipitationoccurs,thefuelrods canbecomecoatedandimpedelongtermcoolingofthefuel.Boronprecipita-tionisassumedtooccurwhentheboronconcentrationreaches23.5wt%(41,000 ppm),whichis4wt%lessthantheboronsolubilitylimitofasolutionat2120F.The23.5wt%isanNRCimposedlimit.TheRefuelingWaterStorageTank(RWST),Slaccumulators,andtheECCSpipingaresourcesofthehighestconcentrationofboratedwater.Anincreasein thevolumeofanyoneofthesesourceswillincreasetheboronconcentrationof themixedsumpwaterincontainment,andtherefore,decreasethetimetoboron precipitationinthecore.TheRCS,whichisatalowerboronconcentration, servesasadilutionsourceforthemixedsumpwater.Therefore,anincrease intheprimarysideRCSvolumewillleadtoanincreaseinthetimetoboron

precipitation.AspartofthesetpointreviewethecalculationofthetotaldeliverableRWSTwatervolumehasbeenrevised.Thenewrevisiondocuments(Ref.5)the maximuminjectionvolumeis541,000gallons.Thisnewvalueisgreaterthanthe 453,400gallonsassumedinthesafetyanalysisforthetimetoHLSOfollowing aLOCAevent.SinceanincreaseintheRWSTdeliverablewatervolumewill increasethemixedsumpboronconcentration,theHLSOtimeisexpectedto

decrease.WestinghousehasrevisedtheirmethodologyforcalculatingthetimetoHLSOtocorrectanerrorintheboronconcentrationdensityterm.Thiscor-rectionresultedinaHLSOtimethatdecreasedfrom6.5to6.0hours.Thiswas recommendedbyWestinghousetobeincorporatedintheplantemergencyop-eratingprocedures.However,pertheReportabilityReviewforCR98-5868and USQE98-0032,theHLSOtimewasreducedto5.5hourstoensureboronpre-cipitationwillnotoccurandre"ectedassuchinprocedure0POP05-EO-EO10.InsupportofthelicensingapplicationfortheDelta-94steamgeneratorsandthe1.4%uprate,varioussafetyanalysesarerequiredtobeperformedforthe newsteamgeneratorsorreviewedtocon"rmthecurrentapplicabilityofthe mostrecentanalysis.Thisreviewshowsthatthereisnoeontheresultsof

NC-7136.RESULTS/CONCLUSION TheincreaseintheRWSTinjectedvolumehasnegligibleontheHLSOtimefollowingaLBLOCA.IftheRCSvolumeisataboronconcentrationof 2830ppm,themixedsumpboronconcentrationisonlyabout3.3ppmhigher thanpreviouslyanalyzedwhichiswellwithinmeasurementaccuracy.IftheRCS boronconcentrationisincreasedto3500ppminMode3onehouralterexiting Modes1or2,thenanincreaseinRWSTinjectedvolumeactsasadilutionsource whichisboundedbytheanalysisdocumentedinST-UB-HL-1680previously performed.Therefore,theHLSOtimeof6.0hoursisvalid.However,toensure adequatemarginfortimetoHLSOismaintained,theplantemergencyoperating proceduresOPOP05-EO-EO10hasbeenchangedtospecifyaHLSOtimeof5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.ThisisdocumentedintheReportabilityReviewforCR98-5868.Tuesday1 stMarch,2016:19:32,Page284of393 DRAFTPART2.RAIRESPONSES(ROUND1)ForMode3,theHLSOtimeanalysiswithanincreasedRCSboronconcen-trationto3500ppmfollowingaonehourwaitalterexitingModes1or2is boundedbytheMode1analysisasdocumentedinST-UB-HL-1680.

Reference:

1.STPNOCCalculationNC-7136Rev.1HotLegSwitchoverTimeFollow-ingLOCA2.3.6SSIBResponses 2.3.6.1SSIB,DebrisCharacteristics:Question3 STPResponse:(Item3,Page67)No,Table2.2.21ofLAREnclosure4-3isnotdirectlyimplementedintothehead-losscorrelation.Table2.2.21ofLAREnclosure4-3liststhematerial propertiesofdebris.AsdescribedintheLAREnclosure4-3,Page178,some modi"cationsweremadetothevaluesprovidedinSection2.2.16.Tables5.6.1 and5.6.2presentthematerialpropertiesasimplementedintothehead-loss correlation.Table2.2.21andTables5.6.1and5.6.2arenotidenticaldueto assumptionsrelatedtothehead-losscorrelationandmaterialdebrissizeranges.

Forexample,allLDFGwasassumedtobe"nesintheheadlosscorrelation, whichisnotedasonebetweenthetables.Theeofdebrissizeon risk,selectionofdebrissizeforthehead-losscorrelation,anduncertaintyofthe sizedistributionareexaminedintheresponsetoSSIBRAI24.Uncertaintyin materialpropertiesisaccountedforinthefactorof5uncertaintyboundapplied toallhead-losspredictions.2.3.6.2SSIB,Transport:Question4 STPResponse:(Item4,Page67)Thesteamgeneratorcompartmenttransportfractionswerechosenforthefollowingreasons.

• TransportfractionscalculatedfromtheSteamGeneratorCompartmentarereasonablyconservativeandmaximizetransportforallconsidered breaksexceptthoseintheBelowtheSteamGeneratorCompartmentlo-

cation.*TheSteamGeneratorCompartmenthasamuchlargerTotalPercentageofLDFGwhencomparedtotheothercompartments.

• TheSteamGeneratorCompartmenthasthesecondgreatestCongestiontothePressurizerCompartmentwhichhasnon-conservativetotaltransport

fractions.Thisresponsehasthreesub-parts,whichconsistofanexplanationforas-sumption6.h.iofLAREncl.4-3,Table2.2.22ofLAREncl.4-3,andtheimple-mentationofSGcompartmenttransportfraction.Assumption6.h.iofLAREncl.4-3Assumption6.h.iofLAREncl.4-3states:

I.WorstcasevalueswereselectedfromthetransportfractionrangesforsteamgeneratorcompartmentblowdownandwashdownFigure1illustratesthatthevaluesusedtodevelopoveralltransportfractionlogictreeswerethemaximumvaluesoftherangesinthetransportanalysisandTuesday1 stMarch,2016:19:32,Page285of393 DRAFTPART2.RAIRESPONSES(ROUND1)wereselectedinawayastoresultinthemaximumoveralltransporttothesumpstrainers,exceptfortheerrorasnotedintheresponsetoSSIBRAI7E.InFigure1,Table2.2.22andTable2.2.23areextractedfromLAREncl.4-3.Figure5.12.2istakenfromthedebristransportcalculation(LAREncl.

4-3,Ref.[23]).(Reference23inLAREncl.4-3hasbeenrevisedtoRevision3 (1).However,theprocessillustratedinFigure1isthesameinrevision3asin revision2.)Figure1.IllustrationofProcessDescribedinItemIofAssumption6.hTable2.2.22ofLAREncl.4-3LAREncl.4-3,Table2.2.22summarizestransportfractionsaccordingtobreaklocationforonlytheblowdownportionofoveralltransport.Theother processesthatcontributetooveralltransportarewashdown,pool"ll,andrecir-culation,whosecontributionsarenotre"ectedinTable2.2.22.ImplementationoftheSGCompartmentTransportFractionTheoveralltransportfractionscomputedinrevision3ofthedebristransportcalculation(1)aredisplayedinTable1.Foreachdebriscategorythemaximum valuesarehighlightedinthetable.Thetotaltransportfractionforthesteamgeneratorcompartmentisconser-vativeforindividualLDFGandlatentdebrisbutisnon-conservativeforsmallandlargeLDFG.Asinglebreaklocationstransportfractionswereselectedtomodeltrans-portforallofthebreaksCASAsimulates.Ifbelowthesteamgeneratorcom-partmenttransportfractions(whichgeneratethemostconservativesmalltotal LDFGtransportfraction)wereimplemented,themodelwouldbeaccuratefor thebreaksbelowthesteamgeneratorcompartment,butwouldoverpredicttheTuesday1 stMarch,2016:19:32,Page286of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableA:OverallDebrisTransportFractionsBreakLocationRegionIndividualLDFGSmallLDFGLargeLDFGLatentSGCompartment99%42%1%95%BelowSGCompartment99%60%7%95%

PressurizerCompartment97%31%1%91%

PressurizerSurgeLine97%30%1%91%

RHRCompartment97%30%2%91%

Annulus97%33%8%91%transportforeveryotherbreak.Thesteamgeneratortransportfractionswere implementedbecausetheyarereasonablyconservative.Themodelisaccurate forthebreaksinthesteamgeneratorcompartment,underpredictstheLDFG transportforbreaksbelowthesteamgeneratorcompartment,andoverpredicts theLDFGtransportforallotherbreaks.Table2displaysthetotalvolumeandpercentageofLDFGinthebreaklocationregions.LDFGcongestion(theratioofinsulationvolumetothebreak locationregionvolume)isameasureofthepotentialamountofLDFGthat couldbedestroyedfromasinglebreak.ThismetricisalsodisplayedinTable2; thelargestpercentagesarehighlighted.TableB:InsulationintheBreakLocationRegionsBreakLocation RegionLDFGVol.(ft 3)PercentageoftotalLDFG

(%)RegionVol-ume(ft 3)LDFGConges-tion(%)SGCompartment5,52955201,5522.7 BelowSGCom-partment2783100,7320.3PressurizerCom-partment553610,9335.1PressurizerSurge Line5013,013 1 1.7RHRCompart-ment411431,6981.3Annulus3,16632637,7080.5 2Reference[i]N/ALAREncl.4-3,Ref.[23]

N/A 1ThevolumeofthepressurizersurgelineregionwasnotstatedinLAREncl.4-3Ref.[23];thepressurizersurgelineregionvolumewasincludedinthevolume oftheannulusregion.Thevolumeofthepressurizersurgelineregionwas determinedfromtheCADModelSummary(2).

2Theannulusregionvolumewasdeterminedbyreducingtheannulusregion volume(LAREncl.4-3,Ref.[23])bythepressurizersurgelineregionvolume.ThevaluesinTable2showtheSteamGeneratorCompartmenthastheTuesday1 stMarch,2016:19:32,Page287of393 DRAFTPART2.RAIRESPONSES(ROUND1)largestpercentageofLDFG,rangingfromapproximately2to50timesgreaterthanalltheotherlocations.TheSteamGeneratorCompartmenthasthesecond greatestcongestion.ThecongestionofthePressurizerCompartmentisapprox-imatelytwiceasmuchoftheSteamGeneratorCompartment.However,the SteamGeneratorcompartmenthas10timesmoreLDFGthanthePressurizer Compartment.

References 1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.ALION-SUM-WEST-2916-01.CADModelSummary:SouthTexasRe-actorBuildingCADModelforUseinGSI-191Analyses.Revision4.5/22/2014.2.3.6.3SSIB,Transport:Question6a STPResponse:(Item6a,Page67)Thecapturemetricsareadjustedbyaratioofcoveredareatototalareatoaccountforsituationswheregratingdoesnotfullyspanthetransportpathway, asdescribedinthesteamgeneratorcompartmentblowdownsection(LAREncl.

4-3,Ref.[23],Pg.39).Revision3ofthedebristransportcalculationalsoadheres tothismethodology(1,Pg.47).

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCalculation.Revision3.6/10/2014.2.3.6.4SSIB,Transport:Question6b STPResponse:(Item6b,Page67)Thecomputationalmethodologyforblowdowndidnotalwaysaccountfordepletionofdebrisduetocaptureonupstreamobjects.Anexampleofthisis theequationonpage38ofLAREncl.5,whichispresentedbelow.

F BD=V upper V total(1.0F misc)(1.0F 90turns Nturns)x(1.0Fgrating Ngratings), (EQ-1)where: F BD=fractionofdebrisblowntouppercontainment, V upper=volumeofuppercontainment, V total=totalvolumeincontainment, F misc=fractionofde-bristrappedbymiscellaneousstructures, F 90turns=fractionofdebristrappedbychangesin"owdirection, Nturns=numberofturnsorchangesin"owdirec-tiondebriswouldpassthrough, Fgrating=fractionofdebristrappedbygrating, Ngratings=numberofgratingsdebriswouldpassthrough.

If Nturns or Ngratingsisgreaterthan1(asisthecasefornumerousbreaksinItem5.a.2ofLAREncl.5)themodelwillnotproperlyaccountfordepletion onupstreamobjects.However,Reference23ofLAR.Encl.4-3hasbeenrevisedtoRevision3whichcorrectlyaccountsfordepletionofdebrisduetocaptureonupstreamobjects.

ThemethodologyusedfortheblowdownphaseisbasedupontheequationbelowTuesday1 stMarch,2016:19:32,Page288of393 DRAFTPART2.RAIRESPONSES(ROUND1)inthenewrevision(1,Pg.47):

FUC/LCbd=VUC/LC V total(1.0F misc)(1.0F 90turns)Nturnsxni=0{1.0Fgrating (i)Agratings (i)}, (EQ-2)where: FUC/LCbd=fractionofdebrisblowntoupper/lowercontainment, VUC/LC=volumeofupper/lowercontainment, V total=totalvolumeincontainment, F misc=fractionofdebristrappedbymiscellaneousstructures, F 90turns=fractionofdebristrappedbychangesin"owdirection, Nturns=numberofturnsorchangesin"owdirectiondebriswouldpass through, Fgrating (i)=fractionofdebristrappedbyi-thgrating, Agratings (i)=ratioofi-thgratingareaversustotalblowdownarea(rangefrom0-1), n=Ngratings=totalnumberofgratingsthroughwhichdebriswouldpass.Sincetheoverallamountsbywhichdebrisisaccumulatedonthetobjects,e.g.,grating,miscellaneousstructures,etc.,isdeterminedbyaproduct ofthefactors,thecomputationalmethodologyaccountsfordepletionofdebris asitiscapturedonupstreamobjects.Forexample,iftheonlymechanismof debriscapturewasmiscellaneousstructures,Equation1wouldyield:

FUC/LCbd=VUC/LC V total(1.0F misc)Iffurtherupstreamdebriscaptureoccursfrom90turns,itscapturefactor (1.00F 90turns)Nturnswouldbeappliedtoanalreadyreduced F BDquantitybasedupontheupstreamofmiscellaneousstructures;notontheentire debrisquantity.Likewise,iftheadditionalofgratingsisconsidered,its ni=0{1.0Fgrating (i)Agratings (i)},isappliedtoadebrisquantitythathasalreadybeendepletedbytheeofmiscellaneousstructuresand90turns.Similarly,duringthewashdowntransportphase,theofmultiplegrat-ingsistakenintoaccountwiththeimplementationof Fwdown=F cs F WG (1F AG)(Ngratings1)(LAREncl.4-3,Ref.[23],Equation22andi,Equation24),whereagain,eachsuccessiveholdupisappliedtoaquantitythathasalreadybeendecreased.Therefore,thenewcomputationalmethodologyaccountsfordepletionofdebrisasitiscapturedonupstreamobjectsbyapplyingtheofthe n thmechanismtoanalreadydepletedquantityfromthe1 stto(n1)thmechanism.Tuesday1 stMarch,2016:19:32,Page289of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableB.1displaysthetotaltransportfractionsforbothrevisionsofthede-bristransportcalculations(LAREncl.4-3,Ref.[23]and1).Transportfractions thatchangedinrevision3arehighlighted.SmallandlargeLDFGweretheonly debrisclassi"cationswhosetransportfractionsresultedindtvaluesinre-vision3.ThediscrepancyhasbeenenteredintheSTPcorrectiveactionprogram fortrackingforcorrectioninfuturesubmittals.TableB.1:TotalDebrisTransportFractionsSmallLDFGLargeLDFGBreakLocationRegionRev2Rev3Rev2Rev3SGCompartment37%42%1%1%BelowSGCompartment59%60%7%7%

PressurizerCompartment30%31%8%1%

PressurizerSurgeLine62%30%7%1%

RHRCompartment20%30%4%2%

Annulus27%33%1%8%ACASAGrandeparameterstudywasperformedwherethedebristrans-portfractionsweremodi"edtotheRevision3SGCompartmentvalues.This changeresultedinatotaldecreaseof10%.ThevesselACDFdecreased by25%whilethesumpCDFincreasedby9%.Thecounterintuitiveresult,a decreaseintotalwhentheamountofdebrisreachingthestrainerwas increased,isattributedtocompetingphenomena.Byincreasingdebristransport fractions,greaterinitialtransportcausesthe"ltrationofthedebris bedtoincrease,whichinturnallowslessdebristopenetratethestrainerresult-inginsigni"cantlylowerin-vesselCDF.Conversely,theadditionaldebrisat thestrainercausesanincreaseinheadlossandsump-relatedHowever, thecompetingphenomenaweredominatedbythe"ltrationandre-ductionofin-vesselCDF.SimilarinstancesweredocumentedinScenarios1 and2ofpreviousparameterstudies(2,AppendixA)whereadecreaseinlatent "berresultedinanincreaseandanincreaseinlatent"berresultedina decreaseof

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.5SSIB,Transport:Question6c STPResponse:(Item6c,Page67)Reference23ofLAREncl.4-3included90turnsthatwerenotwellrepre-sentedbytheDDTS.However,Reference23ofLAREncl.4-3wasrevisedto Revision3(1)whichonlyconsidered90turnscomparabletotheDDTStestset-upandexpectedresultantdebrisentrapmentpatternasdescribedbelow.Tuesday1 stMarch,2016:19:32,Page290of393 DRAFTPART2.RAIRESPONSES(ROUND1)AreviewofNUREG/CR-6369,DrywellDebrisTransportStudy(DDTS),showsthatthe90bendinthetestset-upwasnotdesignedtosimulateanyspeci"cfeatureofaBWR;the90bendsimplysimulatedaconditionwheredebris-ladenblowdown"owwasforcedtochangeitstrajectoryby90(0).ThesubsequentthreestatementsarequotesfromtheDDTS.Thedebriswasthencarriedbytheair"owover20-ftlongstructuralcongestion,a90bend,andaMarkIvententrance,allofwhichwerepre-wetfedbywarmwatertosimulatesurfacewetnessIn addition,thedebristransportpathwaypassedthrougha900bend.

Thediameterofthetestchamberwasapproximately10ftandthe totaltransportpathlengthwasapproximately70ft....makea900 bendwherethechamberwallhadbeenwettedbymistdriftingwith theslightairdraftthroughthechambers.Asubstantialamountof debriswasdepositedatthisbendandthisdepositionexpressedasa capturefractionisshowninFigure3-35asafunctionofthedebris passingthroughthecollartotheauxiliarychamberintermofmass "uxbasedonthecross-sectionalareaofthechambers,notthecollar.

Themeanvalueforthewettestswas17%.Notethatthecross-sectionalareaofthecollarwasabout60%ofthemainchamberarea andthatthemeancapturefractionbasedonthecollarcross-sectional areawouldbeabout28%.Hence,intheabsenceofanyotherfactors,thetestset-upandresultingdebrisentrapmentassociatedwiththe900bendisequallyapplicabletoaBWR,PWR orothersimilarindustrialfacility.Applicationofthetransportreductionfactorsassociatedwitha90bendinthetransportcalculationwasdonewithconsiderationoftheDDTStestset-up andexpectedresultingdebrisentrapmentpattern.Forexample,blowdownuptouppercontainmentfromeitheraSteamGen-eratorcompartmentbreak,orabreakinpipingintheannulusoutsidetheSec-ondaryShieldWallwouldresultinsomeamountofchangeintrajectoryfrom vertical.Howeversuch"owpathswerenotconsidered900bendsbecausethe changeintrajectorywasjudgedtobelessacutethanthatintheDDTStest set-upandwouldnotresultinthetypeofdebrisaccumulationillustratedin Figure3-25Depositioninauxiliarytankatbend(TestH2)oftheDDTSwhich isdisplayedbelow.Tuesday1 stMarch,2016:19:32,Page291of393 DRAFTPART2.RAIRESPONSES(ROUND1)Conversely,reliefofcompartmentpressurizationthroughgratedopeningincornersof"oors,which(a)requiredanacute90trajectorychange,and(b)whichwouldleadtoadebrisdepositionpatternonthewallatthevertexof

90bendwhichwouldbesimilartotheoneillustratedinDDTSFigure3-25,wereconsideredtohavedebrisentrapmentsimilartothatdescribedinthe

DDTS.Compartmentsthatforcedtheblowdownjettogothrougha180hairpinturn,suchastheaccesswaystoRHRCompartments,wheredebrisentrapment patternssimilartotheoneillustratedinDDTSFigure3-25wouldbeformed inoneormorecorners,andwhichclearlyhadacutetrajectorychanges,were consideredtohavedebrisentrapmentsimilartothatdescribedintheDDTS.TableClsummarizesthepositionsintheSTPcontainmentatwhich90turnswereconsideredtoproduceadebrisentrapmentpatternsimilartotheonesob-servedintheDDTS(1).Insummary,the90bendintheDDTStestset-upisequallyrepresentativeofaBWR,PWRorothersimilarindustrialfacility.Thedeterminationofthe applicabilityofDDTStest90bendentrapmentresultswasbasedupontheexpecteddebrisdepositionpatterninSTP90bendlocationsbeingsimilartothatshownintheDDTS.TableC.2displaysthetotaltransportfractionsforbothrevisionsofthedebristransportcalculations.Transportfractionsthatchangedinrevision3are highlighted.SmallandlargeLDFGweretheonlydebrisclassi"cationswhose transportfractionsweremodi"edinrevision3.Insummary,the90bendintheDDTStestset-upisequallyrepresentativeofaBWR,PWRorothersimilarindustrialfacility.Thedeterminationofthe applicabilityofDDTStest900bendentrapmentresultswasbaseduponthe expecteddebrisdepositionpatterninSTP900bendlocationsbeingsimilarto thatshownintheDDTS.ChangestototaldebristransportfractionsarediscussedintheresponsetoSSIBRAI6b,above.

References:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10//2014.Tuesday1 stMarch,2016:19:32,Page292of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableC.1: 90TurnPositionsintheSTPContainmentBreakLocationFlowpathto:DTCalcEqua-tionNumbersDiscussionof90bendsSteamGeneratorCompartmentsUpperContainment2and3No90bendswereconsideredSteamGeneratorCompartmentsSumpElevation4and5One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating; the90bendisformedby"oor/wallintersection.ReactorCavityUpperContainment2and3No90bendswereconsideredReactorCavitySumpElevation4and5One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating; the90bendisformedby"oor/wallintersection.BelowtheSteamGeneratorCom-partmentFloorUpperContainment6and7One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating;the90bendisformedby"oor/wallintersection.BelowtheSteamGeneratorCom-partmentFloorSumpElevationN/ANo90bendswereconsideredPressurizerCom-partmentUpperContainment8and9One90bendmodeledtheturntoexittheopeningsatthetopofthePressurizerCompartment;the90bendisformedby"oor/wallintersection.PressurizerCom-partmentSumpElevation10and11One90bendmodeledtheturntoexittheopeningsatthebottomofthePressurizerCompartmentenroutetogratings;the90bendisformedby"oor/wallintersection.PressurizerSurge LineUpperContainment12and13Two90bendmodeledtheexitatthebottomofthePressur-izerCompartmentenroutetogratings;the90bendisformedby"oor/wallintersection.PressurizerSurge LineSumpElevation14and15No90bendswereconsideredRHRCompart-mentsUpperContainment16and17Two90turnsarerequiredtoexitthecompartments(whichelyisa180hairpinturn);the90bendisformedbywalls/wallsintersectionsRHRCompart-mentsSumpElevation18and19Two90turnsarerequiredtoexitthecompartments(whichelyisa180hairpinturn);the90bendisformedbywalls/wallsintersections.AnnulusUpperContainment20and21No90bendswereconsideredAnnulusSumpElevation22and23No90bendswereconsidered[1]DTreferstoRevision3ofReference23ofLAREncl.4-3(1)TableC.2:TotalDebrisTransportFractionsSmallLDFGLargeLDFGBreakLocationRegionRev2Rev3Rev2Rev3SGCompartment37%42%1%1%BelowSGCompartment59%60%7%7%

PressurizerCompartment30%31%8%1%

PressurizerSurgeLine62%30%7%1%

RHRCompartment20%30%4%2%

Annulus27%33%1%8%2.NUREG/CR-6369,Volume2.DrywellDebrisTransportStudy:Experi-mentalWork.September1999.3.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.6SSIB,Transport:Question6d STPResponse:(Item6d,Page67)Speci"climitshavenotbeenplacedonthemassofdebristhatiscomputedtobecaughtonstructures.However,afeasibilitycheckhasbeenperformedand isdiscussedbelow.Thefeasibilitycheckfocusedonestimatingthemaximum crediblequantitiesofLowDensityFiberglass(LDFG)debristhatisconsideredTuesday1 stMarch,2016:19:32,Page293of393 DRAFTPART2.RAIRESPONSES(ROUND1)tobecaughtonstructuresandcomparingthesequantitieswiththequantitiesthatwereobservedintheDDTS.Resultsshowedthatthequantityofdebris computedtobehelduponSTPstructureswaslessthanthoseobservedinthe DDTStestprogram,whichcon"rmsthatDDTStestresultsareapplicableto STPconditions.Thefeasibilitycheckconsistsofa.DeterminingthemaximumquantitiesofLDFGgeneratedforcasesthatresultedinsuccessfulECCSoperationandhadprobabilitiesofoccurrence greaterthan1.0E-15,Itwasdeterminedthat100cubicfeetofLDFGwasthemaximumtotalSTPLDFGquantityforcasesthatresultedinsuccessfulECCSopera-tionandhadprobabilitiesofoccurrencegreaterthan1.0E-15.Casesthat resultedinfailurewerenotofinterestbecauseifalimitonastructure allowedmoredebristobypass,thecasewouldstillresultinfailure.b.EstimatingthetotalquantitiesofLDFGdebriscomputedtobehelduponSTPStructuresand90bendsduringblowdownphase,c.EstimatingtheportionofthetotalquantitiesofSTPLDFGdebriscom-putedtobeheldupthataresmallpieces,d.DeterminingtheareaofstructuresonwhichthemaximumquantitiesofSTPLDFGsmallpieceswerecomputedtobeheldup,e.ComputingthequantityofSTPLDFGsmallpiecedebrisperunitareaofSTPstructures,Themaximumquantitiesofdebrisaccumulationon gratingresultsfromsteamgeneratorcompartmentbreakcases.Itwas determinedthatifthemaximumquantitySTPLDFGongratingwasinthe formofoneinchcubes,approximately11%ofthegratingconsideredwould becovered.Likewise,itwasdeterminedthatifthemaximumquantitySTP LDFGongratingwasintheformoftwoinchcubes,approximately3%

ofthegratingconsideredwouldbecovered.Accumulationfrombreaksin otherlocationsisanorderofmagnitudeless.Themaximumquantitiesofdebrisaccumulationonmiscellaneousstruc-turesresultsfromSteamGeneratorcompartmentbreakcases.Itwasalso determinedthatifthemaximumquantitySTPLDFGonmiscellaneous structureswasintheformofoneinchcubes,approximately7%ofthe structuresconsideredwouldbecovered;anditwasdeterminedthatifthe maximumquantitySTPLDFGonstructureswasintheformoftwoinch cubes,lessthan2%ofthemiscellaneousstructuresconsideredwouldbe covered.Accumulationfrombreaksinotherlocationsareanorderofmag-nitudeless.f.ComparingthequantityofSTPLDFGsmallpiecesdebrisperunitareaonSTPstructuresversusDDTSresults.BaseduponavisualcomparisonwithtestresultsshowninDDTSFigures2-9,2-10,2-11,3-21,3-22and3-23,maximumgratingcoverageof3%Tuesday1 stMarch,2016:19:32,Page294of393 DRAFTPART2.RAIRESPONSES(ROUND1)to11%iscomparabletowaswhatobservedinDDTStests.TableD1illustratesthiscomparison.ThemaximumquantityofdebrisaccumulationfromSteamGeneratorcom-partmentbreaksonmiscellaneousstructureswouldresultincoverageof2%to 7%ofthemiscellaneousstructuressurfacearea.Baseduponavisualcomparison withtestresultsshowninDDTSFigures2-7and2-8,thisiscomparableorlessTuesday1 stMarch,2016:19:32,Page295of393 DRAFTPART2.RAIRESPONSES(ROUND1)thanwaswhatobservedinDDTStests.TableD2illustratesthiscomparison.However,sincetheminimumoftherange(0%)ofholduponstructureswasusedinthetransportanalysisforSteamGeneratorcompartmentbreaks,the aboveresultsaretheoretical.Inpractice,itisconsideredthatnoaccumula-tiononmiscellaneousstructureswouldoccurforSteamGeneratorcompartment breaks.ForbreaksbelowtheSteamGeneratorcompartment,theRHRCom-partmentsandannulus,accumulationofdebrispersurfaceareaofstructures islessthanwhatisreportedintheDDTStestresults(DDTSTable2-2).On thebasisofthesecomparisonswithDDTSresults,itwasconcludedthatthe quantitiesofSTPLDFGcomputedtobeheldupongratingandmiscellaneous structureswerefeasible.TheDDTSdidnotfurnishnumericalquantitiesofde-briscollectionat90bends.Themaximumquantityofdebriscollectionata900 bendintheassessmentwasequivalenttoa1.8-ftcubeofLDFG.Thismaximum quantityisassociatedwithsteamgeneratorcompartmentbreaks.Debrisquan-titiesassociatedwithbreaksinotherlocationsareanorderofmagnitudeless.

Giventheplantgeometrieswheresuchretentioncanbeexpected,thereisno physicalreasonwhysuchaccumulationcouldnotfeasiblyoccur.Tuesday1 stMarch,2016:19:32,Page296of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.7SSIB,Transport:Question6eSTPResponse:(Item6e,Page67)SeveralparameterswereusedtoconcludethatthevaluesdeterminedintheDDTSareapplicabletoSTP.Theseare:a.debristypeusedintheDDTSversusdebristypetowhichDDTSvalueswereappliedtoSTP,b.debrissizeforwhichcapturefractionsarereportedintheDDTSversusthedebrissizeforwhichDDTScapturefractionsareusedinSTPdebris transportcalculations,c.thedegreetowhichthewettedconditionsthatresultedinsigni"cantdebrisentrapmentintheDDTSaresimilartotheconditionsthatcanbeexpected atSTP,d.thetypesofstructuraldebrisentrapmentsthatwereinvestigatedintheDDTSversusthetypesofstructuraldebrisentrapmentsthatarefoundat

STPe.thecongestionandjetvelocitythatwereusedintheDDTSversuswhatisexpectedatSTP,f.orientationoftheDDTStestset-upversusapplicationforSTPg.themannerinwhichtheresultsoftheDDTSwereintendedtobeusedversustheintendeduseforSTP,h.considerationofoveralldebrisquantitiesconsideredintheDDTSandex-pectedtooccuratSTP.Eachitemisdiscussedbelow.Thediscussionestablishesthebasisforcon-cludingthatthedebrisentrapmentvaluesreportedintheDDTS,asused,are applicabletoSTPconditions.DebrisType ThedebristypeinvestigatedintheDDTSwasLowDensityFiberglass(LDFG).NUKONwasusedasthetestmaterial.TheresultsoftheDDTSareappliedto potentialLDFGPost-LOCAgenerateddebrisatSTP.ThisDDTScharacteristic isdirectlyapplicabletoSTP.DebrisSizeAssumption3.1.b(LAREnclosure4-3,Reference[23]and1)statesItwasassumedthatsmallpiecesofLDFG(smallerthan6")canbetreatedas1 clumps,andlargepiecesofLDFG(largerthan6)canbetreatedas6pieces.

Sincetheassumedsizesareonthelowendofthesizerangesdescribedinthe debrisgenerationcalculation(2),thisisaconservativeassumption.TheDDTSSeparateTestProgramsuppliedrangesofnumericalen-trapmentfractionsforsmalldebris.IntheSeparateTestProgram, smalldebris,calledClass2-4,wasofthesizeshowninDDTSFigure2-6.The DDTSSeparateTestProgramsmallpiecesweregenerally2incheslong; somewerecloseto4inches,butnoneareaslargeasthe6inchsizethatwasTuesday1 stMarch,2016:19:32,Page297of393 DRAFTPART2.RAIRESPONSES(ROUND1)includedinthesmallpiecesofLDFG(LAREnclosure4-3,Reference[23]and 1).ThedebrissizedistributionusedintheIntegratedEprogramisshowninDDTSTable3-7.Rangesofnumericalentrapmentfractionsweredeveloped forsmalldebris;entrapmentestimatesformediumandlargedebriswerequal-itative.TheDDTSIntegratedESmallsize,de"nedasbeingabletopass throughagratingcell,issigni"cantlysmallerthanthesmallpiecesofLDFG, whichwereupto6inches(LAREnclosure4-3,Reference[23]and1).Insummary,thesizerangeofsmallpiecesofLDFGinthedebristransportcalculation(LAREnclosure4-3,Reference[23]and1)weresubstantiallylarger thantheClass2-4andsmallsizesforwhichentrapmentfactorswerereported ineithertheSeparateTestProgramortheIntegratedEprogram.DDTSstudiesstatedthatentrapmentincreasedwithdebrissize,particularlyforgrating.Consequently,usingDDTSentrapmentfactorsbaseduponsigni"-

cantlysmallerdebristhanconsideredinthedebristransportcalculation(LAR Enclosure4-3,Reference[23]and1)isasigni"cantconservatism,particularly wheregratingentrapmentisconcerned.WhilenotstatedintheDDTS,itisreasonabletoconcludethatat90bends,largersmallpiecesofLDFG(LAREnclosure4-3,Reference[23]and1)debris wouldbeequallyormorelikelytocollectincornersthantherelativelysmaller Class2-4andSmalldebrisconsideredintheDDTS.Onthatbasis,particularlygratingand90bendentrapmentestimatesintheDDTSareapplicabletoSTPandareasourceofconservatisminthedebris transportcalculation(LAREnclosure4-3,Reference[23]and1).WettedConditionsTheDDTSconcludedthatsubstantialdebrisentrapmentonstructuresoc-curswhenthestructuresarewetted,whilelessdebrisiscaughtondrysurfaces.

Gratingwaslesssusceptibletoentrapmentbetweenwettedanddry conditions.GiventhataLOCAjetatSTP,beingaPWR,beginswithatwo-phasemixture,itisreasonabletoconcludethattheSTPjetwilltly wetthesurfaceincomparisontothearti"ciallyintroducedwettingthatwas doneintheDDTStestset-up.Consequently,thisDDTSwetnesscharacteristic isdirectlyapplicabletoSTP.StructuralDebrisEntrapmentsTypesThestructuraldebrisentrapmentstructuresusedintheDDTSwerepipe,structural(I)beams,grating,a90turnandaMarkIIvententrance.TheDDTSinvestigatedseveralcombinationswithupstreamanddownstreamstructuralel-ements.Ingeneral,withtheexceptionoftheMarkIIvententrance,thetypes ofentrapmentstructuresusedintheDDTSaresimilartothosewhichexistat STP.ThisDDTStestset-upcharacteristicisdirectlyapplicabletoSTP.CongestionandJetVelocity Congestion.GiventhesizedbetweenBWRandPWRcontain-ments,itisrecognizedthatBWRcontainmentstendtobemorecongested.

Intuitively,itwouldappearthatincreasedcongestionwouldresultinincreased debrisentrapment.Whilegenerallytrue,theDDTSalsostatesinsection2.4.7, ofStructuralCombinations,fordownstreamobstructionsinaheavilycon-gestedcon"guration,thedebrisretentionabilityofthe(downstream)beamsis reducedwhentheyarelocatedintheturbulenceofthewakeregionbehindup-Tuesday1 stMarch,2016:19:32,Page298of393 DRAFTPART2.RAIRESPONSES(ROUND1)streammembers.Therefore,congestion,alone,isnotacompleteparameterondebrisentrapmentorapplicabilitytoaparticularcon"guration.JetVelocity.Bothforstructuralelementsandgrating,theDDTSreportedinsection2.4.3,ofApproachVelocity,thegeneraltrendthatincreasing jetapproachvelocitytendedtoresultindecreasingdebriscapturee.

AssumingthattheDDTSwasareasonablyscaledrepresentationofaBWR containment,andgiventhatPWRsingeneralandSTPinparticularwouldhave arelativelylargervolume,itisreasonabletoexpectthatthegenerallylarger volumewouldresultinequalorlowerapproachvelocitiesasthePWR/STP jetpropagatesthroughcontainment.Asaresult,itisnotexpectedthatbased uponvelocity,agenericPWRorSTPwouldhavecaptureethatare substantiallylowerthanwhatwasreportedintheDDTS.Withtheeofcongestionbeingsomewhatmoderatedbythepotentialoflocalturbulence,andgiventhatlowerapproachvelocitiestendedto resultingreaterdebriscapturee,itisreasonabletoconcludethatwhere thesetwoparametersareconcerned,theresultsoftheDDTSaregenerallyap-Tuesday1 stMarch,2016:19:32,Page299of393 DRAFTPART2.RAIRESPONSES(ROUND1)plicabletoSTP.OrientationoftheDDTSTestSet-upTheorientationofallthetestjetsintheDDTSwashorizontal.However,resultsofDDTStestareusedforanalysisofhorizontalandverticaljetpropa-gations.ItisnotedinItemviiinsection2.5(Conclusions)oftheDDTSthat thelossof"brousdebrisbycaptureonthetunnel"oor,wasnegligibleforall testsexcepttheMARKIIventgeometry,theresultsofwhichwerenotusedin theSTPanalyses.Therefore,resultsoftheDDTSareacceptableforapplication ofhorizontalandverticaljettrajectories.DDTSResultsUsageDDTSFigure3-31illustratesthefractionalcaptureofsmalldebrisbyI-beamsandpipes.ValuesinDDTSFigure3-31forCEESIwettedtestsrange fromapproximately7%to14%.Theminimumandmaximumentrapmentvalues usedinthedebristransportcalculation(LAREnclosure4-3,Reference[231and 1)are0%to13%,whicharelowerthanthoseshowninDDTSFigure3-31.DDTSFigure3-32illustratesthefractionalcaptureofsmalldebrisbyV-grating.ValuesinDDTSFigure3-32forCEESIwettedtestsrangefromap-proximately21%to36%.DDTSFigure3-33illustratesthefractionalcapture ofsmalldebrisbysplitgrating.ValuesinDDTSFigure3-33forCEESIwetted testsrangefromapproximately16%to38%.DDTSFigure3-34illustratesthe fractionalcaptureofsmalldebrisbycontinuousgrating.ValuesinDDTSFigure 3-34forCEESIwettedandpartiallywettedtestsrangefromapproximately3%

to29%.Theminimumandmaximumentrapmentvaluesusedindebristrans-portcalculation(1)are5%to35%,whicharelowerthanthoseshowninDDTS Figures3-32and3-33,andaresimilartothoseinDDTSFigure3-34giventhat thelowendoftherangeinDDTSFigure3-34isstronglyin"uencedbypartial versussigni"cantwetting.DDTSFigure3-35illustratesthefractionalcaptureofsmalldebrisbytheauxiliarytankbend,i.e.,the900bend.ValuesinDDTSFigure3-35forCEESI wettedtestsrangefromapproximately3%to31%.Theminimumandmaximum entrapmentvaluesusedinthedebristransportcalculation(LAREnclosure4-3, Reference[23]and1)are3%to29%,whicharewithintherangeshowninDDTS Figure3-35.ItisnotedthatinDDTSFigure3-31smalldebriscapturefractionsbyI-beamsandpipesrepresentindividualobstructions.Therefore,formultiplestruc-turalelements,aformulationsimilartothatwhichwasusedfor90bendsandgratingareappropriate,i.e.,oftheform ni=0 (1.0F misc)where F miscisthecapturefractionofonemiscellaneousstructuralobstruc-tionand ninthe n=N miscwhichdenotesthenumberofsuchobstructionstobemultipliedinthe1CartesianProduct.Instead,thedebristransportcalculation (LAREnclosure4-3,Reference[23]and1)uses,inasingleterminall cases,whichisaconservativeapproach.OverallDebrisQuantitiesTuesday1 stMarch,2016:19:32,Page300of393 DRAFTPART2.RAIRESPONSES(ROUND1)IntheSTPCASAGrandeanalysis,over640,000breakcases,ranginginloca-tion,breaksizeandprobabilityofoccurrence,areconsidered.Ofthese,breaks resultingintotalLDFGdebrisgeneratedinexcessof100cubicfeethavea probabilityofoccurrenceinthe1.0E-15range,hencetheyareoflittlepractical interest.ThequantitiesofLDFGdebrisconsideredhelduponmiscellaneous structures,gratingandat90-degreeturnsforbreakcasesassociatedwithtotal LDFGdebrisgeneratedupto100cubicfeetarerelativelysmallwhencompared withthequantitiesofdebrisheldupintheDDTStests.Consequently,there-sultsoftheDDTStestingareapplicabletoSTPconditionsintermsofquantities ofdebrisconsideredtobehelduponmiscellaneousstructures,gratingandat 90-degreeturns.

SummaryInsummary,baseduponsimilarityindebristype,debrissizesconsidered,thedegreetowhichwettedconditionscanbeexpected,similarityintypesof structuraldebrisentrapments,congestionandjetvelocitycomparison,theman-nerinwhichtheresultsoftheDDTSwereusedandoveralldebrisquantities,it isconcludedthat,asused,theresultsoftheDDTSwereappropriatelyapplied toSTPconditions.

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3,6/10//2014.2.3.6.8SSIB,Transport:Question7a STPResponse:(Item7a,Page68)Section2.2.18,WashdownTransportFractions,ofLAREnclosure4-3doesnotcontainanexplicitevaluationofthelikelihoodthatapieceofdebristhat hasbeenblownthroughoneormoregratingswillbemorelikelytosubsequently washdownthroughgratings.NUREG/CR-6369,Vol.2DrywellDebrisTrans-portStudy:ExperimentalWorkFinalReport(DDTS)didnotattachtestdebris togratingbyimpingementinajetthroughgratingswhenstudyingwashdown

(1).However,basedonthefollowing,itisconcludedthatthedebristhatwasusedinsection4oftheDDTS,SeparateTestProgramtoEvaluateWashdown ofInsulationDebrisbyECCSFlow,(hereafterreferredtoaswashdown)ad-equatelyrepresentsthedebristhatwasconsideredsusceptibletowashdownin theSTPanalysis,andtheresultsoftheDDTScanbeappliedtoSTPwashdown

calculations.Section5.4ofreference23inLAREnclosure4-3states,forthisanalysis,itwasconservativelyassumedthatalldebriswouldbewashedtolowercontain-mentwiththeexceptionofanysmallandlargepiecedebrisheldupongrating asitiswasheddown.IntheDDTSwashdowndiscussion,Smallwashdown debris,isdescribedas:Insulationdebrisofalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.Typicallythesepieceswereabout1.5 insizeandpossessedlittleoftheoriginalstructureorthechemical binding.InCEESItests,theywerefoundtohavebeenattachedtoTuesday1 stMarch,2016:19:32,Page301of393 DRAFTPART2.RAIRESPONSES(ROUND1)thewetgratings.Thesedebrispieceswereobtaineddirectlyfromblast-jetexperimentsconductedpreviouslybySEA(seeSection3).

Thesedebrispiecesweremainlyusedinspraytests.Notethecharacterizationofalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.TheDDTSwashdowndiscussionstatesthatcompacteddebris islesspronetoerosion,whileloosedebrisismorelikelytoerode.Forexample, DDTSwashdownsection4.4.1,Con"rmatoryTests,item3statesPieces cientlylargerthanthegrating(classi"edasM-O,M-JandLinSection4.2.2) possesststructureandarenotsusceptibletobeingforcedthroughthe gratingclearancesinashortperiodoftime.Erosion(ifany)occursoveralonger periodoftime.Themechanismofdebrisgeneration,passagethroughagratingandsubse-quentcaptureonagratingisasfollows:a.Theprocessofdebrisgenerationdestroystheinitialcompactformofde-bris.b.Theprocessofdebris,whichislargerthantheopeningsizeofthegrating,passingthroughalevelofgratingfurtherdisruptsthecompactnessofthe

debris.c.Theprocessofinertialcaptureofdebrisongratingincludescompactionasthedebriscollideswiththegrating,underthein"uenceofjetforces.As moredebrisiscaughtonthegrating,thedebrisisfurthercompacted,both undertheactionofthejetforcesactingonitandtheeof"additional layers"beingcompressedbyjetforces.Therefore,whiletheprocessofpassingthroughalevelofgratingmayloosendebris,theprocessofcaptureandretentionhastheoppositecompaction.

Forexample,insection2.4.10,GratingDebrisDegradationTests,oftheDDTS, itwasobservedthatdebriscaughtongratingandsubjectedtojetforcestended toretainitsstructure,e.g.,Noapparentbreakdownofeitherthe1/2or1/4" insulationdebriswasseen,althoughthepiecesbowedbetweenthegratingbars andtheedgesoftheinsulationpieceswrappedbackaroundthegratebarsto "apbehindthegrate...Incontrast,thedebrisusedinthewashdowntestshada...alight,loose,andwell-aeratedtexture...Itisthereforeconcludedthatresultsobtained fromwashdowntestingof...light,loose,andwell-aeratedtexturedebrisis representativeandmaybeconservativewhencomparedtodebristhathasbeen compactedongratingbyacombinationofjetforcesandpotentiallymultiple layersofdebris.

Reference:

1.NUREG/CR-6369,Vol.2.DrywellDebrisTransportStudy:ExperimentalWorkFinalReport.September1999.2.3.6.9SSIB,Transport:Question7b STPResponse:(Item7b,Page68)Tuesday1 stMarch,2016:19:32,Page302of393 DRAFTPART2.RAIRESPONSES(ROUND1)Thesigni"cantlylongerwashdownperiodsatSTPthanthoseconsideredintheDDTSareinconsequentialtotheSTPanalysis.SectionVl.5,Blow-down/WashdownConclusion,ofNEI04-07Vol-2(SER)(LAREnclosure4-3, Reference[45])whichisguidancethataddressestheentirepost-LOCAmission timeonadeterministicbasis,states:theDDTSassessedtheerosionofLDFG byCSs(i.e.,spray)aslessthan1percent.Inreality,theerosionmaybesigni"-

cantlylessthan1percent.The1percentvaluewasassumedtobeconservative butnotfarfromreality.Thebasisofthewashdownparametersusedinthe transportanalysiswasNEI04-07Vol-2(SER),nottheDDTS.2.3.6.10SSIB,Transport:Question7c STPResponse:(Item7c,Page68)Thedebristransportanalysistakesintoaccountthepossibilitythatdebristhatiswasheddownthroughonelevelofgratingmaybemorelikelytowash throughsubsequentlevels.Section5.4ofreference23inLAREnclosure4-3statesTheresultsoftheDDTStestingshowedthatapproximately40-50%ofsmall"berglassdebrisland-ingongratingwouldbewashedthroughthegratingduetospray"ows(14).

Duetothefactthatmanyofthe"owpathstothecontainmentpoolwouldpass throughmultiplelevelsofgrating,itwasassumedthat0-25%ofsmallpieces wouldbehelduponeachadditionalgratinglevel...Inthetransportcalculation,theaboverangeswereimplementedasfollows:

• Forthe"rstgrating,a50%fractionwasused,resultingin50%hold-upand50%washthrough.

• Forallsubsequentgratings,a0%fractionwasused,thusresultinginnoholdupofdebrisatsubsequentgrating(s).Thisapproachtakesintoaccountthepossibilitythatdebriswasheddownthroughonelevelofgratingmaybemorelikelytowashthroughsubsequent levels.ItisnotedthattheDDTSdoesnotincludeanydiscussionthatitmay bemorelikelyforapieceofdebristhathasbeenblownthroughonelevelof gratingstobemorelikelytowashthroughsubsequentlevels.Nevertheless,itis concludedthatthedebristransportanalysistakesintoaccountthepossibility thatdebristhatiswasheddownthroughonelevelofgratingmaybemorelikely towashthroughsubsequentlevels.2.3.6.11SSIB,Transport:Question7d STPResponse:(Item7d,Page68)TheresponsetoSSIB,Transport,RAI8statesTheresponsepreviouslypro-videdinSection5.a.5(LAREnclosure5)wasnotimplemented.CASAGrande assumesnocreditforholdupofpartiallysubmergeddebrisontheconcreteof theoperatingdeckaspreviouslydescribed.ThishasbeenenteredintheSTP correctiveactionprogramforcorrectioninfuturesubmittals.Thesigni"cantlyhighervelocitiesthatmayoccurwithsheeting"owatthebeginningofwashdownareinherentlyconsideredbytheassumptionthatall debrislandingonconcretewouldbewashedtolowercontainmentasdescribed inthefollowingquote.Tuesday1 stMarch,2016:19:32,Page303of393 DRAFTPART2.RAIRESPONSES(ROUND1)Section5.4ofreference23inLAREnclosure4-3statesDuringthewash-downphaseofaLOCA,debriswouldbetransporteddowntothecontainment poolbyoperationofthecontainmentspraysystem.Signi"cantamountsofde-briscould,however,becapturedontheconcrete"oorsandgratedareasabove thecontainment"oorascontainmentspraywatertransportingthedebrisdrains throughgratingtoreachthepool...However,forthisanalysis,itwasconserva-tivelyassumedthatalldebriswouldbewashedtolowercontainmentwiththe exceptionofanysmallandlargepiecedebrisheldupongratingasitiswashed down.2.3.6.12SSIB,Transport:Question7e STPResponse:(Item7e,Page68)Theobservationiscorrect,incorrectvaluesofFWGwereusedinSection5.a.3;the0.40and0.50shouldhavebeenreversed.Inotherwords,the0.50 shouldhavebeenimplementedinthe"rstequation(theequationwhichhasa solutionof0.19),andthe0.40shouldhavebeimplementedintheotherequation.

Also,inaccordwiththeequation,thecorrectde"nitionofFWGisfractionof debriswashedthroughthe"rstlevelofgrating.If40%ofdebrislandingon gratingiswasheddownthroughthegrating,then60%isheldup.Reference23 ofLAREncl.4-3wasrevisedtorevision3andcorrectedthis(1,Equation25 and26).Theresultingchangestototaldebristransportfractionsarediscussed intheresponsetoSSIBRAI6b,above.

References:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.13SSIB,Transport:Question7f STPResponse:(Item7f,Page68)Theleadingparagraphpertainsonlytowashdownfractions.ThediscrepancyhasbeenenteredintheSTPcorrectiveactionprogramfortrackingforcorrection infuturesubmittals.2.3.6.14SSIB,Transport:Question8a STPResponse:(Item8a,Page69)ThefollowingresponseisforSSIBRAI8athroughSSIBRAI8e.There-sponsepreviouslyprovidedinSection5.a.5(LAREnclosure5)wasnotimple-mented.CASAGrandeassumesnocreditforholdupofpartiallysubmerged debrisontheconcreteoftheoperatingdeck.Section5.a.5ofLAREnclosure5 wasaresponsetoNRCSComment/Question2.5.a.5inthe2013Submittal whichstates:Thebasisfortheproposedchangeisthattheresidualriskfromtheremain-ingGSI-191issues(e.g.,thosenotalreadyaddressedinadeterministicmanner) satis"esthecriteriainRegulatoryGuide(RG)1.174,Revision2,AnApproach ForUsingProbabilisticRiskAssessmentInRisk-InformedDecisionsonPlant-Tuesday1 stMarch,2016:19:32,Page304of393 DRAFTPART2.RAIRESPONSES(ROUND1)Speci"cChangestotheLicensingBasis,May2011(ADAMSAccessionNo.ML100910006).However,theapplicationdoesnotappeartoprovidest detailfortheNRCtodeterminewhetherthecriteriainRG1.174havebeen met.PleasedescribeindetailhowtheprinciplesofRG1.174criteriaregarding safetymargin,defense-in-depth(DID),andchangeinriskaremet.Inparticular, pleaseincludethefollowing:a.Regardingthetechnicalevaluationthatsupportstheriskmet-rics,theProjectSummary(Enclosure4totheapplication)describes numerousareaswherethetechnicalevaluationdeviatesfromtheap-provedguidanceforaddressingGS1191.However,theapplication provideslittleornoinformationonhowtheissueswereaddressed.

PleaseprovideadiscussionintdetailtopermitNRC reviewofthemethods,bases,assumptions,acceptancecriteria,and results.Iftestresultsareusedtodevelopprobabilitydistributions, pleasedescribehowthesedistributionsweredeterminedandusedin theoverallriskevaluation.Pleasealsoprovidethebasisfortheaccep-tancecriteriachosen.TheNRCrequiresadditionalinformation inthefollowingareas:5)TimedependenttransportThecorrectresponsetoquestion5.a.5istheonlytimedependenttransportthatoccursistheaccumulationofdebrisonthestrainers.2.3.6.15SSIB,Transport:Question8b STPResponse:(Item8b,Page69)SeeresponsetoSSIBRAI8a.2.3.6.16SSIB,Transport:Question8c STPResponse:(Item8c,Page69)SeeresponsetoSSIBRAI8a.2.3.6.17SSIB,Transport:Question8d STPResponse:(Item8d,Page69)SeeresponsetoSSIBRAI8a.2.3.6.18SSIB,Transport:Question8e STPResponse:(Item8e,Page69)SeeresponsetoSSIBRAI8a.2.3.6.19SSIB,Transport:Question10 STPResponse:(Item10,Page69)Thefailureandsubsequenttransportofunquali"edcoatingsissprayde-pendent(LAREnclosure4-3Reference12).Ifthereisnospray(spraysare secured),thereisnoadditionalfailedinventoryavailablefortransport.CASA Grandedoesnotincludeapredictivemodelofdebristransport,soconsidera-tionofadditionaltransportmechanismsmustbeincludedintheassignedfailure andtransportfactors.Thereareothertransportmechanismsbesideswashdown fromcontainmentspraysthatcouldcausefailedunquali"edcoatingsinventoryTuesday1 stMarch,2016:19:32,Page305of393 DRAFTPART2.RAIRESPONSES(ROUND1)totransport,suchasfreefallandcondensate"ow.However,noadditionalun-quali"edcoatingsareassumedtofailaftercontainmentspraysaresecured.The unquali"edcoatingsinventorypresumedfailed,computedastheproductofthe totalcoatingsinventoryandthetime-dependentfailurefraction(unquali"ed washdown),wasaddedtothecontainmentpoolwithinthe"rst10minutes(See theresponsetoESGB,CoatingsRAI4and5providedintheSTPlettertothe NRCSNOC-AE-00143103,datedMay22,2014,ML14149A434).Condensateonsurfacescouldpotentiallycarryparticlesofalreadyfailedunquali"edcoatingstothepoolaftercontainmentspraysaresecured.However, STPinputstoCASAGrandedonotassumetheadditionalfailureofunquali"ed coatingsonceContainmentSpraysaresecured,andnotime-dependentarrival wascredited.Theunquali"edcoatingsinventorythatfailed,computedasthe productofthetotalinventoryandthefailuretiming(unquali"edwashdown) fraction,wasaddedtothecontainmentpoolwithinthe"rst10minutes(See responsetoESGB,CoatingsRAI4).2.3.6.20SSIB,HeadLossandChemicalBumpUp:Question 14STPResponse:(Item14,Page70)Thecleanplantcriteriaisnotthebasisforusing1/16 thinchlimitforchem-icalbumpup.Any"berbuild-uplessthan1/16 thin.(thinbed)isunlikelytoloadcontigu-ously,allowingchemicalprecipitantstopassthroughthestrainermeshwithout causingasigni"canthead-lossincrease.Conventionalheadlossforbreaksthat donotformathinbedarecalculatedandevaluatedintheanalysis.Debrisbedsof1/16 thin.orthickeraresubjectedtochemicalhead-lossfactorsasdescribedinLAREnclosure4-3,Section5.6.3.Eachsimulatedbreakhasits owntime-dependentconventionalheadlossthatiscalculatedbasedondebris accumulationand"owrate,whichisthenaddedtoabaselineclean-strainer headlossof0.220ft-H20[1].Chemicalfactorsareappliedtotheconventional headlosswhenthetemperatureislessthan140

+/-5Fandthe"berloadexceeds 1/16 thin.equivalentthickness.AsensitivityanalysiswasperformedinCASAGrandebyapplyingthechem-icalbump-upfactortoathinbedthresholdvalueof0in.toassessthee ofthatvariableusingthemaximumamountofconservatism.Thissensitivity analysisshowednoeonTherefore,usingachemicalmultiplieron anythinglessthan1/16 thin.wouldnotin"uencerisk.AfurthersensitivitystudyindicatesthatthemultiplierontheMBLOCAconditionmustbehigherthan60 toincreasetheriskassignedbyCASAGrandeCase01(allequipmentoperates).

TheSBLOCAheadlossfactorinthissensitivity,althoughhigherthanassumed intheLAR,doesnotin"uencetheriskbecausenoneoftheSBLOCAscenarios formathinbed.

References:

1.66-9088089-000.SouthTexasProjectTestReportforECCSStrainerTest-ing.Revision0:August29,20082.SteamGeneratorTubeIntegrityandChemicalEngineeringBranch.RAIESGB-1-5Revision0Tuesday1 stMarch,2016:19:32,Page306of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.21SSIB,HeadLossandChemicalBumpUp:Question 15aSTPResponse:(Item15a,Page71)Correlationsareimportantforcapturingsubtletrendsandinteractionsbe-tweenphysicalvariablesincludingcombinationsofdebrisloadsand morphologies.Strainerquali"cationtests,likewise,donottestallpossiblede-brisloadsandmorphologiespresentunderplantconditions.However,incombi-nation,correlationshelpidentifycombinationsofconcern,especiallyacrossthe fullspectrumofRIanalysis,andstrainertestsprovideproofofperformancefor themostchallengingconditionsidenti"ed.Predictionsofheadlossandcon"r-matorystrainertestingprovidecomplementaryandessentialelementsforfull understandingofstrainer-relatedECCSfailure.OtherRAIresponsesaddress moredirectlytheissueofvalidationoverappropriaterangesofplantconditions.2.3.6.22SSIB,HeadLossandChemicalBumpUp:Question 15bSTPResponse:(Item15b,Page71)Lateralinhomogeneity(acrossthefaceofastrainersurface)isalwayspre-sumedtocauselesstotalheadlossthanacontiguousuniformbedofthesame composition.Lateralinhomogeneityiscommonlyobservedinstrainermodule testingwhereitcanbedtoformacontiguousbedthatleadstomaxi-mumobservedpressuredrop.STPagreesthatlateralinhomogeneityislikelyto occurandwillreducetheactualheadlossthatoccurscomparedtothemaximum headlosspredictedbycorrelation.Inhomogeneouscompositionthroughthethicknessofthebedmayexistthatelevatetheobservedheadloss.Twoexamplesofpotentialconcernare(1)chem-icalproductsarrivinginbulkatthetopofapre-establishedbed,and(2)im-pactionof"nelydivideddebrisintheholesofthestrainerplatecausingalocal reductioninporosity.Bothconditionsareinvestigatedinthesupplementary report(Enclosure1).Althoughnoevidenceofbulkchemicalprecipitationpo-tentialhasbeenobservedforSTP,simulationsofathinlayeroflowporosity, high-S vdebrisatthetopofthebedshowafactorof2increaseinheadlosscom-paredtothesamemassofmaterialdistributedthroughoutthebed(Enclosure 1).Localimpactionof"berinthestrainerplateholeswasobservedintheCHLE-10UNMtestwhichused"berpreprocessedinablender.Theteststartedthe introductionofchemicalsat6.75dayswithamaximum1400%increaseinhead losscomparedtothe1-daysteadystatevalue(LAREncl.4-3,Ref.[17]).Calcula-tionsshowcomparablepotentialhead-lossincreasewhenporosityinthestrainer plateori"ceisgreatlyreduced.Largequantitiesofextremelysmall"bershards (brokenglassstrands)arenotexpectedtobeproducedintheLOCAZOIenvi-ronment,andarenotincludedaspartofthemodi"edNEIdebris-preparation protocol.2.3.6.23SSIB,HeadLossandChemicalBumpUp:Question 15cSTPResponse:(Item15c,Page71)STPhasonlyonestrainercon"gurationthatisconsistentforall3trains.Tuesday1 stMarch,2016:19:32,Page307of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThePCIdesignwascon"rmedbytestingtoloaduniformlyacrossthefaceofthestrainersurfacearea,sothepotentialforgeometricvariationsatSTPisgreatly

minimized.Maximum"owvelocitiesof0.0086ft/satSTParenotwithintheHTVLtestrange,butlowvelocitiesarerepresentedintheARL"umetestsandintheUNM verticalcolumntests,whichareavailableforvalidationoftheNUREG/CR-6224 correlationthatwasimplementedfortheLAR.Thesupplementaryreportac-companyingthisresponse(Enclosure1)providesameansformorerobustcor-relationof"owconditionsintermsofReynoldsnumberthatencompassesve-locity,waterproperties,andbedparametersofporosityandsurface-to-volume ratio.Theproposedcorrelationillustratesthatexistingtestsusedtovalidate NUREG/CR-6224exposethebedtoamuchwiderrangeof"owconditions(two ordersofmagnitude)thanpreviouslythought.Theexpandedrangeofcondi-tionssupportsapplicabilityforRIuseofacorrelationprovidedthatacceptable comparisonstotestdatacanbeachieved.Reynoldsnumberforinternal"owthroughadebrisbedisde"nedas, Re= Aµ(1m)S v (1)whereis"uiddensity,µis"uidviscosity, w A,isstrainerapproachvelocity,m,ismixtureporosity,and S vissurface-to-volumeratioforthesoliddebris.Theseattributescanbedeterminedindependentlyofanypresumedhead-losscorrelationforanyhomogeneousmixtureofdebris.DistributionsofReynoldsnumberwerecompiledfromCASAGrandeanaly-sisconditionedonLOCAcategoryforbedcon"gurationsand"owratesexisting attheendofeachbreakscenario.Whenthesludgecompactionlimitisnot enforced,expectedvalues(means)andmaximaofReynoldsnumberforeach LOCAcategoryareBreakSizeSmallMediumLargeAvg.Reynolds#0.02370.080.3105 MaxReynolds#0.07480.25651.748ThecumulativedistributionofReynoldsnumberforlargebreakscenariosisillustratedinFig.A,whichshowsaverynarrowrangeofinterest.Manycombi-nationsofEq.(1)parametersleadtosimilar"owregimesasde"nedbyReynolds number.Thesupplementaryreport(Enclosure1)proposesarobustcorrelation basedonanexplicitrepresentationofReynoldsnumberanddemonstratesthat typicalHTVLtestingdoesinfactspan(andlikelyexceeds)the"owregimesof interestforSTP"owconditions.Giventheadequateoverlapof"owconditions tested,discrepanciesbetweenblindpredictionsofacalibratedmodelandHTVL testdatacanbeattributedtotbedcompressiondescriptionsandto localstrati"cationthatthespatialdistributionofporosityandsurface area-to-volumeratio.Insummary,velocityisonlyonefactorthatcontributesto"owregimeinacompositedebrisbed,butmanyfactorsinteractasshowninEq.(1).When allotherfactorsareequalexceptvelocity,conventionalinterpretationsofhead-losscorrelationsindicatethatlowervelocityleadstolowerheadloss,lessbedTuesday1 stMarch,2016:19:32,Page308of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:CumulativeprobabilitydistributionforReynoldsnumberexperiencedunderlarge-breakscenarios.compression,andslowermigrationofparticulates.Therefore,sincecomparableReynolds"owconditionshavebeenachievedintheteststhroughacombination offactors,itisreasonabletoexpectthatlowerpressuredropswouldhavebeen observedwhentestingatlowervelocitiesidenticallymatchingplantconditions.

Reynoldssimilitudeextendstotheplantcon"guration,sothecurrentsuiteof testconditionscanbeconsideredadequateforvalidation.2.3.6.24SSIB,HeadLossandChemicalBumpUp:Question 15dSTPResponse:(Item15d,Page71)PrincipaluncertaintiesexistinthedragareaparameterSv(solidsurface-to-volumeratio)andinthebedporosity.ConclusionsoftheSTPLARarenot becauseuncertaintyinmaterialpropertiesiscompensatedbythefactor of5uncertaintyboundandbecauseintendedapplicationofabedcompaction limitobviatesconcernsregardinglocalporosity.Thesupplementaryreport(Enclosure1)providedwiththeSSIBRAIre-sponsesusesdirectmeasurementofsurface-to-volumeratiotominimizeuncer-taintiesindebrisproperties.Forthecalibrationtest,measuredvaluesofSvare approximately250%lessforacrylicpaintdebris,whichisasurrogateforqual-i"edepoxy,thanthestandardgeometricapproximationforquali"edepoxyin LAREnclosure4-3.High-"delityreproductionsofthetestdataareobtained usingmeasuredSvwhenbedcompressionisallowedtoequilibratewithpressure dropandnocreditistakenforrelaxation(thicknessrecovery)afterexposureto hightialpressure.Bycomparison,applicationofNUREG/CR-6224with afactorof5uncertaintyboundconsistentlyoverpredictsalltestmeasurements.Formulasformixtureporosityarewelldevelopedbetweenthephysicallimitsofsludgecompactionandtheoreticalporosityofclean"ber.Uncertaintiesinbed porosityarethereforelargelycausedbyuncertaintiesinpotentiallocalstrati"-

cation,whichisaddressedintheresponsetoSSIBRAI15b,andbyperformanceTuesday1 stMarch,2016:19:32,Page309of393 DRAFTPART2.RAIRESPONSES(ROUND1)ofthebedcompressionmodel.TheSTPanalysisintendedtoapplythesludgecompactionlimitthroughoutthebedofhomogeneouslymixedcompositionto minimizetheoftheseuncertainties.(Note:correctimplementationofthe sludgelimitassumptionwillleadtoanincreaseinResponsestoSSIB RAI18band18cprovidefurtherdetail.)2.3.6.25SSIB,HeadLossandChemicalBumpUp:Question 16aSTPResponse:(Item16a,Page71)VerticallooptestsconductedbySTPareimportanttodemonstratethecon-clusionthattheSTPLARapproachforpredictivehead-lossestimation,which includesanintendedsludgecompactionlimitandafactorof5uncertaintybound appliedtotheNUREG/CR-6224model,adequatelyenvelopesvariabilitynoted bythebetweentfacilitiesundersimilarconditions.Itisnoted,how-ever,thatimportantddoexistbetweenteststhatareoftendescribed assimilar.Forexample,whileHTVLSeries2Test8emulatesastrainertest withrespecttodebrisquantityand"owconditions,debrispreparationwassub-stantiallyt;theHTVLtestusedNEIprepareddebrisandtheARLtest usedblenderprocesseddebris.VerticallooptestsconductedbySTParevalidtotheextentthattheyrepro-duce"owconditionsinrepresentativedebriscon"gurationssothattheaggregate head-lossapproachcanbedemonstratedtoboundprototypicalconditions.The approachappliedintheSTPLARboundsalltotalhead-lossmeasurements takeninprototypicaltestconditions.Whileitisdesirabletohaveapredictive approachthatcanreproducealltestconditionswithhigh"delity,uncertainties inbedcon"gurationanddebrischaracteristicscandominatethecomparisonof replicatetestsandnumericalsimulations.HTVLtestsweredesignedtorepresent themostprevalentconditionsexpected,andsuccessfulcomparisonoftheSTP LARcalculationmethodto"umetestdata,asdemonstratedintheresponseto ESGB,ChemicalRAI2,provideshighcon"dencethatunderprediction willnotskewtheriskquanti"cation.Deterministicperspectivesrelatedtothede"nitionofaworst,ormostchal-lenging,setofconditionshavelongdominatedassessmentoftestvalidityand acceptability.Therisk-informedperspectivecombinesthatinterestinchalleng-ingconditionswiththeirfrequencyofoccurrence,sothatjudgmentoftestva-liditycannowincludeabroaderinterpretationofapplicabilitytoplant-speci"c conditions.ThesupplementarywhitepaperprovidedwithSSIBRAIresponses (Enclosure1)explainsanewperspectiveonhead-losscorrelationbasedon Reynoldsnumberforinternal"ow.AdistributionofReynoldsnumberwasextractedfromtheCASAGrandeanalysisspectrumforalllargebreakhistoriesinatypicalstatisticalreplicate.

AsshownintheresponsetoSSIBRAI15cand17c,typicalinternalReynolds numbersforaLBLOCAvarybetween0.1and1whenthesludgecompaction limitisnotenforced.STPverticalcolumntestswereusedtocalibratethenew modeloveranadequaterangeofReynoldsnumberspanningfrom0.2to4.5.The newcorrelationshowsthatexistingverticalhead-losstestsbroadlyrepresentthe rangeneededforpredictionsintheRIapplication.Thesupplementaryreportfurtherdemonstratesthatthealternativehead-Tuesday1 stMarch,2016:19:32,Page310of393 DRAFTPART2.RAIRESPONSES(ROUND1)losscorrelationisconsistentwithtestdataandproducespredictedhead-lossvalueswellbelowthoseproducedbytheNUREG/CR-6224correlationasimple-mentedintheLAR.Recallthatthesludgelimitforbedcompactionisintended asaconstraintonminimumbedporosityandthatafactorof5isappliedto coveruncertaintiesinbedproperties,correlation"delity,andtestingvariability betweenfacilities.2.3.6.26SSIB,HeadLossandChemicalBumpUp:Question 16bSTPResponse:(Item16b,Page72)VerticallooptestsareimportanttoconclusionsintheSTPLARonlytotheextentthattheycorroboratetheconclusionthathead-losspredictionsmadefor uniformcontiguousbedsshouldboundactualstrainerperformanceforsimilar totaldebrisloadsand"owconditions.Verticaltestresultsalonearenotintended asexclusiveprotectionofthisassumption.Thefactorof5uncertaintyappliedto theNUREG/CR-6224head-losspredictionsalsohelpstoensurethisassumption.

SeetheresponsestoSSIBRAI16aandSSIBRAI28foradditionaldiscussion ofthisstrategy.Verticallooptestsconductedundersite-speci"cconditionsshouldcorrelateto"umetestsconductedundersimilarconditionsandtoheadlossesthatoccurin theplanttotheextentthatmoredebrisand/orhighervelocity,and/orreduced porosityallproducehigherheadlossinalltestcon"gurations.However,HTVL Test8,anintendedreplicateoftheARL"umetest,resultedinamuchlower headlossatacomparabletemperatureanda"owrateapproximately2.5times higherthanthe"umetest.Manydisparitiesinthetestconditionsincluding debrispreparationcontributedtothisdiscrepancy.Inthisapplication,correlationdoesnotimplyaneedforperfectagree-mentbetweenmodelandtests.Conclusionsintheapplicationareconstructed aroundlimitingassumptionsthatcompensateforknownde"cienciesinthe NUREG/CR-6224head-lossprediction,oneofthemostnotablede"cienciesbe-ingthebedcompressionresponseformixeddebriscomposition.Debristransportedbyassumptiontothehorizontalstrainersurfacewouldresultinadebrisbedcomposedof"neandsmall"bersizesloadedwith100%of particulatereachingthepool.Allmaterialsareassumedtobefullytransportable withtheambient"owvelocity,whichfurtherconsistencywithactualplant transportofsmalland"nematerial.Theassumptionofmaximumcompression shouldresultinhead-losstrendsthatarehigherthanmeasuredinthevertical loop.Verticalhead-losstestsincombinationwithassumptionsimplementedwith theresultingcorrelationprovidecon"dencethathead-losstrendsarereasonably (butnotunduly)conservativewithrespecttoactualplantstrainerperformance.Headlossobservedinverticaltestingandinstrainertestingisdrivenby"owconditionswithinthedebrisbedandnotbytheactualconstituentsof thedebris.Thissimilitudeisthebasisforsubstitutionofparticulateshaving similarsizedistributions.Therefore,headlosseswillbecomparableforsimi-lar"owconditionsde"nedby:velocity,"uidproperties,porosityanddragarea

(S v).Thesupplementaryreport(Enclosure1)accompanyingtheseSSIBRAIresponsesfurtheremphasizestheimportanceofrobustcorrelationbasedonin-ternal"owconditions.ResponsestoSSIBRAIs15c,17c,and16adiscussrangesTuesday1 stMarch,2016:19:32,Page311of393 DRAFTPART2.RAIRESPONSES(ROUND1)ofReynoldsnumbercoveredbytestingandbythespectrumofbreakscoveredinCASAGrande.Bedmorphologyintheformofalternatediscretestrati"cation isaddressedintheresponsetotheSSIBRAI15b.Intotal,thesecomparisons demonstratethattheLARapproachtohead-losspredictionwillreproducethe properbehaviorwithrespectto"owrate,debrisloadandtemperature,while overestimatingactualstrainerperformanceundersimilarconditions.2.3.6.27SSIB,HeadLossandChemicalBumpUp:Question 16cSTPResponse:(Item16c,Page72)ThepurposeofusingapredictivecorrelationintheSTPLARistorepro-duceobservedtrendsinheadlossasafunctionofdebriscompositionand"ow conditionssothatcrediblesensitivitystudiescanbeperformedtodetermine drivingfactorsandsubtleinteractionsthathavenotbeenanticipatedpriorto theRIclosurepilotstudy.Implementationofthecorrelation,includingsludge-limitcompactionandafactorof5uncertaintybound,isdesignedtoprovide con"dencethatpredictionsboundrealisticstrainerperformanceforthemajor-ityofdebriscombinationsand"owconditionsthatareexperiencedintheplant.

Noneofthesegoalsrequireexactagreementbetweentestconditionsandcorre-lation.Infact,thecorrelationutilizedintheverticalhead-losstestreportdid notincludethesamehead-lossassumptionsusedinthe"nalimplementation.Forexample,theresponsetoESGB,ChemicalRAI2citescompar-isonsofmaximumhead-lossvaluesobservedin"umetestingplacedincontextas percentilesofallhead-losspredictionsobtainedfromtheCase01(allequipment operates)CASAGrandeanalyses(whichincludethefactorof5uncertainty, butnotthefulleofsludge-limitcompaction).Measuredmaximaliewithin theenvelopeofcomputedmaxima(evenwithoutthefulleofsludge-limit compaction),andpredictedmaximaliewellabovethestrainer-collapsethresh-oldof9.35ft.NoneoftheARL"umetestsmeasuredheadlossexceedingthe strainerbucklinglimit.Thesecomparisonsprovideassurancethatthecorrela-tionasimplementedservesitsdualroleoftrackingtheinteractionofcomplex debrisbehaviorandprovidingreasonablyconservativeboundsonactualstrainer performance.2.3.6.28SSIB,HeadLossandChemicalBumpUp:Question 16dSTPResponse:(Item16d,Page72)AsimplementedintheLARwithacodelevelerrorthatrevertedallcasestomixed-bedporositywithoutcompression(describedintheresponsestoSSIB-RAI18band18c),andafactorof5uncertaintybound,theNUREG/CR-6224 correlationpredictionsboundthemeasuredmaximumheadlossesreportedfor theFebruary(1)andJuly(2)2008tests.TheoneexceptionisFebruaryTest 3thatwasdeterminedtobenon-representative.ResponsetoESGB,Chemical RAI2citescomparisonsofmaximumhead-lossvaluesobservedin"ume testingplacedincontextaspercentilesofallhead-losspredictionsobtainedfrom Case01(allequipmentoperates)CASAGrandeanalyses(whichincludethe factorof5uncertainty,butnotthefulleofsludge-limitcompaction).DBA testsarewellabovethe95thpercentileofallsimulatedbreaksandyetwellbelowTuesday1 stMarch,2016:19:32,Page312of393 DRAFTPART2.RAIRESPONSES(ROUND1)predictedmaximathatincludechemicalOnecriticismoftheSTP"umetestshasbeenpossibleunderestimationof"berdebrisvolume,andonepossiblede"ciencyofthepredictivemodelisim-propersludgecompaction.Distributionsofpredictedhead-lossincludedebris volumesconsistentwith17DZOIthatareassumedforNukon"berglass,and atleastonetestincluded"bervolumesthatarecomparabletothisinventory (FebruaryTest4).Increasedpredictedheadlosswillbeexperiencedwhenthe sludge-compactionlimitisproperlyimplemented(possiblybyafactorof2),

sopredictedmaximawillincreaseevenasmeasuredheadlosswouldincrease if"berdebrisvolumeswereincreasedforstrainertesting.Giventhehighper-centilesofDBAtestingwithrespecttothesimulations,itisunlikelythatmore stringenttestconditionswouldchangetheconclusionthatcurrentapplicationof theNUREG/CR-6224correlationprovidesanacceptableenvelopeforpotential headlossacrosstheECCSstrainer.

References:

1.0415-0100069WN/0415-0200069WN,SouthTexasProjectTestReportforECCSStrainerPerformanceTestingFeb2008,RevisionA,11/24/2008.2.0415-0100071WN/0415-0200071WN,SouthTexasProjectTestReportforECCSStrainerPerformanceTestingJuly2008,RevisionA,11/24/2008.2.3.6.29SSIB,HeadLossandChemicalBumpUp:Question 17aSTPResponse:(Item17a,Page73)TheLARisnotattemptingtoapplythecorrelationalonetoqualifyper-formanceofaparticularstrainer,butrather,isusingthecorrelationtoreveal trendsinstrainerperformancethatmaychallengeriskinformedsuccesscriteria.

Thecorrelationaloneisonlyonepartoftheapplication.Theassumptionof fullbedcompressionanduncertaintyfactorof5mustalsobeconsideredpart ofthehead-losspredictionthatcompensatesinpartforsomeofthe complicationswithNUREG/CR-6224.AsnotedinthisRAI,theNUREG/CR-6224correlationhasnotperformedwellformicroporousdebris.However,STPhasasparseamountofmicroporous debristhatdoesnotdominatetheheadlossbehaviorortherisk.Theabsence ofmicroporousdebrisinvalidationtestingisconsistentwithplant-speci"ccon-

ditions.HTVLtestseries2(LAREnclosure4-3,Reference[24])attemptedtorepli-cateARL"umetestingofSTPstrainers(1)usingplant-speci"cdebriscombina-tionsof"berglass,tin,acrylicpowderandchips,Microtherm,MarinateBoard, andlatentdirt/dust.AtSTP,"berglassandunquali"edepoxycoatingsthatare presumedtofailrepresentthedominantconventionaldebristypes.OthertestsintheHTVLtestseries(LAREnclosure4-3,Reference[24])employedalong-standingpracticeofusingsubstituteparticulates.Forexample, acrylicpaintpowderwasusedasasubstituteforfailedepoxycoatingsandsilicon carbidewasusedtorepresentlatentdebris.Substitutionofparticulatesshouldbeacceptableaslongas"owconditionsinternaltothebedcanbeestablishedthatareplantspeci"c.Analternatehead-lossmodelbasedoncorrelationof"owresistancetoReynoldsnumber(Enclosure 1)wascalibratedusingexistingHTVLtestdata.ComparisonofReynolds"owTuesday1 stMarch,2016:19:32,Page313of393 DRAFTPART2.RAIRESPONSES(ROUND1)regimesachievedinthetests(0.2to4.5)to"owregimesextractedfromthepopulationofCASAGrandebedcon"gurationsshowsverygoodagreement.

Additionaldetailofthis"ow-regimecomparisonisprovidedintheresponsesto SSIBRAI15cand17c.

References:

1.0415-0100071WN/0415-0200071WN,SouthTexasProjectTestReportforECCSStrainerTestingJuly2008,RevA,11/24/2008.2.3.6.30SSIB,HeadLossandChemicalBumpUp:Question 17bSTPResponse:(Item17b,Page73)TheUNMverticallooptestingisconsideredtobepartoftheNUREG/CR-6224validationwhichincludedawiderangeofdebrissizesincluding blender-processed"berglass.HTVLtestingconductedatAlionHydraulicsLab-oratoryusedamodi"edNEIdebrispreparation.Therefore,prototypicaldebris sizesareconsideredtobewellrepresented.AsmentionedintheresponsetoSSIBRAI15cexaminationofReynolds"owconditionsshowsthatregimesofinterestidenti"edintheCASAGrandeanalysis spectrumarewellrepresentedbyexistingtestdata.2.3.6.31SSIB,HeadLossandChemicalBumpUp:Question 17cSTPResponse:(Item17c,Page73)SeetheresponsetoSSIBRAI15c.2.3.6.32SSIB,HeadLossandChemicalBumpUp:Question 17dSTPResponse:(Item17d,Page73)Forthepurposeoftherisk-informedLAR,validationtestingincludes:(1)strainertesting,(2)HTVLtesting,and(3)UNMverticalcolumntesting.Strainer testingdidincludeprototypicalSTPgeometry,andoneseriesofHTVLtestswas patternedafterthe"umetestconditions,debristypesanddebrisloading(LAR Enclosure4-3,Reference[24]).2.3.6.33SSIB,HeadLossandChemicalBumpUp:Question 17eSTPResponse:(Item17e,Page73)Forthepurposeoftherisk-informedLAR,validationtestingincludes:(1)strainertesting,(2)HTVLtesting,and(3)UNMverticalcolumntesting.Strainer testingdidincludeprototypicalgeometriesusedatSTP.Whiletruethatvertical looptestingdoesnotincludeallgeometriceconsistentlyuniformdebris bedsaretoformevenundercontrolledtestconditions.Occlusionsand bridgingoftenobservedinstrainerteststendtoadmitmore"owperunitarea andreduceheadloss.Thisisanimportantreasonforconductingcorrelation testingunderverticalloopconditions.Currentstrainertestproceduresemphasize100%debrisloading,soalldebrissizespresentinNEI-preparedtestmaterialisequallyrepresentedinboththe strainerandverticalcolumntestcon"gurations.Small"bermaterialconsistent withNEIdebrispreparationmethodsissimilarlytransportableasthe"nes.Tuesday1 stMarch,2016:19:32,Page314of393 DRAFTPART2.RAIRESPONSES(ROUND1)Ingeneral,uniformbedsconstructedinverticalcolumncon"gurationspro-videamoreconsistentbasisforvalidationandmoreconservativeresultswhen allbedparametersareequal,somorevalidationanalysishasbeendevotedto thesetestconditions.2.3.6.34SSIB,HeadLossandChemicalBumpUp:Question 17fSTPResponse:(Item17f,Page73)Consistentwiththisobservation,con"rmatoryanalysisisprimarilyfocusedonrecentdatasince2010withtdocumentationtodemonstrateappli-cabilitytoplantconditions.ThesupplementaryreportaccompanyingthisRAI response(Enclosure1)presentsanalternativehead-losscorrelationtoprovide perspectiveontheuseofNUREG/CR-6224asimplementedintheLAR.The newmodelhasbeencalibratedandveri"edusingrecenttestdata.2.3.6.35SSIB,HeadLossandChemicalBumpUp:Question 18aSTPResponse:(Item18a,Page73)TheresponsetoSSIBRAI11cprovidesjusti"cationofawell-mixedcon-tainmentpoolandstates,"1.Forallbreaks,theinitialhigh"oorvelocitiesfrom sheeting"owcausedbythepipebreakandcontainmentspraysareexpectedto scatterdebriswithnopreferentialdirectionthroughoutcontainment.2.Finede-briswillbefurthermixedafterrecirculationbecauseofmultidirectionalvelocity vectorsandturbulentkineticenergy."Ahomogeneouslymixedcontainmentpool supportsformationofahomogenousdebrisbed.Also,theassumptionofearly andnearlysimultaneousdebrissourceintroductionfurthersupportsformation ofahomogenousdebrisbed.Oncedebrisarrivesatthestrainer,migrationprocessestendtohomogenizeanystratathatmightinitiallybeformedbysequentialarrival.Particulatemi-grationisclearlyevidentinalltestcon"gurationsasvisiblecloudsofparticulate orchemicalsthatpassthroughthedebris.Whenvisibilityinaverticalcolumn testimprovesthroughcontinued"ltration,itissometimespossibletoobserve particulatemigrationthroughtheedgesofthedebrismat.2.3.6.36SSIB,HeadLossandChemicalBumpUp:Question 18b STP Response:(Item18b,Page315)Toclarifytheimplementationofmanufactureddensity,thevelocityandcom-pressionmodelsmustbeexplainedinfurtherdetail.Thetime-dependentvelocity usedtoevaluatethehead-losscorrelationwasdeterminedbydividingthevolu-metric"owratebythesurfaceareaofanuncompressedbedwithanassumed densityof2.4lb/ft3.Thisassumptioncausesanearliertransitiontothecircum-scribedareaforlargebreakshavingenoughdebristo"llinterstitialstrainergaps thataremostlikelytochallengeplantperformancecriteria.Transitiontocir-cumscribedareacancauseasuddenincreaseinfacevelocityandacorresponding increaseinheadloss.Theintendedtreatmentofbedcompressionwastoevaluateallcaseswithaminimumporosityandminimumbedthicknessde"nedbyamaximumpackingTuesday1 stMarch,2016:19:32,Page315of393 DRAFTPART2.RAIRESPONSES(ROUND1)densityof65lb/ft3.Thisapproachisindependentfromtheassumptionusedtocalculatefacevelocity.Thecurrentquanti"cationdoesnotincludeofthe intendedcompressionlimit.Assuggested,asensitivitytestwasperformedusing thesludgelimitasaplausiblecompressionconditionthatresultedina increasebyafactorof1.8.Thebedcompressioncalculationisbeingrevisedasshownbelow:

Forverylargepressuregradients,thecompressionhastobelimitedsuchthatamaximumsolidityisnotexceeded.InNUREG/CR-6224,thismaximum solidityisde"nedtobe:m=65lbm/ft 3p(Equation38a)Thisisequivalenttohavingadebrislayerwithadensityof65lbm/ft3.Notethat65lbm/ft3isthemacroscopic,orbulkdensityofagranularmediasuchas sandorgravelandclay.Formixed"berandparticulatebeds,thesludgepackingdensityisconsideredtobeconservativelyhighandtheanalogoussoliditylimitis:m=V p+V f V bed=m ff+m pp65lbm/ft 3 m f+m p(Equation38b)wherethesubscriptsreferto:

f,"ber p,particulate and Visthevolume, misthemass, V x=solid"bervolume(f),solidparticulatevolume(p),totalbedvolume(bed), m x="bermass(f),particulatemass(p),x=average"berdensity(f)oraverageparticulatedensity(p).Toavoiditerativesolutionsimpliedbythe"bercompressionformulasthatbothanddependontheheadloss,thehighparticle-to-"berratiolimitfor mixedbedsoliditywasappliedtoallhead-losscalculations.Thecorresponding limitingbedthicknessisfoundbysubstitutingEq.(36)intoEq.(35)andsolving forbedthicknessusingEq.(38b)asthelimitingmixed-bedsolidity;L m=1m1+fp0L 0(Equation38c)2.3.6.37SSIB,HeadLossandChemicalBumpUp:Question 18cSTPResponse:(Item18c,Page73)Presentquanti"cationoftheSTPLARintendedtoimposesludge-limitpack-ingdensityforallcasestoavoiditerativerequirementsoftheNUREG/CR-6224compressionmodel.However,acode-levellogicerrorrevertedallcasesto mixed-bedporositywithoutcompression.Implementationofthesludgelimitas intendedincreasesbyafactorof1.8withallotherinputsequivalentto thebaseline.TheresponseprovidedtoRAISSIB-RAI-18bdescribeshowthe sludgelimitiscalculatedandapplied.TheconditionhasbeenenteredintheSTPcorrectiveactionprogramandtheAlioncorrectiveactionprogram.Tuesday1 stMarch,2016:19:32,Page316of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.38SSIB,HeadLossandChemicalBumpUp:Question 18dSTPResponse:(Item18d,Page74)Thesupplementaryreportpreparedtoaccompanyhead-lossRAIresponses(Enclosure1)illustratesthatlinearvolumeweightingisthepropergeneral treatmentforcompositeaveragingofsurface-to-volumeratio.Massandvolume weightinggiveidenticalresultsintheidealcasewherealldebrisdensitiesare identical.Comparisoncalculationsbetweenthetwomethodsshownosigni"cant increaseinwhenlinearvolumeweightingisappliedwithSTP-speci"c

inputs.2.3.6.39SSIB,HeadLossandChemicalBumpUp:Question 18eSTPResponse:(Item18e,Page74)Packingfractionisdrivenbythegeometryofparticles.Theassumptionthatallcoatingmaterialshaveasimilarpackingfractiontoacryliccoatings(0.39 asdescribedinSTPLAREnclosure4-3,Reference24)isreasonablebecause theconstituentsarecomparableinsize,approximately10microns.Non-coating particulatedebriswasassumedtohaveapackingfractionsimilartoironoxide sludge(0.20).NUREG/CR-6224citesthepackeddensityofironoxidesludgeas 65lb/ft3.PerMarksEngineeringHandbook(1),awetmixtureofclayandsoil alsohasadensityof65lb/ft3.Packingratiosforcoatingsmaterialsarenotuseddirectlyinthehead-losscalculation,sothereisnomeasurableofthisassumptiononresults.Limitedinformationisavailableforpackingratiosofpurecoatingsmaterials,whichiswhydegradedcoatingswereassumedtohavepropertiessimilarto acryliccoatingsthataredescribedinSTPLAREnclosure4-3,Reference24.

Reference:

1.Avallone,E.andTheodore,B.MarksStandardHandbookforMechanicalEngineers.McGraw-HillCompanies,Inc,1999.2.3.6.40SSIB,HeadLossandChemicalBumpUp:Question 19STPResponse:(Item19,Page74)ThehasnotednumeroussensitivitiesoftheNUREG/CR-6224head-losscorrelationtomaterialpropertiesanddebriscon"gurationswithintheporous bed.Residualuncertaintyalsoexistsindataavailabletodescribeproperties andbedcon"gurations.Sensitivitiesanduncertaintiesmayexistregardlessofthe "delityofthepredictivemodel,soitisappropriatetoacknowledgethepossibility ofhigherhead-lossthanindicatedbytheexistingmodel.Thefactorof5(with astandarddeviationof1)isappliedtorepresentpropagationofuncertainty andmodelingsensitivities.STPdoesnotviewthissimplyasasafetyfactor,but ratherasasurrogateenvelopeonvariabilitynotfullyresolvedbythemodel.

STPapplicationoftheNUREG/CR-6224correlationincludestheassumptionof sludge-limitcompactionandthefactorof5uncertaintyenvelope.Whileisolated conditionsmayexistthatcauseNUREG/CR-6224alonetounderestimateheadlossbymorethanafactorof5,itisnotclearthatthoseobservationsincludetheassumptionofsludgecompaction,northeuseofrepresentativedebrismaterial.Tuesday1 stMarch,2016:19:32,Page317of393 DRAFTPART2.RAIRESPONSES(ROUND1)AnalternativecorrelationbasedonReynoldsnumberintheviscoustoinertialsheartransition(VISTA)developedinasupplementaryreport(Enclosure1) illustratesthattheLARassumptionsareconservativeforthepredominant"ow conditionsofinterest.ThestrategyusedtoassureadequacyofSTPLARhead-losspredictionsincludesthreeparts:1)Supplementaryreport(Enclosure1)demonstratestestresultscanbere-producedwithgood"delityusinganindependentphysicalmodelthat addressesknownde"cienciesoftheNUREG/CR-6224correlation,2)Supplementaryreport(Enclosure1)demonstratesavailabletestconditionsspan"owregimesofinterestforSTPandthatrealisticmodelsreproduce themostprevalentconditionswiththehighestaccuracy,3)ResponsetoESGB,ChemicalRAI2demonstratestheLARap-plicationreasonablyboundsavailabletestdata.2.3.6.41SSIB,HeadLossandChemicalBumpUp:Question 20STPResponse:(Item20,Page74)Largemiscellaneousdebris(tags,labels,ties)istreatedbystandardmethodsasadirectreductioninstrainerarea.IntheLAR,paintchipsarecategorizedbystandardsizesandinventoriesforeachsizearedeterminedbyexternalanalysisofboundingbreakconditions.

Largechipsandcurlstypicaloffailedunquali"edcoatingsarenotpresentduring "ll-uptransportandhaveverylowtransportfractionsunderSTPrecirculation conditions,sotheyarenotexpectedtoobstruct"owthroughindividualstrainer openings.Whenlargeparticles(greaterthan10umlargestdimension)arepresentinacompositedebrisbed,they"uid"owthroughtheirtotaldragareajust likeanyotherdebriselement.Althoughbedscomposedentirelyof"akesand chipsorientedperpendiculartothe"owmayhaveauniquebehavior,thereisno reasontosuspectthatrandomlyorientedchipsand"akescannotbemodeledby standardcorrelations.Infact,becauseaveragesurface-to-volumeratiosforlarger debriselementsaresmallcomparedtoverysmallparticulates,thecontribution oflargeparticlesandchipsisoftenignoredintestcon"gurations.ThereisnointentinLAREnclosure4-3,Section5.6.2totreatchipsand"akesassphericalparticles.Whentheoriginalquanti"cationwasperformed, CASAGrandeonlyincludedgeometricsurface-to-volumeratioformulasfor spheres(particulatewhere S sph V=6/dforparticlediameter d)andforforcylin-ders("berswhere S cal V=4/dforparticlediameter d).Inthematerialpropertiestable,arti"cialsphericaldiameterswereintroducedforpaintchipstoensure thatthedesiredsurface-to-volumeratioforchips(S chip V=2 tforthickness t)werepreserved.Equivalentsphericaldiameteriscomputedas d=2 t.Thisisanunnecessarycomplicationoriginallyintroducedforexpediency,butitdoesnot changethefundamentaltreatmentofpaintchipsinthehead-lossevaluation.Tuesday1 stMarch,2016:19:32,Page318of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.42SSIB,HeadLossandChemicalBumpUp:Question 21aSTPResponse:(Item21a,Page74)AsstatedinSection5.6.2ofLAREnclosure4-3,SvvaluesforeachmaterialwerecalculatedbyCylindrically-shapeddebris:

S v=4/diamSpherically-shapeddebris:

S v=6/diamFlakes("at-plates):

S v=2/thickwherediamisthediameterofthe"berorsphericalparticleandthickisthethicknessofthe"ake/chip.Thegeometry,dimensions,andcalculatedSvvalues arepresentedinTables5.6.1and5.6.2ofLAREnclosure4-3.Thebasisofthese tablesisdescribedintheresponsetoSSIBRAI24.Notethat S vvaluesforchipdebriswerecalculatedinCASAGrandewiththesphericalformulausingsubstitutediametersthatproducevaluesequivalent tothe"akethicknessformula(mentionedinthefootnotesonPage179ofLAR Enclosure4-3).2.3.6.43SSIB,HeadLossandChemicalBumpUp:Question 21bSTPResponse:(Item21b,Page75)

The S vvaluesforindividualmaterialsweredeterminedusingcharacteristicdiametersinstandardgeometricformulasasshownintheresponsetoSSIBRAI 21a.ThebasisforthediametersusedisdisplayedintheresponsetoSSIBRAI 24.Basesformaterialdensities(microscopic)areprovidedinreferencestoLAR Enclosure4-3Table2.2.21.STPdoesnotagreethatphysicalmeasurementsofmaterialpropertiespre-cludeaccuratepredictionofheadloss.Ingeneral,independentmeasurements ofpropertiesandfreeparametersareessentialtovalidatethetheoreticalbasis ofanypredictivemodel.Thesupplementalreport(Enclosure1)illustrateshow measuredvaluescanbeusedtocalibrateanalternativehead-lossmodelthat reproducestialpressurehistorieswithgood"delity.2.3.6.44SSIB,HeadLossandChemicalBumpUp:Question 21cSTPResponse:(Item21c,Page75)UncertaintycausedbytherelationshipbetweenexperimentallydeducedSvandheadlossestimatesisdiscussedinLAREnclosure4-3asacautionarynote againstindiscriminantapplicationofdebrispropertiesmeasuredinthismanner.

Whenatheoreticalformulationisusedtoextractbedproperties,thespeci"c numericvaluesobtainedaretiedtotheaccuracyoftheformulaitself.Anin-herentpartofphysicsmodelsisthatanyinaccuraciesintheexplicitfactors(or form)ofamodelarerelegatedtothevaluesoffree(orunknown)parametersin themodel.Itisbettertodeterminematerialpropertiesandotherparameters independentlyifpossible.TheexampleexplainedinLAREnclosure3withrespecttoironoxideSvisagoodexampleofcon"rmationbycomparison.Surface-to-volumeratiowas usedlikeafreeparameterto"rstachievegoodagreementwiththepressuredrop measurements.ThecorrespondingsphericalparticlesizewasthencomparedtoTuesday1 stMarch,2016:19:32,Page319of393 DRAFTPART2.RAIRESPONSES(ROUND1)descriptionsofthebulkparticulatetocon"rmthatthenominalparticlesizewassimilar.AlldebrisSvusedintheLARarebasedongeometricapproximations ratherthanonexperimentallydeterminedvalues.Thus,thisformofpropagated uncertaintyisnotaconcernfortheanalysis.Inaccuracyinthegeometricap-proximationiscoveredbythefactorof5uncertaintyboundasdiscussedinthe responsetoSSIBRAI19.2.3.6.45SSIB,HeadLossandChemicalBumpUp:Question 21dSTPResponse:(Item21d,Page75)OneoftheencounteredinverticalheadlosstestingwithNEIprepared"berglassisachievingcomplete"ltrationofparticulatethatisintro-duced.Theratioofparticulateto"berresidentinthebedcalculation ofthecompositeporosity.Itisgenerallyconservativetoassumecomplete"l-trationsothatthein"uenceofdebrisonheadlossismaximized.Assumption ofcomplete"ltrationpartiallyexplainswhymeasuredheadlosseswereoveres-timatedbycalculation.AlthoughSTPdoesnothavethesurrogatematerials ofsiliconcarbideandtinpresentinthedebrisinventory,iftheywerepresent, useofthecorrelationinitspresentformwouldleadtoconservativeestimatesof headlossimpact.Similaroverestimationwouldbeobtainedforanyparticulates havingsimilarmaterialpropertiesandbeingresidentinsimilarquantities.In thissense,lackofpreciseagreementbetweentestandcalculationdoesnot theconclusionsoftheriskquanti"cation.ThesupplementarywhitepaperaccompanyingtheseRAIresponses(Enclo-sure1)providesvisualSEMcomparisonsofprototypicaldebristypesthatwere tested.Directmeasurementsofspeci"csurfaceareaforsiliconcarbide,acrylic coating,and"berglassareusedtodemonstrateagreementofanalternatehead-losscorrelationwithTests4and6thatweredescribedaschallenginginRefer-ence24ofLAREncl.4-3.Head-losspredictedbyconventionalimplementation of6224consistentlyoverestimatedvaluesmeasuredforTests1-4thatcontained low-density"berglassandsiliconcarbide.Goodpredictiveagreementwithtest datausinganindependentmodelprovidescon"dencethattheSTPLARappli-cationofNUREG/CR-6224(including5timesuncertaintyfactorandfullbed compression)doesnotunderpredict"owconditionsofinterest.2.3.6.46SSIB,HeadLossandChemicalBumpUp:Question 22STPResponse:(Item22,Page75)STPdoesnotagreethatobservationscitedinthisRAIaregenerallyappli-cabletoallcorrelationssimilartoNUREG/CR-6224.Independentcon"rmation ofthesurface-to-volumeratiofor"berglasssuggeststhatnocompensationis needed.Uncertaintiesinparticulatepropertiesthathavenotbeencon"rmedare addressedbythefactorof5uncertaintyboundappliedtoallpredictionsofthe model.Asexplainedinthewhitepaperaccompanyingthisresponse(Enclosure 1),thederivationoftheErgunequationandtheNUREG/CR-6224variantis basedonahydraulicscalingargumentthatdependsonthetotallocaldragarea andnotontheorientationofthedebriselements.Forexample,thecylindrical surface-to-volumeratioisapproximatedas S v=(h)/( 2 h/4)=4/d forTuesday1 stMarch,2016:19:32,Page320of393 DRAFTPART2.RAIRESPONSES(ROUND1)cylindricaldiameter dandlength h,wheretheverysmallfaceareaofthecylin-derendsisignored.Thepossibleinterpretationofcylindricalsurface-to-volume ratioasaratioofperpendicularperimetertoperpendicularareaisincomplete.Asamanufacturedproduct,"berglassdoeshavearelativelyuniformdi-ametercomparedtoirregularparticulatedistributions.Directmeasurementof speci"csurfaceareaforclean"berglassincombinationwithanassumedmate-rialdensityof2.8g/cm3(175lbm/ft3)givesasurface-to-volumeratioof594,282

m1,whichis4%higherthanthestandardassumptionof571,429m1obtainedbygeometricapproximationfora7

µmcylinder.TheslightlyhighermeasuredvaluecanbeattributedtothepresenceofbinderasnotedintheRAIstatement.

Independentcon"rmationofanimportantmaterialpropertyforoneofthedom-inantdebristypeslendscon"dencetouseofthegeometricapproximationfor "berglassinallapplicationsofNUREG/CR-6224foundintheLAR.AsdiscussedintheresponsetoSSIBRAI21c,adjustmentstofreeparame-tersbasedonagreementofamodelwithdatainherentlydependontheaccuracy andformofthemodelitself.Afterlonguse,certainconventionsbecomeembed-dedinthequanti"cationofimportantproperties;forexample,thefactorization of(1/2) 2inparticulatedragcots.However,itispreferabletohavein-dependentmeasurementsofkeyparametersthatdonotdependontheinherent accuracyofthetheoreticalmodel.Thewhitepapersupplementtothisresponse (Enclosure1)providesanexampleofmodelcalibrationusingindependently measuredmaterialproperties.2.3.6.47SSIB,HeadLossandChemicalBumpUp:Question 23STPResponse:(Item23,Page75)MaterialpropertiesofMicrothermwereprimarilytakenfromLAREnclosure4-3,Refeence[43,AttachmentE].ThereferencestatesthatMicrotherm"bers areglass"lamentsthatare6microns(6*10-6m)indiameterandhaveaspeci"c gravityof2.65.Usingtheaveragesurfacetovolumeratioequation(S v=4/diam),thesurface-to-volumeratiowascalculatedtobe666,667m 1.Usingthedensityofwateras62.43lb/ft3andtheequationSG microtherm

=Density microtherm

/Densitywater,themicroscopicdensityofMicrothermwascal-culatedtobe165lb/ft3.Microthermwassplitupintoitsconstituents("ber, SiO 2andTiO 2)tosimplifycharacterization.LAREnclosure4-3assumedthatMicrotherm"bersbulkdensityisthesameaslowdensity"berglass(LDFG) bulkdensity.2.4lb/ft3,thebulkdensityforLDFG,isareasonablevalueforthe bulkdensityofMicrotherm"berbecauseMicrotherm"berhasthesameshape andasimilarmicroscopicdensityand"berdiameterasLDFG.ResponsestoSSIBRAIs18band18cexplainmorecompletelytheuseofNukon"berbulkdensityforcalculatingthedebrisbedsurfacearea.Ingeneral, asludgecompactionlimitwasintendedforalldebrispackingdensitiessothat minimumthicknessisusedinthehead-losscalculations.2.3.6.48SSIB,HeadLossandChemicalBumpUp:Question 24STPResponse:(Item24,Page76)Tuesday1 stMarch,2016:19:32,Page321of393 DRAFTPART2.RAIRESPONSES(ROUND1)AsexplainedinresponsetoSSIBRAI21a,standardgeometricformulaswereusedtocalculatesurface-to-volumeratiosSvusingnominalrepresentativedebris sizes(radiiforcylindersandspheres,thicknessforchips).Characteristicvalues providedinSTPLAREnclosure4-3,Tables5.6.1and5.6.2arebasedlargelyon manufacturerandsupplierinformationdataaswellasondeterministicguidance referencedinexplanationofSTPLAREnclosure4-3,Table2.2.21.Thefollowing excerptcitesrelevantreferencesfromSTPLAREnclosure4-3:Table2.2.21providesthematerialproperties(sizeanddensity)forinsula-tion(43;46;45),quali"edcoatings(11;43),unquali"edcoatings(12),crud(13),

andlatentdebris(43)atSTP.Materialdensitiesbasedonmanufacturerspeci"cationsshouldbeaccuratetobetterthan

+/-10%.Cruddensitywasintentionallyselectedfromthelowerendofarange(350Ibm/ft3fromarangeof325to556lbm/ft3)leavinganasym-metricuncertaintybandof-1%to+60%.Lowermaterialdensityisconsidered conservativebecausetheparticulatetakesupmorespaceinsideofthedebris bedreducingporosityforagivencompactionratio.De"nitionofreasonableuncertaintybandsforconstituentsurface-to-volumeratioequatestode"ningreasonableuncertaintybandsonnominalsize.Ingen-eral,smallerparticlesizesleadtohigherheadlossandincreasedrisk,asdemon-stratedintheexamplebelow.Itshouldbenotedthat"berglass,beingamanu-facturedproductthatformsthedominantsubstrateforalldebrisbedsatSTP, hasaveryregulargeometryanddensity.Theassumed7-

µm"berdiameteriscon"rmedbySEMimagesandbydirectmeasurementof S v(Enclosure1),whichagreeswithin4%ofthegeometricapproximation.Uncertaintyrangesonthenominalsizeofotherconstituentsvary.Acruddiameterof15 mumwaschosenfromarangeof8to63 mum,leavinganasym-metricuncertaintyrangeof-47%and+320%.Failedunquali"edcoatingswere assignedasizeof10 mumfromarangeof4to20 mum,leavinganasymmetricuncertaintyrangeof-60%to+100%.Ofcourse,theremayberesidualuncer-taintiespresentinthede"nedrangesanduncertaintiesinthedistributionof particulatesacrossthestatedranges,conservatismwasintroducedbyselection ofsmallersizes(pointvaluesthatrepresentanentiredistribution)thanwould bepresentusingacompletewell-de"neddistributionofparticlesizesforeach constituent.Particlesize,andhence S v,wereintentionallynotselectedasran-domvariablesintheCASAGrandesamplematrixbecauseagreaterdegreeofconsensussupportstheadoptionofpointvaluesthanexistsforotherimportant parameters.Toinvestigatehowcompoundedinaccuraciesinassumedmaterialpropertiesmighthead-lossvaluespredictedbythecorrelation,aparameterstudywas performedwherealldebrisdiameterswerearti"ciallyincreasedby30%,causing a25%decreaseinAsimilarglobal30%decreaseindebrisdiameters causeda40%increaseinThe30%degreeofvariationinthiscasestudy representsasubstantialfractionofthereasonableuncertaintyrangesde"ned aboveforimportantparticulates,andimpactsoflessthan50%wereexperienced fromvariationsinsizecompoundedoveralldebristypes.Tuesday1 stMarch,2016:19:32,Page322of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.49SSIB,HeadLossandChemicalBumpUp:Question 27STPResponse:(Item27,Page77)Thecleanstrainerheadloss(CSHL)valueusedintheSTPCASAGrandeevaluationof0.220ftofH20wasreferencedfrom"SouthTexasProjectTest ReportforECCSStrainerPerformanceTesting"(LAREncl.4-3,Ref.53,Pg.39).

ThisCSHLvaluewasmeasureddirectlyfromthesingle-moduleheadlosstesting performedwithmaximum"owat116F,anddidnotincludethecalculatedeofincreasedheadlossesfortheentirestrainerassembly.TheCSHLvalueof1.952 ftofH20wascalculatedinPerformanceContracting,INCcalculationClean HeadLoss-SouthTexasProjectUnits1&2(Enclosure1)usingconservativeassumptions.TheCSHLvalueof1.952ftofH20giveninthecleanstrainerhead losscalculationwascalculatedunderthefollowingassumptions:

• Totallossescalculatedforthebounding6-moduleSTPstrainerassembly(allothershavefewermodules),*Nocredittakenforexpansionlosses(expansionfactor=1.0),*10%additionalheadlossaddedexpansionfactor,*6%conservatismaddedforcoretubelosses,*Valuecalculatedformaximum"owvelocityandmaximum(6)strainerstringatatemperatureof128F.Thetestedsingle-moduleCSHLvalue(LAREncl.4-3,Ref.53,Pg.39)of0.22ftofH20wasinadvertentlyusedastheCSHLvalueforthetotalassembly inSTPCASAGrandeevaluation.UsingthePCIcalculatedvalueof1.952ftof H20wouldincreasethetotalchangeincoredamagefrequency(value byapproximately18%fromthesubmittalcalculatedACDF.Thisinputerrorto theCASAGrandeevaluationisbeingtrackedundertheSTPcorrectiveaction programandtheAlioncorrectiveactionprogramtoassurethatamoreaccurate CSHLisincorporatedintheanalysisandprovidedinfuturesubmittals.

References 1.SouthTexasNuclearOperatingCompany,CleanHeadLoss-SouthTexasProjectUnits1&2(0415-0100055WN/0415-0200053WN),20062.3.6.50SSIB,HeadLossandChemicalBumpUp:Question 28STPResponse:(Item28,Page77)Useofahead-losscorrelationisessentialtotherisk-informedresolutionpro-cessbecauseitilluminatessubtleinteractionsbetweendebristypes,sourcetim-ing,operational"owrates,andtemperaturehistoriesthatwouldnototherwise beapparentusingengineeringjudgmentalone.Withoutaplausiblyrealisticcor-relation,itwouldbeimpossibletoask/answerquestionsabouttheimplications ofoverallparameterandmodelinguncertainty.Threekeyuncertaintiesresideintheapplicationofahead-lossmodel:(1)formofthemodelneededtocapturerelevantphysicsofhydraulicresistance,(2)Tuesday1 stMarch,2016:19:32,Page323of393 DRAFTPART2.RAIRESPONSES(ROUND1)materialpropertiesneededtodescribecontributionsofindividualdebriscon-stituents,and(3)bedcompression(eitheruniformornon-uniform)thatcontrols porosity.ResponsestootherRAIshaveaddressedeachtopicseparately,butthe aggregateapproachtouncertaintyinhead-losspredictionincludesthefollowing elements:(1)CompareperformanceofNUREG/CR-6224toanindependentlyderivedmodelandcomparebothtotestdatatodemonstrateconservativeperfor-manceofNUREG/CR-6224asappliedintheSTPLAR;(2)Interpretthefactorof5asanuncertaintyboundthatcoversinaccuraciesinindividualmaterialpropertiesandchemical(3)Applyasludgecompressionlimittoobviateconcernsaboutnon-uniformbedresponse.Whilethislimitmayultimatelyprovetobeoverlyrestrictive, itestablishesaboundonpossiblein"uencecausedbybedmechanics.OveralluncertaintieshavebeenaddressedintheSTPLARbysensitivitystudiesthatinterrogatethedegreeofin"uenceonintroducedbychanges inspeci"cparameters(Enclosure2).Theinteractionsofmaterialpropertiesare complexbecauseoftheircontributionstoweightedaveragebedpropertiesand canleadtonon-intuitiveresultsthatbothincreaseordecreaserisksomewhat.

ThesupplementalwhitepaperaccompanyingthisRAIresponse(Enclosure1) discussesonesuchparameterstudytheamountofepoxy"nematerial appearinginthepool.ThisperturbationdecreasedCDFbynomorethan10%.

Inoneparameterstudyperformedtosupportthisresponse,alldebrisdiameters werearti"ciallyincreasedby30%causinga25%decreaseinAsimilar global30%decreaseindebrisdiameterscauseda40%increaseinNote thatchangesindebrisdiametersimplydirectchangesintheassumedsurface-to-volumeratios S v.Parametervariationstudiesperformedthusfarlendcon"dencethatthefactorof5uncertaintyboundappliedtoallpressuredropcalculations istly,yetreasonably,conservative.Inthisapplication,thefactorof5is analogoustoasingle-sidedparametervariationthatcausesauniformshiftto higherheadloss.Becausethex5uncertaintyboundrepresentsanenvelopeofpotentialthatarenotfullyresolvedinthevalidationtests,asensitivitystudywasrunon thisfactorkeepingallotherinputsequaltothebaseline.Beingasimplemultiple onconventionalheadloss,changestothisparametercanbeviewedasshifting theentiredistributionofpredictedheadlossupordownrelativetothestrainer-relatedperformancecriteriaofNPSH,bucklinganddegasi"cation.The ofshiftingtheuncertaintyboundalongarangefrom1to7,whenappliedasa precisevaluewithnostandarddeviation,isillustratedinFig.A.Thein"uenceof thisparameteronCDFisnearlylinearintheregionabout5.0.Notethatthe baselinequanti"cationincludesastandarddeviationof1aboutameanfactor of5.Thisspreadallowsslightlymorecasestofailthanasharpvalueof5sothe ratioofriskatthisvalueislessthan1.0.2.3.6.51SSIB,NPSHandDegasi"cation:Question33 STPResponse:(Item33,Page78)Tuesday1 stMarch,2016:19:32,Page324of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:SensitivityofCDFtochangesinhead-lossuncertaintyboundpresentedasaratiotothebaselineThepoolwaterlevelwascalculatedusingEquation1ofLAREnclosure4-3,Rev.2inSection2.2.5usingthe"oorareaatthebottomofthepool.This standardpracticeofusingthe"oorareaatthebottomofthepooldoesnot accountforchangesinpoollevelwithelevationorchangesinobjectsthatmay displacewater.ACADcalculationwasperformedinsupportofthisresponsetocalculatepoollevelsasafunctionofwatervolumewithdisplacementfromequipment included.AcomparisonoftheCADandCASAGrandepoolelevationsare shownbelow.Aspoollevelsincrease,CASAGrandeoverestimates(ishigher than)thepoollevelwithrespecttotheCADdeterminedlevel.ThemaximumandaveragebetweenthehigherCASAGrandeelevationsandthelowerCADelevationsare7.0and5.1inches(10.6%and 9.8%)respectively.Theelevationswereevaluatedbetweentheminimumand maximumSTPpoolvolumes(LAREnclosure4-3,Pg.45).ThereisaninconsistencybetweenthelevelscalculatedusingthereferencedpoolareaandthecurrentlyQAapprovedCADmodelcalculatedlevels.This errorwillbetrackedintheSTPcorrectiveactionprogramandchangeswill bemadeinanyfuturesubmittalswhichwillincludeusingCADelevationsto determinepoollevels.2.3.6.52SSIB,NPSHandDegasi"cation:Question36 STPResponse:(Item36,Page78)ThebasisforthevaluesusedinLAREncl.4-3istheoperationandmain-tenancemanual(2and3)whichprovidetheNPSHrequiredatthepump"rst stageimpeller.Thiswasdeterminedbypumptestingandismetbythepump barreldesignwhichhasaheightof15ft.Table1displaystheNPSHrequiredatthepumpimpellerforeachpumpatthespeci"ed"owrate.However,verticalcentrifugalpumpshavetwoindependentNPSHrequiredTuesday1 stMarch,2016:19:32,Page325of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:ComparisonofCADandCASAGrandepoolelevationsversuswatervolumeTable1:NPSHRequiredatthePumpImpellerPumpFlowRate,gpmNPSHRequiredatthePumpImpeller,ftLHSI2,80013HHSI1,62011 CS2,70012values:1)atthe"rststageimpeller(describedabove)and2)atthepumpsuction nozzlelocatedatthetopofthepumpbarrel(1).WhiletheNPSHrequiredat thepumpimpellerisdeterminedbytesting,theNPSHrequiredatthepump suctionnozzleisequaltothevelocityheadatthetopofthesuctionnozzle(1) aspresentedbyEq1.NPSH R@suct=v 2 2 g+1 2 d(Eq1)Table2displaystheNPSHrequiredatthepumpsuctionnozzleforeachpumpatthespeci"ed"owrate.Table2:NPSHRequiredatthePumpSuctionNozzlePumpFlowRate,gpmNPSHRequiredatthePumpSuctionInlet,ftLHSI2,8001.5HHSI1,6201.1 CS2,7001.4LAREncl.4-3onlydeterminedtheNPSHmarginatthepumpimpeller.ACASAGrandeparameterstudywasconductedwheretheNPSHmarginwas calculatedatthepumpsuctionnozzle.Althoughthisinputcausedanetre-Tuesday1 stMarch,2016:19:32,Page326of393 DRAFTPART2.RAIRESPONSES(ROUND1)ductioninNPSHmargin,theACDFdidnotchangebecausestrainerbucklingisthelimitingfailurecriterion.Inotherwords,thenumberoffailuresdidnot changebecauseadditionalfailurescausedbytherevisedNPSHtreatmentwere alreadyfailingthestrainerbucklingcriterioninLAREncl.4-3.Theresponse toESGBRAI17intheSTPletterprovidedtotheNRCdatedJune25, 2014,NOC-AE-14003101,ML14178A481andML14178A485furthersupports thisobservationbystating:Achemicalhead-lossfactorof43wouldleadtobucklingfailureofthestrainerforallsimulatedbreaksinCase01,fulltrainoperation.

Achemicalhead-lossfactorof209wouldleadtotheviolationofthe NPSHmargincriterionandfailureforallsimulatedbreaksinCase 01,fulltrainoperation.EventhoughthecorrectionoftheNPSHevaluationwillhavenoontheconclusionsintheLAR,itisstillbeingtrackedintheAlioncorrectiveaction program.TheSTPUFSARalsorequiresclari"cationandtheconditionhasbeen loggedintotheSTPCorrectiveActionProgram.

References:

1.ST-WN-YB-1883.WestinghouseElectricCorporationLetter.8/29/1985.

2.VTD-P025-0001.LowHeadSafetyInjectionandContainmentSprayPumpsOperationandMaintenanceManual.Revision4.11/30/2004.3.VTD-P025-0004.HighHeadSafetyInjectionPumpOperationandMain-tenanceManual.Revision4.1/10/2007.2.3.6.53SSIB,NPSHandDegasi"cation:Question38 STPResponse:(Item38,Page79)No.Thefractionofdebristhatissheddableisnotdependentontheamountofdebrisonthebed.Thefractionofdebristhatissheddableisaconstantfor eachscenariothatissampledfromvariationsinobserveddata(LAREnclosure 4-3,Reference[28],Page.5).2.3.6.54SSIB,DefenseInDepthandMitigativeMeasures:Question 40STPResponse:(Item40,Page80)RegardingfailurethatmayoccurQuantitativeevaluationsofthedefenseindepthandsafetymarginasde-scribedintheLARshowthatpeakcladtemperatureremainsbelow800Fwith asinglefuelchannelunblockedorwith"owthroughthecorebypassthathas largeopeningsunlikelytoretaindebris.Thequantitativethresholdsofconcern usedforsuccesscriteria(forexample,7.5g/FAforcoreblockageorboricacid precipitationstrainerandnocreditforcontainmentoverpressure)supportasser-tionsmaderegardingtherequirementsinRG1.174.Althoughchemicalcorrosion areincludedaspartoftheengineeringsupportfortheriskanalysis,many experimentsperformedwithrealisticpost-LOCAexposuretopossibleprecipi-tateformationshowthatchemicalprecipitatesareunlikelytocausethehead lossesincludedintheLARsupportingengineeringanalyses(LAREnclosure4-3).TheRG1.174analysisdemonstratestheriskisverysmallandthereforetheTuesday1 stMarch,2016:19:32,Page327of393 DRAFTPART2.RAIRESPONSES(ROUND1)functionality,reliability,andavailabilityoftheECCSandCSSremainaccept-able.RegardingdefenseindepthDefenseindepthisprimarilyfocusedontheECCSfunctionsastheyrelatetocorecooling.TheconcernsrelatedtoGSI-191infactdonotbearoncontain-mentintegrityascontainmentcoolingisbythereactorcontainmentfancoolers, systemscompletelyindependentfromtheECCS.Infactthereisnoincreased likelihoodforcontainmentbreachfromtheconcernsrelatedtoGSI-191.This mayseemcounterintuitiveinlightofthe(verysmall)increaseinLERFfrom 8.6E-12/yrto1.40E-11/yrdocumentedintheLAR,page2of5.Thisincreaseis relatedtothefactthatthePRAanalyzescaseswhen,forexample,containment purgeisinprogressandcantbeisolatedwhenacoredamageeventoccurs.Since thereisaverysmallincreaseincoredamagefrequencyanalyzed,thisresultsin thesmallincreaseinLERF.TheLAREnclosure4-1,PartI,ProceduresandActivitiesintheLicensingBasis(startingonpage1)describesechangesinoperation,processes, procedures,anddesignthathavebeeneitherundertakenorstrengthened,or identi"edassupportingabalancedapproachtotheconcernsraisedinGSI-191.

Themostimportantamongthesewastheintroductionofstrainerscapableof withstandinglargedebrisloadsthatmayresultinthehypotheticalLOCAsce-nariosanalyzedinrelationtoGSI-191.Inaddition(describedaswellinPartI),

thedesignprocesshasbeenstrengthenedtopreventintroductionofpotentially harmfulproductsinthecontainmentbuilding,largetransitionweldssusceptible toPWSCCinareaswheremaximumtargetmaterialispresenthaveeitherbeen replacedormitigatedaccordingmodernindustrystandards.Thesteamgenera-tornozzleweldswerereplacedwithAlloy690whenthesteamgeneratorswere replaced,andthepressurizersafe-endweldshavebeenoverlaid.Thereactor vesselnozzlesarestillAlloy600,however,thereactorvesselusesstainlesssteel re"ectivemetalinsulationwhichisnotasumpdebrisconcern.TheregulatoryframeworkfortheSTPlicensingapplicationistoapplyarisk-informedanalysistodemonstratethattheeofdebrisonthesystemsthat supportthelong-termcoolingfunction(i.e.,ECCSandCSS)areacceptably smallandthosesystemsremainreliabletoperformtheirdesignfunction.EventhedeterministicapproachinvolvestheECCSdesignmeetingahighlevelofprobabilitythatECCSperformancecriteriawillnotbeexceeded.Forex-ample,95%probabilityinRegulatoryGuide1.157BestEstimateCalculationsofEmergencyCoreCoolingSystemPerformanceaddressesarelativelynarrow scopeofparametersthatcouldECCSperformance.Therisk-informedap-proachmakesnounconditionalassumptionsrelatedtosuccessandquanti"esa realisticcon"dencelevel.Therealisticriskforlossoflongtermcoolingiseval-uatedtobe"verysmall"intheexistingplantdesigninaccordancewiththe guidanceprovidedinRG1.174,whichcouldbeconsideredequivalenttoahigh levelofprobability.RegardingthehypotheticalcleanplantThehypotheticalcleanplantisdescribedinEnclosure1totheLARandisaplantthathasnosourcesofdebristhatwouldresultintheconcernsrelatedto GSI-191.Theas-built,as-operatedplanthas"brousinsulationthatisthesource oftheconcernsrelatedtoGSI-191.TherearematerialsincludedinthedesignTuesday1 stMarch,2016:19:32,Page328of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatmayinteractwith"brousdebris(includinglatentdebris)toadverselyheadlossand"owtothecore.RegardingequipmentchangesTherearenoproposedchangestohowanyequipmentisoperatedormain-tainedintheSTPapplication;consequently,nochangesareproposedintheLAR toequipmentavailability,functionality,orreliability.AsdescribedintheLAR, Enclosure2-1,Section1,STPNOCrequestsanexemptioninordertoenable theuseofarisk-informedmethodtodemonstrateacceptablesumpperformance andtovalidateassumptionsintheEmergencyCoreCoolingSystem(ECCS) evaluationmodel.2.3.6.55SSIB,DefenseInDepthandMitigativeMeasures:Question 42STPResponse:(Item42,Page81)TheeenessofmitigativemeasuresasdirectedbytheEOPsandSAMGsforinadequatereactorcore"owhasbeenevaluatedaspartofthedevelopment oftheproceduresandguidelines.NotallactionslistedinLAREnclosure4-1AppendixC,Section5.8requireuseofblocked"owpaths.Ifthecoreandcorebypassarebothblockedduring hypothesizedmediumorlargecoldlegbreakscenarios,transfertohotlegrecir-culationwouldbeeeincontinuingtocoolthecore.Forhypothesizedhot legbreakscenarios,orsmallcoldlegbreakscenarioswithcoreblockage,thecold leginjectionpathisallthatisrequiredasdescribedintheLAREnclosure4.3, Section5.10.2.Inadditiontotransfertohotlegrecirculationforthemedium andlargecoldlegbreakscenarioswithfullcoreandbypassblockage,theEOPs requirerunningreactorcoolantpumpsinresponsetoinadequatecorecooling.

Thereactorcoolantpumpdischargepressureofapproximately76psid(1)would beexpectedtocleardebrisorre-"oodthecore.Alternatively,iftheECCS"owpathisblocked,alternatesuccesspathsareprovidedindependentofcoreblockage.Chargingmayberestoredthrougheither thenormalcharging"owpath(viathevolumecontroltank)orthroughthe positivedisplacementpump.TheRWSTmaybeusedfollowingre"llabovethe EMPTYlevel.ThereisnoprocedureforbackwashingthestrainersatSTP.

Reference:

1.STPlettertoUSNRCdatedApril8,2014STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.July2013,ML14091A452Tuesday1 stMarch,2016:19:32,Page329of393 DRAFTPart3ResponsetoEPNBConsistencyofWeldFre-quencieswithRI-ISIProgram:RAI6Weinvestigatethediscrepancyinthefrequenciesofsmall,medium,andlargebreaksbetween:(i)NUREG-1829sTregoningetal.(2008) meanfrequencies,whichareusedinSTPssubmittal,and(ii)the pointestimatesderiveddirectlyfromRI-ISIvaluesFlemingetal.

(2011).Wefurtherdiscussthediscrepancyintheconditionalproba-bilitydistribution(giventhatabreakoccurred)governingbreaksize andweldcaseusing:(i)thesubmittalshybridapproach

?,which"tsJohnsondistributionstoNUREG-1829Tregoningetal.(2008) percentilesandusesRI-ISI,and(ii)onlytheRI-ISIpointestimates.(ENCLOSURE1)ResponsetoEPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6JeremyTejada,JohnHasenbein,andDavidMortonTheUniversityofTexasatAustin3.1EPNBConsistencyofWeldFrequencieswithRI-ISIPro-gram:RAI6ThestatementoftheEPNBConsistencyofWeldFrequencieswithRI-ISIPro-gram:RAI6isasfollows:ByletterdatedSeptember10,2012,theNRCapprovedtherisk-informedinserviceinspection(RI-ISI)programforthethird10-year inserviceinspectionintervalatSTP,Units1and2(ADAMSAcces-sionNo.ML12243A343).Pleasediscussthefollowing:A)PleasestateiftheLOCAfrequencyestimatesusedforweldsintheGSI-191submittalareconsistentwiththeLOCAfrequencyestimates usedintheRI-ISIprogram.Ifthecomparisonisappropriate,please providenumericalexamplesofthecomparison.Ifthecomparisonis notappropriate,pleaseprovideexplanation.B)IftheLOCAfrequenciesforweldsarenotconsistentbetweenthetwoanalyses,(1)pleaseidentifythedandexplainwhythere areand(2)pleasediscusswhytheLOCAfrequencies 330 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6proposedintheGSI-191submittalareacceptableiftheyarenotconsistentwiththatoftheRI-ISIprogram.3.2ConsistencyofLOCAFrequencyEstimates:GSI-191Sub-mittalandRI-ISITheLOCAfrequencyestimatesusedforweldsinSTPsGSI-191submittalarenotconsistentwiththeLOCAfrequencyestimatesusedintheRI-ISIanalysis.

STPsGSI-191submittalusesahybridapproachdetailedinPanetal.

?,whichcombinesinformationfromtheRI-ISIanalysisFlemingetal.(2011)(plant-speci"cinformation)withtheLOCAfrequenciesinNUREG-1829Tregoning etal.(2008)("eet-wideinformation).Thislackofconsistencyinouranalysisisbydesign.Speci"cally,wemaintainconsistencywithNUREG-1829frequenciesforpiperupturesatvariousbreak sizes,andatthesametime,weuseplant-speci"cinformationFlemingetal.

(2011)todistributethesefrequenciesacrossweldcaseswithinabreaksize.We seeourapproachasconsistentwiththeNRCscommentsUhle(2005)onthe analysisofHochreiter(2005).TheanalysesofFlemingetal.(2011)andHochre-iter(2005)aresimilarinthattheyemployinformationregardingafrequencyof degradationratherthanafrequencyofpiperupture.WeseetheRI-ISIanaly-sisFlemingetal.(2011)ashavingvalueininformingtheconditionalprobability ofpiperupturewithinabreaksize,butweusetheexpertelicitationTregoning etal.(2008),whichfocusedonpiperuptures,toinformfrequenciesofbreaks acrossbreaksizes.Forthereasonsjustdiscussed,wedonotseeanumericalcomparisonasnecessarilyappropriate.Thatsaid,inrespondingtoB)wedoprovideanumerical comparisonofthetwoapproachesvia:(i)themeanfrequenciesofsmall(0.5-inch to2-inch),medium(2-inchto6-inch),andlarge(6-inchandgreater)breaksused inSTPsPRA,and(ii)thejointprobabilityofbreaksizeandweldcase,given thatthereisabreak.3.3EstimateofCDFOurpointestimateofCDFinformsatwo-partanalysisinthisdocument.WeestimateCDFasfollows:CDF=f SL*P (FailurelSL)+f ML*P (FailurelML)+f LL*P (FailurelLL).(Eq1)Here, SL , ML,and LLdenotetheeventsofasmall,medium,orlargebreak,and f SL , f ML,and f LLdenotecorrespondingmeanfrequenciesineventsperyear.AGSI-191failureevent,whetherinthesumporvessel,isdenotedFailure ,andthecorresponding PtermsareconditionalprobabilitiesestimatedusingtheCASAGrandesimulationmodel.Therespectivefrequenciesofasmall,medium,andlargebreak(f SL , f ML , and f LL)usedinSTPssubmittalarereportedinVolume2sTable4-1Wake"eldandJohnson(2013),andmatchlinearlyinterpolatedmeanfrequenciesfrom Table7.19(current-dayvalues)ofNUREG-1829Tregoningetal.(2008),atleast whenweformtocomputewithin-binfrequencies.InSection3.4,weTuesday1 stMarch,2016:19:32,Page331of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6comparethefrequencies, f SL , f ML,and f LL,basedonNUREG-1829meansandbasedonpointestimatesfromtheRI-ISIanalysisFlemingetal.(2011).STPssubmittalfurtherusesahybridapproach

?,which"tsJohnsondistri-butionsto NUREG-1829Tregoningetal.(2008)percentilesandthenusespointestimates fromtheRI-ISIanalysisFlemingetal.(2011)toconstructajointprobability distributiongoverningbreaksizeandweldcase.GiventhatwehaveaLOCA event,thisjointdistributionisusedintheCASAGrandesimulationmodelto formthethreeestimatesoftheconditionalfailureprobabilities,P (FailurelSL),P (FailurelML),andP (FailurelLL),usedinequation(Eq1).InSection3.5,wecomparethejointdistributionsobtainedusingthehybridapproach

?andthosederivedfromtheRI-ISIanalysisFlemingetal.(2011).3.4FrequenciesofSmall,Medium,andLargeBreaksInTable1wepresentthefrequenciesusedinequation(Eq1)basedonNUREG-1829andRI-ISI.ThetablesNUREG-1829Meanrowreportscurrent-dayval-uesfromTable7.19ofTregoningetal.(2008),usinglinearinterpolationtoobtain exceedancefrequenciesfor2-inchand6-inchbreaks,andformingdto "ndwithin-categoryfrequenciesfor0.5-2.0-inchbreaks(Small)and2.0-6.0-inch breaks(Medium).TheLargevalueisbasedonthe6.0-inchexceedancefre-quency.RowRI-ISIPointEstimatecontainsanalogousvaluesbasedonthe pointestimatesreportedinFlemingetal.(2011)sTables5.1-5.4.The"nalrow ofthetableshowstheratiosofthesefrequenciesusingRI-ISIasthedenomina-tor.ThisrowindicatesthattheNUREG-1829meanfrequenciesusedinSTPs submittalarelargerthanthoseofRI-ISIbyfactorsof4.43,15.18,and2.27for small,medium,andlargebreaks.Table1:Frequencies(eventsperyear)forsmall,medium,andlargebreaksforNUREG-1829andRI-ISI.Here,Small,Medium,andLargecorrespondtobreaksinthe 0.5-2.0-inchcategory,2.0-6.0-inchcategoryand6.0-inch-or-greatercategory.Method/BreakSizeSmallMediumLargeNUREG-1829Mean1.59E-033.05E-045.20E-06RI-ISIPointEstimate3.59E-042.01E-052.29E-06Ratio(NUREG/RI-ISI)4.4315.182.273.5ProbabilityDistributionsGoverningBreakSizeandWeld CaseInTables2,3,and4weshowtheprobabilitydistributionsgoverningbreaksizeandweldcaseobtainedusingthehybridapproachforSTPssubmittaland theRI-ISIanalysis.Thetablesreportprobabilitydistributionsgoverningbreak sizeandweldcase,conditionalontheoccurrenceofaLOCA.Table2shows theprobabilityofabreakfallingintheNUREG-1829categories1-6forboth methods.Here,theHybrid-JohnsonMeansrowisbasedonthemeansofthe Johnsondistributions"ttothepercentileselicitedinNUREG-1829TregoningTuesday1 stMarch,2016:19:32,Page332of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6etal.(2008).TheRI-ISI-PointEstimaterowisbasedonthepointestimatesreportedintheRI-ISIanalysisFlemingetal.(2011).Thetables"nalrowshows theratiooftheprobabilitiesforeachofthesixcategories,usingthehybrid methodasthedenominator.ThetableshowsthattheRI-ISIanalysishassimilar probabilitymassasNUREG-1829incategory1andasmallerprobabilitymassin category2.Thisdecreaseincategory2,coupledwiththesmallerfrequencyata 0.5-inchbreak(normalizationbythisfrequencyyieldsexceedanceprobabilities) leadstoincreasedprobabilitymass,underRI-ISI,beingdistributedtocategories 3-6byfactorsof2.70,5.03,20.38,and15.68.Table2:ConditionalLOCAprobabilitiesbycategoryusingboththehybridmethodwiththeJohnsonmeansandRI-ISIpointestimates.Theratiosoftheprobabilities (latterdividedbyformer)forthetwomethodsareshowninthebottomrow.Method/CategoryCat1Cat2Cat3Cat4Cat5Cat6Hybrid-JohnsonMeans8.02E-011.91E-016.85E-036.82E-045.12E-057.72E-06RI-ISI-PointEstimate9.08E-016.84E-021.85E-023.43E-031.04E-031.21E-04Ratio(RI-ISI/Hybrid)1.130.362.705.0320.3815.68Table3showsthejointprobabilitydistributionacross45weldcases,basedoncurrent-dayestimatesforthehybridapproachusingthemeansofthe"tted Johnsondistributions.ThebottomrowofTable3correspondstothetoprowof Table2.Theright-mostcolumnofTable3showstheconditionalprobabilityofa breakoccurringineachweldcase,giventhatabreakoccurred.Table4presents thesameinformationwhenusingtheRI-ISILOCAfrequencypointestimates.Tuesday1 stMarch,2016:19:32,Page333of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6Table3:JointLOCAprobabilitiesforbreaksizeandweldcaseusingthemeansofthe"ttedJohnsondistributionsforcurrent-dayestimates.WeldCaseCat1Cat2Cat3Cat4Cat5Cat6 P(Break)Weld1-1A2.92E-031.18E-031.18E-041.83E-052.73E-061.13E-06 4.24E-03Weld2-1B3.90E-051.58E-051.57E-062.45E-073.65E-081.51E-08 5.66E-05Weld3-1C2.27E-059.20E-069.15E-071.42E-072.12E-088.81E-09 3.30E-05Weld4-21.43E-025.84E-035.87E-049.60E-051.28E-055.72E-06 2.09E-02Weld5-3A1.11E-035.10E-043.79E-055.07E-067.34E-073.87E-07 1.66E-03Weld6-3B1.11E-035.10E-043.79E-055.07E-067.34E-073.87E-07 1.66E-03Weld7-3C6.12E-052.82E-052.10E-062.81E-074.06E-082.14E-08 9.19E-05Weld8-3D1.22E-045.65E-054.20E-065.62E-078.13E-084.29E-08 1.84E-04Weld9-4A1.54E-021.10E-021.09E-031.76E-041.52E-05X 2.77E-02Weld10-4B8.24E-045.86E-045.83E-059.37E-068.13E-07X 1.48E-03Weld11-4C3.84E-042.73E-042.72E-054.37E-063.79E-07X 6.89E-04Weld12-4D7.06E-045.02E-047.03E-05XXX 1.28E-03Weld13-5A2.34E-031.74E-036.65E-055.95E-06XX 4.15E-03Weld14-5B1.13E-038.39E-043.75E-05XXX 2.01E-03Weld15-5C1.60E-031.19E-035.31E-05XXX 2.84E-03Weld16-5D1.21E-048.97E-054.01E-06XXX 2.15E-04Weld17-5E8.77E-046.50E-042.49E-052.23E-06XX 1.55E-03Weld18-5F0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld19-5G1.23E-049.09E-053.48E-063.11E-07XX 2.17E-04Weld20-5H6.05E-054.48E-052.00E-06XXX 1.07E-04Weld21-5I1.62E-041.60E-04XXXX 3.22E-04Weld22-5J0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld23-6A3.52E-023.20E-02XXXX 6.72E-02Weld24-6B5.47E-01XXXXX 5.47E-01Weld25-7A1.03E-017.76E-022.68E-031.91E-041.64E-05X 1.83E-01Weld26-7B4.40E-023.33E-021.15E-031.10E-04XX 7.85E-02Weld27-7C1.64E-021.24E-024.27E-044.10E-05XX 2.92E-02Weld28-7D1.87E-031.41E-034.88E-053.48E-063.00E-07X 3.34E-03Weld29-7E1.15E-038.65E-042.99E-052.13E-061.83E-07X 2.04E-03Weld30-7F6.03E-044.55E-041.57E-051.12E-069.65E-08X 1.08E-03Weld31-7G8.44E-046.38E-042.20E-052.11E-06XX 1.51E-03Weld32-7H4.62E-043.49E-041.21E-051.16E-06XX 8.24E-04Weld33-7I1.00E-047.59E-053.09E-06XXX 1.79E-04Weld34-7J1.81E-041.37E-045.56E-06XXX 3.23E-04Weld35-7K2.01E-041.98E-04XXXX 3.99E-04Weld36-7L0.00E+000.00E+00XXXX 0.00E+00Weld37-7M0.00E+000.00E+000.00E+000.00E+000.00E+00X 0.00E+00Weld38-7N3.20E-032.41E-038.37E-055.98E-065.15E-07X 5.70E-03Weld39-7O1.65E-041.25E-044.33E-063.10E-072.66E-08X 2.95E-04Weld40-8A7.55E-045.65E-042.35E-05XXX 1.34E-03Weld41-8B1.44E-031.07E-034.46E-05XXX 2.55E-03Weld42-8C1.55E-031.16E-034.83E-05XXX 2.76E-03Weld43-8D1.98E-041.48E-046.17E-06XXX 3.53E-04Weld44-8E5.63E-044.21E-041.75E-05XXX 1.00E-03Weld45-8F3.30E-052.47E-051.03E-06XXX 5.88E-05 P(Break)8.02E-011.91E-016.85E-036.82E-045.12E-057.72E-06 1.00E+00EstimatesofpiperupturefrequenciesinformtwokeyaspectsoftheanalysisinSTPsGSI-191submittal.Thesetwoaspectsareapparentinequation(Eq1),

whichinvolvesmeanfrequenciesofsmall,medium,andlargebreaksandcon-Tuesday1 stMarch,2016:19:32,Page334of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6Table4:JointLOCAprobabilitiesforbreaksizeandweldcaseusingpointestimatesfromRI-ISIFlemingetal.(2011).WeldCaseCat1Cat2Cat3Cat4Cat5Cat6 P(Break)Weld1-1A3.31E-034.25E-043.18E-049.23E-055.57E-051.78E-05 4.22E-03Weld2-1B4.42E-055.67E-064.24E-061.23E-067.44E-072.37E-07 5.63E-05Weld3-1C2.57E-053.30E-062.47E-067.17E-074.33E-071.38E-07 3.28E-05Weld4-21.62E-022.10E-031.58E-034.83E-042.61E-048.97E-05 2.07E-02Weld5-3A1.25E-031.83E-041.02E-042.55E-051.50E-056.07E-06 1.58E-03Weld6-3B1.25E-031.83E-041.02E-042.55E-051.50E-056.07E-06 1.58E-03Weld7-3C6.94E-051.01E-055.66E-061.41E-068.28E-073.36E-07 8.77E-05Weld8-3D1.39E-042.03E-051.13E-052.83E-061.66E-066.73E-07 1.75E-04Weld9-4A1.75E-023.94E-032.95E-038.84E-043.10E-04X 2.56E-02Weld10-4B9.34E-042.10E-041.57E-044.72E-051.66E-05X 1.37E-03Weld11-4C4.35E-049.81E-057.33E-052.20E-057.72E-06X 6.36E-04Weld12-4D8.00E-041.80E-041.89E-04XXX 1.17E-03Weld13-5A2.65E-036.24E-041.79E-043.00E-05XX 3.49E-03Weld14-5B1.28E-033.01E-041.01E-04XXX 1.68E-03Weld15-5C1.82E-034.27E-041.43E-04XXX 2.39E-03Weld16-5D1.37E-043.22E-051.08E-05XXX 1.80E-04Weld17-5E9.94E-042.33E-046.71E-051.12E-05XX 1.31E-03Weld18-5F0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld19-5G1.39E-043.26E-059.38E-061.57E-06XX 1.82E-04Weld20-5H6.85E-051.61E-055.40E-06XXX 9.00E-05Weld21-5I1.83E-045.75E-05XXXX 2.41E-04Weld22-5J0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld23-6A3.99E-021.15E-02XXXX 5.14E-02Weld24-6B6.20E-01XXXXX 6.20E-01Weld25-7A1.16E-012.79E-027.23E-039.60E-043.35E-04X 1.53E-01Weld26-7B4.99E-021.19E-023.10E-035.55E-04XX 6.55E-02Weld27-7C1.85E-024.44E-031.15E-032.07E-04XX 2.43E-02Weld28-7D2.12E-035.08E-041.32E-041.75E-056.11E-06X 2.78E-03Weld29-7E1.30E-033.11E-048.06E-051.07E-053.74E-06X 1.70E-03Weld30-7F6.83E-041.64E-044.24E-055.64E-061.97E-06X 8.96E-04Weld31-7G9.56E-042.29E-045.94E-051.06E-05XX 1.26E-03Weld32-7H5.24E-041.25E-043.25E-055.83E-06XX 6.87E-04Weld33-7I1.14E-042.73E-058.34E-06XXX 1.49E-04Weld34-7J2.05E-044.91E-051.50E-05XXX 2.69E-04Weld35-7K2.28E-047.12E-05XXXX 2.99E-04Weld36-7L0.00E+000.00E+00XXXX 0.00E+00Weld37-7M0.00E+000.00E+000.00E+000.00E+000.00E+00X 0.00E+00Weld38-7N3.62E-038.66E-042.26E-043.01E-051.05E-05X 4.75E-03Weld39-7O1.87E-044.48E-051.17E-051.56E-065.43E-07X 2.46E-04Weld40-8A8.56E-042.03E-046.34E-05XXX 1.12E-03Weld41-8B1.63E-033.85E-041.20E-04XXX 2.13E-03Weld42-8C1.76E-034.17E-041.30E-04XXX 2.31E-03Weld43-8D2.25E-045.32E-051.66E-05XXX 2.94E-04Weld44-8E6.38E-041.51E-044.72E-05XXX 8.37E-04Weld45-8F3.74E-058.87E-062.77E-06XXX 4.91E-05 P(Break)9.08E-016.84E-021.85E-023.43E-031.04E-031.21E-04 1.00E+00ditionalfailureprobabilities.TheformerarepreciselythefrequenciesthatwediscussinSection3.4,andestimatesofthelatterprobabilitiesareformedus-Tuesday1 stMarch,2016:19:32,Page335of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6ingCASAGrande,basedonthejointprobabilitydistributionsthatwediscussinSection3.5.Inbothcases,wepreservecharacteristicsofNUREG-1829,an expertelicitationconcerningpiperupturefrequencies.ThemeanfrequenciesreportedinNUREG-1829Tregoningetal.(2008)arepreservedinthemeanfrequenciesdenoted f SL , f ML,and f LLinequation(Eq1).InSection3.4,weindicatethatifweretoinsteaduseRI-ISI,thesethreefre-quencieswoulddecreasebyfactorsof4.43,15.18,and2.27forsmall,medium, andlargebreaks.The5th,50th,and95thpercentilesofNUREG-1829frequenciesarepre-servedintheJohnsondistributionsusedinourhybridapproach

?,andwefurtherusetherelativefrequenciesinRI-ISIFlemingetal.(2011)toallocate failureswithinabreak-sizecategoryacrossweldcases.Ifweinsteaduseonly RI-ISIfrequenciestoconstructthedistributionoverbreaksizeandweldcase, theprobabilitymassincreasesbyfactorsof5.03,20.38,and15.68inthere-spectivecategories4,5,and6.Thisresultoccursforthreeprimaryreasons:

(i)theexceedancefrequencyatthesmallestbreaksize(0.5inch)issmallerin RI-ISIFlemingetal.(2011)thanNUREG-1829byafactorofnearly"ve(com-pare0.5-inchexceedancefrequenciesinTable5-6inFlemingetal.(2011)and Table7.19inTregoningetal.(2008));(ii)category2inRI-ISIhasasmaller probabilitymassthanthatfromNUREG-1829byafactorof0.36(seeTable2in Section3.5);and,(iii)thedegradation-basedfrequenciesinRI-ISIFlemingetal.

(2011)dropmoreslowlythanthepipe-rupturefrequenciesinNUREG-1829, particularlyincategories4-6.Wenotethatobservation(iii)isconsistentwiththe"attertrendsatlargerpipesizesreportedinthedegradationfrequency"analysisofHochreiter(2005).

Thatsaid,theapproachinSTPssubmittalinsteadmatchesthetrendsin NUREG-1829atlargerpipesizes,consistentwithcommentsinUhle(2005).Tuesday1 stMarch,2016:19:32,Page336of393 DRAFTPart4RAIResponses(Round2)4.1ML15091A440,APLABResponses4.1.1Question1:ProjectQualityAssuranceSTPResponse:(Item1,Page83)TheLARriskassessmentisbasedontheSTPNOCprocedureOPGP05-ZE-0001PRAAnalyses/AssessmentsundertheSTPOperationsQualityAssur-anceProgram(OQAP).TheprocedurestepswerecompletedbyABSConsulting personnelandSTPNOCPRAQuali"edAnalysts.ABSConsultingpersonnelare quali"edtotheSTPNOCprocedure.Allsupportinganalysesandcalculations wereperformedwithintheGSI-191QAprocessassummarizedintheLAREn-closure4-1,pagexx,Figure4,IllustrationofthemajorelementsoftheSTP qualityassuranceplanforrisk-informedclosureofGSI-191.Inaddition,theanalyses,calculation,andmethodologiesusedwerereviewedbyanindependentoversightgroup,UniversityofIllinoisatUrbana-Champaign.STPsstationcorrectiveactionprogramensuresthatappropriateattentionandcorrectiveactionsaretakenifassumptions,analyses,orinformationusedin previousdecisionmakingarechanged(e.g.,licenseevoluntaryaction)ordeter-minedtobeinerror.4.1.2Question2:ProjectQualityAssuranceSTPResponse:(Item2,Page83)AlionScienceandTechnology(Alion)isperformingtheSoftwareValidationandVeri"cationundertheauspicesofAlionsQualityAssuranceManualand QualityAssuranceProceduresreferredtoasAlionsQAProgram.TheQAPro-gramcomplieswith10CFR50AppendixBandNQA-1requirementsandhas beenauditedandapprovedbynumerousutilities,NUPICandNIAC.STPNOChasprovidedAlionwithOPGP07-ZA-0014,Revision9,SoftwareQualityAssuranceProgram.TherequirementsofOPGP07-ZA-0014andAlions complianceareprovidedinTable1.PerOPGP07-ZA-0014,CASAGrandeis classi"edasLevel3Software.TherequirementsforLevel3areprovidedbelow inTable10.1,excerptfromOPGP07-ZA-0014,Revision9.AtpresenttimeAlionhasmodi"edCASAGrandeandVersion1.7willbetheVeri"edandValidatedversionAlionwillissuetoSTPinadditiontothe aforementionedrequireddocuments.TheanticipateddateofissueisApril2, 2015.337 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:0PGP07-ZA-0014requirement,AlionscomplianceSTPALIONRequirementsSoftwareRequirementsSpeci"cationDesignSoftwareDesignSpeci"cation/TheoryManual UsersManualUsersManual TestProtocolSoftwareAdequacy/ValidationPlan TestPlanValidationPlan InstallationInstructions(UM)InstallationInstructions/UsersManualTable2:Table10.1excerptfrom0PGP07-ZA-0014,Revision9)Level1Level2Level3Level4Level5RequirementDocumentXXXXDesignDocumentXXX TestPlanDocumentXXX TestCaseDocument XXXXTestReportNote 1 Note 1 Note 1 Note 1UserInstruction/ManualNote 2 Note 2 Note 2 Note 2RetirementPlanDocumentNote 3 Note 3 Note 3 Note 3 1Requiredifthereare5ormoreTestCases 2SponsordeterminestheneedforaUserInstruction/Manual 3Requiredonlywhenthesoftwareordataisremovedfromaccessbyusers4.1.3Question3:ProjectQualityAssuranceSTPResponse:(Item3,Page84)ThePRAanalysisisnotrequiredtomeetAppendixBrequirements.ThePRAanalysisisundertheSTPOQAP.Vendorswerecontractedtoworkto acommonengineeringstandardthatrequiredapreparer,reviewer,andap-proval.Independentoversightwasalsopartoftheprocess.Asshowninthe"ow chartinEnclosure4-1,pagexx,vendor-supplieddocumentsandcalculationsare processedthroughSTPNOCEngineeringProcedure0PGP04-ZA-0328.RoverD utilizesdeterministicanalysespreviouslyperformedinsupportoftheDecember 2008submittalinresponsetoGL2004-02.Thesewereperformedinaccordance withAppendixBrequirements.Theserequirementswereinvokedbythecon-tractsSTPNOChadwithWestinghouseandwithPerformanceContractingInc.

(PCI).Thesub-contractorsincludedAlion;Enercon;Areva;andAutomated Engineeringservices(AES).Workbythesesub-contractorswasalsotoApp.B requirements.Inaddition,thesumpdesignandconstructionwasperformedinaccordancewithApp.Brequirements.4.1.4Question4:ProjectQualityAssuranceSTPResponse:(Item4,Page84)Asshowninthe"owchartinEnclosure4-1,pagexx,vendordocumentsareTuesday1 stMarch,2016:19:32,Page338of393 DRAFTPART4.RAIRESPONSES(ROUND2)processedthroughSTPNOCEngineeringProcedure0PGP04-ZA-0328.Introduction TheSTPrisk-informedGSI-191pilotprojectqualityassuranceprocessisillustratedinFigure1below.Asshowninthe"gure,projectcontractorsdevel-opinginputstothePRAarerequiredtohavealocalqualityassuranceprogram.

Ingeneral,thequalityassuranceprocessesthevendorsadoptedareuniqueto theprojectbutneverthelessincorporatestandardandgenerallyacceptedqual-ityassurancepractices.Eachvendorsprogramisdescribedinmoredetailin followingsections.Thevendorpersonnelassignedtotheprojectandresponsibleforproductqualityatthevendorlocationarequali"edtodoworkonthespeci"c(risk-informedpilot)projectpertheSTPNOCplantprocedure0PGP03-ZT-0138.In addition,theprojectusesindependenttechnicaloversightreviewforcriticalpeer reviewontheworkperformed.Aquali"edSTPNOCPRAanalystisultimatelyresponsibleforensuringthePRAinputsarereasonableforuseinthePRA.Personnelquali"edtothe STPanalysis/assessmentproceduretoperformPRAcalculationspertheSTP engineeringquali"cationprogramusethePRAinputs.Theoverallprogrammatic requirementsforPRAprojectsarecapturedin0PGP04-ZA-0604,Probabilistic RiskAssessmentProgram.Tuesday1 stMarch,2016:19:32,Page339of393 DRAFTPART4.RAIRESPONSES(ROUND2)FIGURE1Tuesday1 stMarch,2016:19:32,Page340of393 DRAFTPART4.RAIRESPONSES(ROUND2)ABSConsulting[ProbabilisticRiskAssessment]QualityProgramAspects:ABSconsultingpersonnelworkingontheprojectarequali"edtoperformtheSTPNOCplantprocedure0PGP05-ZE-0001,PRAAnalyses/Assessments.

0PGP05-ZE-0001isusedforallSTPPRAassessments,calculations,andappli-cationswhendataarebeingdevelopedoranalysesarerequired.Eachanalysisperformedin0PGP05-ZE-0001isassignedauniqueIDandrevisionnumber.TheIDfortherisk-informedGSI-191pilotlicensesubmittalis PRA-13-001,Revision0.Analysesandassessmentsmayberevisedasnecessary tore"ectnewinformationorchangedrequirements.TexasA&M[Thermal-Hydraulics]

QualityProgramAspects:Thethermal-hydraulicsmodelsarenewworkforSTP.Thatis,therisk-informedpilotprojectdidnotadoptexistingmodelsofcontainment,RCS,and ECCSduetolimitationsinthemodelingsoftware,nodalization,andapplication modellimitations.TheTAMUqualityplanfollowsstandardengineeringpracticerequiringonequali"edindividualtodevelopananalysisandasecond,independentreviewerto validatethework.Inaddition,thermal-hydraulicspracticeincludesveri"cation oftheinputsforthesimulationbycomparisonagainst(expected)steady-state (time-invariantboundaryconditions)andtransients.Becausethesimulationis foranoperatingplant,thesteady-stateoperatingpointisobtainedfromplant measurements.Inaddition,unmeasuredstatepointsarecon"rmedagainstother engineeringanalysesanddesignvalues.Existingsimulations(MAAP,RETRAN, licensingapplications)areusedforfurthersupport.Thetransientveri"cationfollowssteady-stateveri"cationandsince,ingen-eral,nodataexistformanyofthetransientssimulated,thesimulationisveri"ed againstotheracceptedtransientanalysessuchastheplantsimulator,UFSAR Chapter15analyses,andgenericanalysesintheopenliterature.Theresults ofthethermal-hydraulicmodelveri"cationsarecapturedindocumentsspeci"c totheveri"cation.Foreachspeci"ctransientcasecalculatedforuseintheengineeringanal-yses,thegenerallyacceptedengineeringpracticeofpreparerandreviewerwas followed.Eachindividualtransientanalysisisdocumentedinareportthatis identi"edwiththepreparerandreviewer.Thescopeofreviewincludesnotonly appropriateinputdatabutreasonablenessoftheresultsaswell.Anyresults thatappearedinconsistentwithintuitionwerestudiedandexplained.AlionScienceandTechnology[EngineeringAnalysis&Quanti"cation(CASA Grande)]QualityProgramAspects:AtthetimeFigure1wasdevelopedresponsibilityforengineeringanalysisandquanti"cationwaswithLANL.Subsequently,theseresponsibilitieswere transferredtoAlionScience.Therisk-informedpilotprojectscopeofworkwas deemednon-safetyandthereforenotperformedunderAlions10CFR50Ap-pendixB,10CFRPart21andASMENQA-1-1994QualityAssuranceProgram;Tuesday1 stMarch,2016:19:32,Page341of393 DRAFTPART4.RAIRESPONSES(ROUND2)however,forAlionsdevelopmentandreviewofcalculationsforthenon-safetyproject,bestengineeringpracticeswerefollowed.Theinitialstageofthenon-safetyprojectregardingCASAGrandewastodevelopthecalculationaltool, verifytheaccuracyofthetool,beginsoftwaredevelopmenttodevelopthecode, runatestcaseandperformacomparison.Testcaseswithcon"rmationusing handcalculationswereusedtoverifythattheCASAGrandecalculationalmeth-odswereaccurateandproper.ThecurrentSQAisdescribedintheresponseto RAI2above.UTAustin[UncertaintyQuanti"cation]

QualityProgramAspects:UTusesstandardqualitycontrolaspectsforanalyses,documents,andtech-nicalreports.Thisconsistsprimarilyofapreparer,areviewer,andanapprover (eitherinternaltoUTorexternal).UniversityofNewMexico[Chemical QualityProgramAspects:AllchemicalexperimentsworkisperformedusingtheUNMqualityassuranceprogrammanual,"Corrosion/HeadLossExperiments(CHLE)Project QualityAssuranceProgramManualRevision2",June18,2012.Standardlabo-ratorypracticewasfollowedforkeepinglaboratorynotesandobservations.UNMhasbeenperformingtheCorrosionHeadLossExperimental(CHLE)Programunderthequalityassuranceprogramthatwasdevelopedforthisproject.

Aspartofthisprogram,allcalculationsforconductingatestareperformedby onepersonandcheckedbyadtindividual.Metalionconcentrationshave beenanalyzedbyacommerciallabandinstrumentssuchaspHmetersandbal-anceshavebeencalibratedwithappropriatestandards.Writtenprocedureswere preparedandfollowedforeachtanktest.Aftereachexperimentwasconducted, areportwaswritten.ThatreportwascheckedbyaseparateindividualatUNM andwasthencheckedbyanindividualatSTPandanotherindividualatSo-teria/UIUCConsultants.Basedontheprocedurewehavefollowedforreport writingandchecking,wearenotawareofanyinaccuraciesbetweenthetests thatwereactuallydoneandtheresultsthatarereportedinthecorresponding reports.UniversityofIllinoisatUrbana-Champaign[TechnicalOversight]

AteamfromtheUniversityofIllinoisatUrbana-Champaign(UIUC)hasbeenprovidingIndependentTechnicalOversightoftheSTPNOCRisk-Informed GSI-191project.TwokeymembersofthisteamwerewithSoteriaCon-sultants(Soteria)in2012;therefore,theOversightfunctionwascarriedoutun-derSoteriathatyear.InJanuary2013,thetwokeymembersjoinedthefaculty oftheNuclearEngineeringDepartmentatUIUCand,fromthattime,theInde-pendentOversightoftheSTPprojectwasperformedunderacontractbetween STPNOCandUIUC.STPNOCcommissionedtheIndependentOversightteamtohelpensurethequalityandvalidityoftheresearchanddevelopmentundertaken.Themainob-jectiveofIndependentTechnicalOversighthasbeentoperformanindependent andin-depthscienti"creviewofthephenomenologicalmodelsandexperimentsTuesday1 stMarch,2016:19:32,Page342of393 DRAFTPART4.RAIRESPONSES(ROUND2)developedandconductedfortheRisk-InformedGSI-191project.TheOver-sightteamsscopeofworkcoveredthecriticalreviewofallthedocuments relatedtothetechnicalareasoftheprojectsuchaslocation-speci"cLoss-of-Coolant-Accident(LOCA)frequencymodeling,Jetformationphysics,Debris generation,Debristransport,Strainerconventionalheadloss,Penetration,Re-actorthermo-hydraulic,Boronprecipitation,Uncertaintyquanti"cation,Chem-icalCoating,andProbabilisticRiskAnalysis.ThescopeoftheOversight didnotincludethereviewoftheCASAGrandesoftwaredevelopment,run,or process.TheIndependentOversightTeamisspeci"callyquali"edtopeerreview themethodologies,experimentsandcalculationsoftheSTPproject.TheOver-sightteammembershaveacademic(holdingPh.D.s)andindustryexperiencein bothprobabilisticanddeterministicdomains,andarecapableof(1)understand-ingprobabilisticmethods(e.g.,PRAanduncertaintyanalysis),(2)analyzing physicalandchemicalphenomena(e.g.,containmentcorrosiontests,strainer performancetests,andchemicaltests,thermo-hydraulicmodeling)(3) providingscienti"candpracticalfeedback,and(4)producingtechnically-sound andclearpeerreviewdocumentation.TheIndependentOversightteamprovidedtheanalysisteam(allotherven-dors)withwrittencommentsandallofthesecommentswereformallyresolved.

Thecommentsandresolutionsaredocumentedandavailable.Eachsetofcom-mentswasdevelopedbyoneortwooversightteammembersandreviewedby thethirdmemberoftheteambeforeitssubmittaltoSTPNOCandtherelated analysisvendor.Soteria/UIUCsapproachincludedbothactiveandpas-siveoversight.TwoPh.D.sofSoteria/UIUCinteractedandcollaboratedwith theanalysisteamstoprovidefeedbackandtoactiveoversightservices.Be-causeofthemultidisciplinaryandintegrativenatureoftheproject,members oftheoversightgroupwererequiredtoparticipateinmeetingsandthenfollow uponthediscussionsandissueswiththeothergroupmembersinvolvedinthe STPproject.Speci"careasofconcernandreviewwerealsodiscussedwithSo-teria/UIUCspassiveoversightmembers(bothseniorandjuniorexpertsinthe related"elds).TheSoteria/UIUCteamwasinvolvedinbothinformaland formaloversightactivitiesfortheSTPNOCRisk-Informedproject.Exam-plesofinformalactivitieswere(1)reviewingpre-meetingtechnicalreportsand documentsrelatedtoNRCpublicmeetingsandprovidingcomments,(2)provid-ingtechnicalsupportindevelopingACRSpresentations,and(3)participating inbrainstormingsessionsondiversetechnicaltopicalareaswiththerequired follow-upontheproposedideas.Someoftheformaloversightactivitiesincluded (1)participatinginweeklytechnicalteamteleconferencesandprovidingfeed-back,(2)participatinginmonthlytechnicalmeetingsandprovidingcomments, and(3)reviewingreportsanddocumentsanddevelopingwrittencommentsand follow-upresolutions.Inconclusion,theindependentoversighthasperformedconcurrentpeerre-viewsofdocuments,communicatedreviewcomments,hasfollowedupwithre-viewcommentresolutions,andhasanalyzedindustrylimitationsandregulatory concernstotempercomments.Thatis,theoversightteamhasprovidedreason-Tuesday1 stMarch,2016:19:32,Page343of393 DRAFTPART4.RAIRESPONSES(ROUND2)ablecommentsdirectedtowardsensuringacademicallydefensibleworkresults,butrecognizesthattheprojectwillgenerallyadoptexistingtechnologies(al-beitinnewways).BasedontheSoteria/UIUCteamsreview,theSTPNOC Risk-Informedprojectisanoutstandingblendofadvancedandconventional methodsthatnotonlycontributestowardstheclosureoftheGSI-191issues, butalsomakesasigni"cantcontributiontotheformalincorporationofun-derlyingphysicalfailuremechanismsofcertainpost-LOCAeventsintoProba-bilisticRiskAssessment(PRA).Soteria/UIUCoversightactivitiescon"dently concludedthattheSTPNOCRisk-Informedproject,havingawell-designedcom-binationofprobabilisticanddeterministicmethodologies,hasmadeimportant contributionstotheclosureofGSI-191issues.TheSoteria/UIUCteamiscon-

"dentinthescienti"cvalidityofmethodologies,experiments,andcalculations.

TheoversightteamcouldnotarriveatthesameconclusionregardingtheCASA GrandecodebecausethereviewoftheCASAGrandesoftwaredevelopment, run,andprocesswerenotincludedinthescopeoftheworkspeci"edforthe oversightteam.4.1.5Question1:TreatmentofUnanalyzedPlantConditionsSTPResponse:(Item1c,Page85)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.NUREG 1829pipebreakfrequenciesforthesmallestoftheunboundedbreaksisused directlyinatop-downapproachthatpreservestheexceedancefrequenciesto determineUseofRoverDdoesnotinvolvetheriskassessmentparame-tersthatarethesubjectsofthisRAI.4.1.6Question7:HumanReliabilityAnalysisSTPResponse:(Item1c,Page85)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7).RoverDdoesnotrelyonabetweenacleanplantandas designedplantanalysisinaclassicPRAsetting,nordoesitinvolveanHRA analysisasdescribedinthisRAI.Instead,RoverDrelegatesallscenariosthat resultin"nedebrismorethantestedamountstofailure.4.1.7Question1:KeyAssumptions/KeySourcesofUncertaintySTPResponse:(Item1g,Page86)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure andusesNUREG1829pipebreakfrequencyforthesmallestoftheunbounded breakstodetermineUseofRoverDdoesnotinvolveitemsa,b,andg,above.

Foritemsc,d,e,andf:Tuesday1 stMarch,2016:19:32,Page344of393 DRAFTPART4.RAIRESPONSES(ROUND2)c.Boronprecipitationwillbeaddressedinseparatesubmittal.d.PipebreakfrequenciesforthequantilesofthearithmeticandgeometricNUREG1829elicitationsareprovidedinAttachment7.e.RoverDusescore"beraccumulationbasedonmeasureddataand"owrateoftheECCSandcoreduringcoldlegbreakscenarios.Theeon core"beraccumulationofupperandlowerboundsofuncertaintyforpool concentrationand"ltrationareprovidedinAttachment7.f.TheuncertaintyofcontinuumbreakversusDEGBisshowninAttach-ment7.4.1.8Question1:ValidityofAssumptiononPumpCon"gurationsSTPResponse:(Item1,Page87)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.InRoverD, designbasispumpcon"gurationsareboundedbythedeterministictestdata.

STPNOCevaluatedtwoadditionalcases:threetrainoperationandsingletrain operation.Thethreetraincon"gurationisboundedbythedeterministictest.

However,thesingletrainoperationisnotboundedbythetest.Forthesingle traincase,theamountof"berisone-halfthetestedamount.UseofRoverDdoesnotinvolvequanti"cationoftheitemsintheRAIabove.4.1.9Question7:CASAGrandetoPRAInterfaceSTPResponse:(Item7,Page87)ForRoverD,thesmallestbreaksizethatisevaluatedforfailureis12.814inches(DEGBofthesurgeline).RoverDusesmeasuredtestdatainsteadof uncertaintyboundswhichmayresultinextremecasestobeevaluatedinCASA Grande.RoverDdoesnotrelyonaCASAGrandeevaluationforfailure.CASA Grandeexhaustivelysamplespotentialbreaklocationstodeterminethesmallest breaksizethatwillgeneratemore"brousdebristhanwasinthedeterministic

test.RoverDisdescribedinAttachment7.4.1.10Question1:FidelitybetweenRELAPSimulationsandCASA GrandeSTPResponse:(Item1,Page87)TheanalysisdiscussedinthisRAIwasoriginallyperformedinJuly2014,subsequenttothesubmittaloftheNovember2013LAR.Thequalityassurance fortheanalysisisconsistentwiththedescriptionoftheTAMUqualityprogram aspectsintheresponsetoRAI4intheprecedingProjectQualityAssurance RAIs.Theanalysisisincludedasanenclosuretothisattachment.AsdescribedinAttachment7,RoverDusesthermal-hydraulicanalysestoshowthatallsmallbreaksandallhotlegbreaksaresuccessbasedonPCT.

RoverDdoesnotrelyon"delitywithCASAGrandeforsuccesscriteria.Tuesday1 stMarch,2016:19:32,Page345of393 DRAFTPART4.RAIRESPONSES(ROUND2)UseofRoverDappliesthedeterministictestingtoevaluatebypassandblock-age.4.1.11Question1:State-of-KnowledgeCorrelationSTPResponse:(Item1,Page88)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandecoupledtothePRAtogeneratecon-ditionalfailureprobabilities.RoverDisalesscomplexapproachthatrelegates breaksizesthatgenerateandtransportdebristhatisnotboundedbydeterminis-tictestingtofailureandusesNUREG1829pipebreakfrequencyforthesmallest oftheunboundedbreakstodetermineTheapplicationofRoverDelim-inatestheneedtoaccountforstate-of-knowledgeforLOCAfrequenciessince STPisonlyapplyingLOCAfrequencyasdeterminedfromNUREG1829.4.1.12Question1:SelectionofJohnsonParametersSTPResponse:(Item1,Page88)RoverDevaluationofDeltaCDFandDeltaLERFfrequenciesarenotde-velopedfromsamplingaJohnsondistribution.Instead,theyaretakendirectlyfromtheNUREG1829tableforthegeometricmeanaggregation.InSection4.3 ofAttachment7,thequantilesforboththearithmeticandgeometricaggrega-tionareshownforallquantilesdevelopedfromtheNUREG1829elicitation.

TheSTPPRAModelofRecorddeterminationofplantaverageCDFandLERF isunchangedinRoverD.4.2ML15091A440,EMCBResponses4.2.1Question2STPResponse:(Item2,Page89)Toclarifythepreviousresponse:

• Case1correspondstothemaximumdebrisloadingatthemaximumtem-perature.*Case2correspondstothemaximumdebrisloadingattheminimumtem-perature.Therefore,theanalysisboundsallpossibledebrisloadingandtemperaturecombinations.4.3ML15091A440,ESGBResponses4.3.1Question23:ChemicalSTPResponse:(Item23,Page89)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemicalTuesday1 stMarch,2016:19:32,Page346of393 DRAFTPART4.RAIRESPONSES(ROUND2)Consequently,thesconclusioniscorrect,albeitforadtrea-son.4.3.2Question24:ChemicalSTPResponse:(Item24d,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.4.3.3Question25:ChemicalSTPResponse:(Item25d,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerateandtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.4.3.4Question26:ChemicalSTPResponse:(Item26c,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL*corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.RoverD doesnotrelyonthetestdatafromSouthernNuclearCompany.4.3.5Question27:ChemicalSTPResponse:(Item27,Page91)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

Chemicalareaccountedforintheplant-speci"cdeterministictesting.4.3.6[ML15091A440]Question28:ChemicalSTPResponse:(Item28,Page91)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerateTuesday1 stMarch,2016:19:32,Page347of393 DRAFTPART4.RAIRESPONSES(ROUND2)andtransportdebristhatisnotboundedbydeterministictestingtofailure.Chemicalareaccountedforintheplant-speci"cdeterministictestingand STPnolongerintendstoapplyacorrelationtodeterminechemical4.3.7Question29:ChemicalSTPResponse:(Item29,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforchemicalChem-icalincludingzinc,areaccountedforintheplant-speci"cdeterministic

testing.4.3.8Question30:ChemicalSTPResponse:(Item30,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical areaccountedforintheplant-speci"cdeterministictesting.4.3.9Question31:ChemicalSTPResponse:(Item31,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical areaccountedforintheplant-speci"cdeterministictesting.AsdescribedinAttachment7,thetestingwasbasedonanassumptionoftwotrainsoperating.Inaddition,RoverDevaluatesthesingle-traincasewhere thedeterministicsuccesscriterionishalfofthetwotrainoperatingcasedebris.4.3.10Question32:ChemicalSTPResponse:(Item32,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical includingpresumedradiationareconsideredtobeaccountedfor intheconservatismofplant-speci"cdeterministictesting,whichisperformed perWCAP-16530.RAIresponsesintheNRCreviewedWCAP-16530-NP-Ain-dicatethatradiolysisandeofradioactivespecieswouldnotbeexpected tohaveasigni"cant4.3.11Question33:ChemicalSTPResponse:(Item33,Page93)Tuesday1 stMarch,2016:19:32,Page348of393 DRAFTPART4.RAIRESPONSES(ROUND2)HistoricalinformationisavailableconcerningCRUDreleasefrompre-outageCRUDcleanupperformance.CRUDreleasedataduringforcedoutages,includ-ingreactortrips,isboundedbyCRUDburstcleanupdataduringrefueling

outages.TheoutagereleasedatapertaintoreleasesfollowingattemptstoremoveCRUDfromsurfacesusingaggressivechemicalcleaningproductssuchashy-drogenperoxidetopurposelyremoveasmuchCRUDaspossiblefromtheplant priortooutagework(primarilyforALARAinterest).ThemeasurementofCRUDmassisbasedelementalanalysis,notactualweight.ThehistoryoftheweightofCRUDremoved(usingelementalanalysis) fromSTPduringoutageCRUDremovalsisshowninthe"gurebelow.The CRUDmeasurementsareconsistentwithindustrypracticeforthisperformance

indicator.The"gureshowstheamountofNiremoved,notallmetals.However,NiisthepredominantcontributortotheCRUDinventory.The"gureshowsthe totalamountofCRUDremovedduringthecrudburstevolutionandcleanup.

TheCRUDreleasedismostlysolubleorverysmallparticulate(<1micron)insize.ShownaswellistheactivityofCo58whichhelpsgiveanunderstanding ofhowmuchoftheCRUDiscomingfromthefuel.STPfurtherperformsfuel ultrasoniccleaningwhichisanevenmoreaggressivecleaningtechniquethan chemicalcleaning,removingsubstantialamountsofCRUDfromreloadfuel.

Thisinventoryreductionisnotshownonthegraph.Asthegraphbelowshows,recentCRUDamountsarelessthan2lbsuchthatCRUDisnotasigni"cantcontributortothedebrisinventory.4.3.12Question34:ChemicalSTPResponse:(Item34,Page93)Figure3showsweightedmeanquantitiesdeterminedforlargebreaksfromaCASAGrandeplantstateCase.TheCASAGrandequantitiesarebasedona 17DZOI.Table2showstestedstrainer"berquantitiesgeneratedfromaCAD modelmacrousinga7DZOIfromaspeci"clocation(HotLeg).Tuesday1 stMarch,2016:19:32,Page349of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.3.13Question8:CoatingsSTPResponse:(Item8,Page93)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverDdoes notrelyonacorrelationormodeltoaccountforcoatings.NotethatMarinite hasbeenremovedfromtheSTPcontainmentbuildingsandthetestincluded approximately183lbmofpowderedMariniteboardwhichisalmosttwicethe amountofepoxyintroducedaschips.TheMarinitecanreasonablybeconsidered tomakeupfortheunquali"edepoxy.4.3.14Question9:CoatingsSTPResponse:(Item9,Page93)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforcoatings.Coatingsareac-countedforintheplant-speci"cdeterministictesting.Thequantityofinorganic zincintheSTPplant-speci"ctestingwasbasedon5DZOI.4.3.15Question10:CoatingsSTPResponse:(Item10,Page94)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforcoatings.Coatingsare accountedforintheplant-speci"cdeterministictestingwhichdoesnotrelyon failuretiming.4.4ML15091A440,SCVBResponses4.4.1Question10STPResponse:(Item10c,Page96)STPNOCwilladdareferencetotheUFSARsectionsreferencedabovetoprovideabriefsummaryofthedesignbasisandreferencetothedetailedde-scriptionthatwillbeprovidedinAppendix6AtotheUFSAR.Thebriefsummarywillbewordedsimilartothedescriptionbelow,usingtheappropriatefunction/GDCinthebrackets:TheLicensingBasisfor[containmentheatremoval]withregardtoofdebrisonemergencysumpstrainerstotheextentthatthestrainerssupportthe[CSSorECCS]elementofthe[containmentheatremovalfunction],isarisk-informedanalysisthatshowsthereisahighprobabilitythat[CSSorECCS]can performitsdesignbasisfunctionsbasedonplant-speci"cprototypicaltestingTuesday1 stMarch,2016:19:32,Page350of393 DRAFTPART4.RAIRESPONSES(ROUND2)usingdeterministicassumptionsthatprovidesafetymarginanddefense-in-depthandthattheriskfrombreaksthatcouldgeneratedebristhatisnotboundedby thetestingisverysmallinaccordancewiththecriteriaofRG1.174.Theconservatisminthetestingissigni"cantenoughthatusingrealisticanalysisandtesting,itisnotlikelythatdebrisonthestraineroron thecorewouldresultinfueldamage.Inaddition,theofdebrisdonot compromisecontainmentintegritywhichensuresdefenseindepthispreserved evenintheunlikelyeventthecoreiscompromised.TheSTPRiskoverDeterministic(RoverD)methodologywasusedtoevalu-atetheeofdebris.RoverDrelegatesbreaksizesthatgenerateandtransport debristhatisnotboundedbydeterministictestingtofailure(coredamage).It thenappliestheNUREG1829pipebreakfrequencyforthesmallestunbounded breakstodeterminetheincreaseincoredamagefrequency.Theincreaseiscom-paredtothecriteriainRG1.174.Theanalysisshowsthattheriskfromthe unboundedbreaksisverysmall,asde"nedbyRG1.174.Anexemptionto[GDC 38]hasbeenapprovedtoallowapplicationoftherisk-informedanalysisinstead ofthesinglefailureassumptionrequiredby[GDC38].Theexemptionapplies tothescopeofbreaksthatgenerateandtransportdebrisnotboundedbythe deterministictesting.DetailsofthedesignbasisfortheofdebrisonthefunctionoftheemergencysumpstrainersisprovidedinUFSARAppendix6A.STPNOCwillrevisetheUFSARChapter3evaluationsagainstCriteria35,38,and41(Plannedchangesareunderlined):3.1.2.4.6.1EvaluationAgainstCriterion35TheECCSisprovidedtocopewithanyLOCAintheplantdesignbasis.Abundantcoolingwaterisavailable inanemergencytotransferheatfromthecoreataratettomaintain thecoreinacoolablegeometryandtoassurethatcladmetal/waterreactionis limitedtolessthan1percent.Exceptfortheeofdebris,adequatedesign provisionsaremadetoassureperformanceoftherequiredsafetyfunctionseven withasinglefailure.TheSTPRiskoverDeterministic(RoverD)methodology wasusedtoevaluatetheeofdebris.RoverDrelegatesbreaksizesthat generateandtransportdebristhatisnotboundedbydeterministictestingto failure(coredamage).ItthenappliestheNUREG1829pipebreakfrequency forthesmallestunboundedbreakstodeterminetheincreaseincoredamage frequency.TheincreaseiscomparedtothecriteriainRG1.174.Theanalysis showsthattheriskfromtheunboundedbreaksisverysmall,asde"nedbyRG 1.174.AnexemptiontoGDC35hasbeenapprovedtoallowapplicationofthe risk-informedanalysisinsteadofthesinglefailureassumptionrequiredbyGDC 35.Theexemptionappliestothescopeofbreaksthatgenerateandtransport debrisnotboundedbythedeterministictesting.Detailsoftheconditionsfor theexemptionareincludedinAppendix6A.DetailsofthecapabilityofthesystemsareincludedinSection6.3.Aneval-uationoftheadequacyofthesystemfunctionsisincludedinChapter15.Per-formanceevaluationshavebeenconductedinaccordancewith10CFR50.46and 10CFR50AppendixK.Tuesday1 stMarch,2016:19:32,Page351of393 DRAFTPART4.RAIRESPONSES(ROUND2)3.1.2.4.9.1EvaluationAgainstCriterion38TheCHRSconsistsoftheCSS,theReactorContainmentFanCooler(RCFC)Subsystemandtheresidual heatremoval(RHR)heatexchangers.TheCHRSactsinconjunctionwiththe SafetyInjectionSystemtoremoveheatfromtheContainment.TheCHRSis designedtoaccomplishthefollowingfunctionsintheunlikelyeventofaLOCA:

torapidlycondensethesteamwithintheContainmentinordertopreventover pressurizationduringblowdownoftheRCS;andtoprovidelong-termcontinuous heatremovalfromtheContainment.Initially,theCSSandthehigh-andlow-headsafetyinjection(HHSIandLHSI)pumpstakesuctionfromtherefuelingwaterstoragetank(RWST).Dur-ingtherecirculationphase,theCSSandtheHHSIandLHSIpumpstakesuction fromtheContainmentemergencysumps.TheCHRSisdividedintothreetrains.

Eachtrainissizedtoremove50percentofthesystemdesignheatloadatthe startofrecirculation.EachtrainoftheCHRSissuppliedpowerfromaseparate independentClass1Ebus.Theredundancyandcapabilityoftheand EmergencyPowerSystemsarepresentedintheevaluationagainstCriterion17.

Redundantsystemtrainsandemergencydieselpowersuppliesprovideassurance thatsystemsafetyfunctionscanbeaccomplished.AnexemptiontoGDC38has beenapprovedtoallowapplicationofarisk-informedanalysisinsteadofthesin-glefailureassumptionrequiredbyGDC38,toaddresstheofdebris.The STPRiskoverDeterministic(RoverD)methodologywasusedtoevaluatethe ofdebris.RoverDrelegatesbreaksizesthatgenerateandtransportdebris thatisnotboundedbydeterministictestingtofailure(coredamage).Itthenap-pliestheNUREG1829pipebreakfrequencyforthesmallestunboundedbreaks todeterminetheincreaseincoredamagefrequency.Theincreaseiscomparedto thecriteriainRG1.174.Theanalysisshowsthattheriskfromtheunbounded breaksisverysmall,asde"nedbyRG1.174.Theexemptionappliestothescope ofbreaksthatgenerateandtransportdebrisnotboundedbythedeterministic testing.DetailsoftheconditionsfortheexemptionareincludedinAppendix

6A.Forfurtherdiscussion,seethefollowingsectionsoftheUFSAR:

ResidualHeatRemovalSystem5.4.7DesignforDebrisApp.6ACon-tainmentSystems6.2EngineeredSafetyFeaturesActuationSystem7.3Onsite PowerSystem8.3AccidentAnalysis15.03.1.2.4.12.1EvaluationAgainstCriterion41TheCSSisprovidedtore-ducetheconcentrationandquantityof"ssionproductsintheContainment atmospherefollowingaLOCA.Per10CFR50.44,hydrogenrecombinersareno longerrequiredfordesignbasisaccidents.TheequilibriumsumppHismaintainedbytrisodiumphosphate(TSP)con-tainedinbasketsonthecontainment"oor.TheinitialCSSwaterandspilledRCS waterdissolvestheTSPintothecontainmentsumpallowingrecirculationofthe alkaline"uid.Eachunitisequippedwiththree50-percentspraytrainstaking suctionfromtheContainmentsump.EachContainmentspraytrainissupplied powerfromaseparatebus.Eachbusisconnectedtoboththeandthe StandbyPowerSupplySystems.ThisassuresthatforOnsiteorforElec-Tuesday1 stMarch,2016:19:32,Page352of393 DRAFTPART4.RAIRESPONSES(ROUND2)tricalPowerSystemfailure,theirsafetyfunction(exceptfortheconsiderationofdebriscanbeaccomplished,assumingasinglefailure.Anexemption toGDC41hasbeenapprovedtoallowapplicationofarisk-informedanalysis insteadofthesinglefailureassumptionrequiredbyGDC41,toaddresstheef-fectsofdebrisontheCSSfunction.TheSTPRiskoverDeterministic(RoverD) methodologywasusedtoevaluatetheeofdebris.RoverDrelegatesbreak sizesthatgenerateandtransportdebristhatisnotboundedbydeterministic testingtofailure(coredamage).ItthenappliestheNUREG1829pipebreak frequencyfortheunboundedbreakstodeterminetheincreaseincoredamage frequency.TheincreaseiscomparedtothecriteriainRG1.174.Theanalysis showsthattheriskfromtheunboundedbreaksisverysmall,asde"nedbyRG 1.174.Theexemptionappliestothescopeofbreaksthatgenerateandtransport debrisnotboundedbythedeterministictesting.Detailsoftheconditionsfor theexemptionareincludedinAppendix6A.Post-accidentcombustiblegascontrolisassuredbytheuseoftheSupple-mentaryContainmentPurgeSubsystem.Forfurtherdiscussion,seethefollowingsectionsoftheUFSAR:ContainmentSystems6.2ContainmentSpraySystemIodineRemoval6.5.2 DesignforDebrisApp.6A ContainmentHydrogenSamplingSystem7.6.5 ContainmentHVACSystem9.4.54.4.2ML15246A128,Question11STPResponse:(Item11,Page96)PerSTPUFSARChapter3.1.2.4.9.1,GDC38ismetbyRCFCworkinginconjunctionwithCSSandECCS(LHSIthroughtheRHRheatexchangers)to removeheatfromthecontainment.Thescopeoftheexemptionwillapplyalso totheECCSbecauseofitsrelianceonthesumpstrainers.OnlytheCSSandthe ECCSfunctionsaredirectlybydebrissincetheyarethecontainment heatremovalfunctionsthatrelyonthesumpstrainersintherecirculationphase.

TheRCFCcoolingheatsinkisindependentNoexemptionisproposedtoapplytothesupportsystemsfortheCSSortheECCS.Theproposedexemptionsapplyonlyfortheofdebris.Noneofthe CSSorECCSsupportsystemsrelyontheECCSemergencysumpsandstrainers toperformtheirsupportfunctionandthuswillnotbebydebris.4.4.3ML15246A128,Question12(1)STPResponse:(Item(1),Page96)STPNOCproposesthattheexemptionwouldapplyforthisrequirementforthoseLOCAbreaksthatcouldgenerateanamountofdebristhatisnotbounded bythedeterministictesting.CurrentSTPdesignbasiscalculationsarebasedon RCFCfunctioninginconjunctionwithCSSandECCS,whichcanbe bydebris.Tuesday1 stMarch,2016:19:32,Page353of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.4ML15246A128,Question12(2)STPResponse:(Item(2),Page96)Usingcurrentdeterministicassumptions,STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupport theCSSandECCSfunctionfortheofdebrisproducedbyLOCAbreaks thatcangeneratedebristhatisnotboundedbyplant-speci"cdeterministic testing,asdescribedinRoverD.4.4.5ML15246A128,Question12(3)STPResponse:(Item(3),Page96)STPdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformanysupport functionforemergencypowerforCSSorECCSintheeventofaLOOP.4.4.6ML15246A128,Question12(4)STPResponse:(Item(4),Page96)TheSTPapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsinglefailure requiredbytheGDC.Inaccordancewiththesinglefailurecriteria,asingle occurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoallthree emergencysumpstrainers.STPNOCrequestsexemptiontothisrequirement forthedebrisfromLOCAbreaksthatcangeneratedebristhatisnot boundedbydeterministictestingtoallowtheapplicationofarisk-informed analysisthatshowsthattheriskfromdebrisisverylow,inaccordance withtheRG1.174criteria,asdescribedinRoverD.4.4.7ML15246A128,Question12(4)a.STPResponse:(Item12a,Page96)TheSTPNOCapplicationspeci"callyrequestsexemptiontoItem(4),whichhasadirectlinktoItems(1)and(2).NoexemptiontoItem(3),LOOP,is

needed.4.4.8ML15246A128,Question12(4)b.STPResponse:(Item12b,Page96)ThescopeoftheexemptionappliesforLOCAbreaksizesandlocationsthatpotentiallygeneratedebristhatexceedsthequantityboundedbySTP plant-speci"ctesting.Thatscopeisgenerallydescribedasbreakslargerthan approximately12.8"IDinlocationswhereastamountof"brousdebris canbegeneratedandtransportedtothesump.Forty-"ve(45)weldlocations havecurrentlybeenidenti"edonthepressurizersurgelineandRCSmainloop piping.Tominimizethepotentialthatalateranalysiscouldcausethespeci"c locationstochange,therequestedexemptionisbasedonthebreaksabilityto generatettransportabledebris,asdescribedinRoverD.Thebasisfortheexemptionisdescribedintheresponsetothe"rstRAIabove.Tuesday1 stMarch,2016:19:32,Page354of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.9ML15246A128,Question13STPResponse:(Item13,Page97)NoexemptionisproposedtoapplytothesupportsystemsfortheCSS.Theproposedexemptionsapplyonlyfortheeofdebris.NoneoftheCSS supportsystemsrelyontheECCSemergencysumpsandstrainerstoperform theirsupportfunctionandthuswillnotbebydebris.4.4.10ML15246A128,Question14(1)STPResponse:(Item(1),Page97)NoexemptionisproposedtoapplytothesupportsystemsfortheCSS.Theproposedexemptionsapplyonlyfortheeofdebris.NoneoftheCSS supportsystemsrelyontheECCSemergencysumpsandstrainerstoperform theirsupportfunctionandthuswillnotbebydebris.4.4.11ML15246A128,Question14(2)STPResponse:(Item(2),Page97)Usingdeterministicassumptions,STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupporttheCSS functionfortheofdebrisproducedbyLOCAbreaksthatcangenerate debristhatisnotboundedbyplant-speci"cdeterministictesting,asdescribed inRoverD.4.4.12ML15246A128,Question14(3)STPResponse:(Item(3),Page97)STPNOCdoesnotproposeexemptiontothisrequirementsincethesefunc-tionsarenotbydebris.4.4.13ML15246A128,Question14(4)STPResponse:(Item(4),Page97)STPNOCdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformany supportfunctionforemergencypowerforCSSintheeventofaLOOP.4.4.14ML15246A128,Question14(5)STPResponse:(Item(5),Page97)TheSTPNOCapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsingle failurerequiredbytheGDC.Inaccordancewiththesinglefailurecriteria,a singleoccurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoall threeemergencysumpstrainers.STPNOCrequestsexemptiontothisrequire-menttoallowtheapplicationofarisk-informedanalysisthatshowsthatthe riskfromdebrisisverylow,inaccordancewiththeRG1.174criteria.4.4.15ML15246A128,Question14(5)(a)STPResponse:(Item(a),Page97)Response:Seeresponseto(b)below.Tuesday1 stMarch,2016:19:32,Page355of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.16ML15246A128,Question14(5)(b)STPResponse:(Item(b),Page98)STPNOCrequestspartialexemption;i.e.,onlyItem2above.Asstatedabove,STPNOCsanalysisandtestingdoesnotassurethattheemergencysump strainerswillbeavailabletosupporttheCSSfunctionfortheofdebris producedbyLOCAsthatgenerateandtransportdebristhatisnotboundedby testing,asdescribedinRoverD.Forty-"ve(45)weldlocationshavecurrently beenidenti"edonthepressurizersurgelineandRCSmainlooppiping.Tomin-imizethepotentialthatalateranalysiscouldcausethespeci"clocationsto change,therequestedexemptionisbasedonthebreaksabilitytogenerate ttransportabledebris,asdescribedinRoverD.4.4.17ML15246A128,Question15STPResponse:(Item15,Page98)NoexemptionisneededforsystemsthatsupportECCS.Thedebrisonlysystemsthatrelyontheemergencysumpstrainersasasupportsystem.

NoneofthesupportsystemsrequiredforECCSoperabilitysuchascooling water,instrumentationandcontrol,andnormalandemergencypowerrelyonthe emergencysumpstrainerstoperformtheirfunction.Therequestedexemption forGDC35theECCSsupportsystems(AndtherequestedexemptionsforGDC 38and41donotapplytotheCSSsupportsystems.)4.4.18ML15246A128,Question16(1)STPResponse:(Item(1),Page98)TheSTPNOCproposedexemptionwouldapplyforthisfunctionalrequire-ment.AsdiscussedinpriorresponsesanddescribedintheRoverDmethodology, thefunctionoftheECCSemergencysumpisassumedtofailfordebristhatex-ceedstheamountinthedeterministictesting.Undertheseassumptions,failure ofthesumpandstrainerswillresultinlossofcoolingtothecore.4.4.19ML15246A128,Question16(2)STPResponse:(Item(2),Page98)STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupporttheECCSfunctionfortheofdebris producedbyLOCAsthatgenerateandtransportdebristhatisnotboundedby testing,asdescribedinRoverD.Consequently,STPNOCisrequestingexemption forthatscopeofLOCAsthatwillproduceandtransporttdebristo exceedthedebrisformingthebasisforthedeterministictestingdescribedin RoverD.4.4.20ML15246A128,Question16(3)STPResponse:(Item(3),Page98)STPNOCdoesnotproposeexemptiontothisrequirementsincetheseECCSsupportfunctionsarenotbydebris.4.4.21ML15246A128,Question16(4)STPResponse:(Item(4),Page98)Tuesday1 stMarch,2016:19:32,Page356of393 DRAFTPART4.RAIRESPONSES(ROUND2)STPNOCdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformany supportfunctionforemergencypowerforECCSintheeventofaLOOP.4.4.22ML15246A128,Question16(5)STPResponse:(Item(5),Page98)TheSTPNOCapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsingle failurerequiredbytheGDC.Inaccordancewiththesinglefailurecriteria,a singleoccurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoall threeemergencysumpstrainers.STPNOCrequestsexemptiontothisrequire-mentforthedebrisfromLOCAbreaksthatcangeneratedebristhatis notboundedbydeterministictestingtoallowtheapplicationofarisk-informed analysisthatshowsthattheriskfromdebrisisverylow,inaccordance withtheRG1.174criteria,asdescribedinRoverD.4.4.23ML15246A128,Question16(5)(a)STPResponse:(Item(a),Page98)Seeresponseto(b).4.4.24ML15246A128,Question16(5)(b)STPResponse:(Item(b),Page99)STPNOCisrequestingapartialexemptionasdiscussedintheresponsesabove.TheproposedexemptiontoGDC35wouldapplytoItems(1),(2),and (5)forthescopeofbreaksdescribedin(2).Thetechnicalbasisisdescribedin theRoverDmethodology(Attachment7).4.4.25ML15246A128,Question17STPResponse:(Item17,Page99)STPwillrespondtothisRAIinaseparatesubmittal.4.4.26ML15246A128,Question18(a)(b)(c)(d)STPResponse:(Item(d),Page100)TheRoverDmethodologydoesnotuseRELAP5-3DorMELCORforcon-tainmentconditions.4.5ML15091A440,SNPBResponses4.5.1Question6STPResponse:(Item1,Page101)Fullblockageanalysesareperformedprimarilytoshowadequatecooling"owintheextremecasewhereallthenormal"owpathsareblockedbydebris.

Basedonmeasurementsof"ltrationoftheSTPstrainerdesign,there istdebrispenetratingthestrainerstoeelyblockthenormal"ow channels.IntheRoverDanalysisitisshownthatverylittle"berarrivesonthe coreincoldlegbreaks.Theamountsaresosmallthatitisunlikelymixing"owsTuesday1 stMarch,2016:19:32,Page357of393 DRAFTPART4.RAIRESPONSES(ROUND2)willbeimpeded.ThereforeSTPNOChasconcludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.2Question7STPResponse:(Item2,Page102)Fullblockageanalyseswithasmallunblockedchannelareperformedprimar-ilytoshowthemargintoadequatecooling"owintheextremecasewhereallthe normal"owpathsareblockedbydebris.Basedonmeasurementsof"ltration oftheSTPstrainerdesign,thereistdebrispenetratingthe strainerstoeelyblockthenormal"owchannels.IntheRoverDanalysisit isshownthatverylittle"berarrivesonthecoreincoldlegbreaks.Theamounts aresosmallthatitisunlikelymixing"owswillbeimpeded.ThereforeSTPNOC hasconcludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.3Question8STPResponse:(Item3,Page102)Basedonmeasurementsof"ltrationoftheSTPstrainerdesign,thereisitdebrispenetratingthestrainerstoeelyblockthenor-mal"owchannels.IntheRoverDanalysisitisshownthatverylittle"berarrives onthecoreincoldlegbreaks.Theamountsaresosmallthatitisunlikelymix-ing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.4.5.4Question9STPResponse:(Item4,Page102)TheRoverDanalysisreliesonthecurrentUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatverylittle"berarrivesonthecoreincoldlegbreaks.Theamountsareso smallthatitisunlikelymixing"owswillbeimpeded.ThereforeSTPNOChas concludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.5Question10STPResponse:(Item5,Page103)TheRoverDanalysisreliesontheUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatvery little"berarrivesonthecore.Theamountsaresosmallthatitisunlikely mixing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.Insummary,STPNOCsevaluationshowsthatthesmallamountsof"berthatmayaccumulatewouldnotcorecoolingorBAP,suchthattheywould notclosingGL2004-02.STPNOCsanalysisissimilarinapproachand conclusionstohowtheNRCaddressedBAPintheSEtoWCAP16793-NP.4.6ML15091A440,SSIBResponses4.6.1Question43STPResponse:(Item43,Page103)Tuesday1 stMarch,2016:19:32,Page358of393 DRAFTPART4.RAIRESPONSES(ROUND2)AnapplicationwasmadetowithholdthisinformationfrompublicinspectionaspartofaletterdatedMay15,2014(ADAMSAccessionNo.ML14149A353) asitappearedinCASAGrandeinput"lesthatweresubmittedtotheNRCfor review.Permissiontowithholdthedocumentpursuantto10CFR2.390(b)(5) andSection103(b)oftheAtomicEnergyActof1954,asamended,wasgranted onML14092A557datedJune4,2014.Assuch,Reference46,wasandis,re-spectfullynotincludedinthesubmittal.ThemethodologyusedbySTPNOC(LAREncl.4-3Rev.2)forsizedistri-butionsofLDFG(%ofeachsizecategory)destroyedbyapostulatedZOI,has beenpreviouslyreviewedbytheNRCintheIndianPointEnergyCenterCor-rectiveActionsforGenericLetter2004-2document(i.).IntheIndianPoint EnergyCenterCorrectiveActionsdocument,NRCreviewersstatedThe foundthisapproachforNukon RandTemp-Mat TMtobeacceptablebecauseitisconsistentwithormoreprecisethantheDDTSevaluations,whendiscussing themethodologyusedforsizedistributionsofLDFGgeneratedwithintheZOI; thissamemethodologywasimplementedforSTP.i.ML082050433.IndianPointEnergyCenterCorrectiveActionsforGenericLetter2004-02,2008.4.6.2Question44STPResponse:(Item44,Page103)Themethodologyusedtoestimatethetransportof"brousdebrisfromallpotentialbreaklocationsisrealisticandconservative,asshowninthediscussion thatfollows.Table2ofRound1,SSIB-III-4ResponseillustratesametricofLDFGcon-gestionpercentforeachbreakcategory.Thiscongestionmetric(Round1,SSIB-III-4Response)wasasupplementalmetrictosupporttheimplementationof thesteamgeneratortransportfractionforallbreaksinLAREncl.4-3.Thecon-gestionmetricwasnotusedtodeterminethedebristransporttothestrainer (referredtoastransportfractions).Inessence,LDFGcongestionmaynotbe themetricthatdominatesthelikelihoodofdebrisreachingthestrainerbased onbreaklocation,andinRound1,SSIB-III-4,responseitwasintendedasa secondary,supplementalobservation.Table1below,(alsoTable1ofRound1,SSIB-III-4)illustratesthetotaltransportfractionsfromthe"velargebreakscenariosexaminedinthedebris transportcalculation(i,Section6.0,Table6.0.86.0.13,Pg.159164).Note thatthesearetheresultsofthemaximumtotaltransportvalues.WiththesoleexceptionofbreaksoccurringbelowtheSGCompartment,theoveralltransportfractionsassociatedwithIndividualLDFGandSmallLDFG forbreaksintheSGCompartmentareequaltoorgreaterthantheoverall transportfractionsassociatedwithIndividualLDFGandSmallLDFGforother breaklocations.At"rstglance,thismayimplythatusingoveralltransport fractionsassociatedwithbreaksintheSGCompartmentforbreaksthatoccur belowtheSGCompartmentforIndividualLDFGandSmallLDFGwouldyield anun-conservativeassessmentoftheee.g.,strainerheadloss,ofbreaksTuesday1 stMarch,2016:19:32,Page359of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:OverallDebrisTransportFractionsBreakLocationRegionIndividualLDFGSmallLDFGLargeLDFGLatentSGCompartment99%42%1%95%BelowSGCompartment99%60%7%95%

PressurizerCompartment97%31%1%91%

PressurizerSurgeLine97%30%1%91%

RHRCompartment97%30%2%91%

Annulus97%33%8%91%thatoccurbelowtheSGCompartment.However,only278ft 3ofLDFGexistsbelowtheSGCompartment(iii.).EvenifallLDFGbelowtheSGCompartmentfailedandtransported,i.e.,the overalltransportfractionwas1.0,therewouldnotbeenoughdebristocause failureinafullrisk-informedevaluation,(seeSSIB-45fTable3whichgivesthe minimumamountof"bergeneratedthatcausesaCASAGrandescenariotogotofailureof325ft 3fortheallpumpsactivebaseCase1).Therefore,usinganapparentlynon-conservativeoveralltransportfractionforbreaksoccurring belowtheSGCompartmentisofnopracticalrelevance.Ontheotherhand,using overalltransportfractionsforIndividualLDFGandSmallLDFGassociatedwith breaksintheSGCompartmentforallbreaklocationsisconservativebecause(1) thetransportfractionsforIndividualLDFGandSmallLDFGforbreaksinthe SGCompartmentwereconservativelyderived,and(2),transportfractionsfor Individual"ne"berLDFGandSmallLDFGforbreaksintheSGCompartment exceedthoseassociatedwithotherbreaklocations;seeTable1.Table1showsthattransportfractionsforLargeFiberassociatedwithbreaksintheRHRCompartmentandAnnulusexceedthetransportfractionforLarge FiberassociatedwithbreaksintheSGCompartment.However,themaximum total"ber,includingallsizes,associatedwiththebreaksintheRHRCompart-mentandAnnulusare299.4ft 3and79.4ft 3,respectively.SimilartothecaseaboveforbreaksthatoccurbelowtheSGCompartment,evenifallLDFGasso-ciatedwiththebreaksintheRHRCompartmentandAnnulusfailedandtrans-ported,i.e.,theoveralltransportfractionwas1.0,therewouldnotbeenough debristocausefailureinafullrisk-informedevaluation.Therefore,usinganap-parentlynon-conservativeoveralltransportfractionforbreaksoccurringinthe RHRCompartmentandAnnulusisofnopracticalrelevance.Inconclusion,usingtransportfractionsassociatedwithbreaksintheSGCompartmentforbreaksinallregionsofcontainmentresultsinadequateand conservativeestimatesoftransportforallcaseswheretheacceptancecriteria forsumpheadlossmaybechallenged.Thefollowingdiscussionillustratesthatthemethodologyusedtodeterminetransportfractionsresultedinrealisticandconservativetransportfractions.ThedebristransportfractionswerecalculatedinLAREncl.4-3,Reference23.AsstatedintheresponsestoRound1RAIs,thiscalculationwasrevisedTuesday1 stMarch,2016:19:32,Page360of393 DRAFTPART4.RAIRESPONSES(ROUND2)toRevision3(i.)whichissummarizedbelowwhilehighlightingconservatismsandassumptions.Debristransportistheestimationofthefractionofdebris thatistransportedfromdebrissources(breaklocations)tothesumpstrainers.

Sincerisk-informedmethodologyexaminesnumerousweldsincontainment,the transportfractionsaredeterminedasafunctionofbreaklocationasspeci"ed below.*Breaksinthesteamgeneratorcompartments

• Breaksinthereactorcavity

• Breaksinsidesecondaryshieldwall(ISSW)beneathsteamgeneratorcom-partments*Breaksinthepressurizercompartment

• Breaksoutsidesecondaryshieldwallinthepressurizersurgeline

• Breaksoutsidesecondaryshieldwallintheresidualheadremoval(RHR)compartments

• BreaksoutsidesecondaryshieldwallintheannulusDebristransportissubdividedinto"vemodesorphaseswhichare:

• Blowdowntransportthetransportofdebrisbythebreakjet.AsstatedintheRound2,SSIB-III-6aresponse,blowdowndoesnotcapturedebris (orreducetheamountofdebrisavailablefortransport).Blowdownesti-matesthelocationofdebriswhileaccountingforobstructionsthatcause debristoberetainedinthecompartmentofbreakorigin.Thisblowdown phenomenonisreferredtoascaptureinthisRAI,butitdoesnotre-ducetheamountofdebrisavailablefortransportinsubsequenttransport modes.-Blowdownwasindependentlydeterminedforeachbreaklocationduetothevarianceofthe"owobstructions.

-Blowdowntransportsdebristouppercontainment,thecontainmentpool,anddebrisretainedinthecompartmentofbreakoriginwhich iscalculatedby:Transporttouppercontainment-thevolumeratioofuppercon-tainmenttoallofcontainmentandisadjustedbythedebristhat willbecapturedby"owobstructions.Transporttothecontainmentpool-thevolumeratiooflowercontainmenttoallofcontainmentandisadjustedbythedebris thatwillbecapturedby"owobstructions.Debrisretainedinthecompartment-oneminusthedebristrans-portedtouppercontainmentminusthedebristransportedtothe containmentpool.Tuesday1 stMarch,2016:19:32,Page361of393 DRAFTPART4.RAIRESPONSES(ROUND2)

-Table2displaystheblowdowncapturefractionsoftheDDTSandtheimplementedcapturefractionsforthedebristransportcalcula-

tion.Table2:BlowdownCaptureFractionsCEESICapturePercentageforWettedTestsCapturePercentageImple-mentedI-Beams&Pipes7%to14%0%V-Grating21%to36%

SplitGrating16%to29%5%

ContinuousGrating4%to29%Bend3%to31%3%

• Washdowntransportthetransportofdebrisbycontainmentsprayandbreak"owwheredebrismaybecapturedbyonlygratings.Toreiterate, washdownhasthepotentialtoreducetheamountofdebrisavailablefor transporttothestrainersbecausedebrismaybeheld-uporcapturedby gratings.ThisphenomenonisreferredtoascaptureinthisRAI.Thefol-lowingisalistofconservativisms,assumptions,andmethodologiesused inthedeterminationofthewashdowntransportfractions:

-Washdowntransportfractionsaredeterminedforuppercontainmentandbreaklocationswheredebrisremainsinthecompartmentand aresubjectedtothecontainmentsprays;i.e.,thesteamgenerator compartment.

-LDFG"nesarenotcapturedbygratings.Therefore,100%of"nestransporttothecontainmentpool.

-Fornon-"nedebris,<1%to48%ofdebrispassesthroughthegratingperTable4-3oftheDDTS.Thetransportcalculationimplementeda gratingpassthroughof50%forthe"rstgratingandagratingcapture of0%foreachadditionallevelofgrating.

-Thesprayswerealsoassumedtoalwaysbeinitiatedforwashdown analysis.*Pool"lltransportthetransportofdebrisbysheeting"owcausedbybreakandcontainmentspray"owstotheemergencycorecoolingsystem (ECCS)sumpsorinactivecavities.

-DuetothelocationoftheECCSsumpsandpossiblebreaklocations,pool"lltransportwasdelineatedintobreaksinsideandoutsidethe secondaryshieldwall.

-Determinedfroma"rstordertialrateequation,andonlytransports"nedebristhatislocatedonthe"oorduringinjection.

-Transportsdebristothestrainersandinactivecavities.Tuesday1 stMarch,2016:19:32,Page362of393 DRAFTPART4.RAIRESPONSES(ROUND2)

• Recirculationtransportthetransportofdebrisfromtheactiveportionsoftherecirculationpooltothesumpstrainerswhichwasdeterminedby computational"uiddynamic(CFD)simulations.Thefollowingisalistof conservativisms,assumptions,andmethodologiesusedinthedetermina-tionoftherecirculationtransportfractions:

-CFDmodelswerenotsimulatedforallthebreaklocations.Alargebreakintheprimaryloopwasassumedtoberepresen-tativeforthesteamgeneratorcompartmentbreak,belowsteam generatorcompartmentbreak,andreactorcavitybreak.Although the"owpathsaresomewhattfortheprimaryloopbreak andthereactorcavitybreak,thisapplicationisconservativebe-causetheenergyofareactorcavitybreakwouldlargelydissipate beforereachingthemainpool.Alargebreakinthesafetyinjection(SI)pumpdischargelineofLoopBwasassumedtoberepresentativeforbreaksinthepres-surizercompartment,pressurizersurgeline,RHRcompartment, andannulus.ThisisreasonablesincetheCFDmodelanalyzes aLBLOCAoutsidethesecondaryshieldwall,andthelargest breakthatwouldoccurinthepressurizercompartmentwouldbe aMBLOCA.-TheminimumLBLOCAcontainmentpoolheightwasmodelled.Thisisconservativebecausetheminimumwaterheightproduceslarger bulkvelocitiesthanacontainmentpoolwithalargerheight(ii.).

-Thetotal"owratesin(viathecontainmentsprayandbreak"ow)andout(viathestrainers)ofthemodelwasthemaximum,twotrain operation"owrateof14,040gpm.

• Erosiontransportthegenerationandtransportof"ber"neserodedfromsmallandlargepiecesofLDFGhelduponstructuresinthepooland uppercontainmentwasassessedusingdatafromtheDDTSstudyand30-daygenericerosiontesting(iv.).Thefollowingisalistofconservativisms, assumptions,andmethodologiesusedinthedeterminationoftheerosion transportfractions:

-Asprayerosionfractionof1%for"ne"bergenerationandtransportwasappliedforallsmallandlargeLDFGdebrishelduponstructures abovethepoolelevation.Thiserosionfractionwasappliedforall breaksizesindependentofwhethersprayswouldrealisticallybeon orforaspeci"cscenario.

-Apoolerosionfractionof7%for"ne"bergenerationandtransportwasappliedtoallsmallandlargeLDFGhelduponstructuresintherecirculationpool.The7%erosionfractionrepresentstheupper boundofthe95%con"denceofthemeanerosionvalue(i.)from generic30-dayerosiontesting(v.).Tuesday1 stMarch,2016:19:32,Page363of393 DRAFTPART4.RAIRESPONSES(ROUND2)

• Themethodologydescribedaboveproducestransportfractionsthatarerealisticandconservative.

References:

ii.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCalcu-lation.Revision3.6/10/2014.

iii.ALION-CAL-STPEGS-2916-005,ContainmentRecirculationSumpEvalu-ation:CFDTransportAnalysis.Revision3,October21,2008.

iv.ALION-SUM-WEST-2916-01,CADModelSummary:SouthTexasReactor BuildingCADModelforUseinGSI-191Analyses.Revision4,May22,2014.

v.ALION-REP-ALION-1006-04,ErosionTestingofSmallPiecesofLowDen-sityFiberglassDebrisTestReport,Revision1,November7,2011.4.6.3Question45STPResponse:(Item45,Page104)Thefollowupinquiry,Round1RAI,SSIB6a,impliesthatinLAREncl.4-3,duringblowdown,aportionofsmallandlargedebriswasestimatedtobe captured(orheldup)ongrating,includingpartialareagrating,andhencenot susceptibletotransporttothesumpstrainer.Thisisnotthecase.Figuresof"brousdebriscollectedongratingsduringthedrywellintegratedtestsareshownbelow(Figure1)fromNUREG/CR-6369,Vol.2Pgs.3-29, Figure3-22and3-23[1.].Thesetestswereperformedwithstructuralelements assembledtotheprototypicalcongestionlevel.Itisqualitativelysuggestedby the"guresbelowthattheamountofcongestionassociatedwithhomogenous "beraccumulationwouldnotbelargeenoughtogreatly"owresistance throughthegratings.Furthermore,thestudy(NUREG/CR-6369,Vol.2,Pg.

iii.)concludedthatcaptureofallstructureswasfoundtobeaweak functionof"owvelocityandlocal"owpatterns[1.].Figure1:FibrousdebriscollectedongratingsduringthedrywellintegratedetestsfromNUREG/CR-6369,Vol.2,Pgs.3-29Tuesday1 stMarch,2016:19:32,Page364of393 DRAFTPART4.RAIRESPONSES(ROUND2)Toclarify,blowdownanalysisdoneinsupportLAREncl.4-3doesnotusecapturemetricsfromgratingstoreducetheamountofdebrisavailabletotrans-port.Forexample,noamountofdebriscapturedbygratingsisassumedtobe stuck(held-up)andnotavailableforothertransportmechanisms.IntheblowdowntransportphaseinLAREncl.4-3,theonlyuseofgratingcaptureistoestimatetheratioofdebristhatwouldtransporttoupper containmentversusremainingintheSGcompartmentortransportingtolower containment.Noneofthedebrisisassumedtobecaptured(andhencenot susceptibletotransport)eitheronfullareagrating,partialareagratingorother hold-upmechanismsintheblowdownphasecalculation.Instead,afterblowdown phase,allgenerateddebrisisavailableforremainingtransportmodes.Thisis illustratedinthetransportlogicdiagramsinLAREncl.4-3,Ref.[23],wherethe totalgeneratedquantityofdebrisisdistributedbetweenlevelsofcontainment andsubjecttosubsequenttransportmodes.Anexcerptexample,Figure5.12.2-Smallpiece"berglassdebristransportlogictree(SGcompartmentbreak),from LAREncl.4-3,Ref[23],isshownbelow.Tuesday1 stMarch,2016:19:32,Page365of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure2:LAREncl.4-3Figure5.12.2Tuesday1 stMarch,2016:19:32,Page366of393 DRAFTPART4.RAIRESPONSES(ROUND2)Duringtheblowdowntransportphase,theuseofabest-estimategratinghold-upfraction,(asopposedtoalower-boundvalue)resultsinminimizingthe quantityofdebristhatisconsideredtotransporttouppercontainment.Thisis conservativeandhasprecedentfromthesevaluationofNEI04-07Volume2 EvaluationforGRSection3.6.3,Pg.58)whichstatesFormostlycom-partmentalizedcontainments,theGRrecommendsnodebrisbetransportedto uppercontainment[3.].STPscontainmentincludesdirectpathwaystoupper containment;henceincorporationofreductionsindebristransportedtoupper containmentisconservativeAllconsiderationofgratingsintheSTPblowdown transportanalysisreducethefractionofdebrisblowntouppercontainment withoutreducingthequantityofdebristhatremainsavailableforsubsequent transportmodes.

REFERENCES:

1.NUREG/CR-6369,Vol.2.DrywellDebrisTransportStudy:ExperimentalWork.September1999.2.NUREG/CR-6369,Vol.1.DrywellDebrisTransportStudy.September 1999.3.NEI04-07,Vol.2.PRESSURIZEDWATERREACTORSUMPPER-FORMANCEEVALUATIONMETHODOLOGY.Revision0.December20044.6.4Question46STPResponse:(Item46,Page104)IntheRoverDmethodology,itisslightlymoreconservativetoassumethatsmalldebrisiscapturedonstructuresandcalculatedtoerode,therebyadding tothe"ne"bertransportedtothesumppool.Thefollowingresponsesupports theoriginalSTPmethodologyfordebristransport.Basedonthediscussionthatfollows,thereisnobasisforassumingthatwashdownof"brousdebristhroughgratingswouldincreaseabovethatfound duringtheDDTSifthewashdowntimeissigni"cantlyincreased.Section4.4.1,Con"rmatoryTests,oftheDDTS(Volume2,Pg.4-5)includesthefollowingconclusions:#2.MostoftheSmalldebrispieceswillbewasheddownbywaterwithin"rst10-15minutesafterwhichwashdownreachesanasymptote.#3.Largepieceswillnotbeforcedthroughthegratingevenathigh"ows.Theywillremainonthegratingandmayerodewithtime.Erosionalsoexhibits anasymptoticbehavior.TheSmalldebriscategoryintheDDTS(Volume2,4-3)isdescribedasalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25

Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.Typicallythesepieceswereabout1.5"insizeandpossessedlittleoftheoriginalstructureor thechemicalbinding.

...TheMediumcategoryintheDDTSisdescribedasInsulationdebrispre-tornfromtheblanketbyanair-jetimpingement.These pieceskeepsomeoftheoriginalstructuresintheinnerregions,whiletheylook torn-downorlooseontheoutside.Typicallythesepiecesareabout6"x4"in dimension.Tuesday1 stMarch,2016:19:32,Page367of393 DRAFTPART4.RAIRESPONSES(ROUND2)Thesizedistributionusedinthecurrentanalysesarebasedon(proprietary)ALION-REP-ALION-2806-01,Rev:3.Thesizedistributioncategoriesare:Fines (IndividualFibers),SmallPieces(<6"onaSide),LargePieces(>6"onaside)andIntact(covered).TheSmalldebriscategoryintheDDTScorrespondstotheFinescategoryinSTPcalculationsonthebasisthattheclumpsarecollectionsofindividual "berswithlittleoftheoriginalstructure.TheMediumcategoryintheDDTScorrespondstotheSmallPiecescat-egoryinSTPcalculations.Debrisinthiscategoryisgenerallylargerthanthe gratingvoidsizesandhenceisnotexpectedtobebewasheddownbywater within"rst10-15minutesasdescribedinDDTSSection4.4.1,Con"rmatory Tests,conclusion#2,above,aswasthecaseforSmallDDTSdebris.STPSmallPiecesdebrisbehaviorcorrespondstoDDTSSection4.4.1,Con-"rmatoryTests,conclusion#3,

...willnotbeforcedthroughthegratingevenathigh"ows

...ItisnotedthatthisDDTSconclusiondoesnothaveanylimitationswithrespecttotime.DDTS4.5,SummaryandConclusions,itemsstates:2.Asigni"cantfractionofthemediumpieces(generatedbyjetimpactoninsulationblanket)wouldbe erodedandtransportedtothedrywellpool.Atransportfactorof1.0isrecom-mendedinthecaseofbreakover"ow(e.g.,followingarecirculationlinebreak);

ontheotherhand,forspraysatransportfactorof0.5appearsreasonable.The DDTSrecommendationforthesprays-relatedtransportfactor,0.5,whichwas usedasthebasisforthewashdowntransportfractioninSTPdebristransport washdowncalculations,doesnotincludeany"owduration-relatedrestrictionor

cautions.TheveryfactthatDDTSwashdownanderosiondiscussionisfocusedpri-marilyonerosionindicatesthatwash-throughfordebrisoftsize,i.e.,

greaterthanthevoidspaceofgrating,isnotexpectedtobeanissuewithin anextendedpost-LOCAtimeframe.Onthecontrary,eventhetimeframeof erosion,whichcanonlyhappenifdebrisremainsretainedongrating,issaidto beasymptoticafterashortperiodofexposureto"ow.Onthebasisofthediscussionabove,thereisnobasisforassumingthatwashdownof"brousdebristhroughgratingswouldincreaseabovethatfound duringtheDDTSifthewashdowntimeissigni"cantlyincreased.4.6.5Question47STPResponse:(Item47,Page104)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.6Question48STPResponse:(Item48,Page105)Tuesday1 stMarch,2016:19:32,Page368of393 DRAFTPART4.RAIRESPONSES(ROUND2)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.7Question49STPResponse:(Item49,Page105)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.However,the correctvalueofCSHLforuseincalculationsis1.952ft.4.6.8Question50STPResponse:(Item50,Page105)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.9Question51STPResponse:(Item51,Page106)Vortex,AirIngestion,andVoidFractionTheDecember2008submittalinresponsetoGL2004-02discussedthepoten-tialforvortexing,airingestion,andvoidformationfortheSTPsumpstrainers madebyPCI.STPstrainerprototypetestingatAldenResearchLaboratory veri"edthattheminimum1/2in.submergencewouldprecludeairingestionor vortexdevelopment.SubsequentdiscussionwasheldwiththeNRCsduring theSeptember13,2010publicmeetingconferencecallconcerningRAIs.The NRCnotedthatvortexingisnotlikelytobeanissueforPCImadestrain-ersbasedontestingbySTPandothersthatshowvortexeswillnotoccurfor conditionsboundingtheSTPconditions.Duetolackofanairentrainmentmech-anism(i.e.vortexformation)alongwithcompletesubmergenceofthestrainer, airingestionisnotexpectedtooccur.AlsodiscussedintheDecember2008 submittalwasanevaluationofvoidfractionthatconcludedthat"ashingand subsequentvoidfractionformationwouldnotoccuracrossthestrainer.Thevortex,airingestion,andvoidfractionanalysisconcludedthatvoidfrac-tionoccurringatthestrainerdebrisbedduetoheadlossandtheaccompanying post-LOCAconditionswouldbereversedandanyvoidswouldhavecollapsed beforethestrainerdischarge"uidleftthecontainmentsumpandenteredtheTuesday1 stMarch,2016:19:32,Page369of393 DRAFTPART4.RAIRESPONSES(ROUND2)ECCS/CSSinletpipe.Thenetvoidfraction(i.e.,netairproduction)isthere-fore0%.Therefore,voidfractionisnotanissueforanyofthepost-LOCA"uid associatedpressureandtemperaturecombinationsassociatedwiththesubject "uid"owfromthestrainertotheECCS/CSSinletpipe.TrappedAirinPlenumBoxThestrainercon"gurationissuchthatsumpwatergoesintothestrainermoduleandthengoestothecoretubewhereitisdirectedtotheplenumbox.

Therearefourinletstotheplenumbox(oneforeachconnectedstringofstrainer modules).Theplenumboxcollectsthedischarge"owfromthestrainermodules anddirectsthe"owdownwardtothesumppitwhichcontainstheinletofthe suctionpipetotheECCSandCSSpumps.Vortexbreakersareinstalledinthe sumppitaroundtheinlettothesuctionpipe.Upon"oodingofthestrainermodulesandthesumppitduringtheinitialpost-LOCApool"ll-upphase,someairmaybetrappedunderthecoverofthe plenumbox.Thisairdoesnotconstituteablockageofwater"owfromthe strainerstothesumppit.Anytrappedairintheplenumboxdoesnotincrease thecleanstrainerheadlossorinterferewithwater"ow.Thetrappedairwill slowlydissipateduringoperationoftheECCSandCSSpumps.

NoteTheresponsetothe1stRoundRAIreferredtoadocumentconcerninggasvoidsinthepipingbetweenthesumpstrainersandthesafetyinjectionpumps andcontainmentspraypumps.Thisdocument(Reference58)waspreparedby MPRforSTPinresponsetoGL2008-01ManagingGasAccumulation.Itis acalculationthatdeterminesthemaximumacceptablegasvoidvolumesfor particularlocationsinECCSandRHRpipingbasedonindustryacceptance criteriaforthegasvolumesallowedtotransporttothesystempumps.Sinceit isnotconcernedwithsumpstrainerperformanceandisgermaneonlyforgas accumulationmanagement,itshouldnotbepartoftheresponsetothisRAI.4.6.10Question52STPResponse:(Item52,Page106)ThewaterlevelcalculationforRoverDusesthedeterministicevaluationofwaterlevelthatwasdescribedintheDecember2008submittalfortheGL2004-02response(ML083520326).Thiswasthebasisforthetestingthatshowed acceptablesubmergence.SeeresponsetoRAI31thatexplainsvortexing,deaer-ation,and"ashingwillnotoccurisbasedontestingandconservativeassump-tionsinthelevelcalculation.Thetransportevaluationisalsodescribedinthe December2008submittalandisconsistentwiththesumplevelevaluation.4.6.11Question53STPResponse:(Item53,Page106)Theminimumandmaximumvaluesusedfortwotrainoperationwere1932and2350gpmrespectively(Volume3,Section2.2.8).Theminimum"owrate (1932gpm)usedfortwoandthreetrainsoperablescenarioswastakenfrom STPsDESIGNBASISDOCUMENTCONTAINMENTSPRAYSYSTEM (Volume3Ref.42,Pg.A-40).This"owrateistheminimumprobable"owrateTuesday1 stMarch,2016:19:32,Page370of393 DRAFTPART4.RAIRESPONSES(ROUND2)pertraincalculatedusingFLOMAP(Volume3Ref.42,Pg.A-40).Thismini-mum"owratewascalculatedwiththefollowingsimpli"cationsandassumptions.

• Pipingand"ttingresistancesbasedoofplantcon"gurationandCrane410methodology

• 5percentdegradedpumpcurve

• Maximumcontainmentdesignpressure

• MinimumTechSpecRWSTlevelThemaximum"owratepertrain(2350gpm)usedfortwoandthreetrainsoperablescenarioswastakenastheFLOMAPcalculatedaverageofdesign"ows fortrainsAandBoperationduringrecirculation(Volume3Ref.42,Pg.A-39).TheminimumandmaximumuserenteredvaluesforonetrainCSoperationwere2080and2600gpmrespectively.Themaximum(2600gpm)"owratefor onetrainoperationwasspeci"edinVolume3Ref.41,Pg.16.Theminimum value,foronetrainoperation,wastakenas80%ofthemaximumvalue(Volume 3Ref.41,Pg.16);wherethe80%scalingwastakenastheratioofminimumto maximum"owratefromthetwotrain"owcase.SamplingCS"owratesforeachscenariosrespectiveoperabletrainstateisappropriatebecausenopreferencewasadded(randomandequallyprobable) betweentheminimumandmaximum"owratevalues,andbecauseminimumval-ueswereselectedorscaledtorepresentprobableoutcomes.Selectionofrandom "owratesbetweenminimumandmaximumlimitsisacommonapproachforrig-orousuncertaintypropagationincaseswherephysicalvariabilityorcompeting mechanismsprecludede"nitiveselectionofconservativeparametervalues.Con-tainmentsprayrateissampledinthiscasebecause(1)therearenoinitiating-eventspeci"c(breaksizedependent)"owratesavailablefortheCSpumps;(2)

CS"owsaremostdependentoninitiating-eventindependentparameterssuch astheRWSTlevel,initialpumpsavailable,andvarianceinpumpperformance thatCS"owwithintheappliedranges;and(3)"beraccumulationrate inthefuelisbythe"owsplitdivertedtosprays,soallprobableranges ofCS"owrateshouldbeexercisedtodeterminethequantitativeimpactonall failuremodes.4.6.12Question54STPResponse:(Item54,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.Flashingwas addressedinSTPNOCsDecember11,2008,letter(ML083520326).Tuesday1 stMarch,2016:19:32,Page371of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.6.13Question55STPResponse:(Item55,Page107)StrainerbackwashfromtheRWSTisinitiatedfromSACRG-2(SevereAcci-dentControlRoomGuidelineAftertheTSCisFunctional),Addendum2(which directsenteringSAG-3)aftertheTSCisactivatedbydirectionthroughtheTSC Diagnostic"owchartwhentheCETsindicategreaterthanF.Furtherguid-anceisgiveninStep5.b.4ofSAG-3(InjectintotheRCS)foroperationwith RWSTinbackwashalignment.4.6.14Question55aSTPResponse:(Item55a,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforchemical orheadloss.Headloss,includingchemicalisaccountedforintheplant-speci"cdeterministictesting.4.6.15Question56STPResponse:(Item56,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.16Question57(a)STPResponse:(Item57a,Page108)RoverDdoesnotusethe"ltrationmodelusedinCASAGrande.RoverDusesitsown"ltrationmodelthatassumesno"beronthesumpscreenatthe startofrecirculation.InRoverD,STPdirectlyappliesmeasuredtestdatain-cludingtheuncertaintybounds(obtainedfrommeasurements)toaccountfor bypassuncertainty.Thedataare"ttotheupper,central,andlowerboundof measurementuncertainty.Assumingno"beronthestrainerwhenrecirculation beginsshouldmaximizetheamountof"berpenetrationtothecore.4.6.17Question57(b)STPResponse:(Item57b,Page108)RoverDdoesnotusethe"ltrationmodelusedinCASAGrande.RoverDusesitsown"ltrationmodelthatassumesno"beronthesumpscreenatthe startofrecirculation.4.6.18Question57(c)STPResponse:(Item57c,Page108)Tuesday1 stMarch,2016:19:32,Page372of393 DRAFTPART4.RAIRESPONSES(ROUND2)InRoverD,STPdirectlyappliesmeasuredtestdataincludingtheuncertaintybounds(obtainedfrommeasurements)toaccountforbypassuncertainty.The dataare"ttotheupper,central,andlowerboundofmeasurementuncertainty.

tconditions(forexample"owratesandconcentrations)areincluded inthemeasuredtestdataandappropriatelyaccountedforintheuncertainty boundsofthe"ttothedata.Thetestdata"tforthetboundsisshowninthe"gure.STPPCIStrainerdatashownwith"ltration"tsfromtestmeasurementsatdtlevelsof"beraccumulationshownas"tstolowerboundofdata,central"tofdata,and upperbound"tofdata.4.6.19Question57(d)STPResponse:(Item57d,Page108)Anactualstrainermodulewasusedtoperformtestinginordertoeliminateconcernsrelatedtothecomplexdesignofthestrainersurface.tapproach velocitieswereusedaswellasdtconcentrations.Testmeasurementsfrom sixtestswereusedto"tthedataboundsofthedata.Asdescribed,otherresponses,theuncertaintyboundsofthetestmeasure-mentsaredirectlyevaluatedintheRoverDapproachasshowninAttachment

7.4.6.20Question57(e)STPResponse:(Item57e,Page109)TheRoverDstrainerbypasscalculationusesimplicit(Adamsmethod)in-tegrationofthemassconservationequations.Themethodiswell-knownasa robustsolverfornordinarytialequationsandisnotsubjectto timestepsizeissuesassociatedwithexplicitmethods.Themethodandequations areclearlydevelopedandexplainedinAttachment7.Tuesday1 stMarch,2016:19:32,Page373of393 DRAFTPART4.RAIRESPONSES(ROUND2)STPPCIStrainer"ltrationfractionsfromtestmeasurementsatdtlevelsof"beraccumulationshownas"tstolowerboundofdata,central"tofdata,andupperbound "tofdata.4.6.21Question57(f)STPResponse:(Item57f,Page109)TheRoverDstrainerbypasscalculationusesthemeasuredtestdatadirectlyintheequationsshowninAttachment7.Theparametersusedareshownin Attachment7alongwiththeinputsusedinuncertaintyboundcalculations.4.6.22Question58STPResponse:(Item58,Page109)Theapparentdiscontinuityresultsfrompipesbeingofdiscretesizesandthattherearevaryingnumbersofthedtsizepipes.Seethetablebelow.Thereare15discretepipesizesatSTP,andatotalof628weldlocationswhereabreakcanoccur.Ofthese15discretepipesizes,breaks13inchesand largercanonlyoccuron3ofthem(20%).Ofthe628weldlocations,breaks 13inchesandlargercanonlyoccuron64ofthem(10.2%).Inaddition,CASA Grandeissetuptosamplelargerbreaksatagivenlocationmorefrequently thansmallerbreaks,sowewouldexpecttoseerelativelyfewbreaksbetween13 and20inchesontheselargerpipes.Inconclusion,thebreaksizesgoingtofailurearerepresentativeofthepipesizesattheSTPpowerplantandthelikelihoodofbreaksonthosepipes.The indicatedthatthebehaviormaybenon-physical,wheninfact,thisbehavior isafunctionofthe15discretebreaksizesatSTPandthefactthatsmallerbreaks arelesslikelytofailthanlargerbreaksTuesday1 stMarch,2016:19:32,Page374of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:PipeSizesatSTPandtheNumberofWeldsAssociatedwithEachPipeSizeSTPPipeSizesSTP#ofWelds0.614320.8153 1.3389 1.68985 2.1256 2.62626 3.43890 5.189886.81354 8.50030 10.126131 12.81410 27.50016 29.00020 31.00028 6284.6.23Question59STPResponse:(Item59,Page109)Forclaritythisresponsehasbeenbrokenupintothreemajorsections:1)ImportofCADGeometryintoCASAGrande,2)ValidationofCASAGrande DebrisGeneration,and3)Conclusions.ImportofCADGeometryintoCASAGrande:

Therearefourtypesofgeometry(PipeExtractInsulationData,EquipmentInsulationdata,ConcreteandSteelStereolithography"les)thatcanbeimported intoaCASAGrandesimulation.Thesefourtypesofgeometryanddescriptions ofhowtheyareimportedandusedintheCASAGrandesuitearedescribed below.PipeExtractInsulationData:PipeExtractdataisextractedfromthepip-ingassemblyinthe3DcontainmentCADmodelbyaproprietaryAutoDesk Inventoradd-in(createdbyAutoDeskforAlion)andincludesallinformation aboutpipingandpipinginsulationneededtorebuildthepipinginsulationgeom-etrynumericallyinsideofCASAGrande.Speci"callyPipeExtractdataincludes pipesegmentlengths,pipenames,pipeinsulationtypes,Cartesiancoordinates ofextractedpointsonpipes(Work-Point),bendradiiofextractedWork-Points, innerandouterdiametersofpipes,andWork-Pointtypes(ie.valve,hangar, weld,etcÉ).AnexampleofapipesegmentinaPipeExtractinput"leisshown belowinFigure1.ThedatafromeachpipesegmentinthePipeExtract"leisreadintoCASAGrandeandusedtocreateanumericalreconstructionofthepipinginsulation volumeswithpointvolumescalledvoxels.Theusercanspecifythenumerical resolutionofthepipinginsulationreconstruction(withvoxels)intheCASATuesday1 stMarch,2016:19:32,Page375of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure1:PipeExtractFileDataExample.Grandesimulationbyde"ninglinearresolutionandnumberofazimuthalbinsintheinputdeckFigure2.Figure2:ResolutionInputsforCASAGrandePipingReconstructionAnexamplereproductionofPipeExtractdatausingtheaboveuserde"nedlinearresolutionandnumberofazimuthalbins(Figure2)isshownbelowin Figure3.Noticethatthereare12bandsthatrunthelengthofthepipecurve whichshowtheazimuthaldiscretizationofthevoxelsintobins.Eachpointonthe bandsisinoneazimuthalbinandapproximatelysixinches(LinearResolution) awayfromotherpointsonthesameband(with"exibilityinlineardiscretization toaccountforcurvature).SpotchecksaredoneonsegmentsofpipinginsulationwitheachnewsetofTuesday1 stMarch,2016:19:32,Page376of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure3:CASAGrandeRepresentationofCurvedPipeSegmentPipeExtractdatathatisloadedintoCASAGrandeusingtheCADsoftwaresgeometryasthebaselineforcomparison.TheInventor2013representationof theinsulationsegmentisshownbelowinFigure4Figure4:Inventor2013CADRepresentationofExampleSegmentWhenthevolumeoftheCASAGrande(3.2300E4in 3)andInventor2013CADrepresentation(3.0954E4in 3)oftheinsulationsegmentwerecomparedthepercentdbetweenthevolumesforthisexamplewasfoundtobe4.25%.1.EquipmentInsulationTextFiles:TheequipmentinsulationimportformathasbeenupdatedsinceV1.6ofCASAGrandetothemoreaccurateinput formatintroducedinV1.7.Thisequipmentinsulationformatrequiresthe usertosupplyatext"leforeachpieceofequipment;wherethedataof theequipmentinsulationtext"lecontainsx,y,zlocations(inches),point volume(V)value(in3)andinsulationtypeforeachofthevoxelsthatdis-cretizeequipmentinsulation.AnexampleofinputfromanSTPequipment insulationtext"leisgivenbelowinFigure5;wherethedataineachrow isformattedtoreadx,y,z,V,andInsulationTyperespectively.BecauseofthesimplicityoftheEquipmentinsulationformatthese"lescanTuesday1 stMarch,2016:19:32,Page377of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure5:Exampletextfromequipmentinsulationinput"lebecreatedinanExcelspreadsheet.ForSTPhoweverthese"leswerecreatedfromSTLexports(forhighresolution)ofequipmentfromtheCADsoftware.

TheseSTL"leswerethenpre-processedtosupplytheCartesiandatasumma-rizedinFigure5.Notethatitisalsopossibletoimportpipinginsulationorany otherinsulationintothemodelusingthisinputmethod.1.ConcreteStereolithography(STL)"le:Theconcreteinput"leisabinarySTLdata"lecontainingallCADgeometryoftheplantconcretestruc-tures.TheconcreteSTL"leisusedtorepresentrobustbarriers(insulation shielding),andforconcretecoatingsdestruction.TheconcreteSTL"leis interpretedasacollectionofsurfacetrianglefaces(facets)andrespec-tiveunitsurfacenormalsinthreespace.Forconcretecoatingscalculations thesetrianglesarere"nedtoauserspeci"edsurfaceareatoensurethat coatingsquantitiesarecalculatedaccurately.Asanexample,apictureoftheCASAGrandereconstructionoftheSTPconcreteSTLdataisshownbelowinFigure6.Notethatthisimageisthedirectimportusedasde-structionbarriersanddoesnotrepresentre"nementsmadeforquali"ed coatingsdestruction.Whentheconcrete"leisimportedintoCASAGrandethe"leisvisuallyinspectedforerrors.Firstthemodelischeckedtomakesurethattriangles arentvisuallyoverlapping.NotethatthereisanumericalSTLchecker inCASAGrande,butthevisualinspectionisforaddedprotectionagainst STLdatainterpretationerrors.Nextthetrianglenormalvectorsarevi-suallyinspectedtomakesurethattheyarepointingoutofthesurface.

ThesechecksinsurethattheCASAGrandeinterpretationoftheconcrete "lewillcorrectlysimulatebarriersbetweenbreaksandinsulationtargets.2.SteelSTL"le:Thesteelinput"leisabinarySTLdata"lecontainingallTuesday1 stMarch,2016:19:32,Page378of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure6:CASAGrandereconstructionofconcreteSTLinput"leCADrepresentationsofplantsteelstructures.ThesteelSTL"leisonlyforsteelcoatingsdestructioncalculations;steelstructuresarenotusedfor insulationshielding.ThesteelSTL"leisimportedinCASAGrandein thesameformatastheconcreteSTL"le.Forcoatingscalculationsthese trianglesarere"nedtoauserspeci"edsurfaceareatoensurethatsteel coatingsquantitiesarecalculatedaccurately.Formostplantsanalyzedthe userspeci"edtrianglere"nementsurfaceareaissetto16in2whichgives goodre"nementoverthebreakspectrum.Anycoarserre"nementarea speci"edwilldecreasesimulationruntimebutwillbelessaccurate.ValidationofCASAGrandeDebrisGenerationTheSTPCASAGrandeinputgeometryhasbeenveri"edforimportaccu-racy,andcalculateddebrisgenerationinCASAGrandehasbeenbench-marked againstCADcalculatedvalues.ImportaccuracychecksinCASAGrandehave beenautomated.AlineisavailabletoassigntheCADcalculatedtotalvolume ofeachimportedinsulationtypeintheinputdeck(DebrisVolumefromCAD ModelinputinFigure7Below).WhenrunningCASAGrandetheuserenteredDebrisVolumefromCADModelinputvalue,iscomparedtoitscorrespondingimportedinsulationtype.

Thiscomparisonisautomaticallywrittentoa"leintheoutputsofthesimu-lationintheCASAvsCADInsulVol.txttext"le,andcanbedirectlyprocessed asacommondelimited"leinExceltogiveacomparisontable.STPsimport comparisontableisshownbelowinTable1.ExaminingtheCASAGrandeautomatedimportcomparisonfortheSTPgeometry,itcanbeseenthatallinsulationtypevolumeshavebeenconserved within2%.Tuesday1 stMarch,2016:19:32,Page379of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure7:DebrisVolumefromCADModelinputTable2:STPCASAGrandeVs.CADinsulationvolumesimportcomparisonDebrisTypeCADInsulationVolume(ft 3)CASAGrandeIn-sulationVolume (ftft 3)Ratio(CASA/-

CAD)Low-Density Fiberglass (LDFG)9893.4989729.78670.98345Microtherm24.89324.89220.99997Insulationdebrisgenerationhasbeenbench-markedforvalidationusingaDEGBbreakatSTPweld31-RC-1402-NSS-RSG-1D-ON-SE.TheCADmodel InsulationdebrisgenerationvalueswerecalculatedbyaCADanalystusing BooleanoperationsavailableintheAutoDeskInventor2013software.Asideby sidecomparisonofpicturesfromthedebrisgenerationcalculations(forNukon) performedinCASAGrandeandbytheCADanalystisshownbelowforqual-itativeinspectioninFigure8.Noticethatinbothpictures(Figure8leftand right)interferenceoftheZOIwithpipingishighlightedinred.Tuesday1 stMarch,2016:19:32,Page380of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure8:CASAGrande(left)VsCAD(right)debrisgenerationpicturesResultsforCASAGrandeVs.CADcalculatedSTPinsulationdestructionoverallinsulationdebristypesforaDEGBbreakonweld31-RC-1402-NSS-RSG-1D-ON-SEaregivenbelowinTable2.Table3: default InsulationTypeZOISizeCADDebrisVolume(ft 3)CASAGrandeDebrisVolume (ft 3)PercentD enceMicrotherm28.6D0.0131.7197.07.0D317.2326.32.811.9D553.6578.44.4Nukon17.0D810.2829.72.47.0D295.0283.44.0ThermalWrap11.9D623.3606.62.717.0D1,134.81,138.70.3AllSTPinsulationdestructionamountscalculatedinCASAGrandearewith5%ofthevaluescalculatedinCADexceptforMicrotherm.AlthoughtheMi-crothermdebrisgenerationvaluescomparedbetweenCADandCASAGrande calculationsshowalargepercentdthemagnitudeofthedestroyed Microthermquantitiescalculatedareverysmallincomparisontothosecalcu-latedforNukonandThermalWrap.Notethatcalculationsthatresultinsmaller amountsofcalculateddebrisaresubjecttohigheruncertaintyinsideoftheCAD model(SeepercentdforMicrotherminTable2);wheremanyofthese debrisarelocatedinsmallpenetrationsandrequireaconsiderationfromthe CADanalystwhethertheyshouldbeincludedornot.AsimilarvalidationhasbeenperformedforcoatingsquantitiesusingtheSTPmodel.ThisvalidationuseduntypicalZOIsizesbutgivesacomparison betweenCADandCASAGrandecalculatedquali"edcoatingsvalues.Results ofthecomparisonaregivenbelowinTable3.InTable3thereisgoodagreementbetweentheCASAGrandecalculatedTuesday1 stMarch,2016:19:32,Page381of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table3:CASAGrandeVs.CADcalculatedquali"edcoatingsdebrisgenerationquali"edcoatingsdebrisquantitiesforconcreteandsteelat31-RC-1402-NSS-RSG-1D-ON-SE.Notethatcalculationsthatresultinsmalleramountsofcal-culatedquali"edcoatingsdebrisaresubjecttohigheruncertaintyinsideofthe CADmodel(similartoinsulation);wheremanyofthesedebrisarelocatedin locationsthatrequireaspecialconsiderationforinclusionbytheCADanalyst.

Alsonotethatcalculatedquali"edcoatingsdebrisquantitiescanbere"nedby changingtheareadiscretizationparameterintheinputdeckforType2debris.ValidationofCASAGrandedebrisgenerationroutineshavealsobeensuc-cessfullyperformedforotherplantsgeometries,buthavenotbeenincludedin thisresponsebecauseconsenthasnotbeenrequestedfortheiruse.

Conclusions ValidationoftheimportofSTPsinsulationgeometryintoCASAGrandehasbeenperformedbycomparisontototalvolumesintheAppendixBdevel-opedSTPCADmodelforeachinsulationdebristype.Thisimportcomparison forinsulationvolumeconservationisautomatedintheCASAGrandesuiteand isperformedatthebeginningofeachnewsimulation.CASAGrandedebris generationroutinesforbothinsulationandquali"edcoatingsdestructionhave beenbench-markedtoCADcalculatedvalueswhichhaveshownaccurateresults fortheSTPgeometryandotherplantcomparisonsnotreleasedinthisdocu-ment.LargeinCASAGrandevs.CADcalculateddebrisquantities areapparentforsmallmagnitudedebrisgeneration.Thesemaybe theartifactoftheCADanalysthavingtoperformlineofsightdebris generationcalculationsinsideofaCADmodel.Lineofsightcalculationsfor debrisgenerationareautomatedintheCASAGrandesuiteandareaccurateup totheresolutionoftheimportedgeometry.4.6.24Question60STPResponse:(Item60,Page110)RoverDdoesnotusecumulativedistributionfunctionstodeterminetheriskordeterministicfailurecriteria.CASAGrandeisusedinanon-probabilistic way,only"ndingtheamountof"ne"berdebristhatiscreatedandtransported tothesumpwithoutuncertaintydistributions.Theamountof"ne"berdebris transportedincludeslatent"bersanderoded"ber.Tuesday1 stMarch,2016:19:32,Page382of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.6.25Question61STPResponse:(Item61,Page110)Thezoneofin"uence(ZOI)isthevolumeaboutthebreakinwhich"uidescapingfromthebreakhastenergyto generatedebrisfrominsulation,coatings,andothermaterialswithinthezone (1).TheZOIradiusisdependentonthedestructionpressureofagivendebris sourceandisproportionaltotheinternal"uidconditionsandambientconditions ofcontainmentintermsofpressureandtemperature.Inbothsphericaland hemisphericalZOIcalculations,jetre"ectionisaccountedforintheconversion ofanANSIjettoanequivalentsphericalorhemisphericalvolume.TheZOIis representativeofANSIjetpressuresandjetre"ection/impingementpressures foragivenbreakthatwoulddestroyspeci"cdebrissources.TheZOIboundary representsthelowestimpingementpressuretocauseaspeci"cdebrissourceto

fail.HemisphericalZOIsareutilizedintheCASAGrandeevaluationasanap-proximationforlongitudinalbreaks,typicallyfromafailedweldorvalvethat doesnotresultinfullradialandaxialofseveredpipeendsasinthecase ofaDEGB.NEI04-07statestheZOIforlongitudinalbreakscanbesimulated asahemispherewitharadiusdeterminedbythedestructionpressureofthe insulationthatwouldbebythepostulatedbreak(1).Ifaspeci"cinsu-lationfailswithina17.0DZOIforexample,thiscanbeanalyzedasaDEGBon pipewithinnerdiameterofDinwhichtheZOIisaspherecenteredonthe pipeaxis(thebreakdiameterofaDEGBisequaltotheinnerdiameterDof thepipe).Inaddition,theinsulationdebrisgeneratedbyalongitudinalbreakis analyzedwithinahemisphericalZOIofradius17.0DwhereDisthediameter ofthebreakandthe"atfaceoftheZOIistangenttotheoutersurfaceofthe pipe.Boththesphericalandhemispherical17.0DZOIsrepresentthesamejet pressureswithina17.0Dboundaryalthoughtheirshapeandbreaksizesare t.SphericalZOIDbreakdiameter=innerpipediameterHemisphericalZOIDbreakdiameter

<innerpipediameterSimilartosphericalZOIs,robustbarrierspreventjetexpansionforhemi-sphericalZOIsandreducetheencompassingvolumeofthedestructionzone.

AllZOIsaretruncatedatrobustbarrierinterferenceintheCADmodelwhich providesavisualandanalyticalrepresentationofcon"nementtojetexpansion (highenergyjetscannotexpandthroughsolidstructuresandthereforeZOIvol-umesarereducedattheseinstances).Forexample,Figure3showsthereduction ofaZOIvolumethatextendsbeyondarobustconcretewallintheCADmodel.FromNEI04-07Volume2,theZOIrecommendedintheGR[NEI04-07Volume1]Section3.4isasphericalboundarywiththecenterofthespherelo-catedatthebreaksite.TheuseofasphericalZOIisintendedtoencompassthe ofjetexpansionresultingfromimpingementonstructuresandcompo-nents,truncatingthespherewhereveritintersectsanystructuralboundaryor largerobustequipment.TheGRrecommendsthatZOIsizingbedeterminedus-Tuesday1 stMarch,2016:19:32,Page383of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure3:ExampleofZOItruncationatrobustconcretebarrieringtheAmericanNationalStandardsInstitute/AmericanNuclearSociety(AN-SI/ANS)58.2-1988standardforafreelyexpandingjet(ANSI/ANS58.2-1988).

ThebaselineZOIcomprisestheinsulationtypethatgeneratesthelargestZOI ofallpotentiallyinsulationtypes(2).Debrisvolumesgeneratedfromlongitudinalbreaksaredeterminedbycon-strainingthe"atfaceofthehemisphericalZOIperpendiculartothebreakvector andtangenttotheoutersurfaceofthepipe.InCASAGrande,debrisquanti-tiesarecalculatedfromhemisphericalZOIswithrandomlysampled(foreach simulatedbreak)orientationsaroundthepipesurfaceatbreaklocationswith CADinterferences.ThisisperformedsimilartoguidanceinNE04-07Volume1, whichstates,[for]hemisphericalZOImodeling,thebreakorientationneedsto besimulatedatvariousanglesaroundthelooppipingtodeterminemaximum debrisgeneration(1).TheCASAGranderisk-informedmethoddfrom NEI04-07bysamplingrandombreakorientationovermanybreakscenarios withtrackedvarianceoverthetotalrisksolutiontoensurethatallcontributing combinationshavebeensampled.Thistypeofvariancetrackingensuresthatall distributions,includingbreakorientationandalluserentereddistributionshave beenproperlysampledovertheirfullranges.Ifthebreakinquestionoccurson thebottomofapipenearthe"oor,theboundaryoftheZOIisrepresentative ofalljetre"ectionsthatoccurfromthebreakjetimpingementontheconcrete "oor,asvisualizedinFigure4.

REFERENCES 1.NEI04-07Volume1.PressurizedWaterReactorSumpPerformanceEval-uationMethodology.Revision0:NuclearEnergyInstitute,December2004.2.NEI04-07Volume2.SafetyEvaluationbytheofNuclearReactorRegulationRelatedtoNRCGenericLetter2004-02,Revision0,December6, 2004.Revision0:NuclearEnergyInstitute,December2004.3.ANSI/ANS-58.2-1988.DesignBasisforProtectionofLightWaterNuclearPowerPlantsAgainsttheEofPostulatedPipeRupture.58.2-88:American NuclearSociety,October6,1988.Tuesday1 stMarch,2016:19:32,Page384of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure4:HemisphericalZOIexampleonbottomof31"pipe4.6.26Question62STPResponse:(Item62,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.27Question63STPResponse:(Item63,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Thede-brisdistributionisaccountedforinthebasisfortheplant-speci"cdeterministic

testing.4.6.28Question64STPResponse:(Item64,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.29Question65STPResponse:(Item65,Page111)TheRoverDmethodology(seeAttachment7)doesnotuseCASAGrandeTuesday1 stMarch,2016:19:32,Page385of393 DRAFTPART4.RAIRESPONSES(ROUND2)tocalculateconditionalprobabilitiesordeterminefailures.RoverDmethodologyassumesthatanybreakthatgeneratesmore"brousdebristhanwasrepresented inthetestinggoestofailure(coredamage).Thedeterministictestingiscredited withshowingthattherearenofailuresforconditionsboundedbythetested con"gurationanddebrisloading.Safetymarginisprovidedinthedeterministic sense.Itiscomprisedoftheconservatismoftheengineeringassumptionsand methodologyandtestedcon"guration(e.g.,chemicalfailedcoatings, etc.).TheresponsetotheSTSBRAIinAttachment6providessomeadditional informationonconservatismintheanalysisandtesting.4.6.30Question66STPResponse:(Item66,Page111)TheRoverDanalysisreliesontheUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatvery little"berarrivesonthecore.Theamountsaresosmallthatitisunlikely mixing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.Insummary,STPNOCsevaluationshowsthatthesmallamountsof"berthatmayaccumulatewouldnotcorecoolingorBAP,suchthattheywould notclosingGL2004-02.STPNOCsanalysisissimilarinapproachand conclusionstohowtheNRCaddressedBAPintheSEtoWCAP16793-NP.4.7ML15091A440,STSBResponses4.7.1Question4STPResponse:(Item4,Page113)AsdiscussedinapublicmeetingwiththeNRConFebruary4,2015,STPNOCplanstoproposeachangetotheTSforECCSandforCSStoadda LCOandactionstatementspeci"ctodebrisTheoperabilityrequirement fortheLCOwillbebasedonthequantityofdebrisintheSTPdebrisanalysis andoperabilitydeterminationswillnotinvolveapplicationofprobabilisticrisk.Aspresentedinthemeeting,STPNOCisintheprocessofrevisingitsrisk-informedGSI-191pilotlicensingapplicationtoimplementamuchlesscomplexRiskoverDeterministic(RoverD)methodology.RoverDwillformthetechnicalbasisfortheproposedchangetotheTS.InRoverD,theeofdebristhatareboundedbytheplant-speci"ctestingaredeterministicallymitigatedinaccordancewithNRC-acceptedmethodology forresolutionofGL2004-02.ByapplyingpipebreakfrequenciesfromNUREG 1829,STPNOCshowsthattheriskassociatedwithdebrisfrompipebreaksthat generatequantitiesofdebristhatarenotboundedbyplant-speci"cprototypical testingisverysmall,inaccordancewiththeacceptancecriteriaofRG1.174.The breaklocationsthatcangeneratedebrisoutsidetheassumedtestconditionsare RCSbreaksinthepressurizersurgelineandRCSlooppiping.Defenseindepth andsafetymargininthetestingandcalculationassumptionsprovidereasonable assurancethatthesumpstrainerscanperformtheirsupportfunctionsforECCS andCSSevenforthedebrisgeneratedfromtheselargerbreaks.MoredetailwithTuesday1 stMarch,2016:19:32,Page386of393 DRAFTPART4.RAIRESPONSES(ROUND2)regardtoRoverDisprovidedinAttachment7.TheLCOforthechangetotheTSwillbebasedontheamountofdebrisintheSTPdebrisanalysis.ThedraftLCOpresentedintheFebruary4,2015, meetingread:ReactorContainmentBuildingemergencysumpshallbeOPERA-BLEbylimitingthecontainmentdebrisquantitiestobelessthanor equaltotheSTPdebrisanalysisassumptions.Theoperabilitydeterminationforapotentiallydegradedornonconformingconditionwouldinvolveevaluationofthequantity,natureandtransportability ofthedebrisinquestiontodetermineifitiswithintheSTPdebrisanalysis.It doesnotinvolveariskassessment.Thespeci"citemslistedintheRAIarediscussedbelow.ExceptfortheLOCAfrequencyassumptions,whichwillberemovedasafactorintheop-erabilitydetermination,theyareassumptionsthataretypicalinengineering analysesandwhichoftenhaveconservatismsthatcanbeusedformargininan operabilitydetermination.1.Generalassumptions2.Equipmentfailureassumptions(priortostartofrecirculation):Totheextentthattheseareusedtoestablishthequantityofdebrisassumedin theplant-speci"ctesting,theycouldbeusedtoidentifymargin.3.LOCAfrequencyassumptions:Thiswouldnotbeappliedintheoperabilitydeterminationandwillberemovedfromthelist.4.Debrisgenerationassumptions:Thereareassumptionsinthemodelingforhowmuchdebrisisgeneratedatvariouslocationswhicharerelated tophysicalconditionssuchascreditforpresenceofphysicalbarriersto breakeThesearenotrelatedtotheriskandcouldpossiblybere-visedtoreducetheamountofdebrisassumedtobegeneratedandprovide additionalmargin.5.Chemicalassumptions:Theseassumptionsarenotrelatedtotheriskevaluation.Theplant-speci"ctestingusedWCAP-16530todetermine thedebrisquantitiesforthetest.OtherSTPtestinghasshownthatSTP hasverylittlechemicalWithlessassumedchemicalonhead loss,thestrainerscanhandlemoredebris.Thereissigni"cantmarginthat canbeappliedinanoperabilitydetermination.6.Debristransportassumptions:Theseassumptionswouldgenerallybeap-pliedtodetermineifanidenti"edconditioninvolvesdebristhatistrans-portable.Ifitisnottransportable,thenitgenerallyshouldnotbeof concern.Theremaybesomeconservatismthatcanbeappliedonacase-by-casebasis.ThereisnoPRA/riskelementforthistypeofevaluation.Tuesday1 stMarch,2016:19:32,Page387of393 DRAFTPART4.RAIRESPONSES(ROUND2)7.Headlossassumptions:ThedebrisheadlossusedforNPSHisbasedontestresults.ConservativeassumptionsfortheNPSHdeterminationinclude maximumsumptemperature,minimumsumpwaterlevel,maximumpump "owrates,andconservativecalculationofthecleanstrainerheadloss.8.Degasi"cationassumptions:Vortexing,airingestion,andvoidfractionareaddressedseparatelyasitsownissue.Asshownbytesting,thePCIde-signedstrainersarenotsubjecttovortexingissuesevenwithaverylow submergence.Vortexbreakersareinstalledinthesumppit.Voidfractionis notaconcernbasedonconventionalhydraulicand"uid"owcalculations.9.Penetrationassumptions:Fiberpenetrationisameasuredvalueandmea-surementuncertaintiesareincludedintheevaluation.ThereisnoPRA/risk elementassociatedwiththisparameter.10.Coreblockageassumptions:Theevaluationassumesthecoreandbypass"owisfullyblockedforallsmallbreaksandallhotlegbreaks.Itisassumed

that<15g/FuelAssemblywillprovideadequatecoolingformediumandlargecoldlegbreaks.Thisisaconservativeassumptionthatcouldbe reviewedformargininanoperabilitydetermination.11.Acceptancecriteriaassumptions:Allofthefactorsabovegenerallyfeedintoacceptancecriteria.Tuesday1 stMarch,2016:19:32,Page388of393 DRAFTBibliographyAlionScience&Technology(2008).GSI-191ContainmentRecirculationSumpEvaluation:DebrisGeneration.ALION-CAL-STPEGS2916-002,Revision 3,(Reference5toSTPSTI33647079),AlionScience&Technology,Albu-querque,NM.AlionScience&Technology(2009).InsulationDebrisSizeDistributionforUseinGSI-191Resolution.ALION-REP-ALION2806-01,Revision4, ML15091A440,AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2011).ErosionTestingofSmallPiecesofLowDen-sityFiberglassDebris-TestReport.ALION-REP-ALION1006-04,Revision 1,ML14202A045,AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2014).Risk-InformedGSI-191DebrisTrans-portCalculation.ALION-CAL-STP8511-08,Revision3,(Referencein ML15091A440),AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2015a,April).CASAGrandeTheoryManual.ALION-SPPALION-I009-10,STPSTI34179370,AlionScience&Technol-ogy,Albuquerque,NM.AlionScience&Technology(2015b,July).FinalCASAGrande,RoverDandDEGB,FiberFineandIOZDebrisGenerationQuantitiesandDocumenta-tion.LTRMAS-2K15-07-21R0,STPSTI34164251,AlionScience&Tech-nology,Albuquerque,NM.AREVA(2008,August).SouthTexasProjectTestReportforECCSStrainerTesting.AREVANPDocument66-9088089-000,AREVANP,7207IBM Drive,Charlotte,NC28262.Arrow,K.J.(1951).SocialChoiceandIndividualValues.Wiley,NewYork.Budnitz,R.J.,G.Apostolakis,D.M.Boore,L.S.K.J.Coppersmith,C.A.Cornell,andP.A.Morris(1998).Useoftechnicalexpertpanels:Ap-plicationstoprobabilisticseismichazardanalysis.RiskAnalysis18,463-469.Clement,R.T.andR.L.Winkler(1999).Combiningprobabilitydistributionsfromexpertsinriskanalysis.RiskAnalysis19,187-203.Cooke,R.M.(1991).ExpertsinUncertainty:OpinionandSubjectiveProbabilityinScience.OxfordUniversityPress,NewYork.

389 DRAFT BIBLIOGRAPHYCrenshaw,J.W.(2012,January).SouthTexasProjectUnits1and2DocketNos.STN50-499,SummaryoftheSouthTexasProjectRisk-InformedApproach toResolveGenericSafetyIssue(GSI-191).LetterfromJohnW.Crenshawto USNRC.EPRI(1999).RevisedRisk-InformedIn-ServiceInspectionProcedure.TR112657RevisionB-A,ElectricPowerResearchInstitute,PaloAlto,CA.Fleming,K.N.,B.O.Lydell,andD.Chrun(2011,July).DevelopmentofLOCAInitiatingEventFrequenciesforSouthTexasProjectGSI-191.TechnicalRe-port,KnFConsultingServices,LLC,Spokane,WA.French,S.(1985).Groupconsensusprobabilitydistributions:Acriticalsurvey.

InBayesianStatistics2,pp.183-197.North-Holland,Amsterdam.Genest,C.andJ.V.Zidek(1986).Combiningprobabilitydistributions:Acritiqueandannotatedbibliography.StatisticalScience1,114-148.Hasenbein,J.(2015,May).OrderRelationsforConcaveInterpolationMethods.TechnicalReport2015-001,TheUniversityofTexasatAustin,Austin,TX.Hindmarsh,A.C.(1983).ODEPACK,ASystematizedCollectionofODESolvers.Volume1ofComputing.R.S.Steplemanetal.(eds.).North-Holland,Amsterdam(1983):,pp.55-64.North-Holland,Amsterdam(1983).Hochreiter,L.E.(2005,December).Datacollectionofpipefailuresoccuringinstainlesssteelandcarbonsteelpiping.NucE597D-Project1,Pennsylvania StateUniversity.INEL(2007).Industry-AveragePerformanceforComponentsandInitiatingEventsatU.S.CommercialNuclearPowerPlants.NUREGCR-6928,Idaho NationalEngineeringLaboratory,IdahoFalls,ID.INL(1995,August).RELAP5/MOD3CodeManual.INEL95/0174,IdahoNationalLaboratory,IdahoFalls,ID.INL(2012,June).RELAP5-3DCodeManual.INEEL-EXT98-00834,IdahoNationalEngineeringLaboratory,IdahoFalls,ID.Johnson,D.(2015,June).PRACalculationsinSupportofRoverDWhitePaperDevelopment.LetterReportSTP-338116-O-02,STPSTI34176256,ABSG ConsultingInc.,Irvine,CA92602.Johnson,N.(1949).SystemsofFrequencyCurvesGeneratedbyMethodsofTranslations.Biometrika36,149-176.Letellier,B.(2011).Risk-InformedResolutionofGSI-191atSouthTexasProject.TechnicalReportRevision0,SouthTexasProject,Wadsworth,TX.Mans"eld,C.(2004).PeerReviewofExpertElicitation.MemoPreparedfortheEnvironmentalProtectionAgency,RTIInternational.Tuesday1 stMarch,2016:19:32,Page390of393 DRAFT BIBLIOGRAPHYMeyer,M.A.andJ.M.Booker(1990).ElicitingandAnalyzingExpertJudg-ment:APracticalGuide,NUREG/CR-5424,U.S.NuclearRegulatoryCom-

mission.Mosleh,A.(2011,October).TechnicalReviewofSTPLOCAFrequencyEstima-tionMethodology.LetterReportRevision0,UniversityofMaryland,College Park,MA.NEI(2004,May).PressurizedWaterReactorSumpPerformanceEvaluationMethodology.TechnicalReport04-07,NuclearEnergyInstitute,1776IStreet, Washington,DC.NRC(2011).RegulatoryGuide1.174:AnApproachforUsingProbabilisticRiskAssessmentInRisk-InformedDecisionsOnPlant-Speci"cChangesto theLicensingBasis,Revision2,NuclearRegulatoryCommission,Washington, DC.NRC(2012a,undated).FINALSAFETYEVALUATIONBYTHEOFFICEOFNUCLEARREACTORREGULATIONTOPICALREPORTWCAP-16793-NP,REVISION2EVALUATIONOFLONG-TERMCOOLINGCON-SIDERINGPARTICULATE,FIBROUSANDCHEMICALDEBRISINTHE RECIRCULATINGFLUID,PRESSURIZEDWATERREACTOROWNERS GROUPPROJECTNO.694.NRCSafetyEvaluation.NRC(2012b,August).GSI-191:Thermal-HydraulicResponseofPWRRe-actorCoolantSystemandContainmentstoSelectedAccidentSequenc.

NUREG/CR6770,LA-UR-015561,NuclearRegulatoryCommission,Wash-ington,DC.Ogden,N.,D.Morton,andJ.Tejada(2013,June).SouthTexasProjectRisk-InformedGSI-191Evaluation:FiltrationasaFunctionofDebrisMassonthe Strainer:FittingaParametricPhysics-BasedModel.Technicalreport,STP-RIGSI191-V03.06,TheUniversityofTexasatAustin,Austin,TX.Pan,Y.,E.Popova,andD.Morton(2013,January).ModelingandSamplingLOCAFrequencyandBreakSize.Stp-rigsi191-v03.02,TheUniversityof TexasatAustin,Austin,TX.Powell,G.T.(2013,November13).Supplement1toRevisedSTPPilotSubmit-talforaRisk-InformedApproachtoResolvingGenericSafetyIssue(GSI)-191 toSupersedeandReplacetheRevisedPilotSubmittal.ML13323A183,Letter fromGeraldT.PowelltotheUSNRCDocumentControlDesk;STPLetter

NOC-AE-13003043.Powell,G.T.(2015a,March25).DescriptionofRevisedRisk-InformedMethod-ologyandResponsestoRound2RequestsforAdditionalInformationRe-gardingSTPRisk-InformedGSI-191LicensingApplication.ML15091A440, LetterfromGeraldT.PowelltotheUSNRCDocumentControlDesk,NOC-

AE-15003220.Tuesday1 stMarch,2016:19:32,Page391of393 DRAFT BIBLIOGRAPHYPowell,G.T.(2015b,January).ResponsetoRequestforAdditionalInformationreUseofRELAP5inAnalysesforRisk-InformedGSI-191LicensingApplica-tion.ML14009A307,LetterfromGeraldT.PowelltotheUSNRCDocument ControlDesk.PWROG(2011,October).EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisintheRecirculatingFluid.WCAP 16793,Revision2,PressurizedWaterReactorOwnersGroup,Pittsburgh,PA.Rao,D.,C.andE.Haskin(1998,February).DrywellDebrisTransportStudy.NUREG/CR6369,USNRC,Washington,DC.STPNOC(2015,February4).STPRisk-InformedApproachtoGSI-191.ML15034A114,NRCpublicmeetingslides.TexasA&M(2013a,January).CoreBlockageThermal-HydraulicAnalysis.Cal-culationreportRevision2.1,STPSTI33719219,TexasA&MUniversity,Col-legeStation,Texas.TexasA&M(2013b,July).SouthTexasProjectPowerPlantRETRAN-RELAP5-3DConversionTables.CalculationreportRevision1.0, ML14029A533,TexasA&MUniversity,CollegeStation,Texas.TexasA&M(2013c,August).STPPowerPlantRELAP5-3DSteady-StateFi-nalConditions.CalculationreportRevision1.0,ML14029A533,TexasA&M University,CollegeStation,Texas.TexasA&M(2013d,July).STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.CalculationreportRevision1.0,ML14029A533,TexasA&M University,CollegeStation,Texas.Tregoning,R.,L.Abramson,andP.Scott(2008,April).EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElicitationProcess.NUREG/CR1829,NuclearRegulatoryCommission,Washngton,DC.Tregoning,R.,P.Scott,andA.Csontos(2008,April).EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElicitationProcess:Main Report(NUREG-1829).NUREG1829,NRC,Washington,DC.Uhle,J.L.(2005,December).Nrccommentsonpennsylvaniastateuniversitystudyofpipefailuredata.ML053410452,NRC,Washington,D.C.Vaghetto,R.andY.A.Hassan(2013).Studyofdebris-generatedcoreblock-agescenariosduringlossofcoolantaccidentsusingRELAP5-3D.NuclearEngineeringandDesign261(0),144-155.VonWinterfeldt,D.andW.Edwards(1986).DecisionAnalysisandBehavioralResearch.CambridgeUniversityPress,NewYork,NY.Tuesday1 stMarch,2016:19:32,Page392of393 DRAFT BIBLIOGRAPHYWake"eld,D.andD.Johnson(2013,January).SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume2,ProbabilisticRiskAnalysis:De-terminationofChangeinCoreDamageFrequencyandLargeEarlyRelease FrequencyDuetoGSI-191Issues.Technicalreport,STP-RIGSI191-VO2, Revision0,ABSGConsultingInc.Westinghouse(2011,April).TheNuclearDesignandCoreManagementoftheSouthTexasProjectUnit1NuclearPowerPlantCycle17.WCAP17399-P, WestinghouseElectricCompany,Pittsburgh,PA.Zolan,A.,J.Hasenbein,andJ.Tejada(2015a,June).FiberOperationsEngine.TechnicalReport2015-002,STPSTI34164169,TheUniversityof TexasatAustin,Austin,TX.Zolan,A.,J.Hasenbein,andJ.Tejada(2015b,July).RiskUnifyingFrequencyFunctional.TechnicalReport2015-003,STPSTI34164176,TheUniversity ofTexasatAustin,Austin,TX.Tuesday1 stMarch,2016:19:32,Page393of393 1 NRR-PMDAPEm Resource From:Harrison Albon <awharrison@STPEGS.COM>

Sent: Tuesday, March 01, 2016 8:46 PM To: Regner, Lisa Cc: Kee, Ernie; Blossom, Steven

Engen, Rob; Richards, Drew

Subject:

[External_Sender] STP GSI-191 RAI Cross Reference Attachments:

RAI Response Cross Reference.pdf Lisa, Here is the link to our DRAFT RAI cross-reference that we discussed in the public call on 2/18. We would like to discuss this at the staff's earliest convenience and follow that up with a docketed submittal. Note that the document is fairly easily navigated using the internal links.

https://stpegs.sharefile.com/d-scce1a0b0cdd4d1ca

Regards, Wayne Harrison

Hearing Identifier: NRR_PMDA Email Number: 2747 Mail Envelope Properties (A47D93CA-E20C-424E-8C78-673C44706144)

Subject:

[External_Sender] STP GSI-191 RAI Cross Reference Sent Date: 3/1/2016 8:46:25 PM Received Date: 3/1/2016 8:45:26 PM From: Harrison Albon Created By: awharrison@STPEGS.COM Recipients: "Kee, Ernie" <keeej@STPEGS.COM>

Tracking Status: None "Blossom, Steven" <sdblossom@STPEGS.COM>

Tracking Status: None "Engen, Rob" <rlengen@STPEGS.COM> Tracking Status: None "Richards, Drew" <amrichards@STPEGS.COM> Tracking Status: None "Regner, Lisa" <Lisa.Regner@nrc.gov>

Tracking Status: None Post Office: stpegs.com

Files Size Date & Time MESSAGE 374 3/1/2016 8:45:26 PM RAI Response Cross Reference.pdf 18583031 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date: Recipients Received:

DRAFTNRCReviewoftheSTPNOCLAR withResponsesTuesday1 stMarch,2016:19:32 DRAFTContents1NRCRequestsforAdditionalInformation181.1CrossreferencingRAIstoresponses................181.2RoverDimpacts............................18 1.3Round1RAIs............................341.3.1APLAB............................341.3.1.1CASAGRANDE.................341.3.1.2RESULTSINTERPRETATION.........451.3.2ACRB.............................481.3.3EMCB.............................501.3.4EPNB.............................511.3.5ESGB.............................531.3.5.1Chemical..................531.3.5.2Coatings......................591.3.6SCVB.............................611.3.7SNPB.............................641.3.8SRXB.............................651.3.9SSIB..............................661.3.10STSB.............................811.4Round2RAIs............................831.4.1APLAB............................831.4.2EMCB.............................881.4.3ESGB.............................891.4.4SCVB.............................941.4.5SNPB.............................1011.4.6SSIB..............................1031.4.7STSB.............................1112RAIResponses(Round1)1142.1ML14149A434,Firstsetofresponses................1142.1.1APLABResponses......................1142.1.1.1APLAB,CASAGrande,LOCAFrequencies:Ques-tion1........................1142.1.1.2APLAB,CASAGrande,LOCAFrequencies:Ques-tion3........................1152.1.1.3APLAB,CASAGrande,LOCAFrequencies:Ques-tion4........................1162.1.1.4APLAB,CASAGrande,toPRAInterface-Gen-eral:Question1a..................116 1

DRAFT CONTENTS2.1.1.5APLAB,CASAGrande,toPRAInterface-Gen-eral:Question1b..................1162.1.1.6APLAB,CASAGrande,toPRAInterface-Gen-eral:Question3..................1172.1.1.7APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4a..................1172.1.1.8APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4b..................1182.1.1.9APLAB,CASAGrande,toPRAInterface-Gen-eral:Question4c..................1182.1.1.10APLAB,CASAGrande,toPRAInterface-Gen-eral:Question5..................1192.1.1.11APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6a..................1192.1.1.12APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6b..................1192.1.1.13APLAB,CASAGrande,toPRAInterface-Gen-eral:Question6c..................1202.1.1.14APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1................1202.1.1.15APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2................1212.1.1.16APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4a...............1212.1.1.17APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4b...............1222.1.1.18APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6................1242.1.1.19APLAB,STPPRAModel-PRAScope:Ques-tion1........................1252.1.1.20APLAB,ResultsInterpretation-Quanti"cation:Question1a.....................1262.1.1.21APLAB,ResultsInterpretation-Quanti"cation:Question1b....................1262.1.1.22APLAB,ResultsInterpretation-Quanti"cation:Question2.....................1262.1.1.23APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question2..................1562.1.2ESGBResponses.......................1572.1.2.1ESGB,ChemicalQuestion12......1572.1.2.2ESGB,ChemicalQuestion13a.....1582.1.2.3ESGB,ChemicalQuestion13b.....1592.1.2.4ESGB,ChemicalQuestion13c.....1592.1.2.5ESGB,ChemicalQuestion19......1612.1.3SRXBResponses.......................1612.1.3.1SRXB,Question1.................1612.1.3.2SRXB,Question2.................1612.1.3.3SRXB,Question3.................161Tuesday1 stMarch,2016:19:32,Page2of393 DRAFT CONTENTS2.1.3.4SRXB,Question4.................1612.1.3.5SRXB,Question5a................1612.1.3.6SRXB,Question5b................1622.1.3.7SRXB,Question5c................1622.1.3.8SRXB,Question6.................1632.1.3.9SRXB,Question7a................1632.1.3.10SRXB,Question7b................1632.1.3.11SRXB,Question8.................1642.1.3.12SRXB,Question9.................1642.1.4SSIBResponses........................1662.1.4.1SSIB,ZOI:Question1...............1662.1.4.2SSIB,DebrisCharacteristics:Question2....1662.1.4.3SSIB,Transport:Question5...........1662.1.4.4SSIB,Transport:Question9...........1672.1.4.5SSIB,Transport:Question11a..........1672.1.4.6SSIB,Transport:Question11b..........1672.1.4.7SSIB,Transport:Question11c..........1682.1.4.8SSIB,Transport:Question11d..........1682.1.4.9SSIB,Transport:Question11e..........1682.1.4.10SSIB,Transport:Question13...........1692.1.4.11SSIB,NPSHandDegasi"cation:Question29..1772.1.5STSBResponses.......................1772.1.5.1STSB:Question1.................1772.1.5.2STSB:Question2.................1782.1.5.3STSB:Question3.................1792.2ML14178A481,Secondsetofresponses...............1802.2.1APLABResponses......................1802.2.1.1APLAB,CASAGrande-LOCAFrequencies:Question2.....................1802.2.1.2APLAB,STPPRAModel-General:Question2180 2.2.1.3APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5................1802.2.2ESGBResponses.......................1812.2.2.1ESGB,ChemicalQuestion3.......1812.2.2.2ESGB,ChemicalQuestion7.......1822.2.2.3ESGB,ChemicalQuestion11a.....1862.2.2.4ESGB,ChemicalQuestion11b.....1862.2.2.5ESGB,ChemicalQuestion17......1872.2.2.6ESGB,ChemicalQuestion20......1882.2.2.7ESGB,ChemicalQuestion22a.....1892.2.2.8ESGB,ChemicalQuestion22b.....1912.2.3SCVBResponses.......................1922.2.3.1SCVB,Question:1a................1922.2.3.2SCVB,Question:1b................1922.2.3.3SCVB,Question:2a................1922.2.3.4SCVB,Question:2b................1922.2.3.5SCVB,Question:3a................1932.2.3.6SCVB,Question:3b................193Tuesday1 stMarch,2016:19:32,Page3of393 DRAFT CONTENTS2.2.3.7SCVB,Question:3c................1962.2.3.8SCVB,Question:4a................1962.2.3.9SCVB,Question:4b................1972.2.3.10SCVB,Question:4c................1972.2.3.11SCVB,Question:5................1972.2.3.12SCVB,Question:6................1972.2.3.13SCVB,Question:7................1972.2.3.14SCVB,Question:8................1982.2.3.15SCVB,Question:9a................1982.2.3.16SCVB,Question:9b................1992.2.4SNPBResponses.......................1992.2.4.1SNPB,Question:1a................1992.2.4.2SNPB,Question:1b................2012.2.4.3SNPB,Question:1c................2032.2.4.4SNPB,Question:1d................2032.2.4.5SNPB,Question:1e................2032.2.4.6SNPB,Question:1f................2052.2.4.7SNPB,Question:1g................2052.2.4.8SNPB,Question:1h................2052.2.4.9SNPB,Question:1i................2052.2.4.10SNPB,Question:1j................2052.2.4.11SNPB,Question:1k................2072.2.4.12SNPB,Question:1l................2072.2.4.13SNPB,Question:1m...............2072.2.4.14SNPB,Question:2a................2082.2.4.15SNPB,Question:2b................2082.2.4.16SNPB,Question:2c................2082.2.4.17SNPB,Question:2d................2082.2.4.18SNPB,Question:3.................2092.2.4.19SNPB,Question:5.................2102.2.5SSIBResponses........................2112.2.5.1SSIB,Transport:Question12...........2112.2.5.2SSIB,HeadLossandChemicalBump-up:Question25a....................2112.2.5.3SSIB,HeadLossandChemicalBump-up:Question25b....................2122.2.5.4SSIB,HeadLossandChemicalBump-up:Question26a....................2122.2.5.5SSIB,HeadLossandChemicalBump-up:Question26b....................2122.2.5.6SSIB,HeadLossandChemicalBump-up:Question26c....................2122.2.5.7SSIB,HeadLossandChemicalBump-up:Question26d....................2132.2.5.8SSIB,HeadLossandChemicalBump-up:Question26e....................2152.2.5.9SSIB,HeadLossandChemicalBump-up:Question26f....................217Tuesday1 stMarch,2016:19:32,Page4of393 DRAFT CONTENTS2.2.5.10SSIB,NPSHandDegasi"cation:Question30..2172.2.5.11SSIB,NPSHandDegasi"cation:Question31..217 2.2.5.12SSIB,NPSHandDegasi"cation:Question32..217 2.2.5.13SSIB,NPSHandDegasi"cation:Question34..218 2.2.5.14SSIB,NPSHandDegasi"cation:Question35..218 2.2.5.15SSIB,In-VesselandBoricAcidPrecipitation:Ques-tion37.......................2182.2.5.16SSIB,DebrisBypass:Question39a.......2192.2.5.17SSIB,DebrisBypass:Question39b.......2212.2.5.18SSIB,DebrisBypass:Question39c........2212.2.5.19SSIB,DebrisBypass:Question39d.......2222.2.5.20SSIB,DebrisBypass:Question39e........2222.2.5.21SSIB,DebrisBypass:Question39f........2222.2.5.22SSIB,DefenseinDepthandMitigativeMeasures:Question41a....................2232.2.5.23SSIB,DefenseinDepthandMitigativeMeasures:Question41b....................2242.2.5.24SSIB,DefenseinDepthandMitigativeMeasures:Question41c....................2242.2.5.25SSIB,DefenseinDepthandMitigativeMeasures:Question41d....................2242.3ML14202A045,Thirdsetofresponses...............2242.3.1APLABResponses......................2242.3.1.1APLAB,CASAGrande-General:Question1a224 2.3.1.2APLAB,CASAGrande-General:Question1b235 2.3.1.3APLAB,CASAGrande-General:Question1c235 2.3.1.4APLAB,CASAGrande-PlantCon"guration:Question1a.....................2352.3.1.5APLAB,CASAGrande-PlantCon"guration:Question1b....................2352.3.1.6APLAB,CASAGrande-PlantCon"guration:Question2a.....................2362.3.1.7APLAB,CASAGrande-PlantCon"guration:Question2b....................2362.3.1.8APLAB,CASAGrande-PlantCon"guration:Question3a.....................2372.3.1.9APLAB,CASAGrande-PlantCon"guration:Question3b....................2382.3.1.10APLAB,CASAGrande-PlantCon"guration:Question3c.....................2382.3.1.11APLAB,CASAGrandetoPRAInterface-General:Question2a.....................2382.3.1.12APLAB,CASAGrandetoPRAInterface-General:Question2b....................2382.3.1.13APLAB,STPPRAModel-General:Question1.240 2.3.1.14APLAB,STPPRAModel-General:Question3.240 2.3.1.15APLAB,STPPRAModel-SuccessCriteria:Ques-tion1........................241Tuesday1 stMarch,2016:19:32,Page5of393 DRAFT CONTENTS2.3.1.16APLAB,STPPRAModel-SuccessCriteria:Ques-tion2a.......................2422.3.1.17APLAB,STPPRAModel-SuccessCriteria:Ques-tion2b.......................2422.3.1.18APLAB,STPPRAModel-SuccessCriteria:Ques-tion2c.......................2422.3.1.19APLAB,STPPRAModel-SuccessCriteria:Ques-tion3a.......................2432.3.1.20APLAB,STPPRAModel-SuccessCriteria:Ques-tion3b.......................2442.3.1.21APLAB,STPPRAModel-SuccessCriteria:Ques-tion3c.......................2442.3.1.22APLAB,STPPRAModel-SuccessCriteria:Ques-tion3d.......................2452.3.1.23APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3a..................2452.3.1.24APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3b..................2452.3.1.25APLAB,STPPRAModel-HumanReliabilityAnal-ysis:Question3c..................2462.3.1.26APLAB,STPPRAModel-PRAScope:Question2246 2.3.1.27APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1a..................2462.3.1.28APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1b..................2462.3.1.29APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question1c..................2472.3.1.30APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question3..................2472.3.1.31APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4a..................2482.3.1.32APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4b..................2482.3.1.33APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4c..................2492.3.1.34APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question4d..................2492.3.1.35APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question5..................2492.3.1.36APLAB,ResultsInterpretation-UncertaintyAnal-ysis:Question6..................2492.3.2ACRBResponses.......................2512.3.2.1ARCB:Question1.................2512.3.2.2ARCB:Question2.................2512.3.2.3ARCB:Question3.................2512.3.3EMCBResponses......................2512.3.3.1ECMB,Question1................2512.3.3.2EMCB,Question2................252Tuesday1 stMarch,2016:19:32,Page6of393 DRAFT CONTENTS2.3.4ENPBResponses.......................2522.3.4.1ENPB,Question1.................2522.3.4.2ENPB,Question2.................2532.3.4.3ENPB,Question3.................2532.3.4.4ENPB,Question4.................2542.3.4.5ENPB,Question5.................2542.3.4.6ENPB,Question6a................2552.3.4.7ENPB,Question6b................2552.3.5ESGBResponses.......................2562.3.5.1ESGB,ChemicalQuestion1a......2562.3.5.2ESGB,ChemicalQuestion1b......2572.3.5.3ESGB,ChemicalQuestion1c......2572.3.5.4ESGB,ChemicalQuestion1d......2592.3.5.5ESGB,ChemicalQuestion2.......2602.3.5.6ESGB,ChemicalQuestion4.......2612.3.5.7ESGB,ChemicalQuestion5.......2612.3.5.8ESGB,ChemicalQuestion6.......2642.3.5.9ESGB,ChemicalQuestion8.......2652.3.5.10ESGB,ChemicalQuestion9.......2652.3.5.11ESGB,ChemicalQuestion10......2662.3.5.12ESGB,ChemicalQuestion14a.....2682.3.5.13ESGB,ChemicalQuestion14b.....2682.3.5.14ESGB,ChemicalQuestion14c.....2702.3.5.15ESGB,ChemicalQuestion15......2702.3.5.16ESGB,ChemicalQuestion16......2712.3.5.17ESGB,ChemicalQuestion18a.....2722.3.5.18ESGB,ChemicalQuestion18b.....2722.3.5.19ESGB,ChemicalQuestion18c.....2722.3.5.20ESGB,ChemicalQuestion21......2732.3.5.21ESGB,Coatings:Question1...........2732.3.5.22ESGB,Coatings:Question2...........2742.3.5.23ESGB,Coatings:Question3...........2742.3.5.24ESGB,Coatings:Question4...........2742.3.5.25ESGB,Coatings:Question5...........2772.3.5.26ESGB,Coatings:Question6a..........2802.3.5.27ESGB,Coatings:Question6b..........2802.3.5.28ESGB,Coatings:Question6c...........2802.3.5.29ESGB,Coatings:Question7...........2812.3.5.30SNPB,Question4.................2832.3.6SSIBResponses........................2852.3.6.1SSIB,DebrisCharacteristics:Question3....2852.3.6.2SSIB,Transport:Question4...........2852.3.6.3SSIB,Transport:Question6a...........2882.3.6.4SSIB,Transport:Question6b..........2882.3.6.5SSIB,Transport:Question6c...........2902.3.6.6SSIB,Transport:Question6d..........2932.3.6.7SSIB,Transport:Question6e...........2972.3.6.8SSIB,Transport:Question7a...........301Tuesday1 stMarch,2016:19:32,Page7of393 DRAFT CONTENTS2.3.6.9SSIB,Transport:Question7b..........3022.3.6.10SSIB,Transport:Question7c...........3032.3.6.11SSIB,Transport:Question7d..........3032.3.6.12SSIB,Transport:Question7e...........3042.3.6.13SSIB,Transport:Question7f...........3042.3.6.14SSIB,Transport:Question8a...........3042.3.6.15SSIB,Transport:Question8b..........3052.3.6.16SSIB,Transport:Question8c...........3052.3.6.17SSIB,Transport:Question8d..........3052.3.6.18SSIB,Transport:Question8e...........3052.3.6.19SSIB,Transport:Question10...........3052.3.6.20SSIB,HeadLossandChemicalBumpUp:Question14..................3062.3.6.21SSIB,HeadLossandChemicalBumpUp:Question15a.................3072.3.6.22SSIB,HeadLossandChemicalBumpUp:Question15b.................3072.3.6.23SSIB,HeadLossandChemicalBumpUp:Question15c.................3072.3.6.24SSIB,HeadLossandChemicalBumpUp:Question15d.................3092.3.6.25SSIB,HeadLossandChemicalBumpUp:Question16a.................3102.3.6.26SSIB,HeadLossandChemicalBumpUp:Question16b.................3112.3.6.27SSIB,HeadLossandChemicalBumpUp:Question16c.................3122.3.6.28SSIB,HeadLossandChemicalBumpUp:Question16d.................3122.3.6.29SSIB,HeadLossandChemicalBumpUp:Question17a.................3132.3.6.30SSIB,HeadLossandChemicalBumpUp:Question17b.................3142.3.6.31SSIB,HeadLossandChemicalBumpUp:Question17c.................3142.3.6.32SSIB,HeadLossandChemicalBumpUp:Question17d.................3142.3.6.33SSIB,HeadLossandChemicalBumpUp:Question17e.................3142.3.6.34SSIB,HeadLossandChemicalBumpUp:Question17f..................3152.3.6.35SSIB,HeadLossandChemicalBumpUp:Question18a.................3152.3.6.36SSIB,HeadLossandChemicalBumpUp:Question18b.................3152.3.6.37SSIB,HeadLossandChemicalBumpUp:Question18c.................316Tuesday1 stMarch,2016:19:32,Page8of393 DRAFT CONTENTS2.3.6.38SSIB,HeadLossandChemicalBumpUp:Question18d.................3172.3.6.39SSIB,HeadLossandChemicalBumpUp:Question18e.................3172.3.6.40SSIB,HeadLossandChemicalBumpUp:Question19..................3172.3.6.41SSIB,HeadLossandChemicalBumpUp:Question20..................3182.3.6.42SSIB,HeadLossandChemicalBumpUp:Question21a.................3192.3.6.43SSIB,HeadLossandChemicalBumpUp:Question21b.................3192.3.6.44SSIB,HeadLossandChemicalBumpUp:Question21c.................3192.3.6.45SSIB,HeadLossandChemicalBumpUp:Question21d.................3202.3.6.46SSIB,HeadLossandChemicalBumpUp:Question22..................3202.3.6.47SSIB,HeadLossandChemicalBumpUp:Question23..................3212.3.6.48SSIB,HeadLossandChemicalBumpUp:Question24..................3212.3.6.49SSIB,HeadLossandChemicalBumpUp:Question27..................3232.3.6.50SSIB,HeadLossandChemicalBumpUp:Question28..................3232.3.6.51SSIB,NPSHandDegasi"cation:Question33..324 2.3.6.52SSIB,NPSHandDegasi"cation:Question36..325 2.3.6.53SSIB,NPSHandDegasi"cation:Question38..327 2.3.6.54SSIB,DefenseInDepthandMitigativeMeasures:Question40.....................3272.3.6.55SSIB,DefenseInDepthandMitigativeMeasures:Question42.....................3293ResponsetoEPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6330 3.1EPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6.................................3303.2ConsistencyofLOCAFrequencyEstimates:GSI-191SubmittalandRI-ISI...............................3313.3EstimateofCDF..........................3313.4FrequenciesofSmall,Medium,andLargeBreaks.........3323.5ProbabilityDistributionsGoverningBreakSizeandWeldCase.3324RAIResponses(Round2)3374.1ML15091A440,APLABResponses.................3374.1.1Question1:ProjectQualityAssurance...........3374.1.2Question2:ProjectQualityAssurance...........337Tuesday1 stMarch,2016:19:32,Page9of393 DRAFT CONTENTS4.1.3Question3:ProjectQualityAssurance...........3384.1.4Question4:ProjectQualityAssurance...........3384.1.5Question1:TreatmentofUnanalyzedPlantConditions.344 4.1.6Question7:HumanReliabilityAnalysis..........3444.1.7Question1:KeyAssumptions/KeySourcesofUncertainty344 4.1.8Question1:ValidityofAssumptiononPumpCon"gurations345 4.1.9Question7:CASAGrandetoPRAInterface.......3454.1.10Question1:FidelitybetweenRELAPSimulationsandCASAGrande............................3454.1.11Question1:State-of-KnowledgeCorrelation........3464.1.12Question1:SelectionofJohnsonParameters.......3464.2ML15091A440,EMCBResponses..................3464.2.1Question2..........................3464.3ML15091A440,ESGBResponses..................3464.3.1Question23:Chemical...............3464.3.2Question24:Chemical...............3474.3.3Question25:Chemical...............3474.3.4Question26:Chemical...............3474.3.5Question27:Chemical...............3474.3.6[ML15091A440]Question28:Chemical......3474.3.7Question29:Chemical...............3484.3.8Question30:Chemical...............3484.3.9Question31:Chemical...............3484.3.10Question32:Chemical...............3484.3.11Question33:Chemical...............3484.3.12Question34:Chemical...............3494.3.13Question8:Coatings.....................3504.3.14Question9:Coatings.....................3504.3.15Question10:Coatings....................3504.4ML15091A440,SCVBResponses..................3504.4.1Question10..........................3504.4.2ML15246A128,Question11.................3534.4.3ML15246A128,Question12(1)...............3534.4.4ML15246A128,Question12(2)...............3544.4.5ML15246A128,Question12(3)...............3544.4.6ML15246A128,Question12(4)...............3544.4.7ML15246A128,Question12(4)a...............3544.4.8ML15246A128,Question12(4)b...............3544.4.9ML15246A128,Question13.................3554.4.10ML15246A128,Question14(1)...............3554.4.11ML15246A128,Question14(2)...............3554.4.12ML15246A128,Question14(3)...............3554.4.13ML15246A128,Question14(4)...............3554.4.14ML15246A128,Question14(5)...............3554.4.15ML15246A128,Question14(5)(a)..............3554.4.16ML15246A128,Question14(5)(b)..............3564.4.17ML15246A128,Question15.................3564.4.18ML15246A128,Question16(1)...............356Tuesday1 stMarch,2016:19:32,Page10of393 DRAFT CONTENTS4.4.19ML15246A128,Question16(2)...............3564.4.20ML15246A128,Question16(3)...............3564.4.21ML15246A128,Question16(4)...............3564.4.22ML15246A128,Question16(5)...............3574.4.23ML15246A128,Question16(5)(a)..............3574.4.24ML15246A128,Question16(5)(b)..............3574.4.25ML15246A128,Question17.................3574.4.26ML15246A128,Question18(a)(b)(c)(d).........3574.5ML15091A440,SNPBResponses..................3574.5.1Question6..........................3574.5.2Question7..........................3584.5.3Question8..........................3584.5.4Question9..........................3584.5.5Question10..........................3584.6ML15091A440,SSIBResponses...................3584.6.1Question43..........................3584.6.2Question44..........................3594.6.3Question45..........................3644.6.4Question46..........................3674.6.5Question47..........................3684.6.6Question48..........................3684.6.7Question49..........................3694.6.8Question50..........................3694.6.9Question51..........................3694.6.10Question52..........................3704.6.11Question53..........................3704.6.12Question54..........................3714.6.13Question55..........................3724.6.14Question55a.........................3724.6.15Question56..........................3724.6.16Question57(a)........................3724.6.17Question57(b)........................3724.6.18Question57(c)........................3724.6.19Question57(d)........................3734.6.20Question57(e)........................3734.6.21Question57(f)........................3744.6.22Question58..........................3744.6.23Question59..........................3754.6.24Question60..........................3824.6.25Question61..........................3834.6.26Question62..........................3854.6.27Question63..........................3854.6.28Question64..........................3854.6.29Question65..........................3854.6.30Question66..........................3864.7ML15091A440,STSBResponses..................3864.7.1Question4..........................386Tuesday1 stMarch,2016:19:32,Page11of393 DRAFT CONTENTS AFWAuxiliaryFeedWater BAPBoricAcidPrecipitation BAPBoricAcidPrecipitation BBCoreBarrelBypass BWRBoilingWaterReactor CADComputerAidedDesign CASAContainmentAccidentStochasticAnalysis(CASA)Grande CCFLCounterCurrentFlowLimit CCWComponentCoolingWaterSystem CDFCoreDamageFrequency CFDComputational"uiddynamicsCDFChangeincoredamagefrequencyaboveabaselinelevelLERFChangeinlargeearlyreleasefrequencyaboveabaselinelevel CHRSContainmentHeatRemovalSystemisaengineeredsafetysystemtoremovedecayheatloadfromthecontainmentafterreactor shutdown cdfCumulativeDistributionFunction:

F (x)=xf (t)dt,where f (*)isthepdf CLBColdLegBreak CSSContainmentSpraySystem DEGBDouble-EndedGuillotineBreak DID Defense-in-Depth ECWEssentialCoolingWaterSystem EOPsEmergencyOperatingProcedures ECCSEmergencyCoreCoolingSystem EOPEmergencyOperatingProcedures ESDEventSequenceDiagram FAFuelAssembly.Severalfuelassembliesareloadedinthereactorvesseltoformthereactorcore FAFuelAssemblyTuesday1 stMarch,2016:19:32,Page12of393 DRAFT CONTENTS FIDOEFIberOperationsEngine;applicationthatsolves"bermassconservation FiDOEFiberOperationsEngine GDCGeneralDesignCriteria(AppendixAtoPart50ofthecodeoffederalregulations)GL2004-02NRCGenericLetter2004-02 GRAGenerationRiskAssessment GSI-191GenericSafetyIssue191-theNRCGenericSafetyIssuenumber 191 GSI-191GenericSafetyIssue191 HHSIHighHeadSafetyInjection HLBHotLegBreak HLSOHotLegSwitchOver HRAHumanReliabilityAnalysis IOZInorganiczinc INLIdahoNationalLaboratory ISIASMESectionXIInserviceInspectionisanASMESectionXIprogramthat,amongotherthings,veri"estheweldintegrityin criticalpiping LARLicenseAmendmentRequest LANLocalAreaNetwork LBLicensingBasisisthecollectionofcommitmentsandrequirementsthatlicenseemakestotheregulatoryauthority(in thiscase,theNRC)overthecourseoftime LBBLeakbeforebreakisaproposedlicensingapproachthatreliesontheobservationthatpriortoacatastrophicfailureinlargebore piping,asmall,detectable"owinitiatesLDFGLowDensityFiberglass(suchasNUKON TM)LERLicenseeEventReport LERFLargeEarlyReleaseFrequency LHSLatinHypercubeSamplingisasimulation-basedprocedurethatgeneralizesthenotionofstrati"edsamplingtomultiple dimensionsandyieldsanunbiasedpointestimate,while attemptingtoreducevarianceoftheestimatorovernaiveMonte CarlosamplingTuesday1 stMarch,2016:19:32,Page13of393 DRAFT CONTENTS LHSILowHeadSafetyInjection LLOCALargeBreakLossofCoolantAccident LOCALossofCoolantAccident LOSPLossofPower LLRFLargeLateReleaseFrequencyLWRLightWaterReactor MFWMainFeedWater MLOCAMediumBreakLossofCoolantAccident NLHSNonuniformLatinHypercubeSamplingisavariantoftheLHSschemethatallowsthesupportofeachmarginaldistributionto bepartitionedintocellswithnon-equalprobabilities NPSHNetPositiveSuctionHead NOPNormalOperatingPressure NOTNormalOperatingTemperature NPSHANetPositiveSuctionHeadAvailable NPSHRNetPositiveSuctionHeadRequiredNPSHmargin (*)Thetime-dependentNPSHmargin;i.e.,thedbetweentheNPSHavailableandtheNPSHrequiredNRCTheNuclearRegulatoryCommission NSSSNuclearSteamSupplySystemisthenuclearreactor,piping,pumps,steamgenerators,pressurizer,andauxiliaryequipment associatedwithoperationandcontrolofthereactorsystem NSSSNuclearSteamSupplySystempdfAprobabilitydensityfunctionspeci"estherelativelikelihoodthatacontinuousrandomvariabletakesonaspeci"cvalue.

Whenintegratedoveraregion,representinganevent,thepdf yieldstheprobabilitymassassociatedwiththeevent,asinthe probabilityofobservingabreakdiameterbetween2-inchesand 5-inches PHSAProbabilisticSeismicHazardAnalysisistheprobabilisticstudyofseismiceventsonsystems,structures,andcomponentsto obtainfailurelikelihoods PCTPeakCladdingTemperature PNGPortableNetworkGraphicsTuesday1 stMarch,2016:19:32,Page14of393 DRAFT CONTENTS PRAProbabilisticRiskAssessment PWRPressurizedWaterReactorPWROGPressurizedWaterReactorOwnersGroup PWSCCPrimaryWaterStressCorrosionCracking RBDReliabilityBlockDiagram RBMKHighPowerChannel-typeReactorRCBReactorContainmentBuildingRCFCTheReactorContainmentFanCoolersRCPReactorCoolantPumpRCSReactorCoolantSystemRG1.174RegulatoryGuide1.174isaregulatoryguidancedocumentthatdescribestheoverallmethodologytoquantifyriskusingthePRA togetherwithdeterministically-basedcriteriatoevaluatethe acceptabilityofaparticularchange.Thequantitativerisk measuresareCDFandLERF.Theriskisdeemedtobevery smallwhenthechangeincreasesCDFlessthan10 6andtheLERFlessthan10 7 RHRResidualHeatRemovalSystem RMIRe"ectiveMetalInsulationisa"tted,rigidinsulationthatusesmetalradiationheatshieldsanddeadairspacetoreduceheat

loss RMSRecordsManagementSystemistheSTPNOCdocumentstorageandretrievalsystemmeetingtherequirementsofRegulatory Guide1.33,Revision2,QualityAssuranceProgram Requirements(Operation)

RMTSRiskManagedTechnicalSpeci"cationstheallowedoutagetimeforrisksigni"cantequipmentderivedfromthecon"gurationrisk duringtheoutagetimeRoverDRisk-informedOverDeterministicRUFFRiskUncertaintyFrequencyFunction.TheapplicationforinterpolatingNUREG1829frequencies RVReactorvesselandreactorcoreRWSTRefuelingWaterStorageTank RYReactorYear SISafetyInjectionSystemTuesday1 stMarch,2016:19:32,Page15of393 DRAFT CONTENTS SGSteamGenerator SLOCASmallBreakLossofCoolantAccident STPSouthTexasProject STLstereolithography"leformat STPNOCTheSTPNuclearOperatingCompany TSPTrisodiumphosphate(NA 3 PO 4*12H 2O)sumpwaterpHchemical ZOIZoneofIn"uence DbreakLOCAbreakdiameter D iThebreaksizeatanyparticularlocation(locationsindexedby i=1 , 2 ,...,N)Dsmall icorrespondstothesmallestbreaksizeatanyparticularlocationthatproducesmore"nesintheECCSsumpthanthetested amount D pipePipediameter F DbreaklweldcaseIstheconditionaldistributiongoverningtherandombreak diameter, Dbreak,giventhatabreakoccursataspeci"edweldtype/case f iFrequencyassociatedwiththebreakdiameter, D i fsmallest iFrequencyassociatedwiththebreakdiameter, D i H (*)ThefunctionbasedonNUREG-6224usedincomputingheadlossacrossECCSsumpstrainer kTheindex, k=1 , 2 ,...,K,forbreakssampledataparticularlocation(i)Isthescenario-dependentazimuthalangleofthebreakaroundthepipech (*)Isthetime-andscenario-dependentchemicalbump-upfactorusedincomputingheadlossacrossECCSsumpstrainerThefractionoftotaltime-dependentECCS"ow(Q(t))thatpassesthroughtrainsECCSstrainerandarrivesintheRCS.Theindex=A,B,Creferstotheassociatedtrain w iWeightassociatedwithascenariointherisk-informedcategory UQUncertaintyQuanti"cation LHSLatinHypercubeSamplingTuesday1 stMarch,2016:19:32,Page16of393 DRAFT CONTENTS LPLowerPlenum IEInitiatingEvent DEGBDoubleEndedGuillotineBreak ZOIZoneOfIn"uence CFPConditionalFailureProbabilityTuesday1 stMarch,2016:19:32,Page17of393 DRAFTPart1NRCRequestsforAdditionalInformationThereweretworoundsofquestionsontheLAR.Approximately259individualquestionswereinthe"rstroundandabout90individualquestionsinthesecond round.TheRoverDmethodologygreatlyreducedtheworkrequiredtoanswer theRAIs.ManyoftheRAIresponsesrefertoRoverD.WhereRoverDhaspre-emptedthequestion,thisisnotedintheleftmargin,forexample,RoverD deletes.Otherwise,wehavenotedwhereaquestionstillapplieswithaleftmarginnotesuchasRoverDrequired

.1.1CrossreferencingRAIstoresponsesWecross-referencedtheRAIresponsestothequestions.Thecrossreferencesarelinkedtotheanswersinthemargins(forexample,Response,Pg.223).

Theresponsesarelikewisecrossreferencedtotherespectivequestion.There-sponsesareorganizedintwomajorsections,Round1RAIsandRound2RAIs.

TheRound1responsesarealsogroupedaccordingthethreesets(FirstSet, SecondSet,andThirdSet)withtheexceptionoftheonesansweredinthe AugustLARsupplement.ThosearegroupedwiththeRound2responses.TheRAIsareintwosections,the"rstroundandthesecondround.WitheachRAI,theresponseiscross-referencedwithmarginnotesasdescribedabove.1.2RoverDimpactsTheRoverDmethodologyisdesignedtoreducetheamountofworkrequiredto developandreviewthebasisformakingdecisionsregardingtheriskassociated withdebrisincontainment.OverthethreeyearssincetheJanuary2013submit-taloftheSTPLAR,manyquestionswereraisedconcerningtherelativelynew andinnovativemethodologythatusedUQtoobtainconditionalfailureprob-abilitiesthatwereinturn,usedintheProbabilisticRiskAssessment(PRA)to computethemetrics,CDF,Changeincoredamagefrequencyaboveabaseline level(,LargeEarlyReleaseFrequency(LERF),andChangeinlarge earlyreleasefrequencyaboveabaselinelevelInhere,thecollectedquestionsraisedbytheTheNuclearRegulatoryCom-mission(NRC)inthecourseofreviewaresummarizedalongwithresponses.In SeveralofthequestionsandresponsesarenolongerrelevanttotheRoverD-based LAR.Inherewesummarizewhatquestionsandresponsesrelatedtothe2013 versionoftheLARtheRoverDmethodologyremovesfromreviewscopeandad-ditionalsupport.Thefollowinglistprovidesdetaileddescriptionsofcomments (primarilythoserelatedtoRemoved)toitemsusedintheBasissummarycolumninTable1.1.

18 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.ParametricdistributionsTheUQprocessrequirescharacterizationofparameterdistributionsusedinsamplingstrategiesforestimatingandpropagatingphysicalmodelre-sponses.RoverDinsteadusesatestdesignedtoboundtheuncertainty associatedwithEmergencyCoreCoolingSystem(ECCS)strainerhead

losses.2.Thermal-hydraulicsimulations(a)InordertocomprehensivelyestimatetheReactorContainmentBuild-ing(RCB)andReactorCoolantSystem(RCS)responsestod entbreakscenariosandplantstates(pumpingcombinations),several thermal-hydraulicsimulationsarerequiredtoestimatethetempera-tureandpressurehistoriesintheRCBandRCSusingcoupledmod-elsoftheRCBandRCS.RoverDreliesontheexistingTheSTP NuclearOperatingCompany(STPNOC)license-basisRCBanalysis forstrainerperformanceparameters;boundingtestdataandbound-ingthermal-hydraulicanalysistoensureadequatecorecooling.The pumpstatesareboundedfor"berpenetrationandcollection(single trainandtwoormoretrainsconsidered).(b)IntheSouthTexasProject(STP)2013LAR,considerationwasre-quiredforvariousscenariosthatwouldrepresentthepossibilitythat boricacidprecipitatescouldblockadequatecore"ow.TheRoverD methodologyreliesonsensitivitiesshowingthatsolittle"berbuilds uponthecoreincoldlegbreaksthatmixingwiththelowerplenum wouldnotbeinhibitedandthereforetheexistingcalculationmixing assumptionismet.(c)BoththeRoverDmethodologyandthefullrisk-informedmethodol-ogyusedintheSTP2013LARrequirethatadequatecorecoolingis providedbytheECCS.Suchconsiderationsincludeboricacidprecip-itation(seeabove)andanyotherdebrismayonfuelcooling otherthan"owblockage.3.PRAlevelofdetail(a)InordertosupportthemanypossibleECCSandContainmentSpraySystem(CSS)con"gurations,thePRAneededtohaveseveraltop eventsadded.Thenecessary"delityandconcomitantmodelsupport detailneededtoaccuratelyrepresentallpossiblecon"gurationsisrel-ativelycomplex.Somereductioncanberealizedbyboundinganal-yses;howevertheprocessusedresultedinmanyRAIs.TheRoverD methodologyavoidsextensiverelianceonthePRAandinfact,uses whatcouldeelybethoughtofasaLOCADebrisinitiating eventfrequencyasaboundingratherthandetailedmodeling inthePRA.Similarly,thePRAmodelofrecordisusedtoevalu-atetheLERFusingtheratioofLERFconditionalonECCSsump screenfailureforLargeBreakLossofCoolantAccident(LLOCA) andCDFconditionalonsumpscreenfailureinLLOCA.Tuesday1 stMarch,2016:19:32,Page19of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Humanreliabilityanalysisisrequiredforthevariousactionsassumedinthedetailedplantmodel(pumpoperation,forexample).Thehu-manreliabilityanalysisincludedinthePRAmodelofrecordalready includeshumanreliabilityanalysisrequiredforinitiatingeventsother thanthedebrisevent(which,whenstrainersuccesscriteriaareex-ceededassumescoredamage).(c)IntheSTP2013LAR,thePRArequiredsomemodi"cationstoaccommodatetheseveralnewECCSstrainerandin-vesselfailure modes.RoverDcreates,inanewinitiatingeventfordebris failureandtheinitiatingeventfrequencyisdirectlyusedasthein-creaseinCDF(theCDF).Inthisway,theSTPPRAdoesnot requiremodi"cationsinceanyinformationneededcanbeobtained directlyfromtheSTPPRA.4.LOCAFrequency(a)Causalmodeling:Themostaccuratemodelingoffailurelikelihood(LossofCoolantAccident(LOCA))atanygivenlocationinthe RCSpressureboundarywouldtakeintoconsiderationfailuremecha-nismsbasedoncausalmodelingoftheunderlyingphenomenathereby producingprobabilitiesforeachlocation.Theoretically,suchvalues couldbeusedinsumstoestimatethe(preferentially)frequency(or likelihood)ofaLOCAofanyparticularsizeinaplant.TheSTP 2013LARusedaweightingschemethatattemptedtopreservethe NUREG1829frequenciesbutadditionallytakingintoaccountin-servicedatawherecrackswereobservedandsomeconsiderationof thetypeofservice.InRoverD,aboundingmethod,calledtop-down, wasadoptedthatavoidstheneedtoaccountforweightingbyrely-ingonthefactthatlocationswheredebrisamountsexceedtested levelshavebeenmitigated.Thatis,theproblematicorriskloca-tionshavebeenmitigatedandonlythenonrisklocationshavenot been.TheRoverDmethodologyignoresthemitigationimprovements andequallyweightstheNUREG1829exceedancefrequenciesforall locationstherebyboundinglocale(b)DEGBversuscontinuummodel:TheSTP2013LARestimatedbreaksofanysizethatcouldbesupportedbyagivenpipediameter.This requiresassumingacontinuumofbreaksizesuptothepipediameter andgivesthemostcompletepictureofpossiblebreaksthatcould beusedinarisk-basedapplication.TheNUREG1829elicitation reportcanbeinterpretedtoindicateonlyDoubleEndedGuillo-tineBreaks(DEGBs)canoccur.Wenoteherethatbothattribu-tionandfrequencymustbeconsideredinanyinterpretation.Inthe RoverDmethodology,thecontinuumbreakmodeliscomparedtothe DEGB-onlymodelofinterpretationanditautomaticallyincludesa (conservative)interpretationofattribution(sphericalZoneOfIn"u-ence(ZOI)foralllocations).(c)Aggregationmodels:NUREG1829includestwoaggregationmethodsforcombiningtheexpertelicitations-arithmeticmeanandgeomet-Tuesday1 stMarch,2016:19:32,Page20of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONricmean.BecausethePRAcommunitymostgenerallyadoptsthegeometricmeanaggregationanditrepresentsamorerealisticesti-mate,theSTP2013LARadoptedthegeometricmeanaggregation.

TheRoverDmethodologyprovidesestimatesofbothaggregations.(d)Sampling:AlltheelicitedexceedancefrequencyquantilesandmeansaggregatedinNUREG1829decreaserapidlywithsizeofbreak.As aconsequence,samplingmustbedoneverycarefullytoensurethe longtailsofthedistributionsarecaptured.ThiswasdoneinCASA GrandeasdescribedintheSTP2013LARusingstrati"edsampling techniquesandensuringthattheDEGBbreaksizewassampledin eachquanti"cation.TheRoverDmethodologyavoidstheneedtoper-formsampling,inthewayrequiredforMonteCarloquanti"cation, byassumingallbreaksizeslargerthanthesmallestbreaksizepro-ducingmoredebristhanwastestedatthelocationareassumedtobe failure.Thisisaconservativeestimatethatalsoavoidsthepossibility ofinadequatesamplingoflongtails.5.FibermassdistributionTheSTP2013LARestimates"bermassdistributionintheRCBpool,thereactorcore,andtheECCSstrainers.ThemethodusedintheSTP 2013LARperformsestimatesforthepumpcon"gurationsassumedand calculatesheadlossbasedoncollectionofparticulates("ber,paint,chem-icalprecipitates).TheRoverDmethodologyperformsasimilarcalculation however,insteadoflookingatallpossiblepumpingcon"gurations,RoverD looksatexpectedandextremecasestoensurethein-vesseleare notlimiting.HeadlosscomputationisnotdoneinRoverD.Instead,re-sultsoftestingonanSTPECCSstrainermoduleareused.Any"ne"ber loadingthatexceedsthetestedamountisassumedtoleadtocoredamage.6.DebrisgenerationandtransportTheSTP2013LARincludedtimingconsiderationsandmanydtbreaksizesandorientations.Forexample,itisreasonabletoconsiderthat paintoutsidetheZOIwouldeithernotfailatallorifitdoesfail,failin relativelylargepiecesoverlongperiodsoftime.RoverDonlyrequiresthat theamountsoffailedcoatingsassumedinthetestareappropriatelycon-servative(acceptedtoexceedamountsexpected)orareotherwisebounded.

Asaconsequence,nomodelingoffailuresizeortimingisrequiredinthe RoverDmethodology.Tuesday1 stMarch,2016:19:32,Page21of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONTable1.1:SummaryofrelevancyofquestionsandresponsesbasedonadoptingtheRoverDmethodology.Therelevancy(RoverDStatus)isindicatedalongwithacross-referencetothequestionQuestion)andtheresponse(Response).Thebasis(Basissum-mary)refersbacktotheimpactsofRoverDtoclassesofcharacteristicssummarized inthedescriptionsinSection1.2thatwouldchangetherelevancyofthequestionand responseStatusQuestionResponseBasissummaryRound1RAIs,APLAB,General,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande-General:Question1aSection1.2,Item1RemovedItem1bAPLAB,CASAGrande-General:Question1bRemovedItem1cAPLAB,CASAGrande-General:Question1cRound1RAIs,APLAB,PlantCon"guration,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande-PlantCon"guration:Question1aSection1.2,Item2aRemovedItem1bAPLAB,CASAGrande-PlantCon"guration:Question1bRemovedItem2aAPLAB,CASAGrande-PlantCon"guration:Question2aSection1.2,Item2aRemovedItem2bAPLAB,CASAGrande-PlantCon"guration:Question2bRemovedItem3aAPLAB,CASAGrande-PlantCon"guration:Question3aSection1.2,Item3aRemovedItem3bAPLAB,CASAGrande-PlantCon"guration:Question3bRemovedItem3cAPLAB,CASAGrande-PlantCon"guration:Question3cRound1RAIs,APLAB,LOCAFrequencies,Section1.3.1.1RemovedItem1aAPLAB,CASAGrande,LOCAFre-quencies:Question1Section1.2,Item4aRemovedItem1bAPLAB,CASAGrande,LOCAFre-quencies:Question1 RequiredItem2APLAB,CASAGrande-LOCAFrequencies:Question2Section1.2,Item4bRemovedItem3APLAB,CASAGrande,LOCAFre-quencies:Question3Section1.2,Item4dRemovedItem4APLAB,CASAGrande,LOCAFre-quencies:Question4Round1RAIs,APLAB,CASAGrandetoPRAInterface,Section1.3.1.1 RequiredItem1aAPLAB,CASAGrande,toPRAIn-terface-General:Question1aSection1.2,Item5 RequiredItem1bAPLAB,CASAGrande,toPRAIn-terface-General:Question1b RequiredItem2aAPLAB,CASAGrandetoPRAInterface-General:Question2aSection1.2,Item4dRemovedItem2bAPLAB,CASAGrandetoPRAInterface-General:Question2bSection1.2,Item6RemovedItem3APLAB,CASAGrande,toPRAIn-terface-General:Question3Section1.2,Item3cRemovedItem4aAPLAB,CASAGrande,toPRAIn-terface-General:Question4aSection1.2,Item3acontinuednextpage...Tuesday1 stMarch,2016:19:32,Page22of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem4bAPLAB,CASAGrande,toPRAIn-terface-General:Question4bRemovedItem4cAPLAB,CASAGrande,toPRAIn-terface-General:Question4cRemovedItem5APLAB,CASAGrande,toPRAIn-terface-General:Question5Section1.2,Item3aRemovedItem6aAPLAB,CASAGrande,toPRAIn-terface-General:Question6aSection1.2,Item4dRemovedItem6bAPLAB,CASAGrande,toPRAIn-terface-General:Question6bRemovedItem6cAPLAB,CASAGrande,toPRAIn-terface-General:Question6cRound1RAIs,APLAB,PRAModel,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-General:Question1Section1.2,Item3 RequiredItem2APLAB,STPPRAModel-Gen-eral:Question2 RequiredItem3APLAB,STPPRAModel-General:Question3Round1RAIs,APLAB,SuccessCriteria,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-SuccessCriteria:Question1Section1.2,Item2bRemovedItem2aAPLAB,STPPRAModel-SuccessCriteria:Question2aSection1.2,Item2cRemovedItem2bAPLAB,STPPRAModel-SuccessCriteria:Question2bSection1.2,Item3a RequiredItem2cAPLAB,STPPRAModel-SuccessCriteria:Question2cSection1.2,Item2aRemovedItem3aAPLAB,STPPRAModel-SuccessCriteria:Question3aSection1.2,Item3aRemovedItem3bAPLAB,STPPRAModel-SuccessCriteria:Question3b RequiredItem3cAPLAB,STPPRAModel-SuccessCriteria:Question3cSection1.2,Item3aRemovedItem3dAPLAB,STPPRAModel-SuccessCriteria:Question3dSection1.2,Item3Round1RAIs,APLAB,HumanReliabilityAnalysis,Section1.3.1.1RemovedItem2APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1Section1.2,Item3cRemovedItem2APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2RemovedItem3aAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3aRemovedItem3bAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3bRemovedItem3cAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question3cRemovedItem4aAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question4aRemovedItem4bAPLAB,STPPRAModel-HumanReliabilityAnalysis:Question4bRemovedItem5APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5continuednextpage...Tuesday1 stMarch,2016:19:32,Page23of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem6APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6Round1RAIs,APLAB,PRAScope,Section1.3.1.1 RequiredItem1APLAB,STPPRAModel-PRAScope:Question1Section1.2,Item3 RequiredItem2APLAB,STPPRAModel-PRAScope:Question2Round1RAIs,APLAB,ResultsInterpretation,Section1.3.1.1RemovedItem1aAPLAB,ResultsInterpretation-Quanti"cation:Question1aSection1.2,Item3aRemovedItem1bAPLAB,ResultsInterpretation-Quanti"cation:Question1bRemovedItem2APLAB,ResultsInterpretation-Quanti"cation:Question2Round1RAIs,APLAB,UncertaintyAnalysis,Section1.3.1.1 RequiredItem1aAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1aSection1.2,Item6 RequiredItem1bAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1bSection1.2,Item3 RequiredItem1cAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

1cSection1.2,Item3a RequiredItem2APLAB,ResultsInterpretation-UncertaintyAnalysis:Question2Section1.2,Item4c RequiredItem3APLAB,ResultsInterpretation-UncertaintyAnalysis:Question

3Section1.2,Item1RemovedItem4aAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4aSection1.2,Item4RemovedItem4bAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4bRemovedItem4cAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question 4cRemovedItem4dAPLAB,ResultsInterpretation-UncertaintyAnalysis:Question

4dRemovedItem5APLAB,ResultsInterpretation-UncertaintyAnalysis:Question

5RemovedItem6APLAB,ResultsInterpretation-UncertaintyAnalysis:Question 6Round1RAIs,ACRB RequiredItem1ARCB:Question1Doseconsequnces RequiredItem2ARCB:Question2 RequiredItem3ARCB:Question3Round1RAIs,EMCB RequiredItem1ECMB,Question1Strainermechanicalcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page24of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem2EMCB,Question2StrainermechanicalRound1RAIs,EPNBRemovedItem1ENPB,Question1Section1.2,Item4RemovedItem2ENPB,Question2RemovedItem3ENPB,Question3RemovedItem4ENPB,Question4RemovedItem5ENPB,Question5 RequiredItem6aENPB,Question6aLOCAfrequency/ISIprogram RequiredItem6bENPB,Question6bRound1RAIs,ESGB,ChemicalRemovedItem1aESGB,ChemicalQuestion 1aSection1.2,Item5RemovedItem1bESGB,ChemicalQuestion 1bRemovedItem1cESGB,ChemicalQuestion 1cRemovedItem1dESGB,ChemicalQuestion 1dRemovedItem2ESGB,ChemicalQuestion2RemovedItem3ESGB,ChemicalQuestion3RemovedItem4ESGB,ChemicalQuestion4RemovedItem5ESGB,ChemicalQuestion5RemovedItem6ESGB,ChemicalQuestion6RemovedItem7ESGB,ChemicalQuestion7RemovedItem8ESGB,ChemicalQuestion8RemovedItem9ESGB,ChemicalQuestion9RemovedItem10ESGB,ChemicalQuestion 10RemovedItem11aESGB,ChemicalQuestion 11a RequiredItem11bESGB,ChemicalQuestion 11bRemovedItem12ESGB,ChemicalQuestion 12Section1.2,Item1RemovedItem13aESGB,ChemicalQuestion 13aRemovedItem13bESGB,ChemicalQuestion 13bRemovedItem13cESGB,ChemicalQuestion 13c RequiredItem14aESGB,ChemicalQuestion 14aTestisrequiredtobebounding RequiredItem14bESGB,ChemicalQuestion 14b RequiredItem14cESGB,ChemicalQuestion 14cRemovedItem15ESGB,ChemicalQuestion15Section1.2,RoverDimpactsRemovedItem16ESGB,ChemicalQuestion 16RemovedItem17ESGB,ChemicalQuestion 17 RequiredItem18aESGB,ChemicalQuestion 18aUseofAlOOHsurrogatecontinuednextpage...Tuesday1 stMarch,2016:19:32,Page25of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem18bESGB,ChemicalQuestion 18bSection1.2,Item5RemovedItem18cESGB,ChemicalQuestion 18cRemovedItem19ESGB,ChemicalQuestion 19RemovedItem20ESGB,ChemicalQuestion 20 RequiredItem21ESGB,ChemicalQuestion 21Testingresults,SM RequiredItem22aESGB,ChemicalQuestion 22a RequiredItem22bESGB,ChemicalQuestion 22bRound1RAIs,ESGB,CoatingsRemovedItem1ESGB,Coatings:Question1Section1.2,Item6 RequiredItem2ESGB,Coatings:Question2Testingresults,SMRemovedItem3ESGB,Coatings:Question3Section1.2,Item6RemovedItem4ESGB,Coatings:Question4RemovedItem5ESGB,Coatings:Question5 RequiredItem6aESGB,Coatings:Question6a2008TestingassumedIOZZOIRemovedItem6bESGB,Coatings:Question6bSection1.2,Item6RemovedItem6cESGB,Coatings:Question6c RequiredItem7ESGB,Coatings:Question7CoatingsprogramdescriptionRound1RAIs,SCVB RequiredItem1aSCVB,Question:1aUFSARchanges,exemptions RequiredItem1bSCVB,Question:1b RequiredItem2aSCVB,Question:2a RequiredItem2bSCVB,Question:2b RequiredItem3aSCVB,Question:3a RequiredItem3bSCVB,Question:3b RequiredItem3cSCVB,Question:3c RequiredItem4aSCVB,Question:4a RequiredItem4bSCVB,Question:4b RequiredItem4cSCVB,Question:4c RequiredItem5SCVB,Question:5RoverDdoesnotchangethecontainmentanalysis(currentLBcalculationisused).

RequiredItem6SCVB,Question:6 RequiredItem7SCVB,Question:7 RequiredItem8SCVB,Question:8RELAP5screeningcases RequiredItem9aSCVB,Question:9aUFSARchanges,exemptions RequiredItem9bSCVB,Question:9bRound1RAIs,SNPB RequiredItem1aSNPB,Question:1a RequiredItem1bSNPB,Question:1b RequiredItem1cSNPB,Question:1c RequiredItem1dSNPB,Question:1dUsedbyNRCfortheirthermal-hydraulicreview RequiredItem1eSNPB,Question:1e RequiredItem1fSNPB,Question:1f RequiredItem1gSNPB,Question:1g RequiredItem1hSNPB,Question:1h RequiredItem1iSNPB,Question:1i RequiredItem1jSNPB,Question:1j RequiredItem1kSNPB,Question:1k RequiredItem1lSNPB,Question:1lcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page26of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem1mSNPB,Question:1m RequiredItem2aSNPB,Question:2a RequiredItem2bSNPB,Question:2b RequiredItem2cSNPB,Question:2c RequiredItem2dSNPB,Question:2d RequiredItem3SNPB,Question:3 RequiredItem4SNPB,Question4STPBAPLBcalculation RequiredItem5SNPB,Question:5Round1RAIs,SRXB RequiredItem1dSRXB,Question1NRCreviewofRELAP5documentation RequiredItem2eSRXB,Question2 RequiredItem3SRXB,Question3 RequiredItem4SRXB,Question4RemovedItem5aSRXB,Question5aLimitingvaluesused RequiredItem5bSRXB,Question5bSection1.2,Item6RemovedItem5cSRXB,Question5cTablenotusedRemovedItem6SRXB,Question6LBContainmentanalysis RequiredItem7aSRXB,Question7aSTPBAPLBcalculation RequiredItem7bSRXB,Question7b RequiredItem8SRXB,Question8Coreblockageislimitcase RequiredItem9SRXB,Question9StrainerpenetrationRound1RAIs,SSIB,DebrisCharacteristics RequiredItem1SSIB,ZOI:Question1 RequiredItem2SSIB,DebrisCharacteristics:Ques-tion2RemovedItem3SSIB,DebrisCharacteristics:Ques-tion3Round1RAIs,SSIB,Transport RequiredItem4SSIB,Transport:Question4DebristransportinCASAstillrequired RequiredItem5SSIB,Transport:Question5 RequiredItem6aSSIB,Transport:Question6a RequiredItem6bSSIB,Transport:Question6b RequiredItem6cSSIB,Transport:Question6c RequiredItem6dSSIB,Transport:Question6d RequiredItem6eSSIB,Transport:Question6e RequiredItem7aSSIB,Transport:Question7a RequiredItem7bSSIB,Transport:Question7b RequiredItem7cSSIB,Transport:Question7c RequiredItem7dSSIB,Transport:Question7d RequiredItem7eSSIB,Transport:Question7e RequiredItem7fSSIB,Transport:Question7f RequiredItem8aSSIB,Transport:Question8a RequiredItem8bSSIB,Transport:Question8bRemovedItem8cSSIB,Transport:Question8cCorrelationsarenotusedinRoverDRemovedItem8dSSIB,Transport:Question8d RequiredItem8eSSIB,Transport:Question8e RequiredItem9SSIB,Transport:Question9DebristransportcalculationsinCASAarestillrequired RequiredItem10SSIB,Transport:Question10RemovedItem11aSSIB,Transport:Question11aCorrelationsarenotusedinRoverDRemovedItem11bSSIB,Transport:Question11bRemovedItem11cSSIB,Transport:Question11cRemovedItem11dSSIB,Transport:Question11dRemovedItem11eSSIB,Transport:Question11eRemovedItem12SSIB,Transport:Question12continuednextpage...Tuesday1 stMarch,2016:19:32,Page27of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem13SSIB,Transport:Question13Round1RAIs,SSIB,HeadLossandChemicalBumpUpRemovedItem14SSIB,HeadLossandChemicalEf-fectsBumpUp:Question14RemovedItem15aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15aHeadlosscorrelationsarenotusedinRoverDRemovedItem15bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15bRemovedItem15cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15cRemovedItem15dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question15dRemovedItem16aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16aRemovedItem16bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16bRemovedItem16cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16cRemovedItem16dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question16dRemovedItem17aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17aRemovedItem17bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17bRemovedItem17cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17cRemovedItem17dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17dRemovedItem17eSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17eRemovedItem17fSSIB,HeadLossandChemicalEf-fectsBumpUp:Question17fRemovedItem18aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18aRemovedItem18bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18bRemovedItem18cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18cRemovedItem18dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18dRemovedItem18eSSIB,HeadLossandChemicalEf-fectsBumpUp:Question18eRemovedItem19SSIB,HeadLossandChemicalEf-fectsBumpUp:Question19RemovedItem20SSIB,HeadLossandChemicalEf-fectsBumpUp:Question20RemovedItem21aSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21aRemovedItem21bSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21bRemovedItem21cSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21cRemovedItem21dSSIB,HeadLossandChemicalEf-fectsBumpUp:Question21dcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page28of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem22SSIB,HeadLossandChemicalEf-fectsBumpUp:Question22RemovedItem23SSIB,HeadLossandChemicalEf-fectsBumpUp:Question23RemovedItem24SSIB,HeadLossandChemicalEf-fectsBumpUp:Question24RemovedItem25aSSIB,HeadLossandChemicalEf-fectsBump-up:Question25aRemovedItem25bSSIB,HeadLossandChemicalEf-fectsBump-up:Question25bRemovedItem26aSSIB,HeadLossandChemicalEf-fectsBump-up:Question26aRemovedItem26bSSIB,HeadLossandChemicalEf-fectsBump-up:Question26b RequiredItem26cSSIB,HeadLossandChemicalEf-fectsBump-up:Question26cStrainerloadingrelatedtoactualperformancecomparedtotestRemovedItem26dSSIB,HeadLossandChemicalEf-fectsBump-up:Question26dHeadlosscorrelationsarenotusedinRoverDRemovedItem26eSSIB,HeadLossandChemicalEf-fectsBump-up:Question26eRemovedItem26fSSIB,HeadLossandChemicalEf-fectsBump-up:Question26f RequiredItem27SSIB,HeadLossandChemicalEf-fectsBumpUp:Question27StrainerLBNPSHRemovedItem28SSIB,HeadLossandChemicalEf-fectsBumpUp:Question28HeadlosscorrelationsarenotusedinRoverDRound1RAIs,SSIB,NPSHandDegasi"cation RequiredItem29SSIB,NPSHandDegasi"cation:Question29StrainerLBNPSH RequiredItem30SSIB,NPSHandDegasi"cation:Question30 RequiredItem31SSIB,NPSHandDegasi"cation:Question31 RequiredItem32SSIB,NPSHandDegasi"cation:Question32 RequiredItem33SSIB,NPSHandDegasi"cation:Question33 RequiredItem34SSIB,NPSHandDegasi"cation:Question34Strainerpenetrationdependson"owrateRemovedItem35SSIB,NPSHandDegasi"cation:Question35RoverDusesthepipeinsidediame-terforDEGBfrequencyevaluation RequiredItem36SSIB,NPSHandDegasi"cation:Question36StrainerLBNPSHRound1RAIs,SSIB,In-VesselandBoricAcidPrecipitation RequiredItem37SSIB,In-VesselandBoricAcidPre-cipitation:Question37StrainerLBBAPcalculationRound1RAIs,SSIB,DebrisBypass RequiredItem38SSIB,NPSHandDegasi"cation:Question38 RequiredItem39(a)iiiSSIB,DebrisBypass:Question39aDebrisbypassisrequiredfordownstreamanalysisinRoverD.

RequiredItem39bSSIB,DebrisBypass:Question39b RequiredItem39cSSIB,DebrisBypass:Question39c RequiredItem39dSSIB,DebrisBypass:Question39d RequiredItem39eSSIB,DebrisBypass:Question39econtinuednextpage...Tuesday1 stMarch,2016:19:32,Page29of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem39fSSIB,DebrisBypass:Question39fRound1RAIs,SSIB,DefenseInDepthandMitigativeMeasures RequiredItem40SSIB,DefenseInDepthandMitiga-tiveMeasures:Question40DIDandSMrequiredbyRG1.174 RequiredItem41aSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41a RequiredItem41bSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41b RequiredItem41cSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41c RequiredItem41dSSIB,DefenseinDepthandMitiga-tiveMeasures:Question41d RequiredItem42SSIB,DefenseInDepthandMitiga-tiveMeasures:Question42Round1RAIs,STSB RequiredItem1STSB:Question1TSsubmittedaspartofLAR RequiredItem2STSB:Question2 RequiredItem3STSB:Question3Round2RAIs,APLAB,ProjectQualityAssurance RequiredItem1Question1:ProjectQualityAssur-anceAppropriatequalitycontrolsrequiredforlicenseactivities RequiredItem2Question2:ProjectQualityAssur-ance RequiredItem3Question3:ProjectQualityAssur-ance RequiredItem4Question4:ProjectQualityAssur-anceRound2RAIs,APLAB,TreatmentofUnanalyzedPlantConditionsRemovedItem1cQuestion1:TreatmentofUnana-lyzedPlantConditionsSection1.2,Item3Round2RAIs,APLAB,HumanReliabilityAnalysisRemovedItem7Question7:HumanReliability AnalysisBoundinganalysisforoperatorre-sponse(allriskcategoriesassume coredamage)Section1.2,Item3.Round2RAIs,APLAB,KeyAssumptions/KeySourcesofUncertaintyRemovedItem1gQuestion1:KeyAssumptions/KeySourcesofUncertaintySection1.2,Item1.Round2RAIs,APLAB,ValidityofAssumptiononPumpCon"gurationsRemovedItem1Question1:ValidityofAssumptiononPumpCon"gurationsSection1.2,Item2.Round2RAIs,Round2RAIs,APLAB,CASAGrandetoPRAInterfaceRemovedItem7Question7:CASAGrandetoPRAInterfaceThemethodologynowstrictlylooksforsmallestbreaksizebelowwhichtested"nesamountsarenotex-

ceeded.Round2RAIs,APLAB,FidelitybetweenRELAPSimulationsandCASAGrande RequiredItem1Question1:FidelitybetweenRELAPSimulationsandCASA

Grande(Partiallyrequired)Section1.2,Item4d.Round2RAIs,APLAB,State-of-KnowledgeCorrelationcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page30of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummaryRemovedItem1Question1:State-of-Knowledge CorrelationRoverDdoesnotcalculatefail-ureprobabilities.Instead,RoverD calculatescoredamagefrequenciescomefromdirectevaluationoftheNUREG1829quantilesandmeans.Round2RAIs,Round2RAIs,APLAB,SelectionofJohnsonParametersRemovedItem1Question1:SelectionofJohnsonPa-rametersRoverDevaluatescalculatescoredamagefrequenciesfromdirecteval-uationoftheNUREG1829quan-tilesandmeans.Round2RAIs,EMCB RequiredItem2Question2StrainermechanicalmustbemetforRoverD.Round2RAIs,ESGB,ChemicalRemovedItem23Question23:ChemicalRoverDdoesnotusecorrelationstoevaluatestrainerheadloss.RemovedItem24dQuestion24:ChemicalRemovedItem25dQuestion25:ChemicalRemovedItem26cQuestion26:ChemicalRemovedItem27Question27:ChemicalRemovedItem28[ML15091A440]Question28:Chem-icalRemovedItem29Question29:ChemicalRemovedItem30Question30:ChemicalRemovedItem31Question31:ChemicalRemovedItem32Question32:Chemical RequiredItem33Question33:ChemicalCouldhaveimpactontestedamountofparticulateandCRUDctson headloss(astested.)RemovedItem34Question34:ChemicalRoverDdoesnotusecorrelationstoevaluatestrainerheadloss.Round2RAIs,ESGB,CoatingsRemovedItem8Question8:CoatingsAllunquali"edcoatingswerein-cludedintheSTP2008strainertestusedbyRoverD.

RequiredItem9Question9:CoatingsTheSTP2008strainertestbasisneedstobeshownconsistentwithNRC-required

assumptions.

RequiredItem10Question10:CoatingsRound2RAIs,SCVB RequiredItem10cQuestion10UFSARchangesandexemptionrequestsarerequiredforRoverD.

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RequiredItem(a)ML15246A128,Question14(5)(a)continuednextpage...Tuesday1 stMarch,2016:19:32,Page31of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem(b)ML15246A128,Question14(5)(b)

RequiredItem15ML15246A128,Question15 RequiredItem(1)ML15246A128,Question16(1)

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RequiredItem17ML15246A128,Question17 RequiredItem(d)ML15246A128,Question18(a)(b)(c)(d)Round2RAIs,SNPB RequiredItem1Question6BAPmustbemetinRoverD RequiredItem2Question7 RequiredItem3Question8 RequiredItem4Question9RemovedItem5Question10RoverDdoesnotrelyonHLSOtim-ingRound2RAIs,SSIB RequiredItem43Question43RoverDusesdebrisgenerationandtransport to"ndcritical/non-criticalweldlocations RequiredItem44Question44 RequiredItem45Question45 RequiredItem46Question46RemovedItem47Question47HeadlosscorrelationsarenotusedinRoverD.ChemicalarefromtestingRemovedItem48Question48 RequiredItem49Question49RoverDrequiresstrainerperfor-mancecalculationRemovedItem50Question50RoverDdoesnotusecorrelationsforheadloss RequiredItem51Question51RoverDrequiresstrainerperformancecalculation RequiredItem52Question52RemovedItem53Question53RoverDdoesnotusedistributionsforperformancemodeling RequiredItem54Question54RoverDrequiresstrainerperfor-mancecalculation RequiredItem55Question55RoverDrequiresDIDdescription RequiredItem55aQuestion55aRoverDdoesnotusecorrelationsforheadloss RequiredItem56Question56RoverDrequiresstrainerpenetrationcalculation RequiredItem57aQuestion57(a)

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RequiredItem57fQuestion57(f)RemovedItem58Question58RoverD"berloadingonlyforbreaksizedetermination RequiredItem59Question59RoverDrequirestheCADmodelandCASAGrandefordebrisgenerationandtransport RequiredItem60Question60Latent"beranderoded"berarere-quiredforRoverDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page32of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION...continuedStatusQuestionResponseBasissummary RequiredItem61Question61RoverDrequirestheCADmodelandCASAGrandefordebrisgeneration andtransportRemovedItem62Question62RoverDdoesnotusecorrelationsforheadloss RequiredItem63Question63RoverDrequirestheCADmodelandCASAGrandefordebrisgeneration andtransportRemovedItem64Question64RoverDdoesnotusecorrelationsforheadlossRemovedItem65Question65 RequiredItem66Question66RoverDrequiresBAPcalculationRound2RAIs,STSB RequiredItem4Question4Applicationtoclarifyuseofriskin-formationTuesday1 stMarch,2016:19:32,Page33of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.3Round1RAIs1.3.1APLAProbabilisticRiskAssessmentLicensingBranch1.3.1.1CASAGRANDE

• General1.RegulatoryGuide(RG)1.174,Revision2,AnApproachforUsingProbabilisticRiskAssessmentinRisk-InformedDecisionsonPlant Speci"cChangestotheLicensingBasis,May2011(ADAMSAcces-sionNo.ML100910006),Section2.3.3,ProbabilisticRiskAssess-mentTechnicalAdequacy,statesthatthePRAmodelshouldbe technicallyadequatefortheapplication.Volume6.2containsalist ofinputvariablesanddescribeswhethereachvariablewasmodeled asapointestimateoradistributioninCASAGrande.Accordingto item5.d(page158of179),thedecisionastowhethertouseapoint estimateoradistributionwasbasedontheavailabilityofdataforun-certaintyanalysisandtheavailableconsensusonthevaluesassigned tospeci"cfactors(e.g.,forsomevalues,thereisahighlevelofcon-

"dencebyindustryandNRC).Pleasedescribetheprocessusedto assignpointestimatesordistributionsinmoredetail.Foreachinput parameter,pleaseprovide:(a)Thebasisforusingapointestimateoradistribution.RemovedResponse,Pg.224(b)Thesourceoftheparametervalue(e.g.,licensingbasiscalcula-tion).RemovedResponse,Pg.235(c)WhethertheparameterisbasedonanNRC-acceptedvalue(e.g.,asdocumentedinthesafetyevaluation(SE)forNEI-04-07,Pres-surizedWaterReactorSumpPerformanceEvaluationMethodol-ogy(PackageADAMSAccessionNo.ML043280641).RemovedResponse,Pg.235

• CASAGrande,PlantCon"guration1.RG1.200,Revision2,AnApproachforDeterminingtheTechnicalAdequacyofProbabilisticRiskAssessmentResultsforRisk-Informed Activities,Revision2(ADAMSAccessionNo.ML090410014),Sec-tion1.4,PRADevelopment,Maintenance,andUpgrade,statesthat plantinformationusedinthePRA(e.g.,expectedthermal-hydraulic plantresponsetodtstatesofequipment)shouldbeasrealis-ticaspossible.Thermal-hydraulicsimulationsdescribedinVolume 6.2showthatpooltemperatureisbyparameterssuchas loss-of-coolantaccident(LOCA)breaksize,componentcoolingwa-ter(CCW)temperature,andthestatusofcontainmentspray,resid-ualheatremoval(RHR),andcontainmentfancoolers.Thesimpli-

"edcurvesusedbyCASAGrande(Volume3,Figure2.2.13)assume nominalvaluesfortheseparametersandanintactcontainment (Volume6.2,page6)yetareassumedtobeboundingbasedonqual-itativeargumentsstatedbyVolume3,Assumption1k,page72.(a)Pleasestateifvaryingtheaforementioned(orother)parame-tersfromtheirnominalvaluesproducetime-temperaturecurvesTuesday1 stMarch,2016:19:32,Page34of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthatwouldyieldhigherconditionalprobabilitiesofsumporcoreblockageforanydurationoftimeduringtheevent.Pleaseinclude considerationofall15pumpstate-LOCAsizecombinations(i.e.,

"vepumpcases1,9,22,26,and43,andthreeLOCAcategories (S/M/L[small/medium/large])forbothscenarioswherecontain-mentisintactandnotintact.RemovedResponse,Pg.235(b)Pleaseprovideatechnicaljusti"cationforusingonlynominalvaluesorcalculatecoredamagefrequency(CDF),largeearly releasefrequency(LERF),delta-CDFanddelta-LERF usingtime-temperaturecurvesthatmaximizetheprob-abilityofsumpandcoreblockagefortheentireassumedduration oftheevent.RemovedResponse,Pg.2352.RG1.174,Section2.3.2,LevelofDetailRequiredtoSupportanApplication,statesthatthelevelofdetailofthePRAmodelmust bettomodeltheimpactoftheproposedchange.Section2.2.8 ofVolume3statesthatTable2.2.14safetyinjection(SI)"owrates arebasedonsimulationsusingnominaloperatingconditions(i.e.,

allemergencycorecoolingsystem(ECCS)trainsoperating,allfan coolersoperating,andnominalCCWheatexchangertemperatures).

Furthermore,Volume2,page38statesthattoevaluatethepotential forgenericsafetyissue(GSI)-191phenomena,thetotalpump"ow fromthesumpisthemostimportantconsideration.(a)Pleasestatewhethervaryingtheaforementioned(orother)op-eratingconditionsfromtheirnominalvaluescouldproduce"ow ratesorotherthermal-hydraulicconditionsthatwouldyieldhigher conditionalprobabilitiesofsumporcoreblockageforanydura-tionoftimeduringtheevent.Pleaseincludeconsiderationofall 15pumpstate-LOCAsizecombinations(i.e.,"vepumpcases1, 9,22,26,and43,andthreeLOCAcategories(S/M/L)forboth scenarioswherecontainmentisintactandnotintact.RemovedResponse,Pg.236(b)Pleaseprovideatechnicaljusti"cationforassumingonlynomi-naloperatingconditionsorcalculateCDF,LERF,and using"owratesorotherthermal-hydraulicconditions thatmaximizetheprobabilityofsumpandcoreblockageforthe entireassumeddurationoftheevent.RemovedResponse,Pg.2363.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume3(page71of248),Assumption2bprovidesaqualitative argumentforwhyacombinationofpumpsfailinginthesametrain isworsethanthesamesetofpumpsfailingindttrains.This qualitativeargumentincludesasetofexamplescapturedinVolume 3,Tables3.1,3.2,and3.3.(a)Pleasejustifythisassumptionandclarifyifanengineeringanal-ysiswasperformedinsupportofthisassumption.RemovedResponse,Pg.237(b)Pleasestateifthisassumptionalwaysincreasestheconditionalprobabilityofstrainerfailure(i.e.,isthisaconservativeassump-Tuesday1 stMarch,2016:19:32,Page35of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtion?).Inotherwords,pleaseexplainifthereareanycombina-tionsofpumpsfailinginseparatetrainsthatwouldproducean equalorhigherapproachvelocityandanequalorhigherdebris accumulationonanyonestrainerthanthesamecombinationof pumpsfailinginasingletrain.Ifso,pleasejustifyexcludingthem fromtheanalysis.RemovedResponse,Pg.238(c)Pleasestateifthisassumptionalwaysincreasestheconditionalprobabilityofin-vesseleAssumption2backnowledgesthat somecombinationsofpumpsfailinginseparatetrainsmaypro-duceanequalorhigheramountofdebrisaccumulationinthe corewhencomparedtothesamecombinationofpumpsfailing inasingletrain.Pleaseprovidealistofthesecombinationsand justifyexcludingthemfromtheanalysis.RemovedResponse,Pg.238

• CASAGrande,LOCAFrequencies1.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume3,Section5.3.1(page124 of248)states,inpart,that...therelativeweight[s]ofbreaksinvariousweldlocationsarebasedonspeci"cdegradationmechanismsforcategories ofwelds.Thesefrequenciesweredeterminedfromananal-ysisofOM[degradationmechanism]-dependentweldfailure ratesbasedonservicedata,aBayesmethodforuncertainty treatmentdevelopedinthe[ElectricPowerResearchInstitute (EPRI)]risk-informedin-serviceinspection(RI-ISI)program, andestimatesofconditionalprobabilityversusbreaksizeus-inginformationdevelopedinNUREG-1829[EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElic-itationProcess,April2008(Volumes1and2:ADAMSAc-cessionNos.ML082250436andML081060300)].(a)Althoughnotexplicitlyquanti"ed,factorsotherthanbreaksizewereconsideredbytheNUREG-1829panelistswhendevelop-ingLOCAfrequencies.Forexample,NUREG-1829,Section6.3.2, ImportantAgingMechanisms,describesthepanelistsconsid-erationoffactorssuchasthermalfatigue,"ow-acceleratedcorro-sion,inter-granularstresscorrosioncracking,andmechanicalfa-tigue.Pleasedescribehowthesefactorswereusedtoquantifythe breakfrequencyforvariouspipesizes.Foranyfactorsusedinthe STPpilotanalysisthatwerealreadyconsideredbytheNUREG-1829panelists,pleaseexplainwhytheproposedapproachdoes notamounttodoublecounting.RemovedResponse,Pg.114(b)TheNUREG-1829totalLOCAfrequenciesreferencedbytheSTPpilotapplicationincludecontributionsfrombothpipingand non-piping(e.g.,nozzles,componentbodies,pressurizerheatersleeves,manways,andcontrolroddrivemechanismpenetra-tions)weldfailures.AsshowninNUREG-1829,Figure7.7,theTuesday1 stMarch,2016:19:32,Page36of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcontributionfromnon-pipingLOCAscanbesigni"cantandex-ceedsthecontributionfrompipingLOCAsforseveralcategories.

TheapproachdescribedinVolume3,Section5.3,LOCAFre-quency,oftheSTPNOCsubmittaldistributesthetotalLOCA frequenciesontopipeweldsonly.Whilethispreservestheover-allinitiatingeventfrequency,itdoesnotexplicitlyconsiderthe debrisgeneration,transport,etc.ofLOCAscausedbythesecon-tributors.Pleaseexplainhowthedebris-relatedriskfromnon-pipingcontributorswasestimatedinthisstudy.Pleaseprovidea justi"cationforanynon-pipingcontributorsthatwereexcluded fromtheanalysis.Removed,clari"-cationrequestedResponse,Pg.1142.RG1.174,Section2.3.4,PlantRepresentation,statesthatPRAre-sultsshouldbederivedfromamodelthatrealisticallyrepresentstheriskassociatedwiththeplant.NUREG-1829statesthat,ingeneral, acompleteruptureofapipeismorelikelythanapartialrupture.

Itappears,however,thatSTPsmethodologyleadstotheopposite result(i.e.,aruptureofagivensizeismorelikelytobecausedbya partialruptureofalargepipethanacompleteruptureofasmaller pipe).Pleaseillustratetheresultsofyourmethodbycomparingthe frequencyofpartialversuscompletebreaksforasetofrepresenta-tivepipesizes.Pleasedescribewhetherthemethodologydescribedin theSTPpilotisconsistentwiththeassumptionofNUREG-1829or providejusti"cationforanalternateapproach.

RequiredResponse,Pg.1803.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume3,Section5.3describestheprocessusedtode"nenon-uniform samplebinsforeachweldcase.Althoughthissectiondescribesthe processusedtodeterminethenumberofbinsforagivenweld,the processusedtode"nethebinsizesisnotdiscussed.Pleaseprovidea descriptionofthisprocess.RemovedResponse,Pg.1154.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.Volume3describestheprocess usedtoassignbreakfrequenciestoweldsincontainmentandcites thefollowingtwodocumentslistedasReferences7and8:

-Reference7:KNFConsultingServicesLLCandScandpowerRiskManagementInc.DevelopmentofLOCAInitiatingEventFre-quenciesforSouthTexasProjectGSI-191FinalReportfor2011 WorkScope.September2011.

-Reference8:UniversityofTexasatAustin.ModelingandSam-plingLOCAFrequencyandBreakSizeforSTPGSI-191Resolu-tion.September2012.PleaseprovideReference7onthedocketandclarifyexactlywhichaspectsoftheaforementionedreferences(e.g.,byprovidingspeci"c sectionorequationnumbers)areusedintheSTPpilot.RemovedResponse,Pg.116

• CASAGrandetoPRAInterfaceTuesday1 stMarch,2016:19:32,Page37of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.Page3ofEnclosure1ofletterdatedNovember13,2013,states:Fail-uremodesleadingtocoredamageareexplicitlymodeled,excluding thosethatwerepreviouslyaddressedfortheplantusingdetermin-isticevaluations.Also,basedoninformationonpage20ofVolume 3CASAGrandedoesnotanalyzefailuremechanisms4and6(ex-vesseleandcrudonclad,respectively)becausetheyhaveal-readybeenaddresseddeterministically.Thisisinconsistentwiththe risk-informedapproachassetforthinRG1.174,Section1,Element 1:De"netheProposedChange,inthatthelicenseeshouldidentify thoseaspectsoftheplantslicensingbasis(LB)thatmaybe bytheproposedchange.(a)Pleaseprovideabasisforexcludingthetwofailuremechanisms(4and6)fromtheriskassessment.

RequiredResponse,Pg.116(b)PleaseidentifyotherfailuremechanismsorassumptionsrelatedtoGSI-191phenomenathatrelyondeterministicacceptancecri-teria(includingdeterministiccriteriaacceptabletotheNRC) thatwerenotincludedintheriskassessment.

RequiredResponse,Pg.1162.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

PRAmodelstypicallyclassifyLOCAbreaksizesaccordingtoscenario andcorrespondinginstructures,systems,and components(SSCs)availabletomitigatetheeventandcorrespond-ingsuccesscriteria.Fordeterminingtheofdebrisontheseven failuremechanismsde"nedinthesubmittal,adtsetofbreak sizesmightbemoreappropriate.Forexample,ifthereisaminimum sizeLOCAnecessarytoresultinfailureofrecirculationduetodebris, thenincludingLOCAsbelowthatsizewhendeterminingfailureprob-abilitiesmaymaskthetrueriskimpact.Pleaseprovidethefollowing

information:(a)Thelargestbreaksizebelowwhichnofailureswererecordeddur-ingtheCASAruns.Required(Dsmall i)Response,Pg.238(b)Inaddition,forthechosenLOCAsizes,pleasedescribescenariotimingdforthedebrismodelcomparedtothebase PRA,changesinsuccesscriteriaasaresultofdebris,andchanges inoperatorresponse.RemovedResponse,Pg.2383.RG1.174Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbettomodeltheimpactoftheproposedchange.Table 2.2.11(Volume3,page43of248)providesthefrequencyofsuccess pumpcombinationstates.Pleaseexplainwhatthistermmeans,how thefrequenciesinthecolumntitled,PumpStateFrequencywere derived,andhowtheywereusedintheanalysis(bothCASAGrande andthePRAmodels).RemovedResponse,Pg.1174.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Assumption4onpage6ofVolume 2states,inpart,thatTheCASAGrandemodelsassumecontainmentsystemsareTuesday1 stMarch,2016:19:32,Page38of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsuccessful(containmentpurgeisolation,isolationofsmallcontainmentpenetrations,thatatleasttwoofsixfancoolers operate,andthatCCWisavailabletotheRHRheatexchang-ers)forpurposesofevaluatingsumpfailureprobabilities.HighlevelrequirementLE-EofAmericanSocietyofMechanicalEn-gineers/AmericanNuclearSociety(ASME/ANS)RA-Sa2009(The ASMEPRAStandard)states:Thefrequencyoftcontain-mentfailuremodesleadingtoalargeearlyreleaseshallbequanti"ed andaggregated.Pleaseprovidethefollowinginformationforacci-dentscenarioswherethecontainmentisnotsuccessfullyisolatedor wheresomecontainmentsystemsdonotoperateasassumed:(a)Pleaseexplainwhethertheprobabilitiesofthevariousdebris-relatedfailuremechanismsaretforsuchscenarios.RemovedResponse,Pg.117(b)Pleaseexplainhowanyinthoseprobabilitiesareac-countedforinthePRAmodel.RemovedResponse,Pg.118(c)PleaseexplainhowtheaboveassumptionforCASAGrandemeetshighlevelrequirementLE-EofthePRAStandard.RemovedResponse,Pg.1185.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume2,page25states,inpart,thatEarlyonintheassessmentofGSI-191phenomenaitwasdeterminedthattheonlysequenceclassesrequiringsumpre-circulationthatwouldbectedaremediumLOCAs(2-6diameterbreaks)andlargeLOCAs(6diameterbreaks).Also,Volume1,page24states,inpart,thatNofailureswererecordedforsmall-ormedium-breakevents,andittranspiredthatonlythehigherrangeoflarge-break eventscontributedtofailure.Inadditiontothecomposite PRAfailuremodes,totalfailureprobabilityconditionedon theLOCAcategoryisprovided.PRAmodelsoftenincludehighandlowpressurerecirculationineventtreesforsmallLOCAs.Pleaseexplainhowitwasdeterminedthat onlymediumandlargeLOCAswouldrequiresumprecirculation.

Also,pleaseexplainwhytherewerenofailuresforsmallormedium LOCAs,includinganexplanationofthephysicalphenomenathat ledtothisresult.Pleaseincludeinthisexplanationastatementas towhetherthisresultwasduetotdebrisgenerationor Volume3,page81,Assumption11.RemovedResponse,Pg.1196.RG1.174Section2.2statesthatitisessentialtheuncertaintiesberecognizedwhenassessingwhethertheprinciplesofrisk-informed decision-makingaremet.Page84,Volume2states,inpart,thatThefailureprobabilitiesfor[TopEventSUMP]areprovideddirectlyfromCASAGRANDEoutputinVolume3.Theun-certaintyinthesefailureprobabilities[is]reportedasdiscrete probabilitydistributionswith5pointseach.Tuesday1 stMarch,2016:19:32,Page39of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONThisappearstocon"ictwithVolume3,Section6(page233),whichstatesthat15pointestimatesofconditionalfailureprobabilityare averagedforusebythePRA.(a)Pleaseexplainhowmanypointestimates(i.e.,distinctcondi-tionalfailureprobabilities)associatedwithasinglefrequencyvs.

breaksizecurve(e.g.,onecurvefrom"gure6.1inVolume3)were computedbyCASAGrande?RemovedResponse,Pg.119(b)WeretheseparameterspassedtothePRAasaprobabilitymassfunction,probabilitydensityfunction,orasasinglemeanvalue?RemovedResponse,Pg.119(c)PleaseexplainhowwerethesepointestimatesusedinthePRAparameteruncertaintyevaluation?RemovedResponse,Pg.120

• STPPRAMODEL1.RG1.200,Section2.2,IndustryPeerReviewProgram,statesthatwhentheNRCsregulatorypositionscontainedinitsappen-dicesaretakenintoaccount,useofapeerreviewcanbeusedto demonstratethatthePRAisadequatetosupportarisk-informed application.ItappearsthatthelatestpeerreviewoftheSTPPRA modelwasperformedtosupportSTPsapplicationforrisk-managed technicalspeci"cationsandtheresultsofthispeerreviewwerecap-turedbySTPinitsletterdatedFebruary28,2007(ADAMSAcces-sionNo.ML070670369).Pleasedescribeanysigni"cantchangesto theplantorPRAmodelthathavebeenmadesincethattime.Please stateifanyofthesechangesrepresentmodelupgradesasdiscussed intheASME/ANSPRAStandard.Pleaseprovidetheresultsofany focused-scopeorfullpeerreviewsconductedsinceletterdatedFebru-ary28,2007.Required(generalPRAquestion)Response,Pg.2402.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.Pleaseexplainthebasisofthe statementonpage11ofLAREnclosure3sincetheSTPNOCsPRA iscompliantwithRG1.200,Revision1forinternalevents,itiscom-pliantwithRG1.200,Revision2forassessingtheriskassociatedwith GSI-191.Pleaseexplainhowthisconclusionisreached.Required(generalPRAquestion)Response,Pg.1803.RG1.200,Section2.1,ConsensusPRAStandards,statesthatthecapabilitycategory(CC)neededforeachtechnicalrequirementis dependentonthespeci"capplication,althoughCC-IIisgenerally acceptable.Pleaseprovidealistofthesupportingrequirementsand correspondingCCsthatweredeterminedtobeapplicabletotherisk-informedresolutionofGSI-191.ForanycaseswherethenecessaryCC wasnotfoundtohavebeenmetbythepeerreviewprocess,please provideatechnicaljusti"cation.Required(generalPRAquestion)Response,Pg.240

• SuccessCriteria1.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume2,page7,item14,states:Tuesday1 stMarch,2016:19:32,Page40of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONOneoutofthreeeachfromHHSI[highheadsafetyinjec-tion]andLHSI[lowheadsafetyinjection]pumpsisassumed requiredformitigationofmediumLOCAs.Pleaseprovidethebasisforthisassumptionincludinghowdebrisonsuccesscriteriawereconsidered.

RequiredResponse,Pg.2412.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetech-nicallyadequatefortheapplication.ASME/ANSRa-Sa-2009SC-83

states:Whende"ningsuccesscriteria,USEthermal/hydraulic,struc-tural,orotheranalyses/evaluationsappropriatetotheevent beinganalyzed,andaccountingforalevelofdetailconsistent withtheinitiatingeventgrouping(HLR-IE-8)andaccident sequencemodeling(HLR-AS-AandHLR-AS-8).Volume3,Section5.10,In-VesselDownstream(page222),andVolume6.2,Item5.a.14describeaseriesofRELAP5simulations usedtoassesssmall,medium,andlargeLOCAsonboththehot-andcold-legsideofthereactorcoolantsystem(RCS)underfullcore blockageconditions.Accordingtothesesections,onlythemedium andlargecoldlegbreaksproceededtocoredamage...(a)Pleasediscusshowthesethermal-hydraulicanalysescontainedalevelofdetailconsistentwiththeinitiatingeventgroupingand accidentsequencemodeling.Inotherwords,explainwhetherthe breaksizesandlocationsassumedintheRELAP5simulations wereconsistentwiththoseusedinthePRAandelsewherein CASAGrande.RemovedResponse,Pg.242(b)PleaseexplainwhethertheplantconditionsassumedintheRE-LAP5simulations(e.g.,numberofavailableECCStrains)were consistentwitheachaccidentsequenceinwhichtheresultsfrom theRELAP5simulationswereused.Forexample,asequencein-volvingplantstate43(singleECCStrain)andamedium-break LOCAonthehot-legsidewouldappeartohaveassumedcondi-tionalprobabilityofcoreblockageduetoboronofzero.Please explainiftheRELAP5calculationshowingadequatecorecooling underthisscenarioaccountsforthemostlimitingmedium-break LOCA(breaksize/location)andifitisconsistentwithaccident sequencemodeling(i.e.,modelsonlyonetrainofECCS).There-sponseshouldaddressallGSI-191accidentsequencesthatused RELAP5simulations.RemovedResponse,Pg.242(c)RELAP5simulationsareusedtosupporttheconclusionthatadequatecorecoolingisachievedforsomeLOCAsevenunderthe assumptionofcompletecoreblockage.Pleasedescribehowthese simulationsaccountedforthereductionincladding-to-coolant heattransferthatwascalculatedbytheLOCADMcomputer code,asdescribedinVolume3,Section5.10.1.

RequiredResponse,Pg.2423.RG1.174,Section2.3.3statesthatthePRAmodelshouldbetechni-callyadequatefortheapplication.Volume3,Section4.2,StructuredTuesday1 stMarch,2016:19:32,Page41of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONInformationProcessFlow,describesthequanti"cationofnetposi-tivesuctionhead(NPSH)marginandcoreblockageasafunctionof time.Accordingtothissection,time-dependentvaluesarecompared againstacceptancecriteriafrom t=0(i.e.,timethattheLOCAoccurs)and t=30days.Thisappearstocon"ictwithVolume3,as-sumptionm,whichstatesthatitwasassumedthata36-hrruntime fortheCASAGrandesimulationsissttopredictthescenarios thatwouldproceedtofailure.(a)PleaseclarifytheaccidentdurationusedbyCASAGrandetocalculatetheconditionalprobabilityofsumpandcoreblockage.

Also,identifyallotheranalysesperformedoutsideofCASAGrande (e.g.,time-dependentcoatingsfailure)andtheirassumedacci-dentduration.RemovedResponse,Pg.243(b)ManyofthesimulationsperformedbyCASAGrandeconcludedthatnoneofthesevenperformancethresholdsidenti"edinVol-ume1,Section2.3.5,LOCAModels,wereexceeded.Forthese cases,pleasestateifananalysiswasperformedtocon"rmthat attheendofeachsimulation,theplantwasinasafe,stable endstate.Forexample,pleaseexplainifanycasesweretrending towardaperformancethresholdwhenthesimulationwaster-minated.Ifso,pleaseprovidejusti"cationthattheselectedacci-dentdurationwasappropriatetocaptureallphysicalphenomena (e.g.,long-termchemicalIffailuresduetoGSI-191phe-nomenacouldoccuraftertheCASAGrandeanalysisduration, pleaseexplainhowwasthiswasconsideredinthePRAmodel (noteSupportingRequirementSC-A5intheASME/ANSPRA

Standard).RemovedResponse,Pg.244(c)Pleasestatewhatplantconditionsandcon"gurationisassumedforthesafe,stableendstateinthePRAmodel.Pleasedescribe.

RequiredResponse,Pg.244(d)PleaseexplainwhethertheconditionalprobabilitiescalculatedbyCASAGrandewereadjustedinanywaytomatchthePRA missiontimeof24hours.RemovedResponse,Pg.245

• HumanReliabilityAnalysis1.RG1.174,Sections2.3.1,Scope,and2.3.2,LevelofDetailRe-quiredtoSupportanApplication,statethatthescopeandlevel ofdetailofthePRAmodelmustbesttomodeltheimpact oftheproposedchange.Assumption3.cinVolume3statesthat isolablebreakscanbeexcludedfromtheevaluationsinceisolable breakswouldnotleadtorecirculation.Pleaseexplainthebasisfor thisassumption.Pleasedescribewhathumanerrorprobabilitywas usedforthefailuretoisolateanisolablebreak.Pleasestatewhether thereareanyisolablebreaksthatcould,ifnotisolated,resultinthe needtoentertheECCSrecirculationmode.RemovedResponse,Pg.1202.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheTuesday1 stMarch,2016:19:32,Page42of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproposedchange.Undercertainconditions,operatoractionsrequiredtostartorsecurethepumpsmaydependontheofthedebris generatedbythespeci"cpipebreak.PleasedescribeifCASAGrande considersthepotentialforthenumberofrunningpumpstochange duringascenariobecauseofoperatoractionstakeninresponseto cuesthatdebrisisbuildinguponthesump.RemovedResponse,Pg.1213.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactofthe proposedchange.Volume2describestwotopeventsthatmodeloper-atoractionsusedtosecurecontainmentspray.TopeventOSI(page 77)representsashort-termactiontosecureonetrainofcontainment spraypriortorecirculation,giventhatallthreetrainsareavailable.

TopeventOFFS(page83)representsalonger-termactiontosecure alltrainsofcontainmentsprayoncecontainmentpressureandiodine levelsaresuitablylow,theseareconditionsthatmayoccurafterre-circulationisestablished.Accordingtotheirdescriptions,thesetop eventsarealwaysassumedsuccessfulwhendeterminingthefailure probabilitiesintroducedbytheGSI-191phenomena.Pleaseprovide thefollowinginformation:(a)PleasestateiftheCASAGrandemodelstheplantconditions(e.g.,sump"owrates,washdownrates,refuelingwaterstorage tank(RWST)drain-downtimes,etc.)thatwouldoccurifthree containmentspraytrainswererunning(i.e.,ifthemanualactions modeledbytopeventOSIareunsuccessful.)RemovedResponse,Pg.245(b)PleasestateiftheCASAGrandemodelstheplantconditions(e.g.,sump"owrates,washdownrates,RWSTdrain-downtimes, etc.)thatwouldoccuriftheoperatorsfailtosecurecontainment spraylongtermoncecontainmentpressureandiodinelevelsare suitablylow(i.e.,themanualactionsassociatedwithOFFSare

unsuccessful).RemovedResponse,Pg.245(c)Iftheanswertoeither(a)or(b)isno,pleaseprovideatechnicalbasisandexplainhowthePRAmeetstheASMEHLR-HR-G requirementtoperformanassessmentofpost-initiatorhuman failureeventsusingawell-de"nedandself-consistentprocessthat addressesscenario-speci"cin"uencesonhumanperformance.RemovedResponse,Pg.2464.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Volume2,page85statesthattheprobabilityofexcessboronprecip-itation(topeventBORON)dependsonthreefactors:(1)whether thebreakisinthecoldleg;(2)theextentofcore"owblockageprior tohot-legswitchover;and,(3)whetheralowheadsafetyinjection (LHSI)trainisrealignedforhot-legrecirculation.(a)PleaseprovidetheprobabilityassignedtoBORONforeachcom-binationofthesethreefactorsusedinthePRAmodel.Atable orgraphicmaybeausefulwaytoprovidethisinformation.RemovedResponse,Pg.121(b)Assumption1.jinVolume3(page72of248)statesthatswitchovertohotleginjection(factor3)isassumedtooccurbetween5.75Tuesday1 stMarch,2016:19:32,Page43of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONand6hoursafterthestartoftheevent.Pleasedescribehowthehumanerrorprobabilities(HEPs)associatedwiththistopevent (HLEG)weredevelopedandhowtheyaccountforLOCAsize andplantcon"guration(e.g.,numberofpumpsavailable,impact ofdebris,etc.),aswellasfactors1and2de"nedabove.RemovedResponse,Pg.1225.RG1.174,Section2.3.2statesthatthelevelofdetailofthePRAmodelmustbesttomodeltheimpactoftheproposedchange.

Onpage32ofVolume3,otherimportantlonger-termactionsare listed,whichinclude:(1)Securingonecontainmentspraypumpifall threecontainmentspraypumpsaresuccessfullyinitiated;(2)Secur-ingallcontainmentspraypumpslaterintheevent;(3)Switchover toECCSsumprecirculationaftertheRWST[refuelingwaterstorage tank]hasbeendrained;and(4)Switchovertohotleginjection.Please explainhowtheCASAGranderesultsweredevelopedtoaddressthe variouscombinationsofsuccessandfailureoftheseoperatoractions.

PleasealsoexplainhowtheconsistencybetweentheactualPRAsce-narioandtheGSI-191basiceventfailureprobabilitiesdevelopedin CASAGrandewasassured.RemovedResponse,Pg.1806.RG1.174,Section2.5.5,ComparisonwithAcceptanceGuidelines,statesthatcareshouldbetakentoensurethattherearenounquan-ti"eddetrimentalimpactstoproposedchanges,suchasanincrease inoperatorburden.SectionC.5.8,MitigationofInadequateReactor CoreFlow,ofAppendixCtoVolume1listsanumberofopera-toractionsassociatedwithdebris.Foroperatoractionsthatapplyin boththeGSI-191PRAbasecasemodelandtheGSI-191PRAdebris model,pleaseexplainhoweachoperatoractionsHEPwasmodi"ed asaresultofdebrisconsistentwithASMEHLR-HR-G,whichstates thatscenario-speci"cin"uencesonhumanperformanceshouldbead-

dressed.RemovedResponse,Pg.124

• PRAScope1.Aseismiceventmaypotentiallydislodgeandtransportinsulationtothecontainmentsump.AnysubsequentsequenceofeventsthatleadstorecirculationfromtheECCSsumpcouldbeadverselyimpacted bydebris.RG1.174,Section2.3.1statesthatthescopeofthePRA modelmustbesttomodeltheimpactoftheproposedchange.

Pleaseidentifysuchaccidentsequencesandestimatetheincreasein coredamageandlargeearlyreleasefrequenciesduetoaseismicevent asaresultofhavingdebrissourcesinthecontainment.

RequiredResponse,Pg.1252.Volume2(page47of257)states,inpart,that...amediumLOCAononeprimaryloopwouldbeassumed.tobeaccompaniedbymediumLOCAonallotherloops.The resultisthatseismicallyinducedmediumandlargeLOCAs aremodeledasbeingexcessiveLOCAs-whichhavenosuccess sequencesbyde"nition.Tuesday1 stMarch,2016:19:32,Page44of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpactof theproposedchange.Whileitisacommonassumptionthatseismic failuresamonglikecomponentsare100percentcorrelated,forthis analysisthisassumptionleadstoalowercalculatedvalueofdelta risk.Thatis,forcaseswhereasinglelargepipefailsduetoaseismic initiatingevent,orwheremultiplesmallborepipesfail,itmightbe possibletomitigatethescenariotoagreaterextentifdebrissources donotexistinsidecontainment.Pleasejustifynotanalyzingtheaddi-tionalriskofGSI-191phenomenaforseismiceventswithoutreliance ontheconservativeassumptionof100percentcorrelation.

RequiredResponse,Pg.2461.3.1.2RESULTSINTERPRETATION

• Quanti"cation1.Volume2,page3states,inpart,thatThechangeincoredamagefrequencyandlargeearlyreleasefrequencyisdeterminedbycomparingtheresultsoftwomod-els:onewithnosourcematerialinthecontainmentcapable ofproducinganyGSI-191ctsandonerepresentingthe currentplantconditionsthatincludesboth"brousinsulation thatmightbeliberatedfollowingaLOCAandlatentmaterial foundinthecontainment.Also,elsewhereinthesubmittal,itsaysfailurebranchesarenotincludedsincetheyleadtocoredamagewithorwithoutdebris.This wouldimplythattheanalysisproducedthedeltariskdirectlyby consideringsuccessbranchesthatwouldbeimpactedbydebris, withouttheneedtosubtractabase-caserisk.Itisimportantthat theNRCunderstandhowtheriskwascalculated.RG1.174 Section2.2statesthatthelicenseeshouldassesstheexpectedchange inCDFandLERF.Pleaseprovidethefollowing:(a)PleaseclarifywhethertheCDFandLERFwerecalculatedbysummingonlytheformersuccessstatesthatgotocoredamage duetoGSI-191phenomenaorbyrequantifyingtheentiredebris modelandsubtractingthebasecase.RemovedResponse,Pg.126(b)PleaseexplainifthesameLOCAinitiatingeventfrequenciesandparameteruncertaintydistributionswereusedforboththebase-lineanddebrismodels.RemovedResponse,Pg.1262.Pleaseprovidealistofthetop100accidentsequencesthatresultincoredamageduetooneofthesevenfailuremechanismsidenti-

"edinVolume1;thatis,includeonlysequencesthatincludefailure ofrecirculationcoredamageresultingfromasaresultofGSI-191

phenomena.RemovedResponse,Pg.126

• UncertaintyAnalysisTuesday1 stMarch,2016:19:32,Page45of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.RG1.200de"nesmodeluncertaintyasanissuewherenoconsensusapproachormodelexistsandwherethechoiceofapproachormodelis knowntohaveanonthePRA(e.g.,introductionofanewbasic event,changestobasiceventprobabilities,changesinsuccesscrite-ria,introductionofanewinitiatingevent.).Volume1Section2.5.3, ModelUncertainty,containsageneraldiscussionofmodeluncer-tainty(usingchemicalanddebris"ltrationasexamples)and broadlystatesthatconservatismwasusedtoaddressmodeluncer-tainty.ThisisinconsistentwithRG1.200,Section3.3.2,Assessment ofAssumptionsandApproximations(andASMEHLR-QU-E)guid-ancethatstatesthatallsourcesofmodeluncertaintyshouldbeiden-ti"edandtheironthePRA(asidenti"edabove)shouldbede-terminedasdiscussedinRG1.174,Section2.5.5.Uncertaintymustbe evaluatedforthisanalysis,includingthePRAmodel,CASAGrande, andanysupportinganalyses.Pleaseprovidethefollowinginforma-

tion:(a)Pleaseidentifyallsourcesofkeymodeluncertaintyasde"nedbyRG1.200.RequiredResponse,Pg.246(b)Pleaseidentifythekeyassumptionsasde"nedbyRG1.200.

RequiredResponse,Pg.246(c)Pleasedescribethepotentialofthekeyassumptionsontheresultsofthisstudy;thatis,ontheCDFandLERFattributable toGSI-191phenomena.Describetheresultsofanyrelatedsen-sitivityanalysesthatwereperformed.

RequiredResponse,Pg.2472.Volume3,Assumption3.a(page76of248)statesthatthegeometric-meanaggregationofLOCAfrequenciesinNUREG-1829isthemost appropriatesetofresultstouseforthisevaluation.Thebasispro-videdisthatgeometric-meanaggregationproducesfrequencyesti-matesthatareapproximatelythesameasthemedianestimatesof thepanelists.Thereisnojusti"cationaboutwhythemedianesti-mateispreferredandemphasisonthemediancon"ictswiththeRG 1.174guidancethatthemeanvaluesbeusedfordecision-making.Fur-thermore,informationinNUREG-1829,Section7.6.4,Aggregation, showsthattheuseofthearithmeticmeaninsteadofthegeometric meanwouldincreasetheLOCAfrequencybyanorderofmagnitude ormoreforsomeLOCAcategoriesandmaythereforesubstantially increasetheriskestimates.Consequently,selectionofthegeometric meanisakeyassumptionandselectionofthearithmeticmeanrep-resentsanalternativereasonableassumptionasde"nedbyRG1.200.

ThisissupportedbyRG1.174,Section2.5,ComparisonofProb-abilisticRiskAssessmentResultswiththeAcceptanceGuidelines, whichstates,inpart,thatthelicenseeshould[identify]keyassump-tionsinthePRAthatimpacttheapplication.Sensitivitystudies provideimportantinformationabouthowsomeofthekeyassump-tionsthe"nalresultsasdiscussedinRG1.174Section2.5.3.

PleaseprovideCDF,LERF,andusingthearith-meticmeanaggregationofLOCAfrequenciesinNUREG-1829.

RequiredResponse,Pg.1563.Volume1,Section1.3.1,LOCAFrequency,statesthatLOCAfre-Tuesday1 stMarch,2016:19:32,Page46of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONquencieswereobtainedfromTable7.19ofNUREG-1829for25yearsoperation.Furthermore,assumption3.binVolume3(page76)states thatcurrent-dayLOCAfrequenciesaremoreappropriatetousefor thisevaluationthantheend-of-plant-licensefrequencies.RG1.174, Section2.5.5statesthatitisincumbentonthelicenseetodemonstrate thatthechoiceofreasonablealternativehypotheses,adjustmentfac-tors,ormodelingapproximationsormethodstothoseadoptedinthe PRAmodelwouldnotsigni"cantlychangetheassessment.Also,itis assumedthattheSTPplantswillcontinuetooperateformorethan 25years;RG1.174Section3,Element3:De"neImplementationand MonitoringProgram,statesthatthelicenseeshouldde"neanim-plementationandmonitoringprogramtoensurethatnounexpected adversesafetydegradationoccursdotothechange.Pleasejustify theuseofthe25-yearfrequencyestimatesratherthanthe40-year estimatesprovidedbyNUREG-1829.PleaseprovideCDF,LERF, andusingthe40-yearestimates.

RequiredResponse,Pg.2474.TheacceptanceguidelinesofRG1.174,Section2.5.5arede"nedsuchthattheappropriatemeasureforcomparisonisthemeanvalue oftheuncertaintydistributiononthecorrespondingmetric.Typi-cally,statisticalsamplingsimulationswilldeveloprandomvariables thatpreservethemeanofthedistributionfromwhichthevariables aresampled.STPhaschosento"taJohnsonboundeddistribution thatmatchestheexpert-provided5th,50th,and95thpercentilesin NUREG-1829,butdoesnotmatchthemeanvalues.Theproperties ofthedistributionaresuchthat,as"t,themeanofthe"tteddistri-butionisalwayslessthantheexpertsmeansfromthedistributions inNUREG-1829.(a)PleaseexplainwhytheSTPevaluationdepartsfromtheregula-torypositioninRG1.174regardingtheuseofmeanvalues.RemovedResponse,Pg.248(b)TheJohnson"tto5th,50th,and95thpercentilesisnotunique.Alternativeaccurate"tscanbeconstructedwitharbitraryval-uesofthescaleparameterA.ThescaleparameterAde"nesa boundonthemaximalfrequenciessampledintheMonteCarlo model.ByincreasingthevalueofA,therelativeproportionof largetomediumtosmallbreakscanbealtered,especiallyinthe extrapolationrangebeyondthe95thpercentile.Pleaseprovidea technicaljusti"cationfortheselectionofthescaleparameterA (otherselectionsappearpossiblethatcouldchangetheoutputs byCASAGrande).RemovedResponse,Pg.248(c)PleaseprovidethemaximumexpectedbetweentheCDF,LERF,anddevelopedfromboundedJohn-sondistributionsthatconsideralternativevaluesofthescalepa-rameterA,andotherdistributionsthatwouldpreservemeanval-uesreportedinNUREG-1829.Note,inparticular,thatalterna-tiveboundedJohnsondistributionswithlargevaluesofthescale parameterAcanbebuilttoaccurately"ttheNUREG-18295th, 50th,and95thpercentiles,andproducemeanestimatesclosertoTuesday1 stMarch,2016:19:32,Page47of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtheNUREG-1829valuesthancurrent"tsusedbySTP.RemovedResponse,Pg.249(d)InTable8.4-1inVolume2,LOCAexceedancefrequenciesaretabulatedfortbreaksizesthatareconsistentwithmod-i"edboundedJohnsondistributions(themodi"edJohnsonisa scaledboundedJohnsonplusauniformdistribution)designedto matchNUREG-1829meanvalues.The"ttothe5th,50th,and95thNUREG-1829percentilesofthesemodi"edJohnsondistri-butionsdoesnotappeartobeaccurate.Therefore,thesemod-i"edJohnsondistributionsinferredfromTable8.4-1appearto betthantheboundedJohnsondistributionssummarized inTable2.2.2inVolume4d.Pleasejustifytheapparentuseof tboundedJohnsondistributionsinthePRAandCASA

Grande.RemovedResponse,Pg.2495.Volume2,page6states,inpart,thattheLOCAfrequencyuncer-taintiessampledinthePRAuncertaintyanalysisareassumedinde-pendentoftheprobabilitiesoffailurefromtheuncertaintyanalysis ofCASGrande.Thisassumptiondoesnotaccountforthestateof knowledgecorrelationbecausethePRAandCASAGranderelyon thesameparameterfortheirquanti"cation(LOCAfrequencyde-rivedfromNUREG-1829).RG1.174,Section2.5.2,ParameterUn-certainty,statesthatthestateofknowledgecorrelationshouldbeac-countedforunlessitcanbeshowntobeunimportant.Therefore,you arerequestedtoeithercalculateCDF,LERF,and accountingforthestate-of-knowledgecorrelationordemonstratethat itisunimportanttothisapplication.RemovedResponse,Pg.2496.RG1.174Section2.5.5statesthatitisincumbentonthelicenseetodemonstratethatthechoiceofreasonablealternativehypotheses, adjustmentfactors,ormodelingapproximationsormethodstothose adoptedinthePRAmodelwouldnotsigni"cantlychangetheas-sessment.Thisdemonstrationcantaketheformofwell-formulated sensitivitystudiesorqualitativearguments.Ingeneral,theresultsof thesensitivitystudiesshouldcon"rmthattheriskacceptanceguide-linesarestillmetevenunderalternativeassumptions.Pleaseprovidetheresultsofanaggregateanalysisthatquanti"estheintegratedimpactonCDF,LERF,andfromall sensitivitystudiesthatwereperformed.Inthisaggregateanalysis, forthosecaseswhereindividualassumptionshaveasynergisticef-fectontheresults,asimultaneousanalysisshouldbeperformed.For thosecaseswherenosynergyexists,aone-at-a-timeanalysismaybe t.RemovedResponse,Pg.2491.3.2ARCB:RadiationProtection&ConsequenceBranch1.Inantoensureacompleteandaccuratereviewofthedosecon-sequenceanalyses,pleaseprovideadditionalinformationintabularform describing,foreachdesignbasisaccidentbytheproposedRisk InformedGSI-191submittal,allthebasicparametersusedinthedoseTuesday1 stMarch,2016:19:32,Page48of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONconsequenceanalyses.Foreachparameter,pleaseindicatethecurrentli-censingbasis(CLB)value,therevisedGSI-191valuewhereapplicable,as wellasthebasisforanychangestotheCLB.Anexampleoftheinput/as-sumptionsneededisprovidedinTable4.3-11DoseAnalysisInputsfor LOCAprovidedinSTPsalternatesourceterm(AST)submittaldated March22,2007(ADAMSAccessionNo.ML070890474).TheNRC requeststhattheinformationincludeallofthebasicparameterswhether ornottheindividualparameterisbeingchangedfortheGSI-191amend-ment.TheNRCalsorequeststhattheinformationbepresentedin separatetablesforeachaccident(i.e.,LOCA,thefuelhanding accident(FHA),themainsteamlinebreakaccident(MSLB),thesteam generatortuberuptureaccident(SGTR),thecontrolrodejectionaccident (CREA),andthelockedrotoraccident(LRA)).

RequiredResponse,Pg.2512.STPidenti"edthefollowingconditionrelatedtotheASTsubmittal:WestinghouseElectricCompanyNuclearSafetyAdvisoryLetter(NSAL)-06-15,datedDecember13,2006,advisedoperatorsofWestinghouseplants thatthesingle-failurescenariofortheSGTRanalysisthatlicenseesused intheiraccidentanalysismaynotbelimiting.AsstatedintheSTP ASTNRCSafetyEvaluationdatedMarch6,2008(ADAMSAccessionNo.

ML080160013),ThelicenseehasevaluatedtheapplicabilityofNSAL 15againsttheaccidentanalysisassumptionsandhasdeterminedthatthe currentsingle-failureassumptionfortheSTPSGTRanalysisisnotlim-iting.Therefore,thelicenseeisoperatingundercompensatorymeasures tomeetregulatorydoseguidelines.Thelicenseeplanstoresolvethiscon-ditionattheearliestopportunitysothattheassumptions,includingthe limitingsinglefailure,fortheSGTRaccidentanalysisdescribedhereinare consistentwiththeplantresponsetothisevent.Tosupportthelimiting single-failureassumptionsintheSGTRanalysis,STPwillmaintainan administrativelimitforreactorcoolantsystem(RCS)doseequivalentio-dine131(DEI)sothattheradiologicaldosereferencevaluesfortheSGTR analysisremainbounding,andthelicenseewillcontinuetocomplywith GOG[GeneralDesignCriteria]19.Pleasestateifthisconditionbeenresolved?Ifso,pleasedescribehow?Also,pleaseprovidejusti"cationthatGOG19continuestobemet.

RequiredResponse,Pg.2513.TheLOCAanalysisassumesthatiodinewillberemovedfromthecontain-mentatmospherebycontainmentsprayandnaturaltothecon-tainmentwalls.Asaresultoftheseremovalmechanismsalargefractionof thereleasedactivitywillbedepositedinthecontainmentsump.Thesump waterwillretainsolublegasesandsoluble"ssionproductssuchasiodines andcesium,butnotnoblegases.TheguidancefromRG1.183,Alternate RadiologicalSourceTermsforEvaluatingDesignBasisAccidentsatNu-clearPowerReactors,July2000(ADAMSAccessionNo.ML003716792),

speci"esthattheiodinedepositedinthesumpwatercanbeassumedto remaininsolutionaslongasthecontainmentsumppHismaintainedat orabove7.TheASTapplicationindicates:Tuesday1 stMarch,2016:19:32,Page49of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONAfterthe"rstday,thecontainmentsumppHwillbegintodecrease,reach-ing6.8bytheendofthe30-daydurationoftheradiologicalconsequence analysisfortheDesignBasisAccident(DBA)LOCA,andtheimpactof thatdecreasehasbeenre"ectedintheControlRoomanddoses.ItisnotedthattheASTapplicationfurtherindicates:ThedesigninputsforcalculatingthecontainmentsumppoolpHwereconservativelyestab-lishedbythelicenseetomaximizetheacidiccontributiontosumppHand minimizethebasiccontribution.TheGSI-191applicationindicatesthepossibilitythatdebrisgeneratedduringaLOCAcouldclogthecontainmentsumpstrainersinpressurized-waterreactors(PWRs)andresultinlossofNPSHfortheEGGSandCSS

[containmentspraysystem]pumps,impedingthe"owofwaterfromthe

sump.Pleasediscusstheexemptionjusti"cationastheyrelatetotheeonsumpwaterpH,radiologicalconsequences,andlossofthecontainment spraysystem(CSS).

RequiredResponse,Pg.2511.3.3EMCB:MechanicalandCivilEngineeringBranch1.Intheapplication,thelicenseeprovidedaqualitativeresponseregardingthestructuralanalysiswithoutanysupportingquantitativedata.Without actualandallowablestressesanddesignmarginsforthevariouscompo-nentsofthesumpstrainerstructuralassembly,theNRCisunableto makeadeterminationabouttheinherentlevelofconservatismemployedin thedesign.Thisinformationwasnotprovidedinthelicenseesrecentsub-mittalsconcerningGenericLetter(GL)2004-02,PotentialImpactofDe-brisBlockageonEmergencyRecirculationduringDesignBasisAccidents atPressurized-WaterReactors,(ADAMSAccessionNo.ML042360586).Pleasesummarizethestructuralquali"cationresults,includingtheactualandallowablestresses,anddesignmarginsforthevariouscomponentsof thesumpstrainerstructuralassembly.

RequiredResponse,Pg.251 2.ResponsetoEMCBFollow-upRAIdatedJune2,2014ByletterdatedDe-cember23,2013(AgencywideDocumentsAccessandmanagementSystem (ADAMS)AccessionNo.ML14015A312,STPNuclearOperatingCom-pany(STPNOC)providedresponsetotheU.S.NuclearRegulatoryCom-mission(NRC)questionSTP-GSI-191-EMCBRAI-1.Inresponsetothe NRCquestion,STPNOCprovidedinteractionratios(IRs)forvari-ouscomponentsofthestrainerassemblyfortwoloadcases.AlloftheIRs werebelowone,indicatingallapplicabledesigncoderequirementswere satis"ed,bymaintainingactualstressesandloadslessthantheallowable values.However,itisuncleartotheNRCwhattialpressures theanalyzedloadcasesrepresentandhowtheyrelatetothe5.71feet(ft.)

and9.35ft.ofequivalentheadlossdiscussedinsubmittaldatedNovember 13,2013((ADAMSAccessionNo.ML13323A183).Inaddition,therisk-informedsubmittalnotedthatstrainerstructuralfailurewasapossible failuremode.Thisappearstoindicatethatthereareloadingconditions wheretheIRvalueswouldbegreaterthan1andthestrainercouldfail.Tuesday1 stMarch,2016:19:32,Page50of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONHowever,Section6.2.2.2.3ofAttachment2toEnclosure3ofsubmittaldatedNovember13,2013states,Thesumpstructuresaredesignedto withstandthemaximumexpectedtialpressureimposedbytheac-cumulationofdebris.PleaseidentifythetialpressureorequivalentheadlossassociatedwiththetwoloadcasesprovidedinletterdatedDecember23,2013,in responsetotheRAIquestion.Pleaseexplainifthereareconditionswhich couldloadthestrainersbeyondthemaximumtialpressurefor whichtheyarequali"ed.RevisetheabovestatementfromSection6.2.2.2.3, asnecessary,basedonyourresponse.

RequiredResponse,Pg.2521.3.4EPNB:ComponentPerformance,NDEandTestingBranchTheNRChasreviewedtheLOCAfrequencyestimatesinSections2.2.3,LOCAFrequencies,and5.3,LOCAFrequency,ofVolume3andrequests thefollowingadditionalinformation.1.Volume3,Section5.3.1,RelativeWeightofBreaksinSpeci"cWeldCat-egories,page125,speci"esthedegradationmechanismsthatwereconsid-eredintheLOCAfrequencyestimates.Therisk-informedinserviceinspec-tion(RI-ISI)programatSTPwasbasedonEPRITR-112657,Revised Risk-InformedlnserviceInspectionEvaluationProcedure(PWRMRP-05),"

RevisionB-A,FinalReport,December1999(ADAMSAccessionNo.ML013470102).TheNRCnotesadiscrepancyinthedegradationmecha-nismsusedbetweentheRI-ISIprogramandtheGSI-191submittal.Several ofthedegradationmechanismsinTable2-2ofEPRITR-112657report thatareusedintheRI-ISIprogramarenotlistedasthedegradation mechanismsintheGSI-191calculations.Forexample,erosioncavitation, corrosionfatigue,corrosionattack,andwaterhammeridenti"edinTable 2-2oftheEPRIreportarenotconsideredinSection5.3.1.Pleasediscuss thediscrepancy.RemovedResponse,Pg.2522.Volume3,Section5.3.1,page125,statesthatTable5.3.1,Category68,containstwoweldsizes(nominal0.75-inchand1-inchpipes).However, Table2.2.6,Category68showsonly1-inchweldsize.Pleasediscusshow theLOCAfrequencycalculationshandlethisdiscrepancy.Thatis,please discusswhethertheinitiatingfrequencycalculationincludesthefrequen-ciesfromthe0.75-inchand1-inchpipesizesoronlythe1-inchpipesize isused.ThisdiscrepancyalsoappliestoCategories6Aand8Cwhichalso containtwoweldsizes.RemovedResponse,Pg.2533.PleasediscusswhetherweldsevaluatedintheGSI-191analysiscontain"awswhileinservice.Ifyes,pleasediscusswhethertheLOCAfrequencies fortheseweldsareincreasedfromthatofNUREG-1829estimates.Ifthe pipefailureprobabilitiesfortheseweldsarenotincreased,pleaseprovide justi"cations.Volume3,Table5.3.1,page126showsthatfourweldsat thepressurizerwereweldoverlaid.Pleasediscusswhetherthepipefailure probabilityLOCAfrequenciesforthesemitigatedweldswerereducedfrom thefrequencyestimatesofNUREG-1829.Ifnot,pleaseprovidejusti"ca-

tions.RemovedResponse,Pg.253Tuesday1 stMarch,2016:19:32,Page51of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION4.Title10oftheCodeofFederalRegulations(10CFR),Part50,50.55a(g)(6)(ii)(F)incorporatesbyreferenceAmericanSocietyofMechanicalEngineersBoiler andPressureVesselCode(ASMECode)CaseN-770-1,AlternativeEx-aminationRequirementsandAcceptanceStandardsforClass1PWRPip-ingandVesselNozzleButtWeldsFabricatedwithUNSN06082orUNS W86182WeldFillerMaterialWithorWithoutApplicationofListedMit-igationActivities,SectionXI,Division1,withconditions.ASMECode CaseN-770-1requireslicenseestoperformaugmentedinspectionsbeyond thosethatarerequiredbytheASMECode,SectionXI,forpipingwith Alloy82/182dissimilarbuttwelds.Pleasediscusswhetherperiodicinspec-tionsperASMECodeCaseN-770-1wouldreducetheLOCAfrequency estimationfortheAlloy82/182dissimilarmetalwelds.Ifyes,pleasedis-cusshowmuchLOCAfrequencyestimateswerereducedforthesewelds.RemovedResponse,Pg.2545.Volume3,Section5.3.5,SampleBreakSizesatEachWeldLocation,page149,discusseshowthebreaksizesareselectedtoderivetheLOCA frequencyestimates.Figure5.3.4,page151,providestheselectedbreak sizesforweldcase1Basanexample.(a)Figure5.3.4presentsatotal of13breaksbeingsimulatedateachweldbelongingtoWeldCase1B (10largebreaks,twomediumbreaksandonesmallbreak).However,in Table2.2.3,underweldcase1B,theNRC"ndsonly12breaks.Please explainhow13breakswereidenti"ed.(b)Pleasediscusshowthebreaksize distributionschemeinFigure5.3.4providescon"denceandassurancethat thebreakselectionwillresultinappropriatedebrisgenerationasthereare manypossiblescenariosforthebreaksizedistribution.Thebreaksizes couldbeevenlydistributedsuchthattherearefoursmallbreaks,four mediumbreaksandfourlargebreaks(assumingthetotalbreaksare12).

Thebreaksizescouldbedistributedskewedtothesmallsize,suchas10 smallbreaks,onemediumbreakandonelargebreak.Thebreaksizecould alsobeskewedtowardmediumbreakssuchasonesmallbreak,10medium breaks,andonelargebreak.Pleasediscusshowitwasdeterminedthatthe breaksizedistributionintheCASAGrandeanalysisisappropriate(i.e.,

neithertooconservativenortoonon-conservativeintermsofthedebris generation)whenexaminingthe"nalprobabilityresult(thecoremelt

frequency).RemovedResponse,Pg.2546.ByletterdatedSeptember10,2012,theNRCapprovedtherisk-informedinserviceinspection(RI-ISI)programforthethird10-yearinserviceinspec-tionintervalatSTP,Units1and2(ADAMSAccessionNo.ML12243A343).

Pleasediscussthefollowing:(a)PleasestateiftheLOCAfrequencyestimatesusedforweldsintheGSI-191submittalareconsistentwiththeLOCAfrequencyestimates usedintheRI-ISIprogram.Ifthecomparisonisappropriate,please providenumericalexamplesofthecomparison.Ifthecomparisonis notappropriate,pleaseprovideexplanation.

RequiredResponse,Pg.255(b)IftheLOCAfrequenciesforweldsarenotconsistentbetweenthetwoanalyses,(1)pleaseidentifytheandexplainwhythere areand(2)pleasediscusswhytheLOCAfrequenciesTuesday1 stMarch,2016:19:32,Page52of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproposedintheGSI-191submittalareacceptableiftheyarenotconsistentwiththatoftheRI-ISIprogram.

RequiredResponse,Pg.2551.3.5ESGB:SteamGeneratorTubeIntegrityandChemicalEngi-neeringBranch1.3.5.1Chemical1.Theexponentialprobabilitydensityfunctions(PDF)forsmall-,medium-,andlarge-breakLOCAs(e.g.,Figure5.6.4,Volume3)areshowninterms ofachemicalbump-upfactor.TheNRChasquestionsrelatedtothe conventional(non-chemical)headlosscorrelation.Thereviewofachemical bump-upfactoriscomplicatedbythefactthatitisessentiallyamultiplier onaparameterthatisconcurrentlybeingreviewedforadequacy.Please providethefollowingadditionalinformation.(a)CASAGrandecalculatestheconventionalheadlossvalueforagivenbreakandthenappliesachemicalbump-upfactorindependentof theconventionalheadloss.Pleasejustifynotcorrelatingthechemi-calbumpupfactortotheconventionalheadlosssincethesamedebris bedbothvalues.BasedontheNRCsexperienceobserv-ingtesting,headlossforagivenquantityofchemicalprecipitates shouldberelatedtoboththetypeofprecipitateandthe"ltering characteristicsofthedebrisbed.RemovedResponse,Pg.256(b)InordertohelptheNRCjudgethemagnitudeofthechemicalheadlossbump-upfactor,pleaseprovide,byperformingrealizations fortheexistingCASAGrandemodel,arelativefrequencyplotof chemicalforSTPintermsofabsoluteunits(e.g.,feetofwa-ter)forthesmall-breakLOCA(SBLOCA),medium-breakLOCA (MBLOCA),andlarge-breakLOCA(LBLOCA).Forexample,ahis-togramshowingchemicalheadloss(feet)onthex-axisandnumber ofoccurrencesonthey-axiswouldbeveryusefultotheRemovedResponse,Pg.257(c)PleaseprovideadditionaldetailsonhowtheresultsfromtheChemicalHeadLossExperiment(CHLE)testing,WCAP-16530-NP-A,"Eval-uationofPost-AccidentChemicalinContainmentSump FluidstoSupportGSI-191,"March2008(ADAMSAccessionNo.

ML081150379),calculations,andreasonableengineeringjudgment wereusedinthedevelopmentoftheexponentialPDF.Inaddition, pleasesupplythebasisforchoosingtheexponentialformofthePDF overothers(e.g.,Weibull).RemovedResponse,Pg.257(d)PleaseprovideadetailedtechnicalbasisforthemeanbumpupfactorsshownfortheSBLOCA,MBLOCA,andLBLOCA.TheNRC hasobservedheadlosstestingwherethegreatestchemicalbump-up factorsareassociatedwiththinnerbeds.Pleasediscusswhythemean bumpupfactorwouldbehigherforaLBLOCA.Pleaseexplainifit ismoreprobablethatadebrisbedforsmallerandmediumbreaks (assumingthebedcoveragecriterionismet)wouldconsistprimarily of"ber"nesthatarethemostreadilytransportabletothestrainer.

Ingeneral,"ner"berbedstendtoleadtogreaterheadloss.RemovedResponse,Pg.259Tuesday1 stMarch,2016:19:32,Page53of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION2.Pleaseexplainhowthehighestheadlossvalues(e.g.,90th,95thpercentile)obtainedusingCASAGrandecomparewiththeheadlossvaluesobtained fromtheSTPplant-speci"cstrainertestsatAldenLaboratory.Please discussbothintermsofconventionalheadloss(i.e.,beforeadditionof chemicalprecipitates)andafterchemicalprecipitateswereadded.Please discussallstrainertestresultsincludingthetestthatwasterminatedprior toadditionofprecipitates.RemovedResponse,Pg.2603.Pleaseprovidethetechnicalbasisforthe1E-05probabilityforthemaxi-mumchemicalforeachbreaksize.Theengineeringjudgmentused todeterminethatvalueappearstobearbitraryandotherexpertassessors couldeasilyreachdtconclusionsconcerningatailprobability.RemovedResponse,Pg.1814.Pleaseprovidetheresultsofasensitivitystudyrelatedtotheassumptionofthetailprobabilitythatshowshowdtassumptions(e.g.,1E-02,1E-03,1E-04)forthemaximumchemicalbump-uptailwouldthe probabilityofexceedingtheECCSpumpsNPSHcriteriaandtheimpact tothecoredamagefrequencyandlargeearlyreleasefrequency.Please evaluatethesetailprobabilitiesassumingtheconventionalheadlossis constantandequalto(a)0.5feet,(b)1.0feet,and(c)2feet.RemovedResponse,Pg.2615.SincetheSTPchemicaleevaluationisheavilydependentonengineer-ingjudgment,theNRCneedsclari"cationregardingthesensitivity ofvariousassumptionstotheoverallriskinformedevaluation.Inaddition tothesensitivitystudyrequestscontainedinotherchemicalRAis (e.g.,RAI#4),pleaseevaluatethekeychemicalareaassumptions (e.g.,bumpupfactors,typeofdistribution,etc.)andprovidesensitivity studiesthatwillhelpthetoevaluatehowchangesinthoseassump-tionswillaltertheprobabilityoffailures.Pleaseidentifyanyassumptions thatarecorrelatedandexplainhowthecorrelationwasconsideredinthe

analysis.RemovedResponse,Pg.2616.Pleasedescribetherelativechemicalcontributionsfromthesprayedma-terialscomparedtothesubmergedmaterials.Pleasestateifthechemical modelinputintoCASAassumesa"xed,6.5-hoursprayduration.Ifso, pleasediscusstheprobabilityofcontainmentsprayoperatingatatime beyond6.5hoursfollowingaLOCAandhowthechemicalanalysis wouldbechanged.Pleasedescribeifanysensitivitystudywasperformed onthespraytimewithrespecttohowitmaythechemicalsource term,theprobabilityofprecipitation,andultimatelytheGSI-191failure modes.RemovedResponse,Pg.2647.CHLETankTests3and4wereperformedwithexcessivequantitiesofaluminumrelativetotheplantandwithatemperaturepro"leintended toinducechemicalprecipitation.Thesetestsresultedinchemicalprecipi-tationandprovidedusefulinformationrelatedtoheadlossloopresponse tochemicalprecipitates.Theexistingtestsdonotappeartoaddressthe extentofdeviationfromthebestestimateplantconditionsthatcouldre-sultinchemicalprecipitation.Onepotentialmethodtoinformengineering judgmentwithrespecttochemicalprobabilitiescouldbeaseriesTuesday1 stMarch,2016:19:32,Page54of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONofsmallerscaletestsdesignedtoevaluatethethresholdconcentrationsofspeciesthatcouldresultinprecipitation.Forexample,testscouldbede-signedtoevaluatehowmuchaluminumorcalciuminsolutionwouldcause precipitationthatmayresultinsigni"cantincreasesinheadloss.These typesoftestswereincludedintheoriginalchemicaltestplansbut wereapparentlycancelled.Pleasediscussanyplansforsmallerscaletesting toinvestigatethresholdvaluesforprecipitationandwhetherthatinforma-tionwouldprovidegreatercon"denceindeterminingtheprobabilitythat apost-LOCAplantconditionwouldresultinchemicalprecipitateforma-tion.Iftherearenoplansforadditionaltests,pleaseprovidejusti"cation forthisengineeringjudgment.RemovedResponse,Pg.1828.TheSTPchemicalanalysisassumesnoprecipitationpriortothesumppoolcoolingto140degreesFahrenheitItispossible,however, toprecipitateacalciumphosphateprecipitateathighertemperaturesif tdissolvedcalciumispresent.PleaseexplainiftheCASAGrande modelincludescalciumsourcessuchasconcretedust,concreteablatedby thejet,andotherplantmaterialssuchasinsulation.Pleasestateifthere isapotentialforsomepipebreakstoproduceenoughcalciumsuchthat formationofaprecipitateatagreaterthan140temperatureshouldbe included.Sincesomeprecipitatescanformattemperaturesgreaterthan 140pleaseexplainhowincreasingthetemperaturethresholdinCasa Grandetheoutcomes.RemovedResponse,Pg.2659.Pleasedescribethekeysourcesofuncertainty(aleatoryandepistemic)associatedwiththedissolutionmodelandthesolubilitylimitsandhow isthisuncertaintyfactoredintotheprobabilitydensityfunctionsandthe chemicalbumpupfactors?RemovedResponse,Pg.26510.Thefollowingparametersdonotappeartobeconsideredinthesimpli"edapproachusedtoquantifychemicalforSTP:poolchemistry,pool pH,andtheamountsofaluminum,calcium,andzinc.Iftheseitemsare notconsidered,pleaseprovidejusti"cationforacceptabilityoftheanalysis withouttheirconsideration.RemovedResponse,Pg.26611.TheconclusionscontainedindocumentCHLE-014,T2LBLOCATestReport,"(letterdatedOctober13,2013,availableinADAMSAccession No.ML13323A873)state,inpart,Chemicalproductsdidformunderthe simulatedSTPLBLOCAconditionsbutprimarilywereadheredtothe galvanizedcoupons.Inaddition,CHLE-020,TestResultsfora10-day chemicaltestsimulatingLBLOCAconditions(T5),statesonpage 10,ThehighturbidityatthebeginningofTestsT5andT2shownin Figure3bmightbecausedbydetachmentofzincparticlesfromthezinc couponsandgalvanizedsteelcouponsduetothehightemperatureduring the"rst80minutesofthetest.Page75ofVolume6.2states,Althougha zinc(Zn)productwasobservedtoformunderSTPLOCAtestconditions, itwasnotincludedinthisanalysissincetheproductwasdetermined tobecrystallineandmainlyadheretostructureswithincontainmentas opposedtoreadilytravelwithsolution.Basedoninternationalexperience,Tuesday1 stMarch,2016:19:32,Page55of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONFramatomeANP,Inc.reporttitled,In"uenceofCorrosionProcessesontheProtectedSumpIntakeafterCoolantLossAccidents,December2006 (ADAMSAccessionNo.ML083510156),zinccorrosionproductdislodged byfallingwatercausedasigni"cantincreaseinheadloss,pleasediscuss:(a)IffollowingaLOCA,watereitherfallingfromapipebreakorfromotherlocationsinthecontainmentbuildingcoulddislodgezinccor-rosionproductfromgalvanizedsteelsurfacesthatcouldtransportto thestrainer.RemovedResponse,Pg.186(b)Whetherchemicalcontributionsfromzincshouldbeconsid-eredaspartoftheSTPchemicalanalysis.

RequiredResponse,Pg.18612.TheCHLEtestfacilityincludedthreeparallelverticalheadlossloopsthatwereintendedtoallowmultiplebedevaluationswitheachtest.Thetest resultssuggesttherewaspotentiallysomebiasinheadlossresultsbetween thethreeloops.Pleasedescribeanyevaluationsthatwereperformedand lessonslearned.Also,pleasedescribeanysigni"cantmodi"cationsthat weremadetothefacilityloopduringthecourseoftestingandhowthose modi"cationsmayhavetheresults.RemovedResponse,Pg.15713.ThealuminumsourceforCHLEtestswasaluminumremovedfromtheplant.Theswasdescribedinthetestdocuments(e.g.,

CHLE-012)asanon-homogenoussamplewithunknownconstituentsfrom yearsofusewhichremainedaftercleaning.DuringtheNRCsvisitto observeCHLEtesting,theobservedwhatappearedtobeagrout-like materialcoveringarelativelysmallportionofatestsample.Thesub-mergedssamplesweretakenfromthesideoftheand hadattextureandappearancethanthesamplescutforthevapor space.Analysisofunusedindicatedthepresenceofaluminum phosphateandaluminumoxide/hydroxidescales.Thepre-existingscale mayhavereducedthealuminumreleasedbycorrosion.Sincethecorrosion ofaluminumcanhaveasigni"cantimpactonwhetherchemicalprecipi-tatesform;(a)PleasedescribethestepstakentoensurethatthesurfaceconditionofthesusedintheCHLEtestsisrepresentativeofthe remainingaluminumintheplant.RemovedResponse,Pg.158(b)Pleaseexplainifthecorrosionbehaviorofthedtpartsofthe(i.e.,thepartusedforsubmergedsamplesandthepart usedforvaporsamples)wasevercomparedbyplacingtheminthe exactsametestconditions,suchasinabenchtest.RemovedResponse,Pg.159(c)PleaseexplainifthessurfaceconditionwasevaluatedtodetermineifaLOCAjetorthethermaltransientfromaLOCAwould causetheoxidetospall,potentiallyresultinginagreatercorrosion ratethanwasobservedduringtheCHLEtesting.RemovedResponse,Pg.15914.PleasediscusshowuncertaintiesfromthefollowingitemsareconsideredintheSTPchemicalanalysis:Tuesday1 stMarch,2016:19:32,Page56of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(a)Radiationonprecipitateformation.

RequiredResponse,Pg.268(b)Radiationondebrisbeddegradation.Inaddition,forthisitem,thesubmittalstates(Volume6.2,page84)thatbreakdownofthe "berbedisnotconsideredtobeasigni"cantissueduetosimilar materialsbeingusedfor"ltrationmediaforhighactivityparticulate.

Pleasediscusshowthe"lterservicelifeinthereferencedapplication comparestotheECCSmissiontimefollowingaLOCA.

RequiredResponse,Pg.268(c)Eofunquali"edcoatingsdegradation.Forexample,pleaseex-plainifleachedchemicalsfromthecoatingsatSTPcontributeto potentialchemicalPleaseexplainifthecoatingsthemselves becomeadebrissourcethatismoreproblematicthanparticulates (e.g.,gelatinous).Aspartoftheresponse,pleasecomparethecoatings testedinthereportreferencedintheLARtotheSTPplant-speci"c unquali"edcoatings.

RequiredResponse,Pg.27015.TheCHLEtestssimulateda15-inchLBLOCA.PleasedescribehowtheCASAGrandechemicalmodeldeterminesthechemicalsourcetermfor tsizebreaks,suchasasmallerthan15-inchLBLOCAoralarger than15-inchLBLOCA.Inaddition,pleaseexplainifCASAGrandecon-sidershowasmallerbutpotentiallymorefocusedjetthattakeslongerto blowdownmaythecalciumandaluminumconcentrations.RemovedResponse,Pg.27016.Volume1,Section1.2.6,"ChemicalReleaseandPrecipitationModel,"statesthatseveralscenarioswereinvestigatedusingtheWCAP-16530-NP-Aformulaforchemicalrelease.Thescenariosusedtcombinations ofliquidtemperature,pH,watervolume,and"berquantityforseveral tbreaksizesuptoadoubleendedguillotinebreak.Pleaseclarify ifTables2.5.34and2.5.35inVolume6.2summarizetheresultsofthese investigations.Pleaseprovidetheminimumandmaximumvaluesforthe pH,"berquantity,andwatervolumeinthetables.Alsopleasediscussif post-LOCAvaluescouldreasonablyexceedtheminimumandmaximum valuesusedintheevaluations.Forexample,pleaseexplainifitisplausible forthepHtobegreaterthanwasassumedtobethemaximumpH.RemovedResponse,Pg.27117.Page187ofVolume3statesthechemicalbump-upfactorshouldneverbelessthanone,andthereisapracticalmaximumabovewhich alleventswillleadtosumpfailure.Pleasediscussinmoredetailthe approximatevalueofabumpupfactorthatwillleadtosumpfailure.

Pleaseprovidethevaluesforconventionalheadlossthatareassumed.RemovedResponse,Pg.18718.Volume6.2,"Item5.a.6:CorrosionandDissolutionModel,"onpage72statesthefollowing:Thedeterminationofwhetherachemicalproductwouldformwasbasedonacombinationofengineeringjudgmentandlimited thermodynamicmodeling.Thetotalquantityofmaterialreleased wasnotassumedtofullyprecipitateintochemicalproducts.In-stead,solubilitylimitsofchemicalproductsexpectedtoform...Tuesday1 stMarch,2016:19:32,Page57of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONwerecalculatedasafunctionoftemperatureandpHusingVi-sualMINTEQtodeterminethelowestconcentrationofmetal requiredforproductformationfromtherangeofselectedcon-ditions.Sodiumaluminumsilicateandaluminumoxyhydroxide arethealuminumproductsdescribedaspossibleprecipitatesin WCAP-16530-NP-A;howeveronlythealuminumhydroxidesol-ubilitylimit(LogKof10.8...)wasconsideredinthisanalysis sinceitwasdeterminedasasuitablesubstituteforsodiumalu-minumsilicateinheadlosstesting....Calciumphosphate(Log Kof-28.25)solubilitylimitswerealsoevaluated.Thelowestconcentrationofmetalsrequiredproductsweredeter-minedbyidentifyingtherangeof7.0to7.3atade"nedtemper-ature.Usingthisapproach,theconcentrationofaluminumexpectedtoresultinformationofachemicalproductisapproximately4.9milligramperliter (mg/L).Thecalciumconcentrationexpectedtoresultintheformation ofachemicalproductwas0.8mg/L.Thesevalueswereusedtoassess thepresenceofchemicalproductformationfromthecalculatedmaterial

release.(a)PleasedescribewhytheNRCsjudgmentthataluminumoxy-hydroxideandsodiumaluminumsilicateprecipitatespreparedusing theWCAP-16530-NP-Amethodcanbesubstitutedforeachotherin headlosstestingisrelevanttosolubilitywhenevaluatingwhetheran aluminumbasedprecipitatewillforminapost-LOCA"uidcontain-ingdissolvedaluminum.

RequiredResponse,Pg.272(b)UsingEquation4intheArgonneNationalLaboratoryTechnicalLetterReportAluminumSolubilityinBoronContainingSolutions asafunctionofpHandTemperature,datedSeptember19,2008 (ADAMSAccessionNo.ML0918b10696),thelowestaluminumsolu-bilityinthepHrange7.0to7.3isapproximately2.7partspermillion (ppm).Pleasediscusshowtheanalysisresultswouldbeby assumingthealuminumsolubilitywas2.7mg/Linsteadof4.9mg/L.RemovedResponse,Pg.272(c)Thediscussionstatesthatcalciumphosphatesolubilitylimitswereevaluated.Figure2.5.34(Volume6.2)showsthecalciumhydroxide solubilityinborated-TSP[trisodiumphosphate]solution.Pleasedis-cusstherationaleforthe0.8mg/Lsolubilityforcalciumandwhether itwasbasedonacalciumhydroxidesolubilityorcalciumphosphate solubility.RemovedResponse,Pg.27219.ThecaptionforFigure5.6.6(Volume3)statesTypicalsampleofsump-strainerheadlosshistoriesgeneratedundertheassumptionofexponential chemicalfactorandarti"cialhead-lossin"ation.Pleaseclarifyifthe arti"cialheadlossin"ationreferstotheNUREG/CR-6224,Parametric StudyofthePotentialforBWRECCSStrainerBlockageDuetoLOCA GeneratedDebris,October1995(ADAMSAccessionNo.ML083290498),

correlationmultipliedby5orsomeothervalue.RemovedResponse,Pg.161Tuesday1 stMarch,2016:19:32,Page58of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION20.Pleasediscusswhatbenchmarkingwasperformedwitha)STPspeci"cstrainertestsandb)industrytestdatawithsimilarconditionsforthe baselineheadlossandchemicalbumpupfactor.RemovedResponse,Pg.18821.TheamountofcrudreleasedfollowingaLOCAisestimatedtobe5-24pound-mass(Ibm)(Volume6.2,page85).FortheCASAGrandeanalysis, pleasediscussthequantityofcrudorotheractivateddebristhatisassumed toreachthestrainerandhowitheadloss.Pleasecomparethe totalcrudquantityestimatedwiththeamountofcrudcollectedduringa controlledcrudburstperformedatthebeginningofrefuelingoutages.

RequiredResponse,Pg.27322.Atotalof"veCHLEtanktestswereperformedtoevaluateSTPplant-speci"cchemicaltests.CHLETests1and2wereintendedtoeval-uateanMBLOCAandanLBLOCA,respectively.Pleaseaddressthefol-lowingquestionsrelatedtoTests1and2:(a)PleasediscusswhythetestscreendebrisbedisanacceptablemethodfordetectionofchemicalprecipitatesgiventheearliertestCHLE-010,CHLETankTestResultsforBlendedandNEI[NuclearEnergy Institute]FiberBedswithAluminumAddition,thatshowednohead lossresponseeveninthepresenceoflargequantitiesofaluminum oxyhydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.Note:AdditionaldetailsareavailableinaSeptember 6,2012,meetingsummarydatedOctober4,2012(ADAMSAccession No.ML12270A055).

RequiredResponse,Pg.189(b)Pleasedescribewhytheuseofonlyaluminumand"berglassintheMBLOCAtestadequatelyrepresentstheplantspeci"cenvironment.

RequiredResponse,Pg.1911.3.5.2Coatings1.Pleaseprovidethebasisfortheunquali"edepoxysizedistributionreportedinTable2.2.18inVolume3.TheNRChaspreviouslyallowedlicensees toassumethatdegradedquali"edepoxycoatingsfailinpieceslargerthan "nes.Thisallowancewaslimitedtoepoxycoatingsthatwereoriginally quali"edandhavebecomedegraded.Thesametreatmenthasnotbeen acceptedforepoxycoatingsthatwereunquali"ed,sincethesearetypi-callylessrobustcoatingsystemsthatwoulddisintegrateinto"nes.Please specifytheepoxycoatinginquestionandprovideabasis(i.e.,testing)for assumingitfailsinpieceslargerthan"nes.RemovedResponse,Pg.2732.Table2.2.16inVolume3providesthequantityofquali"edcoatingsgen-eratedwithintheZoneofIn"uence(ZOI)forvariouspipediameters.The ZOIusedtocalculatethesequantitiesisnotprovided.Pleaseprovidethe ZOIusedforbothepoxyandinorganiczinc(IOZ)quali"edcoatings(e.g.,

epoxy=4D,IOZ=10D).

RequiredResponse,Pg.2743.Section5.4.5,Unquali"edCoatingDebris,inVolume3statesthatthetotalfailurefractionisassumedtobe100%forallunquali"edcoatings.

Giventhisstatement,pleasedescribethesigni"canceofthefailurefraction analysisprovidedonpages11through17inVolume6.2.PleaseclarifyifTuesday1 stMarch,2016:19:32,Page59of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthefailurefractionanalysisisusedinanymannerintheCASAmodeloriftheunquali"edcoatingsarealwaysassumedtohavea100percentfailure

fraction.RemovedResponse,Pg.2744.Forunquali"edcoatingsthatarenotlocatedintheuppercontainment,theNRCsunderstandingisthat100percentofthecoatingsareas-sumedtofailandareavailablefortransporttothestrainer.Thealso understandsthat100percentofthecoatingsthatarecalculatedtotrans-porttothestrainerareassumedtoarriveatthestraineruniformlyover the"rst36hours.Pleasecon"rmthatthesunderstandingiscorrect.

Also,pleaseprovidedetailsrelatedtotheunquali"edcoatingfailureas-sumptionsintermsofpercentages,timingandquantitiesthatarriveat thesumpstrainer.RemovedResponse,Pg.2745.Equations27and28(page157,Volume3)refertoF(t)asthefractionofcoatingsthatfailduringaspeci"ctimeperiod.Pleaseprovidethevalue ofF(t)anddescribetheanalysisperformedtoarriveatthatvalueforthe timeframeduringwhichuppercontainmentsprayisactiveandcapableof transportingcoatings(theinitial24hours).PleasestateifF(t)isthesame forallunquali"edcoatingtypes.Inaddition,pleaseprovidethecumulative massofunquali"edcoatingsthatfailintheuppercontainmentinthe"rst 24hoursinthecurrentanalysis.RemovedResponse,Pg.2776.TheVolume6.2responsestorequestforsupplementalinformation,indi-catethatthefailuretiminganalysisreliesheavilyon"lterdatafromthe EPRIDBAtestingoforiginalequipmentmanufacturer(OEM)coatings.

PleaseaddressthefollowingquestionsregardingSTPsuseofthistest

data:(a)PleasedescribewhatSTPhasdoneintermsofdocumentationreviewortestingofplantmaterialsinordertoensurethattheplant-speci"c unquali"edcoatingsatSTParethesameasthecoatingsusedinthe EPRItesting.

RequiredResponse,Pg.280(b)The"nalproprietaryEPRIreportonOEMCoatings(EPRI1011753,DesignBasisAccidentTestingofPressurizedWaterReactorUn-quali"edOriginalEquipmentManufacturerCoatings.FinalReport,September2005),statesthat,Duetotheprohibitivenatureofthe task,therewasnoattempttoquantifytheamountofdebriscaptured inthe"lters.Thistestingincludedmanydtcoatingtypeswith varyingcolor,density,andconstituentparticlesize.Theautoclave wasnotopenedandthetestedcomponentswerenotexamineduntil theentiretestwascomplete.TheNRCcouldnotdetermineif lightercoatingswhichwouldbelessvisibleona"lter(andcertainly lessvisibleonaphotoofa"lter)failedatthesamerateasdarker coatingsoriftheymayhavebeenpresentononeormoreofthe"lters removedearlyinthetest.Giventhisinformationandthefactthat thetestersstatedthattheymadenoattempttoquantifydebrison the"lters,pleaseprovideadditionaljusti"cationforusingthistest datatoassignafailuretimetounquali"edcoatings.RemovedResponse,Pg.280Tuesday1 stMarch,2016:19:32,Page60of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(c)TheEPRIOEMreportalsostatesthat,Withregardtotimingofthecoatingfailures,the"ltersdonotdemonstrateade"nitivetime offailure,howeverinsubjectiveterms,itappearsthatmuchofthe failureoccurredinthe24-to48-hourtimeframe.STPseekstoreduce thetransportedunquali"edcoatingdebrisfromuppercontainmentby 94percentcomparedtoadeterministicapproach(100percentfailure inadeterministicevaluation,6percentforSTP).TheNRCis notpersuadedthatasubjectivereviewofphotographsfromatest performedin2005isadequatejusti"cationfortheproposedfailure timing.Pleaseprovideadditionaljusti"cationforthecurrentanalysis orprovidearevisedvalueforthefailuretiming.RemovedResponse,Pg.2807.Pleasedescribeanyongoingcontainmentcoatingconditionassessmentprogram.Pleaseincludethefrequencyandscopeoftheinspections,accep-tancecriteria,andthequali"cationofpersonnelwhoperformcontainment coatingsconditionassessmentinspections.

RequiredResponse,Pg.2811.3.6SCVB:ContainmentandVentilationBranch1.InsupportofEnclosure2-3,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion[GDC]38,pleaseprovidethe following:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-38.

RequiredResponse,Pg.192(b)Pleasedescribethespeci"crequirementsofGDC-38thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.1922.InsupportofEnclosure2-4,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion41,pleaseprovidethefollowing:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-41.

RequiredResponse,Pg.192(b)Pleasedescribethespeci"crequirementsofGDC-41thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.1923.Enclosure3,page4,paragraphUseofaRisk-InformedApproachtoRe-solvingGSI-191,states:Thedesignandlicensingbasisdescriptionsofaccidentsrequir-ingECCSoperation,Includinganalysismethods,assumptions, andresultsprovidedinUFSAR[UpdatedFinalSafetyAnalysis Report]Chapters6and15remainunchanged.Thisisbasedon thefunctionalityoftheECCSandCSSduringdesignbasisacci-dentsbeingcon"rmedbydemonstratingthatthecalculatedrisk associatedwithGSI-191forSTPUnits1and2isVerySmall andlessthantheRegionIllacceptanceguidelinesde"nedbyRG

1.174.Tuesday1 stMarch,2016:19:32,Page61of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONThecurrentlicensingbasiscontainmentanalysismethodologyusedtocon-"rmtheadequacyofthecontainmentheatremovalsystem(whichcomplies with10CFR50AppendixAGDC-38)describedintheUFSARist fromtheproposedmethodologywhichresolvesGSI-191onarisk-informed basisandproposesanexemptionrequestfromGDC-38.Forexample:(a) inthesinglefailureassumptionintheproposedandcurrent analysis;(b)computercodesRELAPforLOCAmassandenergy(M&E) release,andMELCORfortheLOCAsumptemperatureresponseareused intheproposedanalysis,andSATAN-VI,WREFLOOD,FROTHareused forM&EreleaseandCONTEMPT4/MODSisusedforsumptemperature responseinthecurrentanalysis;and(c)theproposedanalysisinputsand assumptionsarerequiredtobeconservativefromGSI-191perspectiveand alsorequiredtobeconservativeforsumptemperatureresponsewhereas thecurrentanalysisinputsandassumptionsareconservativeforsump temperatureresponse,(a)PleasejustifywhytheUFSARlicensingbasisdescriptionofthemethod-ologyusedforcon"rmingtheadequacyofcontainmentheatremoval systemwhichcomplieswithGDC-38shouldnotbereplacedwiththe proposedlicensingbasismethodologywhichtakesanexemptionfrom GDC-38.complieswithGDC-38shouldnotbereplacedwiththepro-posedlicensingbasismethodologywhichtakesanexemptionfrom

GDC-38.RequiredResponse,Pg.193(b)Tabulatethedbetweentheinputsandassumptionsbetweenthecurrentlicensingbasiscontainmentanalysisthatcalculatesthe mostlimitingsump"uidtemperaturepro"leforavailableNPSHcal-culationandtheproposedcontainmentanalysisperformedforrisk-informedGSI-191.Pleasejustifythattheinputsandassumptionsin theproposedmethodologyareconservativefrombothGSI-191and sumptemperatureresponseperspectives.

RequiredResponse,Pg.193(c)IncasetheUFSARlicensingbasisdescriptionofthecontainmentheatremovalsystem,includingitsrelatedmassandenergyrelease analysismethodology,isrequiredtobereplaced,pleaseprovidethe revisedUFSARinputforNRCreviewandapproval.

RequiredResponse,Pg.1964.Thecurrentlicensingbasismethodologyfortheiodineremovalisdoc-umentedinUFSARSection6.5.2,ContainmentSpraySystem-Iodine Removal.TheiodineremovalisaccomplishedbytheCSSwhichmeets therequirementsof10CFR50AppendixAGDC-41.Theproposedrisk-informedGSI-191methodologytakesexemptionfromcompliancewith GDC-41requirements.(a)PleasejustifywhytheUFSARlicensingbasisdescriptionoftheiodineremovalshouldnotberevisedwiththeproposedmethodologywhich takesexemptionfromGDC-41.

RequiredResponse,Pg.196(b)PleasetabulatethedbetweentheinputsandassumptionsbetweenthecurrentlicensingbasiscontainmentatmospherecleanupTuesday1 stMarch,2016:19:32,Page62of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONmethodandtheproposedcontainmentatmospherecleanupwhichtakesexemptionfromtheGDC-41requirements.

RequiredResponse,Pg.197(c)IncasetheUFSARlicensingbasisdescriptionoftheiodineremovalsystemisrequiredtobereplaced,pleaseprovidetherevisedUFSAR inputforNRCreviewandapproval.

RequiredResponse,Pg.1975.InsupportofVolume6.2,pleaselistthedbetweentheheatsinksinthecurrentlicensingbasiscontainmentanalysisdocumentedintheUF-SARTables6.2.1.1-7and6.2.1.1-8andintheproposedcontainmentanal-ysisforrisk-informedGSI-191.Pleaseprovidejusti"cationincaseswhere theconservatismisreducedintheproposedanalysis.

RequiredResponse,Pg.1976.InsupportofVolume6.2,pleaselistthedbetweentheLOCAsurfaceheattransfermodelforheatsinksinthecurrentlicensingbasis analysisdocumentedinUFSARTable6.2.1.1-9andthemodelinthepro-posedcontainmentanalysisforrisk-informedGSI-191.Providejusti"ca-tionfortheincasetheconservatismisreducedintheproposed

analysis.RequiredResponse,Pg.1977.NUREG-0800,StandardReviewPlanfortheReviewofSafetyAnalysisReportsforNuclearPowerPlants:LWREdition(SRP),Section6.2.1.5, MinimumContainmentPressureAnalysisforEmergencyCoreCooling SystemPerformanceCapabilityStudies,describestheminimumcontain-mentpressureanalysisforECCSperformancecapability.RG1.157,Best EstimateCalculationforEmergencyCoreCoolingSystemPerformance, May1989(ADAMSAccessionNo.ML003739584),Section3.12.1,Con-tainmentPressure,providesguidanceforcalculatingthecontainment pressureresponseusedforevaluatingcoolingeenessduringthepost-blow-downphaseofaLOCA.UFSARSection6.2.1.5documentsthecurrentminimumcontainmentpres-sureanalysisforperformancecapabilitystudiesoftheECCS.Pleasede-scribetheproposedcontainmentanalysis,includingassumptionsandin-puts,performedforthecalculationofminimumcontainmentpressurein-putfortheECCSanalysisthatcalculatesthepeakcladdingtemperature forrisk-informedGSI-191.Pleasejustifythattheinputsandassumptions areconservativeforthepurpose.

RequiredResponse,Pg.1978.Volume6.2,page117,Item5.a.14,In-VesselThermalHydraulicAnal-ysis,listssixscenariossimulatedusingthe3DVessel-1DCoreModel.

PleasedescribeandjustifythebasisforselectionoftheseLOCAbreaks

scenarios.

RequiredResponse,Pg.1989.InsupportofEnclosure2-2,RequestforExemptionfromCertainRe-quirementsofGeneralDesignCriterion35,pleaseprovidethefollowing:(a)Pleaselistthespeci"cSTPplantsystemsthatwillnotmeettherequirementsofGDC-35.

RequiredResponse,Pg.198(b)Pleasedescribethespeci"crequirementsofGDC-35thatwillnotbemetbyeachoftheplantsystemslistedinresponsetoitem(a)above.

RequiredResponse,Pg.199Tuesday1 stMarch,2016:19:32,Page63of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.3.7SNPB:NuclearPerformanceandCodeReviewBranch1.PleaseprovidethefollowinginformationfortheSTPNuclearSteamSup-plySystems(NSSSs):(a)Volumeofthelowerplenum,coreandupperplenumbelowthebottomelevationofthehotleg,eachidenti"edseparately.Also,pleaseprovide theheightsoftheseregionsandthehot-legdiameter.

RequiredResponse,Pg.199(b)Loopfrictionandgeometrypressurelossesfromthecoreexitthroughthesteamgeneratorstotheinletnozzleofthereactorvesselforsteady statefullpoweroperation.Also,providethelockedrotorreactor coolantpump(RCP)k-factor.Pleaseprovidethemass"owrates, "owareas,k-factors,andcoolanttemperaturesforthepressurelosses provided(upperplenum,hotlegs,SteamGenerators(SGs),suction legs,RCPs,anddischargelegs).PleaseincludethereducedSG"ow areasduetopluggedtubes.Also,providethelossfromeachofthe intactcoldlegsthroughtheannulustoasinglebrokencoldlegand theequivalentloopresistanceforthebrokenloopandseparatelyfor theintactloop.Pleaseidentifythe"owarea(hydraulicdiameter)on whichthek-factorsarebased.

RequiredResponse,Pg.201(c)CapacityandboronconcentrationoftheRWST.

RequiredResponse,Pg.203(d)Capacityofthecondensatestoragetank(CST).

RequiredResponse,Pg.203(e)Flushing"owrateatthetimeofswitchtosimultaneousinjection.

RequiredResponse,Pg.203(f)Highpressuresafetyinjection(HPSI)runout"owrate.

RequiredResponse,Pg.205(g)Capacitiesandboronconcentrationsforhighconcentrateboricstor-ageacidtanks,ifpartofsystem.

RequiredResponse,Pg.205(h)FlowrateintotheRCSfromtheboricacidstoragetanks,ifapplica-ble.RequiredResponse,Pg.205(i)TimetoemptytheRWST(allpumpsoperating).

RequiredResponse,Pg.205(j)Minimumcontainmentpressureorcontainmentpressureversustimegraph.Response,Pg.205(k)Sumpboricacidconcentrationversustime.

RequiredResponse,Pg.207(l)MinimumRWSTtemperature.Response,Pg.207(m)Injectiontemperatureversustimefromsumpduringrecirculation.

RequiredResponse,Pg.2072.Pleaseprovidethefollowingelevationdata:(a)bottomelevationofthesuctionleghorizontallegpipingandcoldleg diameter RequiredResponse,Pg.208(b)topelevationofthecoldlegattheRCPdischargeResponse,Pg.208(c)topelevationofthecore(alsoheightofcore)

RequiredResponse,Pg.208(d)bottomelevationofthedowncomer RequiredResponse,Pg.2083.Pleaseprovidethelimitingbottomandtopskewedaxialpowershapes RequiredResponse,Pg.209Tuesday1 stMarch,2016:19:32,Page64of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION4.Pleaseprovidethelatestanalysisorreferenceshowingthetimingforboricacidprecipitationforthelimitinglarge-breakandsmall-breakLOCAs.

RequiredResponse,Pg.2835.Justi"cationanddescriptionofthemethodologyusedtocomputethesumpboricacidconcentrationversustime.

RequiredResponse,Pg.2101.3.8SRXB:ReactorSystemsBranchTheNRCrequeststhelicenseetoprovidethefollowing:1.RELAP-3Dinputdecksforthesecaseswitha3-Dvesseland1-Dcore:(a)SteadystatecaseinColdLeg(b)MediumBreakLOCA(6)inColdLeg(c)Double-EndedGuillotine(DEG)BreakinColdLeg(d)Coreblockageinput"le RequiredResponse,Pg.1612.RELAP-3Dinputdecksforthesecaseswitha3-Dvesseland3-Dcore:(a)SteadystatecaseinColdLeg(b)MediumBreakLOCA(6)inColdLeg(c)DEGBreakinColdLeg(d)DEGBreakinColdLegwithmaximumboron(e)Coreblockageinput"le RequiredResponse,Pg.1613.ConversiontablesbetweenRETRANandRELAP-3D(SouthTexasProjectPowerPlantRETRAN-RELAP-3DConversionTables?

RequiredResponse,Pg.1614.Documentationdescribingmodelveri"cation(SouthTexasProjectPowerPlantRELAP-3DSteady-statemodelVeri"cation)

RequiredResponse,Pg.1615.Table2.2.1inVolume3providesresultsforsumpswitchovertimebasedonthebreaksizeduringalossofcoolantaccident(LOCA).Theapplication statesthatthetimingforswitchovertorecirculationisdependentonthe volumeofwaterintheRWSTandthetotalECCSandCSS"owrate.(a)PleaseprovidetheassumptionsusedforthevolumeofwaterintheRWSTfortheresultsinTable2.2.1.Pleaseprovidejusti"cationfor useoftheseassumptions.RemovedResponse,Pg.161(b)PleaseprovidetheECCS"owrateandCSS"owrateforeachbreaksizeinTable2.2.1.Required(strnr.pen.)Response,Pg.162(c)Pleaseexplainhowsumpswitchovertimeiscalculatedbasedontheresponsestoa.andb.above.RemovedResponse,Pg.1626.Section2.2.1inVolume3describestheterminationcriteriaforcontain-mentsprays.Oneofthecriteriatoterminatecontainmentspraysisthat containmentpressurehasdroppedbelow6.5psig.Pleaseprovideplotsfor containmentpressureversustimeforarangeofbreaksizestoverifypres-suredropsbelowtheterminationcriteriaof6.5poundspersquareinch gauge(psig)before6.5hours.Removed(NoRCBovepressure)Response,Pg.163Tuesday1 stMarch,2016:19:32,Page65of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION7.Switchovertohot-leginjectionisstarted5.5hoursafterthebeginningoftheLOCAeventandisassumedtobecompletedbetween5.75and6hours.(a)PleasesummarizetheEmergencyOperatorProcedures(EOPs)thatdirecttheoperatorstotakethisactionandanassociatedtimelineof theoperatorkeyactionsifthiseventweretooccur.

RequiredResponse,Pg.163(b)Pleaseprovideajusti"cationthatdemonstratesthe15-30minuteresponsetimeisachievableduringswitchovertohotleginjection trainingscenarios.Inthejusti"cation,pleaseincludetheresultsof simulatorrunsandtraininglogs.

RequiredResponse,Pg.1638.Table2.2.14(Volume3)showssafetyinjection(SI)"owratesfornominaloperatingconditions.Pleasejustifytheuseofnominalconditionsversus theuseoflimitingconditionswhenanalyzingLOCA.

Required(strainerpen-

etration)Response,Pg.1649.Pleasedescribethetermstotalsump"ow,totalSl"ow,andECCS"ow.Pleaseincludeifhighheadsafetyinjection(HHSI),lowheadsafetyinjec-tion(LHSI),orCSSisapartofeachde"nition.Required(strnr.pen.)Response,Pg.1641.3.9SSIB:SafetyIssueResolutionBranch

• ZOI1.Volume3,Table5.3.1listsDoubleEndedGuillotineBreak(DEGB)equivalentdiametersandTable5.3.2listscomputeraideddesign (CAD)DEGBvalues.Thesevaluesarecalculatedbydoublingthe singlesidedbreakareaandthencalculatinganequivalentpipediam-eter.ApprovedZOIsarebasedondoublingthevolumeofsinglesided breakjets(calculatedbytheAmericanNationalStandardsInstitute (ANSI)model)andcalculatingaradiusforaspherebasedonthat volume.PleasedescribehowtheCADDEGBvaluescalculatedby Equation22ofVolume3areused.

RequiredResponse,Pg.166

• DebrisCharacteristics2.PleaseprovidethesizedistributionsforNukonandThermalWrapdebriscreatedbythepostulatedLOCAjet(percentageofeachsize categorycreated).Pleaseprovidethemethodologyused,including thebases,todeterminethesizedistributions.Pleaseprovideinfor-mationregardingwhetherthedistributionisasimplepercentageof allgenerated"brousdebrisorbasedonthedistanceoftheinsulation fromthebreak(Volume3,Sections2.2.15,InsulationDebrisSize Distribution,4.2,StructuresInformationProcessFlow,and5.4.2, InsulationDebrisSizeDistributionModel).

RequiredResponse,Pg.1663.PleaseclarifyifthematerialpropertiesofdebrislistedinTable2.2.21ofVolume3areusedintheheadlosscorrelation.Ifso,pleasestateif varyingthesizesoftheparticlestoamorerealisticdistribution theresultssigni"cantly.Explainhowtheparticulatedebristypesthat havesizedistributionsareimplementedinthecorrelation.Pleaseex-plainwhethertheuncertaintyofthesizedistributionofthematerialsTuesday1 stMarch,2016:19:32,Page66of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcanthepermeabilityofthedebrisbedandthereforetheheadloss.Isthisuncertaintysigni"cant,andifso,pleasestatehowisit accountedforintheSTPmodel.RemovedResponse,Pg.285

• Transport4.Pleaseprovidejusti"cationforassumption6.h.i.ofVolume3(page78).AccordingtoTable2.2.22ofVolume3,linebreaksbelowSGand surgelineresultinagreaterpercentageofsmalldebrisbeingblown directlytolowercontainment.Thisdebrisisconsideredtoenterthe pooldirectlywhiledebrisblowntouppercontainmentmaybeheldup.PleaseexplainwhytheSGcompartmenttransportfractionsare consideredtobeconservativecomparedtotheseotherbreakloca-

tions.RequiredResponse,Pg.2855.Pleaseexplainassumption6.h.vofVolume3(page79).Pleasede-scribehowthenumberofstrainersinservicepool"lltrans-port.Itappearsthatthepool"lltransportphasewouldbelargely completedpriortostrainersbeingplacedinservice.Response,Pg.1666.Fortheblowdowntransportevaluation,itwasnotclearhowtheDrywellDebrisTransportStudy(DDTS),NUREG/CR-6369,Dry-wellDebrisTransportStudy,Volumes1,2,and3,September1999(ADAMSAccessionNos.ML003728226,ML003726871,andML003728322,respectively),resultswereappliedtotheplantcondition.

(

Reference:

Volume3,Section2.2.17,SlowdownTransportFrac-tions,andVolume6.2,Item5.a.2(page37).Pleaseprovidethefol-lowinginformation:(a)TheDDTScautionsthatifgratingsdonotcovertheentiretrans-portpath,theymaynotbeaseeindebriscapture.For transportpathswheregratingdoesnotfullyspanthetransport pathway,pleasestateifthecapturemetricswasadjustedtoac-countforthispotential.

RequiredResponse,Pg.288(b)Pleasestateifthecalculationalmethodologyaccountfordeple-tionofdebris,asitiscapturedonupstreamobjects.Pleaseclarify iftheamountreachingthesecondandthird(etc.)objectsre"ects thedebrislostonupstreamobjects.Thiswasnotapparenttothe NRCuponinspectionoftheequationsusedtoperformthe

calculation.

RequiredResponse,Pg.288(c)Pleaseexplainwhatwasconsideredtobea90degreeturnintheplantandhowthiscomparedtothe90degreeturnsmodeledin theDDTS.PleaseexplainhowitwasdeterminedthattheDDTS resultsareapplicabletotheSTPconditionsconsideredtobe90 degreeturns.

RequiredResponse,Pg.290(d)Pleaseclarifyiftherearelimitstothemassofdebristhatcanbecapturedonstructuresoronspeci"csurfaceareasofstructures and,ifapplicable,howsuchlimitswouldthecalculations forholdup.Response,Pg.293(e)PleaseexplainhowtherangesofvaluesusedintheDDTSweredeterminedtobeapplicabletotheSTPconditions.

RequiredResponse,Pg.297Tuesday1 stMarch,2016:19:32,Page67of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION7.ForthewashdowntransportevaluationitwasnotcleartotheNRCthattheDDTStestresultswereappliedrealisticallyorconser-vativelytotheSTPplantconditionasdescribedinVolume1,Section 1.2.3,WashdownTransport,Volume3,Section2.2.18,Washdown TransportFractions,andItems5.a.3and5.a.5ofVolume6.2.Please providethefollowinginformation:(a)Pleasestateifthewashdownevaluationconsideredthatitmaybemorelikelyforapieceofdebristhathasbeenblownthroughone ormoregratingstosubsequentlywashdownthroughgratings.It appearsthattheDDTSdidnotusedebristhathadbeenpassed throughgratingswhenstudyingwashdownthroughgratings.

RequiredResponse,Pg.301(b)TheDDTSwashdowntestswererunfor30minutes.TheDDTSstatedthatmostwashdownoccurredinthe"rst15minutes.It wasnotcleartotheNRCsfromthetestresultshowwash-downoverasigni"cantlylongerperiodoftimewouldoccur.

PleaseexplainwhytheDDTSresultsareapplicabletosigni"-

cantlylongerwashdownperiods.

RequiredResponse,Pg.302(c)Pleasestateifdebrisiswasheddownthroughonelevelofgrating,ifitismorelikelytowashthroughsubsequentlevels.Ifitwashes throughmorethanonegrating,isitmorelikelytopassthrough subsequentlevels?Pleaseexplainhowthetransportevaluation accountsforsuchalikelypotential.Whatwasconsideredwhen determiningtheretentionfractionsfordebrisonadditionallevels ofgratinginthewashdowntransportevaluation?Itwasstated thatengineeringjudgmentwasusedinthisdetermination,but theNRCdidnot"ndanadequatebasisdocumentedforthe engineeringjudgment.

RequiredResponse,Pg.303(d)Pleasestateifthewashdowntransportevaluationaccountedforthesigni"cantlyhighervelocitiesthatmayoccurwithsheeting "owatthebeginningofwashdown.

RequiredResponse,Pg.303(e)Thesubmittalprovidedthecalculationsforwashdownpercent-ages.Item5.a.3(Volume6.2,page43)usesvaluesof0.4and 0.5forF wgfractionofdebrisheldupwhenwashedthroughthe"rstlevelofgrating.TheDDTSstatesthat40-50percentpassthrough.Pleaseclarifyif0.4and0.5bereversedorifthe0.4 shouldbechangedto0.6.Theterminologyusedisnotclearand canbemisunderstood.

RequiredResponse,Pg.304(f)Table2.5.24ofVolume6.2istitled,Washdowntransportfrac-tionsusedinCASAGrande,buttheleadingparagraphstates thatthetablecontainsblowdownfractions.Pleaseclarifywhether itisblowdowntransportfractionorwashdownblowdowntrans-port.RequiredResponse,Pg.3048.Theevaluationfortransportofpartiallysubmergeddebrisontheop-eratingdeckmakesseveralunsubstantiatedassumptions(Item5.a.5, Volume6.2,page54).Pleaseprovidethefollowinginformation:(a)PleaseexplainiftheassumedsizedistributionconsideredthatmostofthedebrisblowntotheoperatingdeckwouldpassthroughTuesday1 stMarch,2016:19:32,Page68of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONgratingthuslikelyreducingthesize.Pleaseclarifyiftheassumedsizedistributionwasadjustedforthis RequiredResponse,Pg.304(b)Pleasestateiftheevaluationconsideredthattheinitialsheeting"owmaybeatahighervelocitythanthesteadystate"owandthatthismaypushdebrisacrossthe"oorbeforeasteadystate occurs.RequiredResponse,Pg.305(c)Pleasestatethebasisfortheporosityequation.Pleaseexplainwhythebulkdensity(as-fabricated)ofthe"berisrelevantafterit hasbeenrenderedintosmallpiecesandthenbeenblownthrough

grating.RemovedResponse,Pg.305(d)Pleaseclarifyiftheevaluationconsideredthatairmaybetrappedwithinthe"berandthatitmaypickupadditionalairasit tumblesacrossthe"oor.RemovedResponse,Pg.305(e)Pleasestateifthereisanyexperimentaldataavailabletovalidatethecalculationalmethodology.

RequiredResponse,Pg.3059.ItwasnotcleartotheNRCifthe"brousdebriserodedfromlargeandsmallpiecesofdebriswereaddedtothe"netransportterm.

Pleaseclarifythattheerodedtermwasaddedtothe"nesourceterm andisnotaddedasthesizecategoryfromwhichtheywereeroded.For example,inFigure5.5.3ofVolume3,thetransporteddebrisshould be1.8percent"nesand35.6percentsmallwhilethetotalshows 37.4percenttransported(35.6+1.8).Pleasestateiftheevaluation includesthe1.8percentas"nedebris.

RequiredResponse,Pg.16710.Thesubmittalstatesthatunquali"edcoatingsthatfailafterthespraysaresecuredcannottransporttothecontainmentsump(Refer-enceVolume1,Section1.2.3,WashdownTransport,Volume3,Sec-tion2.2.10,Unquali"edCoatingsQuantity,Volume3,Section5.4.5, Unquali"edCoatingsDebris,Volume3,Section5.5.7,Strainer Transport).Pleaseexplainhowitwasdeterminedthattheywould nottransport.Pleaseclarifyiftherearetransportmechanismsbe-sideswashdownfromcontainmentspraythatcouldcausesomeof thecoatingstotransport.Forexample,pleaseexplainifcoatingsare locatedinareaswheretheycouldfalldirectlyintothesumporfall relativelyfreelytothesump.Explainifthe"owofcondensationon surfacescancarryparticlesoffailedcoatingstothesump,etc.(page 173,Section1.2.3;page571,Section2.2.10,page674,Section5.4.5, page680,Section5.5.7)

RequiredResponse,Pg.30511.Table5.5.5ofVolume3liststherecirculationdebristime,x(t)andstatesthatitisdescribedinSection5.8ofVolume3.TheNRC wasnotabletolocateadescriptionofthisvariable.Pleaseprovidea de"nitionofthedebrisrecirculationtime.Thefoundtheterm x(t)describedinSTPsinitialsubmittaldaredJune19,2013(page74 of174oftheattachment),whichhasbeensupersededinitsentirety.

Pleaseprovidearesponsetothefollowingquestions,whicharepar-tiallybasedontheinformationprovidedinJune19,2013,submittal.(a)PleaseprovideadescriptionoftherecirculationdebristimeasimplementedinsubmittaldatedNovember13,2013.RemovedResponse,Pg.167Tuesday1 stMarch,2016:19:32,Page69of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Pleasedescribethetypesandsizesofdebristowhichtherecir-culationdebristimeapplies.RemovedResponse,Pg.167(c)Pleasestateiftheequationassumeshomogeneousmixinginthepool.Ifso,pleaseexplainifthisthisisavalidassumptionforall debristypes.RemovedResponse,Pg.168(d)Itappearsthatthex(t)functioncalculatesthatalldebrisisatthestrainerattime=0anddecreasesastimeprogresses.Thisappears tobethereverseoftheactualconditionexpected.Pleaseexplain.RemovedResponse,Pg.168(e)Pleaseexplainthebasisforthedepletionrate.RemovedResponse,Pg.16812.BasedondescriptionofItem5.a.4ofVolume6.2(Page47),itisassumedthatdebriswillremaininthevicinityinwhichitwaswashed downuntilrecirculationstarts.Pleaseprovideadditionaljusti"cation forthisassumption.Pleasestateifthedebriswouldberedistributed duringpool"llincludingbypotentialsheeting"owandifthiswould theassumptionthatdebrisismixedhomogeneouslyinthepool atthestartofrecirculation.Ifso,pleasedescribewhichtypesand sizesofdebrisareRemovedResponse,Pg.21113.Table2.5.32ofVolume6.2includesvaluesforsmallpiecesofMi-crotherm.Thisisinconsistentwithotherstatementsinthesubmittal thatMicrothermisassumedtofailas100percent"nes.Pleaseclarify ifallMicrothermpiecesfailas"nes.Pleasestatehowsmallpiecesof MicrothermaretreatedinSTPsevaluation.RemovedResponse,Pg.169

• HeadLossandChemicalBumpUp14.TheSTPNOCsubmittalassumesthatnochemicalbumpupoccursifthedebrisbedthicknessislessthan1/16-inch(

Reference:

Volume 1,Section1.1,Step14;Volume3,Assumption7.c;Volume6.2,Items 5.a.10and5.a.11).TheNRChaspreviouslyconcludedthata 1/16-inchdebrisbedisanadequatemetricforthispurposeforclean plants,wheretheworstanalyzedbreakcouldresultin1/16-inchof "berwhenconservativemethodswereusedforestimatingtheamount ofdebrisgeneratedandtransportedtothestrainer.Thecleanplant criteriaalsoincludedotherrestrictionsfortheuseofthemetric,such asthelackofproblematicdebriswithinanyZOI.Thehasnot determinedthatthislimitisappropriateforamorerealisticrisk-informedevaluation.Thehasreviewedtestresultsconducted withabout1/16-inchof"brousdebristhatresultedinsomehead losswhenchemicalprecipitateswereaddedtothetest.Italsoappears thattheSTPevaluationhasnotconsideredallaspectsoftheclean plantcriteria.Whetherornotthecleanplantcriteriaarethebasis forthe1/16-inchlimit,pleaseprovideajusti"cationforitsuse.RemovedResponse,Pg.30615.TheSTPNOCsubmittalstatesthatthestrainerdebrisheadlossiscalculatedusingacorrelation(

References:

Volume3,Section5.6.2, ConventionalDebrisHeadLossModel,Volume3,Assumption7.e; Volume1,Section1.1,StructuredInformationProcessFlow.)The NRChasgenerallynotacceptedcorrelationsforthequali"cationTuesday1 stMarch,2016:19:32,Page70of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONofPWRstrainersforseveralreasons.Pleaseexplainwhythefollowinggeneralconcernswiththeuseofcorrelationsarenotanissueforthe STPapplication:(a)Correlationshavenotbeenvalidatedforthefullrangeofdebrisloadsandmorphologiespresentunderplantconditions.RemovedResponse,Pg.71(b)Correlationsdonotaddressnon-homogeneousdebrisbedswhichareverylikelytooccurduetotransporttimingandnon-homo-geneous"lteringofdebriswithinthebed.RemovedResponse,Pg.307(c)Correlationshavenotbeenvalidatedforthefullrangeofpotential"owconditionsandstrainergeometriesthatarepresentinplants.RemovedResponse,Pg.307(d)Thereissigni"cantuncertaintyinthemodelparametersusedtodescribethephysicalattributesofthedebrisbedconstituents.RemovedResponse,Pg.30916.TestingperformedtovalidatetheNUREG/CR-6224 1correlationforspeci"cSTPconditionsdoesnotappeartoaccomplishthepurpose

(

References:

Volume3,Section5.6.2,"ConventionalDebrisHeadLoss Model,"andVolume6.2,Item5.a.10).Additionally,theNRC doesnothavecompleteinformationtoconcludethatthetestingad-equatelyrepresentedtheplantcon"gurationandrangeofconditions thatcouldoccuratSTPfollowingaLOCA.Therefore,thewas unabletodeterminethattheplantspeci"cverticallooptestsresults wererepresentativeofheadlossesthatcouldoccurfromadebrisbed onaprototypicalmodule.Thecorrelationresultsandthesinglever-ticallooptestresultthatmodeledtheJuly2008Alden"umetest underSTPspeci"cconditionsweresigni"cantlytfromeach other,andfromtheresultsofthe"umetest.Thatis,allthreeresults, althoughmodelingsimilarconditions,hadsigni"cantlytre-sults.Thesubmittalexplainedastowhytheresultsweresubstantially t,buttheexplanationwasnotcon"rmedbytestingorbyuse ofacceptedtheories.Industryheadlosstestsusingsimilarsurrogates onprototypicalstrainermodulesresultedinsigni"cantlyhigherhead lossesthanthosereportedbySTPfortheirverticallooptestingand thosecalculatedbyuseofthecorrelation.Theisconcernedthat verticallooptestandmoduletestresultsfromtestsconductedun-dersimilarconditionsmayduetothedbetweendebris characteristicsinverticallooptestandmoduletestdebrisbeds.These couldbecausedbydintransportanddeposition ofthedebrisontotheperforatedsurfaces.Therefore,theiscon-cernedthatthevalidationtestingisnotrepresentativeoftheplant.

Pleaseprovidethefollowingadditionalinformation:(a)IftheverticallooptestsconductedbySTPareimportanttotheconclusions,pleaseprovidedetailsastowhytheSTPverticalloop testsarevalidconsideringthatothermoduletestsconductedin severaltfacilitiesundersimilarconditions,debrisloads, anddebrischaracteristicshadsigni"cantlytresults.RemovedResponse,Pg.310 1NUREG/CR-6224,ParametricStudyofthePotentialforBWRECCSStrainerBlock-ageDuetoLOCAGeneratedDebris,"FinalReport,October1995(ADAMSAccessionNo.

ML083290498).Tuesday1 stMarch,2016:19:32,Page71of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)IftheverticallooptestsconductedbySTPareimportanttotheconclusions,pleaseprovideevidencethatverticallooptests conductedundersitespeci"cconditionswillcorrelateto"ume testsconductedundersimilarconditionsortoheadlossesthat wouldoccurintheplant.Pleaseincludeinformationregarding howitwasdeterminedthatthedebristhattransportedtothe horizontalstrainersurfaceresultedinadebrisbedofsimilarchar-acteristicsandmorphologytothatwhichwouldtransporttothe plantstrainer.Pleasestatehowwasitdeterminedthatthehead losseswouldbecomparable.RemovedResponse,Pg.311(c)Pleaseprovideinformationthatdemonstratesthatthecorrela-tionusedbySTPisvalidforplantspeci"cstrainergeometries andplantspeci"cconditions.Alternately,pleaseprovideabasis forusingacorrelationthathasnotbeenvalidatedspeci"callyfor STPplantconditionsandgeometries.RemovedResponse,Pg.312(d)PleasediscusshowtheNUREG/CR-6224correlationcouldbeusedtopredicttheheadlossesthatwouldbeexpectedunder conditionssimilartothoseinthetwo"umetestsconductedby STPinFebruaryandJuly2008.RemovedResponse,Pg.31217.ThesubmittalstatesthatalltestingperformedtovalidatetheNUREG/CR-6224correlationwasboundedbycorrelationpredictions(

References:

Volume1,Section1.2.7,ConventionalHeadLossModel,andVol-ume3,Section5.6.2,ConventionalDebrisHeadLossModel).There havebeennumerouscaseswherethecorrelationseverelyunder-predicted headlossesthatwerecarriedoutundercarefullycontrolledcon-ditions.NUREG-1862,DevelopmentofPressureDropCalculation MethodforDebris-CoveredSumpScreensinSupportofGenericSafety Issue191,February2007(ADAMSAccessionNo.ML071520440),

andNUREG/CR-6917,ExperimentalMeasurementofPressureDrop AcrossSumpScreenDebrisBedsinSupportofGenericSafetyIssue 191,February2007(ADAMSAccessionNo.ML071910180),con-taindatathatshowthattheNUREG/CR-6224correlationisnot conservativeinallcases.TheseNUREGsdeterminedthatcorrelation predictionsarehighlydependentontheparametersusedtodescribe thephysicalattributesofthedebrisbedconstituentsandthatthese parametershavesigni"cantuncertainty.TheseNUREGsalsodeter-minedthatheadlossesarenotwellpredictedbyacorrelationthat assumesahomogenousdebrisbed.Someoftheexperimentaldata involved"nedebris,microporousdebris,non-homogeneousbeds,and otherconditionsthattheNUREG/CR-6224correlationisnotde-signedtoaccountfor.Itisverylikelythatsomeconditionsthat NUREG/CR-6224correlationdoesnotaccountfor,maybepresent underplantpost-LOCAconditions.Thesubmittalstatesthatthe headlosscorrelationfromNUREG/CR-6224hasbeenextensively validatedforvariousconditions.TheNRCisoftheopinionthat thereislittleornotestingthathasbeenconductedundercondi-tionssimilartothoseatSTP.Theisconcernedwiththevali-Tuesday1 stMarch,2016:19:32,Page72of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONdationissueslistedbelowwhenusingacorrelationforquali"cationofstrainers.PleasestatehowtheSTPevaluationaccountsforthese uncertaintiesandlackofvalidationofthecorrelationunderplant

conditions.(a)Debrisconstituentsinvalidationtestingarenotplant-speci"cRemovedResponse,Pg.313(b)Debrissizesinvalidationtestingarenotplant-speci"c.RemovedResponse,Pg.314(c)VerylittlevalidationtestingwasconductedatSTPvelocitiesandnonevalidatedthecorrelation.RemovedResponse,Pg.314(d)Validationtestingdidnotincludeprototypicalstrainergeome-tries.RemovedResponse,Pg.314(e)Validationtestingperformedinverticalloopsdoesnotsimulatepotentiallyimportantaspectsofdebrisbedformationunderplant

conditionsRemovedResponse,Pg.314(f)Therecordsofearlyvalidationtestingarenotavailableordonotcontaintheinformationrequiredtodeterminewhetherthe testswereconductedtoadequatelyrepresentplantconditions.

Therefore,conclusionsfromearlytestingmustbelimited.RemovedResponse,Pg.31518.TheimplementationofthecorrelationintheSTPmodelmakesspe-ci"cassumptionsandmaypotentiallycontainmodelingerrorsthat cansigni"cantlytheresultsofthecalculation(

References:

Vol-ume3,Assumptions7.b,7.e,and7.f;Volume3,Section5.6.2,Con-ventionalDebrisHeadLossModel;Volume6.2,Item5.a.10;and Enclosure6,Table1).Pleaseprovidethefollowinginformationto justifythattheassumptionsanduseofthecorrelationisrealisticor conservativeforSTPplant-speci"cconditions.(a)Pleaseprovidejusti"cationthatthebedsarehomogeneousrep-resentativeoftheplant(Volume3,Assumption7.eandVolume 6.2,Item5.a.10).RemovedResponse,Pg.315(b)Itisassumedthat"berglassdebriswouldaccumulateuniformlywithadensityof2.4poundspercubicfoot(lb/ft3).TheNRC isoftheopinionthatassumingthedebrisbeddensitytobe thesameasthemanufactureddensitymaynotbeanaccurate assumptionandisbasedontheobservationofdebrisbedsformed inindustrytestsandNUREG-1862testing.TheNRCisfur-theroftheopinionthatintheplant,only"neandsmall"berwill transportandcollectatamuchhigherdensity.Pleasedescribe whythedensityassumptionisvalidandwhyitdoesnotsig-ni"cantlytheresults.Alternately,re-performtheanalysis withadensitythathasbeenshowntobeappropriate.(Volume 3,Assumption7.fandSection5.6.2andVolume6.2,Item5.a.1

0).RemovedResponse,Pg.315(c)PleaseexplainhowtheNUREG/CR-6224correlationcompres-sionfunctionisappliedintheSTPmodel.NUREG-1862found thatthecompressionrelationfromNUREG/CR-6224doesnot accuratelymodelthecompressionofthebed,especiallyatlow "owvelocitieslikethoseatSTP.(Volume3,Section5.6.2).RemovedResponse,Pg.316Tuesday1 stMarch,2016:19:32,Page73of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)ThesubmittalstatesthatSTPimplementedalinearmassweightedaverageinsteadofthevolumetricweightedaverageforimple-mentationofcompositesurfacetovolumeratio(S v)inthe6224correlation.Thesubmittalstatesthattherearemanypossible compositeweightingmethodsthatcouldbeused,butdoesnot justifythemethodchosenintheapplication.NEI04-07and NUREG/CR-6371,Blockage2.5ReferenceManual,Decem-ber1996(notpubliclyavailable),bothrecommendedthevolume weightingmethod.Pleaseexplainwhymassweightingisaccept-able.Pleaseexplainifboththemethodsresultinsigni"cantly tresults.(Volume3,Section5.6.2andEnclosure6).RemovedResponse,Pg.317(e)PleaseprovideatechnicalbasisforAssumption7.bregardingcoatingmaterialpackingfractions.Pleasediscusstheof theassumptiononresults.Pleaseprovidethepotentialrangesof packingfactorsforcoatingmaterials.(Volume3,Assumption7.b andVolume6.2,Item5.a.10).RemovedResponse,Pg.31719.Theapplicationofamultiplierof"ve(5x)totheresultoftheheadlosscorrelationusedintheSTPmodelappearstoindicateuncer-taintyintheabilityofthecorrelationtopredictheadlossescorrectly

(

References:

Volume1,Section1.2.7andVolume3,Section5.6.2).

IftheNUREG/CR-6224correlationisarobustmodelasimpliedin thesubmittal,theNRCisoftheopinionthatitisunnecessary tousesafetyfactorsintheheadlosscalculationsforachievingreal-isticresults.ThenotedthatsomePNNLtestingshowedthat the6224correlationunderpredictedheadlossbymorethanafactor of5X.Pleaseprovidejusti"cationforapplyingthemultipliertothe resultsoftheheadlosscorrelation.RemovedResponse,Pg.31720.Thesubmittalassumesthatpaintchipsorotherrelativelylargedebristhatmayreachthestrainercanbeaccountedforinthecorrelationas sphericalparticles(

Reference:

Volume3,Section5.6.2).Largedebris mayfullyorpartiallyblockstrainerperforationsandmaydeposit non-homogeneouslyonthestrainer.Pleaseprovideanexperimental basistocon"rmthatpaintchips(orotherlargeparticles)maybe accuratelymodeledinthecorrelation,includingtheassumptionthat theycanbeaccuratelymodeledassphericalparticles.Intheabsence ofanexperimentaljusti"cation,pleaseprovideanalternatebasisfor theSTPtreatmentofpaintchipsandotherlargeparticlesintheheadlosscorrelation.RemovedResponse,Pg.31821.TheSTPcorrelationusesphysicalpropertiesofmaterialspredictedtobeinthedebrisbedinordertocalculateaheadloss(

References:

Volume3,Section5.6.2,ConventionalDebrisHeadLossModel, andVolume6.2,Item5.a.10).ResultsfromtheNUREG/CR-6224 correlationareheavilydependentupontheaccuraterepresentation ofmaterialphysicalproperties.Oneofthemostparameters toaccuratelydetermineisthesurfacetovolumeratio(S v).Pleaseprovidethefollowinginformation:(a)PleasestatehowS vvaluesweredeterminedforeachmaterial.RemovedResponse,Pg.319Tuesday1 stMarch,2016:19:32,Page74of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)Itisknownthatforsomedebristypes,andpossiblyalldebristypesexpectedtobepresentinPWRdebrisbeds,physicalmea-surementscannotprovideS vvaluesthatallowaccuratepredic-tionofheadlossinexistingcorrelations.Thiswasespeciallyev-identformicroporoustypematerialsandwasshowntobetrue forothermaterialsbyNUREG-1862.Pleaseexplainthebases fortheS vvaluesandothermaterialpropertiesusedintheSTPimplementationofthecorrelation.RemovedResponse,Pg.319(c)Pleasestatehowtheuncertainty,describedonpage184ofVol-ume3,iscausedbytherelationshipbetweenexperimentallyde-ducedS vvaluesandheadloss,accountedforintheSTPmodel.RemovedResponse,Pg.319(d)TheNRCdoesnotagreewiththestatement,onpage185ofVolume3,whichstatesthatthelackofagreementbetween thecorrelationandtestresultsusinggreensiliconcarbideand tindonottheSTPcalculations.ItappearsthatSTPhad ydeterminingparameterstoinputtothecorrelationto attainaccurateresults.Pleaseprovidebasisfortheconclusion thatthelackofagreementbetweenthecorrelationresultsand testresultsdonotSTPheadlosscalculations.RemovedResponse,Pg.32022.TheNUREG/CR-6224correlation,andothersimilarcorrelations,usespeci"csurfaceareas(S v)forcylindricalobjectsassumingthatthe"berisorientedperpendiculartothe"owandthatthe"bershavea uniformdiameter.ThisassumptionisusedintheSTPmodel(Refer-ence:Volume1,Section1.2.7,ConventionalHeadLossModel,and Volume3,Section5.6.2,ConventionalDebrisHeadLossModel).

NUREG-1862calculateddtspeci"csurfaceareasforvarying diametersofNukonandnotedainS vbetween"bersthathadbinderandthosethatdidnot.TheNUREGalsoestimatedthe

S vofNukon"bertobearound250,000to300,000ft 1insteadof 180,000ft1whencorrectedfortestdata.(STPusesfortheS v of 571,429m1 (174,172ft 1)forNukon"ber.)PleaseexplainhowtheSTPevaluationtakesthese"ndingsintoaccount.(Volume3,Section

5.6.2).RemovedResponse,Pg.32023.TheSTPNOCsubmittalmakestheassumptionthatMicrotherm"berswillhavepropertiessimilartothoseofNukon(bulkdensity=2

.4lbm ft 3 ,microscopicdensity=165 lm ft 3andS v=666 , 667 m1)(

Reference:

Vol-ume3,Section5.6.2).Pleasestatethebasisforthisassumption.Also,pleasejustifytheuseoftheNukon"berbulkdensityasthedebris beddensity.RemovedResponse,Pg.32124.Thephysicalcharacteristicsusedintheheadlosscorrelationcanhaveasigni"cantontheresultsoftheheadlosscalculations.Char-acteristicvaluesthatdescribetheassumedbehaviorofSTPdebris areprovidedinTables5.6.1and5.6.2ofVolume3.NRCresearch conductedforNUREG-1862hasdeterminedthatsomeofthevalues thatdescribethephysicalcharacteristicsofdebrisarenotwellun-derstood.PleaseprovidethebasesforthevaluesinTables5.6.1and 5.6.2.PleaseprovidereasonableuncertaintybandsforthematerialTuesday1 stMarch,2016:19:32,Page75of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONproperties.Also,pleaseexplainhowcompoundedinaccuraciesinas-sumedmaterialpropertieswouldtheheadlossvaluespredicted bythecorrelation.RemovedResponse,Pg.32125.Volume3,Assumption7.f,statesthatitisassumedthat"berglasswillaccumulateuniformlyonthestrainersbutalsostatesthatthe amountofdebristhatcancollectonthebottomofthestraineris limitedtotwoinches.Thisassumptionseemstocontradictitself.(a)Pleaseexplainhowtheassumptionisaccountedforinheadlosscalculationsorprovideinformationthatshowsitisnotsigni"cant totheresults.Pleaseexplainhowanon-uniformaccumulationof "brousdebris,limitedbythe"oororpoolheight,would theheadlosscalculation.RemovedResponse,Pg.211(b)PleaseprovideanevaluationofhowthisAssumption7.e.ofVolume3regardinghomogeneousbedformation.RemovedResponse,Pg.21226.Thesubmittalcalculatescircumscribedbedsurfaceareasbasedondebrisloading(

Reference:

Volume3,Section5.6.2).Pleaseprovide thefollowinginformation:(a)Pleasestateifareascalculatedforbedstransitionedfromthinbedtocircumscribed.RemovedResponse,Pg.212(b)When"brousdebrisisdepositedonthestraineritsdensitywillbesigni"cantlyincreasedfromthemanufacturedvalue.Please statehowwasthisaccountedfor(Volume3,Page696,Section

5.6.2).RemovedResponse,Pg.212(c)Pleaseclarifyifthereareanyobjectsaroundthestrainerthatwouldpreventthedebrisbedfromaccumulatinguniformlyas assumedinthestrainerloading(Volume3,Table5.6.3).

RequiredResponse,Pg.212(d)TheNRCisoftheopinionthatitisnotrealistictoassumethethicknessofthedebrisbedonthestrainercanbesuchthat itwillexceedtheheightofthewaterlevelinthepool.Please explainhowthisthedebrisloadingcalculation(Volume 2,Section5.6.2).RemovedResponse,Pg.213(e)Pleasestatehowoftenthedebrisloadingalgorithmresultsinacircumscribedbedoronethatistransitioningtocircumscribed (fullyorpartially"lledinterstitialvolume).RemovedResponse,Pg.215(f)Pleaseexplainthesigni"canceofcasesthatresultintheintersti-tialvolumeofthestrainerbecomingpartiallyorcompletely"lled withdebris.RemovedResponse,Pg.21727.Thesubmittalstatesthatthecleanstrainerheadloss(CSHL)is0.220ft.basedonatest(

Reference:

Volume3,Sections2.2.23,Clean StrainerHeadLoss,and5.6.1,CleanStrainerHeadLoss).Itap-pearsthatthevaluewastakenfromatestthatwasconductedus-ingasinglemodule.TheCSHLshouldbere"ectiveoftheentire strainerincludingallmodulesandconnectingpiping,"ttings,etc.IntheSTPNOCletterdatedDecember11,2008(ADAMSAccessionNo.

ML083520326),theCSHLwasstatedtobe1.95ft.PleaseexplainwhyTuesday1 stMarch,2016:19:32,Page76of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthevalueprovidedintherisk-informedsubmittalissigni"cantlydif-ferentfromthepreviouslycalculatedvalueandverifythatitincludes allheadlossesassociatedwiththeentirecleanstrainertrain.

RequiredResponse,Pg.32328.Consideringtheindividualuncertaintiesthatresultfromtheissuesdescribedintherequestforadditionalinformationonthesubjectof headloss,pleaseprovidejusti"cationthattheuseofacorrelationis acceptableintherisk-informedmodel.Alongwiththejusti"cation, pleaseprovideananalysisoftheoveralluncertaintyandstatehow thiswillbeincorporatedintotheoverallrisk-informedevaluation.RemovedResponse,Pg.323

• NPSHandDegasi"cation29.Volume1,Section1.1,StructuredInformationProcessFlow,andVolume3,Sections2.2.28,PumpGasLimits,and5.7.4,Accep-tanceCriterion:PumpGasVoidLimits,describethemethodology forcalculatingNPSHmargin.Thesubmittalstatesthatifthevoid fractionexceeds2percentthatthescenarioisrecordedasafailure.

ItisnotclearthatNPSHRequired(NPSHR)iscorrectedforde-gasi"cationthatmayoccuras"uidpassesthroughthedebrisbedas recommendedbyRG1.82,Revision4,WaterSourcesforLongTerm RecirculationCoolingFollowingaLoss-of-CoolantAccident,Revi-sion4,March2012(ADAMSAccessionNo.ML111330278).Please clarifywhetherNPSHRiscorrectedforthevoidfractionatthepump inlet.IftheNPSHRisnotcorrectedforthevoidfraction,pleasepro-videajusti"cation.

RequiredResponse,Pg.17730.TheSTPNOCsubmittalstatesthatthedegasi"cationcausedbythepressuredropthroughthedebrisbediscalculatedtodetermineif apumpfailurecriterionismet(

References:

Volume1,Section1.1, StructuredInformationProcessFlow;Volume3,Assumptions8a.

throughi.;Volume3,Section5.7.2,Degasi"cation;andEnclosure 6,Table1).Pleasestateifthedegasi"cationcalculationcreditscon-tainmentaccidentpressure.Ifso,pleaseexplainhowthepressurefor eachcaseorconditioniscalculated.Pleasestatewhattemperatureis usedforthedegasi"cationcalculationandhowthistemperaturewas calculatedforeachcase.

RequiredResponse,Pg.21731.TheSTPNOCsubmittaldoesnotseemtoevaluatethepossibleofthecollectionofgasbubblesinthestrainerorECCSpumpsuction piping(

Reference:

Volume3,Assumption8.h.andSection5.7.3,Gas TransportandAccumulation).Pleaseexplainhowitwasdetermined thatgasbubbleswouldnotcollectinthestrainer,orpipingbetween thestrainerandECCSandCSSpumpsandeventuallytransportas largevoids.Ifgaspocketscanbecometrappedintheselocations, pleaseexplainits RequiredResponse,Pg.21732.TheNRCcouldnotdeterminewhetherthecalculationofNPSHAvailable(NPSHA)includescontainmentpressuregreaterthanthe saturationpressureofthesump"uid.Volume3,Assumption1.cin-dicatesthatcontainmentpressuregreaterthanthesaturation(aboveTuesday1 stMarch,2016:19:32,Page77of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION14.7poundspersquareinchabsolute(psia))isnotcreditedintheNPSHcalculations(

Reference:

Volume1,Section1.1,Structured InformationProcessFlow;Volume3,Sections3,Assumptions, and5.7.2,"Degasi"cation";andEnclosure6,Table1).Pleaseclarify ifthecalculationforNPSHAincludescontainmentpressureabove thesaturationpressureofthe"uid.Ifcontainmentpressuregreater thanthesaturationpressureofthe"uidiscreditedintheNPSHA calculation,pleaseprovidejusti"cationforitsuseandprovidethe methodologyusedtocalculatethecontainmentpressureandsump "uidtemperatureforeachcase.

RequiredResponse,Pg.21733.ThepoolwaterlevelcalculationprovidedintheSTPNOCsubmittaldoesnotappeartoaccountforchangesinpoolareawithelevation orchangesinobjectsthatmaydisplacewater(

Reference:

Volume3, Section2.2.5,"PoolWaterLevel").Pleasestateiftherearesigni"cant changesinareaorobjectsinthepoolthatcouldwaterlevel.If so,pleasedemonstratethatthemethodologyusedtocalculatepool levelisrealisticorconservative.

RequiredResponse,Pg.32434.Thesubmittallistsminimumandmaximumvaluesforcontainmentspray"owrates(

Reference:

Volume3,Section2.2.8,ECCSandCCS FlowRates).Pleasestatehowthesevaluesareusedintheevaluation.

If"owratesotherthanthemaximumareused,pleaseexplainhow theappropriate"owratewasdeterminedforeachcase.Required(strnr.pen.)Response,Pg.21835.TheSTPNOCsubmittalcalculatesanequivalentbreaksizeof38.9inchesfora27.5inch-DEGBinVolume3,Section2.2.8.Pleasede-scribehowtheequivalentbreaksizeof38.9incheswascalculatedand whyitwasnecessarytocalculatethisvalue.RemovedResponse,Pg.21836.ThesubmittalstatesthattheNPSHRfortheECCSandCSSpumpsis12ft(

Reference:

Volume3,Section2.2.24,"PumpNPSHMargin,"

andEnclosure6,Table1).TheproposedUFSARrevisions(pages9 and11ofAttachment2toEnclosure3)statethattheNPSHRforthe pumpsisbetween16.1and16.5ft.ApreviousSTPNOCsubmittal datedDecember11,2008(ADAMSAccessionNo.ML083520326),

forresponsetoGenericLetter(GL)2004-02statedthattheNPSHR valuesfortheLHSI,HHSI,andCSpumpsare16.5ft.,16.1ft.,and 16.4ft.,respectively.PleaseprovidethebasisfortheNPSHRvalues usedinthecurrentevaluation.

RequiredResponse,Pg.325

• In-VesselandBoricAcidPrecipitation37.TheSTPNOCsubmittaluses7.5gramsperfuelassemblyasthe"beracceptancelimitforcold-legbreaks(

References:

Volume1,Section 1.1,StructuredInformationProcessFlow,Step18;Volume1,Sec-tions1.2.10,BoricAcidPrecipitation,and1.2.11,In-VesselFiber Limits;Volume3,Assumption11.b;Volume3,Section4.2,Struc-turedInformationProcessFlow,Step18;Volume3,Section5.11.2, AcceptanceCriteria:DebrisLoads;andVolume6.2,Items5.a.13 and5.a.15).TheNRCstatedinitsSEon"EvaluationofLong-TermCoolingConsideringParticulate,Fibrous,andWCAP-16793,Tuesday1 stMarch,2016:19:32,Page78of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRevision2,"ChemicalDebrisintheRecirculationFluid,"October2011(ADAMSAccessionNo.ML13084A154),thatthemaximum amountof"berthatwouldbepresentinthelimitingreactordesign followingacold-legbreakwouldbeexpectedtobeabout7.5grams, ifthehot-legbreak"beramountdidnotexceed15grams.The didnotconcludethata"berloadof7.5gramswasadequatetoen-surethatboricacidprecipitationwouldnotoccur.Theamountwas projectedasthepotentialmaximumintheshorttermuntilindustry completedaseparateprogramonboricacidprecipitation(BAP).In itsevaluation,theconsideredthattheplantcalculationofthe in-vesseldebrisloadincludedtheworstcasedebrisloadfortheplant andthatmostplantswouldhavemuchlessthan7.5gramsofde-brisfollowingacold-legbreak.NotethattestingfortheWCAPdid showthatthe"owrequiredtomatchdecayheatboilwouldreach thecorefollowingacold-legbreakwithdebrisloadsgreaterthan7.5 grams,butdidnotshowthatmixingcreditedtopreventBAPwould notbeThelimitof7.5gramsperfuelassemblyhasnotbeen technicallyjusti"edasanacceptancecriterionforBAP.Pleasepro-videthetechnicalbasisforassumingthat7.5gramsisanacceptable limitforacold-legbreakatSTPwhenconsideringthepotentialfor boricacidprecipitation.

RequiredResponse,Pg.218

• DebrisBypass38.Thesubmittaldiscussesthefractionofdebristhatis"sheddable"fromadebrisbed(

Reference:

Volume3,Section5.8,"DebrisPenetration").

PleaseexplainifVn,(Fractionofdebristhatissheddable),isa simplefractionoritisdependentontheamountofdebrisinthebed.

RequiredResponse,Pg.32739.ThesubmittalstatesthatdebrisbypassorpenetrationtestingwascompletedtosupportmodelingofthebypassofdebrispasttheSTP strainer(

Reference:

Volume6.2,Item5.a.16).Pleaseprovideaddi-tionaldetailsonhowdebrispenetrationtestingfor"berwascon-ducted.Speci"cally,pleaseprovidethefollowinginformation:(a)Providedetailsonthecharacteristicsofthe"berthatwasaddedtothetestfacility.i.Howthe"berwasprepared.ii.Statewhatthepercentageswereofeach"berclassi"cationasdescribedinNUREG/CR-6808,"KnowledgeBaseforthe ofDebrisonPressurizedWaterReactorEmergency CoreCoolingSumpPerformance,"February2003(ADAMS AccessionNo.ML030780733),Table3-2afterthe"berwas

prepared.iii.Howwasitensuredthatagglomerationofthe"berdidnotoccurpriortoadditiontothetestloop?

RequiredResponse,Pg.219(b)Forteststhathadmorethanonebatchof"beraddedtothetest,pleasestatewhatthetimingwasofeachdebrisaddition.

RequiredResponse,Pg.221(c)Pleasedescribethedesignofthetestfacility.

RequiredResponse,Pg.221Tuesday1 stMarch,2016:19:32,Page79of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Wasthecirculationof"uidwithinthetankturbulent?Diddebrissettle?Ifsomedebrisdidnotreachthestrainer,howwasthis accountedfor?

RequiredResponse,Pg.222(e)Howwasitensuredthat"berdidnotbypassthe"ltersduringthetest?RequiredResponse,Pg.222(f)Wasthedesignofthestrainerandthedesignofthetestfacility("owrate,etc.)prototypicalwithrespecttotheSTPstrainer?

RequiredResponse,Pg.222

• DefenseInDepthandMitigativeMeasures40.Volume1,Section2.1.1,Defense-in-Depth,statesthattheconcernsraisedinGSI-191havenobearingoncontainmentintegrityoron thereleaseofradiation(page18ofVolume1).Volume1,Appendix C,pageC6statesthattheindependenceofbarriersisnotdegraded.

TheNRCnotesthatbarrierindependenceisafunctionofmulti-plefactors(e.g.,plantoperations,maintenance,environmentalcondi-tions)thatarenotnecessarilylinkeddirectlytoSSEdesign.Appendix Cpresentsasimilarargumentwithrespecttomaintainingabalance amongcoredamageprevention,containment,andconsequencemiti-gation.ItisnotcleartotheNRCthatalackofdesign/equipment changescanbeequatedunconditionallywithabalancedapproachto prevention,containment,andmitigation.Thepresenceofdebrismay impacttheenessofcoredamagepreventionandcontainment simultaneously.Implementationofadeterministicsolutionwouldre-sultinzeropredictedfailuresofthefuelorcontainmentasaresult ofdebris,followinganassumedfailureoftheRCSbarrier.STPs risk-informedsolutionpredictsthatsomefuelorcontainmentfailures mayoccur.Thisimpliesthattheindependenceofbarriersmaybede-gradedundertherisk-informedapproach.ConsistentwithRG1.174, pleaseprovidediscussionondefenseindepthcontainedinAppendix C,usingquantitativeassessmentstotheextentpracticable(tosup-plementtheexistingqualitativeassessment),todemonstratethatthe elementsofdefenseindepthdescribedbyRG1.174aremet.Where appropriate,provideacomparisonbetweenthehypotheticalclean plantandtheas-built,as-operatedplant.ConsistentwiththeRG, pleasealsoincludeanevaluationoftheproposedchangeon equipmentfunctionality,reliability,andavailability.

RequiredResponse,Pg.32741.Volume1,AppendixC,SectionC.5.4,listsmitigativemeasuresthatcanbetakenifthestrainerbecomesblocked.Itisnotclearhowthe mitigativemeasuresidenti"edtoaddressstrainerblockageareimple-mentedatSTP(notethattheseactionsarealsocreditedforpreven-tionofinadequatecore"ow).Pleaseexplainthefollowingtoexplain howthemitigativemeasuresarecapableofprovidingalternate"ow totherequiredequipment.(a)Themitigativeactionsidenti"edtoreduce"owthroughthestrain-ersappeartoactuallybedesignedtoconserveRWSTvolume.

Thesemeasuresmaydelaytheinitiationofrecirculation,but exceptforsecuringCSSpumpswillnotreduce"owthroughTuesday1 stMarch,2016:19:32,Page80of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthestrainer.Pleasestateatwhatpointintherecoverytheseactionsareperformed.Ifnotperformedimmediately,willthe RWSTinventorybeconserved?Ifthereductionsof"owthrough thestrainerdonotoccuruntilafterstrainerblockageisevident, pleasestateiftheseactionsaree.

RequiredResponse,Pg.223(b)PleasestateifSTPhasimplementedoperatingprocedurestosecurethethirdtrainofECCS/CSSifallthreeareinitiatedfol-lowingaLOCA.

RequiredResponse,Pg.224(c)PleaseclarifyifSTPimplementedoperatingproceduresorotherguidancetobackwashthestrainers,ifnecessary.Ifso,please providedetailsontheproceduralcontrolsforthisaction.

RequiredResponse,Pg.224(d)PleasestatewhentheRWSTre"llisstartedandhowlongittakestore"llRWSTtothepointwhereinjectionfromthetank isviable.Pleasenotethatifthetankisnotreadyforinjection whenblockageoccurs,thisactionmaynotbee.TheNRC notesthattheSTPNOCsubmittalstatesthatmoststrainer blockageeventsoccurwithinthe"rst24hoursoftheLOCA recovery.RequiredResponse,Pg.22442.Volume1,AppendixC,SectionC.5.8,MitigationofInadequateRe-actorCoreFlow,listsmitigativemeasuresthatcanbetakenifthe "owtothecoreisnotadequatetoensurecorecooling.Itisnotclear totheNRChowthemitigativemeasuresforinadequatereac-torcore"owwillbee.Mostoftheactionsattempttoinject coolantthroughthe"owpaththathasalreadybeenidenti"edaspo-tentiallyblocked.Otheractionsdonotappeartobeeifthe coreinletisblocked.Pleaseprovideadditionalinformationshowing thatthemitigativemeasuresarecapableofprovidingcoolanttothe

core.RequiredResponse,Pg.3291.3.10STSB:TechnicalSpeci"cationsBranch1.TheproposedLARprovidesassumptionsofpartial"owreductionofcer-tainECCSequipmentduringDBAevents.Pleaseexplainhowthepro-posedLARECCS"owassumptionsarewhentheCon"guration RiskManagementProgram(CRMP)TechnicalSpeci"cation(TS)Com-pletionTimesareappliedtoTSinoperableECCSSSCs.Includeinyour discussion,howtherelatedECCSequipmentPRAfunctionality(asde-

"nedinNEI06-09,Revision0,Risk-InformedTechnicalSpeci"cations Initiative4b,Risk-ManagedTechnicalSpeci"cations(RMTS)Guidelines, November2006(ADAMSAccessionNo.ML12286A322))isincludedinthe analysisandhowtheanalysisassumptionsareprogrammaticallyincluded theCRMP.RequiredResponse,Pg.1772.TheSTPCRMPcouldallowcontinuedpoweroperationwithalossofaTSsafetyfunctionforupto30days.PleaseexplainhowaTSlossoffunction, butPRAfunctional(asde"nedbyNEI06-09,Revision0)ECCSSSGis addressedintheanalysis.

RequiredResponse,Pg.178Tuesday1 stMarch,2016:19:32,Page81of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION3.Pleaseexplainhowtheassumptionsandanalysisfor"brousmaterialim-pactonECCS"owareveri"edandmaintainedprogrammatically(i.e.,

howandatwhatfrequencyareanyphysicalormaterialchangestothe analyzedimpactzonesevaluatedandwhatphysicalormaterialchanges wouldinitiateareevaluationoftheimpactzone).

RequiredResponse,Pg.179Tuesday1 stMarch,2016:19:32,Page82of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.4Round2RAIs1.4.1APLA:ProbabilisticRiskAssessment(PRA)LicensingBranch (APLA)*ProjectQualityAssuranceRegulatoryGuide(RG)1.174,Revision2,AnApproachforUsingProb-abilisticRiskAssessmentinRisk-InformedDecisionsonPlantSpeci"c ChangestotheLicensingBasis,May2011(ADAMSAccessionNo.ML100910006),Section5,"QualityAssurance,"providestheNRCsposi-tiononqualityassurance(QA)requirementsforrisk-informedchangesto thelicensingbasis.Speci"cally,thissectioncontainsseveralprovisionsthat shouldbemetwhenalicenseeelectstousePRAinformationtoenhance ormodifyactivitiesthesafety-relatedfunctionsofstructures, systems,andcomponents(SSCs).WhenreferringtoQA,thetermactiv-itiesistypicallyinterpretedtomeandesigning,purchasing,fabricating, handling,shipping,storing,cleaning,erecting,installing,inspecting,test-ing,operating,maintaining,repairing,refueling,andmodifying.Therefore, theproposeddecisionnottoremoveproblematicinsulationrepresentsa modi"cationtoseveralactivitiesthesafety-relatedfunctionsof SSCs,namelytheEmergencyCoreCoolingSystem(ECCS)andContain-mentSpray(CS)systems.1.PleasedescribehowPRAinformationthatisusedtojustifynotre-movingproblematicinsulationincludingbutnotlimitedtothePRA, CASAGrande,andsupportinganalysesmeetsthefollowingprovi-sionsinRG1.174,Section5:

-Usepersonnelquali"edfortheanalysis.

-Useproceduresthatensurecontrolofdocumentation,includ-ingrevisions,andprovideforindependentreview,veri"cation, orcheckingofcalculationsandinformationusedintheanalyses.

-Provide(s)documentationandmaintain(s)recordsinaccordancewiththeguidelinesSection6ofRG1.174.

-Use(s)proceduresthatensurethatappropriateattentionandcor-rectiveactionsaretakenifassumptions,analyses,orinformation usedinpreviousdecisionmakingarechanged(e.g.,licenseevol-untaryaction)ordeterminedtobeinerror.

RequiredResponse,Pg.3372.TheLAR,Volume1describessomequalityassuranceactivitiesthatwereimplementedinsupportoftheLARbutstatesthatCASA GrandeisaproprietaryMATLABapplication,whichwasunavail-abletothe[quality]oversightteam.Therefore,pleaseprovideabrief summaryofthesoftwareQA(SQA)programforCASAGrandeand theanticipateddatewhentheCASAGrandesoftwarewillbecome compliantwiththatSQAprogram.Describeanystandardsandupon whichtheSQAisbased.

RequiredResponse,Pg.3373.IdentifyanyQAprogramsthatwereemployedforanytraditionalengineeringanalyses/calculationsperformedinsupportoftheLARTuesday1 stMarch,2016:19:32,Page83of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONandstatewhethertheseprogramsmeet10CFR50,AppendixBrequirements.

RequiredResponse,Pg.3384.DescribetheQAprogramemployedbyeachvendororcontractorthatperformedcalculationsoranalysesusedtosupporttheLAR.

ExplainwhethervendorQAprogramswereassessedbySTPNOCfor compliancewithapplicableQArequirements.

RequiredResponse,Pg.338

• TreatmentofUnanalyzedPlantConditions1.RG1.200,Revision2,AnApproachforDeterminingtheTechnicalAdequacyofProbabilisticRiskAssessmentResultsforRisk-Informed Activities,Revision2(ADAMSAccessionNo.ML090410014),Sec-tion1.4,"PRADevelopment,Maintenance,andUpgrade,"statesthat plantinformationusedintheProbabilisticRiskAssessment(PRA)

(e.g.,expectedthermal-hydraulicplantresponsetodtstatesof equipment)shouldbeasrealisticaspossible.Verifythatthecondi-tionalsplitfractionvalues(i.e.,failureprobabilitiesusedbyPRA) forsumpfailureandin-vesselfailurearebasedonCASAGrande simulationsthatrepresentaccuratelyplantconditionsforeachacci-dentsequencerelevanttotheLAR,orjustifythatthechosenfailure probabilitiesareupperboundsforanyplantconditionsthatmight occurforagivenscenario.Forexample,forplantconditionswherea simulationisimpractical,unnecessary,ornotperformedforanyother reason,asplitfractionvalueof1.0shouldbeassignedoraqualitative argumentshouldbemadetoselectanexistingCASAGranderesult asbounding.BasedoninformationprovidedintheLARVolumes2 and3,thisapproachisalreadyemployedforpumpstates.Eachofthe 64pumpstatesidenti"edintheLARwereassignedconditionalsplit fractionvaluesforsumpandin-vesselfailurethatwerebasedon:

-CASAGrandesimulations(pumpstates1,22,9,26,43)

-QualitativeargumentsastowhyexistingCASAGranderesultsarebounding(the11boundedstates)

-Assignedaconditionalcoredamageprobabilityof1.0(48otherpumpstates)Asimilarveri"cationthatassignedfailureprobabilitiesarerealisticorboundingshouldbeappliedtoallotherunanalyzedplantconditions includingbutnotlimitedto:

-Numberofcontainmentfancoolersnotequalto6

-Failureofcontainmentisolation

-FailureofoperatorstosecureonetrainofCSearly

-FailureofoperatorstosecureremainingtrainsofCSlate

-FailuretoswitchtohotleginjectionpriortosecuringCStrains

-Failuretoswaptohotleg(HL)recirculation

-Failureofarunningpumpfollowingasuccessfulstart

-Failureofoneormoreresidualheatremovalsystemheatex-changersTuesday1 stMarch,2016:19:32,Page84of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONTherefore,providetheresultsofasystematicreviewofallaccidentsequencescontainingatopeventcorrespondingtooneoftheseven GSl-191failuremodes.Foreachsequence,provideoneofthefollow-

ing:(a)Con"rmationthatthesplitfractionsassignedtosumpandin-vesselfailurewerederivedfromCASAGrandesimulationsthat areconsistentwiththespeci"cplantconditionsassociatedwith thesequence(i.e.,availabilityofplantequipment,success/failure ofoperatoractions,etc.).(b)TechnicalbasisforconcludingthattheexistingCASAGrandesimulationprovidesresultsthatareapplicableorbounding(c)Con"rmationthattheconditionalsplitfractionvalueforsumporin-vesselfailureweresetto1.0fornon-analyzedcases.RemovedResponse,Pg.344

• HumanReliabilityAnalysis7.RG1.174,Sections2.3.1and2.3.2statethatthescopeandlevelofdetailofthePRAmodelmustbesttomodeltheimpact oftheproposedchange.NRCletterdatedApril15,2014(ADAMS AccessionNo.ML14087A075),includesanumberofRAlsrelatedto thehumanreliabilityanalysis(HRA)usedintheriskassessmentand STPNOCresponsestoRAlsdescribeanumberofhumanactions thatareimportantduringaloss-of-coolant-accident(LOCA).Please describehowthedependencyamongmultiplehumanactions(both thoseinthecleanplantanddebrismodels)inthesamesequence wasassessedforthedebrisPRAmodel.RemovedResponse,Pg.344

• KeyAssumptions/KeySourcesofUncertainty1.RG1.200de"nesakeysourceofuncertaintyasanissuewherenoconsensusapproachormodelexistsandwherethechoiceofapproach ormodelisknowntohaveanontheriskpro"le(e.g.,CDF[core damagefrequency],LERF[largeearly1releasefrequency),

[deltaCDF],[deltaLERF])

2.RG1.174andNUREG-1855,Revision1,GuidanceontheTreatmentofUncertaintieswithPRAs inRisk-InformedDecisionmaking,March2013(ADAMSAccession No.ML13093A346),statethat"consensus"referstoanapproachor modelthathasapubliclyavailablepublishedbasisandhasbeenpeer reviewedandwidelyadoptedbyanappropriatestakeholdergroup.In addition,widelyacceptedPRApracticesmayberegardedasconsen-susmodels.Examplesincludetheuseoftheconstantprobabilityof failureondemandmodelandthePoissonmodelforinitiatingevents.

Finally,modelsthattheNRChasutilizedoracceptedforthespeci"c applicationinquestioncanalsobeconsideredconsensus.

2TheNRCspositionisthatcaseswhereaconsensusmodeldoesexist,butthelicenseechoosesanalternatemodelalsorepresentkeysourcesofmodeluncertaintyiftheyhavean ontheriskpro"le.Tuesday1 stMarch,2016:19:32,Page85of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONRG1.200de"nesakeyassumptionasonethatismadeinresponsetoakeysourceofmodeluncertaintywhereatreasonablealternativeassumptionwouldchangetheplantsriskpro"le.RG1.200statesthatforeachapplicationthatcallsuponthisregula-toryguide,theapplicantidenti"esthekeyassumptionsandapprox-imationsrelevanttothatapplication.Thiswillbeusedtoidentify sensitivitystudiesasinputtothedecision-makingassociatedwith theapplication.Therefore,pleaseprovideatableorotherstructuredresponsethatlistskeysourcesofuncertainty.Foreachkeysourceofuncertainty, pleaseidentifythekeyassumption(s)thatweremadetoaddressitand provideeitherasensitivitystudyintermsofGDF,LERF, andLERForuseaqualitativediscussionastowhyatrea-sonablealternativeassumptionwouldnotcausetheriskacceptance guidelinesinRG1.174tobeexceeded.Thisresponseshouldaddress:(a)Lapproachforchemical(b)Headlosscorrelation(c)Successcriteriaforfuelblockageandboronprecipitation(7.5gramsperfuelassembly(g/FA))(d)Fiberpenetrationmodelforsumpstrainer(e)Theuseofgeometric,ratherthanarithmeticmeanaggregatedvaluesfromNUREG-1829,EstimatingLoss-of-CoolantAccident (LOCA)FrequenciesThroughtheElicitationProcess,April2008 (Volumes1and2:ADAMSAccessionNos.ML082250436and

ML081060300)(f)Thecontinuumbreakmodel(vs.doubleendedguillotinebreak(DEGB)onlymodel)(g)Thequantityandreleaserateofunquali"edcoatingsThere-sponseshouldevaluateeachoftheseareasone-at-a-timeand shouldincludeanaggregateanalysisthatquanti"estheinte-gratedimpactonGDF,LERF,andfromthe sensitivitystudiesthatwereperformed.RemovedResponse,Pg.344

• ValidityofAssumptiononPumpCon"gurations1.Inresponsetoquestion3,PlantCon"guration,oftheApril15,2014,RAI,STPNOCanalyzedtpumpcon"gurationsforCase 22toverifyAssumption2bofVolume3,whichstatedthatacombi-nationofpumpsfailinginthesametrainwouldresultinabounding failureprobabilitycomparedtoothercombinationswiththesame numberofeachtypeofpump(i.e.,highhead,lowhead,andCS).Theresultsofthissensitivityshowedthattheassumptionwasfalseforin-vesselfailureprobabilities.Therefore,non-conservativefailure probabilitieswereassignedtoPRAmodeltopeventsforcertainsce-narios.Thisapproachmayresultinanunderestimationoftheriskof

debris.Tuesday1 stMarch,2016:19:32,Page86of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONFailureoftheselectedpumpcon"guration(Case22)toupholdas-sumption2bcallsintoquestionthecombinationsoftheothercases usedtosimplifytheriskassessment.Therefore:

-Pleasedeterminewhetherassumption2bprovidesrealisticorboundingfailureprobabilitiesforeachpumpstatethatisas-signedanon-unityfailureprobability.

-PleaseprovideCDF,LERF,andusingrealisticorboundingfailureprobabilitiesforallpossiblepumpcon"gura-

tion.RemovedResponse,Pg.345

• CASAGrandetoPRAInterface7.Thelicenseesresponsetoquestion5oftheApril15,2014,RAI,con-tainsa"gureshowingthatthesmallestobservedbreaksizeleading todebris-inducedcoredamagewasapproximately17inches.Thisap-pearstocon"ictwiththeresponsetoquestion1,SuccessCriteria, whichstatedthat"thelargestbreaksizebelowwhichnofailuresre-latedtoeitherthesumporvesselperformancewererecordedduring theCASAGranderunswasaDEGBina5.189diameter(D)inch pipe."Pleaseclarifythesecontradictorystatements.RemovedResponse,Pg.345

• FidelitybetweenRELAPSimulationsandCASAGrande1.Volume6.2describestheRELAPsimulationsthatwereusedtode-terminewhethercorecoolingcouldbeaccomplishedwithpartialor completeblockage.Page123statesthatallthesafetysystemswere assumedtobeavailablethroughoutthetransient.Therefore,itwould appearthatTable2.5.39,CoreBlockageScenariosSummary,(Vol-ume6.2)wouldonlyapplytoscenarioswhereallECCSandCSpumps areavailable(i.e.,Case1).Theresponsetoquestion1,SuccessCri-teria,oftheApril15,2014,RAI,statesthatanalysesperformedin supportoftheLARincludedconsiderationofa6inchhotlegbreak withonlyonetrainofECCSavailable.[emphasisadded].Pleaseclar-ifyifthisreferstoananalysisperformedsubsequenttotheLAR.

Provideadditionaldetailsonthisoranyotheranalysesthatareused tojustifyapplyingtheresultsofTable2.5.39topumpstatesother thanCase1.Includeadescriptiononthequalityassuranceofthese analysesinrelationshiptoquestion1,SuccessCriteria.RoverDpartiallly requiredResponse,Pg.345

• State-of-KnowledgeCorrelation1.RG1.174Section2.5.2statesthatthestate-of-knowledgecorrelationshouldbeaccountedforunlessitcanbeshowntobeunimportant.In question5,UncertaintyAnalysis,oftheApril15,2014,RAI,the NRCrequestedthelicenseetoclarifywhythestate-of-knowledge correlationwasnotappliedtotheLOCAfrequenciesusedbythePRA andCASAGrande.STPsresponsestatedthat...dependenceofthe PRAandCASAGrandeontparametersoftheLOCAbreakTuesday1 stMarch,2016:19:32,Page87of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONfrequenciesisstsoasnottowarrantcorrelationbetweenthePRAandCASAGrande.Thisanswermaynotbeinaccuratebe-causethechoiceofLOCAfrequencypercentileboththeab-soluteLOCAfrequency(usedbythePRA)andtheshapeofLOCA frequencyversusbreaksizecurve(usedbyCASAGrande).There-fore,boththePRAandCASAGranderelyonthesameunderlying parameterandthestateofknowledgecorrelationapplies.Thisposi-tionwascommunicatedtothelicenseebytheAdvisoryCommittee onReactorSafeguards(ACRS)duringthemeetingonSeptember3, 2014(ADAMSAccessionNo.ML14266A510),andbytheNRC duringtheauditconductedfromSeptember15-17,2014.Pleasere-viseyouranalysisbycorrelatingtheLOCAfrequenciesusedbythe PRAandCASAGrande.PleasealsoprovideupdatedCDF,LERF, abasedonmeanvaluesresultingfromthepara-metricuncertaintycalculationthatproperlyconsidersthecorrelation betweentheinitiatingeventfrequenciesandthefailureprobabilities (sumpandin-vessel)fordebris-relatedevents.RemovedResponse,Pg.346

• SelectionofJohnsonParameters1.Intheresponsetoquestion4,UncertaintyAnalysis,oftheApril15,2014,RAI,STPNOCstatedthatitwasnotpossibletoapproximate theNUREG-1829meanfrequencieswithtselectionsofthe

parameter.NRCindependentanalysesindicateotherwise;forex-ample,thefollowingalternative"tsyieldsmeansthatarerelatively closetothosetabulatedinTable2.2.2oftheVolume3submittal.

PleaseevaluatethesensitivityoftheCDFandLERFondtse-lectionsofboundedJohnsondistribution"ts,suchasthealternative "tinthetablebelow.RemovedResponse,Pg.346Size(in)5 th1/yrMedian1/yrMean1/yr95 th0.50.0000680.000630.0018530.00714.625380.6712351.49E-0511.6255E-068.9E-050.0004080.00164.5513110.5680398.48E-080.26842723.69E-066.57E-050.0003010.001184.5943710.5683225.61E-080.21291432.1E-073.4E-061.59E-056.1E-056.0243480.5683772.31E-80.135431 66.3E-081.08E-065.16E-61.98E-056.1942460.564654.59E-090.062491 71.46E-083.04E-071.67E-066.34E-066.5299870.5413771.4E-110.052616 144.1E-101.2E-081.94E-075.8E-076.1425610.4226241.69E-100.024278 313.5E-111.2E-093.21E-088.1E-86.2071660.3891481.77E-110.011.4.2EMCB:MechanicalandCivilEngineeringBranch2.InaletterdatedDecember13,2013,thelicenseeexplainsthatthestrainerswereanalyzedfortwoloadcases.Case1correspondstothemaximum temperatureandalowdtialpressurewhichoccursearlyfollowinga loss-of-coolantaccident,whiledebrisloadingislow.Case2correspondsto amaximumtialpressure,whichoccurslaterwhendebrisloading isatamaximum,andcorrespondstoalowertemperature.Inbothcases theinteractionratiosaremaintainedbelow1.However,itisuncleartoTuesday1 stMarch,2016:19:32,Page88of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtheU.S.NuclearRegulatoryCommissionthatthesetwoloadcasesrepresentthemostlimitingloadingconditions,andboundallotherpossible temperatureandpressurecombinations.Therecouldbeacasewherethe tialpressureduetodebrisloadingincreasesatafasterratethan theyieldstressofthematerialincreasesduetothetemperaturedrop.ExplainthebasisforconcludingthatCase1andCase2aretheboundingpost-accidentloadingconditionsforthestrainers(i.e.,theyboundallother pressureandtemperaturecombinations).

RequiredResponse,Pg.3461.4.3ESGB:SteamGeneratorTubeIntegrityandChemicalEngi-neeringBranch

• Chemical23.DuringtheNRCauditinSeptember2014,representativesfromSTPNOCstatedthatthechemicalevaluationmodelwasbeing changedfromthechemicalbump-upfactormultiplierdiscussedin thelicenseessubmittaldatedNovember13,2013(ADAMSAccession No.ML13323A190),toanalternatechemicalmodelthatusesanad-ditivechemicalheadlossfactordeterminedfromthechemicalloading termL.Assumingthebump-upfactorapproachisnolongerbe-ingpursued,theNRChasreconsideredpreviouschemical relatedRAlsanddeterminedthatthefollowingApril15,2014,RAI questionsarenolongerrelevanttothenewchemicalmodel:1a-d,3á,

4,5,9,17,and18a-c.Pleasecon"rmthatthesunderstanding iscorrect.RemovedResponse,Pg.34624.TheNRChasreviewedtheoverviewofanalternatechemicalapproachcontainedinEnclosure1toAttachment5,Quan-ti"cationofChemicalHeadLossEpistemicUncertainty;Basisfor IncrementalChemicalHeadLossEpistemicUncertainty,contained inthelicenseesletterdatedJuly15,2014(ADAMSAccessionNo.

ML14202A045).Thisenclosureprovidesanoverviewofthealternate chemicalmethod.(a)PleaseprovideadetaileddescriptionofthischemicalheadlossmodelanditsapplicationtotheSTPplant-speci"cchemicalef-fectsanalysissuchthattheNRCcanperformathorough reviewandevaluation.(b)AspartofthedetaileddescriptionandbasedonCASAGranderealizations,pleaseprovideahistogramshowingchemicalhead loss(feet)onthex-axisandnumberofoccurrencesonthey-axisforthemedium-breakLOCA(MBLOCA)andlarge-break (LBLOCA)categories.Pleaseensurethebinselectionsallowthe NRCtodiscriminatetoutcomesthatresultinac-ceptableheadloss.(c)PleasediscusswhetherthechemicalheadlossdeterminedfromtheLmethodisindependentofthedebrisbedorinsomewaycorrelatedwiththedebrisbed.Tuesday1 stMarch,2016:19:32,Page89of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Pleasedescribeindetailhowthenewchemicalmodelwillac-countforuncertainties.Someexamplesofuncertaintiesinclude:

variabilityinchemicalheadlossbehavior(e.g.,anapproximate 40percentdinheadlossresultingfromachangetothe precipitateadditionsequenceinEnclosure1,Figure9),variabil-ityinheadlossacrosstdebrisbedsforthesametype andquantityofprecipitate,dincorrosion/leachingbe-haviorbetweentestmaterialsandplantmaterials,variabilityin temperatureorpHcomparedtotesting,otherpost-LOCAcon-ditions(e.g.,radiological)notpresentduringtesting.RemovedResponse,Pg.34725.TheNRChasseveralquestionsrelatedtoFigure14intheafore-mentionedEnclosure1toAttachment5.(a)GiventheheadlossresponsetochemicalprecipitateadditionshownearlierinFigures1and2,itseemsmoreappropriateto modelheadlossinanon-linearmanner.Pleasediscussanyplans tofurtherdevelopthemodel.(b)TheNRCsisoftheopinionthatthe4thBahndatapointplacementinthisplotisnotappropriategiventhatthetestloop wasshutdownatthispointsincethetestloopheadlosslimit hadbeenreached.Pleasediscussaplausiblerangeofheadloss forthistesthaditnotbeenstoppedandhowthatwould thechemicalheadlosscorrelation.(c)Withoutconsiderationofitem(b),theNRCcalculatedagreaterchemicalheadloss(CHL)value(approximately0.7feet) whenscalinga13feetofwaterresulttotheSTPstrainertest conditionsaccordingtoEquation2.Pleaseprovideacopyofthe calculationshowingthescaledvalueisapproximately0.4feet.(d)WhiletheNRCagreesthatcomparisonofchemicaltestingmayprovideinsight,therelationshipbetween"owand chemicalheadlossmaybemorecomplexthanasshownbyEqua-tion2.Pleaseprovideabasisforthisscalingequationordiscuss thelimitationsthatmayexistwhenextrapolatingdataovermore thananorderofmagnitudein"owrates.RemovedResponse,Pg.34726.Figure25inEnclosure1toAttachment5ofletterdatedJuly15,2014,showsnewaluminumreleaseequationsthatappeartobebased onexperimentsrunforSouthernNuclearOperatingCompany.(a)PleaseprovideacopyoftheReference17(CHLE-SNC-005BenchTest)ReportthatcontainsthisdatasothattheNRCmay understandhowthesetestswereperformed.(b)Con"rmthattheorangelineinFigure25representsthe1600seriestests.(c)ThealuminumreleasemodelappearstobepredictingthesamedataasinFigure24,whichwasusedtodevelopthemodel.Please clarifyifanyadditionaldatawasusedtodevelopthemodel.RemovedResponse,Pg.34727.AlimitedreleaseofaluminumduringchemicaltestingisoneofthekeyitemsSTPisrelyingonforconcludingSTPhasrela-Tuesday1 stMarch,2016:19:32,Page90of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtivelyminorchemicalInESGBquestion13.b.oftheApril15,2014,RAI,theNRCaskedifthetwopartsof hadbeentestedtocomparetheiraluminumrelease.Thelicensees responseprovidedscanningelectronmicroscopeimagesalongwith energydispersivespectroscopy(EDS)andx-rayphotoelectronspec-trometry(XPS)results.Giventhatthetwopartsofwereusedindttestconditions,thattheywerevisuallyobservedtohavettexture andappearance,andthattheTable1elementalcompositionsindicate potentiallysigni"cantinkeyelements(e.g.,Al,0,P),the NRCthinksitisimportanttoverifythatthecorrosionbehavior ofthetwopartsissimilar.Forexample,onewaytoverify similitudewouldbetorunadirectcomparisonofaluminumrelease inbenchtestsathigherpost-LOCAtemperaturestodetermineifthe aluminumreleasewasreasonablysimilar.Pleaseprovideacomparison ofthecorrosionbehaviorofthetwopartsofRemovedResponse,Pg.34728.Sincemultipletestssuggestaluminumcorrosionwillbeinhibitedbyphosphateafterarelativelyshorttimeintothepost-LOCAECCS missiontime,understandingthecorrosionbehaviorofaluminumat elevatedtemperaturesbecomesveryimportant.Recentaluminum corrosiontestingbyanotherlicensee(seeADAMSAccessionNo.

ML141848509,Slide18)showedthatfortheirplant-speci"ccondi-tions,signi"cantlylongertestdurationsat195degreesFahrenheit

(F)didnotreleaseanequivalentquantityofaluminumasshortertimeathighertemperatures.Pleasediscusstherelevanceofthesere-sultstotheSTPchemicalapproachforaluminumreleaseat highertemperatures.Pleaseincludeinthatdiscussiontherangeof postulatedplant-LOCAtemperaturepro"lesrelativetotheCHLE testMBLOCAandLBLOCApro"lesandifanyadjustmentsare neededtothealuminumreleaseratesattemperaturesgreaterthan

185F.RemovedResponse,Pg.34729.InSection2.1.1(ZincPhosphate)ofEnclosure1toAttachment5ofthelicenseesletterdatedJuly15,2014,thediscussionstatesthe following:WhenzinccorrosionmaterialswereincludedintheSTPrisk-informedtests,headlossresponsewasobservedduring theinitialhouroftesting;however,additionaltestsindicated thattheheadlossresponsetothezincproductwaslikelythe resultofinitialdissolutionofasurfacelayerandnotfrom transportofacontinuouslygeneratedzinccorrosionproduct H20).Therefore,theinitialzincproductre-leaseistreatedasaparticulatesourceandnotconsidereda zincchemicalproduct.SinceH20isunlikelyto transporttothestrainerand,giventhatOption1CHLis intendedtoproduceconservativeoroverestimatedCHLre-sponsetoidenti"edprecipitateloads,H20gen-erationisignoredintheCHLcorrelationdevelopment.Tuesday1 stMarch,2016:19:32,Page91of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONGiventhesigni"cantquantitiesofzincpresent,theNRC"ndsitwouldbeappropriateforachemicalmodeltoaccountforzinc.

Dissolutionofgalvanizedsteelorinorganiczinccoatingsmayoccur atthelowerpHbeforethetrisodiumphosphate(TSP)fully dissolvestoadjustthepHtoanalkalinevalue.Dissolvedzincwould thenbeavailabletoreactwiththephosphate.Inaddition,someper-centageofthegalvanizedsurfacescouldbesusceptibletohavingzinc corrosionproductknockedbywaterfallingfromthepipebreak, drains,etc.TheNRCrecognizesitmaybeappropriatetomodel zincproductsseparatelyfromamorphousaluminumhydroxidetype precipitatesifwarrantedbytheheadlossresponseacrossadebrisbed representativeofasumpstrainerbed.Pleaseprovidethequantityof zincthatisincludedintheparticulatesource,howthisamount ofzincheadlossandifanadditionalzincproductshouldbe includedinthemodel.RemovedResponse,Pg.34830.Figure21inEnclosure1toAttachment5ofthelicenseesletterdatedJuly15,2014,impliestheWCAP-16530releaserateequa-tionsarebeingincorporatedintoCASAGrandewhichisnotthe caseforaluminum.Pleaseclarifywhich,ifany,WCAP16530-NP-A,EvaluationofPost-AccidentChemicalinContainment SumpFluidstoSupportGSl-191,March2008(ADAMSAccession No.ML081150379),releaseequationswillbeusedwiththealternate chemicalheadlossmodelapproach.RemovedResponse,Pg.34831.Thechemicalheadlossisdeterminedbasedonchemicalprecipitateloadingperstrainer(gramspermetersquare(g/m 2)).Pleasedescribehowtheplant-speci"cincorporationofthismodelaccountsforthe greaterchemicalheadloadingforthecaseswherelessthanthree trainsoperatefollowingaLOCA.RemovedResponse,Pg.34832.ItisuncleartotheNRChowSTPNOCsresponsetoESGBquestion14.a.oftheApril15,2014,RAI,evaluatedtheradiation onprecipitates.Explainhowuncertaintiesfromtheradiation onprecipitateformationareconsideredintheSTPchemical analysis.RemovedResponse,Pg.34833.IntheresponsetoESGBquestion21oftheApril15,2014,RAI,themassof24poundsforaCRUDreleasefollowingaLOCAisbased upontheElectricPowerResearchInstitute(EPRI)Boron-Induced AnomalyestimatesoffueldepositsthatwouldaCRUD inducedpowershift(CIPS).Whilethismaybeanadequateprediction forCIPSsusceptibility,itdoesnotassessthetotalavailabletransient CRUDlayerintheprimarycoolantsystem.Thefuelsurfaceareais approximately30percentofavailablereactorcoolantsystem(RCS) surfacewithothersurfacessuchaspipingandSteamGeneratortub-ingmakingupmostoftheremainingsurfaceareas.TheEPRIPressurized-WaterReactor(PWR)PrimaryWaterChem-istryGuidelinesstate,inpart:Core"owtransientsshouldbeminimizedtominimizepar-ticulateentrainmentwhichwillincreasedoseratesandpar-Tuesday1 stMarch,2016:19:32,Page92of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONticulatecontaminationlevelsinlow"owregions.Wallshear,whichisapproximatelyproportionaltothesquareofthecoolant velocity,istheprimaryfactorpromotingparticulatereleases subsequenttoshutdown.Asmoothtransitiontoonepump operationisconsideredappropriatetoreduceshearandmin-imizeparticulatereleasesduringtheshutdowntransient.DuringareactortripfollowingaLOCAthereisnosmoothtransi-tionwithliquidandgaseous"owplussolidsentrainment.Thermal, hydraulicandchemicaltransientsareallpresent,simultaneously.One ofthemostsigni"cantchemicalchangesisthepresenceofbothhydro-genandoxygeninthewater"owingtothesumpaswellasbeingre-circulatedbackthroughthereactorcore.Thisuncontrolledchemistry conditionleadstobothreductiveandoxidativeprocessesoccurring simultaneouslyleadingtoparticulateformation.TheEPRIPWRPri-maryWaterChemistryGuidelines(Table3-5ofSection3.8)identi"es analysestobeperformedbyChemistryduringanormalshutdown, including"lterableandnon-"lterable:radioactivecorrosionproducts, elementalnickelandiron.Therefore,theChemistrydepartmentmay havethisinformationrelatedtonormalshutdownsandtransientshut-downs.Therefore,theNRCrequeststhatthelicenseedetermineifhis-toricalinformationisavailableconcerningcrudreleasefromnormal shutdownsandunplannedtripsandtore-evaluatethecrudrelease estimatebasedonanyadditionalinformation,includingreleasefrom allRCSsourcesduringaLOCA.

RequiredResponse,Pg.34834.Pleaseclarifythebetweenthe"beramountsshownintheTable2andFigure3inEnclosure1ofthelicenseesletterdatedJuly 15,2014.RemovedResponse,Pg.349

• Coatings8.Withrespecttoquestion1oftheApril15,2014,RAI,theresponsedoesnotseemconsistentwiththecurrentNRCspositionondebris characteristicsforunquali"edcoatings.Thetestingyoureferencedis notapplicabletounquali"edcoatings.Thispositionisdescribedin theNRCreviewguidanceavailableatADAMSAccessionNo.

ML080230462.Pleaseprovidearevisedanalysisfortheunquali"ed epoxycoatingsinquestion.RemovedResponse,Pg.3509.Thelicenseesresponseinquestion2oftheApril15,2014,RAI,statedthataZoneofIn"uence(ZOI)of4D(4Diameter)wasusedfor inorganiczinccoatings.Thispositionisinconsistentwiththecurrent NRCposition.BasedonthelatesttestdataavailabletheZOIfor inorganiczinccoatingsshouldbe1OD.Adescriptionofthisposition isavailableatADAMSAccessionNo.ML100960495.Pleaseprovide arevisedanalysisfortheZOIofinorganiczinccoatings.

RequiredResponse,Pg.35010.Withrespecttoquestion6oftheApril15,2014,RAI,thereductionscreditedfordebrisgeneratedbyunquali"edcoatingsinuppercon-tainmentisinconsistentwiththecurrentNRCposition.BothTuesday1 stMarch,2016:19:32,Page93of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthetreatmentoffailurepercentagesandfailuretimingarebasedonEPRItestingthatthehaspreviouslyissuedpositionson.

guidancefoundatADAMSAccessionNo.ML080230462describesthe spositionwithrespecttothistesting.InadditiontheNRC concernsregardingthefailuretimingbeingbasedon"lterdata(as describedintheoriginalquestions6band6c)arenotadequatelyad-dressedbyyourresponses.Pleaseprovidearevisedanalysisforthe unquali"edcoatingsinuppercontainment.

RequiredResponse,Pg.3501.4.4SCVB:ContainmentandVentilationBranch10.

Background:

Theresponsetoquestion3.aoftheApril15,2014,RAI,doesnotappeartoprovideadequatejusti"cationfornotrevising theUpdatedFinalSafetyAnalysisReport(UFSAR)descriptionof thecontainmentheatremovalanalysis.Theresponsetoquestion3.c referstoaproposedUFSARdescriptionoftheriskassessmentgiven inEnclosure3,Attachment2ofthelicenseesletterdatedNovember 13,2013,whichdoesnotprovidearevisedlicensingbasisdescription ofthecontainmentheatremovalanalysis.Thelicenseesresponsetoquestion4.aoftheApril15,2014,RAI,doesnotprovideadequatejusti"cationfornotrevisingtheUFSAR descriptionofthe"ssionproductremovalanalysis.Theresponseto question4coftheApril15,2014,RAI,referstoaproposedUFSAR descriptionoftheriskassessmentgiveninEnclosure3,Attachment2 ofthelicenseesletterdatedNovember13,2013,whichdoesnotpro-videarevisedlicensingbasisdescriptionoftherevised"ssionproduct removalanalysis.Pleaserefertothefollowingexcerpttakenfromthelicenseesresponsetoquestion3.boftheApril15,2014,RAI:AsdescribedintheLAR,theproposedexemptionsfromGen-eralDesignCriteria(GDC)-35,EmergencyCoreCooling, GDC-38,ContainmentHeatRemoval,andGDC-41,"Con-tainmentAtmosphereCleanup"areforapprovalofarisk-informedapproachforaddressingGSl-191andrespondingto GenericLetter(GL)2004-02forSTPUnits1and2asthe pilotplantsforotherlicenseespursuingasimilarapproach.

Asfurtherdescribed,STPNOCseeksNRCapprovalbased onadeterminationthattheriskinformedapproachandthe riskassociatedwiththepostulatedfailuremechanismsdueto GSl-191concernsmeetstheguidance,keyprinciplesforrisk-informeddecisionmaking,andtheacceptanceguidelinesin RG1.174.STPisnotproposingtoapplytherisk-informed approachtorevisethelicensingbasisforcontainmentdesign describedintheUFSAR.Theproposedriskassessmenteval-uatesaspectrumofLossofCoolantAccident(LOCA)sce-nariostoquantifytheamountofdebrisofvarioustypesthat mightbegeneratedandtransportedtotheemergencysumps, andhowthatdebrismightctavailableNPSH[netpositiveTuesday1 stMarch,2016:19:32,Page94of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsuctionhead]forEmergencyCoreCoolingSystem(ECCS)andContainmentSpraySystem(CSS)pumpstakingsuction fromthesumpsintherecirculationmode.Italsoevaluates potentialtransportofdebristothereactorcore.Itcalculates failureprobabilitiesthatarefedtotheSTPPRA.

Concern:Theagreesthatthecurrentlylicenseddesignandcon-"gurationoftheCSSandECCSasdescribedintheUFSARwillnot beimpactedbytherisk-informedresolutiontoGSl-191exceptforthe changeinthesumpstrainerdesign.However,theNRCisnot inagreementthattheUFSARdescriptionofthelicensingbasiscon-tainmentheatremovalanalysis.whichusesCSS;thelicensingbasis containment"ssionproductremovalanalysis.whichalsousesCSS; andthelicensingbasis10CFR50.46analysis.whichusesECCS, willnotbeimpactedbytherisk-informedresolutiontoGSl-191.For breaksthatproducelessornodebris,thelicensingbasisanalysis shouldbebasedonthedeterministicapproachwithouttakingex-emptionfromGDCs35,38,and41.Forbreaksthatproducelarge amountofdebrisandwithouttakingexemptionsfromtheGDCs(for exampleexemptionfromassumingsinglefailure)itisnotpossible tomeettheacceptancecriteriaforpeakcladdingtemperatureand containmentheatand"ssionproductremoval,therisk-informedap-proachmaybeusedandexemptionfromtheGDCsmayberequested forthesespeci"cbreaksonly.TheNRChasdevelopedthe"owchartshowninFigure1(onpage19ofthisRAI)forde"ningtheLOCAcontainmentNPSHlicens-ingbasisanalysis(whichisthemostsigni"cantpartofcontainment heatremovalanalysis)fordeterministicandrisk-basedGSl-191res-olution.Thesuggeststhelicenseetodevelopsimilar"owcharts de"ningthedeterministicandrisk-based"ssionproductremovaland ECCSlicensingbasisanalysis.

Question:RG1.174requiresthatthelicenseeshouldidentifythoseaspectsoftheplantslicensingbasisthatmaybebythe proposedchange,includingbutnotlimitedtorulesandregulations, UFSAR,technicalspeci"cations,licensingconditions,andlicensing commitments.NUREG-0800,StandardReviewPlanfortheReview ofSafetyAnalysisReportsforNuclearPowerPlants,(SRP)Chap-ter19.2,ReviewofRiskInformationUsedtoSupportPermanent Plant-speci"cChangestotheLicensingBasis:GeneralGuidance, Section111.1alsorequiresthatthechangesintheplantlicensingba-sisshouldbeappropriatelyre"ectedinlicensingdocumentssuchas technicalspeci"cation(TS),licenseconditions(LCs),andUFSAR.

Therefore,thecurrentlicensingbasisforthecontainmentheatre-movaldescribedinUFSARChapters6and15mustberevisedby includingthedescriptionforthebreaksforwhichpartialorcomplete exemptionfromGDCs35,38,and41isrequested.(a)ProvideUFSARrevisionsofChapters6and15forthedescriptionofrevisedlicensingbasisanalysisofthecontainmentheatremovalTuesday1 stMarch,2016:19:32,Page95of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONforthebreaksforwhichexemptionfromGDC-38isrequested.(b)ProvideUFSARrevisionsofChapter6forthedescriptionofrevisedlicensingbasisoftheanalysisofthecontainmentspray system-iodineremovalforthebreaksforwhichexemptionfrom GDC-41isrequested.(c)ProvideUFSARrevisionofSection6.3forthedescriptionofrevisedlicensingbasisanalysisoftheECCSforthebreaksfor whichexemptionfromGDC-35isrequested.

RequiredResponse,Pg.35011.Pleasenotethattheuseofrisk-basedapproachforresolutionofGSl-191requiresachangeinthelicensingbasisfortheCSSoperatingin thepresenceofdebris.RG1.174describesanacceptableapproachfor assessingthenatureandimpactofproposedlicensingbasischanges.

ThisRGrequiresthatthelicenseeshouldidentifyallSSCs,proce-dures,andactivitiesthatarecoveredbythelicensingbasischange beingevaluated.Theresponsetoquestion1.aoftheApril15,2014,RAI,statesthattheCSSistheonlysystemforwhichtheexemptionfromGDC-38is requested.NotethattheCSShasassociatedsupportingsystemssuch asthesafety-relatedelectrical,EmergencyDieselGenerator(EDG),

instrumentationandcontrol(l&C),andcoolingwatersystems.There-fore,asrequiredbyRG1.174,pleaseidentifyalltheassociatedSSCs, proceduresandactivitiesthatsupporttheoperationoftheCSSfor containmentheatremovalinthepresenceofdebris.

RequiredResponse,Pg.35312.Theresponsetoquestion1.boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-38willnotbemet.ThekeyGDC-38requirementstobemetfortheCSSsystemdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Performthesafetyfunctionofcontainmentheatremoval,andrapidlyreducethecontainmentpressureandtemperatureand maintainthematacceptablylowlevel.

RequiredResponse,Pg.353(2)Safetyfunction(1)shallbeperformed follow ingany LOCA.RequiredResponse,Pg.354(3)Safetyfunction(1)shallbeperformed in the pres ence or ab sence of Loss ofsitePower(LOOP).Response,Pg.354(4)Safetyfunction(1)shallbeperformed in the pres ence of aworst sin gle fail ure.RequiredResponse,Pg.354Notethatrequirement(2)coversallpostulatedLOCAsofanybreaksize,includingthemostlimitingfromdebrisgeneration,containment peakpressure,andcontainmentpeaktemperaturestandpoint.Pleaseprovidethefollowinginformation:(a)IsfullexemptionfromtheGDC-38requirements(2),(3),and(4)requested?Ifso,irrespectiveofthebreaksize,breaklocation,or quantityofdebrisgeneration,allCSStrainsalongwiththeir supportingsystemmaybeused.Pleaseprovidejusti"cationfor theproposalofafullexemptionfromtheserequirements.

RequiredResponse,Pg.354Tuesday1 stMarch,2016:19:32,Page96of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(b)IsapartialexemptionfromGDC-38requirement(2)requested(i.e.,forspeci"cLOCAsonlyandfullexemptionfromrequire-ments(3)and(4))?Ifso,specifytheLOCAsintermsoflocation, breaksize,anddebrisgenerationrateforwhichtheexemptionis requestedfrommeetingrequirement#(3)and#(4),andprovide justi"cationfortheexemptionrequest.

RequiredResponse,Pg.35413.Theresponsetoquestion2.aoftheApril15,2014,RAI,statesthattheCSSistheonlysystemforwhichtheexemptionfromGDC-41is requested.NotethattheCSSalsohasassociatedsupportingsystems towhichGDC-41mayapply.Pleaselistalltheassociatedsystems thatsupporttheoperationoftheCSS;suchasthesafety-relatedelec-trical,EOG,l&C,andcoolingwatersystems.Thereforeasrequired byRG1.174,pleaseidentifyalltheassociatedSSCs,proceduresandactivitiesthatsupporttheoperationoftheCSSfor"ssionproduct removalinthepresenceofdebris.

RequiredResponse,Pg.35514.Theresponsetoquestion2.boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-41willnotbemet.ThekeyGDC-41requirementstobemetfortheCSSsystemdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Pleaselistsystemsrequiredtoperformthesafetyfunctionofcontrolling"ssionproducts,hydrogen,oxygen,andothersub-stancesthatmaybereleasedintothereactorcontainmentto reduce,consistentwiththefunctioningofotherassociatedsys-tems,theconcentrationandqualityof"ssionproductsreleased totheenvironmentandtocontroltheconcentrationofhydrogen andoxygenandothersubstancesinthecontainmentatmosphere toassurethatcontainmentintegrityismaintained.

RequiredResponse,Pg.355(2)Safetyfunction(1)shallbeperformedfollowingallpostulatedaccidents.

RequiredResponse,Pg.355(3)Safetyfunction(1)shallbeperformedbyprovidingsuitablere-dundancyincomponentsandfeatures,suitableinterconnections, leakdetectionandisolation,andcontainmentcapabilities.

RequiredResponse,Pg.355(4)Safetyfunction(1)shallbeperformedinthepresenceorabsenceofLOOP.RequiredResponse,Pg.355(5)Safetyfunction(1)shallbeperformedinthepresenceofaworstsinglefailure.

RequiredResponse,Pg.355Pleaseprovidethefollowinginformation:(a)IsfullexemptionfromtheGDC-41requirements(2),(3),(4),and(5)requested?Ifso,thanirrespectiveofthebreak size,breaklocation,orquantityofdebrisgeneration,allCSS trainsalongwiththeirsupportingsystemmaybeused.Please providejusti"cationfortheproposalofafullexemptionfrom theserequirements.

RequiredResponse,Pg.355(b)IsapartialexemptionfromGDC-41requirement(2)requested(i.e.,forspeci"cLOCAsonly,andfullexemptionfromre-quirements(3),(4),and(5))?Ifso,specifytheLOCAsinTuesday1 stMarch,2016:19:32,Page97of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONtermsoflocation,breaksize,anddebrisgenerationrateforwhichtheexemptionisrequestedfrommeetingrequirements (3),(4),and(5),andprovidejusti"cationfortheexemption

request.RequiredResponse,Pg.35615.Theresponsetoquestion9.aoftheApril15,2014,RAI,statesthattheECCSistheonlysystemforwhichtheexemptionfromGDC-35isrequested.PleasenotethattheECCSwhosesubsystemsare HighHeadSafetyInjection(HHSI)andtheLowHeadSafetyInjec-tion(LHSI)systemsarenottheonlyonesforwhichtheproposed exemptiontoGDC-35wouldapply.Listallofthesupportingsystem thatsupporttheoperationoftheHHSIandLHSIsubsystems;for examplethesafety-relatedelectrical,EDG,l&C,andcoolingwater systems.ThereforeasrequiredbyRG1.174,pleaseidentifyallthe associatedSSCs,proceduresandactivitiesthatsupporttheoperation oftheHHSIandLHSIsystemsinthepresenceofdebris.

RequiredResponse,Pg.35616.Theresponsetoquestion9boftheApril15,2014,RAI,doesnotstatewhichrequirementsofGDC-35willnotbemet.ThekeyGDC-35requirementstobemetfortheECCSdesign,concurrentwith functioningofassociatedsystemsareasfollows:(1)Performthesafetyfunctionoftransferringheatfromreactorcoreataratesuchthat(a)fuelandcladdamagethatcouldinterfere withcontinuedeecorecoolingispreventedand(b)clad metal-waterreactorislimitedtonegligibleamounts.

RequiredResponse,Pg.356(2)Safetyfunction(1)shallbeperformed follow ingany LOCA.RequiredResponse,Pg.356(3)Safetyfunction(1)shallbeperformedbyprovidingsuitablere-dundancyincomponentsandfeatures,suitableinterconnections, leakdetectionandisolation,andcontainmentcapabilities.

RequiredResponse,Pg.356(4)Safetyfunction(1)shallbeperformed in the pres ence or ab sence ofLOOP.RequiredResponse,Pg.356(5)Safetyfunction(1)shallbeperformed in the pres ence of aworst sin gle fail ure.RequiredResponse,Pg.357Notethatrequirement(2)covers allpos tu lated LOCAsofanybreaksize,includingthemostlimitingfromdebrisgenerationor peakcladtemperaturestandpoint.Pleaseprovidethefollowing

information:(a)IsfullexemptionfromtheGDC-35requirements(2),(3),(4),and(5)requested?Ifso,irrespectiveofthebreaksize, breaklocation,orquantityofdebrisgeneration,allECCS trainsalongwiththeirsupportingsystemmaybeusedfor performingsafetyfunction(1).Pleaseprovidejusti"cationforrequestingafullexemptionfromtheserequirements.

RequiredResponse,Pg.357(b)IsapartialexemptionfromGDC-35requirement(2)requested(i.e.,forspeci"cLOCAsonlyandfullexemptionfromrequire-ments(3),(4),and(5))?Ifso,specifytheLOCAsinterms oflocation,breaksize,anddebrisgenerationrateforwhich theexemptionisrequestedfrommeetingrequirement#(3),Tuesday1 stMarch,2016:19:32,Page98of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION#(4),and#(5),andprovidejusti"cationfortheexemption request.RequiredResponse,Pg.35717.Inquestion7oftheApril15,2014,RAI,theNRCrequestedthelicenseetoprovidetheequivalentofUFSARSection6.2.1.5,which shoulddescribethelicensingbasisoftheminimumcontainmentpres-sureanalysisforperformancecapabilityofECCSinthepresenceof debrisfortherisk-basedanalysis.SuccessfulfunctioningoftheLHSI, HHSIsystemsandtheCSSinthepresenceofdebrisrequiresex-emptionfromGDC-35andGDC-38.Therefore,inthepresenceof debrisduringLOCAs,thedescriptionoftheminimumcontainment pressureanalysisforperformancecapabilityshouldbedtfrom whatisdescribedintheUFSARSection6.2.1.5.Thelicenseesre-sponsetoquestion7didnotdescribetheproposedcontainmentanal-ysis,includingassumptionsandinputs,performedforthecalculation ofminimumcontainmentpressureinputfortheECCSanalysisthat calculatesthepeakcladdingtemperatureforrisk-informedGSl-191.

Pleasejustifythattheinputsandassumptionsareconservativefor thepurpose.

RequiredResponse,Pg.35718.Pleaseprovidethefollowingadditionalinformationwithrespecttoyourresponsetoquestion3.boftheApril15,2014,RAI:(a)Refertothetableonpage9ofAttachment3tothelicenseeslet-terdatedJune25,2014(ADAMSAccessionNo.ML14178A481),

ofmajorqualitativedforthesubjectSumpPoolTreat-ment,pleaseexplainwhatismeantby:Nodecayheatadded.

MassandenergysubtractedfromthepoolbasedonRELAP-3D instructions.(b)Refertothetablereferencedinitema)forthesubjectPipebreakmass/energysource,pleaseexplainwhatismeantby:

CommunicatedfromRELAP5-3Dviacouplinginterfaceasprob-lemtimeprogresses.ThesourceissplitbyMELCORintopart liquidwater,partsteam,andpartfog.(c)RefertothetableundertheheadingSummaryComparisonofMainParameterValues,onpage10ofAttachment3tothe licenseesletterdatedJune25,2014,pleaseprovidethebasisfor selectingtheRELAP-3D/MELCORvaluesoftheparametersin thetablebelowandhowaretheydetermined:RELAP-3D/MELCORVALUEInitialatmospheretemperature119.93FInitialcontainmentpressure14.94psiaInitialrelativehumidity,partialpressureofwatervapor70%/1,184psiaInitialRWSTtemperature85FSprayactuationtimes15sdelayaftersetpoint,linearramptofull"owFancooleractuationtimes15sdelayaftersetpointTuesday1 stMarch,2016:19:32,Page99of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION(d)Refertothetablereferencedinitemc)fortheCONTEMPTandRELAP-3D/MELCORanalysis,pleaseprovidethebasisfor usingdtvaluesof(1)thermalconductivityofconcrete,(2) thermalconductivityofstainlesssteel,(3)speci"cheatcapacity ofconcrete,(4)speci"cheatcapacityofstainlesssteel,and(5) densityofstainlesssteel.

RequiredResponse,Pg.357Tuesday1 stMarch,2016:19:32,Page100of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION1.4.5SNPB:NuclearPerformanceandCodeReviewBranchTheNRChasreviewedtheSTPRELAP5-3Dwiththe1-Dcoreanal-yses,entitledCoreBlockageThermal-HydraulicAnalysis.TheNRCrecognizesthattheseanalyseshavetheobjectiveofdemon-stratingthatundertheblockedcoreinletcases,twatercanmatch bandmaintaincoolabilityandtheRELAP5analyseshaveshownthe conditionsforwhichthisistrue.However,thealsorecognizesthat whiletwateradditiontothecoreistobejusti"edtomatch/exceed bprecipitationofboricacidinthecorewithvariousblockagesalso needstobeaddressed.Assuch,theanalysesonlyaddressthe"rstcritical issueforlong-termcooling,butwouldrequireanevaluationofprecipitation tobeabletostatethatlong-termcoolinghasbeendemonstrated.With-outtheprecipitationevaluation,long-termcoolingcannotbejusti"ed.It isnotedthattheRELAP5-3Dcodetrackstheboronsoluteconcentration, howeveritdoesnotincludeboricacidbuild-upontheliquiddensityand thestaticheadterminthemomentumequation.Assuch,"owratesand thermalhydraulicbehaviormaybeofconcern.Also,transportproperties withincreasedboricacidconcentrationsisalsoomittedinRELAP5-3D.

TheNRCrequeststhefollowingadditionalinformation:1.Forthesmall2-inchcoldlegbreakofTable2,whilewater"llsthesteamgeneratorcoldsidesspillingovertothehotsideandre"lling thecoretokeepitcooled,thequestionofprecipitationcouldbean issuethatrepresentsfailureforthiscase.Thatis,withthecoreto-tallyblockedthereisnomeansof"ushingtheboricacidbuild-up inthecorethatbeginsuponinitiationofboiling.Ifitassumedno watercanpassthroughtheblockedregionfromcoldsideinjection thenswitchingtohotsideinjectionshouldnot"ushtheboricacid build-upfromthecore.Itwouldbeinstructivetoperformaprecipi-tationcalculationtoshowthetimingforprecipitationoncethecore beginstoboil.SincetheRCSpressureisfairlyhightheprecipitation limitwillbelikewisehigher,butitisnotclearthattheprecipita-tionlimitwillnotbereached.Itappearsthatwiththecoretotally blocked,precipitationcannotbeavoided.Pleaseexplainandprovide anevaluationofprecipitationtimingforthiscase.

RequiredResponse,Pg.3572.Thecaseswithoneassemblyunblocked(centerandperiphery)pre-sentedinFigure32showsadequatewaterentersthecoretomatch bHowever,asboricacidbuildsupinthecore,thedensityin-creasesdegradingthe"owintothecore.Giventhatthedowncomer levelis"xedduetothebreak,"owwouldbeexpectedtodecrease asthedensityinthecoreincreases.Assuch,calculationofthepre-cipitationtimingandmixinginthecoreneedstobeevaluated.Since thereisonlyoneunblockedassemblybottomlocation,itisnotobvi-ousthattheswitchtosimultaneousinjectioncan"ushtheboricacid fromthecorethatbuilds-uppriortotheswitchtoprecludeprecip-itation.Furthermorewithonlytheoneopenassemblyinletpathto thecoreregions,locationsneartheperipherycantrapboricacidandTuesday1 stMarch,2016:19:32,Page101of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONcauselocalbuild-upofconcentrationthatmaynotbe"ushedoutwithhotsideinjection.Itisnotclearthatprecipitationcanbeprecluded fortheseblockedcases.Pleaseprovideadetailedexplanation.

RequiredResponse,Pg.3583.ThecaseinFigure32withthebypassfreeshowsadequatewaterentersthecoreforcooling.Pleaseidentifytheelevationsabovethe bottomofthecorewherethesebypasspathsarelocated.Ifthe"rst bypassislocatedabovethebottomelevationofthecore,thisre-gionofthecorebelowthe"rstbypasspathwilltrapboricacidand build-uptopotentiallyreachprecipitation.Itisnotclearhowthe downwardandthenupward"owcan"ushtheboricacidfromthis lowerisolatedregion.Ifthebypassislocatedatthecorebottomel-evationitisstillnotclearifsimultaneousinjectioncanarrestthe build-upofboricacidand"ushthecorethroughthebypassregion.

Pleaseexplainhowprecipitationispreventedanddemonstratethat RELAP5-3Dcanpredictthecorrect"owsto"ushthecoreunder theseunusual"owpathcon"gurations.SincetheRELAP5-3Dcode doesnotincludethedensityincreaseswithboricacidconcentration, pleaseexplainanddemonstratethatthe"owandmixingbehavior inthecorecanbecorrectlycalculated.Whatvalidationcalculations havebeenperformedtoshowthattheomissioninthemomentum equationdonotprovideexcessive"owandmixingbehavior,noting thatthetransportpropertiesarealsoomittedinthecode.

RequiredResponse,Pg.3584.PleasedescribehowtheadvectionterminRELAP5-3Disnumeri-callyexpressedanddemonstratethatnumericaldoesnot produceerroneousorexcessive"owbehaviorthatcouldchangethe conclusionsofthisanalysis.Sinceadvectionanddcanplay keyrolesinthecalculatedliquidandsteamvelocitiesinthe core,pleasedemonstratethatRELAP5-3Dcanproperlymodelthese Itmaybeadvantageoustosolvethetransportequationwith advectionanddina1-Dpipeand3-Dvolumeusingthesame numericalapproximationinRELAP5-3Dfortheadvectionandthe secondorderviscousdterms.Pleaseshowthatastepfunction densitywaveorconcentrationwavemovingdownthepipedoesnot fromnumericalcharacteristicofthe1-Dupwinddif-ferencingschemethathasbeenemployedinRELAP5codeversions.

RequiredResponse,Pg.3585.Thereviewindicatesthattheswitchtosimultaneousinjectionforsomeofthecasesoccursatttimesforthevariousbreaks evaluated.Forexample,Figure8showstheswitchtimeatabout 32,000secondsforthe2-inchhotlegbreakwhileFigure27shows about22,000secondsfortheswitchforthedoubleendedguillotine hotlegbreak.TypicallytheswitchtimeisanEmergencyOperating Procedureactionandoccursatonetimethatistlyearly enoughthatassuresallbreaksizesare"ushedpriortoreachingthe precipitationlimitforthelimitingcase.Theseshouldhave noimpactontheanalysisconclusionsbutpleaseexplainthebasisand verifythattheuseofdttiminghasnoimpactontheresultsand conclusionsanddoesnotimpacttheEmergencyOperatingProcedureTuesday1 stMarch,2016:19:32,Page102of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONguidancefortheoperators.RemovedResponse,Pg.3581.4.6SSIB:SafetyIssueResolutionBrancha.Round2RAIquestionnumbersbeginwiththenextsequentialnumberfromtheApril15,2014,RAI(Round1)forthissection.b.Follow-upquestionsfromtheSTPNOCresponsestotheRound1RAIquestionsreferbacktotheRound1RAInumberfromthissection unlessotherwisespeci"ed.43.Inquestion2oftheApril15,2014,RAI,thelicenseestatedthatthevaluesforsizedistributionsforthe"brousinsulationaredocu-mentedinReference46.Reference46wasnotincludedinthesubmit-tal.Pleaseprovideasummaryoftherelevantsizeinformationfrom Reference46intheformofatableincludingthesizedistributions withinthepostulatedZOls.

RequiredResponse,Pg.35844.Inquestion4oftheApril15,2014,RAI,thatNRCsreviewindicatesthatitislikelythattheSTPmethodologydiscussedinthe responsemaybeacceptableandmayprovideconservativetransport resultswhenconsideredwithintheprobabilisticframework.However, lowdensity"berglass(LDFG)congestionmaynotbethemetricthat dominatesthelikelihoodofdebrisreachingthestrainerbasedon breaklocation.Althoughtheuseofthesteamgeneratorcompart-menttransportfractionmaybemoderatelyconservativeasclaimed, theNRCwasunabletoverifythisassumption.Itwasalsonot cleartothethatthemeasureof"bercongestionwithinspecif-icallyde"nedvolumesincontainmentprovidethemostimportant measureofdebrisamountsthatmaybegeneratedortheprobability thatdebriswouldbegeneratedwithinthosevolumes.Ifonelocation iscongested,butthe"brousdebrisinthatareacannotbedamagedby abreakitisnotrelevant.Pleaseverifythatthemethodologyresults inoverallrealisticorconservativetransportfractionsconsideringthe possiblebreaklocationsandtheLDFGcongestion.

RequiredResponse,Pg.35945.Forquestion6.a.oftheApril15,2014,RAI,theNRC"ndsthatthelicenseedidnotprovideanadequateresponsetothequestion.

TheDrywellDebrisTransportStudy(DDTS)statesthatifgratings donotcoveranentiretransportpaththattheymaynotbeasef-fectiveindebriscaptureasnotedinthetestmetrics.Simplyusinga ratioofopenareatototalareamaynotprovidearealisticorcon-servativeestimateofdebriscapture.Thegratedareaislikelytohave higherresistanceto"owthatwillincreaseasitcollectsdebris.Debris isgenerallyassumedtobehomogeneouslydistributedthroughoutthe blowdown"ow.Iflessvolumeofblowdownpassesthroughthegrating dueto"owresistance,lessdebrisisavailabletopassthroughorcollect onthegrating.TheNuclearEnergyInstitute(NEI)baselineguidance assumesthatsmall"nesaredebristhatwillpassthroughgratings, sonoholdupofsmallor"ne"brousmaterialisassumedusingbase-linemethodology.Thebaselinefurtherassumessmall"nestobetheTuesday1 stMarch,2016:19:32,Page103of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONbasicconstituentofthedebrisfortransportpurposes.Therewerenore"nementsregardingcreditinggratingstoreducetransportfoundin eitherNEI04-07ortheNRCSEon04-07.Therefore,thelicensee shouldjustifytheassumptionthattheamountofdebriscapturedby gratingsinpathwaysthatarenotfullycoveredcanbeestimatedus-ingasimpleratiooftheopenareatototalarea.Pleaseprovidea justi"cationthatthedebriscapturemetricsusedintheevaluation arerealisticconsideringtheissueidenti"edabove.

RequiredResponse,Pg.36446.Thelicenseesresponsetoquestion7.b.oftheApril15,2014,RAI,statedthatthesigni"cantlylongerwashdownperiodsatSTP,com-paredtothelengthoftheDDTSwashdowntestsareinconsequential totheSTPevaluation.Theconclusionisbasedonaportionofthe NEIguidancedocument,NEI04-07,thatfoundtheerosionof"brous debrisbycontainmentsprayislessthanonepercent.TheRAIaimed attheerosionof"brousdebrisbycontainmentspray,butrequested forclari"cationifthewashdownof"brousdebristhroughgratings wouldincreaseabovethatfoundduringtheDDTSandifthewash-downtimeissigni"cantlyincreased?TheNRCisspeci"cally interestedinthesmall"berwashdowntransportfractionsprovided inTable2.2.23ofVolume3ofthelicenseessubmittaldatedNovem-ber13,2014.Thesevaluesarecurrentlylistedas7-19percentwashed downintheannulusand21-27percentwasheddowninsidethesec-ondaryshieldwall.Thesedonotappeartobe"brouserosionval-ues.Pleaseprovidejusti"cationthatthewashdownvaluesfroma 30-minutetestareapplicabletotheSTPconditionconsideringthe clari"cationprovided.

RequiredResponse,Pg.36747.Inquestion14oftheApril15,2014,RAI,theNRCrequestedthebasisfortheuseof1/16inchasthevaluebelowwhicha"ltering bedisassumednottooccur.Thelicenseesresponsetothequestion isbasedonNRCsacceptanceoftheheadlosscorrelationand asensitivitystudythatshowednochangeinCDFifthecriterion isreducedtozeroinches.Becauseneitherhasbeenacceptedatthis time,theacceptabilityoftheresponsetoRAI14isindeterminate.

Additionally,theuseofa1/16-inchcriterionbelowwhichchemical cannotoccurisnotsupportedbysomeindustryteststhathad 1/16inchof"berorlessadded.Sometestshadmeasurableincreases inheadlosswithlessthan1/16-inchtheoretical"beronthestrainer afterchemicalswereaddedtotheloop.TheNRCagreesthatitis unlikelythataheadlossgreatenoughtoresultinstrainerfailurewill occurwithsuchalow"berload.However,thepotentialforthehead losstoresultin"ashingoradditionaldeaerationwasnotaddressed bythelicensee.Thesensitivitystudywasalsoconductedbeforecor-rectionstopoollevelandcleanstrainerheadloss(CSHL)valueswere implemented.Asstatedabove,theNRChasnotacceptedthe headlosscorrelationusedtoperformthesensitivitystudy.Theli-censeeisrequestedtoproviderevisedresponsetoRAI14considering theinformationdiscussedabove.RemovedResponse,Pg.368Tuesday1 stMarch,2016:19:32,Page104of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION48.Questions15,16,17,18,21,and22oftheApril15,2014,RAI,re-questedadditionalinformationregardingthelicenseesuseofacor-relationtocalculatedebrisheadloss.TheNRChasestablished apositionthatcorrelationsmaynotbeusedtocalculateheadloss unlessthecorrelationisvalidated,underplant-speci"cconditions,for therangeofconditionstowhichtheresultswillbeapplied.Thisposi-tionwasdiscussedwiththelicenseebeforetheformalsubmittal.The NRCdoesnotconsidertheresponsestobeadequatesincethe licenseesuseofcorrelationswerenotvalidatedunderplant-speci"c conditions.Thelicenseeisrequestedtoprovidearevisedresponse consistentwiththeNRCposition.RemovedResponse,Pg.36849.Thelicenseesresponsetoquestion27oftheApril15,2014,RAI,statedthattheuseof0.220ftastheCSHLvaluewasanerror.The licenseeperformedsensitivitystudiestodeterminetheofusingthecorrectvalueof1.952ftonoverallCDF.Thelicenseestatedthat thechangeinCDFwouldbeabout18percentwhenthecorrectvalue isused.ThelicenseealsostatedthatamoreaccurateCSHLvalue wouldbeused.Doesitmeanthat1.952ftisthemoreaccurate valueofCSHL?Ifnot,pleaseprovidethe"moreaccurate"valueof CSHLthatwillbeusedinfuturecalculations.

RequiredResponse,Pg.36950.Thelicenseesresponsetoquestion28oftheApril15,2014,RAI,statedthattheuseofaheadlosscorrelationisessentialtotherisk-informedmethodbecauseitprovidesunderstandingofsubtleinter-actionsbetweenvariableparametersconsideredintheanalysis.How-ever,theneedtoapplya5Xsafetyfactortobounduncertainties inthecorrelationindicatesthatcon"denceinthemethodisrela-tivelylowandthatevaluationofinteractionsbetweentheparameters maybesigni"cantlyskewed.Theserelationshipsmaybefurthermis-characterizedbyresortingtoalimitingpackingfactorforthedebris bed.Theresponseprovidesasensitivitystudyforsafetyfactorvalues aroundthe5Xvalueusedintheevaluation.However,theresponse doesnotprovideabasisforthevaluesusedinthestudy.TheNRC believesthatbecausethereareuncertaintiesinmanyaspectsof themodelandthatmanyofthesearesigni"cant,thatthe5Xmul-tipliermaynotenvelopetheseuncertainties.TheRAIresponsedoes notappeartoaddresstwosigni"cantissues,theuncertaintycausedby non-homogeneousbedsandthelackoftestingtovalidatethemodel forplant-speci"cconditionsthatleadtomodeluncertainty.Other uncertaintiesinherenttotheuseofcorrelationsforheadlossshould alsobeaddressedincludingstatisticaluncertaintiesarisingfromthe useoftestdata,uncertaintiesarisingfromtheuseofthecorrela-tion,anduncertaintiesintroducedbyassumingthattestconditions arerepresentativeoftheplant.Pleaseprovideanevaluationofhow theindividualuncertaintieswithinthemodelareaccountedforand provideanestimateofthetotaluncertaintycreatedbyuseofthe model.RemovedResponse,Pg.36951.Thelicenseesresponsetoquestion31oftheApril15,2014,RAI,Tuesday1 stMarch,2016:19:32,Page105of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONdescribedacalculationthatevaluatesthepotentialforthecollec-tionofgasbubblesintheSTPstrainer.ThelicenseecitesReference 56ofVolume3,TDl-6005-07,VortexAirIngestionandVoidFrac-tionSouthTexasProjectUnits1and2,Revision3,November17, 2008,whichevaluatesthetransportofgasvoidsinthepipingbetween strainerandECCSandCSpumps.Neitheracopyofthereferenced documentnoranyapplicabledetailsfromthereferencewereprovided totheNRCItwasalsonotdescribedhowitwasdetermined thatvoidswouldnotcollectinthestrainer.Pleaseprovideasum-maryoftherelevantsectionsofReference56describinghowitwas determinedthatvoidswouldnotcollectinthepumpsuctionpip-ing.Additionally,pleaseprovideinformationthatevaluateswhether voidscancollectwithinthestrainer,andiftheydo,howthee wasevaluated.

RequiredResponse,Pg.36952.Thelicenseesresponsetoquestion33oftheApril15,2014,RAI,statedthattheCASAGrandemodeloverestimatesthewaterlevel comparedtocomputeraideddesigncalculatedlevels.Thelicensee statedthattheerrorwillbecorrectedsothatfuturesubmittalscon-tainaccuratepoollevels.However,thelicenseealsoneedstoverify thatstrainersubmergenceisadequateandthatvortexing,deaera-tion,and"ashingevaluationsadequatelyre"ectthecorrectedlevels andthattransportisnotduetohigherpoolvelocities.Please provideinformationthatjusti"esthattheseareasarenotadversely RequiredResponse,Pg.37053.Thelicenseesresponsetoquestion34oftheApril15,2014,RAI,statedthattotalCSS"owisdeterminedbymultiplyingtherandom pump"owratebythenumberofoperableCSSpumps.These"ow ratesarerandomlyselectedfrombetweenthemaximumcalculated "owrateandsomeminimumvalue.Itwasnotclearthatusingrandom valuesisappropriateandhowtheminimumvalueswerecalculated.

Thelicenseealsostatedthatforalltwoandthreetraincasesthat CASAusesthehighertwotrain"ow,sinceitisconservative.Theli-censeeincludedreferencetoReference42,Volume3,5N109MB01024, DesignBasisDocumentContainmentSpray,Revision3,November 17,2004.Neitheracopyofthereferenceddocumentnoranyapplica-bledetailsfromthereferencewereprovidedtotheNRCPlease summarizetherelevantinformationfromReference42,providethe methodologyusedtodeterminetheminimum"owrates,orprovide thebasisforusingrandom"owratesforeacheventinsteadofcalcu-latingeventspeci"c"owrates.RemovedResponse,Pg.37054.Thelicenseesresponsetoquestion36oftheApril15,2014,RAI,statesthatstrainerbucklingisthelimitingfailurecriterionwhen comparedtoNPSH.Itwasnotclearthat"ashingwasconsideredas afailuremodeforthestrainerintheSTPsubmittal.Pleasestate how"ashingacrossthestrainerisevaluatedbyCASAGrandesince thisfailuremodemaybemorelimitingthanstrainerbucklingwhen the"uidtemperatureishigh.Forquestion41.c.oftheApril15,Tuesday1 stMarch,2016:19:32,Page106of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATION2014,RAI,theNRChasacceptedtheuseofmitigativemea-surestoaddressdefense-in-depth.Thelicenseecreditedbackwashof thestrainersasamitigativemeasure.However,itwasfurtherstated thatthemitigativemeasuresforbackwashoftheECCSstrainershave notbeenproceduralized.Pleasedescribetheproceduralrequirements thatareinplacetoinitiateECCSstrainerbackwashorrevisethesub-mittaltoremoveitscredit.

RequiredResponse,Pg.37155.Forquestion41.c.oftheApril15,2014,RAI,theNRChasac-ceptedtheuseofmitigativemeasurestoaddressdefense-in-depth.

Thelicenseecreditedbackwashofthestrainersasamitigativemea-sure.However,itwasfurtherstatedthatthemitigativemeasures forbackwashoftheECCSstrainershavenotbeenproceduralized.

Pleasedescribetheproceduralrequirementsthatareinplacetoini-tiateECCSstrainerbackwashorrevisethesubmittaltoremoveits

credit.RequiredResponse,Pg.37255aCASAGrandeusesadistributionforthetemperatureatwhichchemicalareassumedtooccurandadistributionforthe conventionalheadlossbumpupfactor.Volume3statesthat chemicalareassumedtooccurbelow140Fandthattheconventionalheadlossbump-upfactoris5.Pleasestatewhich methodologyisintendedtobeusedandupdatethedocumenta-tionorthemodeltore"ecttheintendedmethodology.RemovedResponse,Pg.37256.CASAGrandedoesnotimplementthebedcompressionaspectsoftheNUREG-6224Correlation.Volume3,equations33-38implythatthe compressionfunctionisimplementedinCASAGrande.TheNRC understandsthatthisissuewasaddressedbyimplementinga limitingbedcompressionforalldebrisheadlosscalculations.Please verifythatthishasbeenaccomplishedandprovideupdatedresults basedontheupdatedmethod.Pleaseprovidethebasisfortheas-sumptionthatthelimitingbedcompressionchosenisappropriate.RemovedResponse,Pg.37257.TheNRChasseveralconcernswiththemodelusedfor"berpenetrationthroughthestrainer.Consideringtheissuesdescribedin thisRAI,theNRCdoesnothavehighlevelofcon"dencethat thedebrispenetrationmodelaccuratelyrepresentstheexpectedde-brispenetrationandin-vessel"beraccumulationthatcouldoccurin theplant.Pleaseprovideinformationthatjusti"esthattheCASA Grandecalculationsfor"berpenetrationaremeaningfulandrepre-senttheplantconditions:(a)Assumptionsandmodelingtechniquesregardingdebrisarrivaltimingand"ltrationmayresultinnon-conservativebypassre-sults.Intheresponsetoquestion6.b.oftheApril15,2014,RAI, thelicenseestatedthatearlyarrivalofdebrisatthestrainerre-sultedinhigher"ltrationandlowertotalbypass.Theresponseto RAI11bstatedthatdebristransportedduringpool"llisplaced directlyonthestrainerattheinitiationoftheLOCA.Thisis alsorelatedtothenon-intuitiveresultsfoundduringasensitiv-itystudyprovidedtotheNRCforreview.TheNRCTuesday1 stMarch,2016:19:32,Page107of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONbelievesthattheresultisnon-intuitivebecauseitisnon-physical.Debrisarrivaltimingshouldnothaveasigni"canton"ltra-tion,ifrealistictimingisused.Theunderstandsthatplacing "beronthestraineratthestartofrecirculationmaybeconser-vativewithrespecttoheadloss,butmaybenon-conservative withrespecttostrainerpenetration.TheNRChasdeter-minedthatassuminghomogeneousmixingof"berinthepoolat thestartofrecirculationratherthanassumingthatsome"ber transportstothestrainerpriortorecirculationislikelytobe moreconservative.TheNRCunderstandingisbasedonthe relativelyshorttimeduringwhichsigni"cantbypassoccursand thelongertimeoverwhichheadlossbecomesmorerisksigni"-

cant.Pleaseprovideinformationthatjusti"estheSTPapproach isconservativeorincorporateamethodologythatismoreappro-

priate.RequiredResponse,Pg.372(b)Iftheexistingmodeloramodelthatresultsinpenetrationbeinghighlydependentonarrivaltimingearlyintheeventismain-tained,pleasejustifywhythemodelisnotmorecorrelatedto theamountofdebrisarrivingatthestrainerregardlessoftim-ing.IfdebrisarrivingatthestrainerattheinitiationoftheLOCA thecalculatedbypassamountpleasejustifythismodelbe-havior.Doesthemodelassumethatearlyarrivingmaterialcan passthroughthestrainer?Ifnot,pleasejustifytheassumption.

Also,pleaseprovidejusti"cationthatlessdebriswouldbypass thestrainerintheplantifdebrisarrivesatthestrainerearlierin thescenario,thatis,themodelaccuratelyre"ectsplantperfor-

mance.RequiredResponse,Pg.372(c)Howaretheuncertaintiesresultingfromapplyingbypasstestresultstotheplantconditionaccountedforinthemodel?Are thereconditionspotentiallypresentintheplantthatwouldresult inmorebypassthanoccurredintherelativelycontrolledtest conditions?Pleaseexplain.

RequiredResponse,Pg.372(d)Howareuncertaintiesassociatedwiththestrainerbypasscalcu-lationaccountedfor?Thecalculationappearstobeverysensi-tivetoarrivaltiming.Also,howareuncertaintiesthatarisefrom testingandthetranslationoftestresultsintobypassmodelsac-countedfor?Pleaseexplain.

RequiredResponse,Pg.373(e)TheNRCnotedthatchangingthetimestepintheCASAGrandedebrispenetrationmodelhasasigni"cantonthe output(amountofdebrisreachingandaccumulatinginthecore).

CASAGrandeusesarelativelyinaccuratemethodtointegrate themassbalanceequationsfordebrisaccumulatedinthecore, especiallyearlyintheaccidentsequenceafterinitiationofrecircu-lation.Pleasedescribehowthelicenseedeterminedthatthetime stepintervalandintegrationmethodprovideappropriateresults (ideally,theconditionalprobabilityoffailurebyexceedanceof thecold-legbreak"berlimitshouldbeindependentofthecom-Tuesday1 stMarch,2016:19:32,Page108of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONputationaltimesteps).

RequiredResponse,Pg.373(f)TheNRCnotedthatoneinputparametertotheCASAGrandecodetocomputethe"ltrationisoneorder ofmagnitudemorethanthatdeterminedbytestinganddoc-umentedinVolume3ofthesubmittal(Table2.2.28,parame-term testtheupperboundis0.00037231/g;insteadavalueof0.0037231/gwasapparentlyusedintheCASAGrandecompu-tationsinsupportoflicensesubmittals).Theresultofthiserroris overestimationofthe"ltration,whichcausesunderesti-mationintheamountof"berpenetrationandin-vesselaccumu-lation.Sensitivitystudiessuggestthatthiserrorwouldunderes-timatethecold-legbreakin-vessel"berlimitfailurecontribution totheCDFbyaboutanorderofmagnitude.Pleaseexplainand includecomparisonsof"ltrationandsheddingrates computedbyMonteCarlosamplingtotestdatainyourresponse.

RequiredResponse,Pg.37458.TheNRCreviewedtherelationshipbetweenbreaksize,andCASAGrandefailurepredictions.Theresultsofthereviewindicate thattheremaybediscontinuitiesintheresultsthatsuggestthat failuresduetocertainbreaksizesarenotpredictedoraremuchless likelytooccurthanwouldbeexpected.Forexampleonebreaksized atabout5inchesresultsinafailure.Withrespecttobreaksize, noadditionalfailuresoccuruntilthebreaksizereachesabout10 inches.Thisbehaviorappearstobenon-physical.Pleasediscussthis observationandprovideanevaluationofwhetherthisbehavior theresultsoftheanalysis.RemovedResponse,Pg.37459.ItistheNRCsunderstandingthatthecomputer-aideddesign(CAD)modelusedtodeterminedebrisgenerationamountswasdevel-opedundera10CFR50,AppendixBprogram,andthereforetreats theoutputtobeaccurate.However,itmaynotbethecaseforthe debrisgenerationvaluesusedinCASAGrande.Pleasedescribethe methodologyusedtoimporttheCADvaluesintoCASAGrandeand provideinformationthatdescribeshowthedebrisgenerationamounts usedbyCASAGrandewerevalidatedtobeaccurate.Pleaseinclude informationthatdemonstrateshowtheinterfacesbetweentheCAD modeloritsinputtoCASAGrandewerevalidatedtobecorrectly implementedanddescribewhetherrawCADvalueswerevalidated tobethesameasthoseusedinCASAGrande.

RequiredResponse,Pg.37560.Section5.4.3ofthesubmittaldatedNovember13,2013,indicatesthatalmost100percentofthebreakscenariosgeneratelessthan10ft 3of"berglassdebris(theprobabilityofgeneratingmorethan10ft 3 issmallerthan10 12).Usingadensityof2.4 lbm ft 3,theequivalentmassof10ft 3of"beris24lbs(10.89kgs).TheNRCreviewoftheCASAGrandeprogramindicatesthattheremaybeasigni"cantnumberof casesthatgeneratemuchmorethan10ft 3of"berglass(hundredsanduptoone-thousandkg).whichappearstoimplythattheprobability ofgeneratingmorethan10.89kgof"berglassissmallerthan10 12 ,andclarifyifthisinformationwasusedintheCASAGrandemodel.Tuesday1 stMarch,2016:19:32,Page109of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONPleaseclarifyiftheinformationinFigure5.4.5inVolume3alsoincludeslatent"ber.

RequiredResponse,Pg.38261.ForbreaksthatarenotDEGBandareassumedtohaveahemi-sphericalZOI,pleaseexplainhowaretherobustbarrierstreated?

Forexample,ifthebreakisonapipenearthe"oorandoccurson thebottomofthepipe,isthepotentialfordamagefromare"ected jetaccountedfor?

RequiredResponse,Pg.38362.Duringreviewofthelicenseesresponsetoquestion9oftheApril15,2014,RAI,theNRCdevelopedanadditionalquestionregarding thetreatmentofdebrisintheheadlosscalculation.Pleaseclarifyif thesmalland"nedebrisaretreatedasiftheyhavethesameproper-tiesintheheadlosscalculation(correlation)?Inyourresponse,please clearlyexplainhoweachdebrissizeistreated?RemovedResponse,Pg.38563.BasedonthelicenseesresponsetoESGBquestion1.b.oftheApril15,2014,RAI,itappearsthatsomelargebreaks,manymedium breaks,andallsmallbreaksdonotgenerateenoughdebristoresult ina1/16-inchbedwhendistributedover3strainertrains.Please providethefollowinginformation:

-Distributionoflowdensity"berglass(LDFG)debrismassreach-ingthestrainersforsmall,medium,andlargebreaksseparately.

-Theamountoflatent"brousdebristhatreachesthestrainersforeachbreakcategoryandifitvaries,providethedistributionand methodologyusedtodeterminetheamounts.

-Therangeofthemassof"ne"brousdebrisandsmallpiece"brousdebrisgeneratedforeachofthebreakcategories.

-Therangeofthemassesofthese"bercategoriesthattransporttothestrainer.

RequiredResponse,Pg.38564.Basedonthereviewofthelicenseesresponsetoquestion2oftheApril15,2014,RAI,thehasidenti"edthefollowingconcern:

whatcausesthevariabilityintheheadlosscalculationperformedby thecorrelation?Forexample,scenariosthatcontainapparentlysim-ilardebrisloads(CASAGrandeCase1intheRAIresponse)may havesigni"cantlytcalculatedheadlosses.Theheadlosses fromthereferencedtestsrepresentCASAGrandevaluesinthe99th percentile,indicatingthatalmostallheadlossespredictedbyCASA Grandearelowerthanthetestresults.ThelimitingCASAGrande Headlosscalculationwas8.2feetforconventionaldebrisand161.9 feetfortotalheadloss,whichismuchhigherthanthetestresults.

Thesemaximumvaluesseemhigherthancouldpossiblyoccur,at leastforthetotalheadloss.Explainifthesemaximumvaluesrealis-ticoraretheynon-physicalpredictions.ExplainwhyCASAGrande predictslowerheadlossesthanthetestresultsover99percentofthe

time.RemovedResponse,Pg.38565.RG1.174statesthatlicenseesareexpectedtoevaluatewhethersuf-"cientsafetymarginswouldbemaintainediftheproposedlicensing basischangeweretobeimplemented.TheNRCrecognizesthatTuesday1 stMarch,2016:19:32,Page110of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONsafetymargincannotbecharacterizedbyasinglenumberforatime-dependentanalysiswithmultiplefailuremodes.Instead,itcanbe representedbyanequationorrelationshipthatrepresentsthesafety marginasafunctionoftimeforeachofthesevenGSl-191failure modes.Forexample,thesafetymarginwithrespecttostrainerme-chanicalcollapsecanberepresentedas:

S m=9.35ftWhere S m=marginwithrespecttostrainermechanicalcollapse=dtialpressureacrossstrainerasafunctionoftimePleasedescribewhetherCASAGrandecalculatessuccesswithre-specttoeachofthesevenGSl-191failuremodesinamannerthat isconsistentwithRG1.174guidanceonsafetymargins.Speci"cally, pleaseidentifythefailurethreshold(worstallowablevalue)foreach failuremodeandstatewhetheritisconsistentwithexistinglicensing basiscalculations.RemovedResponse,Pg.38566.Assumption1jofVolume3statesthatswitchovertohotlegin-jectionwouldoccurbetween5.75and6hoursafterthestartof theevent.Assumption11astatesthecurrentSTPdesignba-sisevaluationmethodologyusedtocalculatetherequiredhotleg switchovertimingisappropriatewiththeexceptionofGSl-191related phenomenon.Whenanalyzingboricacidprecipitationinregardsto post-LOCAlong-termcorecooling,themixingvolumeandpercent-ageofvoidsinthecoreusedintheanalysesneedtobejusti"ed.Im-propermodelingcouldresultinnon-conservativeliquidvolumeafter aLOCA.Ultimately,thiscouldimpactthehot-legswitchovertime inaplantsemergencyoperatingprocedures.STPscalculationfor hot-legswitchovertimefollowingaLOCA(NC-7136,Revision1)was providedinresponsetoSNPBRAI4.Aninputforthiscalculation isliquidvolumeintheRCS.Pleaseprovidethemixingvolumeand percentageofvoidsinthecoreforSTPlicensingbasiscalculations usedtodeterminetheliquidvolumeintheRCSforhotlegswitchover timinginthecalculationtovalidateassumptions1jand11a.Please justifytheuseofthesenumbersandanyassumptionsmade.The licenseecanrefertoNRC-approvedmethods,asappropriate.

RequiredResponse,Pg.3861.4.7STSBTechnicalSpeci"cationBranch4.

Background:

InresponsetoNRCcomment/question2.4(page6of179,Volume6.2),thelicenseestatedthefollowing:Adescriptionofhowtheproposedchangewillctthetechnicalspeci"cationsisprovidedinRegulatoryEvaluation Section4.1.3intheLARprovidedinEnclosure3.Asdis-cussedinmoredetailinEnclosure3,nochangestooper-abilityrequirementsforctedsystemsandnochangesto theexistingtechnicalspeci"cationActionStatementsarepro-posed.Proposedchangestothetechnicalspeci"cationbasesTuesday1 stMarch,2016:19:32,Page111of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONthatconformtothechangesinthelicensinganddesignbasesareincludedinAttachment3toEnclosure3forinfor-

mation.Page1of1ofAttachment3toEnclosure3ofthelicenseeslet-terdatedNovember13,2013,TechnicalSpeci"cationsBasesPage Markups,states,inpart:UFSARAppendix6Aprovidesarisk-informedapproachthataddressesthepotentialofdebrisblockageconcludingthat long-termcorecoolingfollowingadesignbasislossofcoolant accidentisassuredwithhighprobability.UFSARAppendix 6Aalsoprovidesguidanceforassessingthepotentialimpact onOperabilityduetounexpectedmaterialsuchasloosede-brisdiscoveredincontainmentthatmaycontributetodebris loadingonthestrainers.Page15of16ofAttachment2toEnclosure3ofthelicenseesletterdatedNovember13,2013,"STPEGSUFSARPageMarkups"states, inpart,thefollowing:Thetableprovidesguidancethatmaybeusedtoimmedi-atelyassessthepotentialimpactduetounexpectedmaterial discoveredincontainmentthatmaycontributetodebrisload-ingonthestrainers.AsdiscussedinReference6A-4[licensee letterdatedJune19,2013],thesevaluesarenotnecessarily thelimitingamountofeachtypeasanalyzed.Conservatisms inthereportedvaluesarealsodiscussedinReference6A-2

[licenseeletterdatedDecember11,2008].Therefore,acon-ditionthatmayexceedthevaluesshowninthetabledoesnotprecludereasonableexpectationofoperability.DebrisTypeInputParameterValueMinimum(Reference6A-6)MarginLatentdebris,consistingof:200lbm(Total)40lbm(Total)

• Dirtand/ordust170lbm(1.0cubicft)34lbm(0.2cubicft)

• Fiber,e.g.,"brousinsulation100sq-ft6lbm(2.5cubicft)Miscellaneousdebris,includingbutnotlimitedtounquali"edtagsandlabels100sq-ft10sq-ftUnquali"edcoatingsTable6.1-4100sq-ftPage26of31ofEnclosure3toaletterfromSTPdatedNovember13,2013,states,inpart,thefollowing:Whenwarranted,animmediateoperabilitydeterminationwillbefollowedbyapromptoperabilitydeterminationthat willapplyadditionalinformationandsupportinganalyses tocon"rmtheimmediateoperabilitydetermination.Evalu-ationsmayconsideradditionalinformationprovidedinthe inputstotheCASAGrandeanalysisaswellastheiden-ti"edconservatismsassociatedwiththecategoriesofmajor assumptionsintheCASAGrandeanalysis,Section3ofVol-ume3(Enclosure4-3).Tuesday1 stMarch,2016:19:32,Page112of393 DRAFTPART1.NRCREQUESTSFORADDITIONALINFORMATIONForadiscoveredconditionthatpotentiallyctsdebrisquantitiesincontainment,theapplicableCASAGrandein-putparametersandassumptionsprovideameansforimmedi-ateoperabilitydeterminationsandfollow-updeterminations, aswarranted,toevaluatetheimpactoncontainmentsump performance.

Concern:ItistheNRCspositionthatwhenevaluatingoperabil-ityofanSSC,theuseofriskassessmentorprobabilitiesofoccurrence ofaccidentsoreventsisunacceptable.Thede"nitionofoperability isthattheSSCsmustbecapableofperformingtheirspeci"edsafety functionorfunctions.Thisinherentlyassumesthattheeventoccurs andthatthesafetyfunctionorfunctionscanbeperformed.Oper-abilityisnotindeterminate.AnSSCrequiredtobeoperablemustbeabletoperformitsspeci"edsafetyfunctionoritisinoperable.TheNRCisconcernedthattheCASAGrandedesigninputs(parametersandassumptions)referredtoinReference6A-5ofthe UFSARMarkupincludesprobabilityaspectsthelicenseeproposes tobeacceptabletobeusedduringanoperabilitydeterminationif aconditionisdiscoveredthatpotentiallydebrisquantitiesin containmentandtheneedarisesforevaluatingtheimpactoncon-tainmentsumpperformance.

Request:providethefollowingadditionalinformation:1)AnexplanationofhowtheassumptionsreferredtoinReference6A-5oftheUFSARMarkupanddiscussedinSection2.2ofVol-ume3ofthesamedocumentwillbeusedduringanoperability determination.Pleaseincludeanexampletotheextentpractical.2)Ifthelicenseeisproposingtoallowtheuseofriskinformationintheassessmentofoperability,then:a.Pleaseprovideadescriptiondemonstratingtherelationshipbetweenprobabilityandoperabilityforeachoftheassump-tionsdiscussedinSection2.2ofVolume3.b.PleaseexplainhowwouldtheprobabilityofoccurrenceofeachoftheassumptionsdiscussedinSection2.2ofVolume 3changetoimproveordegradetheimpactoncontainmentsumpperformance.

RequiredResponse,Pg.388Tuesday1 stMarch,2016:19:32,Page113of393 DRAFTPart2RAIResponses(Round1)2.1ML14149A434,Firstsetofresponses2.1.1APLABResponses2.1.1.1APLAB,CASAGrande,LOCAFrequencies:Question1 STPResponseto1a,(Item1a,Page36)Doublecountingofannualfrequencyforanybreaksizeisexplicitlyprevented bythehybridmethodologythatpreservestheexceedancefrequencydistribu-tionsfromNUREG-1829.Althoughthetotalfrequenciesarepreservedforany breaksizegiveninNUREG1829,therebypreventing"doublecounting",the frequenciesatanyspeci"cweldlocationwereweightedaccordingtothedegra-dationmechanismsasdescribedintheLAREnclosure4-3,Section5.3.Bythis method,locationsexposedtomoredegradationmechanismsareappropriately assignedagreaterfractionofthetotalfrequency(forthatbreaksize).STPResponseto1b,(Item1b,Page37)TheexceedancefrequenciesgiveninNUREG1829thatincludenon-pipingcom-ponentcontributionwerepreservedandthereforecontributionsfromnon-piping componentswereincludedintheanalysis.Debris-relatedriskfromnon-pipingcontributorswasexaminedfromtwoper-spectives:(1)potentialfordebrisformation,and(2)proximityofnearbywelds.

Potentialfordebrisformationisbyboththepotentialmagnitudeofthe breakandbytheproximityofinsulationtargets.Forexample,ReactorCoolant Pump(RCP)sealleakswerejudgedtobecomparabletoSBLOCAintermsof potentialforgeneratinginsulationdebrisinthevicinityoftheRCP.Pressur-izerReliefTank(PRT)reliefvalveopeningwasjudgedtohavehigherdamage potentialbutverylittlecollocatedinsulationthatcanbedamaged.Becauseoverallinitiatingeventfrequenciesarepreserved,itismostimpor-tantthatpipeweldsofcomparablesizetothenon-pipingcontributorsarelocated inthesameproximityasthenon-weldcontributorsofinterest.Weldsonlarge pipesareassignedafullrangeofbreaksizes,sotheyprovidesuitablesurrogate coordinatesforotherruptureeventsthatmayoccurinthesamevicinity.For example,the"rstweldonhotandcoldleglinesrepresentsastlocation forreactornozzlerupture.The775weldsconsideredinthepipebasedLOCAfrequencyanalysisare"nelydistributedoverallthelocationsinthecontainmentwheresigni"cant debrisgenerationisexpected.Non-pipingcomponentsthatmaycontributeto aLOCAincludenozzles,componentbodies,pressurizerheatersleeves,man 114 DRAFTPART2.RAIRESPONSES(ROUND1)ways,controlroddrivemechanismpenetrations,safetyandreliefvalves,reactorcoolantpumpseals,reactorvessel,pressurizervessel,steamgeneratorvessels, weldedcapsonretiredlinesandothercomponents.Withtheexceptionofnon-pipecomponentsthatarelocatedinthereactorcavity,allthesenon-pipecomponentsarelocatedatornearpipewelds.For exampletherearemanyweldlocationsinlinesaroundthepressurizervesselin-cludingthesurgeline,spraylines,andthesafetyandreliefvalvelinesthatwould beavailabletosimulatenon-pipecomponentsinthatareaofthecontainment.

Inadditiontherearemanyweldsdistributedalongthecoldlegsincludingthose nearthereactorcoolantpumpsthatwouldsimulatenon-weldlocationsinthose areas.Themodeledweldsthatarelocatedatthesafeendsofthenozzlesatthe reactorvessel,pressurizervessel,andsteamgeneratorvesselarereasonablyclose totheassociatednozzleweldsandarecloseenoughtothevesselstoproducea signi"cantdebris"eldfromtheinsulationaroundthosevessels.Onecategoryof non-pipecontributionstoLOCAfrequencythatisnotlocatednearamodeled weldlocationwouldbethatassociatedwithnon-pipecomponentsassociated withthereactorvessellocatedawayfromthehotlegandcoldlegnozzles,e.g.controlroddrivepenetrations,manways,andinstrumentlinesconnectedtothe reactorvessel.Howeverthesearelocatedinthereactorcavitywhichwasnot foundtobeanimportantlocationforgeneratingatransportabledebris"eld.2.1.1.2APLAB,CASAGrande,LOCAFrequencies:Question3 STPResponse(Item3,Page37)Thebinsizesaredeterminedbythefollowingstepsforeachweldcase:1.InterpolatetheCCDFofbreak-sizefrequencyto"ndtheexceedancefre-quencycorrespondingtoeachLOCAcategorylimit(0.5in.,2in.,6in.).2.DivideintologarithmicallyequalbinstheexceedancefrequencyintervalforeachLOCAcategoryusingthenumberofbinsdeterminedforeach LOCAcategory.3.Invertthelogarithmicbinintervalsbyinterpolationto"ndthecorrespond-ingbreaksizeintervals.Asanexample,Equation25andEquation26ofLAREncl.4-3(Pg.150)canbeusedto"ndthenumberofsmallandmediumbreakswithauserspeci"ed numberof10largebreaks(NL)andamaximumpipediameterincontainment of31.5inches.SolvingEquations25and26forthenumberofsmall(Ns)and mediumbreaks(NM)yieldsNs=landNM=2,respectively.Figure5.3.4shows thatthenumberofbreaksforsmall,medium,andlargebreakshavebeendis-tributedequallyinthelogofexceedancefrequency(yaxisofplot)withintheir respectiveLOCAsizecategory.Usingequallogarithmicspacingcreatesnonuniformprobabilityweightsthatmustbecarriedwitheachsampledbreaksize.Usingequallogarithmicspacing tosamplearapidlydecliningCCDFalsoforcessamplestooccurintheupper endofeachLOCAcategorythatwouldotherwisehaveaverysmallprobability ofbeingselected.Tuesday1 stMarch,2016:19:32,Page115of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.1.3APLAB,CASAGrande,LOCAFrequencies:Question4STPResponse(Item4,Page37)Reference8toEnclosure4-3wasprovidedincorrespondencedatedDecember 23,2013(ML14015A311).Reference7wasprovidedtotheNRCinsupportofameetingonOctober3,2011,andisavailableinNRCsAgencywideDocumentsAccessandManagement System(ADAMS)viaAccessionNumberML112770237.DetailsregardingapplicationofthedocumentsaregiveninEnclosure1tothisattachment.2.1.1.4APLAB,CASAGrande,toPRAInterface-General:Ques-tion1aSTPResponse:(Item1a,Page38)Failuremechanism4,Debrispenetrationexceedsex-vesselelimitscausingavarietyofpotentialequipmentandcomponentfailuresduetowearor clogging,wasaddressedbyareviewofSTPNOCsdeterministicevaluationof thephenomena.TheEx-vesseleDownstreamevaluationwaspreviouslyprovidedinSTPLetterNOC-AE-08002372,Supplement4totheResponsetoGeneric Letter2004-02,datedDecember11,2008(ML083520326).Ex-vesseldownstreamwerereviewedforadequacyundertherisk-informedapplication,andnoadditionalorunusualSTP-speci"cvulnerabilities toex-vesselewereidenti"ed.Reviewofthedeterministicex-vessele analysiswasperformedtoaddresstherequirementsofRG1.174intermsof potentialtotheplantlicensingbasis.FailureMechanism6,Buildupofoxides,crud,LOCA-generateddebris,andchemicalprecipitatesonfuelcladdingexceedsthelimitsforheattransferre-sultinginunacceptablyhighpeakcladdingtemperatures,wasnotexcluded fromtheriskassessment.IntheSTPLARanalysisofex-vesseleoxides, crud,LOCA-generateddebris,andchemicalprecipitateswerenotmodeledas explicitlyasotherphenomenology.However,anestimateofcrudreleaseduring aLOCAtransientwasintroducedasaparticulatesourcethataccumulatesin thedebrisbedandheadloss.TheSTPLARusedanindustrynominal crudreleaseinventoryof24Ibm.Intherisk-informedcontext,ECCSfailuresinitiatedbymechanisms4and6arejudgedtobelessprobablethanthemostunlikelyinitiatorsthatarecon-sideredinthestudy(ex.LBLOCA).2.1.1.5APLAB,CASAGrande,toPRAInterface-General:Ques-tion1bSTPResponse:(Item1b,Page38)OtherfailuremechanismsandassumptionsrelatedtoGSI-191phenomenathatrelyondeterministicacceptancecriteriawereincludedaspointvaluesand werenotvariedacrossphysicallyplausiblerangesincluding,butnotlimitedto:1.ZOIsize 2.LatentdebrisquantitiesTuesday1 stMarch,2016:19:32,Page116of393 DRAFTPART2.RAIRESPONSES(ROUND1)3.Core"berlimitsrelatedtoboron,4.NPSHassumptionsAlthoughthesevalueshavebeenusedasindividualfactorsinpreviouslysubmitteddeterministicanalyses,theywereincluded,andareconsideredfor theirpotentialriskimpact.2.1.1.6APLAB,CASAGrande,toPRAInterface-General:Ques-tion3STPResponse:(Item3,Page38)Section9ofEnclosure4-2toReference1ofthecoverletter(i.e.,Volume2)describeswhatismeantbythefrequencyofsuccessfulpumpcombinationstates andpresentsthefrequenciesforeachstate.Brie"y,thesefrequenciesareforthe sumofmediumandlargeLOCAsequencesrequiringsumprecirculation,also foundnottoresultincoredamageintheabsenceofGSI-191phenomena,and eachfrequencyisforanexclusivecombinationforthenumberofECCSpumps running.ThefrequenciesinthePumpStateFrequencycolumnofTable2.2.11 comedirectlyfromcolumn2ofTable9-1inVolume2,thoughtheyareresorted bythenumberofpumpsworkingratherthanbythefrequencyofeachpump state,asinTable9-1ofVolume2.TheprobabilitiesfortheoccurrenceofthetGSI-191phenomenacienttocausefailurearederivedbyCASAGrandeseparatelyfordtECCS pumpcombinationstates.Onlythehighestfrequencyrankedpumpcombina-tionstateswereevaluatedsincethosearetheoneswiththegreatestpotential toincreasecoredamagefrequency.Forexample,thereisnoneedtoevaluate pumpcombinationstateswherethelowpressureinjectionpumpsallfailsince suchcombinationsalreadyleadstocoredamage,independentoftheGSI-191 phenomena.ThePRAmodelsapplytheseprobabilitiesalongeachsequencein thePRAmodeltodeterminethefrequencyofsequencesresultingincoredam-ageduetoGSI-191phenomena.ThePRAmodelsdonotusethefrequencies ofthesestates;ratherthefrequenciesareonlyusedtodeterminewhichpump combinationstatestobeevaluatedbyCASAGrande.Fivepumpstateswere analyzedinCASAGrande.ForthosesuccessfulpumpstatecombinationsnotevaluatedbyCASAGrande,thePRAconservativelyassumedthatallcorrespondingsequencesthenleadto coredamagewithprobability1duetoGSI-191phenomena.2.1.1.7APLAB,CASAGrande,toPRAInterface-General:Ques-tion4aSTPResponse:(Item4a,Page39)Yes,theprobabilitiesofvariousdebris-relatedfailuremechanismsareentforscenarioswheresomecontainmentsystemsdonotoperateasassumed.

However,nocreditistakenintheanalysisforcontainmentpressureaboveva-porsaturation,solackofcontainmentisolationdoesnottheconditional probabilityofECCSfailurecalculatedbyCASAGrande.ConditionalprobabilityofECCSfailuredependsonsumptemperaturehis-toriesthatarebycontainmentsystemperformance.Thermalhydraulic analyses(LAREncl.4-3,Ref.5)havefocusedonnominalcontainmentoperatingTuesday1 stMarch,2016:19:32,Page117of393 DRAFTPART2.RAIRESPONSES(ROUND1)conditions,butsomecontainmentfailurestateshavebeenassessed.ConditionalprobabilityofECCSfailureunderdegradedcontainmentsystemperformance isinherentlytfromtheconditionalprobabilityofECCSfailureunder nominalconditionsbecauseoftheequipmentfailurefrequenciesthatareintro-duced.ConditionalprobabilityofECCSfailureunderdegradedconditionscan alsovarybecauseofphenomenologicaldependenceontemperature,including chemicalcorrosionandprecipitation,NPSHAvailable,anddegasi"cationpoten-

tial.Currentanalysesassumeasinglerepresentativetemperaturehistoryforsmallandmediumbreaksandasinglerepresentativetemperaturehistoryforlarge breaks,allcomputedfornominaloperatingconditions(LAREncl.4-3,Figure 2.2.1,Pg.46).Thisapproachimplicitlyassumesthattheoccurrencefrequency foralternatetemperaturehistoriesisverysmall.ThePRAcanprovideabasis forweightingthefrequencyofcontainmentequipmentfailureinmuchthesame waythatthePRAprovidesabasisforweightingthefrequencyofpumpfailure states,buttheweightassociatedwithcomplexcombinationsofequipmentfailure rapidlydeclines(LAREncl.4-2,Section10).2.1.1.8APLAB,CASAGrande,toPRAInterface-General:Ques-tion4bSTPResponse:(Item4b,Page39)PotentialinECCSfailureprobabilitycausedbycontainmentsys-temfailurestatesarenotaddressedexplicitlyinthePRAbecausethePRA modelconsiderstheprobabilityofcontainmentsystemfailuresindependentof thesumpfailureprobabilitiesgeneratedbyCASAGrande;i.e.,thesystemfailure probabilitiesarenotmodi"edbasedonanyGSI-191relatedeTheprob-abilityofcontainmentisolationorfancoolersuccessisnotbyGSI-191 phenomena.Section10ofVolume2(LAREncl.4-2)describestheresultsofsen-sitivityanalysistojustifytheapproachassumed.Tosummarizethatdiscussion; thefrequencyofmediumorlargebreakLOCAswithdegradedcontainmentsys-temstates,andwhichavoidcoredamage,isverylow.SinceGSI-191phenomena canonlyincreasecoredamagebymovingaportionofthesesuccesssequences tocoredamage,thecontributionofsuchsequenceswithdegradedcontainment systemstothetotalGSI-191phenomenaimpactisevensmaller.2.1.1.9APLAB,CASAGrande,toPRAInterface-General:Ques-tion4cSTPResponse:(Item4c,Page39)Thedtcontainmentfailuremodesreferredtoinhigh-levelrequirementHLRLE-EarethoselistedinTable2-2.8-9ofTheASMEPRAStandard.The STPPRAisafullLevel1-Level2studythatalsoevaluateslargeearlyrelease frequencyconsistentwiththeTheASMEPRAStandard.Theactivecontain-mentsystemfailuresarefullyrepresentedintheSTPPRAasarethephenomena requiredbyTable2-2.8-9.WhiletheanalysisinCASAGrandeassumedsuccess oftheactivecontainmentsystemsforpurposesofcomputingtheconditional probabilitiesoffailinganyofthe7failuremodesofGSI-191,theSTPPRAcon-sideredallsuchfailures.IfinagivenPRAsequence,theGSI-191phenomena ledtothefailureofsumprecirculation,thisimpactwasaccountedforintheTuesday1 stMarch,2016:19:32,Page118of393 DRAFTPART2.RAIRESPONSES(ROUND1)performanceofcontainmentsprayrecirculationwhendeterminingthesequenceLevel2endstates.TheGSI-191phenomenahavenoimpactontheprobabilities ofsuccessfulfancooleroperation,norofcontainmentisolation.2.1.1.10APLAB,CASAGrande,toPRAInterface-General:Ques-tion5STPResponse:(Item5,Page39)ItwasnotconcludedthatonlymediumandlargeLOCAswouldrequiresumprecirculation.ItwasconcludedthatonlymediumandlargeLOCAswouldboth requiresumprecirculationandpotentiallybebyGSI-191phenomena.

SmallLOCAswhichalsorequirerecirculationaremuchlesslikelytobe becausetheamountofdislodgeddebrisismuchlessandcontainmentspray isnotautomaticallyactuatedforsuchscenarios.Containmentsprayisneeded totransportthecontainmentlatentdebrisandanydislodgedinsulationtothe

sump.SincetheinitialpreparationofVolume2(LAREncl.4-2),ithasbeencon-"rmedthatonlylargeLOCAscenariosareabletochallengeECCSperformance metricsatSTPasshowninFigure1.ECCSperformancemetricsaddressphysi-calphenomenaassociatedwithdebris-inducedon(1)strainermechanical buckling,(2)NPSHmargin,(3)degasi"cation,(4)core"berinventoryassoci-atedwithblockageforhotlegandcoldlegbreaksand(5)core"berinventory associatedwithonsetofboronprecipitationforhotlegandcoldlegbreaks.None oftheuser-speci"edthresholdsfortheseperformancemetricsarechallengedby smallandmediumbreakscenariosatSTP.Becausetransportfractionsandfailed coatingssourcesarelargelyconstantforallscenarios,successfulperformanceof smallandmediumbreakscenariosisattributedtosmallerinsulationdebrisvol-ume.LAREncl.4-3(Volume3)Assumption1ic,page82of248correctlystates thatboronprecipitationfailureswerenotexplicitlyprecludedforsmallbreaks (eithercoldlegorhotleg),andinfact,werenotprecludedforanycoldleg breaks.LAREncl.4-3Assumption11dstatesthatmediumandlarge,andin factall,hotlegbreakswereprecludedfromboronprecipitation.Assumption 11dcontributestothesuccessstatesofsmallandmediumbreaks,butdoesnot overridethedominantconsiderationofsmallerdebrisvolume.2.1.1.11APLAB,CASAGrande,toPRAInterface-General:Ques-tion6aSTPResponse:(Item6a,Page40)Fifteen(15)samplesofthebreakfrequencyvs.sizecurvesweregeneratedforeachpumpstateanalyzedintheSTPstudy.Theinconsistencyinthedoc-umentsectionshasbeenenteredintheSTPcorrectiveactionprogramtotrack correctionforfuturesubmittals.2.1.1.12APLAB,CASAGrande,toPRAInterface-General:Ques-tion6bSTPResponse:(Item6b,Page40)TablessuchasTable6.2ofLAREncl.4-3werepassedtothePRAforeachofthe"veplantfailurestates.ThetablesaregeneratedasstandardCASAGrande outputwiththenames:Tuesday1 stMarch,2016:19:32,Page119of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:ECCSsuccess(green)andfailure(red)asafunctionofbreaksize.BluedashedlinesmarkthesmallestbreakthatcanchallengeECCSperformancemetrics andthelargestbreakthatcanpassECCSperformancemetrics.DistOfCondBlockFailProbDistOfConBoronFailProb DistOfConSumpFailProb DistOfConTotalFailProbTheycontainindependentpointestimatesofmeanfailureprobability(un-sorted)andtheweightsassociatedwitheachsamplefromthetruncatedJohnson uncertaintyenvelopede"nedforannualfrequencyasafunctionofbreaksize.2.1.1.13APLAB,CASAGrande,toPRAInterface-General:Ques-tion6cSTPResponse:(Item6c,Page40)Thestatementonpage84ofVolume2(LAREncl.4-2)iscarriedoverfromanearlierdraftoftheanalysiswhere5pointswereusedtorepresentthe failureprobabilitydistributionsfortopeventsSUMP,FBLK,andBORON.The LARcalculationisbasedon15pointsasdescribedinSection6ofVolume 3(LAREncl.4-3)foreachofthesethreetopevents.TheVolume2statement shouldread:"Theuncertaintyinthesefailureprobabilitiesisreportedasdiscrete probabilitydistributionswith15pointseach."Asnotedabove,thishasbeen enteredintheSTPcorrectiveactionprogramtotrackforcorrectioninfuture

submittals.2.1.1.14APLAB,STPPRAModel-HumanReliabilityAnalysis:Question1STPResponse:(Item1,Page42)IntheSTPPRA,isolablesmallLOCAsreferstothesetofsmallLOCAsoriginatinginthepressurizerPowerOperatedReliefValve(PORV)lineswhichTuesday1 stMarch,2016:19:32,Page120of393 DRAFTPART2.RAIRESPONSES(ROUND1)canbeisolatedbyclosingtheassociatedPORVblockvalve.Thefrequencyofsucheventsistakentobe9.2E-4peryear.Sincethetimeavailableforactionand thepowernecessarytoclosetheblockvalveisdependentonthefullscenario, creditforisolationoftheLOCAbyclosingofthePORVblockvalveisonlytaken attheendofthesequence.TheoperatoractiontoclosethePORVblockvalveis assignedahumanerrorprobabilityof1.58E-5,butitisonlyappliedwhenpower isavailabletotheblockvalveandhighpressureinjectionissuccessfulallowing nearly10hoursbeforeRefuelingWaterStorageTank(RWST)depletionfora successfulresponse.Assumption3.cinVolume3couldbebetterstatedtosaythatifleftuniso-lated,isolableLOCAsmayrequiresumprecirculation.Creditingisolation,how-ever,wouldgreatlylowerthefrequencyoftheisolableLOCAsequencesrequiring sumprecirculation.SincetheisolableLOCAsoriginateinthepressurizerPORV line(typicallyasleakagepastthePORVsthemselves),theydischargetothe PressurizerReliefTank(PRT).Therefore,theyarenotexpectedtodislodge appreciabledebris,andbybeingwithinthesmallLOCAsize,theywouldnot actuatecontainmentspray.Thecombinationofbeingittogeneratea sprayactuationsignalandnotdislodginganyappreciabledebrisisthebasisfor notconsideringisolableLOCAsfurther.2.1.1.15APLAB,STPPRAModel-HumanReliabilityAnalysis:Question2STPResponse:(Item2,Page43)CASAGrandedoesnotcurrentlyconsiderthepotentialforthenumberofrunningpumpstochangebasedonindicationsofdebrisbuildup.Theonly changeinpumpstatuscurrentlyaddressedissecuringspraysaccordingtothe EmergencyOperatingProcedures(EOP).2.1.1.16APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4aSTPResponse:(Item4a,Page43)AtableoftheprobabilitiesoffailingtopeventBORONandtheassociatedstatusofbreaksize,breaklocation,statusofhotlegrecirculationswitchover, andECCSpumpstatesisprovidedbelow.Thenumberofhighheadpumps, lowheadpumps,andspraypumpsoperatingineachpumpstateisindicated.

TheCASAGranderesultsaccountforthelocationofthebreak(i.e.,hotorcold leg)whendeterminingtheprobabilityofcore"owblockageforagivenbreak size.TheCASAGranderesultsareuseddirectlyforthesplitfractionsoftop eventBORONwhenhotlegrecirculationswitchoverissuccessful;asitssuccess precludesexcessiveboronprecipitationatlatertimes.Whenalignmentforhot legrecirculationfails,excessiveboronprecipitationleadingtocore"owblockage isassumedtoleadtocoredamagefortheproportionofbreakslocatedinthe coldlegs.Thecoldlegproportionsofthebreaksizeareasdeterminedinthe samplingwithinCASAGrande;i.e.,0.381forMediumLOCAsand0.256for LargeLOCAs.

SplitFraction IDSplitFractionValue-ProbabilityofCore FlowBlockageBreakSizeStatusofHotLegRecircu-

lationBreakLocation (Cold/Hot)

Applicable Pump State(s)BORML0.381MediumFailed0.381coldlegfractionfor MediumLOCAsAllpump statescontinuednextpage...Tuesday1 stMarch,2016:19:32,Page121of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued SplitFraction IDSplitFractionValue-ProbabilityofCoreFlowBlockageBreakSizeStatusofHotLegRecircu-lationBreakLocation (Cold/Hot)

Applicable Pump State(s)BORLL0.256MediumFailed0.256coldlegfractionforLarge LOCAsAllpump statesBML1S0MediumSuccessCASAresultforpumpstate1Pumpstate1:H3L3S3BML9S0LargeSuccessCASAresultforpumpstate9Pumpstate9:H3L1S3BML22S0MediumSuccessCASAresultforpumpstate22Pumpstate22:H2L2S2BML26S0MediumSuccessCASAresultforpumpstate26Pumpstate26:H2L1S2BML43S0MediumSuccessCASAresultforpumpstate43Pumpstate 43BLL1S1.25X10 3LargeSuccessCASAresultforpumpstate1, considersfraction incoldlegPumpstate1:H3L3S3BLL9S1.04X10 5LargeSuccessCASAresultforpumpstate9, considersfraction incoldlegPumpstate9:H3L1S3BLL22S2.54X10 4LargeSuccessCASAresultforpumpstate22, considersfraction incoldlegPumpstate22:H2L2S2BLL26S3.07X10 4LargeSuccessCASAresultforpumpstate26, considersfraction incoldlegPumpstate26:H2L1S2BLL43S1.04X10 5LargeSuccessCASAresultforpumpstate43,considersfractionincoldlegPumpstate 43BMLGF0.381MediumEither0.381coldlegfractionfor MediumLOCAsAllother pump statesBLLGF0.256LargeEither0.256coldlegfractionforLarge

LOCAsAllother pump states2.1.1.17APLAB,STPPRAModel-HumanReliabilityAnalysis:Question4bSTPResponse:(Item4b,Page44)Forreference,Generalassumption1.jfromVolume3states:Itwasassumedthatswitchovertohotleginjectionwouldoccurbetween5.75and6hoursafter thestartoftheevent.Thisisareasonableassumptionsincetheswitchover procedureisstarted5.5hoursafterthestartoftheeventandtimingofEOP stepcompletion,switchoverforbothtrainscanbecompletedwithin15minutes.Thehumanerrorprobabilityfortheactiontoswitchoverforhotlegrecircu-lationisrepresentedbydatavariableHEHLR.Reference1documentsthequan-ti"cationofthishumanerrorprobability.ThehumanreliabilityanalysisassumesTuesday1 stMarch,2016:19:32,Page122of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatthescenarioresultsfromaLargeLOCA.IfRCSpressureremainsabove415psigbythetimetheoperatorsreachstep21ofOPOP05-EO-EO10Rev.22, thentheoperatorswouldinsteadtransfertoOPOP05-EO-ES12,POSTLOCA COOLDOWNANDDEPRESSURIZATION.However,forthelargerLOCAs, theinitiationofHotLegRecirculationiscuedfromOPOP05-EO-EO10Rev.

22,Step28whichproceduredirectstheoperatorstogoto0POP05-EO-ES14, TRANSFERTOHOTLEGRECIRCULATION,at5.5hours.Theoperators aredirectedtotransfertheHighHeadSafetyInjection(HHSI)tohotlegrecircu-lationbyenergizeandopenaHHSIhotleginjectionMOVandthenclosingthe HHSIcoldleginjectionvalve.TheprocedurethenalignstheLowHeadSafety Injection(LHSI)bylocallyenergizeaLHSIcoldleginjectionMOV(redundant stepisinOPOP05-EO-EO10step27),energizeandopenaLHSIhotleginjec-tionMOVfromtheControlRoom,andthenalsofromthecontrolroomclose theLHSIcoldleginjectionMOV.AcautionatthebeginningofOPOP05-EO-ES14directsthatoneSItrainistoremainalignedforcoldlegrecirculationin casetheLOCAwasaruptureofanRCShotleg.AllremainingSItrainsare tobealignedforhotlegrecirculation.TheEPRIHRACalculatorwasusedto computeatotalHEPforthisactionof3.6x10-5asdocumentedinReference 1.Bothcognitiveandexecutionerrorswereconsideredintheassessment.The timeavailableforactionfollowingthecuewasassumedtobe2hours,although theexpectedtimetocompletionisjust15minutes.Creditwastakenforaction recoverybytheemergencyresponseorganizationsincetheactionwouldtake placewellafter1hourfromthestartoftheaccident.OnlyoneHEPwasfoundnecessarytoaccountforthefactorsnoted.Eachofthesefactorsisdiscussedbelow.LOCAsize-ThisactionisonlyrequiredforthelargerbreakLOCAs;i.e.,forMediumandLargeLOCAs.ItisnotrequiredforSmallLOCAsbecausetheRCS pressurewouldremainabove415psig.Theinitiationcueandtimeavailablefor actionisnotdependentonthespeci"cbreaksizesojustoneactionwasassessed.Plantcon"guration(e.g.,numberofpumpsavailable)-Theproceduralguid-ancedirectinghotlegrecirculationswitchoverisonlypartlydependentonthe numberofpumpsavailable.IfonlyonetrainoftheLHSIpumpsisoperatingin thecoldlegrecirculationmodeat5.5hoursafteraccidentinitiation,thenhotleg recirculationswitchoverwasassumedfailed.Thisisconsistentwiththecaution inOPOP5-EO-ES14,TRANSFERTOHOTLEGRECIRCULATION.Ifmulti-pleLHSIpumpsareoperatingincoldlegrecirculationmode,thenallbutoneis creditedincompletingthetransfertohotlegrecirculationtoanRCSloopthat remainsintact.Tosimplifytheanalysis,themodelassumesthattheoperators preferentiallytransfertohotlegrecirculationusingTrainsAandthenB,never transferringTrainC.TheaccidentsequencekeepstrackoftheRCSloopwith thebreakthoughthisknowledgeisassumednotavailabletotheoperators;i.e.,

themodelallowstheoperatorstoalignanLHSIpumptoabrokenRCSloopin whichcasethattrainisnotassumedtobesuccessfulforhotlegrecirculation.Plantcon"guration(e.g.,impactofdebris,etc.)-Theloadingofdebrisonthesumpstrainershasnoimpactontheactiontoalignforhotlegrecirculation.If theloadingissttocauseanLHSIpumptoloseitsfunction,thenfailure ofallthreesumpsareconservativelyassumedlost,overstatingtheimpactof GSI-191phenomenaintheassessment.Tuesday1 stMarch,2016:19:32,Page123of393 DRAFTPART2.RAIRESPONSES(ROUND1)Whetherthebreakisinthecoldleg-Theproceduralguidanceisnotdepen-dentonthebreaklocationbeinginthecoldorhotlegs.Thesameactionsare taken.TheproceduralcautiontoleaveonetrainofSIalignedtothecoldlegsis alwaysobservednomatterwhattheoperatorsdetermineastothelocationof thebreak.Theextentofcore"owblockagepriortohotlegswitchover-Fortheassess-mentoftheeofGSI-191phenomena,onlyboronprecipitationpriortothe timeofhotlegrecirculationisofinterest.Boronprecipitationafterthetimeof hotlegrecirculationisalreadyconsideredinthebasePRA.Ifthebreakisin thehotleg,boronprecipitationisnotatissue.Ifthebreakisinthecoldleg, andhotlegrecirculationisnotaligned,thenfortheMediumandLargeLOCA breaksizes,boronprecipitationleadingtolossofcorecoolingisalwaysassumed regardlessoftheGSI-191phenomena.

Reference1.SouthTexasProjectHumanReliabilityAnalysisNotebook,STI32746637.2.1.1.18APLAB,STPPRAModel-HumanReliabilityAnalysis:Question6STPResponse:(Item6,Page44)TheoperatoractionsdescribedinSectionC.5.8ofAppendixCtoVolume1areforinadequatereactorcore"owconditions.Theoperatoractionsmodeledin thePRAevaluationofGSI-191phenomenaareinsteadforconditionsinwhich reactorcore"owisadequate.TheGSI-191phenomenaarethenimposedon theseotherwisesuccessfulscenarios.Nocreditisgivenfortheadditionaloperator actionsdiscussedinSectionC.5.8mitigatingthepotentialinadequatereactor core"owconditionsthatmaybecausedbyGSI-191phenomenaasevaluatedin CASAGrande.TheoperatoractionslistedinC.5.8areintendedtodemonstrate thedefenseindepthavailabletodealwithsuchphenomenashouldtheyoccur.TheactionscreditedforMediumandLargebreakLOCAsarepresentedintheeventsequencediagramofAppendixA,FigureA.3.1ofVolume2.The operatoractionsaremodeledintopeventsOR,OS1,OFFS,andHLEG.These arebrie"ydiscussedbelow.TopEventORrepresentstheoperatoractiontomanuallyactuatesafetyinjectionwheneverESFASfailstogenerateasafetyinjectionsignal.Thisaction isrequiredearlyinthescenariofollowingaMediumorLargebreakLOCA

initiator.TopEventOS1representsthemanualactiontosecureonetrainofcontain-mentsprayifallthreeareinitiallyrunning,toconserveRefuelingWaterStorage Tank(RWST)water.Thisactionisunrelatedtothepresenceofdebris.While includedinthePRAeventtreemodel,thestatusofthistopeventisnotconsid-eredinsubsequentevents.Instead,theCASAGrandesimulationaccountsfor thisactionbytheassumedtimesofitsimplementation.TopEventOFFSrepresentsthemanualactiontosecurealltrainsofcontain-mentspraywhenthecontainmentpressurefallsto6.5psigandtheTechnical SupportCenter(TSC)concurs.Thisactionisunrelatedtothepresenceofde-bris.WhileincludedinthePRAeventtreemodel,thestatusofthistopevent isnotconsideredinsubsequentevents.Instead,theCASAGrandesimulationaccountsforthisactionbytheassumedtimesofitsimplementation.ThisactionTuesday1 stMarch,2016:19:32,Page124of393 DRAFTPART2.RAIRESPONSES(ROUND1)isnotexpectedtobeimplementeduntil6.5hoursafteradesignbasisLOCAperOPOP05-EO-EO10.TopEventHLEGrepresentstheactionandequipmentnecessarytoalignatleastonelowheadsafetyinjectiontraintotheassociatedRCShotleg.The operatoractionisnotmodeledasvaryingwiththeamountofdebrisbecauseby procedureitisenteredwhen5.5hourshaveelapsedfollowingthebreak.2.1.1.19APLAB,STPPRAModel-PRAScope:Question1 STPResponse:(Item1,Page44)FragilitycurvesforseismicinitiatedLOCAswerenotdevelopedaspartoftheexistingPRAforSouthTexasProject.SuchLOCAswouldhavetooccur beforetransporttothesumpofdislodgedinsulationwouldbeofconcern.The originalevaluationofseismicfailuresatSTPconcludedthatsuchfailuresofthe RCSwouldhavemedianfailurecapacitiesgreaterthan2.0g;i.e.,seeReference 3.Figure3.6ofReference1presentsgenericfragilitycurvesfortheconditional probabilityofaSmallorMediumsizeLOCAinresponsetoagivenearthquake groundmotion.Morerecently,inReference2,EPRIthencurve"ttheseplots (seeTableH-2ofReference2)toconvertthemtostandardform.Arepresenta-tivefragilitycurveforLargeLOCAsisalsopresentedinReference2.Information fromReference2isprovidedinthetablebelow.LOCASizeMedianAccelerationBeta-rBeta-uHCLPFSmall1.0.3.4.315 Medium.0.35.45.534 Large2.5.3.4.788MostrecentlySTPsubmittedtotheUSNRCitsresponsetotherequestforinformationtoRecommendationTask2.1oftheNear-TermTaskForcein responsetotheFukushimaevent(Reference4).Table2.2.2-1gofReference4 providesanup-to-datemeanfrequencyexceedancecurvefortheseismichazard atSTP.ByconvolutingthishazardcurvewiththeSmall,Medium,andLarge LOCAFragilitiesnotedintheabovetable,thefrequencyofSmall,Medium,and LargeLOCAsinitiatedbyseismiceventsatSTPisfoundtobe4.25X10 7peryearforSmallLOCAs,1.08X10 7peryearforMediumLOCAsand5.06X10 8peryearforLargeLOCAs.Clearlythepotentialforthedislodgementofinsulationbyseismicshakingtobeofconcernisafunctionofthehazardcurveassumed.ForSmallLOCAs, transporttothesumpwouldbeminimalbecausethecontainmentsprayswould notbeinitiated.Forlargerbreaks,whichlikelywouldinitiatecontainmentspray, thefrequencyofsuchseismicallyinitiatedbreaksismuchlower.Becausethein-sulationiscontainedinsidearobustfabriccoveringdesignedforhandling,any insulationthatfailedwouldfallinrelativelylargeclumpswhichwouldbe lesslikelytotransport.Evenassumingnocreditforsumprecirculationfollow-ingaseismicevent,theimpactwouldbeverysmall.Whilenofragilityanalysis hasbeenperformedonpipeinsulationawayfromthebreak,wheresuchin-sulationisassumedtobedislodged,thechancesoftheinsulationfailingand beingtransportedtothesumpmustbesmall.EvenassumingaprobabilityofTuesday1 stMarch,2016:19:32,Page125of393 DRAFTPART2.RAIRESPONSES(ROUND1)0.1thattinsulationisdislodgedandtransportedtothecontainmentsumpstocausesumpplugging,theimpactofrecirculationfailureforMedium andLargeLOCAsinitiatedbyseismiceventswouldthenbeverysmall;i.e.,

0.1(1.08x107+5.06x108)=1.6x108peryear,assuminglatestSTP-speci"cseismichazardmeancurveapplies.

References1.M.P.Bohn,J.A.Lambright,ProceduresfortheExternalEventCoreDam-ageFrequencyAnalysesforNUREG-1150,NUREG/CR-4840,SandiaNational Laboratories,preparedforUSNuclearRegulatoryCommission,November1990.

2.EPRI3002000709,SeismicProbabilisticRiskAssessmentImplementation Guide,FinalReport,December2013,ProjectManagerJ.Sursock.

3.D.A.Wesely,etal.,SeismicFragilitiesofSelectedStructuresandCompo-nentsattheSouthTexasPlant,preparedforPickard,LoweandGarrick,Inc.

byNationalTechnicalSystems,June1987.HL&P1060-DOC-353(c.3),Report No.1628.

4.LetterfromG.T.PowelltoU.S.NRC,SeismicHazardandScreeningReport (CEUSSites),ResponseNRCRequestforInformationPursuantto10CFR50.54(f)

RegardingRecommendation2.1oftheNear-TermTaskForce,ReviewofInsights fromtheFukushimaDai-ichiAccident,NOC-AE-14003114,DatedMarch31, 2014.(ML14099A235)2.1.1.20APLAB,ResultsInterpretation-Quanti"cation:Question 1aSTPResponse:(Item1a,Page45)Thevaluesreportedforandwerecalculatedbyrequantify-ingCDFandLERFassumingtheentireGSI-191phenomenamodelsandthen subtractingthebasecaseCDFandLERFwhichdidnotconsiderGSI-191phe-nomena.Sinceargumentswereprovidedtoshowthatonlythemediumandlarge LOCAinitiatorscouldconceivablycontributeviaconsiderationofGSI-191phe-nomena,therequanti"cationofCDFandLERFwasrestrictedtojustthesetwo initiators.TheandLERFfromotherinitiatorsistoosmalltobeof interest.Thereferencesmentionedtosuccessbranchesandtheexclusionoffailurebranchesreferstothecomputationofthehighestfrequencypumpstatesof interest.Thesepumpstatesweredeterminedforthepurposeofde"ningthe pumpcombinationstatesofmostinteresttoevaluateinCASAGrande.They arenotuseddirectlyincomputingCDFand2.1.1.21APLAB,ResultsInterpretation-Quanti"cation:Question 1bSTPResponse:(Item1b,Page45)ThesameLOCAinitiatingeventfrequenciesandparameteruncertaintydis-tributionswereusedforboththebaselineanddebrismodels.2.1.1.22APLAB,ResultsInterpretation-Quanti"cation:Question 2STPResponse:(Item2,Page45)AppendixAtoVolume2presentstopeventsintheMediumandLargeTuesday1 stMarch,2016:19:32,Page126of393 DRAFTPART2.RAIRESPONSES(ROUND1)LOCAeventtreeset.ThetopeventsrepresentingthesevenfailuremechanismsaredescribedinthelateMediumLOCAeventtree;i.e.,TopEventSUMPcom-binesthefailuremechanismsatthesumpstrainer(i.e.,sumppluggingresulting int"ow,lossofNPSH,pumpcavitationcausedbyairingress,and strainercollapsebyexcessiveloading);TopEventFBLKrepresentsthefailure modesforblockageofthecore(i.e.,excessivepluggingwithinthereactorvessel ofthecoolant"owpathtothecorefueltubes),andTopEventBORONrep-resentsthefailuremodeofexcessiveboronprecipitationttoprevent extendedcorecooling.TopEventFBLKisassignedzeroprobabilityofoccurrenceasaresultoftheCASAGrandeanalysis.Therefore,thesequencesthatresultincoredamage frequencyduetofailureofrecirculationfromGSI-191phenomenaarethose limitedtocaseswheneitherofTopEventsSUMPorBORONfail.Toobtainthetop100sequencesleadingtocoredamagefromonlyGSI-191phenomena,asequencegroupwasde"nedthatrestrictsthesequencesinthe grouptothoseinitiatedbyeitherMediumLOCAorLargeLOCA,whichlead tocoredamageandwhichinvolvefailureofoneofthesplitfractionsfortop eventSUMPorBORON.Thetop100sequencesofthissequencegroupare listedinthefollowingtable.NotethelistofsequencesinVolume2(Table4-7)identi"esexamplesequencesleadingtocoredamageinvolvingMediumand LargeLOCAsandinvolvingGSI-191phenomena.Thattableprovidesadditional insightintothenatureofthescenariosinvolvingGSI-191phenomenathatlead tocoredamage.Foreachsequenceinthegroup,thefollowingispresented:SequenceRankInitiatingEventName InitiatingEventFrequency SplitFractionName SplitFractionFailureProbability TopEvent-SplitFractionDescription EndStateName OverallSequenceFrequency

%ContributiontotheTotalSequenceGroup;i.e.,3.07x10 8peryearNotethatsequencesdependingontheassumedlocationofthebrokenRCSloop,theinitialstatusofmaintenance,thetrainsnormallyrunning,aswell asthespeci"cGSI-191splitfractionwhichisdeterminedbytheECCSpump

state.Thesequencegrouptotalof3.07x10 8peryearisslightlygreaterthantheincreaseincoredamagefrequencyreportedinVolume2,belowTable4-2,as

2.88x108peryear.ThereasonforthisslightincreaseisthatinthemodelincludingGSI-191phenomena,somesequencesarenowassignedtocoredamage becauseofGSI-191phenomenathatwerealreadyassignedtocoredamageinthe basemodelwithoutGSI-191phenomena.Forexample,ifalowfrequencypump stateisoneofthedefaultstates,theassociatedMediumandLargeLOCAs sequencesareassignedtocoredamagebecauseofGSI-191phenomena.Someof thesesequencesarelistedinthetablebelow.AportionofthesesequencesareTuesday1 stMarch,2016:19:32,Page127of393 DRAFTPART2.RAIRESPONSES(ROUND1)alsoassignedtocoredamageinthebasemodelduetolossofbothRHRheatexchangercoolingandcontainmentfancoolercooling.Thesemultiplecausesof coredamageareaccountedforwhensubtractingthetotalstoobtainthechange incoredamagefrequencyduetoGSI-191phenomena.The2.88x10 8peryearvalueisthereforetheappropriatevaluefortheincreaseincoredamagefrequency.Thetop100sequencesleadingtocoredamageduetoGSI-191phenomenaarelistedinthefollowingtable.RankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group1LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA2LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA3LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA4LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.38BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page128of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA5LLOCA5.20E-06Large LOCAMELTSUMP1.04E-093.37BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPD---TMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA6LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA7LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA8LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsB,CRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA9LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.37BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page129of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA10LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA11LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA12LLOCA5.20E-06Large LOCAMELTSUMP1.03E-093.36BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA13LLOCA5.20E-06Large LOCAMELTBORON3.80E-101.24BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEBCA2.67E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint, TrainsC,ARunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES18LLOCA5.20E-06Large LOCAMELTBORON3.79E-101.23BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBBC2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsB,CRunningcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page131of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES22LLOCA5.20E-06Large LOCAMELTBORON3.78E-101.23BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page132of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES23LLOCA5.20E-06Large LOCAMELTBORON3.77E-101.23BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEBAB2.66E-01-GENERICPLANNEDMAINTE-NANCE-NoPlannedMaint,TrainsA,BRunningCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

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CSSTRAINBCSUPPORTAVAIL-

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-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHA PBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:CSSTRAINACSUPPORTAVAIL-

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CSSTRAINABSUPPORTAVAIL-

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-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHAPBZ1.00E+00-SICOMMONTRAINB-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEEDFAILEDCS3AC9.91E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAC:

CSSTRAINACSUPPORTAVAIL-

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-Case3,LH,HH,CS,SICOMSI38AA1.55E-04-SI38PATHA-SI38PATHAPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page135of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDCS2AE9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSAB:

CSSTRAINABSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-ABLERBZ1.00E+00-SIRECIRCULATIONTRAINB-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES33MLOCA3.05E-04Medium LOCAMELTSUMP7.95E-110.26BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case3,LH,HH,CS,SICOMSI38CA1.55E-04-SI38PATHC-SI38PATHC-SI38A=S,SI38B=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEEDFAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:CSSTRAINBCSUPPORTAVAIL-ABLEcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page136of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupRAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES34MLOCA3.05E-04Medium LOCAMELTSUMP7.94E-110.26BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEECA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES36MLOCA3.05E-04Medium LOCAMELTSUMP7.86E-110.26BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case3,LH,HH,CS,SICOMcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page137of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSI38BA1.56E-04-SI38PATHB-SI38PATHB-SI38A=SPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDHBZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLBZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINB-GUARANTEED FAILEDCS4AB9.92E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSBC:CSSTRAINBCSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINACSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES42MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case3,LH,HH,CS,SICOMPAZ1.00E+00-SICOMMONTRAINA-GUAR-ANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page139of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupHAZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINA-GUARANTEED FAILEDLAZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINA-GUARANTEEDFAILEDCS8AB1.30E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:

CSSTRAINBCSUPPORTAVAIL-

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CSSTRAINBCSUPPORTAVAIL-

ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMPSTATES44MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

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CSSTRAINBCSUPPORTAVAIL-ABLERAZ1.00E+00-SIRECIRCULATIONTRAINA-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES45MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES47MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDCS8AE1.30E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:

CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES48MLOCA3.05E-04Medium LOCAMELTSUMP6.69E-110.22BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case3,LH,HH,CS,SICOMPZZ1.00E+00-SICOMMONTRAINC-GUAR-ANTEEDFAILEDHCZ1.00E+00-HIGHHEADSAFETYINJEC-TIONTRAINC-GUARANTEED FAILEDLCZ1.00E+00-LOWHEADSAFETYINJEC-TIONTRAINC-GUARANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page141of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS8AE1.30E-04-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSNO:

CSSTRAINABSUPPORTAVAIL-

ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSUMPZ1.00E+00-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GING-ALLOTHERPUMP STATES49LLOCA5.20E-06Large LOCAMELTSUMP6.13E-110.2BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA50LLOCA5.20E-06Large LOCAMELTSUMP6.13E-110.2BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH,RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA51LLOCA5.20E-06Large LOCAMELTSUMP6.13E-110.2BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH,RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page142of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA52LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH,RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA53LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA54LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA55LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB-Case1,EW,CC,DG,CH,RH, RCFCcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page143of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA56LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH,RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA57LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA58LLOCA5.20E-06Large LOCAMELTSUMP6.12E-110.2BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

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ABLERCZ1.00E+00-SIRECIRCULATIONTRAINC-GUARANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page148of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL226.19E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE22,LARGELOCA72LLOCA5.20E-06Large LOCAMELTSUMP5.38E-110.18BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEEAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA75LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMEFAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA79LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEFCA7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB-MDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA80LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEFBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-MDAFW,SGPORVcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page150of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA81LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMEFAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-MDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA82LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTIMEG7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainD

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CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA83LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMEFAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

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-MDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCAcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page151of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group85LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATIMEG7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainD

-TDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA86LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEFBC7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-MDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA87LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMEFAB7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-MDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA88LLOCA5.20E-06Large LOCAMELTSUMP2.92E-110.1BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTIMEG7.50E-03-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainD

-TDAFW,SGPORVCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONSULL13.40E-03-SUMPSTRAINERDURINGRE-CIRCULATION-SUMPPLUG-GINGSTATE1,LARGELOCA89LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page152of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATERECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES90LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES91LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSD2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPDTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES92LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINScontinuednextpage...Tuesday1 stMarch,2016:19:32,Page153of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES93LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES94LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSC2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPCTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES95LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUEScontinuednextpage...Tuesday1 stMarch,2016:19:32,Page154of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of Group96LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA

-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORTAVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1, HLEG=S,WITHGSI-191ISSUES97LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECCA1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainB

-Case1,EW,CC,DG,CH,RH, RCFCWBZ1.00E+00-ECWTRAINB-GUARANTEEDFAILEDECBZ1.00E+00-ECHTRAINB-GUARANTEEDFAILEDKBZ1.00E+00-CCWTRAINB-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES98LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC

-Case1,EW,CC,DG,CH,RH, RCFC,CVAWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES99LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSA2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPATMECAB1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainC-Case1,EW,CC,DG,CH,RH, RCFC,CVAcontinuednextpage...Tuesday1 stMarch,2016:19:32,Page155of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continuedRankIE/SFValueIETopEvent-SplitFractionDescrip-tionGroupSeqFreq.%of GroupWCZ1.00E+00-ECWTRAINC-GUARANTEEDFAILEDECCZ1.00E+00-ECHTRAINC-GUARANTEEDFAILEDKCZ1.00E+00-CCWTRAINC-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUES100LLOCA5.20E-06Large LOCAMELTBORON2.24E-110.07BRKSB2.50E-01-RCSLOOPBREAKFRACTION-BREAKINLOOPBTMECBC1.53E-02-GENERICPLANNEDMAINTE-NANCE-PlannedMaintTrainA-Case1,EW,CC,DG,CH,RH, RCFC,CVBWAZ1.00E+00-ECWTRAINA-GUARANTEEDFAILEDECAZ1.00E+00-ECHTRAINA-GUARANTEEDFAILEDKAZ1.00E+00-CCWTRAINA-GUARANTEEDFAILEDCS1AA9.87E-01-CONTAINMENTSPRAY-RE-CIRCULATION-State:CSABC:

CSSTRAINABCSUPPORT AVAILABLEOS1Z1.00E+00-OPERATORSSECURE1OF3RUNNINGSPRAYTRAINSOFFSZ1.00E+00-OPERATORSSECUREALLCON-TAINMENTSPRAYFORLATE RECIRCULATIONBLL1S1.25E-03-BORONPRECIPITATIONFOL-LOWINGSUMPRECIRCULA-TION-LLOCA,PUMPSTATE1,HLEG=S,WITHGSI-191ISSUESTotalQuanti"edFrequencyofSequenceGroup=3.0705E-0082.1.1.23APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion2STPResponse:(Item2,Page46)Thechoiceofgeometricmeanvaluesfromtheexpertelicitationwasthemodelthatmostcloselyfollowstherisk-informedmethodologyinwhichparam-etersandmodelsthatrepresentrealisticbehaviorareselected,asopposedto thosethatwouldbeselectedinothersettingssuchasadeterministicframework inwhichthemostpessimisticmodelswouldbeselected.Thetechnicaljusti"ca-tionisprovidedinthewhitepaperincludedasEnclosure2whereitisshown howthearithmeticmeanemphasizesextremevaluesintheLOCAfrequency

setting.Furtherjusti"cationisprovidedinNUREG1829whereitisrecommendedthattheselectionofthefrequencymodelshouldbeappropriatefortheappli-cation(pagexxii)andwhereitisnotedthatalternativeaggregationmethods canleadtosigni"cantlytresults.TheauthorsofNUREG1829goon tosaythataparticularsetofLOCAfrequencyestimatesisnotgenericallyrec-ommendedforallrisk-informedapplicationsandthatthepurposesandcontext oftheapplicationmustbeconsideredwhendeterminingtheappropriatenessof anysetofelicitationresults.BecausethemaximumamountofdebriswouldbeTuesday1 stMarch,2016:19:32,Page156of393 DRAFTPART2.RAIRESPONSES(ROUND1)createdinthelargesthypothesizedLOCAcategories,itisparticularlyappro-priatethattherisk-informedapproachadoptthemodelthatwouldproducethe mostlikelycenterfrequencies(andconcomitantuncertainty).2.1.2ESGBResponses 2.1.2.1ESGB,ChemicalQuestion12 STPResponse:(Item12,Page56)Inthe30-dayCHLEtestsconductedpriortothelicensesubmittal,noalu-minumprecipitationwasobserved,asevidencedbyaluminumconcentrations thatremainedbelowpredictedsolubilitylimitsandnoobservedincreaseintur-biditythatwouldhavebeenindicativeofaprecipitateinsolution.Without directevidenceofaluminumprecipitation,itwasnotpossibletorelatethehead losscharacteristicsofthe30-dayCHLEteststochemicalAsdescribedin theLAREnclosure4-1,page9andinmoredetailinLAREnclosure4-3,Section 5.6.3,safetymarginwasaddedtothechemicalcontributiontoheadloss byapplyingabump-upfactortothecalculatedvalueofconventionalheadloss basedonknownphysicallyrelevantparametersofdebrisbedthicknessandsump "uidtemperature.Thechemicalheadlossbump-upfactordidnotdirectlyuse headlossdatafromtheCHLEtests.Asaresult,variabilitybetweenthethree headlosscolumnshasnobearingontheSTPlicensesubmittal.Althoughpotentialbiasbetweenthethreeheadlossloopshasnoonthelicensesubmittal,STPrecognizesthatitisapilotprojectandthatbiasesin experimentalequipmentmayfuturelicensees.Apossiblebiaswasobserved intwotestseriespriortotheSTPlicensesubmittalwhenthethreecolumnswere linkedtothetank.ThereportsofthesetestserieswereprovidedtotheNRC inSTPLetterNOC-AE-14003075(1).First,inCHLE-008(2),preformed WCAPprecipitateswereintroducedintothetankwhilethetankwasconnected tothecolumns.Onetestwasconductedwithblender-prepareddebrisbedsin allthreecolumnsandasecondtestwasconductedwithNEI-prepareddebris bedsinallthreecolumns.Inbothcases,theheadlossinColumn3increased20 to30minutessoonerthaninColumns1and2.Second,inCHLE-010(3),head lossincreasedondttrendsinthethreecolumnsafterthecolumns(all containingblender-prepareddebrisbeds)werelinkedtothetank,withthehead lossinColumn3dramaticallyhigherthantheothercolumns.This inheadlossoccurreddespitethefactthatnocorrosionmaterials,debris,or precipitationproductswerepresentinthetank.FollowingtheSTPlicensesubmittal,thecontractor,UNM,hasexploredpos-siblecausesforthebiasesobservedinCHLE-008andCHLE-010(2,3).Afactor thatmayhavecontributedtothepotentialbiaswasthepipeheadercon"gu-rationthatsuppliedwaterfromthetanktothethreecolumns.Thecolumns werelocatedonacommonheader,withColumn3beingthelastcolumnonthe header.Thetanksystemwasrecon"guredaftertheSTPlicensesubmittalso thateachcolumnissupplieddirectlyfromthetankwithoutthepresenceofa commonheader.ArepeatofthetestinCHLE-008(2)hasnotyetbeencon-ductedtoascertainwhetheranychangeinperformancehasresultedfromthe pipingmodi"cation.ItshouldbenotedthatothertestswereperformedinwhichnosystematicTuesday1 stMarch,2016:19:32,Page157of393 DRAFTPART2.RAIRESPONSES(ROUND1)biaswasobserved.ThetrendinheadlossintheMBLOCAtest,CHLE-012(4)wassimilarinallthreecolumns,whichcontainedNEI-prepareddebrisbeds.

IntheLBLOCAtest,CHLE-014(5),alsowithNEI-prepareddebrisbeds,the headlossinColumn3wasbetweenthevaluesforColumns1and2.Thebias hasonlybeenobservedwhenblender-prepareddebrisbedswereused.Other testsreportedinCHLE-008(2)demonstratedahighdegreeofinconsistency andinstabilityinblender-prepareddebrisbeds.Theinstabilityoftheblender-prepareddebrisbedscauseslargeincreasesinheadlossfromsmallchangesin particulateconcentration,regardlessofwhetheritisnon-chemicalorchemical precipitate.Theresultsindicatethatthevariabilitybetweencolumnsisampli-

"edsigni"cantlyfortheblender-prepareddebrisbedsandnotevidentforthe NEI-prepareddebrisbeds.Tominimizethisedebrisbedsthataremore prototypicaloftheconditionsduringaLOCAarebeingstudiedatUNM.More prototypicaldebrisbedsaresensitivetothepresenceofprecipitates,butare substantiallymorestablethantheblender-prepareddebrisbed.Moreproto-typicalbedsconsistof"berpreparedwiththeNEIpressure-washingmethod supplementedwitheitherpaintparticlesorlatentdebrisandpaintparticles.

Recenttestshavedemonstratedahighdegreeofstability,reproducibilitybe-tweenreplicatetestsinthesamecolumn,andreproducibilitybetweensimilar bedsintcolumns.Worktocharacterizetheheadlossofthebedsand documentthesuitabilityofthesebedsforfuturechemicalheadlosstestingis currentlyongoing.Informationgainedduringtestingafterthelicenseapplica-tionhasnotchangedtheconclusionsoftheanalysisconductedforthelicense application,andSTPisnotplanninganyadditionalchemicaltestingin supportofthelicenseapplication.

REFERENCES:

1.SouthTexasNuclearOperatingCompany,LettertotheNuclearRegula-toryCommission,NOC-AE-14003075.Feb.27,2014.(ML14072A076)2.UniversityofNewMexico,CHLE-008:DebrisBedPreparationandFor-mationTestResults,Rev.4.Feb.3,2014.(ML14072A082)3.UniversityofNewMexico,CHLE-010:CHLETankTestResultsforBlendedandNEIFiberBedsWithAluminumAddition,Rev.3.Feb.10,2014.(ML14072A083)4.UniversityofNewMexico,CHLE-012:T1MBLOCATestReport,Rev.4.Feb.18,2014.(ML14072A084)5.UniversityofNewMexico,CHLE-014:T2LBLOCATestReport,Rev.3.Feb.22,2014.(ML14072A085)2.1.2.2ESGB,ChemicalQuestion13a STPResponse:(Item13a,Page56)ThealuminummaterialusedintheCHLEtestswasapieceofscaf-foldpickboards(notthepoles)fromtheSTPplant.Theswas typicalsthathadbeeninuseattheplantforseveralyears.Thispiece ofwaschosenbecauseitwastypicalofstoredincontain-ment.Sincontainmentissimilartotheusedconditionofthetested materialbecausesarereusedoverandoveragaininthecontaminated, highradiationareastoavoidspreadingcontaminationandadditionalpersonnel exposurefrommovingtheminandout.Notethatafractionofthesurfacearea ofthetestedmaterial(theedges)wasnotoxidizedbecausethepieceshadtobeTuesday1 stMarch,2016:19:32,Page158of393 DRAFTPART2.RAIRESPONSES(ROUND1)cutinordertoobtainthecorrectareaexposed,whichwouldberepresentativeofdamagetopre-existingscalesurfacesonincontainment.Toprevent anychangetothesurfaceconditionsofthetheonlypreparationin thelabwastocleanthesamplegentlywithmildlaboratorysoaptoremove particulateandallowtodry.2.1.2.3ESGB,ChemicalQuestion13bSTPResponse:(Item13b,Page56)Thecorrosionbehavioroftpartsoftheswasnotcomparedinbenchcorrosiontests.However,othertestingwasperformedthatindicated similarsurfaceconditions,whichwouldbeexpectedtoproducesimilarcorro-sioncharacteristics.Surfaceconditionsweredeterminedusingscanningelectron microscopy(SEM)withenergydispersivespectrometry(EDS)andX-raypho-toelectronspectrometry(XPS).TheSEMimagesinFigure1showthatthe surfaceofportionsoftheusedforsubmergedandvaporspacecondi-tionswerequalitativelysimilaratamicroscopiclevel(1).TheEDSdatashown inTable1alsoshowqualitativesimilaritiesbetweentheportionsofs ing,inthatthesurfaceelementalcompositionisdominatedbyaluminumand oxygen,withsmallamountsofotherelements.TheXPSspectrainFigure2 demonstratesthatbothportionsofshavesurfacelayersconsisting ofaluminumphosphate(AlPO 4)andaluminumoxide/hydroxide[AlOOHor Al(OH)3,whichhaveoverlapping2pspectra].Inbothcases,thesurfacelayersweredeterminedtobeabout90percentAlPO 4and10percentAlOOH/Al(OH) 3(2).Giventhesimilaritiesinsurfaceconditions,incorrosionbehavior arenotexpected.(A)(B)Figure1:Scanningelectronmicroscopeimagesofstobeusedin(A)sub-mergedconditionsand(B)vaporspaceconditions.TheseimageswerecollectedfrompiecesofthatwerenotusedinthecorrosiontestsandrepresenttheconditionasreceivedfromSTP.2.1.2.4ESGB,ChemicalQuestion13cSTPResponse:(Item13c,Page56)ThesurfaceconditionoftheshasnotbeenexposedtoaLOCAjettodetermineiftheoxidewouldspallandresultinagreatercorrosionrate thanobservedduringtheCHLEtesting.Someisstoredintworacks onthecontainment19insidethebioshieldwall(perTechnicalSpeci"cationTuesday1 stMarch,2016:19:32,Page159of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2.1:Elementalcompositionoftobeusedin(A)submergedconditionsand(B)vaporspaceconditions.Thisdatawascollectedfrompiecesofthat werenotusedinthecorrosiontestsandrepresenttheconditionasreceivedfromSTP.ElementPercentmassonscaf-foldingtobeusedin submergedconditionsPercentmassonscaf-foldingtobeusedinva-porspaceconditionsO37.429.1 Na1.30.5 Al49.858.7 Si5.25.1 P3.41.7 Ca0.40.9 S2.5-Cl-0.3 K-1.3 Fe-1.6 Mg-0.6 Zn--(A)(B)Figure2:X-rayphotoelectronAl2pspectraoftobeusedin(A)submergedconditionsand(B)vaporspaceconditions.Thesedatawerecollectedfrompiecesof thatwerenotusedinthecorrosiontestsandrepresenttheconditionas receivedfromSTP.Surveillanceprocedure0PSP03-XC-0002andplantgeneralprocedure0PGP03-ZM-0028),whichisanareawhereitcouldbepartiallyexposedtojettingfrom ahypothesizedfailureproducingajetthatisdirectedtowardthestorageracks.

Thesistightlypackedintoseismically-quali"edstorageracksand, althoughtheracksareopenonthesides,onesideisprotectedbyaconcrete wall,theyareconstructedwithstructuralsteelI-beams,andclosedontheends withstructuralsteeldoorstokeepstoredmaterialfrombeingreleasedduring aseismicevent.Thetightpacking,concretewalls,andstructuralmaterialall serveasbarriersthatlimitexposuretojets.Finally,energeticjetshypothesized toresultfromaLOCAareshortduration(minutes)comparedtocorrosiontimeTuesday1 stMarch,2016:19:32,Page160of393 DRAFTPART2.RAIRESPONSES(ROUND1)scales(hours).Afterthejetdiesdown,thematerialisnolongerexposedtopost-LOCA"uidimpingement.Inaddition,all(100%ofthesurfacearea)ofthe aluminummaterialisconsideredexposedtocontainmentsprayeventhoughitis tightlypackedinthestorageracks.Thisconservativeassumptionisconsideredto outweighanyconsiderationofpotentialincreasedcorrosionofalimitedportion ofthealuminumduetoremovalofanoxidelayerbyimpingement.2.1.2.5ESGB,ChemicalQuestion19 STPResponse:(Item19,Page58)Yes,thetermarti"cialinthecaptionofFigure5.6.6referstotheheadlossin"ationfactordistributionof5

+/-1thatisrandomlysampledandappliedtotheNUREG/CR-6224resultforconventionaldebrisheadloss.2.1.3SRXBResponses 2.1.3.1SRXB,Question1 STPResponse:(Item1d,Page65)TheresponsetoSRXBRAI1wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.2SRXB,Question2 STPResponse:(Item2e,Page65)TheresponsetoSRXBRAI2wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.3SRXB,Question3 STPResponse:(Item3,Page65)TheresponsetoSRXBRAI3wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.4SRXB,Question4 STPResponse:(Item4,Page65)TheresponsetoSRXBRAI4wasprovidedintheSTPlettertoNRCdatedJanuary9,2014NOC-AE-14003057,ML14029A533.2.1.3.5SRXB,Question5a STPResponse:(Item5a,Page65)TheresultsshowninTable2.2.1wereobtainedfromthesimulationsofLOCAscenariosoftbreaksizesperformedwiththeRELAP5-3DandMELCOR inputmodels.Adetaileddescriptionofthesimulationconditionsisreportedin

[1].ThevolumeofthewaterintheRWSTde"nedintheRELAP5-3Dinput modelwasde"nedinaccordancewiththeplantemergencyoperationprocedures 0POP05-EO-EO10step22[2]whichinstructtheoperatortoinitiatethesump switchoverprocedurewhenRWSTlevelislessthan75,000gallons,whichiswhen thelow-lowlevelalarmisactuated.Table1liststheRWSTvolumesofwaterat talarmlevels.TheInjectionwascalculatedasfollow:Max.(Min.)UsableVolume=High-Alarm(LowAlarm)VolumeEmptyVolumeTuesday1 stMarch,2016:19:32,Page161of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2:RWSTVolumesLevelVolume(gal)HighAlarm(Nominal)528,000LowAlarm(Nominal)473,000 Low-LowAlarm(Nominal)75,000 EmptyVolume(Nominal)32,000 MaxUsableVolume496,000 MinUsableVolume441,000 AverageUsableVolume468,500 UsableVolume(LOCA)456,735InjectionVolume(LOCA)413,735AverageUsableVolume=(MaxUsableVolume+MinUsableVolume)/2InjectionVolume=AverageUsableVolume(Low-LowAlarmVolumeEmptyVolume)TheInjectionVolumede"nedintheRELAP5-3Dinputmodelisequalto413,735USgal.2.1.3.6SRXB,Question5bSTPResponse:(Item5b,Page65)Table2showstheECCS"owrateandtheCSS"owrateforthebreaksizesreportedonTable2.2.1.Table3:FlowratesandsumpswitchovertimeBreaksize1.5246815DEGSumpSwitchoverTime5.6h1.3h5.6h55.9m44.2m37.8m29.5mTotalSIFlowRate(gpm)1230.72075.84119.67950.710285.411779.711988.2 TotalCSFlowRate(gpm)0.0 15200.05200.05200.05200.05200.05200.0 1Simulationresultsshowedthatthecontainmentspraysdidnotactuatefora1.5break.Thecontainmentspraysvolumetric"owrateimposedintheMELCORinputmodelwascalculatedunderthefollowingassumptions:

• The"owrateforeachCSpumpwasimposedtobeequalto2600gpm(correspondingtothemaximumsingletrain"owrate)

• Oneofthethreecontainmentspraypumpsmanuallysecuredatthebe-ginningofthetransient[2].2.1.3.7SRXB,Question5cSTPResponse:(Item5c,Page65)Thesumpswitchovertimewascalculatedviaacontrolvariablede"nedintheRELAP5-3Dinput"leasthetimerequiredtodepletetheRWSTinjection volumeof413,735USgal.Detailsofthecontrolvariablelogicadoptedarelisted below:Tuesday1 stMarch,2016:19:32,Page162of393 DRAFTPART2.RAIRESPONSES(ROUND1)1)Acontrolvariablewasde"nedtocalculatethetotalECCS"owrateasthesumofthe"owrateofalltheactivesafetyinjectionpumps(calculatedby theRELAP5-3Dsimulation)andcontainmentspraypumps(calculatedby theMELCORsimulation).2)Anintegralcontrolvariablewasde"nedintheRELAP5-3DinputdecktocalculatethetotalvolumeofwaterwithdrawnfromtheRWST,asthe timeintegralofthetotal"owratedescribedin1).totalinjectedvolume

=t=t t=0 s (total"owrate

)dt3)Thesumpswitchovertimewascalculatedasthetimetatwhichthetotalinjectedvolumecalculatedin2)reachestheRWSTinjectionvolume.2.1.3.8SRXB,Question6STPResponse:(Item6,Page65)Figure1showsthecontainmentpressurevs.timeestimatedusingMELCORfortherangeoftherangeofbreaksizesreportedinTable2.2.1,underthe nominaloperatingconditions[1]:

• NumberofoperatingSItrains=3

• NumberofContainmentSprays=2(onepumpsecuredbymanualproce-dure[2]*Numberoffancoolers=6

• CCWTemperature=85.84FThesprayactuationsetpoint(9.5psig)andthespraysterminationsetpoint(6.5psig)arealsoplottedinthe"gure.2.1.3.9SRXB,Question7aSTPResponse:(Item7a,Page66)TheinstructionsfortransferringtheSafetyInjectionSystemtohotlegre-circulationareprovidedintheEmergencyOperatorProcedure0POP05-EO-ES14TransfertoHotLegRecirculation.Thisprocedureisenteredfromthe 0POP05-EO-EO10LossofReactororSecondaryCoolantStep28,when5.5 hour5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />shaveelapsed.Theactionsfollowedbytheoperatorduringthisprocedurearesummarizedinthetablebelow.2.1.3.10SRXB,Question7bSTPResponse:(Item7b,Page66)ThetableintheresponsetoRAI7aaboveshowstheestimatedtimerequiredtoperformthemanualoperationstocompletethehotlegswitchoverprocedure

[3].Thetimerequiredtocompleteeachoperationdescribedinthetablewere takenfromthegeneraloperatoractiontransittimesandequipmentmanipula-tiontimesfromEOPT-05.01[4]measuredforEmergencyOperatorProcedures localsteptiming.Theseactionsarenottimedinthesimulator.Tuesday1 stMarch,2016:19:32,Page163of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:ContainmentPressureAsspeci"edintheSTPplantemergencyprocedure[3],onlytwoofthethreeSItrainsareswitchedtohotlegrecirculation.Undertheseconditions,thetotal "eldtimerequiredtotransfertheSItrains(two)tohotlegrecirculationis4.5 min.Notethatthisisthelocaloperator"eldtimeandsomeadditionaltimeover the"eldtimeisrequiredtocompletetheotherstepsthatareperformedinthe controlroom.Theadditionaltimerequiredwouldbetomanipulatethecontrol handswitchesandperformthestepexecution(three-waycommunicationand veri"cation,etc.)However,sincetheothermanipulationsareinthecontrolroom onthesamecontrolpanel,15minuteswouldbeadequatetimetocompletethe evolution.2.1.3.11SRXB,Question8 STPResponse:(Item8,Page66)ThevaluesofthetotalSafetyInjection(SI)volumetric"owratesshownintable2.2.14representthevolumetric"owrateatthesumpswitchovertimefor tbreaksizes,calculatedwiththethermal-hydraulicsimulations,assum-ingthatalltheSIpumps(HHSI,LHSI,threeSItrains)areavailableduring thesimulation.AllSIpumpsoperatingisde"nedasthenominaloperatingcon-dition.Foranyothergivenscenario,thevolumetric"owrateforindividualSI pumpswasestimatedbasedontheratioofthemaximumpumpcapacities,using Equations4and5(Volume3,page53of248).NominalSIoperatingconditionsareareasonablesurrogateforallplant-statecon"gurationsbecause:(1)nominalconditionsareexpectedforalmost95%of allLOCAaccidentscenarios,and(2)plantcon"gurationsthatincludefailed SIpumpsdrawwatertothesumpatafarlowerratethanthesmallincrease experiencedfromrelaxationofbackpressureontheRCSbythelossof oneormoreSIpumps.2.1.3.12SRXB,Question9 STPResponse:(Item9,Page66)Tuesday1 stMarch,2016:19:32,Page164of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:Switchovertohotleg:SummaryoftheprocedureSTPResponse:

• TheTotalSIFlowRateisthe"owrateforcedbytheHHSIandLHSIofthethreeSItrains.TotalSIFlowRate=(HHSI"owrate+LHSI"owrate)

• TheTotalECCSFlowRateisthesumoftheTotalSI"owrateandtheContainmentSprays(CS)FlowRate.TotalECCSFlowRate=HHSI"owrate+LHSI"owrate+CS"owrate

• TheTotalSumpFlowRateisthetotal"owthroughthesumpstrainers.Thevalueofthetotalsump"owrateatanytimeisequaltotheTotal ECCSFlowRate:TotalSumpFlowRate=TotalECCSFlowRateTuesday1 stMarch,2016:19:32,Page165of393 DRAFTPART2.RAIRESPONSES(ROUND1)

References:

[1].TexasA&MUniversity,SumpTemperatureSensitivityAnalysisRevi-sion2.0.January2013[2].SouthTexasProjectElectricGenerationStation,LossofReactororSecondaryCoolant.DepartmentProcedureSafetyRelated(Q),0POP05-EO-EO10Rev.20(2011)[3].SouthTexasProjectElectricGenerationStation,TransfertoHotLegRecirculationDepartmentProcedureSafetyRelated(Q),0POP05-EO-ES14 Rev.7(2008).[4].SouthTexasProjectElectricGenerationStation,EOPLocalAction.GeneralOperatorActionTransitTimesEOPT-05.01Rev.5.2.1.4SSIBResponses 2.1.4.1SSIB,ZOI:Question1 STPResponse:(Item1,Page66)TheDEGBvaluescomputedbyEquation22ofLAREncl.4-3(Page125,Section5.3.1)areextraneousinformationandwerenotusedintheanalysis.

Table5.3.1(LAREncl.4-3,Pg.126)includesdatarepresentingthenominal pipesize,actualpipesizeandanunusedextrapolationtoaDEGBsizede"ned byEquation22foreachweldcategory.TheseunusedCADcalculatedDEGB sizeswerealsoapparentinTable5.3.2(LAREncl.4-3,Pg.128).Thepipe scheduleandouterdiameterde"neactualpipesize,synonymoustoitsinner diameterwithinLAREncl.4-3.CASAGrandeanalysisutilizesactualpipesize forallcalculations,includingZOIdetermination.AnactiontoremovetheunusedinformationhasbeenenteredintheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.2.1.4.2SSIB,DebrisCharacteristics:Question2 STPResponse:(Item2,Page66)ThesizedistributionsforNukonandThermalWrapdebriscreatedbythepostulatedLOCAjet(%ofeachsizecategorycreated)areaslistedbelow.These valuesarecontainedinreference46,Table4.1(LAREncl.4-3).NukonandThermalWrapareanalyzedaslowdensity"berglass(LDFG)andhavethesamedebrissizedistributionandZOIs.ThemethodologyNEI04-07Vol.2,reference45,wasusedtodeterminethesizedistributionsandisbasedonair-jetimpingementtests(AJIT).Thedistributionisbasedonthedistanceoftheinsulationfromthebreakandthecorrespondingimpactpressurewitnessedatthetarget.2.1.4.3SSIB,Transport:Question5 STPResponse:(Item5,Page67)Assumption6.h.Vstatesthatallthreestrainersareactiveduringpool"lltransport.Eachsump,regardlessofservicestate,willcollectaquantityof"nes duringpool"llaslistedinTable5.5.3.Tuesday1 stMarch,2016:19:32,Page166of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.4.4SSIB,Transport:Question9STPResponse:(Item9,Page69)Yes,theevaluationincludesthe1.8%as"nedebris.Alleroded"ber(regardlessoforigin)andall"nesandsmall"bersthat havenotsettledaretreatedidenticallyassuspendabledebris.Figure5.5.3of LAREncl.4-3showsthat37.4%ofsmallpiecesgeneratedintheZOIwillbein-troducedtothepoolassuspendedmaterialthateventuallyreachesthestrainer.DebristransportequationsandthedebristransportlogicdiagramsprovidedintheLAREncl.4-3,Section5.5.7describesthetotalamountofsuspendable debristhatisintroducedtothepoolfromeachlowdensity"berglass(LDFG) sizecategory.AllLDFGthatarrivesinthepooliseither(1)treatedassuspended foreventualtransporttothestrainer,(2)sequesteredininactivecavities,(3) applieddirectlytothestrainersduringpool"ll,or(4)settledonthe"oor.ErosionoflargeLDFGpiecescontributestransportabledebristothepool.ErosionofsettledsmallLDFGpiecesinto"nesalsocontributestransportable debristothepool.Onceintroducedtothepool,thesizecategoryoforigindoes nottotaltransportbecausenofurthercreditisappliedforsettling.2.1.4.5SSIB,Transport:Question11a STPResponse:(Item11a,Page69)Thetermx(t)describesthetime-dependentmassofdebrisinthepoolwithanexponentialdecayfunction.Aswritten,thetermx(t)(LAR.Encl.4-3,Equa-tion41,totheJune19,2013applicationML131750250)shouldbedisregarded.ItwastakenoutofLAREncl.4-3(currentlicensingapplication)becauseitwasnotimplementedinCASAGrandeinthisform.CASAGrandetracks eachindividualdebristypewithsolutionstoEquation84(LAREncl.4-3,Pg.

209),whichdescribesthedtialrateofchangeofdebrismasssuspended inthepool.Thedebrisrecirculationtimeisaccuratelyde"nedbytheratioof poolvolume(m3)tototalvolumetric"owrate(m3/s),whichcanchangeasa functionoftimeifpumpsareturnedThex(t)discrepancyhasbeenaddedtotheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.2.1.4.6SSIB,Transport:Question11b STPResponse:(Item11b,Page70)Thetermx(t)wasnotimplementedintoCASAGrandeintheformdiscussedinLAREncl.4-3(June19,2013applicationML131750250,Equation41).The debrisrecirculationtimeisaccuratelyde"nedbytheratioofpoolvolume(m3) tototalvolumetric"owrate(m3/s).Equation84ofLAREncl.4-3(currentapplication,Pg.209)tracksallpar-ticulateand"brousdebristypesthatcanbesuspendedinthepoolassuming ahomogenouslymixedpool.Thisincludesallcoatings(Quali"edandUnqual-i"ed),allotherparticulates,andall"brousinsulationdebristypesinsideofTuesday1 stMarch,2016:19:32,Page167of393 DRAFTPART2.RAIRESPONSES(ROUND1)containmenthavingsizesclassi"edas"nesorsmallpieces.Anerosionfractionisappliedtolargepiecestogenerateadditionalsuspended"ber.Thesizesofall debristypesevaluatedarelistedinTable2.2.21ofLAREncl.4-3(Pg.57).The samedebrisrecirculationtimeappliestoallsuspendeddebris.Equation84ofLAREncl.4-3(currentapplication,Pg.209),onlyappliestothosequantitiesthatarriveonthestrainerduringrecirculation.Thosematerials thatareinitiallytransportedtothestrainer(earlyarrival)asaresultofpool "llandsheeting"owarenotdependentontheratioofpoolvolume(V)to totalrecirculationpump"ow(Q),butrather,areplaceddirectlyontheactive strainersatinitiationoftheLOCA.Theirmasshoweverisaccountedforand trackedinthetotalinventoryduringthescenario.2.1.4.7SSIB,Transport:Question11c STPResponse:(Item11c,Page70)Equation84ofLAREncl.4-3(currentapplication,Pg.209)usedtotrackpooldebrisinventoryassumeshomogeneousmixinginthepoolofsuspended

debris.Thisassumptionisvalidforallsuspendeddebristypesforthefollowing reasons:1.Forallbreaks,theinitialhigh"oorvelocitiesfromsheeting"owcausedbythepipebreakandcontainmentspraysareexpectedtoscatterdebriswith nopreferentialdirectionthroughoutcontainment.2.Finedebriswillbefurthermixedafterrecirculationbecauseofmultidi-rectionalvelocityvectorsandturbulentkineticenergy.Asanaddedconservatism,solutionstothepooltransportequation(LAREncl.4-3,Section5.8,Equation84)donottakecreditforsettlingofdebrisin thepool.ThismeansthatallsuspendeddebrisisrecirculatedthroughtheECCS backintothepooluntil100%iseventuallytrappedatthestrainersoronthe reactorcore.CFDresultsforsteadystate,isothermalrecirculationareshown below.CFDrepresentationsof"owvectorsforanear-sumpandfar-sumplargeLOCAbreaksaredescribedinthe"gures.Inthenear-sumpbreaksimulation (Case1)abreakontheLoopCHotLegwasmodeled,anditwasassumedthat onlytwotrainswereoperable(LAREncl.4-3,Ref.[23],Figure5.8.1Pg.74).

Themulti-directionalvelocityvectorsthroughoutcontainmentduringsteady-staterecirculationareindicativeofhomogenousmixing.2.1.4.8SSIB,Transport:Question11d STPResponse:(Item11d,Page70)Thex(t)functionisnotinLAREncl.4-3andisnotusedinCASAGrande.Theoriginalformulaforx(t)describesthemassofdebrisinthepoolratherthan themassofdebrisonthestrainer,whichexplainsthenon-intuitiveinterpreta-

tion.2.1.4.9SSIB,Transport:Question11e STPResponse:(Item11e,Page70)Thex(t)functionanditsassociateddebrisdepletionrateisnotinLAREncl.4-3andisnotusedinCASAGrande.ThedepletionrateofsuspendedpoolTuesday1 stMarch,2016:19:32,Page168of393 DRAFTPART2.RAIRESPONSES(ROUND1)debrisimplementedinCASAGrandeisbasedon"ber"ltrationandsheddingratesobtainedfromstrainermoduletesting.100%of"berreachingthecoreis permanentlyretained.?2.1.4.10SSIB,Transport:Question13 STPResponse:(Item13,Page70)Microthermisassumedtofailas100%"nesandistreatedassuchintheSTPevaluation.ThediscrepancyinVolume6.2hasbeenenteredintheSTPcorrectiveactionprogramtotrackcorrectionforfuturesubmittals.Inthesecondbreaksimulation(Case2)abreakontheLoopCSIPumpDischargeLinewasmodeledassumingthatonlytwotrainswereoperable(LAREncl.4-3,Ref.

[23],Figure5.8.17Pg.91).Thelocationofthe(Case2)breakisshownbelowinFigure 5.8.17.Themulti-directionalvelocityvectorsthroughoutcontainmentduringsteady-staterecirculationareindicativeofhomogenousmixing.Figure5.8.25showssimilarresultstothoseofFigure5.8.11andcon"rmingthattheTKEafterrecirculationislargeenoughtokeep"ber"neshomoge-neouslymixedthroughoutthecontainmentpool.ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.12Pg.86)for"necoatingschipsareshownin"gure5.8.12.Contoursinyellowshowtur-bulentkineticenergy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page169of393 DRAFTPART2.RAIRESPONSES(ROUND1)ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.20Pg.81)forsmallpiecesof"berglassareshowninFigure5.8.7.Contoursinredshowregionswithtumblingvelocitieslargeenough(0.12ft/s)totumblesunkensmall"berglassdebrisalongthe"oor,whilecontoursinblueareregionswithvelocitiesbelowthistumbling velocity(LAREncl.4-3,Ref.[65]).Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(0.034ft 2/s 2)tokeepsmall"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page170of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.7showsthatforanear-sumpbreak(Case1),thereisnota"owpathtothestrainerthathasTKElargeenoughtosuspendsettlingofsmallpiecesof"berglass.

Thereforetheassumptionthatsmalldebrisishomogenouslymixedinthepoolwithout settlingwhencalculatingthesolutionsofEquation84(LAREncl.4-3,Pg.209)isvalid.

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.20,Pg.94)for smallpiecesof"berglassareshownin"gure5.8.20.Contoursinred,showregionswith tumblingvelocitieslargeenough(0.12ft/s)totumblesunkensmall"berglassdebrisalongthe"oor,whilecontoursinblueareregionswithvelocitiesbelowthistumbling velocity(LAREncl.4-3,Ref.[65]).Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(0.034ft 2/s 2)tokeepsmall"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page171of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.20showsthatforafar-sumpbreak(Case2)thereisno"owpathtothestrainerthathasTKElargeenoughtosuspendsettlingsmallpiecesof"berglass.

ThisisconsistentwiththeresultsofFigure5.8.7,andcon"rmstheassumptionthat smalldebriscanbetreatedashomogeneouslymixedinthepoolwithoutsettlingwhen calculatingthesolutionsofEquation84(LAREncl.4-3,Pg.209).

ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.11Pg.85)for"ber "nesareshownbelowin"gure5.8.11.Contoursinyellowshowturbulentkineticenergy (TKE)largeenough(8.2E-6ft2/s2)tokeep"ne"berglassdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page172of393 DRAFTPART2.RAIRESPONSES(ROUND1)Afterrecirculation(Figure5.8.11)"berandcoatings"nesarelikelytomixmoreevenlythroughoutthepoolduetothewidespreadregionsofTKElargeenoughtosuspend andmixthese"nes(LAREncl.4-3,Ref.[23],Figure5.8.11,Pg.85).

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.25Pg.99)for"ber "nesareshownin"gure5.8.25.Contoursinyellowshowturbulentkineticenergy(TKE) greatenough(8.2E-6ft 2/s 2)tokeep"ne"berglassdebrisinsuspension(LAREncl.43,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page173of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure5.8.25showssimilarresultstothoseofFigure5.8.11andcon"rmingthattheTKEafterrecirculationislargeenoughtokeep"ber"neshomogeneouslymixedthroughout thecontainmentpool.

ResultsoftheCase1analysis(LAREncl.4-3,Ref.[23],Figure5.8.12Pg.86)for"necoatingschipsareshownin"gure5.8.12.Contoursinyellowshowturbulentkineticenergy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page174of393 DRAFTPART2.RAIRESPONSES(ROUND1)Afterrecirculation"nechipswouldbelikelytomixevenlythroughoutthepoolbecauseofthelargeregionsofTKEarelargeenoughtosuspendandmixthese"nes(LAREncl.

43,Ref.[23],Figure5.8.12,Pg.86).

ResultsoftheCase2analysis(LAREncl.4-3,Ref.[23],Figure5.8.26Pg.100)for"necoatingschipsareshownin"gure5.8.26.Contoursinyellowshowturbulentkinetic energy(TKE)largeenough(0.006ft 2/s 2)tokeep"necoatingsdebrissuspended(LAREncl.4-3,Ref.[65]).Tuesday1 stMarch,2016:19:32,Page175of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThedatashowninFigure5.8.26con"rmsthediscussionforFigure5.8.12thatcoating"neswillmixhomogeneouslythroughoutthepoolbecauseoftheirlowTKEsuspension

limit.

TheCFDresultsforthesmalland"nedebrisshowthathomogenousmixingisapplicable forthesedebrissizes.Largedebrissuchasintactblanketsofinsulationandlargepieces werefoundnottotransportunderSTPconditions(LAREncl.4-3,Ref.[23]).Tuesday1 stMarch,2016:19:32,Page176of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.1.4.11SSIB,NPSHandDegasi"cation:Question29STPResponse:(Item29,Page77)WithinCASAGrande,NPSHriscorrectedforthevoidfractionatthepumpinletinaccordancewithRG1.82,Revision4.Additionally,asdescribedinAs-sumption8.i,(LAREncl.4-3)thevoidfractionatthepumpsisconservatively assumedtobethesameasthevoidfractionatthestrainer,i.e.nocreditistaken forbubblecollapse.2.1.5STSBResponses 2.1.5.1STSB:Question1 STPResponse:(Item1,Page81)TheRAIsaredirectedtowardtheapplicationoftheSTPCRMPandSTPsRiskManagedTechnicalSpeci"cations(RMTS).RMTSiscurrentlyuniqueto STP.Asapilotforarisk-informedapproachtoGSI-191debrisissues,STPdid notrelyonRMTSanddoesnotconsiderRMTSimplementationnecessaryfor adoptionoftherisk-informedmethodologyforrespondingtodebrisissuesas theymayTechnicalSpeci"cation(TS)requirements.STPassessesinoperableornonconformingconditionsinaccordancewithproceduresbasedontheguidanceofPart9900oftheNRCInspectionManual.

Thisincludesconditionsthatthesystemswithinthescopeofthislicensing applicationthataresupportedbythesumps;i.e.,ECCSandCSS.STPsex-pectationisthatapplyingRMTStocalculatearisk-informedcompletiontime (RICT)foranemergentdebrisrelatedconditionwillberare.Mostemergent debrisrelatedconditionsareresolvedwithintheoriginalfrontstopcompletion timebypromptremovalofthedebris.Ifadegradedornonconformingconditionrelatedtodebristhefunc-tionoftheemergencysumpsisdiscovered,itwillbeevaluatedinaccordancewith Part9900asnotedabove.TheShiftManageroftheunitwilllikelyre-questapromptoperabilityevaluationbyEngineering.Engineeringwouldmake adeterminationofwhetherthedebriscouldsigni"cantlytheevaluations describedinthisapplicationbyconsiderationofthenature,quantityandloca-tionofthedebris.IfEngineeringdeterminesthedebrisisadequatelyrepresented bytheexistinganalysis,theywillrecommendthatthesumpsareoperable,no TSactionwouldapplyandtheconditionwouldberesolvedinaccordancewith thestationscorrectiveactionprogram.IfEngineeringrecommendsthatthe sump(s)shouldbeconsideredinoperable,andtheconditioncanbequanti"edin theCRMP,thenaRICTmaybecalculated.Therequirementsforapplication ofRMTSareincorporatedintotheindividualTechnicalSpeci"cations(TS)and inanAdministrativeControlProgramTS6.8.3.k,whichinvokesNEI06-09,all ofwhichareimplementedbystationprocedures.Typically,quanti"cationoftheriskwiththedegradedornonconformingcon-ditionwillbeperformedinaccordancewithstationproceduresbyconservatively failingorotherwiseadjustingfunctionsinRICTCal,whichisadatabase ofthousandsofpre-quanti"edPRAplantcon"gurations.Thequanti"cationwill representtheactualplantcon"gurationwiththeinoperablecomponents,includ-inganyotherPRAmodeledcomponentsorfunctionsthatareunavailableatthat time.Thus,fortheexampleofECCS"ow,thequanti"cationwillincludetheTuesday1 stMarch,2016:19:32,Page177of393 DRAFTPART2.RAIRESPONSES(ROUND1)functionsbydebrisplustheunavailabilityofanyothertrainofECCSthatisunavailableatthetime.IfthePRAfunctionalallowanceis applied,thequanti"cationcanforcesomecomponentstobeunavailableforspe-ci"cinitiatingevents,suchaslargebreakLOCAs,whileretainingavailability forotherPRAinitiators.WithregardtochangestoPRAapplications,theSTPRICTCaldatabasewouldbeupdatedtotakeintoaccounttheimpactofthedebrisrelated totheconcernsraisedGSI-191applicabletoequipmentfunctionsinamanner consistentwiththecurrentpracticesde"nedintheSTPCRMPandprogram-maticupdateoftheSTPPRA.Nochangeswouldbenecessaryfortheprocess forprovidingtheassociatedRICTtotheplant2.1.5.2STSB:Question2STPResponse:(Item2,Page81)TheSTPTSBasesdescribetherequirementsgoverningPRAfunctionalityandareexcerptedbelow.Thelastbulletoftheexamplelistisrelevanttodebris relatedconditions.TheresponsetoRAI1,above,alsoaddressestheapplication ofPRAfunctional.TheSTPTSBasesguidanceisconsistentwithSection 2.3ofNEI06-09,Revision0.Thekeyfactorsare:1.TheCRMPallowsapplicationofRMTSforemergentsituationswherealltrainsofafunctionareinoperable,providedthereisPRAfunctionality, butdoesnotallowapplicationofRMTSforacompletelossoffunction.If functioniscompletelylost,thenon-RMTSallowedoutagetimemustbeapplied.

2.ForconditionswherePRAfunctionalitymaybeapplied,theriskfromthe con"gurationmustbequanti"ableusingthePRA.Forsuchcases,PRAinputs wouldbemodi"edtoobtainnewcon"gurationriskvaluesconsistentwithSTP existingproceduresandprocesses.STPTSBasesExcerpt:ApplicationoftheCRMPwillprovideactionforconditionswheremorethanonetrainorchannelofafunctionisinoperable.Inaccor-dancewithNEI06-09,aRICT(Risk-informedCompletionTime) maynotbeappliedforcon"gurationswherethereisacompleteloss offunctionorforpre-plannedactivitieswhenalltrainsofequipment requiredbytheTSLCOwouldbeinoperable.Itispermissibleto applyaRICTforemergentconditionswherealltrainsofequipment requiredbytheLCOareinoperableprovidedoneormoreofthe trainsarefunctionalasdescribedintheguidance.Ifacomponentisdeterminedtobeinoperable,itmaystillbecon-sideredtohavePRAFunctionalityforcalculationofaRICTifthere isreasonableassurancethatitcanperformitsrequiredfunctionsfor eventsnotbythedegradedornon-conformingconditionand iftheconditioncanbequanti"edinthePRA.Iftheseconditionsare notmet,thecomponentwillbeassumedtobenon-functionalfor calculatingtheRICT;i.e.,itwillhavenoPRAFunctionality.ExamplesofwhereacomponenthasPRAFunctionalitysuchthattheconditioncouldbequanti"edinthedeterminationofanallowed outagetimearelistedbelow:Tuesday1 stMarch,2016:19:32,Page178of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• SSCs(Systems,Structures,Components)thatdontmeetseis-micrequirementsbutareotherwisecapableofperformingtheir designfunction.

• SSCsthatareinoperablebutsecuredintheirsafeposition(e.g.,aclosedcontainmentisolationvalve).

• SSCspoweredfromasourceotherthantheirnormalpowersource,providedthealternatepowersourceismodeledinthe

PRA.*AnSSCwithaninoperableautomaticfunctionifthemanualactuationoftheSSCismodeledinthePRA(e.g.,adieselgen-eratorwithaninoperablesequencer).Actuationchannelsare associatedwiththeiractuatedcomponentsortrains.Lossof actuationchannelsisnotconsideredaLossofFunctionunless notrainoftheactuatedSSCfunctionhasPRAFunctionality.

• AnSSCthatisfunctionalformitigationofasetofevents(e.g.steamgeneratortuberupture,smallbreakLOCA)butisnot functionalforothereventsforwhichitiscredited(e.g.large breakLOCAorsteamlinebreak),providingthePRAmodel canquantifytheriskforthecalculationofaRICT.Anexam-pleofthistypeofconditionisdegradationofenvironmental

quali"cation.2.1.5.3STSB:Question3STPResponse:(Item3,Page82)Insulationreplacementinsidecontainmentiseitheralike-for-likereplacementasamaintenanceactivity(rework)orisamodi"cationwithadesignchange thathasbeenapprovedbySTPNOCEngineering.TheSTPNOCdesignchangeprocessproceduresensurethatnewinsulationmaterialthatfromtheinitialdesignisevaluated.TheSTPNOCdesign changeprocessalsocallsforevaluationsofaddedmetalssuchasaluminumthat couldcontributetopost-LOCAchemicalinthesumpwater.Theprocess looksatcoatingsthataretobeusedinsidecontainment.Impactstopost-LOCA recirculation"owpathsandrecirculationsumpdebrisimpactoninternalsof "uidcontainingcomponentsarepartofthedesignchangeevaluationprocess describedintheprocedure.Examplesofwherereevaluationoftheimpactzonewouldbewarrantedin-clude:*Introductionofanewtypeofmaterial

• Increaseofexisting"brousmaterial

• IncreaseofexistingaluminummaterialProceduresandActivitiesintheLicensingBasisinPartIofEnclosure4-1andSection3.3.4ofEnclosure3toReference1ofthecoverletterprovide additionalinformation.Tuesday1 stMarch,2016:19:32,Page179of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2ML14178A481,Secondsetofresponses2.2.1APLABResponses2.2.1.1APLAB,CASAGrande-LOCAFrequencies:Question2 STPResponse(Item2,Page37)TheimplementedcontinuumbreakmodelforSTPNOCyieldsaconditionallikelihoodofadouble-endedguillotinebreak(DEGB)of0.165.Twoalternative modelsareexploredtodeterminetheimpactofthecontinuummodel.The"rst alternativemodelassumesthatallbreaksareDEGBbreaks.Ifthefrequencies fromNUREG-1829arepreserved,this"rstalternativemodelresultsinalower frequencyofbreaksforlargerpipes.Asecondalternativemodelwasexplored inwhichthebottom-upweightingfactorswerenotused.Inotherwords,for thissecondalternativemodel,allpipeswithinasizecategoryhadthesame breakfrequency.Inthissecondalternativemodel,theconditionallikelihoodof aDEGBis0.0746,indicatingthebottom-upportionofthebasemodelused resultsinanincreaseinthefrequencyofaDEGBbyapproximatelyafactorof

2.DetailsaredocumentedinEnclosure1,STP-RIGSI191-RAI-APLA-III-2,Rev.1,RAIAPLA-III-2:ModelingLOCAFrequencyandBreakSizeunder DEGBonlyBreaks,UniversityofTexas2.2.1.2APLAB,STPPRAModel-General:Question2 STPResponse(Item2,Page40)TherisksassociatedwithGSI-191phenomenaareonlyconsideredtobepotentiallysigni"cantforinternalevents.Therefore,whiletheSTPProbabilistic RiskAssessment(PRA)hasnotbeendemonstratedtobefullycompliantwith RG1.200,Revision2,thedbetweenRevision1andRevision2are concernedwithexternalevents.Sinceexternaleventsarenotrequiredinput fortheassessmentofGSI-191phenomena,thisimpliesthattheSTPPRAis tforaddressingtherisksassociatedwithGSI-191phenomena.DeterminationofAdequacyofPlant-Speci"cPRAtoSupportRisk-InformedResolutionofGSI-191,Rev.1includedasEnclosure2supportsthisposition.2.2.1.3APLAB,STPPRAModel-HumanReliabilityAnalysis:Question5STPResponse:(Item5,Page44)TheoperatoractionsonPage37ofVolume3arelistedas:1.SecuringoneContainmentSpraySystem(CSS)pumpifallthreeCSSpumpsaresuccessfullyinitiated2.SecuringallCSSpumpslaterintheevent 3.SwitchovertoEmergencyCoreCoolingSystem(ECCS)sumprecirculationaftertheRefuelingWaterStorageTank(RWST)hasbeendrained4.SwitchovertohotleginjectionTuesday1 stMarch,2016:19:32,Page180of393 DRAFTPART2.RAIRESPONSES(ROUND1)The"rsttwoactionsareincludedintheSTPProbabilisticRiskAssessment(PRA)logicmodelasswitchesbuttheirsuccessorfailurestatusdoesnot thesequenceofeventsmodeled.Theyareincludedinthemodelincaselaterit isdesiredtoperformsensitivitystudies.Theirstatusdoesnottheproba-bilityofsuccessorfailureofactions3and4.Action1isdirectedbyprocedure ReactorTriporSafetyInjection,0POP05-EO-EO00,ConditionalInformation Page.Action2isdirectedbyprocedureLossofReactororSecondaryCoolant, 0POP05-EO-E010,step16C,thisalsorequirescontainmentpressuretobeless than6.5psigandprovidedtheTechnicalSupportCenter(TSC)concurs.Action3,switchovertosumprecirculation,isassumedtoresultincoredam-ageiffailed.Thisisconsistentwiththebasemodelandhasnotbeenchanged inthemodelupdatedtoconsiderGSI-191phenomena.Shortoftdebris tocauselossofsumprecirculation,thepresenceofpartialdebrisinthesump isnotanticipatedtoimpacttheoperatorsperformanceofthisaction.Please alsoseetheresponsetoRAIAPLAB,STPPRAModel-HumanReliability Analysis:RAI6inSTPlettertoNRCdatedMay22,2014,NOC-AE-14003103, (ML14149A434).Action4,switchovertohotleginjection,followsaction3inthesequence,toalignforECCSsumprecirculationtothecoldlegs.Precedingaction3is alwayssuccessfulwhenaction4isqueriedsinceaction4isonlyofinterestif coredamagehasnotalreadyoccurred.Therefore,nodependenceisassumed betweenactions3and4.Thestatusofaction3isalwaysassumedsuccessfulinCASAGrande,beforeconsideringtheGSI-191phenomenasinceitsfailurealreadyguaranteescore damageformediumandlargeLossofCoolantAccidents(LOCAs).Sinceac-tions1and2donotimpacttheSTPPRAlogicmodel,thereisnoneedto interfacetheexacttimingoftheactionsinCASAGrandewiththeresponsein theSTPPRA.Action4,switchovertohotleginjection,occursafterthetimes ofgreatestinterestinCASAGrande,inparticularthoseinvolvingfailuresof sumprecirculation.Fuel"owblockagefailureisboundedbythefailurecriteria forboronprecipitation.BoronprecipitationrelatedtoGSI-191phenomenaends atthetimeofswitchovertohotleginjection.Oncehotleginjectionissuccessful thiseliminatesthepotentialforexcessiveboronprecipitationafterthattime.If switchovertohotleginjectionfails,thestatusofboronprecipitationafterthat timeisnotofinterestbecauseboronprecipitationisassumedforthefraction ofbreaksinthecoldleg.Consequently,informationaboutswitchovertohotleg injectionassumedinCASAGrandealsoneednotbetransferredtotheSTP PRAlogicmodelforevaluation.

Reference:

1.Letter,G.T.Powell,STPNOC,toNRCDocumentControlDesk,FirstSetofResponsestoApril,2014,RequestsforAdditionalInformationRegarding STPRisk-InformedGSI-191LicensingApplicationRevised,May22,2014, NOC-AE-14003103(ML14149A434)2.2.2ESGBResponses 2.2.2.1ESGB,ChemicalQuestion3 STPResponse:(Item3,Page54)Tuesday1 stMarch,2016:19:32,Page181of393 DRAFTPART2.RAIRESPONSES(ROUND1)TheexponentialProbabilityDensityFunction(PDF)isashifted,truncated,andsingle-parameterfunctionthatrequiresonlythemeanvaluetospecify theentirecontinuousdistributionforallx>1,wherexisthechemicalhead-lossfactor.Themaximumchemicalfactorsforsmall,mediumandlarge breaks-15.3forsmallbreakLOCA(SBLOCA),18.2formediumbreakLOCA (MBLOCA),and24forlargebreakLOCA(LBLOCA)werecalculatedasper-centilesoftheirrespectivedistributionsthatpreserveatailprobabilityof1E-05.

Thismeansthatonly1in100,000randomsamplesfromthedistributionwould begreaterthanthereportedmaximum.Themaximawereincludedinevery Latinhypercubesample(LHS)replicate,andtheywereassignedaweightof 1E-05torepresentallchemicalfactorsthatmightbehigher.Assignmentofamaximumchemicalfactorat1E-05isonlyarbitraryinthesensethatthischoicecontrolstheprobabilityweightcarriedbyanyfailures inducedbychemicalfactorssampledfromthehigherrangeofthedistribution.

Theweightof1E-05waschosentocorrespondtopercentilesthatensureaquan-ti"ablenumberofchemicallyinducedEmergencyCoreCoolingSystem(ECCS) failures.Ifnoinducedfailureswereobserved,thenthemaximawouldindeed besuspect,andthetailprobabilitywouldneedfurtherreduction.Withcon-ventionaldebrisheadlossintherangeofafewfeetandastructurallimitof only9.35ft.,chemicalfactorsexceeding10leadtofailure.Therefore,these-lectedmaximawouldbeconsideredconservativefortheLossofCoolantAcci-dent(LOCA)spectra.Beyondthestatedmaxima,probabilityweightsbecome vanishinglysmall,andsamplingbeyondthestatedmaximawouldnotinduce anyadditionalfailures.2.2.2.2ESGB,ChemicalQuestion7 STPResponse:(Item7,Page55)ChemicalHeadLossExperiment(CHLE)TankTests1and2(theMBLOCAandLBLOCAtests)didnotresultintheformationofchemicalprecipitates.

Basedonthealuminumconcentrationsmeasuredinsolution,thoseresultswere consistentwiththeexistingequilibrium-basedmodelforthepredictionofthe thresholdconcentrationsofspeciesthatcouldresultinprecipitation.Experi-mentsconductedbyArgonneNationalLaboratory(ANL)wereidenti"edthat supporttheequilibrium-basedmodel.Figure1isareprintfromAluminum SolubilityinBoronContainingSolutionsasaFunctionofpHandTemperature (ADAMSAccession#ML091610696)(1).This"gureshowstheresultsofalarge numberofbench-topandverticalloopexperimentsandotherliteraturedataat variouspHandtemperaturevalues,withseparationofthedataintoaregion whereprecipitationoccurredandaregionwhereprecipitationdidnotoccur.The authorspresentedequationsforempiricallinesseparatingthetworegionswith theexceptionofafewoutliers,andasecondsetofequationsforlines(shifted upward)thatencompassallinstancesofprecipitation.TheauthorsofRef.1subsequentlypublishedthedatainNuclearEngineeringandDesign(2).Thesecondpublicationincludedanadditionallineonthegraph showingthepredictionofthesolubilityofamorphousaluminumhydroxidebased onanequilibrium-basedmodel(VisualMINTEQ).Figure2isareprintofthe "gureanddemonstratesexcellentagreementbetweenANLsempiricalboundary linesandthepredictionsofVisualMINTEQ.UsingthesameapproachastheTuesday1 stMarch,2016:19:32,Page182of393 DRAFTPART2.RAIRESPONSES(ROUND1)original"gure,anupwardshiftoftheVisualMINTEQlinewouldencompassallinstancesofprecipitation.TheupwardshiftoftheVisualMINTEQlineneces-sarytoencompasstheprecipitationdataisa0.45-unitincreaseinpH+p[AI]

T;inaddition,thisupwardshiftencompassesallprecipitationdatathroughoutthe entiretemperaturerangewithasingleequation,whereastheempiricalbound-ariesinRef.1includedaseparateequationforthedataabove72C(175F).Figure1:(ReprintedfromRef.1):AlstabilitymapinthepH+p[AI]

Tvs.temperaturedomainforsolutionscontainingboron.Filledandopensymbolsmeantheoccurrenceof Alhydroxideprecipitationandnoprecipitation,respectively.pH+p[AI]

TmeansthesolutionpHattemperatureandthenegativelogtothebase10ofthetotalaluminum contentasdissolvedorprecipitateinunitsofmol/kg.CHLETankTests3and4weredeveloped(asareplacementforthetestsde-scribedintheoriginaltestplan)tocon"rmthevalidityoftheliteraturedataand theexistingVisualMINTEQmodelforamorphousaluminumhydroxidesolubil-itywiththeplant-speci"cchemistryatSTP.Figure3presentstheresultsofall 5CHLEtanktestsinthesameformatastheANLdata.Thedatademonstrate thatCHLETankTests1,2,and5occurredinthenon-precipitationregion,and thattheprecipitationthatresultedfromexcessivequantitiesofaluminumin CHLETankTests3and4wereconsistentwiththeexistingdataandmodel.An upwardshiftof0.45unitsofpH+p[AI]

TencompassestheprecipitationdataofTests3and4;thisupwardshiftissimilartothatnecessarytoencompassthe precipitationregionintheANLdata.SinceCHLETankTests3and4adequatelycon"rmedthethresholdconcen-trationsatwhichprecipitationwouldoccurbasedonexistingmodelsanddata, noadditionaltestsareplanned.TheconsistencybetweentheresultsofCHLETuesday1 stMarch,2016:19:32,Page183of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:(ReprintedfromRef.2):AlhydroxideprecipitationmapinthepH+p[AI]

Tvs.temperaturedomainbasedonANLsbenchtopandlooptestdataandliterature data.TankTestsandexistingdataandmodelprovidesjusti"cationfortheengineer-ingjudgmentapproachusedforaluminumsolubilityinthelicensesubmittal.

However,theengineeringjudgmentwasbasedonadirectapplicationoftheVi-sualMINTEQamorphousaluminumhydroxidesolubilitypredictionwithoutthe shiftof0.45units,sincethelicensesubmittaloccurredbeforeCHLETankTests 3and4hadbeenconducted.Theshiftof0.45unitsresultsinasmallreduction oftheconcentrationatwhichaluminumprecipitatesintherangeofpH7.0to 7.3at60C(140F).

References:

1.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,andNatesan,K.AluminumSolubilityinBoronContainingSolutionsandaFunctionofpHandTemperature.ADAMS AccessionNo.ML091610696,ArgonneNationalLaboratory,September,2008.2.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,Natesan,K,andKlein,P.Eval-uationofprecipitatesusedinstrainerheadlosstesting:PartIll.Long-term aluminumhydroxideprecipitationtestsinboratedwater.NuclearEngineering andDesign,vol.241,no.5,pp.1914-1925,2011.Tuesday1 stMarch,2016:19:32,Page184of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure3:AlhydroxideprecipitationmapoftheCHLETankTestsinthepH+p[AI]

Tvs.temperaturedomain.Opensymbols(gray)indicateresultswhereprecipitationwas notobservedandclosedsymbols(black)indicatewhereprecipitationwasobserved.Eachtestisrepresentedbyanapproximatelyhorizontalseriesofdatapoints(near-constantvaluesofpH+p[AI]

Tasthetemperaturedeclinedoverthedurationofthetest).Tuesday1 stMarch,2016:19:32,Page185of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.2.3ESGB,ChemicalQuestion11aSTPResponse:(Item11a,Page56)Itispossibleforfallingwaterfromapipebreakorotherlocationstoimpingeonthegratingsorothergalvanizedsurfaceswithinthecontainmentbuilding.

Directjetimpingementfromabreakcouldcausedamagetogalvanizedsurfaces butwouldbeforarelativelyshortdurationandoveralimitedarea.Continued impingementfromtheContainmentSpraySystem(CSS)couldoccurforseveral additionalhoursuntilthesystemissecured.Ifgalvanizedsurfacesarelocated belowthebreak,fallingwatercouldimpingeonthesurfacesevenafterthesystem issecured,althoughthesurfaceareaimpingedinthismannerwouldbelimited inextent.ChemicalHeadLossExperiment(CHLE)tankteststhatcontainedgalva-nizedsteelorzincsurfacesexperiencedaninitialpeakinturbidityandzinc concentrations,asdescribedintheCHLE-020document(1).Testingconducted foranotherlicenseeaftertheSTPlicensesubmittaldemonstratedthatthezinc releasewasassociatedwiththeinitialperiodoflowpHwhenTri-sodiumPhos-phate(TSP)wasnotpresent(2)WhenTSPwaspresentandthepH wascircumneutral,theinitialreleaseofzincdidnotoccur.Thus,itisexpected basedonthecurrentdatathattheperiodoftimethatzincwouldbereleased fromgalvanizedsurfaceswouldbelimitedtotheinitialportionoftheaccident sequencebeforetheTSPhasfullydissolvedintothecontainmentsolution.

References1.UNM,CHLE-020:TestResultsfora10-daychemicaltestsimulating LBLOCAconditions(T5),Rev.3.UniversityofNewMexico,Albuquerque,NM.

Feb.22,2014,ML14072A079.2.UNM,CHLE-SNC-006:BenchTestResultsforSeries2000TestsforVogtleElectricGeneratingPlant,Rev.1.UniversityofNewMexico,Albuquerque,NM.

Nov.292013.2.2.2.4ESGB,ChemicalQuestion11b STPResponse:(Item11b,Page56)Zincfromgalvanizedsurfacesmightbeconsideredtocontributetoheadlossintwoways.First,zincproductsdislodgedfromgalvanizedsurfacesduringtheinitialphasesoftheLossofCoolantAccident(LOCA)(beforetheTSPdis-solves),asobservedinsomeoftheChemicalHeadLossExperiment(CHLE) tanktests,maycontributeanadditionalparticulatesourceduringtheinitial developmentofthedebrisbed.Thiscontributionwasconsideredtobesmall (lessthan10percent,basedonconcentrationsmeasuredinsolution)compared toothersourcesoflatentdebrisinthecontainmentbuildingandwasnotex-plicitlyconsideredasaseparatesourceofparticulate.Thesecondsourceofzinc fromgalvanizedsurfacesistheslowformationofzincphosphateonthegalva-nizedsurfaceduetoreactionsbetweenthezincinthegalvanizedcoatingand thephosphateinthesolution.VisualobservationsofthecouponsintheCHLE tanktestsindicatedthatthisproductformedslowlyoveraperiodofmanydays andremainedlargelyadheredtothecoupons.Whilequantitativeratesofzinc phosphateformationwerenotobtainedfromtheCHLEtanktests,qualitative observationsindicatedthattheproductwouldnotbepresentuntillaterintheTuesday1 stMarch,2016:19:32,Page186of393 DRAFTPART2.RAIRESPONSES(ROUND1)accidentsequencewhentemperatureswerelowerandstrainer"owrateswerelower,allowingadditionalmarginforheadlossthroughthestrainer.Analysis indicatedthattheproductwascrystalline,whichwouldbeexpectedtocon-tributetolessheadlossthanamorphouscorrosionproducts.Basedonthelate formationofthismaterial,itsadherencetosurfaces,andcrystallinenature,this materialwasconsideredlesssigni"cantintheSTPchemicalanalysisand itsformationwasnotexplicitlyconsideredintheanalysisdescribedinVolume 6.2.Thebump-upfactorusedtoapplychemicalheadlosswasnotcal-culatedonthebasisofindividualchemicalproducts,andthepotentialforzinc phosphatetobeacontributortochemicalheadlosswasimplicitlyconsidered duringthedevelopmentofthebump-upfactors.2.2.2.5ESGB,ChemicalQuestion17 STPResponse:(Item17,Page57)Everysimulatedbreakhasitsowntime-dependentconventionalheadlossthatiscalculatedbasedondebrisaccumulationand"owrate,andaddedto abaselineclean-strainerheadlossof0.22feetofwater.Chemicalfactorsare appliedtotheconventionalheadlosswhenthetemperatureislessthan140

+/-5Fandthe"berloadexceeds1/16in.equivalentthickness.Totalheadlossiscomparedateverytimesteptotheperformancemetricsof(1)NPSHavail,(2)voidfraction,and(3)mechanicalbuckling.Foreverybreakwithaconventionalheadlossintherangeof1ft.ofwaterandamechanicalloadinglimitofonly9.35ft.,achemicalhead-lossfactorexceeding 10willinducefailures.Achemicalhead-lossfactorof43wouldleadtobuckling failureofthestrainerforallsimulatedbreaksinCase01,fulltrainoperation.A chemicalhead-lossfactorof209wouldleadtotheviolationoftheNPSHmargin criterionandfailureforallsimulatedbreaksinCase01,fulltrainoperation.ThesesolutionswereobtainedbyextractingthenecessarydatafromtheCASAGrandeCase01simulation.Anexampleforthelarge-breakpopulation ofchemicalfactorsneededtoinducemechanicalbucklingfailureisshownin FigureA.Thecumulativedistributionfunction(CDF)illustratesthepercentage ofLBLOCAcasesthatwouldfailforchemicalfactorsx.FigureA:CDFforminimumchemicalfactorrequiredtoexceedstrainerbucklinglimitforlargebreaks.Tuesday1 stMarch,2016:19:32,Page187of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.2.6ESGB,ChemicalQuestion20STPResponse:(Item20,Page59)PrototypicalSTP-speci"cstrainerheadlosstestswereconductedatAldenResearchLaboratory(ARL)inFebruary (1,2)andJuly,2008 (3,4).TheFebruaryheadlosstestsweresupersededbytheJulyheadlosstests,becausetheFebruary testsusedwalnut"ourasaparticulatesurrogate.Thereducedamountre"ects mostcloselytheamountofdebrisfromthemajorityofthelargebreaks.The CASAGrandeheadlosspopulationforCase01(allequipmentstartsandruns) wascomparedtoalloftheprototypicalstrainerheadlosstestsconductedat ARL.ThemaximumconventionalCASAGrandeheadlosswas8.2ft,which boundsthemaximumtestedheadlossesforalloftheARLtests,exceptTest3 inFebruary.Test3wasterminatedafterlargeheadlosses,greaterthan15ft, wereobservedfollowingtheadditionof"ne"brousdebris (2);asstatedabove,thistestusedwalnut"ourasaparticulatesurrogateandwassuperseded.The maximumpredictedchemicalCASAGrandeheadlosswas154.9ft,which boundsalltheARLtests.ThemaximumpredictedtotalCASAGrandehead losswas161.9ft,whichboundsalltheARLtests.Also,expectedvaluesofexponentialdistributionsappliedforchemicalhead-lossfactorswerechosentobeconsistentwithstrainertestdatashowingchemical inducedhead-lossincreasesofapproximatelyafactorof2.VogtleElectricGeneratingPlant(Vogtle)conductedprototypicalstrainerheadlosstestsattheAlionhydraulicslaboratory (5).Figure1displaysthepro-totypicalVogtleandSTPstrainermodules.BothmodulesarePCISure-Flow Rdesigns.AlltheSTPstrainertestswereconductedatanapproachvelocityof0.0086 ft/s (2,4);theVogtlestrainertestswereconductedatanapproachvelocityof0.0150ft/s (5).DebrisweightsperprototypicalstrainerareaforgeneraldebristypesaredisplayedinTable1.However,thespeci"cinsulationproductstested undereachdebris-typecategorybetweenthetwoplants.Forexample,STP testedNUKON RandThermalWrapunderthelow-density"berglass(LDFG)category,whereasVogtleonlytestedNUKON RundertheLDFGcategory.Figure1:Vogtle(left)andSTP(right)PrototypicalStrainersUtilizedforTesting.Themaximumconventional,chemicalandtotalheadlossespredictedbyCASAGrandeforCase01alsoboundVogtlesprototypicalstrainerheadloss testing,whichmeasured5.5ft,6.3ft,and11.8ft,respectively (5).Tuesday1 stMarch,2016:19:32,Page188of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table1:DebrisComparisonbetweenSTPandVogtle (2,4,5)UtilityTestLDFGFinesper Strainer Area, lbm/ft2LDFGSmallsper Strainer Area, lbm/ft 2Particulateper Strainer Area, lbm/ft 2CalciumPhos-phate,lbm/ft 2Aluminum Oxyhydroxide, lbm/ft 2SodiumAluminum Silicate, lbm/ft 2STPFeb.Test40.220.31.160.10.430 STPFeb.Test50.140.191.160.10.430STPJulyTest20.060.110.640.10.450VogtleAllTests0.310.146.60.0900.14Fortheheadlosscomparisonscitedabove,theSTPtestsatARLandVogtletestsatAlionwerenotcorrectedtoacommon"owrateandtemperature,which isconservative.Thetemperaturerangeforthesetestswas51Fto117F (1-5)andthetemperaturerangeforCASAGrandeis117Fto255F(LAREnclosure4-3,Table2.2.13)correctingtheteststoahighertemperaturewouldreducethe headloss.TheARLtestsmodeledthemaximumSTP"owcondition.Case 01ofCASAGrandewassimulatedatthemaximumSTP"owcondition,but containmentspraypumpsweresecuredduringtheLOCA.Therefore,theCASA Grandeheadlosspopulationmayinherentlyincludeheadlossesat"owrates lowerthantheARLtestcondition.TheVogtletestswereconductedatahigher "owratethantheSTPtests.Therefore,correctingtheVogtleteststoalower "owratewouldreducetheheadloss.Allfactorsconsidered,thebenchmark comparisonsofmaximalcomputedheadlossmeetorexceedallapplicabletest dataforSTPandVogtle.

References

1.0415-0100067WN/0415-0200067WN.SouthTexasProjectTestPlanFeb 2008.RevisionA.11/24/2008.

2.0415-0100069WN/0415-0200069WN.SouthTexasProjectTestReportfor ECCSStrainerPerformanceTestingFeb2008.RevisionA.11/24/2008.

3.0415-0100070WN/0415-0200070WN.SouthTexasProjectTestPlan.Re-visionA.8/14/2008.

4.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportfor ECCSStrainerTestingJuly2008.RevisionA.11/24/2008.

5.ALION-CAL-SNC-7410-005.HeadLossTestingofaPrototypicalVogtle1 and2StrainerAssembly.Revision0.12/31/2009.2.2.2.7ESGB,ChemicalQuestion22a STPResponse:(Item22a,Page59)ThetestsdescribedinCHLE-010,CHLETankTestResultsforBlendedandNEIFiberBedswithAluminumAddition 1didnotcontainaluminumoxy-hydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.

IntheCHLE-010testseries,aluminumoxyhydroxideprecipitatewasgenerated byinjectinganaluminumnitratesolutiondirectlyintothetankrecirculation line.Thealuminumnitratesolutionwasinjectedinperiodicbatchesataslow ratecorrespondingtoanincreaseinaluminumconcentrationinthetankof0.02 mg/Lperminute.Precipitationoccurredwhenthealuminumnitratecamein contactwiththesolutioninthetank,whichcontainedplant-speci"cconcen-trationsofboricacid,lithiumhydroxide,andtri-sodiumphosphate(TSP)andTuesday1 stMarch,2016:19:32,Page189of393 DRAFTPART2.RAIRESPONSES(ROUND1)washeatedtoabout45degreesFatthetimeofaluminumnitrateinjection.Incontrast,theWCAP-16530-NP-Aprotocolinvolvesamorerapidadditionof solidaluminumnitrateandsodiumhydroxideintonormalpotablewaterina mixingtankatambienttemperaturewithatargetaluminumoxyhydroxidecon-centrationbetween2,100and11,000mg/L.TheCHLE-010testsweredesigned tosimulatetheslowreleaseofaluminumduringcorrosionandtheconditionsfor precipitateformationweresubstantiallydtfromtheWCAP-16530-NP-A protocol.Earliertests,describedinCHLE-008,DebrisBedPreparationandForma-tionTestResults 2andprovidedtotheNRCSinSTPLetterNOC-AE-14003075,datedFebruary27,2014(ML14072A076),didincludealuminumoxy-hydroxideprecipitategeneratedaccordingtotheWCAP-16530-NP-Aprotocol.

Inthosetests,additionoftheWCAPprecipitatestocolumnswiththesame typeofdebrisbedastheMBLOCAandLBLOCAtests(theNEI-prepared debrisbed)didresultinsubstantialheadloss.InCHLE-008Test5,thead-ditionofWCAPprecipitatestoanNEI-prepareddebrisbedatanapproach velocityof0.093ft/scausedsucharapidincreaseofheadlossthatthestain-lesssteelsupportscreencollapsedbeforetheentirebatchofprecipitateswas added.InCHLE-008Tests6and8,additionofWCAPprecipitatetothecol-umnresultedinsubstantialheadlossthroughtheNEI-prepareddebrisbedat anapproachvelocityof0.01ft/s,whichiscomparabletothatoftheSTPstrain-ers.Thequantityofaluminumoxyhydroxideprecipitatethatcausedsigni"cant headlosscorrespondedtoascreenloadingof246g/m2.Forcomparison,the strainertestingdoneforSTPatAldenResearchLaboratorybyAREVA 3 hada"nalaluminumoxyhyroxideprecipitatescreenloadingof2,200g/m2.Test13 inCHLE-008involvedtheadditionofWCAPprecipitatestotheCHLEtank andexcessiveheadlosswasdetectedinallthreecolumns.TheCHLE-008test resultsdemonstratethatthedebrisbedsusedintheMBLOCAandLBLOCA testswerecapableofdetectingaluminumoxyhydroxideprecipitatesgenerated accordingtotheWCAP-16530-NP-Aprotocolviaaheadlossmeasurement.ThediscussionbetweentheNRCandSTPduringtheSeptember2012phonecallfocusedontherelativedegreeofsensitivitybetweentheNEI-prepareddebris bedsandtheblender-prepareddebrisbeds.TheCHLE-008andCHLE-010test resultsdemonstratedthatthethresholdloadingrateforthedetectionofhead lossinblender-prepareddebrisbedswaslowerthanintheNEI-prepareddebris beds.Unfortunately,theblender-prepareddebrisbedsexperiencedsigni"cant headlosswhenchemicalprecipitateswerenotpresentandexhibitedotherforms ofinstabilitysuchasanon-linearresponseto"uidvelocityorquantityof"ber, makingthemunsuitablefordetectionofchemicalprecipitatesintheCHLEtests.

Inaddition,acomparisonoftheloadingratesatwhichheadloss"rstoccurred intheNEI-prepareddebrisbedsintheverticalcolumnandthemixed-debrisbed intheAREVAstrainertestingindicatesthatthethresholdfordetectinghead lossisnotaslowintheNEI-prepareddebrisbedasitisinthemixed-debrisbed.

Thus,neithertheNEI-preparednortheblender-prepareddebrisbedsprovideda tmethodofdetectingchemicalprecipitatesviaaheadlossmeasurement.ItisalsoimportanttonotethattheMBLOCAandLBLOCAtestsemployedmultipleparameterstodetectthepresenceofprecipitatesinadditiontohead lossthroughthedebrisbeds.SampleswereperiodicallyanalyzedfortotalandTuesday1 stMarch,2016:19:32,Page190of393 DRAFTPART2.RAIRESPONSES(ROUND1)dissolvedaluminumperiodicallyduringbothtests.Nosigni"cantbe-tweentotalanddissolvedaluminumwasdetected,indicatingthatallaluminum wasinadissolvedform.Themeasuredtotalconcentrationswerebelowthesat-urationconcentrationpredictedforamorphousaluminumhydroxidebyVisual MINTEQ,corroboratingtheevidencefromthetotalanddissolvedmeasure-ments.TurbidityremainedlowthroughouttheMBLOCAandLBLOCAtests.

ResultsreportedinCHLE-010demonstratedalinearresponsebetweenthead-ditionofaluminumandtheturbidityofthesolution,indicatingthatturbidity iscapableofdetectingprecipitatesthatforminthisexperimentalsystem.Thus, evenintheabsenceofthecolumnheadlossdata,theresultsfromtheMBLOCA andLBLOCAtestscanbeusedtodemonstratethataluminumchemicalpre-cipitatesdonotforminthesimulatedMBLOCAandLBLOCAenvironments.Toaccountfortheuncertaintyassociatedwiththeheadlosscharacteristicsofvariousdebrisbedsandthevariouswaysofgeneratingchemicalprecipitates, safetymarginwasaddedtothechemicalcontributiontoheadlossby applyingabump-upfactortothecalculatedvalueofconventionalheadlossas describedintheLAREnclosure4-1,page9andinmoredetailinLAREnclosure 4-3,Section5.6.3.Thechemicalheadlossbump-upfactordidnotdirectlyuse headlossdatafromtheCHLEtests.Asaresult,theabilityofthetestscreen debrisbedtodetectchemicalprecipitateshasshownnottoin"uencetheresults describedintheSTPlicensesubmittal.

References

1.UniversityofNewMexico,CHLE-010:CHLETankTestResultsforBlendedandNEIFiberBedsWithAluminumAddition,Rev.3.Feb.10,2014.(ML14072A083)2.UniversityofNewMexico,CHLE-008:DebrisBedPreparationandFor-mationTestResults,Rev.4.Feb.3,2014.(ML14072A082)3.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting,Doc.66-9088089-000.2.2.2.8ESGB,ChemicalQuestion22b STPResponse:(Item22b,Page59)TheobjectiveoftheCHLEtestingprogramwastogenerateexperimentaldatatosupportanoverallrisk-informedapproachtotheresolutionofGSI-191,whilealsoconductingamanageablenumberoftests.Eachtestwithinthe programhadmultipleobjectives,withtheintentthatthetestingprogramas awholeprovideddatatosupporttheresolution.Inclusionofallmaterialsin alltestswouldnotnecessarilyhaveprovidedthemostcomprehensivedata, sinceinsomecasesthepresenceofonematerialmightreducethecontribu-tionofchemicalfromanothermaterial.InthecaseoftheMBLOCA andLBLOCAtests,theinclusionofzincintheLBLOCAtestandnotinthe MBLOCAtest,coupledwithcomparisonsofpredictedreleaseratesfromthe WCAPequations,demonstratedthatthereleaseofaluminumwasgreaterwhen zincwasnotpresent.Thatimportantoutcomewouldnothavebeenrecognized ifzinchadbeenincludedinalltests.WhilethetestsincludeddtmaterialsandaspectsoftheLOCAtosat-isfydtobjectives,theconditionswithineachtestwererepresentativeofthe plant-speci"cenvironmentfortheincludedmaterials.Manyfactors,including thequantitiesofboricacid,tri-sodiumphosphate(TSP),andlithiumhydroxide;Tuesday1 stMarch,2016:19:32,Page191of393 DRAFTPART2.RAIRESPONSES(ROUND1)thetimingofTSPdissolution,acidgeneration,andsprayduration;thetemper-aturepro"le;andapproachvelocitythroughthescreenswereallrepresentative oftheplant-speci"cenvironment.FortheMBLOCAtest,thequantitiesofalu-minumand"berglasswerealsorepresentativeoftheplant-speci"cenvironment duringaMBLOCA.2.2.3SCVBResponses 2.2.3.1SCVB,Question:1a STPResponse:(Item1a,Page61)Section1ofEnclosure2-3ofthelicenseamendmentrequest(LAR)identi"estheContainmentSpraySystem(CSS)astheonlysystemforwhichtheproposed exemptiontoGDC-38wouldapply.TheCSSistheonlysystemcreditedfor meetingGDC-38thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftherisk-assessmentprovidedintheSTPlicensing

application.2.2.3.2SCVB,Question:1b STPResponse:(Item1b,Page61)ThesecondparagraphofGDC-38prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-38utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailure in10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethat couldresultinthefailureofmultiplecomponents.Therisk-informedassessment demonstratesthechangeincoredamageorlargeearlyreleasefrequencyfrom thedebrisisverylowinaccordancewiththeguidanceofRG1.1742.2.3.3SCVB,Question:2a STPResponse:(Item2a,Page61)Section1ofEnclosure2-4ofthelicenseamendmentrequest(LAR)identi"estheContainmentSpraySystem(CSS)astheonlysystemforwhichtheproposed exemptiontoGDC-41wouldapply.TheCSSistheonlysystemcreditedfor meetingGDC-41thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftherisk-assessmentprovidedintheSTPlicensing

application.2.2.3.4SCVB,Question:2b STPResponse:(Item2b,Page61)ThesecondparagraphofGDC-41prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-41utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailureTuesday1 stMarch,2016:19:32,Page192of393 DRAFTPART2.RAIRESPONSES(ROUND1)in10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethatcouldresultinthefailureofmultiplecomponents.Therisk-informedassessment demonstratesthechangeincoredamageorlargeearlyreleasefrequencyfrom thedebrisisverylowinaccordancewiththeguidanceofRG1.174.2.2.3.5SCVB,Question:3a STPResponse:(Item3a,Page62)ThelicensingbasisfortheassessmentoftheeofdebrisisbeingrevisedandthedescriptionoftheriskassessmentwillbedescribedintheSTPUFSAR asdiscussedinthelicenseamendmentrequest,Enclosure3,Attachment2.The resultsoftherisk-informedassessmentdemonstratethatthecontainmentsumps aretlyreliableinsupportoftheContainmentSpraySystem(CSS)such thatthefunctionoftheCSSwithrespecttocontainmentanalysisremainsas currentlydescribedintheUFSAR.2.2.3.6SCVB,Question:3b STPResponse:(Item3b,Page62)BackgroundandReferencetoSubmittalDocumentation Theproposedmethodologyisnotconservativewithrespecttoinputsandas-sumptions.Theproposedmethodologyisnotproposedtoreplacetheconservatively-basedmethodologydescribedintheUFSAR.Moredetailsareprovidedinthe followingparagraphsandtables.AsdescribedintheLAR,theproposedexemptionsfromGeneralDesignCri-teria(GDC)-35,theEmergencyCoreCooling,GDC-38,ContainmentHeat Removal,andGDC-41,ContainmentAtmosphereCleanupareforapproval ofarisk-informedapproachforaddressingGSI-191andrespondingtoGeneric Letter(GL)2004-02forSTPUnits1and2asthepilotplantsforotherlicensees pursuingasimilarapproach.Asfurtherdescribed,STPNOCseeksNRCapproval basedonadeterminationthattherisk-informedapproachandtheriskassoci-atedwiththepostulatedfailuremechanismsduetoGSI-191concernsmeetsthe guidance,keyprinciplesforrisk-informeddecision-making,andtheacceptance guidelinesinRG1.174.STPisnotproposingtoapplytherisk-informedapproachtorevisetheli-censingbasisforcontainmentdesigndescribedintheUFSAR.Theproposedrisk assessmentevaluatesaspectrumofLossofCoolantAccident(LOCA)scenarios toquantifytheamountofdebrisofvarioustypesthatmightbegeneratedand transportedtotheemergencysumps,andhowthatdebrismightavailable NPSHforEmergencyCoreCoolingSystem(ECCS)andContainmentSpray System(CSS)pumpstakingsuctionfromthesumpsintherecirculationmode.

Italsoevaluatespotentialtransportofdebristothereactorcore.Itcalculates failureprobabilitiesthatarefedtotheSTPPRA.BecausetheLARisbasedonarisk-informedanalysis,thenatureoftheen-gineeringsupportinseveralareasfordecision-makingisfundamentallyt fromthemethodsusedintheexistingdeterministically-basedLicensingBasis (LB)analyses.Thecontainmentanalysisisanexampleofsuchanareaofd ence.Therisk-informedapproachtoresolvingGSI-191appliestheProbabilistic RiskAssessment(PRA)modeltoquantifytheriskassociatedwithGSI-191 concernsbycalculatingtheinriskfortwocases:Tuesday1 stMarch,2016:19:32,Page193of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• Theactualplantcon"gurationforSTPUnits1and2,withfailuresduetoGSI-191concerns,and

• Thesameplantcon"gurationforSTPUnits1and2,exceptfortheas-sumptionthattherearenofailuresduetoGSI-191concerns.Enclosure1totheLARprovidesthegenericmethodologyfortheproposedrisk-informedapproachtoresolvingGSI-191,consistentwithRG1.174guid-ance.ThisenclosuredescribestherequiredinputstothePRAmodel,thebasic structureforappropriatelymodelingtheinputs,andperformancecriteriaused tocalculatetherisk.AsdescribedinEnclosure1,therisk-informedapproachto resolvingGSI-191usestheplant-speci"cPRAwithrealisticmodelingtoquan-tifytheresidualriskassociatedwithGSI-191andtoevaluateforacceptable sumpdesigninsupportofsuccessfulECCSandCSSoperationinrecirculation modefollowingpostulatedLOCAswiththedebrisdiscussedinGSI-191.TheCurrentLBModelingApproachThelicensingbasis(LB)containmentanalysisisbasedontheCONTEMPTcomputercodeandisdocumentedinSTPcalculationNC07032.TheCON-TEMPTcodeisdocumentedintwoseparatedocuments,NUREG/CR3716and NUREG/CR4001.ThecurrentLBcontainmentanalysisuses260degreesFforthesump"uidtemperatureanddoesnotcontemplatestrainerfailureduetotheconcernsraised inGSI-191.Theanalysisisdesignedtomaximizecontainmentpressure(andtem-perature),whichwouldactuallyimprovenetpositivesuctionheadavailable.The conditionassumedintheLBanalysisisveryunlikelytoberealizedinoperation.

BecausetheLBCONTEMPTmethodologyisnotintendedtore"ectrealistic containmentresponsebehavior,andisbasedonanextremelyunlikelyscenario, theLBmodelingapproachdfromtheapproachusedforcompliancewith RG1.174requirements.Inparticular,CONTEMPT4hasbeenveri"edtoperformtwomajoranalyses[4,PageLOCAU-11]:

• containmentpeakpressureandtemperatureanalysis,and

• containmentenvironmentalthermodynamicconditionsforequipmentqual-i"cationandisolatedpipepressurizationpurposes.TheRiskInformedModelingApproachThecontainmentanalysisisbasedontheSTPMELCORmodelthatrunssimultaneouslywiththeSTPRELAP5modeldesignedforuseintheSTPPRA fortheevaluationrequiredintherisk-informedapproachforaddressingtheGSI-191issue.AsdescribedinLAREnclosure5,Item5.a.13:In-VesselFiberLimits, severalparametersrelatedtogeometry,thermalhydraulics/heattransfer,and engineeredsafetyfeaturesusedintheMELCORinputweretakenfromaprevi-ouslycerti"edModularAccidentAnalysisProgram(MAAP)STPcontainment model.Hence,thecerti"cationdocumentfortheMAAPmodelisappropriately referencedthroughoutthetext.Thefollowingtableliststhemajorqualitativedbymodelingsub-jectareabetweentheriskassessmentandLBcontainmentmodels.Inthenext section,numericalvaluesarecompared.Tuesday1 stMarch,2016:19:32,Page194of393 DRAFTPART2.RAIRESPONSES(ROUND1)SubjectRELAP/MELCORCONTEMPTSubcompartment analysisYesNoCONTEMPThas1largevolume(1pool,1atmosphere)andisnotvalidatedforsubcompartmentanal-ysis.MELCORhasseveralsub-compartments.ModelinggoalsContainmentpressureresponseSumpPooltemperaturere-sponsePeakPressureanalysis(struc-turaldesigntesting,leakrate testing)andcontainmentther-modynamicconditionsFundamentallytmodelinggoalsdrovethemodelingdecisions foreachcodeandexplainsomeof theinassumptionsfor eachmodel.ModelvariationsSinglecontainmentmodelre-gardlessofprimarysidecharac-teristics,breaksize,orstageof thetransient(e.g.before/after sumprecirculation)2separatemodels:oneforeachtransientstage(injection,re-circulation).Also,tas-sumptionsfortsteam generatortypes,primaryside characteristics,modelinggoals, etc.ThesingleMELCORmodelworksinconcertwithRELAP5-3Dforalltransientstages.Primarysidechar-acteristicsaretheexclusivedomain ofRELAP5-3Dduringacoupled run.TheCONTEMPTmodelmay assumeseveraltformsde-pendingontransientstage,primarysidecharacteristics,etc.Modelingphiloso-phyBest-estimateConservativeESFdelays,freevolumecalcula-tions,othermodelcharacteristics arebest-estimatefortheMELCOR modelbutaregenerallyconserva-tivefortheCONTEMPTmodelCodeexecutionOnce-through,coupledrunfromstartofthetransientto conclusionCanbeaniterativeprocessconsistingofinitialruns,sensi-tivityruns,con"rmatoryruns, etc.ThereisnoneedforacollectionorsuccessionofrunsforMEL-COR/RELAP.Undercertaincir-cumstanceswithCONTEMPT,the usermustperformseveralruns toascertainset-points,switchover times,etc.CodeelementsControlvolumes,"owpaths,heatstructures,engineeredsafetyfeatures,controllogicControlvolumes,heatsinks,engineeredsafetyfeatures,con-trollogicCONTEMPThasno"owpathssinceitisasingle-volumemodel.Bothmodelshavecontrolvolumes, heatsinks/structures,andengi-neeredsafetyfeatures.Detailsof thecodeelements EngineeredSafetyFeaturesFancoolers,spraysFancoolers,spraysBothcodesmodelfancoolersandsprayswithsomecorrela-tionorphysicsmodel(notidenti-calones).Actuationset-pointsare basedonsetsofassump-tions.Again,best-estimatescenar-iosareusedforMELCORand conservativescenariosareusedfor

CONTEMPT.ContainmentheatremovalNeglectheatlossthroughcon-tainmentwalls,noCSSorRHR heatexchangermodeling(han-dledinRELAP5-3D)Includeheatlosstoenviron-ment,accountforCSS/RHR heatexchangersandpumpsin

CONTEMPTBecauseCONTEMPTisnotcoupledinrealproblemtimeto anothercodethatmodelsthe RHRheatexchangers,CSSheat exchangers,anddetailsofLH-SI/HHSI,theseelementsmustbe modeled.RELAP5-3DhandlestheseaspectsofthecalculationintheMELCOR/RELAP5-3D coupledrun.Heatsinks/con-densationMELCORbuilt-incorrelationsforbothatmosphereandpool heattransfercotcalcu-lations.Concretecontainmentwallsaremodeledwithoutthesteelliner.Uchidaand/orTagamicorrela-tionsused.Steellinersincluded oncontainmentwallswithair gapbetweenlinerandconcrete.Constantheattransfercocientwithpool.Condensationheattransferistreatedtlyandheatsinks havetcharacteristics.

Liquidpoolheattransferiscal-culatedinternallybyMELCORbutassumedintheCONTEMPTmodel.Sumppooltreat-mentNodecayheatadded.Massandenergysubtractedfromthe poolbasedonRELAP5-3Din-

structionsOnly1largepoolforwholecontainment,perhapsnotin-tendedtocapturethetruebe-haviorofthesumppool.Decay energyaddeddirectlytopoolinrecirculationphase.Thelarge,lumpedpoolofCON-TEMPTvs.thesmaller,annular sub-compartmentpoolofMELCORPipebreak mass/energy

sourceCommunicatedfromRELAP5-3Dviacouplinginterfaceas problemtimeprogresses.The sourceissplitbyMELCOR intopartliquidwater,part steam,andpart"fog"TakenfromRELAPorRE-TRAN,butnotcommunicated inrealproblemtime.All mass/energyaddedexclusively totheatmosphereduringblow-downAllmass/energytoatmosphereinCONTEMPTvs.splitbetweenat-mosphere/poolinMELCORSummaryComparisonofMainParameterValuesThemainnumericalinputparameterscontrollingtheinitialconditionsandboundaryconditionsfortimingandactuation,etc.,betweenRELAP5/MELCOR andCONTEMPTaresummarizedinthefollowingtable.Tuesday1 stMarch,2016:19:32,Page195of393 DRAFTPART2.RAIRESPONSES(ROUND1)CONTEMPTValueRELAP5-3D/MELCORValue Initial Condi-tionsSinglecompartmentfreevolume3.3E+6ft3Sumoverallcompart-ments3329332.0ft3Initialcontainmenttemperature114FInitialatmospheretemperature119.93FInitialcontainment pressure14.5psia(maxT)or15.1psia(maxP)Initialcontainment pressure14.94psiaInitialrelativehumid-ity20%Initialrelativehumid-ity,partialpressureof watervapor70%/1.184psiaInitialRWSTtemper-ature130FInitialRWSTtemper-ature85F EngineeredSafety FeaturesSpraysetpoint(HI-3)12.0psigSpraypressureset-point9.5psigSprayactuationtimesDependsontimeofHI-3trips:0-15.5s,delay=82.6s15.5-29s,delay=

96.1s29-40.5s,delay=

107.6s40.5-52.0s,delay

=119.1s>52.0s,delay=(HI-3time)+69.1sSprayactuationtimes15sdelayaftersetpoint,linearramptofull"owFancoolersetpoint (HI-1)5.5psigFancoolerpressuresetpoint3.0psigFancooleractuation times38sdelayafterHI-1signal tripsFancooleractuation times15sdelayaftersetpoint MaterialProper-tiesThermalconductivityConcrete-0.8BTU/hr*ft*FStainless Steel-9.4BTU/hr*ft*FThermalconductivityConcrete-0.54BTU/ft*hr*FStainlessSteel-f(T),variesSpeci"cheatcapacityConcrete-0.208BTU/lbm*FStainless Steel-0.111BTU/lbm*FSpeci"cheatcapacityConcrete-0.20BTU/lbm*FStainlessSteel-f(T),variesDensityConcrete-144lbm/ft3StainlessSteel-488lb-

m/ft3DensityConcrete-144lbm/ft3Stain-lessSteel-495lbm/ft3 References

1.STPCalculationNC07032,ContainmentLOCAPressure/TemperatureAnalysis,STI33686837.2.NUREG/CR3716,CONTEMPT4/MOD4AMulticompartmentCon-tainmentSystemAnalysisProgram3.NUREG/CR4001,AnImprovementtoCONTEMPT/MOD4Multicom-partmentContainmentSystemAnalysisProgramforIceContainmentAnalysis4.STPGuideLOCAP/TANALYSISUSERGUIDE,Revision4,STI31870431 5.TAMU-GSI-002,MELCORInputDeckCerti"cation:SouthTexasProjectLargeDryContainment,STI336470842.2.3.7SCVB,Question:3c STPResponse:(Item3c,Page62)STPproposestosupplementtheexistingUFSARdescriptionwithade-scriptionoftheriskassessmentofdebrisdescribedinAttachment2to Enclosure3ofReference1tothecoverletter.2.2.3.8SCVB,Question:4a STPResponse:(Item4a,Page62)ThelicensingbasisfortheassessmentoftheeofdebrisisbeingrevisedandthedescriptionoftheriskassessmentwillbedescribedintheSTPUFSAR asdiscussedinthelicenseamendmentrequest,Enclosure3,Attachment2.The resultsoftherisk-informedassessmentdemonstratethatthecontainmentsumps aretlyreliableinsupportoftheContainmentSpraySystem(CSS)such thatthefunctionoftheCSSremainsascurrentlydescribedintheUFSARwith respecttodoseassessment.Tuesday1 stMarch,2016:19:32,Page196of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.3.9SCVB,Question:4bSTPResponse:(Item4b,Page63)Thecurrentlicensingbasiscontainmentatmospherecleanupmethoddoesnotspeci"callyaddresstheofdebrisontheContainmentSpraySystem (CSS).FromthestandpointofGDC-41andCSS,theparameterofinterestis availableNPSHintherecirculationmode.Otherthantheevaluationofthe debrisonCSS,theriskassessmentdoesnotevaluatecontainmentatmo-spherecleanup.Theriskassessmentshowsthattheprobabilityofdebris availableNPSHforCSSsuchthattheCSSwillnotperformitsfunctionisvery smallinaccordancewiththeRG1.174acceptancecriteria.2.2.3.10SCVB,Question:4c STPResponse:(Item4c,Page63)STPproposestosupplementtheexistingUFSARdescriptionwiththeriskassessmentofdebrisdescribedinthelicenseamendmentrequest,Enclo-sure3,Attachment2.2.2.3.11SCVB,Question:5 STPResponse:(Item5,Page63)AsdiscussedintheresponsetoSCVBRAI3.b,above,STPisnotproposingtoapplytheRG1.74risk-informedapproachtorevisethelicensingbasisfor containmentdesigndescribedintheUFSAR.Thecontainmentpressuresand temperaturescalculatedintherisk-informedanalysisdependonthespeci"c casesevaluatedandaretime-dependent;however,thevaluesthatcorrespond tothecurrentUFSARdesignbasisconditionsarecomparabletothecurrent designandlicensingbasisresults.Theresultsoftheanalysisshowthatthe probabilitythatdebriswillpreventtheEmergencyCoreCoolingSystem(ECCS) andContainmentSpraySystem(CSS)fromperformingtheirrequiredfunction isverysmallinaccordancewiththecriteriaofRG1.174andthosesystemsare consideredabletoperformtheirfunctionsasdescribedintheUFSAR.Thereis nochangeintheirdesignbasiswithrespecttocontainmentdesign.2.2.3.12SCVB,Question:6 STPResponse:(Item6,Page63)SeetheresponsetoSCVB-RAI5,above.2.2.3.13SCVB,Question:7 STPResponse:(Item7,Page63)TheriskassessmentislimitedtoevaluatingtheofdebrisonEmergencyCoreCoolingSystem(ECCS)andContainmentSpraySystem(CSS)inthe recirculationmode.Asdiscussedintheresponsesabove,itisnotproposedto replacethecurrentdesignbasiscontainmentanalyses.Itisnotproposedasa changetotheECCSevaluationmodelandSTPdoesnotproposetoapplyit toshowthat10CFR50.46(b)(1)limitsaremetforpeakcladdingtemperature.

Theresultsoftheanalysisshowthattheprobabilitythatdebriswillpreventthe ECCSfromperformingitsrequiredfunctionisverysmallinaccordancewiththe criteriaofRG1.174andthesystemisconsideredabletoperformitsfunctionTuesday1 stMarch,2016:19:32,Page197of393 DRAFTPART2.RAIRESPONSES(ROUND1)asdescribedintheUFSAR.ThereisnochangeintheECCSdesignbasiswithrespecttocontainmentpressure.2.2.3.14SCVB,Question:8 STPResponse:(Item8,Page63)Earlyindevelopmentoftherisk-informedapproachforGSI-191investiga-tion,extremecoreblockagescenariosinvestigationsforcoreandReactorCoolant System(RCS)responsewereunavailableintheacademicliterature.STPthere-foreundertookbasicresearchtounderstandsuchcoreandRCSresponsesin theoreticallyextremescenarios.Themainideabehindthesesimulationswas toinvestigateandunderstand,assumingthat"owblockagecouldoccur,which extremetheoreticalscenarioswouldgotosuccessandwhichwouldleadtofail-ure.Resultsofthestudiesperformedhavesincebeenpublishedinpeer-reviewed

literature.Scenariosweredevelopedassuminginstantaneousblockageatthetimeofrecirculationswitchoverforhotandcoldlegbreaklocationsandsize(small, medium,andlarge)toaccountfort"owpatternsandRCSresponseas describedintheLAR.Thebreaksizeswerechosenathighvaluesforsmall, medium,andlargeSTPLOCAcategories.Allthecasesassumedthatoneofthe EmergencyCoreCoolingSystem(ECCS)trainsisinthebrokenleg(STPLoop B)therebyminimizingeeinjection"owtothecore.Thismatrixresultsin sixscenarios.TheprimaryobjectivewastostudythecoreandRCSresponseforthemainbreaklocationsandsizestogainunderstandingoftheseverityofsuchresponses underextremeconditionsofblockage.Because"owfromthesumpwouldtake a"niteamountoftimetocarryanydebristothecore,itisclearthatsuch instantaneousblockÂagecouldonlyberealizedintheory.Blockage,shouldit actuallyoccur,wouldrequiresomeamountoftimetobuildup.Thescenarios selectedthereforerepÂresentoutcomesfortheoreticalextremes.Theresultsare usefulforsuccesscriteriaintheProbabilisticRiskAssessment(PRA)andfor safetymarginaskedforinRG1.174.Thatis,byinvestigatingtheseextreme theoreticalscenarios,wecouldseethatthevastmajorityofhypothesizedLOCA scenarioswouldgotosuccess.STPinvestigatedadditionalmarginalcasesas furtherdescribedintheLAREnclosure5(Volume6.2,page117,Item5.a.14),

whereeithertherewas"owthroughthebbypassregion(with-outcreditforLOCAholesintheorthroughasmallopening(onefuel channel,eitherperipheralorcenter)inthecore.2.2.3.15SCVB,Question:9a STPResponse:(Item9a,Page63)Thelicenseamendmentrequest,Enclosure2-2,Section1identi"estheEmer-gencyCoreCoolingSystem(ECCS)astheonlysystemforwhichtheproposed exÂemptiontoGDC35wouldapply.TheECCSistheonlysystemcredited formeetingGDC-35thattakessuctionfromthecontainmentsumpsduringthe recirculationmodeofaccidentmitigationandisconsequentlysubjecttodebris whicharethefocusoftheriskassessmentprovidedintheSTPlicensing

application.Tuesday1 stMarch,2016:19:32,Page198of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.3.16SCVB,Question:9bSTPResponse:(Item9b,Page63)ThesecondparagraphofGDC-35prescribesthedeterministicapproachtotheanalysisthatassurescompliancewiththecriterion.Theproposedexemption toGDC-35utilizestheapplicationofarisk-informedapproachperRegulatory Guide1.174fortheassessmentoftheeofdebris.Debriscould allthreeemergencysumpsandconsequentlyallthreetrainsoftheContain-mentSpraySystem(CSS).Inaccordancewiththede"nitionofsinglefailurein 10CFR50,AppendixA,thiswouldbeconsideredasingleoccurrencethatcould resultinthefailureofmultiplecomponents.Theriskassessmentdemonstrates thechangeincoredamageorlargeearlyreleasefrequencyfromthedebris isverylowinaccordancewiththeguidanceofRG1.174.2.2.4SNPBResponses 2.2.4.1SNPB,Question:1a STPResponse:(Item1a,Page64)Thevolumeofthelowerplenumis638.7ft 3.Thevolumeofthecoreis715.1ft 3.Thevolumeoftheupperplenumbelowthebottomelevationofthehotlegis 520.51ft 3.Diagramsdisplayingthesevolumesandtheirrespectiveelevationsareshown below.

Reference:

1.T.Crook,A.Franklin,J.Scherr,R.Vaghetto,A.Vanni,andY.Hassan, SouthTexasProjectPowerPlantRETRAN-RELAP5-3DConversionTables, July2013.Tuesday1 stMarch,2016:19:32,Page199of393 DRAFTPART2.RAIRESPONSES(ROUND1)Tuesday1 stMarch,2016:19:32,Page200of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.2SNPB,Question:1bSTPResponse:(Item1b,Page64)NuclearSteamSupplySystem(NSSS)parametersareprovidedhereforsteadystatefullpoweroperationundernominalconditions.Toexaminethe pressurelossesateachsectionoftheloop,individualpressuresweretakenfrom theRELAP5-3Dsteady-statesimulation(1).Figure1showstheRELAP5-3D nodalizationoftheplantfromRef.1.forreferenceinthefollowingtables.Figure1:RELAP5-3DNodalizationDiagramofthePrimarySystem(AccumulatornotShown)Table1:Steady-StatePlantOperatingConditionsParameterSteadyStateConditions(units)LoopMassFlowRate10108.453(lbÂm/s)UpperPlenumBypassFraction2.080(%)

CoreFlowRate36998.386(lbm/s)Core/VesselInletTemperature560.977FAverageCoreOutletTemperature626.354FReducedFlowAreaDuetoSGtubePlugging0%(NoSGplugging)Table3showsthe"owareas,hydraulicdiameters,andk-losscotsattlocationsoftheprimarysystem,identi"edasjunctionsbetweennodes incolumnRELAP5-3DJunctionID.ThelockedrotorReactorCoolantPump(RCP)k-factor,calculatedwiththeRELAP5-3Dsteady-stateinputmodelisshownbelow:K rotor=5.86

Reference:

1.STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.July2013.Tuesday1 stMarch,2016:19:32,Page201of393 DRAFTPART2.RAIRESPONSES(ROUND1)Table2:RELAP5-3DLoopPressuretialsLocationRELAP5-3DNodesIDRELAP5-3DPressureChange(psid)PumpInlet11202-1130150.3095PumpOutlet11301-1160126.0005 VesselInlet11601-501010.6746 Downcomer53501-501014.2771UpperPlenumBypass58501-50101-41.9059Core84501-54501-37.4984 VesselOutlet10001-84501-17.648 HotLeg10402-10001-0.4353 SGPlenumInlet10601-104025.4342 SGU-tubesInlet10801-10601-5.3809 SGU-Tubes10808-10801-15.4235 SGU-TubesOutlet11001-108081.4743 SGPlenumOutlet11202-11001-9.3558 VesselInlettoExit50101-8650138.8255Table3:RELAP5-3DLoopFlowAreasandFrictionalk-lossFactorsLocationRELAP5-3DJunctionIDFlowArea(ft2)JunctionHydraulicDiameter(ft)Forward k-lossReverse k-lossUpperPlenum-HotLegjX21(865-X00)4.58692.416670.11940HotLeg-SGPlenumInletjX05(X04-X06)4.58692.585830.464640.279639SGPlenumInlet-U-tubesjX07(X06-X08)15.29290.05066670.230.491709U-tubes-SGPlenumOutletjX09(X08-X10)15.29290.05066670.4917090.23SGPlenumOut-let-Crossover LegjX11(X10-X12)5.2412.585830.2796390.46464CrossoverLeg-RCPInletX12-X135.2412.5830.0012.09RCPOutlet-ColdLegX13-X144.12472.291672.090.001ColdLeg-Vessel InletjX19(X18-501)4.12472.2916700.1194UpperCorePlate-UpperPlenum845-86551.07640.03650.59150.5915Tuesday1 stMarch,2016:19:32,Page202of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.3SNPB,Question:1cSTPResponse:(Item1c,Page64)RefuelingWaterStorageTank(RWST)(LAREnclosure4-3,Ref.40,Page 6.3-32)Fulltankvolume,gal550,000*Minimumvolume(TechnicalSpeci"cation),gal458,000*

Boronconcentration(asboricacid),ppm2,800-3,000*Volumesincludeunusablevolume.2.2.4.4SNPB,Question:1dSTPResponse:(Item1d,Page64)Unit1-SecondaryMake-UpTank,gal300,000Unit2-SecondaryMake-UpTank,gal300,000 Unit1AuxiliaryFeedwaterStorageTank,TSmin,gal458,000 Unit2AuxiliaryFeedwaterStorageTank,TSmin,gal458,000SecondaryMake-UpTanksprovidenormal,non-safetyrelatedmakeupwatertothesecondaryside.

TheAuxiliaryFeedwaterStorageTankistheTSrequiredsafety-relatedwater sourceusedbytheAuxiliaryFeedwaterSystemtoremoveheatfromtheRCS viathesteamgenerators.2.2.4.5SNPB,Question:1eSTPResponse:(Item1e,Page64)Componentsofthe"ushing"owrateincludethecoldleginjection"owrate,hotleginjection"owrate,andvaporgenerationratethatwereextractedfrom theRELAP5-3D/MELCORsimulationofacoldlegdoubleendedguillotine (DEG)breakscenario,undernominaloperatingconditions.Detailsonthesim-ulationconditionsappliedareavailableinLAREnclosure4-3,Reference5,page 12.TheRELAP5-3Dnodalizationdiagramadoptedforthesimulationisde-pictedinFigure2ofLAREnclosure4-3,Reference5,page7.Thetotalcoldleginjection"owrate,thetotalhotleginjection"owrate,andthecorebrateareplottedinFigureA.Thesethermal-hydraulicpa-rametershavebeenestimatedasfollows:

• Thetotalcoldleginjection"owratewasestimatedasthesumofthecoldleginjection"owratefromeachofthesafetyinjection(SI)trains(sumof mass"owratesofthevalvecomponents149,249and349ofFigure2of LAREnclosure4-3,Reference5,Page7).

• Thetotalhotleginjection"owratewasestimatedasthesumofthehotleginjection"owratefromeachoftheSItrains(sumofmass"owrates ofthevalvecomponents148,248and348ofFigure2ofLAREnclosure 4-3,Reference5,page7).

• Thecorebratewascalculatedasthesumofvaporgenerationrateinallthenodesofthecore(Pipecomponents605and606(LAREnclosure4-3,Reference5,page5),total42nodes).ThevaporgenerationrateineachTuesday1 stMarch,2016:19:32,Page203of393 DRAFTPART2.RAIRESPONSES(ROUND1)nodewasestimatedbymultiplyingthevalueoftheparametervapgenbythevolumeofthenode.FigureA:RateofInjectionParametersacrosstheSimulationTable1:AverageInjectionandVaporGenerationBeforeandAfterSwitchtoSimulta-neousInjectionTimeIntervalColdLegInjection (lbm/s)HotLegInjection (lbm/s)VaporGeneration (lbm/s)15000s-SimultaneousInjection1615.500.00434.91 AfterSimultaneousInjection556.541107.420.75

Reference:

1.RELAP5-3DUsersManual,INEEL-EXT-98-00834.Tuesday1 stMarch,2016:19:32,Page204of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.6SNPB,Question:1fSTPResponse:(Item1f,Page64)HighHeadSafetyInjectionPumps(HHSI)(LAREnclosure4-3,Ref40,Page 6.3-31)Max.(run-out)"owrate,gal/min1,6002.2.4.7SNPB,Question:1gSTPResponse:(Item1g,Page64)TheboricacidstoragetanksarenotapartoftheSTPEmergencyCoreCool-ingSystem(ECCS),(LAREnclosure4-3,Reference40)andarenotconsidered withintheCASAGrandeAnalysis.2.2.4.8SNPB,Question:1hSTPResponse:(Item1h,Page64)TheboricacidstoragetanksarenotapartoftheSTPEmergencyCoreCool-ingSystem(ECCS)(LAREnclosure4-3,Reference40)andarenotconsidered withintheCASAGrandeAnalysis.2.2.4.9SNPB,Question:1iSTPResponse:(Item1i,Page64)ThetimetoemptytheRefuelingWaterStorageTank(RWST)(timetoinitiatethesumpswitchoverprocedure)wascalculatedusingtheRELAP5and MELCORinputmodelsdescribedin(LAREnclosure4-3,Reference5,page5).

Thevaluereportedbelowwascalculatedunderthefollowingconditions:

• Coldlegdoubleendedguillotine(DEG)break(27.5inchbreakinloop3)

• Nominalplantconditions(allSafetyInjection(SI)andContainmentSpray(CS)pumpsoperating)(Seenote)

• UsablevolumeoftheRWST(volumeofthewateruntilthelow-lowlevelalarmisreached)equalto413,735USgal.ThetimetoemptytheRWSTwasestimatedtobe:

TRWST=29.5minNote:Oneofthethreecontainmentspraypumpsmanuallysecuredatthebeginningofthetransient.

Reference:

1.STPMAAP4.04InputFile2.2.4.10SNPB,Question:1jSTPResponse:(Item1j,Page64)ContainmentpressurewascalculatedusingtheMELCORinputmodelde-scribedin(LAREnclosure4-3,Reference5,page8).Thepressurereportedwas calculatedunderthefollowingconditions

• Coldlegdoubleendedguillotine(DEG)break(27.5inchbreakinloop3)

• Nominalplantconditions(allSafetyInjection(SI)andContainmentSpray(CS)pumpsoperating)(LAREnclosure4-3,Reference5,page14)(See

Note)Tuesday1 stMarch,2016:19:32,Page205of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:ContainmentPressure(fromMELCORUpperCompartment)Thepressureofthecontainmentwasextractedasthetotalpressureoftheuppercompartment(node4oftheMELCORcontainmentmodelnodalization diagraminFigure4ofLAREnclosure4-3,Reference5,page9).ThecontainmentpressureresponseduringthetimebetweenthesumpswitchoverandthehotlegswitchoverisplottedinFigureA.Note:Oneofthethreecontainmentspraypumpsmanuallysecuredatthebeginningofthetransient.Tuesday1 stMarch,2016:19:32,Page206of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.4.11SNPB,Question:1kSTPResponse:(Item1k,Page64)Thesumpboricacidconcentrationovertimewasnotcomputed.However,thesumpboricacidconcentrationistightlycontrolled.Approximately88%of thesumpboricacidconcentrationisprovidedbytheRefuelingWaterStorage Tank(RWST)(between2800and3000ppm)andaccumulators(between2700 and3000ppm).Theremainingcontributiontoboricacidconcentrationcomes fromtheRCSwhichvariesbetween0and3500ppm.

Reference:

1.SouthTexasProjectNuclearOperatingCompany.Westinghouse.CN-CRA-97-094Rev.1.RequiredMassofTSPforLOCASumpSolutionpHAd-justment,November20082.2.4.12SNPB,Question:1l STPResponse:(Item1l,Page64)TheminimumtemperaturefordeterministicLOCAanalysisis50F.Thistemperatureisthedesignrangeminimumforthebuildingambienttemperature.

Reference:

1.SouthTexasProjectElectricGeneratingStation.MABHVACDesignBasisDocument5V109VB00110.Rev.3.TableT-8.Page266.2.2.4.13SNPB,Question:1m STPResponse:(Item1m,Page64)TheHighHeadSafetyInjection(HHSI)dischargetemperatureandtheLowHeadSafetyInjection(LHSI)dischargetemperaturewereextractedfromthe simulationresultsofa27.5inchcoldlegdouble-endedguillotine(DEG)break performedwithRELAP5-3D/MELCOR.InformationontheRELAP5and MELCORsimulationconditionsarereportedintheSumpSensitivityAnaly-sis(LAREnclosure.4-3,Reference.5,page.14)fornominalconditions.TheRELAP5nodalizationdiagramoftheEmergencyCoreCoolingSystem(ECCS)isdepictedinFigureAtofacilitatetheidenti"cationofthevolumes (nodes)wheretheliquidtemperaturewasread.BasedonthediagramofFigureA,thedischargetemperatureoftheHHSI(time-dependentjunctionx45)isthesameasthesumppooltemperature(tem-peratureoftheliquidinthetime-dependentvolumex91)becausenoheatstruc-turesweremodeledalongtheHHSI"owpath.ThedischargetemperatureoftheLHSI(time-dependentjunctionx46)wasreadastheliquidtemperatureattheexitofthepipecomponentx47,simulating theprimarysideoftheResidualHeatRemoval(RHR)heatexchanger.Theinjectiontemperature,resultingfrommixingoftheliquid"owsfromtheHHSIandLHSI,wasreadasthetemperatureoftheliquidinthemixingbranch (nodex60).FigureBshowsthedischargetemperatureoftheHHSI,thedischargetem-peratureoftheLHSI,andthetemperatureofthemixedliquidinjectedinthe primarysystemduringthetimebetweenthesumpswitchoverandthehotleg switchover.Tuesday1 stMarch,2016:19:32,Page207of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:RELAP5-3DSafetyInjectionNodalizationDiagram(X=loopnumber=2,3,or4)(LAREnc.4-3,Ref.5,Page7)2.2.4.14SNPB,Question:2aSTPResponse:(Item2a,Page64)SuctionLegDataInnerDiameter31CenterLineEl.225-5/16 BottomEL.ofID21.151 TopEL.ofID23.73(SeeresponsetoSNPB-RAI-2bforcoldleginformation).2.2.4.15SNPB,Question:2bSTPResponse:(Item2b,Page64)2.2.4.16SNPB,Question:2cSTPResponse:(Item2c,Page64)TopElevationofCore,ft26.796HeightofCore,ft14(SeetheresponsetoSNPB-RAI-1a)2.2.4.17SNPB,Question:2dSTPResponse:(Item2d,Page64)BottomElevationofDowncomer,ft10.81 (SeetheresponsetoSNPBRAI1a)Tuesday1 stMarch,2016:19:32,Page208of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureB:SafetyInjectionTemperature(FromSumpSwitchovertoHotLegSwitchover)ColdLeg,RCPDischargeInnerDiameter27.5CenterLineEl.323 BottomEL.ofID311.25 TopEL.ofID334.752.2.4.18SNPB,Question:3STPResponse:(Item3,Page64)Themaximumcoreaxial(AOs)forLOCAanalysesmustmeetthere-quirementsofthereloadsafetyanalysischecklist(RSAC)Item3.9perSTPNOC procedure0PEP01-ZE-0003"CoreReloadDesignProcess."TheRSACrequires aminimumAOof-20%andamaximumAOof15%forLOCA.Thecoresare designedtomeetTechnicalSpeci"cationlimitsofFxyandFn?HPowershapesarenotacoredesignparameter.AlthoughnotaSTPdesignbasis,basedonthedesignlimitsonAO,shapes(maximumalloweddesignLOCA AO)canbedevelopedforbottomandtopskewedaxialpowershapesusingthe followingconstraints:1.Power=0atbottomandtopofcore(nopowergenerationoutsideofcore) 2.Theintegralfrom0to0.5is1.2timesgreaterthantheintegralfrom0.5to1.0(bottom-skewed).Theintegralfrom0.5to1.0is1.15timesgreater thantheintegralfrom0to0.5(top-skewed).3.Theslopeismaximum(in"nite)atx=0(bottom-skewed),in"niteatx=1.0(top-skewed)4.Theslopeatx=1.0isnegative(bottom-skewed),slopeat0ispositive(top-skewed)Tuesday1 stMarch,2016:19:32,Page209of393 DRAFTPART2.RAIRESPONSES(ROUND1)5.Nopowersharing(fxyiseverywhere1.0),allchannelshaveexactlythesameaxialpro"le.Theparametersabovearechosentomaximizethepoweratthelowest(orhighestfortop-skewed)bysettingtheslopemaximumatx=0orx=1.0.Also,uniform radialpeakingwouldminimizechannel-to-channelmixing.Theresultingfunctionforbottom-skewedpro"lesis:

f (x)=11.09564432(x 0.80075524)(1x).Theresultingfunctionforbottom-skewedpro"lesis:

f (x)=5.2542(x 0.846098516)(1x)[shapehastobere"ectedsothatxrunsfrom1.0to0.0]Aconceptualillustrationofthefunctionsisshownbelow.TheactualminimumandmaximumAOsmeasuredforseveralcorecycleshasbeenwellwithinthecoredesignrequirements.STPNOCGuidelineREM-2CorePerformanceTrendingProgramrequiresmeasuredaxialtobe plottedforoverthecycleforUnits1and2.TheminimummeasuredAOforwas

-7.5%inUnit2andthemaximummeasuredAOwas6%inUnit1.2.2.4.19SNPB,Question:5 STPResponse:(Item5,Page65)Thesumpboricacidconcentrationovertimewasnotcomputed.However,thesumpboricacidconcentrationisrelativelyconstantastheconcentrationis tightlycontrolled.Approximately88%ofthesumpboricacidconcentrationis providedbytheRefuelingWaterStorageTank(RWST)(2800and3000ppm) andaccumulators(2700and3000ppm).Theremainingcontributiontoboric acidconcentrationcomesfromtheReactorCoolantSystem(RCS)whichvaries between0and3500ppm.TheRCScontributiontothesumpboricacidconcen-trationhaslittle

Reference:

1.SouthTexasProjectNuclearOperatingCompany.Westinghouse.CN-CRA-97-094Rev.1.RequiredMassofTSPforLOCASumpSolutionpHAd-justment.November2008.Tuesday1 stMarch,2016:19:32,Page210of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5SSIBResponses2.2.5.1SSIB,Transport:Question12 STPResponse:(Item12,Page70)Item5.a.4ofLAREnclosure5(Vol.6.2)wasaddedassupplementaryin-formationdescribingdetailsandassumptionsofthesupportingdebristransport calculation.Adescriptionofthehomogenouspoolmixingassumptionusedin theSTPCASAGrandeevaluationisprovidedintheresponsetoSSIBRAI11C inSTPlettertoNRCdatedMay22,2014,NOC-AE-14003103(ML14149A434).Becausehomogeneousmixingofall"neandsmalldebrisisassumed,thestatementoflocalretentionmadeinVol.6.2hasnoimpactondebristransport.

Debristransportdirectlytothesumpsunderpotentialsheeting"owduringpool "llisassessedasafractionofthedebristhatiscalculatedtoresideonthe"oor immediatelyafterthebreak.Similarly,theassumptionofhomogeneousmixing forall"neandsmalldebrisisnotbythedebrislocationfollowingpool

"ll.2.2.5.2SSIB,HeadLossandChemicalBump-up:Question 25aSTPResponse:(Item25a,Page76)Assumption7.fisaccurate.Thereisagapof2inchesfromthebottomofthestrainertothe"oor.Initially,thestraineraccumulates"beruniformly, includingthe2inchgap.Oncetheloadingtransitionstothecircumscribedarea andthe2-inchgapis"lled,(itphysicallycannolongeraccumulate"ber),the remainderofthestrainercontinuestoaccumulate"berinauniformmanner.

TheexistingSTPstrainerlayoutanddesignensuresthattheassumptionof uniformaccumulationofthetransporteddebrisoverallactiveportionsofthe strainerisvalid.Equations42and43(LAREnclosure4-3,page180)areusedtocalculatetheincrementalthicknessincreaseandcorrespondingdebrissurfacearea.Once the2-inchgapis"lled,"owisconsideredtoberestrictedandEquations42and 43calculateuniformdebrisaccumulationonallsidesofthestrainerexceptthe bottomwhere"owissettozero.Thisdecreasein"owsurfaceareainitially increasestheheadlosscomparedtoprevioustimestepswhenconsideringEqua-tion33(LAREnclosure4-3,page175).Assumption7.f(LAREnclosure4-3, page79)isusedtocalculatetheincrementaldebrisbedthicknessincreaseand debris("ow)areasusedintheheadlosscalculationsaccordingtoEquations40 through43(LAREnclosure4-3,page180).Totalstrainervolumetric"owrate dividedbyavailable"owareadeterminesapproachvelocityusedinthehead-loss

correlation.CASAGrandedoesnotcomparethedebrisheightonthetopofthestrainertothepooldepth.Intherareconditionthatthebedcanexceedthisheight,the currentevaluationallows"owareatoincreaseunrealisticallyatthetopofthe strainer.Althoughuncon"nedbedgrowthabovethepoolisnon-conservative, itwasstatedinAssumption7.fthatthisisanunlikelyoccurrence.Assumption 7.fcanbevalidatedbycomparingtheminimumpoolheight(inputdistribution lowerbound)andcorresponding"beraccumulationnecessarytoexceedthepool heighttotheprobabilitydistributionofdebrisvolume(seeresponsetoSSIB-Tuesday1 stMarch,2016:19:32,Page211of393 DRAFTPART2.RAIRESPONSES(ROUND1)RAI-26d).2.2.5.3SSIB,HeadLossandChemicalBump-up:Question 25bSTPResponse:(Item25b,Page76)ThisdoesnotAssumption7.e.Assumptions7.eand7.fareconsistentinthathomogeneouslymixeddebriswillaccumulateuniformlyontheas-designed STPstrainer.Initially,thestraineraccumulatesthehomogeneouslymixed"beruniformly,includingthe2-inchgap.Oncethe2-inchgapis"lled,(itphysicallycanno longeraccumulate"ber),theremainderofthestrainercontinuestoaccumulate "berinauniformmanner,andthe"owareaisadjustedtoaccountforlossof "owthroughthebottom.Becausethereisno"owsimulatedthroughthebottom ofthestrainerafterthetwo-inchgapis"lled,debriswillbehomogenouslymixed onallremainingsidesofthestrainerthatdosupport"ow.TheexistingSTPstrainerlayoutanddesignensuresthattheassumptionofuniformaccumulationofthetransporteddebrisoverallactiveportionsofthe strainerisvalid.2.2.5.4SSIB,HeadLossandChemicalBump-up:Question 26aSTPResponse:(Item26a,Page76)Yes,thestrainerloadingtableofSection5.6(LAREnclosure4-3,page181,Table5.6.3)includesareascalculatedforalldebrisloadingsincludingthetran-sitionfromthinbedstocircumscribedloads.Thistablewasusedtodetermineif thethin-bedloadingcriterionwasexceeded.Toevaluatesurfaceareasofdebris bedstransitioningfromthinbedtocircumscribed,thedebriswaslinearlyinter-polatedusingthearrivingdebrisvolumecalculatedusingmanufactureddensity.

Forthinbeds,theinterpolateddebrisvolumerangewasbetweenthe0and81.79

ft 3withacorrespondingarearangeof1,818.5and419.0ft2,respectivelyfromTable5.6.3(LAREnclosure4-3,page181).2.2.5.5SSIB,HeadLossandChemicalBump-up:Question 26bSTPResponse:(Item26b,Page76)TheincreaseindensityfromthemanufacturedvalueisnotaccountedforintheStrainerloadingtable(LAREnclosure4-3,page181).Thistableis basedonthicknessalone,andreportsassociatedareasandvolumes.Debriscom-pressionisaccountedforbythehead-losscorrelationthatprovidesane thicknessthatcanbeusedtointerpolatethetableto"ndesurfacearea.2.2.5.6SSIB,HeadLossandChemicalBump-up:Question 26cSTPResponse:(Item26c,Page76)Thegeneralarrangementofthestrainersdoesshowthatonesideofall3strainertrainsfacestheoutercontainmentwall,andthebottomsidefacesthe containment"oor.Oneofthestrainertrainsadditionallyhasastructuralwall approximately2to3feetaway.VisualinspectionoftheEmergencyCoreCooling System(ECCS)strainerperformancetesting(LAREnclosure4-3,Reference53,Tuesday1 stMarch,2016:19:32,Page212of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure8-6,Figure8-7,page47)showsthatevenincon"nedspaces(test"ume)thestrainersloadevenly.The"oorrepresentsanobstructionthatpreventscircumscribedloadingfromexceedingthe2-in.gapthatexistsbetweenthe"oorandthelowestedgeofthe strainers.Whenthisgapis"lled,thelowersurfaceisnolongeravailablefor "ow.Thestrainerloadingtablethenassumesthatdebrisaccumulationcontinues uniformlyinallunimpededdirections.2.2.5.7SSIB,HeadLossandChemicalBump-up:Question 26dSTPResponse:(Item26d,Page76)CASAGrandedoesnotcomparethedebrisheightontopofthestrainertothepooldepth.Intherareconditionthatthebedcanexceedthisheight, thecurrentimplementationallows"owareatoincreaseunrealisticallyatthe topofthestrainer.Althoughuncon"nedbedgrowthabovethepoolisnon-conservative,itwasstatedinAssumption7.fthatthisisanunlikelyoccurrence (LAREnclosure,4-3,page79).Assumption7.fisvalidatedbycomparingthe minimumpoolheight(inputdistributionlowerbound)andcorresponding"ber accumulationnecessarytoexceedthepoolheighttotheprobabilitydistribution ofdebrisvolume.Aminimumcontainmentpoolvolumeof39,533ft 3(inputdistributionlowerbound),andpoolareaof12,301ft 2wereusedintheCASAGrandeevaluation(LAREnclosure4-3,page45).Dividingthepoolminimumvolumebythepool areayieldstheminimumpossiblesampledpoollevelof3.2feetor38.6inches.

Subtractingtheheightofthetopofthestrainer28.5inches(LAREnclosure4-3, page63)fromtheminimumpoollevelgivestheminimumthicknessneededfor thedebristoreachthesurfaceofthepool(10inchesof"beraccumulation).This thicknessequatestoavolumeof328ft3necessarytoaccumulateonthestrainer tomeetorsurpasstheminimumpoollevelwheninterpolatedfromTable5.6.3.Complementarycumulativedensitydistributionsofthetotal"beramount(beforetransportfractionsareapplied)areillustratedinFigureAformany LatinHypercubeSampling(LHS)replicates,takenoverthefullbreaksizerange (SBLOCA,MBLOCA,andLBLOCA),usingtheZoneofIn"uence(ZOI)sizes describedinTable2.2.0(LAREnclosure4-3,page56).Thisquantityincludes latent"berandallZOIdestroyed"brousinsulationquantities.FigureBshows thatonacloserscaletheconditionalprobabilityofexceeding328ft 3of"brousdebrisislessthan10

-14.Tuesday1 stMarch,2016:19:32,Page213of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:CCDFofLDFGdebrisgenerated,beforetransportFigureB:CCDFofLDFGpresentandgenerated,beforetransport(zoomedin)Tuesday1 stMarch,2016:19:32,Page214of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.8SSIB,HeadLossandChemicalBump-up:Question 26eSTPResponse:(Item26e,Page76)Theinterstitialgapsofasinglestrainerare"lled(0.5inchdebristhickness)whenthevolumeofdebrismeetsorexceeds81.79ft3(LAREnclosure4-3, Table5.6.3).Complementarycumulativedensitydistributionsofthetotal"ber amount(beforetransportfractionsareapplied)areillustratedinFigureAfor manyLatinHypercubeSampling(LHS)replicatestakenoverthefullbreak sizerange(SBLOCA,MBLOCA,andLBLOCA),usingtheZoneofIn"uence (ZOI)sizesdescribedinTable2.2.0(LAREnclosure4-3,page56).Thisquantity includeslatent"berandallZOIdestroyed"brousinsulationquantities.Figure Bshowsonacloserscalethattheconditionalprobabilityofexceeding81.79ft 3of"brousdebrisislessthan10-14.Adatatickhasbeenaddedtothe"gurenear the81.79ft 3debrisvolume.NotethatLowDensityFiberglass(LDFG)volumesinthese"guresrepresentgenerateddebrisvolumes.Correspondingdebrisvalues thatreachthestraineraresmaller,sotheassociatedprobabilityofreachingthe circumscribedloadisalsosmaller.FigureA:CCDFofLDFGdebrisgenerated,beforetransportTuesday1 stMarch,2016:19:32,Page215of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureB:CCDFofLDFGpresentandgenerated,beforetransport(zoomedin)Tuesday1 stMarch,2016:19:32,Page216of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.9SSIB,HeadLossandChemicalBump-up:Question 26fSTPResponse:(Item26f,Page76)Asthedebris"llstheinterstitialvolumeofthestrainersthe"owareade-creasesfromthecleanstrainerareatothelimitinglowest"owareaofthecir-cumscribedfacessurroundingthestrainers.Asthe"owareadecreases,the"uid approachvelocity(U)increases(LAREnclosure4-3,Equation34,page176).

Thisincreasein"uidapproachvelocity(U)directlyincreasesthecalculated headloss(LAREnclosure4-3,Equation33,page175).2.2.5.10SSIB,NPSHandDegasi"cation:Question30 STPResponse:(Item30,Page77)No,thedegasi"cationcalculationdoesnotcreditcontainmentaccidentpres-sure.Inalldegasi"cationcalculations,bulksumpwatertemperaturesbelow212Fassumeatmosphericpressure(14.7psia).Atsumptemperaturesabove212F,thecontainmentpressureisassumedtobeequaltothevaporpressureofthe sumpwater.Theoveralltemperaturerangeusedforthedegasi"cationcalculation(s)is 102.5Fto177.5FforSBLOCAandMBLOCA.TheoveralltemperaturerangeforLBLOCAcalculationsis86.0Fto255.8FforLBLOCA.Therangewasdeterminedbybreaksizebasisandisbasedontime-dependentchangesinthe bulksumpwatertemperaturefromthetimeofrecirculationthroughsteady-statelong-termcooling(LAREnclosure4-3,Reference5).2.2.5.11SSIB,NPSHandDegasi"cation:Question31 STPResponse:(Item31,Page77)Reference56,TDI-6005-07,Vortex,AirIngestion&VoidFractionSouthTexasProjectUnits1&2.Revision3:November24,2008,evaluatesthepossi-bilityofthecollectionofgasbubblesintheSTPstrainer.WhileReference56 concludesthatthereisnoairingestionorvoidformation,CASAGrandecalcu-latesavoidfractionandappliestheresultsinthecalculationEmergencyCore CoolingSystem(ECCS)andContainmentSpraySystem(CSS)pumpNPSHr.AsstatedinSection2.2.28,theacceptancecriterionforasteady-stategasvoidfractionatthepumpsuctioninletis2%.CASAGrandeconservatively assumesthatanyvoidformedatthesumpstrainerisfullytransportedtothe ECCSorCSSpumpsuction,Assumption8.i.ThegeneraltransportofgasvoidsinthepipingbetweenthestrainerandECCSandCSSpumpsisexplainedinReference58,VTD-G927-0001.Units1 and2AcceptableGasVoidVolumesinECCSandRHRSuctionPiping.2.2.5.12SSIB,NPSHandDegasi"cation:Question32 STPResponse:(Item32,Page78)TheNPSHAmoduleofCASAGrandedoesnotincludecontainmentpressureabovethesaturationpressure,forcoolantvaporpressureconditionsgreaterthan standardatmosphericpressure.Fortemperaturesequivalenttooraboveboiling atstandardatmosphericpressure,thecontainmentpressureissetequaltothe saturationpressureofthe"uidfortheNPSHAcalculation.ForcontainmentTuesday1 stMarch,2016:19:32,Page217of393 DRAFTPART2.RAIRESPONSES(ROUND1)coolantvaporpressuresbelowboiling,thestandardatmosphericpressureof14.7psiisusedasthecontainmentpressure.2.2.5.13SSIB,NPSHandDegasi"cation:Question34 STPResponse:(Item34,Page78)Userenteredminimumandmaximumcontainmentspraysystem(CSS)"owratesareappliedasprobabilitydistributionbounds;thesmall,medium,and largebreakscenarioshavethesamebounds.Foreachsimulatedpipebreak,the probabilityspacebetweentheuserenteredminimumandmaximumsystem"ow ratesarerandomlysampledtodetermineoneindividualCSSpump"owrate forthescenario.TotalCSS"owrateisdeterminedbymultiplyingtherandom pump"owratebythenumberofoperableCSSpumps.CSS"owratesusedintheCASAGrandeevaluationareenteredasprob-abilitydistributionswithequalprobabilitybetweenuserenteredCSSpump minimumandmaximum"owrates.ThemaximumvalueissettotheFLOMAP calculatedaveragedesign"owsfortrainAandBoperationduringrecirculation (LAREnclosure4-3Reference42,pageA-39).Valuesotherthanthemaximumareappropriatebecausetheboundingmin-imum"owrates,usedasinputs,wereselectedfromsimulatedprobableevents (LAREnclosure4-3,Reference42,pageA-40)foreachoperable-trainstate(i.e.

3,2,or1trainoperable).CASAGrandeusesthehighertwo-trains-operation "owrates(LAREnclosure4-3,Table2.2.15,page54)foralleventswithtwoor threetrainsinoperation(Cases01,09,22and26).Eventswithonetrainopera-tion(Case43)usedtheirrespectiveminimumandmaximumvaluesfromTable 2.2.15(LAREnclosure4-3,page54)toboundtheirprobabilitydistribution.2.2.5.14SSIB,NPSHandDegasi"cation:Question35 STPResponse:(Item35,Page78)Thedoubleendedguillotinebreak(DEGB)valuescomputedbyEquation22ofLAREnclosure4-3(Section5.3.1,Page125)areusedonlytoassignDEGB breakstoaLOCAcategory(S,M,L).Foradoubleendedguillotinebreak,thebreakexitdiameter(D e))isequaltotheinnerdiameter(D i))ofthepipe.ADEGBwithfullseparationresultsintwojets(onefromeachrupturedsideofthepipe).Thus,thereareconceptually twobreakareasandtwobreakvolumes.Theequivalentdiameter(D DEGB)isdeterminedbydoublingthecrosssectionalareaofthebrokenpipeand"nding singleequivalentdiametertorepresentthetotalarea:

ADEGB=2 2 4 2DEGB 4=2 2 4DDEGB=2 D i2.2.5.15SSIB,In-VesselandBoricAcidPrecipitation:Question37STPResponse:(Item37,Page79)Tuesday1 stMarch,2016:19:32,Page218of393 DRAFTPART2.RAIRESPONSES(ROUND1)7.5g/fuelassembly(FA)of"berischosenasathresholdofconcernforboricacidprecipitation(BAP)basedonpreviousresults(LAREnclosure4-3, Reference[62])thatshowedverylittleheadlosswhen15g/FAwithafullamount ofchemicalprecipitateswereappliedduringhotlegbreak"owconditions.Witha debrisloadof7.5g/FA,thecoreisexpectedtoremainfullofwaterduringacold legbreak(CLB)eventhoughthereisnoopportunityforbypass"owcreditedin theanalysis.However,duringaCLB,attheselowdebrisamounts(7.5g/FA),

STPwouldhavesigni"cant"owthroughbypasspathways(LOCAholesandover thetopofthecorefrombypassregion)asdescribedintheLAR Enclosure4-1,Section2.1.2.LAREnclosure4-1,Section2.1.2describesthermal hydraulicanalysisofextremescenariosthatshowthecorewouldcontinuetobe suppliedwithadequate"owsuchthatcoolingispreserved,andthecorewould bere"oodedearlyinthetransient(ADAMSAccessionNo.ML14029A533).The7.5g/FAthresholdisappliedundertheassumptionoffulldebrisdepo-sitiononthefuelandtakesnocreditfordebristhatmayactuallydepositinthe bypass.TheCASAGrandeanalysisrecordsascenariofailure wheneveranequivalentinventoryof7.5g/FAentersthecore.STPfuelassem-bliesaredesignedwithasigni"cantgapbelowthebottomtieplatethatprovides alarge"owplenumbetweenthebottomoftheactivefuelandthetopofthe bottomcoreplate.The"ow-channeltobregionhasalargegap (approximately2inches)aroundtheentirecoreperipherythatisnotcredited forpossibledebrisretentionorforallowinglowconcentration"owtocirculate thoughthebypassregionthroughtheLossofCoolantAccident(LOCA)holes oroverthetopofthecore.STPhasshownthechemicalcontributiontoheadlossisinsigni"cantpriortohotlegswitchover(about6hours).BasedontheSTPreactordesign,basedon boundingexperimentalresultsfromboththeworkdoneinsupportofLAREn-closure4-3,page82of248,andfromReference(1),andbasedonboundingther-malhydraulicsimulationresultsforblockage,itisreasonabletouse7.5g/FA, de"nedbytestsusingaconservativechemicalload,asathresholdofconcern forBAP.Notethatthislimitisappliedtoallscenariosatalltimesregardless ofrealisticchemicalloadingandisthereforeconservativeeventhoughhigher thresholdscouldbeconsidered,particularlyearlyinthescenario.Althoughthe core-"berboronprecipitationthresholdcouldbereasonablydescribedasadis-tributionhavingameanmuchhigherthan7.5g/FA,theSTPLARappliedasharp,single-valuethresholdtomaintainclarityonthisreactorperformance metric.References

1.CHLE-012T1MBLOCATestReportRev4.Albuquerque,NM:UniversityofNewMexico,February18,2014.(ML14072A084)2.CHLE-014T2LBLOCATestReportRev3.Albuquerque,NM:UniversityofNewMexico,February22,2014.(ML14072A085)2.2.5.16SSIB,DebrisBypass:Question39a STPResponse:(Item39(a)iii,Page79)(i)The"berwaspreparedwithanARLmodi"edNEIprotocol(LAREnclo-sure4-3,Reference26,page16).Thegeneral"berpreparationprocedureTuesday1 stMarch,2016:19:32,Page219of393 DRAFTPART2.RAIRESPONSES(ROUND1)was(LAREnclosure4-3,Reference26,AttachmentA):(1)Ensuredrainvalveindebrispreparationtankisclosed.(2)Ensurethedebris"lterisinstalledonthereturnlinefromthetank.

(3)Weighoutthepredeterminedbatchsizeof"berandplaceintothescaledupdebrispreparationtank.(4)RecordquantityanddebrislotinformationinTable4.

(5)Filldebrispreparationtankwithwatertoatleasttheminimumdilu-tionspeci"edintheNEIdebrispreparationprotocol(0.72lbm/gal).

For2.4lbmof"ber,therecommendeddilutionbasedontheshake-downtestingresultsin30gal.(6)Startrecirculating"owpumpforthedebrispreparationtank.

(7)Ensurethepressurewashernozzlesareconnected.

(8)Changetheheightofthepressurewashernozzlestobewithin2inaboveorbelowthewatersurface.(9)Startthepressurewasherandrunapproximately15min(determinedfromshakedowntestingfor2.4lbmof"ber).(10)Examinedebrischaracteristicsforthebatchandnotethecom-mentssectiononthefollowingpage.Ifdebrischaracteristicsdo notmeetexpectations,applyhighpressuresprayforanextended durationasneeded,anddocumentincommentssection.(11)StopthepressurewasherandrecordtheactualtimeoverwhichthespraywasappliedinTable4.(12)Placeacleanbarrelunderthedebrispreparationtankanddraindebristhroughthevalveinthebottomofthetank.(13)Rinsetankwallsandensure"lterisfreeofdebris.

(14)Labelthebarrelcontainingthedebriswiththebatchnumberandde-brisweight.Anydeviationsfromthisprocedureweredocumentedfor eachtestinAttachmentAoftheSouthTexasPenetrationTestRe-port(LAREnclosure4-3,Reference26).Forexample,Tests1through 4interchangedsteps10and11whichwerenotedwithinkandini-tialmodi"cationsduringtesting.(ii)Analysistoquantitativelycharacterizethe"berafterpreparationandpriortotestingwasnotconducted.However,step10ofthe"berpreparation procedure,asdescribedaboveallowsthe"bertobehighpressuresprayed multipletimesiftheexpectationofthemostlyclass2"berswasnotmet.(iii)Step15of"berpenetrationtestprocedurerequiresgentlyre-mixingthedebrisusingamixingpaddlebeforethedebrisisintroducedinto thehopper/test"ume(LAREnclosure4-3,Reference26,AttachmentA).

Thedebrishopperalsointroducesadditionalmixingenergytothedebris beforeitentersthe"ume.Tuesday1 stMarch,2016:19:32,Page220of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.17SSIB,DebrisBypass:Question39bSTPResponse:(Item39b,Page79)Thesubsequentbatchof"berwasnotaddedtothetestuntilatleast5poolturnoverswerecompleted(LAREnclosure4-3,Reference26,page26).Sincethe testswereconductedatt"owrates,thedurationofapoolturnoveralso varied.Thedurationsof5poolturnoversforTests15,Test6,andTest7were11.8minutes,50.5minutes,and19.1minutes,respectively(LAREnclosure 4-3,Reference26,AttachmentA).2.2.5.18SSIB,DebrisBypass:Question39c STPResponse:(Item39c,Page79)Aschematicofthetestcon"gurationisbelow(LAREnclosure4-3,Reference26,page21).AtableofthedimensionscriticaltoqualityforTest1isshownonthesubsequent page(LAREnclosure4-3,Reference26,AttachmentA).Tuesday1 stMarch,2016:19:32,Page221of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.19SSIB,DebrisBypass:Question39dSTPResponse:(Item39d,Page80)Turbulencewasintroducedintothetesttankviamixers.Themixersprovidedenoughturbulencetosuspenddebrisinthetesttankandpreventdebrisfrom settlingtothe"oor(LAREnclosure4-3,Reference26,page16).Sincethe"ber remainedsuspended,alldebrisreachedthestrainer.2.2.5.20SSIB,DebrisBypass:Question39e STPResponse:(Item39e,Page80)ThetestsetupasdescribedinresponseSSIBRAI39censuresfull"owthroughthe"lterbagsduringthetest.Additionally,theNUKON Rwaspre-paredas"neshavingacharacteristicdiameterof7microns(LAREnclosure 4-3,Reference44,Table3-2).Thenominalporesofthebagsusedfor"ber collectionwas(were)5microns.Thelargerdiameter"nes,combinedwiththe randomorientationofthe"berasitcontactedthe"lterbag,suggeststhatdebris didnotbypassthe"lters.2.2.5.21SSIB,DebrisBypass:Question39f STPResponse:(Item39f,Page80)Yes,thepenetrationtestwasprototypicalwithrespecttotheSTPstrainer.Tuesday1 stMarch,2016:19:32,Page222of393 DRAFTPART2.RAIRESPONSES(ROUND1)ASTPprototypicalPCISure-Flostrainermodulewastested.The"owratewasscaledsuchthatthemaximumapproachvelocitiesofthetestsandtheSTP strainerwereequivalentat0.0086ft/s(LAREnclosure4-3,Reference26,Table 3,page19).Tests1through4weretestedwithatotalof2.4lbof"ne"brous debris;Tests5through7weretestedwithatotalof9.6lbof"ne"brousdebris (LAREnclosure4-3,Reference26,Table3,page19).TheDesignBasisAccident (DBA)testatARLinJulywasconductedwithatotalof5.5lbof"ne"brous debris(1).

Reference:

1.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportforECCSStrainerTestingJuly2008.RevisionA.11/24/2008.2.2.5.22SSIB,DefenseinDepthandMitigativeMeasures:Question 41aSTPResponse:(Item41a,Page81)Areductionin"owwilloccur(one(1)ContainmentSpraySystem(CSS)pumpsecured)beforeswitchovertorecirculationasdirectedbytheconditional informationpage(CIP)inSTPprocedure0POP05-EO-EO00,ReactorTrip orSafetyInjection(LAREnclosure4-3,Reference32).SecuringasingleCSS pumpwillconserveRefuelingWaterStorageTank(RWST)inventory.PerEOP 0POP05-EO-EO10,LossofReactororSecondaryCoolantallsprayscanbe securedafter6.5hoursbasedonIodinelevelslowenoughtosupporthabitability butcontainmentpressurewouldneedtobelessthan6.5psigandTSCconcur-rence.ConservationofRWSTvolumeandreductionofstrainer"owareboth bene"cialstrategiesforLOCAresponsethatcanbeachievedbysecuringspray

pumps.ThethirdCSSpumpisstoppedshortlyaftertheLOCAoccurs,beforetheRWSTisempty.Asaconsequence,whenrecirculationstarts,thattrainwill haveapproximately40%less"owthroughthestrainerresultinginmuchless debrisaccumulationandthereforeheadlosses(onthattrainsstrainer).StoppingaCSSpumpinthemostlikelyplantstatescenario(allCSStrainsrunning)isintendedtoconserveRWSTinventory.Additionally,the"owthrough theEmergencyCoreCoolingSystem(ECCS)strainerwillbereducedbyapprox-imately40%inthetrainthattheCSSpumpisstopped.Thisreductionintotal "owthroughthestrainerhastheadditionalbene"tofreducingdebrisbuildup onthatspeci"cstrainer.Apotentiallyadverseofsecuringspray"owis thatthelowerdebrisbedinventoryallowsmore"berpenetrationtothecore.Intherisk-informedmethodology,theofthereductionin"owistakenintoaccountasdescribedintheLAREnclosure4-2,SectionA.4.2,page83of257inthedescriptionofTopEventOFFS.Thestrainerloadingisaccountedfor asfoundinLAREnclosure4-3,Equations87through93page210of248and Section3page78of248(6e:Itwasassumedthatthedebristransporttoeachofthestrainersisproportionaltothe"owratethrougheachstrainerdividedby thetotal"owratethroughallofthestrainers.Thisisareasonableassumption sincethedebristransportswiththe"ow.

)Tuesday1 stMarch,2016:19:32,Page223of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.2.5.23SSIB,DefenseinDepthandMitigativeMeasures:Question 41bSTPResponse:(Item41b,Page81)STPNOCdidnotrevisetheEmergencyOperatingProcedure(EOP)Emer-gencyCoreCoolingSystem(ECCS)terminationcriteriatosecureanytrainsof safetyinjection.TheEOPsweremodi"edtosecureonetrainofContainment SpraySystem(CSS)ifallthreetrainsareinjecting.2.2.5.24SSIB,DefenseinDepthandMitigativeMeasures:Question 41cSTPResponse:(Item41c,Page81)No.STPNOCdoesnothaveaprocedureorguidancetoallowbackwashingoftheECCSstrainers.2.2.5.25SSIB,DefenseinDepthandMitigativeMeasures:Question 41dSTPResponse:(Item41d,Page81)AsstatedintheLAREnclosure4-1,pageC14theSTPEmergencyOp-eratingProcedures(EOPs)containstepstore"lltheRefuelingWaterStorage Tank(RWST).STPprocedure0POP05-EO-EO10"LossofReactororSecondary Coolant"directstheoperatortoenterprocedure0POP05-EO-ES13Transfer toColdLegRecirculation.0POP05-EO-ES13directstheoperatorstore"llthe RWSTinthestepfollowingcompletionoftransfertocoldlegrecirculation.

FollowingahypothesizedlargebreakLOCA,thiswouldoccurabout20to25 minutesfollowingthestartoftheevent.Themakeup"owratetoRWSTisapproximately150gpm.Thisequatestoapproximately11hourstomakeup100,000gallons.Theminimumvolume allowedintheRWSTbeforesecuringtheECCS/CSSpumpsis32,500gallons bytheprocedure.IntheunlikelyeventthatdebrispreventsrecirculationinallEmergencyCoreCoolingSystem(ECCS)trainsin11hours,theRWSTwouldbetlyfull ofwater.There"llrate(plusRWSTdraindown)wouldbeabletomeetcore coolingrequirementswithoutinterruptionoveralongperiodoftimeasshownin theLAREnclosure4-3,Table5.10.1page224of248.Thustheactionstore-"ll intheRWSTwillbeeforprovidinganalternativemethodofcooling watersupply.2.3ML14202A045,Thirdsetofresponses2.3.1APLABResponses2.3.1.1APLAB,CASAGrande-General:Question1a STPResponse:(Item1a,Page34)ThefollowingInputparameterSummaryTableprovides:a.Thebasisforusingapointestimateoradistribution.b.Thesourceoftheparametervalue(e.g.,licensingbasiscalculation).c.WhethertheparameterisbasedonanNRC-acceptedvalue(denotedby asterisk)Tuesday1 stMarch,2016:19:32,Page224of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThefollowingcategorizationsdfromVolume6.2,Table2.5.65.Thedis-crepancieshavebeenenteredintheSTPcorrectiveactionprogramtobead-dressedinanyfuturesubmittalofthisinformation.InputParameterVolume6.2,Table2.5.65RAIResponseTableTimetosecurecontainmentSprayFixedValueDistribution BlowdowntransportDistributionFixedValue WashdowntransportDistributionFixedValue FiberglasspoolerosionDistributionFixedValue Conventionalheadlossbump-upFixedValueDistribution Unquali"edCoatings(epoxy)NotincludedDistribution InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Timeto Recircu-lationFixedvaluesBreaksizeSwitchoverfromtheRWSTtoRecircula-tionisanautomaticfunction.Timetorecirculationasa functionofbreak sizeisbasedupon systemresistance (systemsline-ups),

RWSTvolumeandpumpperformance.Thesevaluesare"nite and"xed.Therefore, TimetoRecircula-tionisconsidereda "xedvalue(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013Timeto securecontain-ment SprayDistributionNoneOperatoractionstosecureonecontain-mentspraypumpand operatoractionsto securethecontain-mentspraysystem aredictatedbySTP OperatingProcedures 0POP05-EO-EO10,and0POP05-EO-ES11respectively.

Sincethistimeisde-pendentonoperator action,awindowof performancetimeisde"nedforeachac-tion.(32)0POP05-EO-EO10.LossofReactororSecondaryCoolant.(34)0POP05-EO-ES11.SITer-

mination.

(35)EmailfromTimSande (Alion)toKerryHowe(UNM) andErnieKee(STP).Best-EstimateTimeforSprayOper-ation:February23,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page225of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Timeto hotlegswitchoverDistributionNoneTimetothestartofhotlegswitchover is5.5hoursaftertheeventinitiationanddeterminedby monitoringplant conditionsviaSTP OperationProcedures

0POP05-EO-EO10.LossofReactororSecondaryCoolant and0POP05-EO-ES14.TransfertoHot LegRecirculation.

Plantconditionswill varybaseduponbreaksizeandoper-atingsafetysystems.

Timetothestartof hotlegswitchover is5.5hours.Itwas assumed(LAREncl.

4-3,Assumption1.j.),fromcommunicationwithplantpersonnel, thatthisactioncanbe completedwithin15 minutes.Itwassam-pledasadistribution ofequallylikelytimesbetween5.75and6hourstoaccountfor variationinoperator actiontimes.Since thetimetohotleg switchovermayvary slightlyandisbaseduponvariableplantconditionsitismod-eledasaprobability

distribution.(32)0POP05-EO-EO10.LossofReactororSecondary Coolant.

(36)0POP05-EO-ES14.Trans-fertoHotLegRecirculation.Containment Geome-tryFixedvaluesNoneThecontainmentphysicalcondition is"xedbaseduponas-builtconditionsasisthereforea"xed valueinput.(4)ALION-SUM-WEST-2916-01.CADModelSummary:

SouthTexasReactorBuildingCADModelforUseinGSI-191Analyses.Revision3:Novem-ber27,2012.

Break size andfre-quencyDistributionsBreakLocationAprobabilitydis-tributionisusedto modeltheLOCA frequencyforbreaksoftsizesattlocations withintheplant.

Breaksizeandfre-quencyareinherently variableandaprob-abilitydistributionmodelsthisvariabil-ity.

Statisticalsampling strategiesensure thattheDEGBcon-ditionsforevery pipe,discreteendpointsoffrequencydistributions,are explicitlyincludedin theevaluation.(4)ALION-SUM-WEST-2916-01.CADModelSummary:

SouthTexasReactorBuilding CADModelforUseinGSI-191 Analyses.Revision3:Novem-ber27,2012.(7)KNFConsultingServices LLC,andScandpowerRisk ManagementInc.Development ofLOCAInitiatingEvent FrequenciesforSouthTexas ProjectGSI-191FinalRe-portfor2011WorkScope.September2011.

(8)UniversityofTexasat Austin.ModelingandSam-plingLOCAFrequencyand BreakSizeforSTPGS1-191 Resolution.January23,2013.(9)Scandpower.RiskInformedGSI-191ResolutionLOCAFre-quencyComponentDatabase.

Revision2:October21,2011.

(37)NUREG-1829.Estimat-ingLoss-of-CoolantAccident (LOCA)FrequenciesThroughtheElicitationProcess:April 2008.continuednextpage...Tuesday1 stMarch,2016:19:32,Page226of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Poolvol-umeDistributionsBreakSizeTherearethreesourcesofwaterfor alossofcoolantaccident(LOCA):therefuelingwater storagetank(RWST),

thereactorcoolant system(RCS)and thesafetyinjection(SI)accumulators.Eachofthesources aremaintainedwithin speci"cvolume/mass

ranges.

Sincethereisarange ofvalues,theuseofadistributionratherthanapointvaluewas chosen.(14)ALION-CAL-STP-8511-01.STPPostLOCAWater VolumeAnalysis.Revision1:September20,2012.Pool areaFixedvalueNoneThisisaphysicalcon-ditionoftheplantand notvariable.There-forea"xedvalueis appropriate.(14)ALION-CAL-STP-8511-01.STPPostLOCAWater VolumeAnalysis.Revision1:

September20,2012.PoolTemper-atureFixedValuesBreakSizePooltemperaturewasselectedtobea"xed value.Onerepresen-tativetemperature historywaschosen torepresentsmallandmediumbreaks,andonerepresen-tativetemperature historywaschosen torepresentlarge breaksfromasuite ofthermalhydrauliccalculationsbasedonnominalconditions.

Alternativetemper-aturesunderfailure conditionswould havesuccessively lowerprobabilityofoccurrence.Nominalpro"leswere chosenbecauseitis notclearwhetherthe minimumormax-imumtemperature pro"lesareconserva-tiveduetocompetingfactors.Itwasalso assumedthatnominal temperaturepro"les aregenerallymore conservativedueto theshapeoftheirtransientbehavior(LAREncl.4-3, Assumption1.k.).(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:

January2013.*Containment pressureFixedvaluesPoolTemperatureFixedvalueswerecho-senbaseduponthe ASMESteamTables orassuminga"xedvalueof14.7psia.Saturationpressure attemperatureisa constant.Thisiscon-sistentwithaccident phenomenologyand USNRCguidelines.GeneralAssumptions1.c-Containmentpressurewasas-sumedtobe14.7psiaforall casesexceptwhenthepooltemperatureishigherthantheboilingtemperature.Incases wherethepooltemperatureis above212ûF,thecontainment pressurewasassumedtobe equaltothesaturationpres-sure.Thisisaconservativeas-sumptionsinceneglectingcon-tainmentoverpressurereduces theECCSpumpNPSHmargin andincreasestheamountofde-gasi"cationatthestrainer.Operating pumpsFixedvaluesNoneThenumberofoper-atingpumpsisconsid-ereda"xedvalueandaspeci"cdesigninput asapplicabletoeach plantfailurestate.(38)STP-2699325-O-03.Sub-ject:OntheFrequencyofSuc-cessStatesInvolvingtNumbersofPumpsOperating.

December18,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page227of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Low headsafety injection "owrateFixedvaluesBreakSize,PumpsRun-ningFlowrateisspeci"cvaluedeterminedby operatingpumps(seeabove)andaspeci"cdesigninputasap-plicabletoeachplant failurestate.These operatingline-upsare "xed.Therefore,sys-tem"owrateiscon-sidereda"xedvaluethatisdeterminedby thenumberofoperat-ingpumpsandbreak

size.(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013.

(41)MC-6220.SI&CSPump NPSH.Revision4:February5, 2002.High headsafety injection "owrateFixedvaluesBreakSize,Pumpsrun-ningFlowrateisspeci"cvaluedeterminedbyoperatingpumps(seeabove)andaspeci"c designinputasap-plicabletoeachplant failurestate..These operatingline-upsare "xed.Therefore,sys-tem"owrateiscon-sidereda"xedvalue thatisdeterminedby thenumberofoperat-ingpumpsandbreak

size.(5)TexasA&MUniversityDe-partmentofNuclearEngineer-ing.SumpTemperatureSensi-tivityAnalysis.Revision2.0:January2013.

(41)MC-6220.SI&CSPump NPSH.Revision4:February5, 2002.Containmentspray"owrateDistributionsPumpsRunningIfcontainmentspraysareinitiated,the"owrateisnotdepen-dentonthesizeof thebreak.Flowrate variesdependingon thenumberoftrains inoperation.Thenumberoftrainsinoperationisdis-tributedoverthe rangeofbreaksizes andoperatingtrains.

Basedonthedis-tributedbreaksizesthecontainmentspray"owrateisinputasa

distribution.(41)MC-6220.SI&CSPumpNPSH.Revision4:February5, 2002.(42)5N109MB01024.Design BasisDocumentContainment Spray.Revision3:November 17,2004.*Quali"ed coatings quantityFixedvaluesNoneThequali"edcoatingquantitiesarebased onacombinationof plantcon"gurationandNRCapprovedanalysismethods.

Quali"edcoatings quantitiesarecon-sidered"xedvalues astheyarebasedon speci"cconservativebreakscenarios.(11)ALION-CAL-STP-8511-03.STPQuali"edCoatings DebrisGeneration.Revision0:

August10,2012.

• Unquali"ed coatings quantity (non epoxy)FixedvaluesNoneTheunquali"edcoatingquantities (non-epoxy)arebased onacombinationof plantcon"gurationandNRCapprovedanalysismethods.

Unquali"edcoatings quantitiesareconsid-ered"xedvaluesas theyarebasedoncon-servativeassumptionsregardingunquali"edcoatingdegradation.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:

November26,2012.continuednextpage...Tuesday1 stMarch,2016:19:32,Page228of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)*Unquali"ed

coatingsquantity(epoxy)DistributionNoneTheunquali"edcoat-ingquantitiesare basedonacom-binationofplantcon"gurationand NRCapprovedanaly-sismethods.

Epoxyunquali"ed coatingsquantitiesareconsideredadistributionand arebasedonthe EPRIandCarboline

analysis.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:November26,2012.

• Unquali"ed coatings failure timeFixedvaluesNoneThetimeafterthestartoftheLOCAeventthattheunqual-i"edcoatingfailsis determinedbyanaly-sisofdatapresented intheEPRItestre-portDesignBasisAc-cidentTestingofPres-surizedWaterReac-torUnquali"edOrigi-nalEquipmentManu-facturerCoatings.Fi-nalReportSeptember

2005.

Timingisinputasa"xedvalueasitisagivenspeci"cdesign

parameter.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:November26,2012.

CrudquantityFixedvalueNoneThisisaphysical"xedvaluebasedon industryboundinges-timatesoftheamountofcrudavailablewithintheReac-torCoolantSystem andsteamgenerator tubes.Thisamount doesnotvarywith breakselectionandisthereforeinputasa"xedvalue.Acknowl-edgedvariationsin thisparticulatesource donotcompetewith dominantsources likefailedunquali"ed coatings.(13)ALION-CAL-STP-8511-07.STPCrudDebrisGenera-tion.Revision0:November12, 2012.*Latent debris quantityFixedvaluesNoneThelatentdebrisquantitiesarebased onacombination ofplantcon"gura-tion,conservative assumptionsandNRCapprovedanalysismethods.

Latentdebrisquan-titiesareconsidered "xedvaluesasthey arebasedonassumed plantconditions.(43)ALION-CAL-STPEGS-2916-002.GSI191Contain-mentRecirculationSump Evaluation:DebrisGeneration.

Revision3:October20,2008.

• Miscellaneous debris quantityFixedvalueNoneMiscellaneousdebrisquantitiesarebased onacombination ofplantcon"gura-tion,conservative assumptionsandNRCapprovedanalysismethods.

Miscellaneousdebris quantitiesarecon-sidered"xedvalues astheyarebased onassumedplant conditions.(43)ALION-CAL-STPEGS-2916-002,GSI191Contain-mentRecirculationSump Evaluation,DebrisGeneration.

Revision3:October20,2008.continuednextpage...Tuesday1 stMarch,2016:19:32,Page229of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Miscellaneous

debris failure timeFixedvalueNoneMiscellaneousdebriswasassumedtofail atthebeginningoftheevent.Itisthereforeconsidered a"xedvalueinput.

Miscellaneousdebris failuretimeincludes bothcrudandlatent debris.DebrisGenerationAssump-tions,4.b-Itwasassumed that100%ofthemiscellaneousdebris(tags,labels,etc.)wouldfailatthebeginningofthe event.Thisisaconservative assumptionsincethemajority ofthemiscellaneousdebris wouldbeoutsidetheZOIand maynotfailatallduringtheevent.*Insulation ZOIsizeFixedvaluesBreakSize,InsulationLo-cationInsulation-speci"cZOIsizeshavecom-monlyaccepted conservativedef-initionsthatare consistentwiththoseusedforstrainerdesign.Plausible reductionsinZOI sizehavenotbeen de"nitivelydemon-stratedbytesting,sodeterministicZOIsizeswereadoptedas "xedvalueinputs.(44)NEI04-07Volume1.PressurizedWaterReactor SumpPerformanceEvaluation Methodology.Revision0:

December2004.

(45)NEI04-07Volume2.SafetyEvaluationbytheOf-"ceofNuclearReactorRegu-lationRelatedtoNRCGeneric Letter2004-02,NuclearEn-ergyInstituteGuidanceRe-port"PressurizedWaterReac-torSumpPerformanceEvalua-tionMethodology".Revision0:December2004.*Fiberglasssizedis-tribu-tionFixedvaluesBreakSize,InsulationLo-cationThe"berglasssizedistributionisaspe-ci"cdesigninputto theanalysis.TheZOIsizesdonotchargeandthereforesize distributionsarealso considered"xedvalue

inputs.(46)ALION-REP-ALION-2806-01.InsulationDebris SizeDistributionforUsein GSI-191Resolution.Revision4:May20,2009.

Debrischarac-teristicsFixedvaluesNoneThephysicalchar-acteristicsofdebris,i.e.density,materialcomposition,etc.are derivedfrommanufac-turersdata.Asthe physicalcharacteris-ticsdonotvarywith accidentscenario,theyareconsidered"xedvalues.(11)ALION-CAL-STP-8511-03.STPQuali"edCoatings DebrisGeneration.Revision0:August10,2012.(12)ALION-CAL-STP-8511-06.STPUnquali"edCoatings DebrisGeneration.Revision2:

November26,2012.

(13)ALION-CAL-STP-8511-07.STPCrudDebrisGenera-tion.Revision0:November12, 2012.

(43)ALION-CAL-STPEGS-2916-002.GSI191Contain-mentRecirculationSump Evaluation:DebrisGeneration.Revision3:October20,2008.

• Chemical product forma-tion timeFixedvaluesNoneChemicalproductformationtimeisset toa"xedvalue,zero (0.0),sothatoppor-tunityforchemical productformationexistsatalltimesduringallscenarios.

TheparameterChem-icalPrecipitation Temperaturecontrols theactualtimewhen chemicalinducedhead-lossareintroduced.(20)CHLE-016.CalculatedMaterialRelease.Revision1:

January10,2013.*Blowdown trans-portFixedValuesBreakLocation,Debris SizeWhileblowdowntransportisafunction oftheeventandvaries witheachevent,asdescribedinALION-CAL-STP-8511-08, conservative"xed valueswereadopted toaidunderstanding ofcomplextransport logicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.continuednextpage...Tuesday1 stMarch,2016:19:32,Page230of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)*Washdown trans-portFixedValuesSpraysinitiated,Debris SizeWhilewashdowntransportisafunction oftheeventandvarieswitheachevent,asdescribedinALION-

CAL-STP-8511-08, conservative"xed valueswereadopted toaidunderstanding ofcomplextransportlogicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.*Pool"ll trans-portFixedvaluesBreakLocation,Debris SizeTheanalysisassumesthatalllatentdebris andZOIdebrisintro-ducedat"oorlevelis subjecttotransporttoinactivecavitiesandtothestrainers duringpool"ll.Al-thoughuncertainties existintheaccepted methodology,"xed valueswereadoptedtoaidunderstandingofcomplextransport logicsequences.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.

• Recirculation trans-portFixedvaluesBreakSize,BreakLoca-tion,DebrisType,Debris

SizeThevarioustypesandsizesofdebris transporttly duringtheblowdown,washdown,andpool"ll-upphases.The spatialdistribution ofthisdebrisatthe startofrecirculation couldvarywidely becauseinsulationde-brisonthepool"oorwouldbescattered aroundbythebreak "owasthepool"lls, anddebrisinupper containmentwould bewasheddownatvariouslocationsbythespray"ow.To approximatethis complexity,conserva-tivefractionsof"ne andsmalldebris(and allparticulates)areassumedtobehomo-geneouslymixedand availablefortransport byECCSrecircula-tion"owde"nedby thenumberofpumps operating.Therefore,recircu-lationtransportis consideredas"xed values.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.*Fiberglassspray erosionFixedvalueSpraysinitiatedFiberglasssprayero-sionisbasedupon testdata.Spray"owrateisapproximatelyconstant.Therefore Fiberglasssprayero-sionisconsidereda "xedvalue.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.*Fiberglasspoolero-sionFixedvalueNoneFiberglasssprayero-sionisbasedupontestdata.Pool"owveloc-itiesvarybasedupon thephysicalcon"gu-rationoftheSTPcon-tainment.Toapproxi-matethiscomplexity, asingleconservativevalueofsprayerosionisassumed(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.(new)ALION-REP-ALION-1006-04.ErosionTestingof SmallPiecesofLowDensity FiberglassDebrisTestRe-port.Revision1:November7, 2011.continuednextpage...Tuesday1 stMarch,2016:19:32,Page231of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Fiberglass poolero-sion timeFixedvaluesNoneFiberglasspoolerosionisasmall additionalfractionofthetotal"ne"beravailablefortrans-port,sothetotal expectedquantity oferoded"berwas introducedtothepoolpriortorecirculationasa"xedvalue.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.Revision2:January21,2013.(new)ALION-REP-ALION-1006-04.ErosionTestingof SmallPiecesofLowDensity FiberglassDebrisTestRe-port.Revision1:November7, 2011.Transport timeFixedvaluesSumpFlowRate,PoolVol-ume,FailureTimeTransporttimeisbaseduponevent timingandpump"ow rateswhichhaveas-signeddistributions.

Becausetransporttimeiscalculatedprescriptively,itis describedhereas a"xedvalue,even thoughtransporttime dependsonrandom factors.(23)ALION-CAL-STP-8511-08.Risk-InformedGSI-191 DebrisTransportCalculation.

Revision2:January21,2013.

Strainer geome-tryFixedvaluesNoneStrainergeometryisbasedupontheplant physicalconditionand isadirectnumerical input.Itwastherefore inputas"xedvalues.(47)SFS-STP-PA-7101.SouthTexasProjectUnits1&2Sure-FlowStrainerModuleDetails.

Revision5:September5,2006.

(48)TDI-6005-01.SFSSurface Area,FlowandVolumeCalcu-lations.Revision1:August31, 2006.

(49)SFS-STP-GA-00.South TexasProjectUnits1&2 Sure-FlowStrainerGeneral Arrangement.Revision4:

September7,2006.(50)SFS-STP-PA-7103.SouthTexasProjectUnits1&2Sure-FlowStrainerSectionsandDe-tails.Revision2:August4, 2006.

(51)2F369PS10572Sheets3,4

&6.SafetyInjectionSl(52)5L019PS0004.Speci"ca-tionforCriteriaforPipingDe-signandInstallation.Revision 23:s.n.Geometric strainer loadingFixedvaluesStrainergeometryGeometricstrainerloadingisbasedupon thestrainerphysicalgeometry.Itisadi-rectnumericalinput.

Itwasthereforeinput as"xedvalues.(47)SFS-STP-PA-7101.SouthTexasProjectUnits1&2Sure-FlowStrainerModuleDetails.Revision5:September5,2006.(48)TDI-6005-01.SFSSurface Area,FlowandVolumeCalcu-lations.Revision1:August31, 2006.

(49)SFS-STP-GA-00.South TexasProjectUnits1&2Sure-FlowStrainerGeneralArrangement.Revision4:

September7,2006.

Clean strainer head lossFixedvalueNoneCleanstrainerheadlossisahydraulic attributebasedupon thephysicaldimen-sionsofthestrainer.Itisthereforea"xed value.(53)66-9088089-000.SouthTexasProjectTestReport forECCSStrainerTesting.

Revision0:August29,2008.

Thin-bed thick-nessFixedvalueNoneThethin-bedthick-nessis1/16thof aninch.Thisisa physical"xedvalueassumption.Uncer-taintyregardingthe exactvalueofthis transitionthicknessis beingaddressedusing parameterstudies ratherthandirectpropagationofa distribution.DebrisGenerationAssump-tions,7.c-Itwasassumedthat a"berbedofatleast1/16thof aninchisnecessarytocapture chemicalprecipitates.Thisisareasonableassumptionsinceathinnerdebrisbedwouldnot fullycoverthestrainerand wouldnotsupportappreciable headlossesduetochemical

debris.continuednextpage...Tuesday1 stMarch,2016:19:32,Page232of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Conventional headloss bump-upDistributionNoneAccuracyofthe NUREG/CR-6224 correlationisknowntovarywithrespecttodebriscomposition.

Also,knowndefects intheconventional implementationof theequationraisequestionsregardinggeneralapplicability.

Toaccountforthe presenceofextreme conditionsinthesce-nariosamplespace, exponentialprobabil-itydistributionswerede"nedandapplied asdirectmultipliers totheestimatedcon-ventionalheadloss.

Becauseconsensus ontheseissuesistoestablish,theconventionalhead lossbump-upisinput asadistribution.Section5.6.2,ConventionalDe-brisHeadLossModel-The NUREG/CR-6224correlation wasselectedfortheCASAcomputationofconventionaldebrisheadlossacrossthe strainer.Thiscorrelationis asemi-theoreticalheadloss modelandisdescribedindetail inAppendixBofNUREG/CR-6224 Chemicalheadloss bump-upDistributionsBreakSizeThecorrosionanddissolutionrelease modelandthesol-ubilitymodelwerenotdirectlyimple-mentedinCASA Grande.Therefore,a setofchemical bump-upfactorprob-abilitydistributionsweredevelopedandappliedforallbreaks.

Toaccountforthe presenceofextreme conditionsinthesce-nariosamplespace, exponentialprobabil-itydistributionswerede"nedandapplied asdirectmultipliers totheestimated conventionalhead loss.Theprobability distributionswerede-velopedbasedonthecurrentresultsfrom theCHLEtestingand onchemicalhead-lossobserved duringSTPstrainer

testing.(20)CHLE-016.CalculatedMaterialRelease.Revision1:

January10,2013.

Pump NPSH requiredFixedvaluesVoidFractionThisisaphysicalcharacteristicofthe pump.Fixedvalues werede"nedbythe pumpvendorare thereforeinputas "xedvalues.(25)ALION-CAL-STP-8511-05.STPNetPositiveSuction HeadMargin.Revision0:

November19,2012.

Pump NPSH availableFixedvaluesPoolTemperature,PumpFlowRate,PoolLevel, ContainmentPressurePumpNPSHavailableisde"nedinALION-

CAL-STP-8511-05.

Theyaretherefore inputas"xedvalues.(25)ALION-CAL-STP-8511-05.STPNetPositiveSuction HeadMargin.Revision0:

November19,2012.

Strainer struc-tural marginFixedvalueNoneStrainerstructuralmarginvaluesareme-chanicalpropertiesof thestrainermaterial andcodeallowables.

Theyaretherefore inputas"xedvalues.

Also,seetheresponsetoEMCB-RAI-1pro-videdtotheNRC inSTPletter

NOC-AE-13003065, datedDecember23, 2013(ML14015A311).(54)EC-PCI-STP-6005-1001.AESDocumentNo.PCI-5473-SO1Rev2"StructuralEvaluationofStrainersfor ContainmentEmergency Sumps".Revision2:January 7,2010.

(55)EC-PCI-STP-6005-1004.

AESDocumentNo.PCI-5473-S03Rev0"StructuralEvaluationofStrainersfor ContainmentEmergency SumpsforLongTermPost LOCACase".Revision0:

January7,2010.continuednextpage...Tuesday1 stMarch,2016:19:32,Page233of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Containment relativehumid-ityFixedvalueNoneContainmentrelativehumiditywasassumed tobe100%.Thisisa"xedvalueanddoesnotchangethrough-outtheanalysis.DebrisGenerationAssump-tions,8.e-Itwasassumed thattherelativehumidityofthecontainmentatmosphereis 100*Pumpgasvoid limitsFixedvalueNonePumpgasvoidlimitsareasde"nedin USNRCRegulatory Guide1.82.WaterSourcesforLong-TermRecirculation CoolingFollowing aLoss-of-Coolant Accident.Thisisa "xedvalue.(59)RegulatoryGuide1.82.WaterSourcesforLong-Term RecirculationCoolingFollow-ingaLoss-of-CoolantAcci-dent.Revision4:March2012.Fiber"l-tration parame-tersDistributionsNoneFiber"ltrationofastrainerisafunctionofthemassofdebris onthestrainer.STP-speci"ctestingwas usedtoderivepa-rametersofthe"ltra-tionmodelandtheirassociateduncertain-ties.Therefore,the "ber"ltrationparam-etersareinputasa distributionbasedon testdata.(60)UniversityofTexasatAustin.FiltrationasaFunc-tionofDebrisMassontheStrainer:FittingaParametric Physics-BasedModel.s.l.June 5,2013.Fiber shedding parame-tersDistributionsNoneFibersheddingisafunctionofthe massofdebrisonthe strainer.STP-speci"c testingwasusedto deriveparametersof thesheddingmodelandtheirassoci-ateduncertainties.

Therefore,the"ber sheddingparame-tersareinputasa

distribution.(60)UniversityofTexasatAustin.FiltrationasaFunc-tionofDebrisMassonthe Strainer:FittingaParametric Physics-BasedModel.s.l.June 5,2013.Boil"owrateFixedvaluesNone"owratesareafunctionoftimeandofcorepowerandare basedonthephysi-calplant.Boil"ow ratewerethereforein-putas"xedvalues.(61)5N079NB01000(WCAP-12381).STPNOCDesignBa-sisDocumentAccidentAnaly-sis.Revision15:July29,2009.

(62)TechnicalSpeci"cations Section1.27.RatedThermal Power.Unit1AmendmentNo.

154;Unit2AmendmentNo.142:s.n.Number offuel assem-bliesFixedvalueNoneThenumberoffuelas-sembliesisaphysical plantparameterand doesnotvary.Itwas thereforeinputasa "xedvalue.(61)5N079NB01000(WCAP-12381).STPNOCDesignBa-sisDocumentAccidentAnaly-sis.Revision15:July29,2009.

• Coreblockage "ber limitsFixedvaluesBreakLocation,InjectionPathThermalhydrauliccalculationsofcore blockageprovided screeningcriteria thatrenderedthe coreblockagelimits obsoletefortheSTPanalysis.Coreblock-age"berlimitswere thereforeinputas "xedvaluesrepresent-ingextremelimitsof acceptableblockage.(63)WCAP-16793-NP.Evalu-ationofLong-TermCoolingConsideringParticulate,Fi-brousandChemicalDebrisin theRecirculatingFluid".Revi-sion2:October2011.continuednextpage...Tuesday1 stMarch,2016:19:32,Page234of393 DRAFTPART2.RAIRESPONSES(ROUND1)...continued InputParame-terDistribution(s)orFixedValue(s)DependenciesBasisReference(s)(fromLAREnc.

4-3)Boron precip-itation"ber limitsFixedvaluesBreakLocation,InjectionPathTheboronprecip-itation"berlimits areinherentlyuncer-tainbecauseofbothphysicalvariability andlackofknowledge regardingassociated phenomena.The boronprecipitation "berlimithasbeenidenti"edasakeyfactorcontrolling theriskofECCS failure.Itis toachieveconsensus regardingevenasinglevalueofthisimportantthreshold, letaloneastatistical distribution,boron precipitation"ber limitsweretherefore inputas"xedvaluesandtheimpacthasbeenemphasizedvia parameterstudies.(new)LetterfromSherBa-hadur(NRC)toAnthony Nowinowski(PWROG).Fi-nalSafetyEvaluationforPressurizedWaterReactorOwnersGroupTopicalReport WCAP-16793-NP,Revision 2,"EvaluationofLong-Term CoolingConsideringPartic-ulateFibrousandChemical DebrisintheRecirculatingFluid"(TACNo.ME1234):April8,2013.2.3.1.2APLAB,CASAGrande-General:Question1bSTPResponse:(Item1b,Page34)SeetheresponsetoAPLAB,CASAGrande-General:RAI1a.2.3.1.3APLAB,CASAGrande-General:Question1c STPResponse:(Item1c,Page34)SeetheresponsetoAPLAB,CASAGrande-General:RAI1a.2.3.1.4APLAB,CASAGrande-PlantCon"guration:Question1a STPResponse:(Item1a,Page35)Yes,varyingtheaforementioned(orother)parametersfromtheirnominalvalueswillproducetime-temperaturecurvesyieldinghigherconditionalproba-bilitiesofsumpandcoreblockageAsanexample,asummaryoftheStrainerMappingforRCFCsisshowninFigure1.2.3.1.5APLAB,CASAGrande-PlantCon"guration:Question1b STPResponse:(Item1b,Page35)Asstatedpreviously,pooltemperaturehasaneonmanyaspectsoftheoverallGSI-191evaluationincludingchemical(materialreleaseratesand solubilitylimits),debristransport,strainerheadloss,NPSHmargin,degasi"-

cation,andin-vesseleInsomecases,ahigherpooltemperaturepro"leis moreconservative(e.g.,NPSHmarginanddegasi"cation),inothercasesalower pooltemperaturepro"leismoreconservative(e.g.,strainerheadlossanddebris transport).Withrespecttopooltemperature,duetoitscompetingandcomplexityofontheoverallevaluation,itisnotpossibletopre-determinewhethera higherorlowerpooltemperaturepro"lewouldbemorelimitinginthedetermi-nationofCDForLERF.Thepremiseofarisk-informedevaluationistoconsideraholisticapproachwherecompetingecollide.Theuseofnominalpooltemperaturepro"lesisTuesday1 stMarch,2016:19:32,Page235of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:StrainerMapping.Frequenciesrepresenttheplantcon"gurationconditionedonLOCAFrequency.Frequencies

<1E-14(PRAtruncationfrequency)arereportedas zero.consistentwithaholisticrisk-informedapproachandprovidesamorerealisticevaluationofrisk.2.3.1.6APLAB,CASAGrande-PlantCon"guration:Question2a STPResponse:(Item2a,Page35)Yes,varyingtheaforementioned(orother)parametersfromtheirnominalvalueswillproduce"owratesyieldinghigherconditionalprobabilitiesofsump andcoreblockage.Asanexample,asummaryoftheStrainerMappingfor RCFCsisshowninFigure1.2.3.1.7APLAB,CASAGrande-PlantCon"guration:Question2b STPResponse:(Item2b,Page35)Thepremiseofarisk-informedevaluationistoconsideraholisticapproachwherecompletingorwidelyvaryingprovideoverlyconservativeandcom-petingresults.Theuseofnominal"owratesprovidesamorerealisticevaluation, isconsistentwithaholisticrisk-informedapproachandprovidesamorerealistic evaluationofrisk.Thegoalistoprovideareasonableprobability,notnecessarily amaximizationoftheprobabilityoffailure.Tuesday1 stMarch,2016:19:32,Page236of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:StrainerMapping.Frequenciesrepresenttheplantcon"gurationconditionedonLOCAFrequency.Frequencies

<1E-14(PRAtruncationfrequency)arereportedas zeroItisrecognizedandhasbeenstatedpreviously,that"owrateisoneofthemoreimportantinputparametersandhasanonmanyaspectsofthe overallGSI-191evaluation.Insomecases,ahigher"owincombinationwith otherfactorsproducesamoreconservativeresult.Inothercasesalower"ow incombinationwithotherfactorsproducesamoreconservativeresult.Using nominalvaluesprovidesresultsthatarereasonable,probableandthatmaybe usedinaholistic,risk-informedevaluation.2.3.1.8APLAB,CASAGrande-PlantCon"guration:Question3a STPResponse:(Item3a,Page35)Pumpstate22,thecasewhenonehighhead,onelowheadandonespraypumpisunavailable,waschosentoexploretheimpactoftheassumptionthat allfailedpumpsareonthesametrain.Pumpstate22waschosenfordetailed examinationasitisthemostlikelypumpstateinvolvingmultiplepumpfailures.Pumpstate22assumesthatallthreeunavailablepumpsareonthesametrain.Toexploretheimpactofunavailablepumpsbeingondttrains,four additionalcaseswereevaluated.Theresultsofthisanalysisindicatedthatthecon"gurationwhereallunavail-ablepumpsareonthesametrainleadstothehighestlikelihoodoffailureatthe sump.Threeoftheadditionalcasesinvestigatedthatinvolvedthreeunavailable pumpsbutonttrainsdidresultinconditionalfailurelikelihoodshigher thanpumpstate22.Intwoofthosecases,ahighercoredamagefrequency duetoin-vesselphenomenawaspredicted.ThelargerincreaseincoredamageTuesday1 stMarch,2016:19:32,Page237of393 DRAFTPART2.RAIRESPONSES(ROUND1)frequencyresultingfromthesetwocaseswasapproximately1.5%Detailsdocumentingtherationaleforselectingpumpstate22todemonstratetheimpactoftheassumption,theanalysisapproachandresultsarefoundin Enclosure1.2.3.1.9APLAB,CASAGrande-PlantCon"guration:Question3b STPResponse:(Item3b,Page36)2.3.1.10APLAB,CASAGrande-PlantCon"guration:Question3cSTPResponse:(Item3c,Page36)2.3.1.11APLAB,CASAGrandetoPRAInterface-General:Ques-tion2aSTPResponse:(Item2a,Page38)ThelargestbreaksizebelowwhichnofailuresrelatedtoeitherthesumporvesselperformancewererecordedduringtheCASAGranderunswasaDEGB ina5.189Dinchpipe.TheesizeoftheDEGBbreakina5.189Dinchpipeis5

.189x2 1/2=7.338inch.TheesizewasusedtoassignDEGBcasestoaLOCAcategory.Therefore,thisisthetransitionbreaksizebelowwhichnofailureswererecorded andabovewhichfailureswereobservedinsomecases.Thisspeci"cbreakwas characterizedasaLargeLOCA.2.3.1.12APLAB,CASAGrandetoPRAInterface-General:Ques-tion2bSTPResponse:(Item2b,Page38)TherearenoscenariotimingdforthedebrismodelcomparedtothebasePRA,changesinsuccesscriteriaasaresultofdebris,andchangesin operatorresponse.Figure1.3,fromLAREnc.4-3,reproducedbelow,showstherelationshipbetweentheSTPPRAmodelandCASAGrande.Withrespecttotimingand successcriteriathetwomodelsare,ofnecessity,consistent.Tuesday1 stMarch,2016:19:32,Page238of393 DRAFTPART2.RAIRESPONSES(ROUND1)Tuesday1 stMarch,2016:19:32,Page239of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.13APLAB,STPPRAModel-General:Question1STPResponse:(Item1,Page40)AnindependentfocusedpeerreviewfollowedanupgradetotheHumanReliabilityAnalysis.TheresultsofthatreviewarefoundinEnclosureA.No Signi"canceLevelA"ndingswerefound.AllLevelBobservations(Enclosure B)wereresolvedandincorporatedintothePRA.AfocusedindependentreviewoftheelectricpowerrecoveryanalysiswasperformedwiththeresolutionofthecommentssummarizedinEnclosureC.All commentshavebeenresolved.2.3.1.14APLAB,STPPRAModel-General:Question3 STPResponse:(Item3,Page40)Itwasdeterminedthattherequirementsspeci"edforinternaleventsat-powerPRAareapplicableforthisspeci"capplicationatSTP(pleasereferto theresponsetoAPLAB,STPPRAModel-RAI-2,NOC-AE-14003101,June25, 2014,ML14178A481andML14178A485).ThePRAonwhichtheGSI-191RIapplicationisbasedwasdevelopedfromtheSTPPRAmodelofrecord(MOR).TheSTPPRAMORhasbeenpeer reviewedandfoundtocomplywithcapabilitycategoryIIforallinternalevent, level1and2requirements.TheGSI-191PRArequiredfocusedmodi"cationofsixoftheeightinter-naleventtechnicalelements:InitiatingEventAnalysis(IE),AccidentSequence Analysis(AS),SuccessCriteria(SC),SystemsAnalysis(SY),andQuanti"cation (QU).TheHumanReliabilityAnalysis(HR),DataAnalysis(DA),andLERF Analysis(LE)werenotimpactedbythechangestotheMORtocreatetheGSI 191PRA.Theprocessofprovidingareasonablycompleteidenti"cationofrelevantinitiatingevents(HighLevelRequirementIE-A)isdiscussedintheenclosureto theresponsetoAPLAB,STPPRAModel-RAI-2,NOC-AE-14003101,June25, 2014,ML14178A481andML14178A485).Modi"cationstotheMORdidnotimpactthisHighLevelRequirementsothattheGSI191PRAmeetsallsupportingrequirementsderivingfromIE-A.

Likewisethegroupingoftheinitiators(thefocusofHighLevelRequirement IE-B)wasnotchangedfromtheMORsothattheGSI-191PRAmeetsall supportingrequirementsderivingfromIE-B.AsexplainedintheLAR,theGSI-191PRAdidadaptanapproachtothequanti"cationoftheLOCAfrequencies(thefocusofHighLevelRequirement IE-C)thatisdistinctfromthatadoptedintheMOR.Supportingrequirements IE-ClthroughIE-C6,IE-C12,IE-C13andIE-C15areapplicable.Timetrend analysis(IE-C7)isnotnecessarytomeetCapabilityCategoryII.Faulttree analysiswasnotused,soIE-C8throughIE-C11arenotapplicable.Supporting RequirementsIE-D1throughIE-D3(pertainingtoDocumentation)areapplica-

ble.Modi"cationstotheAccidentSequencemodelweremadetoexplicitlyin-cludetheimpactofGSI-191issues.SupportingrequirementsAS-Althrough AS-All,AS-B1throughAS-B7,andAS-ClthroughAS-C3areapplicable.HighLevelRequirementSC-Aspeci"estherequirementsforsuccesscriteria.Tuesday1 stMarch,2016:19:32,Page240of393 DRAFTPART2.RAIRESPONSES(ROUND1)SupportingrequirementSC-A2isapplicableasitprovidesguidanceforaccep-tancerequirements.SXC-A5(pertainingtomissiontime)andSC-A6(consis-tencywithfeatures,proceduresandoperatingphilosophy)areapplicable.The de"nitionofcoredamage(SC-Al),thesuccesscriteriaforkeysafetyfunctions (SC-A2)arenotmodi"edfromtheMORandthereforeremainCapabilityCate-goryIIandnotapplicableinthereviewoftheGSI191PRA.TheMediumand LargeLOCAaccidentsequencemodelsdonotcreditsystemssharedbetween thetwounits,soSC-A4isnotapplicable.SC-B1throughSC-B5(whichpertaintothermal-hydraulicandothersup-portinganalyses)areapplicable.SC-ClthroughSC-C3(pertainingtodocumen-tation)areapplicable.ThechangestotheSystemsModelsprimarilyinvolvedprovidinglogictoincorporatetheresultsofthesupportingphenomenologicalanalyses(e.g.,results fromCASAGrande).ApplicableSupportingRequirementsassociatedwithHigh LevelRequirementSY-A(whichseeksareasonablycompletetreatmentofcauses forunavailability)arelimitedtoSY-AlthroughSY-A7,SY-A9throughSY-A14,andSY-A21throughSY-A24.SY-A8referstoestablishingcomponent boundariesandisnotapplicable.SY-Al5throughSY-A20areotherwisenot applicable.SY-A15pertainstotruncatingthesystemmodel,whichwasnot doneinthesystemmodel.SY-A16andSY-A17pertaintohumanfactorswhich arenotincludedinthephenomenologicalmodels.SY-A18throughSY-A20are otherwisenotrelevant.HighLevelRequirementSY-Bfocusesonthereasonablycompletetreatmentofcommoncausefailures,intersystemandintersystemdependencies.Because thesystemsanalysesarebeingusedtointroduceeventsofaphenomenological nature,onlySY-B6whichaddressespotentialspatialorenvironmentalimpacts isapplicable.SupportingrequirementsSY-ClthroughSY-C3pertaintodocu-mentationandareapplicable.MostsupportingrequirementsassociatedwiththeQUHighLevelRequire-mentsareapplicable.TheoneexceptionisQU-D4which,forcapabilitycategory II,callsforthecomparisontotheresultsfromsimilarplants.AsSTPisapilot plant,thisisnotpracticable.TheapplicablesupportingrequirementsremainmetatcapabilitycategoryII.Therealisticplant-speci"cthermal-hydraulicsandothersupportinganalysis arelikelycapabilitycategoryIll.Theseclaimsarenottheresultofaconven-tionalpeerreview,butrathertheconclusionsofanin-depthindependentreview.Thisreviewwasconductedbyanindependenttechnicaloversightteamfromthe UniversityofIllinoisUrbana-Champaign.2.3.1.15APLAB,STPPRAModel-SuccessCriteria:Question1 STPResponse:(Item1,Page41)Section15.6.5.4.3oftheSTPUFSARnotesthatminimumsafetyinjectioncapacityisadequateforallbreaksbetween2-10inches;i.e.,1trainfailsand2 trainsstart,oneofwhichgoesoutthebreak.The2inchbreaksizeislimiting forPCT.Theanalysisperformedtojustifythisconclusionwasperformedinthe absenceofconsideringGSI-191phenomena.AnalysesperformedinsupportoftheLARincludedconsiderationofa6inchhotlegbreakwithonlyonetrainofECCSavailable.NotethatincasesinwhichTuesday1 stMarch,2016:19:32,Page241of393 DRAFTPART2.RAIRESPONSES(ROUND1)onlyasingletrainofECCSisavailable,switchovertohotleginjectionisnotperformed.TheevaluationincludedconsiderationofdebrisTheanalyses indicatethatthecoreisre"ooded,evenifdebrisblockstheinlettothefuel channels.ItisconcludedthatGSI-191phenomenadonotimpactthesuccesscriteriausedinthePRA.2.3.1.16APLAB,STPPRAModel-SuccessCriteria:Question2a STPResponse:(Item2a,Page41)ThebreaksizesandlocationsassumedintheRELAP5simulationswereconsistentwiththoseusedinthePRAandelsewhereinCASAGrande.2.3.1.17APLAB,STPPRAModel-SuccessCriteria:Question2b STPResponse:(Item2b,Page41)ThesuccesscriteriausedinthePRAformediumLOCAarebasedonanal-ysesre"ectedintheFSAR,namelythatatleastonetrainofECCSisavailable.

TheanalysesperformedforthecasewherealltrainsofECCSareavailable indicatethatboronprecipitationwillnotoccurformediumhotlegbreaks.ThesupportingthermalhydraulicanalysesperformedinsupportoftheLARalsoincludedconsiderationofa6inchbreakinthehotlegwithonlyonetrainof ECCSavailable.Theassumedbreakrepresentsthelimitingcaseforamedium hotlegLOCA,andtheconditionofasingletrainofECCSavailablerepresents pumpstate43.TheresultsoftheRELAP5analysisshowthatthecoreremains adequatelycooled.Inaddition,theliquidlevelinthecoreisquicklyrecovered, soboronprecipitationisnotcredibleinmediumLOCAscenarioswithlessthan threeECCStrainsavailable(assumingHLSOissuccessful).2.3.1.18APLAB,STPPRAModel-SuccessCriteria:Question2c STPResponse:(Item2c,Page41)LOCADMisacalculationtoolthatcanbeusedtoconservativelypredictthebuild-upofchemicalsdepositsonfuelcladdingafteraLOCAandtheon thecladdingtemperatureduetothechange(degradation)oftheoverallcladding conductivity.RELAP5-3Ddoesnothavethecapabilitytopredictthebuild-upofchemicalsdepositsonthefuelbutitiscapabletopredicttheeoftheconductivity degradationonthesurfacecladdingtemperature,giventhatthethicknessof thedepositanditsthermalconductivityisspeci"edasaninputparameterin thecoreheatstructure.AtthetimetheRELAP5-3Dmodelwasdevelopedand thethermal-hydrauliccalculations(speci"callythecoreblockageanalysis)were performed,thedepositionlayerwasnotincludedintheinputmodelofthecore heatstructure.Nevertheless,ifthefollowingcharacteristicsofthedepositlayer areassumed:

• Thickness=13.64mils(346.456lLm)(LAR:Volume3Paragraph5.10.1)

• ThermalConductivity=0.1Btu/(Ffth)(WCAP-16793-NP)theincreaseinisapproximately40F.TheconclusionisreachedthattheeofthedepositionlayeronthecladdingtemperaturedoesnotchangeTuesday1 stMarch,2016:19:32,Page242of393 DRAFTPART2.RAIRESPONSES(ROUND1)theoutcomeofthesimulationresultsperformedwiththeRELAP5-3Dmodelsforthecoreblockagescenarios.2.3.1.19APLAB,STPPRAModel-SuccessCriteria:Question3a STPResponse:(Item3a,Page42)CASAGrandeanalysesfortheSTPLARuseda36-hrperiodtoevaluatefailuremodesarisingfromdebrisaccumulationonthestrainerandonthecore.CASAGrandecomputestheparametersthatchangesigni"cantlyand/orhavepotentialimpactonpost-LOCAoperationwithinthe30daymissiontime.

However,STPparametricstudiesshowthatphenomenathatoccurwithinthe "rst18hoursessentiallyde"nethesuccessorfailureofpost-LOCAECCSop-eration.ECCSfailureprobabilitydoesnotincreasesigni"cantlyafter18hours.A36hours(2times18)analysistimewaschosenasareasonableanalysisperiodtoensurethetailendprobabilitiesareconsideredandtokeepCASArun timesalsowithinareasonableduration.Additionally,theconditionsandmechanismsassociatedwithdebrisareestablishedwithinthe"rst18-36hoursfromthestartoftheLOCA.There-foreatimerangeof36hoursprovidesthekeyparametersandbasisforconclud-ingECCSpost-LOCAsuccessorfailureandthereforeelyaddressesa30 daymissiontime.OtheranalysesperformedoutsideofCASAGrandeandtheir assumedaccidentdurationsareasfollows:Unquali"edCoatingsFailureTransport.Containmenttransportoffailedunquali"edcoatingsisconservativelymod-eledasbeingintroducedataconstantratefrom0to10minutes.Essentiallyall debrisisaccumulatedonthestrainerwithinafewpoolturn-overperiods.Hence by36hours,allofthecontributionfromthisparameterisconsidered.Notethat theactualtimerangeofUnquali"edCoatingsFailureandtransportis0min 30days.(SeeVolume3,Table5.5.5)DebrisTransport.100%ofdebristransportstotheactivesumpstrainersisconsideredtobecompletedwithin10hours,asveri"edbytrackingaccumulatedinventoryasa functionoftime.FormationofChemicalPrecipitants.Formationofchemicalprecipitantsisconsideredtooccurwithin10to20hoursfromthestartoftheaccident,baseduponthetemperaturepro"lesused andtheassumptionofaforcedprecipitationtemperature.(SeeVolume3,Figure

2.2.1)ChemicalStrainerheadloss,includingchemicalisassumedtoapproachanasymptoticvalueatapproximately2,000minutes,i.e.,33.3hours,afterthe LOCA.(SeeVolume3,Figure5.6.6)OperatorActions.OperatoractionssuchassecuringpumpsorswitchingovertohotleginjectionaremodeledconsistentwithEOPsandSAMGsConsequently,theeaccidentdurationusedbyCASAGrandetocal-culatetheconditionalprobabilityofsumpandcoreblockageis30days.Tuesday1 stMarch,2016:19:32,Page243of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.20APLAB,STPPRAModel-SuccessCriteria:Question3bSTPResponse:(Item3b,Page42)SensitivitystudieswereperformedontheCASAGrandeanalysisduration.Decreasingthesimulationtimefrom36hoursto24hourshadonlyanincidental onindicatingthatsuccessscenarioshadreachedasafe,stable endstate.Thefulleofchemicalprecipitateswasincludedforanyscenario meetingthebed-thicknessandprecipitationcriteriawithinthedurationofthe simulation,soinelong-termchemicalwereforcedtooccurwithin thetime-frameofinterestregardlessoftheactualtimeneededforcorrosionand precipitationphenomenatodevelopunderrealisticconditions.2.3.1.21APLAB,STPPRAModel-SuccessCriteria:Question3cSTPResponse:(Item3c,Page42)Thesafe,stableendstatecanbeunderstoodbyreferringtothemediumandlargeLOCAeventsequencediagrampresentedinVolume2,AppendixA, FigureA.3-1.Onlyonestableconditionisshown,andthatisontherightside ofsheet2ofthe"gure.Thestableconditionresultsifcoredamageisavoided.

Downbranchesinthe"gureindicatefailuresthatmayormaynotleadtocore damageendstatesdependingonsubsequentevents.Thecoredamageendstates areshownasredsymbols.Toreachtheone,safestableendstateinresponsetoamediumorlargeLOCArequires:

• Successfulreactortrip,*Successfulsafetyinjectionactuation,*MSIVclosureorturbinetriporthereactorwithstandingapotentialPTSovercoolingchallenge,*taccumulatorinjection,*LowheadpumpinjectiontotheRCS

• Highheadpumpinjection(notrequiredifalargeLOCA)

• Lowheadpumpsinsumprecirculationmode

• SumpavailableforrecirculationconsideringGSI-191issues

• Noin-vessel"owblockage

• Noboronprecipitationleadingtolossofcorecooling,and

• DecayheatremovalbyeithertheRHRheatexchangersorthecontainmentfancoolersIfthebreakisinthecoldleg,thensuccessfulhotlegswitchoverisalsorequiredinordertoavoidexcessiveboronprecipitation.Attheendofasafe, stablesequence,oneormorelowheadpumpsarealignedforsumprecirculation, atleastonetraintoanRCSloopviathecoldleg,and0,1,or2thehotlegsofthe remainingloops.AtleastonelowheadpumpmustbealignedtoanRCSloopTuesday1 stMarch,2016:19:32,Page244of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatremainsintact;i.e.toanRCSloopthatisnotwherethebreakislocated.Themostlikelysafe,stableendstateisthatallcontainmentfancoolersare operatingandthatcoolingtothesecondarysideofeachRHRheatexchanger alignedforlowheadpumpsumprecirculationisavailable.Thesearetheonly safe,stableendstatescreditedintheSTPPRAformediumandlargeLOCAs.2.3.1.22APLAB,STPPRAModel-SuccessCriteria:Question3d STPResponse:(Item3d,Page42)NochangesweremadetotheoutputsfromCASAGrandetoadjustforthePRAmissiontime.Theywerejudgedsuitableandusedasis.2.3.1.23APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3aSTPResponse:(Item3a,Page43)CASAGrandesamplesthepost-LOCAtimeatwhichonetrainofcontain-mentsprayissecuredfromdistributionsde"nedbytheuserforsmall,medium andlargebreaks.FortheSTPLAR,thesetimeswerede"nedasnormaldistri-butionswiththefollowingmeanandstandarddeviation:0

+/-0min.forSBLOCA(spraysneveron),20

+/-5min.forMBLOCA,and20

+/-5min.forLBLOCA.Sump"owratesandsump"owratedependentphysicalphenomenaaretheonlyplant conditionsthatthetimetosecureonesprayinputinthesimulation.

RWSTdraindowntimesareassignedpointvaluesforvaryingbreaksizes,calcu-latedwithtwocontainmentspraypumpsrunningbecausethesevaluesresultin themostprobablerecirculationswitchovertimes(LAREncl.4-3,Pg.33).Failed debriswashdownratesareassignedpointvaluestakenfromdeterministicanal-ysiswheretwocontainmentspraypumpswereassumedoperational(LAREncl.

4-3,Ref.23).DescriptionsofotherinputsandtheirassignmentinCASAGrande arelistedintheresponsetoAPLAB,CASAGrande-GeneralRAI1.Itisnotedthatstatisticalsamplingdoesnotprecludeselectionofaverylongtaskperformancetimethatelyrepresentsfailureofmanualactions.

However,nostrategiesareemployedtoensurethatthisconditionisalways representedinthestatisticaldesign.2.3.1.24APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3bSTPResponse:(Item3b,Page43)No,CASAGrandedoesnotmodeltheplantconditionsthatwouldoccuriftheoperatorsfailtosecurecontainmentspraylongtermoncecontainment pressureandiodinelevelsaresuitablylowi.e.,themanualactionsassociated withOFFSareunsuccessful.Speci"cally,CASAGrandesamplesthepost-LOCAtimeatwhichalltrainsofcontainmentsprayaresecuredfromdistributionsde"nedbytheuserfor small,mediumandlargebreaks.FortheSTPLAR,thesearede"nedasnormal distributionswiththefollowingmean,standarddeviationandtruncationlimits:

390+/-5min.between390and420min.forSBLOCA,390

+/-10min.between390and420min.forMBLOCA,and390

+/-15min.between390and450min.forLBLOCA.Forthesecases,thetruncationlimitsprecludeperformancetimes beyond450min.(7.5hr).Plantconditions(ie.sump"owrates,washdownrates,Tuesday1 stMarch,2016:19:32,Page245of393 DRAFTPART2.RAIRESPONSES(ROUND1)RWSTdrain-downtimes,etc.)arenotmodeledfortheconditionwhereoperatorsfailtosecurelong-termcontainmentspray.2.3.1.25APLAB,STPPRAModel-HumanReliabilityAnalysis:Ques-tion3cSTPResponse:(Item3c,Page43)ThePRAmodeldoesincludelogictorepresentfailuretotriponerunningcontainmentspraypumpaswellasfailuretotripallcontainmentspraypumps lateinthesequence.However,therearenoresultsfromCASAGrandethatare representativeofthesefailureconditions.Failuretotriponerunningcontainment spraypumpearlyinthesequencewouldresultinthedebrisbeingapproximately evenlydividedamongthethreesumpstrainerswithacorrespondinglowerhead lossthaninthecaseofonlytworunningcontainmentspraypumps.Sincefailure ofonestrainerisassumedtoresultinfailureofallstrainers,thisapproach isconservativeforstrainerheadloss.However,theapproachmaybeslightly unconservativewithrespecttoin-vesseleastheadditionaldebrisonthe strainerwouldprovidemore"ltration.2.3.1.26APLAB,STPPRAModel-PRAScope:Question2 STPResponse:(Item2,Page45)IntheresponsetoAPLAB,STPPRAModel-PRAScope:RAI1(STPletterprovidedtoNRCSNOC-AE-14003103,May22,2014,ML14149A434 page24),itwasestablishedthatthemeanfrequencyofaseismicallyinduced MediumLOCAisestimatedtobe1.08x10-7peryear.Theboundingassumption ofaconditionallikelihoodof0.1forrecirculationfailurefollowingaseismicevent suggeststhecontributiontomeancoredamagefrequencyduetoaseismically inducedMediumLOCAisnogreaterthan1

.1x108peryear.2.3.1.27APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1aSTPResponse:(Item1a,Page46)Keysourcesofmodeluncertaintyare:

• Successcriteriaforfuelblockageandboronprecipitation

• Fiberpenetrationofthesumpstrainer

• Headlosscorrelationatsumpstrainer

• Debrisgeneration,includingsizeandshapeofzoneofin"uence

• Debristransporttothesump

• Abilityofchemicalprecipitatestocauseincreasedstrainerheadlossandfuelblockage2.3.1.28APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1bSTPResponse:(Item1b,Page46)Keyassumptionsmadeare:Tuesday1 stMarch,2016:19:32,Page246of393 DRAFTPART2.RAIRESPONSES(ROUND1)

• Adiscretesetofoperabilitystatesofthepumpstakingsuctionfromthecontainmentsumpwasadopted.Inagivenscenario,thespeci"ccon"gu-rationofoperatingpumpswasboundedbyaonememberofasetof"ve analyzedcases.Ifaspeci"cpumpcon"gurationwasnotboundedbyone ofthe"veanalyzedcases,coredamagewasassumedtooccur.

• Failureconditionsfoundatoneormoreofthethreecontainmentsumpswasassumedtoresultinfailureatallthreesumps.

• Forcoldlegbreaks,itwasassumedthatboronprecipitationwouldbepossiblewithouthotleginjectionswitchover.

• Alargezoneofin"uenceforjetinduceddebrisgenerationwasassumed.

• Whenincreasedbyafactorof5,theNUREG/CR-6224isexpectedtoboundconventionalheadloss.

• Itwasassumedthatnocorebypasscapabilityisavailableforblockageexceeding7.5gperfuelassembly.

• Nocredittakenforcorebypass.2.3.1.29APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion1cSTPResponse:(Item1c,Page46)Theadaptationofdiscretepumpoperabilitystateslikelyhadamodestcon-servativeimpactontheresultsforLargeLOCA.However,thisassumptionhad amoresigni"cantconservativeimpactintheassessmentofMediumLOCAs.

100%ofthereportedcontributionofsumpfailureforMediumLOCAswasdue tosequenceswithpumpoperabilitycombinationsthatwerenotboundedby the"veanalyzedpumpstates.Ifa"nermoredetailedsetofpumpstateswere chosen,thenthecalculateddeltaCDFwouldbelower.Theassumptionthatfailureconditionsatonesumpwouldresultinfailureatallsumpsisconservative.Theheadlosscorrelationused,includingbumpupfactors,isconservativebasedontheresultsoftheSTP-speci"cheadlosstests.TheassumptionthatboronprecipitationfollowingMediumcoldlegbreaksislikelyconservative.Thelargezoneofin"uencefordebrisgenerationisboundingandpossiblyconservative.TheassumptionthatbreaksoccuronalegequippedwithSIyieldsaslightlyconservativeresult,asthereisonlya1/4likelihoodthatthebreakwouldbeon thelegwithoutSI.PleaseseetheresponsetoAPLAB,ResultsInterpretation-UncertaintyAnal-ysis:RAI6foradditionaldescriptionofthesensitivityanalysesconducted.2.3.1.30APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion3STPResponse:(Item3,Page47)AsdescribedintheLAREnclosure4-1,Section2.1.2,allSTPlarge-borepipingPWSCC-susceptiblewelds(nozzlewelds)havebeenreplacedorother-wisemitigated,withtheexceptionofthereactorvesselnozzlewelds.AsfurtherTuesday1 stMarch,2016:19:32,Page247of393 DRAFTPART2.RAIRESPONSES(ROUND1)described,thereactorvesselnozzleweldsarelessofaconcernintheGSI-191analysisthanareotherbreaklocationsbecausethereactorvesseliscovered withRMI,andtheprimaryshieldwallwouldprotectthemajorityof"berglass insulationinthesteamgeneratorcompartments.Finally,STPNOCiscurrently incompliancewithASMESectionXIweldinspections.BothSTPplantsareatapproximately25yearsofserviceandthereforeitisappropriatetoexpectthatthe25-yearLOCAfrequencyvalueswouldapply.It isfurtherreasonableto"reset"theeetimeofservicetomuchlessthan25 yearswhentakingintoaccountthemostproblematicweldshavebeenmitigated orreplaced.The40yearestimatesforCDF,LERF,andareprovidedinEnclosure5.Thefollowingtablesummarizesthe40yearestimates.Table2: defaultParameterValueCDF2.20E-05LERF1.38E-06 6.85E-08 1.12E-102.3.1.31APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4aSTPResponse:(Item4a,Page47)QuantileswereelicitedinNUREG-1829atthe5th,50th,and95th.Themeanvalueswerenotelicitedbutinstead,werederivedfromasplitlognormal distributionfortheelicitedquantiles.ThedistributionsusedintheLARwere developedtomostclosely"tthevalueselicitedintheexpertelicitationprocess.

AsdescribedinEnclosure6,becausethemeanvaluesareusedbythePRA fortheinitiatingeventfrequencies,andLERFactuallyusethemean valuesfromNUREG-1829.2.3.1.32APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4bSTPResponse:(Item4b,Page47)ThealgorithmusedtosolvethatmodeltakesasinputinitialvaluesfortheJohnsonparametersasastartingpointfortheoptimizationalgorithm.For eachcategory,thevalueofthelowerbound,,oftheJohnsondistributionwasinitializedtohalfofthe5thpercentilegiveninNUREG-1829,andtherange,,wasinitializedtotwicethe95thpercentile.Thiswasdonetoproduceadditional spreadofthedistributionoutsidetheNUREG-1829percentilesandthereby capturingareasonablerangeofuncertainty.AlternativeJohnsondistributions couldbeobtainedbyrangingtheJohnsonscaleparameter,,that"tthethreepercentileselicitedfromexpertsaspartofNUREG-1829asshowninEnclosure7.

AlthoughJohnson"tscanbeobtainedwithhighermeanfrequencies,increasing thescalefactortoafactorof100timesthe95thpercentileofthefrequencies elicitedfromexpertsinNUREG-1829produceslessthana2%increaseinTuesday1 stMarch,2016:19:32,Page248of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.1.33APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4cSTPResponse:(Item4c,Page48)AsshowninEnclosure8changesinCDF,LERF,andaremodestwhentheJohnsonscaleparameter,,israngedfromafactorof1.25uptoafactorof100timesthe95thpercentileofthefrequencieselicitedfrom expertsinNUREG-1829.(Afactorofabout2.00wasusedinSTPssubmittal.)

Morespeci"cally,pointestimatesofandincreasebynomore than2%forthespeci"cvaluesofconsideredinEnclosure8.EstimatesofCDFandLERFdfromandLERFbyvaluesthatdonotdependon.2.3.1.34APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion4dSTPResponse:(Item4d,Page48)Thedistributionsderivedfromthe"ttedboundedJohnsondistributionswerescaledforuseinthePRA.Thiswasdonetomatchtheresultingmeanvalues withthemeansinterpolateddirectlyfromNUREG-1829.2.3.1.35APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion5STPResponse:(Item5,Page48)TheCASAGrandeevaluationofGSI-191failurephenomenaispartlyde-pendentontheLOCAfrequencyuncertainties,butnotontheabsoluteLOCA Frequencyestimates.Theallocationofbreaksizes,withinCASAGrande,is dependentonthedownwardslopeoftheLOCAexceedancefrequencieswithin thebreaksizerangebeinginvestigated.Thechangeinslopewithinthesmall, medium,orlargeLOCAbreaksizesdictatestheweightsgiventothedt breaksizesonlywithinthesizebeinginvestigated.Thebreakfrequenciesat everybreaksizecouldbemultipliedbyafactor,andtheestimatesfromCASA Grandewouldnotchange,becausetherelativeallocationofbreakfrequency toeachsub-intervalwithin,saytheLargeLOCA,breaksizerangewouldnot change.ForthePRA,thecoredamagefrequencydependenceisontheinfrequencyattwopointsontheLOCAfrequencyexceedancecurve.Multiplying theLOCAfrequencyatthetwopointsbyafactorwouldchangethebreak intervalfrequencybythatsamefactor.Thereisnodependenceonthevarying slopewithinthetwobreaksizes,onlytheontheoverallfrequencydBoththePRAandCASAGrandeusethesamebreaksizeintervalsandthisisaccountedforinboth.WebelievethisdependenceofthePRAandCASA GrandeontparametersoftheLOCAbreakfrequenciesistso astonotwarrantcorrelationbetweenthePRAandCASAGrande.2.3.1.36APLAB,ResultsInterpretation-UncertaintyAnalysis:Ques-tion6STPResponse:(Item6,Page48)Asensitivityanalysiswasperformedby1)developingthescopeofpoten-tiallyimportantcontributorstoandthen2)analyzingtheirindividual contributionsinaone-waysensitivitystudy.ThestudywasthenexpandedtoTuesday1 stMarch,2016:19:32,Page249of393 DRAFTPART2.RAIRESPONSES(ROUND1)includeaggregatecontributionsfromthetwohighestcontributors,"berpen-etrationthroughtheemergencycorecoolingsystemstrainersandthesuccess criteriaforboronprecipitation(boron"berlimit).Therestofthecontributions werejudgedtobelessimportantintheaggregatebasedontheone-wayanalysis.

TheCDFestimateismostsensitivetothreeparametersthatconcern:1)how muchdebrisisrequiredtotriggeranin-vesselfailure(boron"berlimit),2)the fractionofdebristhatpenetratesthesumpstrainer("berpenetrationfunction),

and3)thefractionofdebrisofttypesthatistransportedfrom entlocationsduringdtoperationalphases(debristransportfractionsin ZOI).Theeoftheboron"berlimitexceedsthatofthenextmostsensitive parameterbyanorderofmagnitude.Ananalysisofthesensitivitytotheaggre-gateofthebypassfractionandboron"berlimitisshowninthefollowing

"gure.Tuesday1 stMarch,2016:19:32,Page250of393 DRAFTPART2.RAIRESPONSES(ROUND1)EnclosurestoAttachment1APLAB,CASAGrande-PlantCon"guration:RAI3Enclosure1-ResponsetoAPLAB,CASAGrandePlantCon"guration:RAI3PlantCon"guration:

CombinationsofPumpFailuresAPLAB,STPPRAModel-GeneralRAI-1Enclosure2(A)-AttachmentAtoCR07-1684ResolutionofPRAHRAUpdateReportPeerReviewFact/Ob-servation(F&O)Comments Enclosure3(B)-LevelBobservationsresolved Enclosure4(C)-IndependentReviewoftheElectricPowerRecoveryAnalysisAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI3Enclosure5-ResponsetoAPLAB25vs40YearFrequencyEstimates:RAI3APLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4aEnclosure6-ExplanationoftheDiscrepancyinMeanLOCAFrequenciesforFittedJohnson DistributionversusNUREG-1829ValuesAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4bEnclosure7-ExplanationoftheJohnsonDistributionGoverningLOCAFrequencyand SensitivityofSummaryStatisticstoScaleParametersAPLAB,ResultsInterpretation-UncertaintyAnalysis:RAI4cEnclosure8-ExplanationoftheImpactofJohnsonDistributionSelectiononCDF,LERF, LERF2.3.2ACRBResponses 2.3.2.1ARCB:Question1 STPResponse:(Item1,Page49)TheresponsetoARCB,RAI1wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.2.2ARCB:Question2 STPResponse:(Item2,Page49)TheresponsetoARCB,RAI2wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.2.3ARCB:Question3 STPResponse:(Item3,Page50)TheresponsetoARCB,RAI3wasprovidedintheSTPlettertoNRCdatedMarch17,2014NOC-AE-14003082,ML14086A385,ML14086A386, ML14086A387.2.3.3EMCBResponses 2.3.3.1ECMB,Question1 STPResponse:(Item1,Page50)TheresponsetoEMCBRAI1wasprovidedintheSTPlettertoNRCdatedDecember23,2013,NOC-AE-13003065,ML14015A311.Tuesday1 stMarch,2016:19:32,Page251of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.3.2EMCB,Question2STPResponse:(Item2,Page51)ResponsetoEMCBFollow-upRAIdatedJune2,2014ThetwocasestabulatedinNOC-AE-13003065asCases1and2usedtialpressuresof2.47psiand4.00psi,respectively.CaseIisforthehigh temperaturecaseof2670F.Case2isforthelowtemperaturecaseof1280F.ThestrainerloadusedforCase1is5.71ftwhichisequivalentto2.47psiusingadensityvalueof62.4lbpercubicfeet(coldwaterdensitywasconserva-tivelyused).ThestrainerloadusedforCase2is9.35ftwhichisequivalentto 4.0psiusingadensityof61.58lbpercubicfeet.Deterministicanalysisshowedthatthestrainersdonotfailunderanydesignbasisloadingcondition.ThoseresultswereprovidedinthetabulatedIRvalues previouslysubmitted.Asnotedinthequestion,allIRvalueswerelessthan one.UnlikeDeterministicanalysis,Probabilisticanalysisconsidersfailuretobe alwayspossibleandattemptstoquantifytheprobability.FortheProbabilistic analysis,"failure"isde"nedtobeanyscenariowitharesultingdtialpres-suregreaterthan9.35ft(thehighestanalyzedinthestructuralquali"cation calculationwhichusesCodeallowables).SinceCodeallowablesincludeconsid-erablemargintoactualphysicalfailure,thisde"nitionoffailureisconservative.TheproposedchangetotheUFSARis:

6.2.2.2.3ContainmentEmergencySumpDescriptionAtthebeginningoftherecirculationphase,theminimumwaterlevelabovetheContainment"oorisadequatetoprovidetherequiredNPSHfortheECCS andCSSpumps.ThesumpsaredesignedtoRG1.82,proposedRevision1,May 1983andwithconsiderationofthedebrisidenti"edinGenericLetter 2004-02,asdescribedinAppendix6A.Thesumpstructuresaredesignedto limitapproach"owvelocitiestolessthan0.009ft/secpermittinghigh-density particlestosettleoutonthe"oorandminimizethepossibilityofcloggingthe strainers.Thesumpstructuresaredesignedtowithstandthemaximumexpected tialpressureimposedbytheaccumulationofdebris.Therisk-informedmethodologyappliedtoevaluatetheriskassociatedwithctsofdebrisshows thattheincreaseinriskassociatedwithdebristhatwouldexceedthedesignlimitsofthesumpstructuresisverysmall,inaccordancewiththeacceptancecriteria ofRegulatoryGuide1.174.2.3.4ENPBResponses2.3.4.1ENPB,Question1 STPResponse:(Item1,Page51)AsdescribedinseveralplacesintheLAR(forexample,Enclosure4-1,Sec-tion2.3.5,Enclosure42,Section2,andEnclosure4-3,Section5.3)theEPRI RI-ISIfrequenciesarenotusedtodirectlydevelopLOCAfrequencies.NUREG 1829(Enclosure4-3,Reference[37]),frequenciesareusedasthebasisforLOCA frequenciesandtheEPRIRI-ISIfrequenciesareonlyusedasweightstodis-tributetheNUREG1829frequenciesmoreheavilytolocationswheredegrada-tionmechanisms(DMs)areknowntobepresent.Thefollowingsummarizesthe processusedtoidentifytheDMsusedintheLAR.TheassessmentofDMsusceptibilityisperformedinthreesteps:1.IndependentreviewofthedegradationmechanismevaluationperformedTuesday1 stMarch,2016:19:32,Page252of393 DRAFTPART2.RAIRESPONSES(ROUND1)fortheSTPRI-ISIProgram[1,2,3,4]2.SystematicreviewofthecurrentworldwideserviceexperiencewithCodeClass1pipinginWestinghousePWRplants,and3.ReviewofrelevantindustryreportsonmaterialdegradationDMsusceptibilityscreeningcriteriaareappliedtodetermineapplicableDM-susceptiblelocationsasreferencedinEPRITR-112657.OnlythoseDMsthat applytotheenvironmental,stress/loadconditions,andmaterialtypesthatare foundintheSTPreactorcoolantpressureboundarypipingareincluded.

References:

1.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlternativetotheASMEBoilerandPressureVesselCodeSectionXIExamina-tionRequirementsforClass1PipingWelds,RR-ENG-2-16,December1999.

2.StructuralIntegrityAssociates,Inc.,DegradationMechanismEvaluationfor theSouthTexasProjectElectricGeneratingStation(STPEGS)Units1and2, EPRI-116-330,Rev.0,December1999.

3.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlter-nativetotheASMEBoilerandPressureVesselCodeSectionXIRequirements forClass1SocketWeldedPipingandClass2PipingWelds,RR-ENG-2-23, February2001.

4.STPNuclearOperatingCompany,ReliefRequestforApplicationofanAlter-nativetotheASMEBoilerandPressureVesselCodeSectionXIRequirements forClass1andClass2PipingWelds,RR-ENG-3-04,September2011.2.3.4.2ENPB,Question2 STPResponse:(Item2,Page51)Theinitiatingfrequenciesforthe1.5-inchand2-inchpipesizesforCategory6AwereduplicatedintheCASAGrandeanalysis.Theinitiatingfrequenciesforthe0.75-inchand1-inchpipesizesforCategory6BwereduplicatedintheCASAGrandeanalysis.Theinitiatingfrequenciesforthe1.5-inchand2-inchpipesizesforCategory8CwereduplicatedintheCASAGrandeanalysis.ThefrequenciesinSection2.2.3areusedinconjunctionwiththeweldcountsinSection5.3.1.2.3.4.3ENPB,Question3 STPResponse:(Item3,Page51)TheLOCAfrequenciesassociatedwiththeweldsintheLARanalysisarenotspeci"callyadjustedfor"awsfromtheSTPISIprogram.LOCAfrequencies areusedintwowaysintheanalysis:1)toforminitiatingeventfrequenciesin thePRAand2)toconstructajointprobabilitydistributiongoverningbreaksize andweldinCASAGrande,conditionalonaLOCAevent.For1),noadjustment ismaderelevantto"awsormitigation;thosefrequenciesaretakenfromNUREG 1829directly.Inthecaseof2),withinabreak-sizecategorythelikelihoodfor abreakataparticularweldisweightedtotakeintoaccountdegradationor mitigation,buttheprobabilityofhavingabreakineachcategorymatchesthe correspondingNUREG1829frequency.Tuesday1 stMarch,2016:19:32,Page253of393 DRAFTPART2.RAIRESPONSES(ROUND1)Therefore,NUREG1829frequenciesarepreservedintheevaluationforanygivenbreaksizeinaweightingscheme.ThemethodreferredtoastheLOCA-Hybridmethod(seetheLOCA-HybridFinalreport,ML12145A466,2012)as summarizedintheLAR(forexample,Enclosure4-1,Section2.3.5,Enclosure 4-2,Section2,Enclosure4-3,Section5.3)weightsthefrequencymoreheavily onweldswithhigherpotentialfor"aws.Theweightsarederivedbasedonan industry-widedatabaseofin-serviceinspectiondataforweldtypes,andlarger weightsaregiventotheproblematicweldtypesrelativetothosewithfewer"aws

detected.Weldsthathavebeenmitigated(replacedwithrobustweldmaterial,forexampleAlloy690,ormitigatedwithweldoverlay)areweighted(again,based onindustry-widedata)lessheavilyintheLOCA-Hybridmethod.Bothtypes oftheseweldsareinserviceatSTP,howeveronlytheweldsthatwereoverlaid onthepressurizersafeendshavebeenweightedaccordinglyintheanalysis toaccountfortheweldoverlays.Morede"nitiveexplanationofthedetailed implementationoftheLOCA-Hybridmethodhasbeenprovidedintheresponse toAPLABCASAGrande-LOCAFrequencies:RAI4,STPlettertotheNRC datedMay22,2014,ML14149A434.2.3.4.4ENPB,Question4STPResponse:(Item4,Page52)TheSTPapproachtoestimatingLOCAfrequencieswouldnotchangeasaresultofSectionXIinspection.LOCAfrequenciesaredeterminedusingthe methodologydescribedintheLOCA-HybridapproachintheresponsetoAPLAB, CASAGrandeLOCAFrequencies:RAI1providedintheSTPlettertotheNRC datedMay22,2014,ML14149A434.2.3.4.5ENPB,Question5STPResponse:(Item5,Page52)a)TheentriesinTable2.2.3de"nethedistributionofannualfrequencyoverbreaksizeforeachweldcase.The12breaksizesidenti"edinLAREnclo-sure4-3,Table2.2.3arenotusedforthesamepurposeasthe13break sizerangesplottedinFigure5.3.4.Therefore,theycannotbecompared directly.The12breaksizeswiththeirrespectivefrequencieslistedinTable2.2.3areembeddedinthecomplementaryannualfrequencydistribution(blue curve)ofFigure5.3.4.TheverticaldashedandsolidlinesinFigure5.3.4 displaythe13samplingbinsfromwhichrandombreaksizesarechosen forCase1B.Thenumberofsamplingbinsdistributedineachbreaksize categoryiscalculatedwithEquation25and26(LAREnclosure4-3,Page 150).Acompleteexplanationforhow13samplingbinsareidenti"edfor Case1BisprovidedinSection5.3.5ofLAREnclosure4-3.Horizontallinesillustratetheannualfrequencyweightscarriedbyeachbreaksizerange.Theweightforeachbreakscenariois calculatedastheoftheupperandlowercomplemen-taryannualfrequenciesthatcorrespondtotheboundsofeach samplingbin(positivedofthehorizontallines).Tuesday1 stMarch,2016:19:32,Page254of393 DRAFTPART2.RAIRESPONSES(ROUND1)b)Therearemanypossiblescenariosforselectingasetofbreaksizesateachweld.ThescenarioillustratedinFigure5.3.4(Volume3,Rev.2,Pg.151) isbuiltonthecomplementaryannualfrequenciesofTable2.2.3(Volume3, Rev.2,Pg.35)andrepresentsanonuniformstrati"edsamplingstrategy.

ThebreaksizedistributionschemeinFigure5.3.4providescon"dence andassurancethatthebreakselectionwillresultinappropriatedebris generationbyassigningagreaternumberofbinsforlargerbreaksizes.This practiceensureshighersamplingresolutionofthevery-low-frequencytails wherelargebreaksgeneratemoredebrisandaremorelikelytochallenge ECCSsafetysystems.Althoughmanymorepotentialfailurescenariosare examinedbythisstrategy,noover-conservatismisintroducedbecausethe correspondingweightingfactors(positivedofhorizontallines)are proportionallysmallerwherethesamplingresolutionishighest.Rearrangingthenumberofbinsineachcategorymaycausetresolutionofthetail,ifthelessprobableregion(LargerBreaks)hasfewer binsthantheothercategories.Notein"gure5.3.4thatboththebreak sizeandthecomplementaryannualfrequenciesareplottedonlogarithmic scales.Ifaverycoarsesizeresolutionischosenforthelarge-breakrange, theremaybeavanishinglysmallchancethatanybreaksapproachingthe DEGBconditionwillbeselectedatrandom.Thebreaksizedistribution intheCASAGrandeanalysisisneithertooconservativenorisitnon-conservativeintermsofthedebrisgenerationbecause(1)apredominance oflargerbreakscenariosareexaminedateveryweldforpossiblefailure and(2)strati"edsamplingwithnon-uniformweightingensuresastatisti-callyunbiasedestimateoffailureprobability.Non-uniformsamplingisa commonvariancereductiontechniqueforestimatinglowprobabilityevents whereitisbettertohaveatleastafewfailureeventswithsmallweighting factorsthantohavenofailureeventsatall.2.3.4.6ENPB,Question6aSTPResponse:(Item6a,Page52)TheLOCAfrequencyestimatesareconsistentwithNUREG-1829asde-scribedintheresponsetoAPLAB,CASAGrandeLOCAFrequencies:RAI1 providedintheSTPlettertotheNRCSdatedMay22,2014,ML14149A434.

TheseestimatesaretthanthosethatwouldbeprovidedbytheEPRI RI-ISIprogram.AdditionalexplanationsareprovidedinresponsetoEPNBRAI

6b.2.3.4.7ENPB,Question6bSTPResponse:(Item6b,Page53)NUREG-1829LOCAfrequenciesareusedinthePRAasthebasisforLOCAfrequency.TheRisk-InformedISIprogramhas,asitspurpose,schedulinginspec-tionsbasedontheexpectationfor"ndinga"awforthepurposeofmitigation.

ThestatisticalbasisisthereforeinappropriateforLOCAfrequencyestimates.ThedinthefrequencyestimatesbetweentheGSI-191submittalandtheRI-ISIprogramarediscussedinmoredetailintheattachedreport entitledEPNB-ConsistencyofWeldFrequencieswithRI-ISIProgram,Revision 1(Enclosure1).Tuesday1 stMarch,2016:19:32,Page255of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.5ESGBResponses2.3.5.1ESGB,ChemicalQuestion1a STPResponse:(Item1a,Page53)Althoughchemicalhavenotbeenfoundtobesigni"cantcontributorstoSTPpost-LOCAsumpconditions,CASAGrandeevaluatesachemicalcon-tributionbasedonbreaksizetoprovidesafetymarginintheanalysis.Twolevels ofpossiblecorrelationbetweenconventionalandchemicalinducedheadlosscan bede"ned:(1)therelationshipbetweenconventionaldebrisheadlossandthe attributesofthechemicalhead-lossfactordistributionsappliedacrossLOCA categoriesofSBLOCA,MBLOCA,andLBLOCA,and(2)therelationshipbe-tweenconventionaldebrisheadlossandvaluesofthechemicalhead-lossfactor sampledfromwithinaLOCAcategory.TheLARanalysisdoesincludethe"rst typeofcorrelationbyapplyinglargerchemicalhead-lossfactorstolargerbreaks wheretheconventionaldebrisheadlossisalsoexpectedtobehigher.TheLAR analysisdoesnotenforcethesecondtypeofcorrelation(directcorrelationbe-tweenconventionaldebrisheadlossandchemicalhead-lossfactorssampledforscenarioswithinaLOCAcategory).Uncorrelatedsamplingspreadsthevari-anceoftheexponentialchemicalhead-lossdistributionsacrossallbreak sizesandintroducesanopportunityforsmallbreakstoreceivelargechemical head-lossfactors.ResponsesESGBRAI5andESGBRAI1ddiscussthepos-sibleofenforcinganinversecorrelationbetweenbreaksizeandchemical head-lossfactor.Althoughbothtypeofprecipitateand"lteringcharacteristicsofthedebrisbeddototalheadloss,head-lossfactorsdescribedinLAREnclosure4-3, Table5.6.4wereusedintheCASAGrandeanalysisbecausethedistributions applyvaluesderivedfromthemultiplicativeresponseofaSTPdesign-basis debrisbed(DBA)tothemaximumchemicalload(LAREnclosure4-3,Reference

[53],[1])asdescribedintheresponsetoESGBRAI1c.However,totalhead lossassessedbytheCASAGrandeanalysismaybeunderestimatedforthin bedcases.Thinbedcasesmayhavesmallconventionalheadlossbutstillhave relativelylargechemicalheadloss.Suchheadlossesmaybeashighasthose measuredinSTPDBA(bounding)conditions[Enclosure1,Section4.1and

4.5].Giventhispossiblediscrepancy,analternativeadditivechemically-inducedheadlosscalculationwasperformed[Enclosure1].Thecalculationmethodin-corporatesboththetypeofprecipitateandSTPDBAdebrisbed-per-surface arearesponsetoquantifytotalheadloss.Resultsofthisalternativecalculation supporttheconclusionthatthehead-lossfactorapproachappliedintheLAR islikelyconservativeforconditionswithhighconventionalheadloss[Enclosure 1,Section4.5],butalsodemonstratesthesuspectedunderestimationoftotal headlossforsmallerbreaksfromapplicationofsmallerhead-lossfactorsthan theLBLOCAhead-lossfactor[Enclosure1,Section4.1andSection4.5].How-ever,thisalternativecalculationalsodemonstratesthatadditionofamaximum chemically-inducedheadlossresponseresultingfromprecipitatemassesgener-atedbyWCAP-16530-NPreleaseequationstoconventionaldebrisheadlossmay notincreasefailures[Enclosure1,Section4.5],andtherefore,theriskestimate islargelyunchanged.Tuesday1 stMarch,2016:19:32,Page256of393 DRAFTPART2.RAIRESPONSES(ROUND1)

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.2ESGB,ChemicalQuestion1b STPResponse:(Item1b,Page53)HistogramsofchemicalheadlossvsfrequencyforCASAGrandeCase01(allequipmentoperates)arepresentedbyFigures1and2.Ofthelargebreaks analyzedinCase01,only77%formedathinbedorlargerandtheresulting chemicalheadlossforalllargebreaksrangedbetween0and154.9ftasshown byFigure1.OfthemediumbreaksanalyzedinCase01,1.3%formedathin bedorlargerandtheresultingchemicalheadlossforallmediumbreaksranged between0and0.14ftasshownbyFigure2.SmallbreakLOCAarenotlisted becausenoneofthecasesanalyzedinCASAGrandeCase01formedathinbed orgreater.Figure1:Largebreakchemicalheadlossasafunctionofrelativefrequency(logscale)2.3.5.3ESGB,ChemicalQuestion1cSTPResponse:(Item1c,Page53)Thesingle-parameterexponentialPDFwaschosenforshapeandforconve-nienceof"ttingthedesiredstatisticsofthemeanandatruncatedtailproba-bility.TheexponentialPDFwasnotselectedtomatchanunderlyingphysical process(exponentialPDFiscommonlyusedtodescribetimebetweenfailures) ortoreplicatealargebodyofdata.Inthisapplication,theexponentialPDF isappliedasasubjectiveprobabilitydistributionthatplacesthehighestprob-abilityneartheminimumchemicalhead-lossfactorof1.0andrapidlydeclines acrossallpositivevalues.OtherPDFsincludingWeibull,gammaandbetathat supportunimodal,monotonicallydecliningshapescouldhavebeenadaptedfor thispurpose.Thefollowingdiscussionexplainshowtheexponentialstatistics werespeci"ed.Tuesday1 stMarch,2016:19:32,Page257of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:Mediumbreakchemicalheadlossasafunctionofrelativefrequency(log scale)ThestandardexponentialPDFwasadaptedforusewiththemultiplicative(chemical"bumpup")approachdescribedinLAREnclosure4-3.First,addition ofchemicalstoa"berbedshouldneverreduceexistingheadlossassociated withconventionaldebrisaccumulationattheECCSstrainer,sothePDFwas shiftedtoaminimumfactorof1.0(one).Also,STPCHLEtestswithrepre-sentativealuminumand"berglasssurface-areatowater-volumeratiosindicated thatprecipitationofchemicalproductswasunlikely(LAREnclosure4-3Refer-ence[18-19])WhiletheSTPCHLEtestdonotcoverthefullspaceofLOCA scenarios,theSTPCHLEtestsdosimulatethemostprobablecasesexpected withinthemediumandlargebreakcategories.Therefore,amultipliercloseto 1.0(one)de"nedasthemodeoftheshiftedexponentialPDFrepresentsthe mostprobablecases.ThemeanoftheexponentialPDFwasdeterminedfromevaluationofSTPECCSstrainertesting(LAREnclosure4-3,Reference[53]).Thedesign-basisde-brisbed,havingmaximumdebrisvolumeandmassassociatedwitha7DZOI, wasdeterminedtobethe"bounding"scenarioforSTPbecausethequantityof debrisobservedonthestrainersurfacewassigni"cantlylessthan1/8thick; thereforetheassessmentofathinbedwasunnecessary(LAREnclosure4-3, Reference[53]).Theappliedchemicalprecipitatetestloadwasrepresentativeof precipitatequantitiesgeneratedfrom30-day,continuoussprayexposureofdeter-ministicallyboundingmaterials(1,Table6.3-7).Chemically-inducedheadloss attributabletotheworstcaseprecipitateloadincreasedthedesign-basiscon-ventionalheadlossbyafactorof2.25(LAREnclosure4-3,Reference[53]).For addedconservatism,theSBLOCAmeanwassetequaltothisobservation,while MBLOCAandLBOCAmeanswereincreasedto2.5and3.0,respectively.In thiscontext,conservatismisappliedbecausetheassignedexpectations(means) arehigherthantestdataindicate.ThemaximaoftheexponentialPDFswerecon"rmedtobevaluescapableofproducingaquanti"ablenumberofchemicallyinducedfailuresincombina-Tuesday1 stMarch,2016:19:32,Page258of393 DRAFTPART2.RAIRESPONSES(ROUND1)tionwiththespectrumofconventionalheadlossexperiencedwithineachbreaksize.Thisapproachisjudgedacceptablebecausethemeansforeachbreaktype alreadycapturechemicallyinducedheadlossattributabletoaboundingprecip-itateloadobservedacrosstheboundingdebrisbed.Themaximumfactorsfor SBLOCA,MBLOCA,andLBLOCAchemicalheadlosswere6.8,8.1,and10.7 timeslarger,respectively,thanthe2.25factorincreaseofmaximumheadloss observedintestingunderdesign-basisconditions.Regardingdevelopmentofthesingle-parameterexponentialdistributions,onlythemeanisneededtofullyspecifythedistribution;sothemaximumwas manuallycon"rmedasbeingreasonabletorepresentalllargerfactorswitha cumulativetailprobabilityof1E-5.Themaximumwasnotimposedasanaddi-tionalconstraintonthedistributionitself.

Reference:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.4ESGB,ChemicalQuestion1d STPResponse:(Item1d,Page53)MeansoftheexponentialPDFsweredeterminedfromevaluationofSTPECCSstrainertesting(LAREnclosure4-3,Reference[53])asdiscussedinthe ESGBRAI1cresponse.Insummary,chemically-inducedheadlossobservedin theSTPECCSstrainertesting,attributabletothecompleteadditionofthe worstcaseprecipitateload[1],increasedthedesign-basisconventionalheadloss byafactorof2.25(LAREnclosure4-3,Reference[53]).TheSBLOCAmean wassetequaltothisobservation,whileMBLOCAandLBLOCAmeanswere increasedto2.5and3.0,respectively.AssigningLBLOCAandMBLOCAhigher meansandsettingtheSBLOCAmeanequaltothetestobservationprovides conservatismbecausetheassignedexpectations(means)arehigherthanSTP design-basisstrainertestdataindicate.TailsoftheexponentialPDFsprovide forevenhigherchemicalconsistentwithobservationsofthin-bed strainertests.Analysisofchemically-inducedheadlossusinganadditiveapproachde-scribedinEnclosure1thatcalculatesECCSstrainerheadlossasafunction ofbothprecipitatetypeandSTPdesign-basis-debrisperstrainerareaindicates thatthemeanheadlossfactorusedinthechemicalmodel(LAR,Enclosure 4-3,Section5.6.3)shouldlikelyincreasewithdecreasingbreaksize[Enclosure 1,Section4.1and4.5].TheresultsobtainedbyEnclosure1arealsoinagree-mentwiththecitedobservationswherethegreatestchemicalheadlossfactors areassociatedwiththinnerbedsasdescribedintheresponsetoESGBRAIla.

AlthoughitislikelythatmeansrelatedtosmallerbreaksintheCASAGrande analysisshouldbelargerthanthemeanoftheLBLOCA,increasingthemeans forsmallerbreakswillnotincreaseriskbecausetheLBLOCAmeaninCASA Case01(allequipmentoperates)ishigherthantheexperimentalobservation andmostfailuresoccurforlargebreaks.Asensitivitystudyofsmaller-break meansindicatedthatameanof60forsmallerbreaksdoesnotincreaserisk.A meanof60forsmallerbreaksisamuchlargerchemicalheadlossfactorthan necessarytoadequatelyassessthemultiplicativeeonconventionalheadlossfromprecipitateloading[Enclosure1,Section4.1].ThisconservatismisTuesday1 stMarch,2016:19:32,Page259of393 DRAFTPART2.RAIRESPONSES(ROUND1)alsodemonstratedbythesensitivityanalysisdiscussedintheresponsetoESGBRAI5.Itisnotmoreprobablethatadebrisbedforsmallandmediumbreaks(com-paredtolargebreaks)wouldconsistprimarilyof"ber"nes.Inthehypothetical caseofbreaksthatoccurinsideofacontainmentbuildingthatistotally"lled withLDFG(uniform"berglasseverywhere),everybreakgeneratesthesamevol-umetricproportionof"nes,smallpieces,largepiecesandintactblankets(LAR Enclosure4-3,Reference[46],Table3.1.3).Then,onesetofdebris-sizedepen-denttransportfractionsisappliedforeverybreak(seedebristransportlogic diagramsinLAREnclosure4-3,Figure5.5.2-Figure5.5.4,Pages165-166).

Finally,oncedebrisarrivesatthepoolALL"nesandsmallpiecesareassumed totransport.Thus,thecompositionof"berarrivingatthestrainerisidentical forallbreaksizes,butthevolumesincreasewithincreasingbreaksize.Atthe strainer,allLDFGistreatedwiththepropertiesofindividual"bersforhead losscalculation,regardlessofitsoriginaldestructionsize.

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.5ESGB,ChemicalQuestion2 STPResponse:(Item2,Page54)Table1displaysthemaximumconventionalheadlossandthemaximumtotalheadloss(i.e.,aftertheadditionofchemicalprecipitates)foralltherelevant STPplant-speci"cstrainertestsconductedatARL.Table1alsodisplaysthe correspondingLBLOCAheadlosspercentilesforCASAGrandeCase01(all equipmentoperates).Table1:HeadLossTestMaximumandCorrespondingPercentileConventionalHeadLossTotalHeadLossTestedMaximumPercentileforTestedPercentileforTestCase01LBLOCAsMaximumCase01LBLOCAsTest3,Feb.

>15ft>100%n/an/aTest4,Feb.5.6ft99.96%8.8ft99.51%

Test5,Feb.4.8ft99.81%7.2ft99.34%

Test2,Jul.4.9ft99.83%9.1ft99.53%(Test1inFebruaryandJulywerecleanscreenheadlosstests.Test2inFebruarywasa"beronlytest.)EventhoughtheFebruaryheadlosstestsweresupersededbytheJulyheadlosstests,becausetheFebruarytestsusedwalnut"ourasaparticulatesurrogate (determinedtobenon-representativewithregardtowalnut"our),theCASA GrandeheadlosspopulationforCasaGrandeCase01boundedalltheresults exceptfortheconventionalheadlossofTest3inFebruary.Test3wasterminated afterlargeheadlosses,greaterthan15ft,wereobservedfollowingtheaddition of"ne"brousdebris(2);asalreadystated,thistestusedwalnut"ourasa particulatesurrogateandwassuperseded.AsexpectedtheDBAtestsoccurredTuesday1 stMarch,2016:19:32,Page260of393 DRAFTPART2.RAIRESPONSES(ROUND1)inthetailsofthedistribution.ThefollowingmaximaareforCASAGrandeCase01.Themaximumcon-ventionalCASAGrandeheadlosswas8.2ft.ThemaximumtotalCASAGrande headlosswas161.9ft.Fortheheadlosscomparisonscitedabove,theheadlosseswerenotcorrectedtoacommon"owrateandtemperature,whichisconservativeasstatedinthe responsetoESGB,SteamGeneratorTubeIntegrityandChemicalEngineering

-ChemicalRAI20inSTPlettertoNRCdatedJune25,2014,NOC-AE-14003101,ML14178A481andML14178A485).

References:

1.0415-0100067WN/0415-0200067WN.SouthTexasProjectTestPlanFeb2008.RevisionA.11/24/2008 2.0415-0100069WN/0415-0200069WN.SouthTexasProjectTestReportfor ECCSStrainerPerformanceTestingFeb2008.RevisionA.11/24/2008 3.0415-0100070WN/0415-0200070WN.SouthTexasProjectTestPlan.Re-visionA.8/14/2008.

4.0415-0100071WN/0415-0200071WN.SouthTexasProjectTestReportfor ECCSStrainerTestingJuly2008.RevisionA.11/24/2008.2.3.5.6ESGB,ChemicalQuestion4STPResponse:(Item4,Page54)Asensitivitystudyrelatedtochemicalhead-lossfactortailprobabilitywasnotperformedconcurrentlywithconstantconventionalheadlossbecausethis assumptionwouldnotgeneratemeaningfulrisk-informedresultsthatcouldbe comparedtothebaseline.Baselineconventionalheadlossiscomputedasa functionofwatertemperature,whichcomplicatestherequestedcomparison.

However,astudywasperformedusingCASAGrandeCase01(allequipment operates)chemicalhead-lossfactorswithtailprobabilitiesrangingfrom1E-1to 0.1E-9toassesschangesinreferencedtothebasecase.AsshowninFigure 1,decreasingthetailprobabilityincreasestheratiowhileincreasingthe tailprobabilitydecreasestheratio.Itshouldbenotedthatbecausethe exponentialdistributionisasingle-parameterfunction,theconcurrentmaxima alsodecreasewithincreasingtailprobability.Allcasesexceptthe"rst(1E-1) wererunwiththesamenumberofstatisticalsamplestoillustratethatthe variancegrowsasexpectedwhenthesamesamplesarespreadoverawiderspan oftheparameter.2.3.5.7ESGB,ChemicalQuestion5 STPResponse:(Item5,Page54)TheCASAGrandemodelassessesheadlossfrompossiblechemicalsourcesbyapplyingadistributionofchemicalhead-lossfactorsasafunctionofbreak category(LAREnclosure4-3,Table5.6.4)asdescribedinLAREnclosure4-3, Section5.6.3.Expectedvalues(means)ofthechemicalhead-lossfactordistribu-tionsre"ectthemaximumobservedconventionalheadlossincreaseofadesign basisbed(LAREnclosure4-3,Reference[53])fromthecompleteadditionof aprecipitateloadgeneratedundertheassumptionsof30-day,continuoussprayTuesday1 stMarch,2016:19:32,Page261of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:SensitivityofCDFtochemicaltailprobabilityforCASAGrandeCase01.exposureofdeterministicallyboundingmaterials(LAREnclosure4-3,Reference[53],[1]).AlthoughthedistributionsarecorrelatedtoeachLOCAcategoryby virtueoftheirseparatelyde"nedmeans,magnitudesofthehead-lossare notdirectlylinkedtoestimatedmaterialreleaseforeachbreakconditionas-sessedbyCASAGrande;theconservativechemicalinventoryisassumedforall breakscenarios.Keyparametersthatmayin"uencethechemicalmodelperformanceare(1)useofthe140Ftemperaturecriterionforapplicationofthechemicalhead-lossfactor,(2)selectionofchemicalhead-lossfactormeanvalues,(3)distribution typeand(4)applicationofathin-bed"ltrationcriterion.Ofthefourkeypa-rameterslisted,thetypeofthestatisticsdistributionchosenforimplementation ofthechemicalhead-lossfactorsandtheapplicationofthethin-bed"ltration criteriondonotrisk.Exponentialdistributionswerechosenasasingle parameterdistributionwithashapecontrolledbythemeanandananalytic probabilityintegralforreportingmaximarelatedtoa"xedtailprobability.

Manychoicesoftruncateddistributionscouldbeusedwithequaletopre-servedesiredstatistics.Sensitivityanalysisofthethinbedcriterionresultedin aratioofoneasshownbyFigure1forcontributionsfromsump-strainerfailures computedwhenthethinbedcriterionwasremoveddividedbycontributions fromsump-strainerfailurescomputedforthebaseline,indicatinganulleof thethinbedcriteriononrisk.ToevaluatetheeoftheremainingkeyparametersonCASAGranderesults,sensitivitystudieswereperformed.Thatshowednosensitivitytothe temperaturethreshold.Thesesensitivitycaseswererunwiththefollowingas-sumptions:(1)withthe140Ftemperaturethresholdapplied(bluedots),and(2)withoutatemperaturethresholdapplied(greendots).Allcalculationsshown heredoapplythethin-bedcriterionforapplicationofthechemicalhead-lossfac-

tors.Clearly,sometreatmentofchemicalhead-lossisessentialtoevaluatingriskTuesday1 stMarch,2016:19:32,Page262of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:Riskresultingfromthin-bedcriterion.ThickBed0indicatesthethinbedcriterionwasremoved.Figure2:Summaryofchemicalhead-losskeyparameterssensitivityanalysisandriskasshowninFigure2bycaseBump-UpNotApplied,becausenofailuresinthesumpwerepredictedtooccurbasedonconventionalheadlossalone.Useofthe140Ftemperaturecriterionforapplicationofthechemicalhead-lossfactordoesnotsigni"cantlyanyofthesensitivityresultsortheriskcalculated byCASAGrande(seeESGBRAI8response).Applicationofconstanthead-lossfactorsequaltothecurrentformalmeansoftheexponentialdistributionslowerstheriskforthecaseAllConstantlx FormalMean".However,applicationofconstantmultipliers(2Xand3X)onthe formalmeanincreasestheriskasshownbycasesAllConstant2XFormalMeanTuesday1 stMarch,2016:19:32,Page263of393 DRAFTPART2.RAIRESPONSES(ROUND1)and"AllConstant3XFormalMean.Useofaconstanthead-lossfactorequaltothemeanappliestheexperimentally-observed,worstcase(or2Xto3Xthe worstcase)chemicalheadlossmultiplicativeresponseforallbreaks.Useofotherdistributions,whilepreservingthesameinterpretationofdata,willresultinnearlyidenticalriskresults.However,toshowtheeofal-ternativeprobabilitydistributions,riskratioswereassessedwithatruncated normaldistributionforeachscenario(betweenIandthepresentmaxima)with astandarddeviationofthreetimestheindividualscenariomeanshownascase "Normal(Mean,3XMean)"inFigure2.Althoughtheindividualscenariomeans oftheanalysiswerepreservedinthisdistribution,thelargestandarddeviation approximatesauniformdistributionoverthecompleterange,thus,changingthe intendeduseofthedataandproducinganon-comparativeresult.oftheexponentialdistributionmeanvalueswerealsoevaluatedinthissensitivityanalysisusingareversecorrelationofincreasingchemicalhead-lossfactorwithdecreasingbreaksize.Case"Expo(6,3.5,2.25)"assignedthe SBLOCAmeanto6,theMBLOCAmeanto3.5andtheLBLOCAto2.25.

ThisreversecorrelationpreservestheSTPexperimentallyobservedmultiplica-tivechemicalhead-lossresponseoftheLBLOCA(LAREnclosure4-3,Reference

[53])andincreasestheothermeansasafunctionofdecreasingbreaksize.This reversecorrelationre"ectstheobservedthin-bedwherethemultiplica-tiveresponseofprecipitateloadingonsmallerbreakdebrisbedsisgreaterthan thatobservedfromthesameprecipitateloadingonlargebreakdebrisbeds

[Enclosure1,Section4.1].Althoughthemeanswerelargerforsmallerbreaksas comparedtothemeanofthelargebreak,riskdecreasesbecausetheconservatism associatedwiththeLBLOCAmeanwasdecreasedandbecausetheincreasein meansassociatedwiththeSBLOCAandMBLOCAbreakswerenotst toinducefailure.Afurthersensitivitystudyindicatesthatthemultiplieronthe MBLOCAconditionmustbehigherthan60toincreasetheriskassignedby CASAGrandeCase01(allequipmentoperates).TheSBLOCAheadlossfactor inthissensitivity,althoughhigherthanassumedintheLAR,doesnotin"uence theriskbecausenoneoftheSBLOCAscenariosformathinbed.

References:

1.Westinghouse,"SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,"WestinghouseElectricCompany,December2006.2.3.5.8ESGB,ChemicalQuestion6 STPResponse:(Item6,Page54)TheCASAGrandetreatmentofchemicaldoesnotdistinguishtherel-ativecontributionsfromsprayedmaterialsandsubmergedmaterials.ThePDF meanvaluesofthechemicalhead-lossfactorsusedintheCASAGrandeanal-ysis(LAREnclosure4-3,Section5.6.3)toinduceamultiplicativeincreasein conventionalheadlossarebasedonSTPtestingofaworst-caseprecipitateload acrossadesignbasisbed[1].Theworst-caseprecipitateloadwasgeneratedas-suming30-daysofsprayoperation[2,Table6.3-7],[1,Page54].WhiletheCASA Grandeanalysisassumesthatallspraysaresecuredatapproximately6.5hours withrespecttostrainer"owrate,thechemicalhead-lossfactorsre"ectchemical headlossattributableto30daysofcontinuoussprayonallexposedsurfacesand 30-daysofcorrosionforallsubmergedmaterials.Tuesday1 stMarch,2016:19:32,Page264of393 DRAFTPART2.RAIRESPONSES(ROUND1)Giventheassumed30-dayinventoryofchemicalproducts,spraytimingas-sumedinCASAGrandedoesnotthechemicalsourcetermortheprob-abilityofprecipitation,sonosensitivitieswereperformedonthespraytimeto addressthisRAI.

References:

1.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting(66-9088089-000),August2008.2.Westinghouse,SouthTexasProjectGSI-191 ChemistryEvaluationCN-CSA-06-6,WestinghouseElectricCompany, December2006.2.3.5.9ESGB,ChemicalQuestion8 STPResponse:(Item8,Page55)TheCASAGrandemodeldoesnotexplicitlyincludecalciumsourcessuchasconcretedust,concreteablatedbythejet,andotherplantmaterialssuch asinsulation,butrather,appliesaseparatechemicalhead-lossfactorforeach LOCAcategorytoincreaseheadlossforallanticipatedchemicalproducts.The head-lossfactormeansarebasedonthemaximumheadlossobservedduring STPECCSstrainertestingofa30-dayworst-caseprecipitate(includingboth calciumandaluminum)load(LAREnclosure4-3,Reference[53],[1])acrossa designbasisbed.Somepipebreaksmayproduceenoughcalciumtoformprecipitatesinthesumppoolpriortobulk"uidtemperaturesreaching140F(approximately17.8hrforSBLOCAandMBLOCA,5.0hrforLBLOCA).Insuchcases,calcium leachingratesmaybettoexceedcalciumphosphatesolubilityatpool temperaturesandpHvalueswithinthesetimeperiods.Ahighertemperaturethresholdthatpermitsimmediatechemicalhead-lossforCASAGrandeCase01(allequipmentoperates)increasesthetotal riskbyapproximately4%.Alloftheadditionalscenariofailuresareattributed tohigherchemicalinducedheadlossatthestrainer.Coredebrisaccumulation doesnotdependonthechemicalhead-lossfactors.Analternativechemically-inducedhead-losscalculationdescribedinSection4.5ofEnclosure1thatisadditiveandincorporatesboththetypeofprecipitate andthedebrisbedareatoquantifytotalheadloss,alsoshowsthatpossible precipitateformationpriorto140Fwouldinducelittleincreaseintotalhead loss.

References:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.10ESGB,ChemicalQuestion9 STPResponse:(Item9,Page55)Althoughchemicalhavenotbeenfoundtobesigni"cantcontribu-torsinSTPpost-LOCAsumpconditions,CASAGrandeincludesuncertainty forchemicalcontributiontoheadlossasarandomvariablemultiplierwitha meangreaterthan1.Assuch,nomodelsofdissolutionorsolubilitylimitsap-peardirectlyintheCASAGrandeanalysis,souncertaintiesassociatedwith adissolutionmodelandsolubilitylimitswerenotexaminedexplicitly.Expo-nentialprobabilitydensityfunctions(PDFs)de"nedforthechemicalhead-lossTuesday1 stMarch,2016:19:32,Page265of393 DRAFTPART2.RAIRESPONSES(ROUND1)factorsdescribethemagnitudeofthehead-lossthatwillbeobservedafterchemicalproductsform.Themagnitudeofhead-lossisindependentof dissolutionprocessesandsolubilitylimits,sotheseconsiderationsarenotfac-toredintothePDFsde"nedforchemicalbump-upfactors.Asdescribedinthe responsetoESGBRAI1c,thechemicalhead-lossfactormeansre"ectthemaxi-mumobservedconventionalheadlossincreaseofadesignbasisbed[1]fromthe completeadditionofaprecipitateloadgeneratedunder30-day,continuousspray exposureofdeterministicallyboundingmaterials(1,2]andthesingle-parameter exponentialPDFwaschosenforshapeandforconvenienceof"ttingthedesired statisticsofthemeanandatruncatedtailprobability.However,thecriterionof

140+/-5Fforimplementationofthebump-upapproachwaslooselyderivedfromindustrypracticefordelayedonsetofprecipitationbasedonaluminumsolubil-ity[3,4]anddoesacknowledgethatprecipitationtemperaturedependsonthe productsinquestionandonthechemicalenvironment.Applicationoftheprecipitationtemperatureistheonlyconsiderationofsol-ubilitypresentintheSTPLARanalysis.AsdescribedintheresponsetoESGB RAI10,acceptabilityofthe140

+/-5FtemperaturecriterionwasexaminedasafunctionofuncertaintyintheexpectedrangeofSTPpost-LOCApH,pool temperature,andvariableinventoryofmaterialexposure(LAREnclosure4-3, Reference[201).WhileLAREnclosure4-3,Reference[20]concludedthatalu-minumprecipitationwasunlikelytooccurwithintheparameterrangesexamined priorto140

+/-5F,thereferencedidnotexaminepotentialofotheruncertain-tiesrelatedtomaterialreleaserates,chemicalmodeling(thermodynamicand kinetic)calculationsusedtoassesssolubility(equilibriumcoets,enthalpy, speci"edreactions,andtime)andcalciumprecipitationpriorto140

+/-F.Sincealluncertaintiesassociatedwiththecriterionof140

+/-5Fthatwaslooselybasedonaluminumsolubilitywerenotfullyaddressed,thepossiblein-creaseinriskthatcouldoccurthroughtheuseofahighertemperaturecriterion wasexaminedasasensitivitycase.Useofahighertemperaturethresholdthat permitsimmediateapplicationofthechemicalhead-lossfactorsincreasesthe riskofCASAGrandeCase01(allequipmentoperates)byapproximately4%as discussedintheresponsetoESGBRAI8.Thisincreaseisnotlikelytoposea practicalconcern.

References:

1.AREVA,SouthTexasProjectTestReportforECCSStrainerTesting(66-9088089-000),August2008.2.Westinghouse,SouthTexasProjectGSI-191ChemistryEvaluation CN-CSA-06-6,WestinghouseElectricCompany,December2006.

3.AluminumSolubilityinBoronContainingSolutionasaFunctionofpHand Temperature,Adams#ML091610696,September2008.

4.Entergy,GL2004-02FinalSupplementalResponsesAdams#ML082700499,

2008.2.3.5.11ESGB,ChemicalQuestion10 STPResponse:(Item10,Page55)Poolchemistry,poolpHandtheamountsofaluminumandcalciumwereconsideredintheadoptionofthechemicalprecipitationthresholdtemperature andinthede"nitionofthechemicalhead-lossfactors.However,thesefactorsdoTuesday1 stMarch,2016:19:32,Page266of393 DRAFTPART2.RAIRESPONSES(ROUND1)notappearexplicitlyinCASAGrandeinput.TheconditionsusedtocontrolapplicationofchemicalbumpupapproachintheCASAGrandeanalysisareatemperatureof140

+/-5Fwhena"berbedgreaterthanorequalto1/16forms,asindicatedinLAREnclosure4-3.The choiceof140

+/-5Fasachemicalprecipitationtemperatureisnominallybasedonindustrypracticefordelayedonsetofaluminumprecipitation[1,2],onreview ofCHLEtanktestresults(LAREnclosure4-3,Reference[18,19])andoneval-uationofmultipleWCAP-16530-NPprecipitatereleasecalculationsunderSTP post-loss-of-coolantaccident(LOCA)scenarios(LAREnclosure4-3,Reference

[20]).MultipleWCAP-16530-NPcalculationswereperformedtocon"rmthatthe precipitationonsettemperatureadequatelyassessesuncertaintyrelatedtopH, poolchemistryandmaterialexposurethatprecipitategeneration(LAR Enclosure4-3,Reference[20],Tables1-3).TheWCAP-16530-NPcalculations showthatthelikelihoodofaluminumprecipitationabovethetemperatureof

140+/-5FwithvariablepoolpH,poolchemistryandvariablematerialinvento-riesislow(LAREnclosure4-3,Reference[20],Table4).TheWCAP-16530-NP calculationsofLAREnclosure4-3,Reference[20]didnotexplorespraydurations longerthan6.5hoursanddidnotaccountforzincrelease.However,chemical head-lossfactordistributionswerebasedonconservativechemicalproductin-ventoriesasdescribedbelow.Exponentialprobabilitydensityfunction(PDF)meanvaluesappliedaschem-icalhead-lossfactorsprovideaconservativelylargechemicalheadlossresponse thataccountsforexclusionofzinc-relatedchemicalandboundsthereal-isticevaluationof6.5hoursofsprayexposure.Conservatismisensuredbecause themeanheadlossvalues(LAREnclosure4-3,Table5.6.4)re"ectthemul-tiplicativeincreaseofconventionalheadlosscausedbyaworstcasechemical precipitatetestloadappliedtoadesign-basisdebrisbed(LAREnclosure4-3, Reference[53],[3]).Thisworstcaseprecipitateloadcorrespondsto30-dayspray exposureofdeterministicallyboundingaluminum,siliconandcalciumbearing materialquantities[3].Theexperimentallyobservedmultiplierof2.25wasas-signedtosmallbreaksandthenincreasedforlargerbreaks.Also,theexpected STP-post-LOCAmaterialreleasesdeterminedbycalculationslistedinLAREn-closure4-3,Reference[20]aremuchlessthanthe30-daychemicalinventoryused instrainertesting(LAREnclosure4-3,Reference[53],[3,Table6.3-7]).Chem-icalhead-lossfactorsbasedonaboundingchemicalheadlossresponse aredependentonbreaksizeregardlessofrealisticspraydurationandmateri-alsexposed,whichfurtherenforcestheconservativeinterpretationofthemean values.

References:

1.Bahn,C.B.,Kasza,K.E.,Shack,W.J.,andNatesan,K.AluminumSol-ubilityinBoronContainingSolutionsandaFunctionofpHandTemperature, ADAMS#ML091610696,ArgonneNationalLaboratory,September,2008.

2.Entergy,GL2004-02FinalSupplementalResponses,Adams#ML082700499, September2008.

3.Westinghouse,SouthTexasProjectGSI-191ChemistryEvaluation CN-CSA-06-6,WestinghouseElectricCompany,December2006.Tuesday1 stMarch,2016:19:32,Page267of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.5.12ESGB,ChemicalQuestion14aSTPResponse:(Item14a,Page57)Uncertaintiesfromradiationonprecipitateformationwerenotexam-inedbecausein-situcorrosionanddissolutionprecipitateswerenotobservedin prototypicaltestsolutions(LAREnclosure4-3,Reference[18,19]).2.3.5.13ESGB,ChemicalQuestion14b STPResponse:(Item14b,Page57)Uncertaintiesfromradiationondebrisbeddegradationwerenotex-aminedbecauseTriNuclearpolyesterand"berglass"ltercartridgesusedbySTP haveaspeci"edmaximumaccumulateddoseof106radstoavoid"lterdegra-dation[1,2].These"ltersareusedinthespentfuelpoolandcoretoremove particulatesandmaintainwaterpurityspeci"cations.Itwasinitiallyassumed thatthedoselimitwasrecommendedtoavoiddegradationof"berglass,when infact,itisrecommendedtoavoiddegradationinmodelsthatcontainpolyester (hydrocarbon)"ltermediathatismoresusceptibletoradiationdamagethan glass.Thefollowingorder-of-magnitudeargumentdemonstratesitisunlikely that"berglassdebrisreceivesadosegreaterthan106radsfromcruddeposition

alone.Thespeci"cactivityofcrudpresentatSTPisunknown,buthealthphysicssurveysofspent"ltersthatcollectcrudarecommonpractice.Itisimportantto notethatCo-58andC0-60,signi"cantdosecontributorsfromcrud,arehighly solubleintheRCSsolutionandarenotcapturedinthe"lters.Similarly,these isotopeswouldnotremainresidentinthedebrisbed.Crudconstituentsolubility doesnottheaccuracyofthisanalysis,butitisanimportantconsideration beforeadoptingcrudactivityvaluesreportedintheliterature.Themassofcrudcollectedin"lterscanberelatedtothethresholdof106radtojudgewhether"berglassdebriscanreceiveahigherdose.Itisassumedthat thephysicalformofcrudcapturedinthebedisidenticaltotheformcaptured inthe"lters.Thedoseto"berglassdebriscanbeapproximatedas D bed=Mcrud bedA)crudbed T bed Mfiber bed (A)where: Mfiber bed=massof"berglassinthedebrisbed Mcrud bed=massofcrudinthedebrisbedA)crud=energyreleaserateperunitmassforspeci"cactivity A andaveragegammaenergybed=eeabsorptioninthe"bermat T bed=bedexposuretimeThedoseratemeasuredbyahealthphysicssurveymetercanbeapproxi-matedasDfit=McrudfiltA)cruddetect M detect (B)where: Mcrudfilt=massofcrudinthe"lterTuesday1 stMarch,2016:19:32,Page268of393 DRAFTPART2.RAIRESPONSES(ROUND1)A)crud=energyreleaserateperunitmassforspeci"cactivity A andaveragegammaenergydetect=eecaptureofthesurveymeter M detect=eemassofthedetectorSolvingEquationAandBforthecommonenergyreleaserateperunitmassA)crudandisolatingcrudmassinthe"ltergives Mcrudfilt=Dfit Mcrud bedbed T bed M detect D beddetect Mfiber bed(EquationA)NumericparametersusedtoevaluateEquationCareshowninTable1.AconstantmaximumcrudinventoryisassumedintheSTPLARanalysis, butthedebrisquantitycanvary.Concentratingtheassociatedenergyrelease inminimumdebrismassrepresentsamaximumexposuretoradiation,soa 1/16-in.equivalentthinbedwasassessedforcomparisonpurposes.Assuming lowbedcompactionequaltothemanufactureddensityfurtherconcentrates theradiationdose.Relativelythinporousmediaarenotwellcoupledtothe particulateradiationsourcefortgammaenergyabsorption,soanee absorptionfractionof0.1wasassigned.Similarly,ahand-heldgammasurvey meterhaspoorcollectionfora30-in.long,6-in.diameterstainlesssteel "ltercartridgecontaininganannular,cylindricalradiationsource,soavalueof 0.15wasassigned.Table1:Parametersfor"berglassdoseassessment.bedpackingdensity2.4lbm/ft3maxdose106rad(J/kg) bedabsorbfract0.1 bedthick1/16thin onestrainerarea1818.5ft2

1. strainers3 debrisexposuretime30days crudmassinbed24lbm edetectormass100g detector0.15 max"lterdoserate20rad/hrUndertheassumptionslistedinTable1,themassof"berglassdistributedonall3strainersisapproximately31kgandthecrudmassestimatedtobeon the"lterislessthan1gram.Forcrudburstcleaningprocedurestobee relativetothe24Ibmmaximuminventory,"ltersmustcollectupto1-pound quantities.Therefore,itisnotlikelythat"berglassinthedebrisbedcanreceive adosefromaccumulatedcrudthatmeetsorexceeds10 6rad.Apredicted"ltermassof1pound(450g)correspondstoadebris-beddoseofonly750rad.

RCS"ltersatSTParenotcommonlyweighedformassincrease,soquantitative con"rmationoftheseobservationsisnotavailable.

References:

1.TriNuclearCorp.UnderwaterFilter/VacuumUnitsAssembly&Operat-ingInstructions.December2012.Tuesday1 stMarch,2016:19:32,Page269of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.TriNuclearCorp.TNC-019-02standard"lterdrawingandproductde-scription.2.3.5.14ESGB,ChemicalQuestion14c STPResponse:(Item14c,Page57)Uncertaintiesfromchemicalsleachedfromunquali"edcoatingsatSTPwerenotconsideredexplicitlyintheassessmentofpotentialchemicalHowever, exponentialdistributionsofchemicalhead-lossfactorsappliedintheanalysisdo permitchemicalhead-lossethatexceedlevelsthatareexpectedfrom30-dayinventoriesofaluminumandcalciumcompounds.Someofthismargincanbe interpretedasvariabilityintroducedbyanychemicalsleachedfromunquali"ed coatings.Thephenomenaofunquali"edcoatingsdegradationintoagelatinous debrissourcewasnotconsideredinthechemicalanalysisthatsupported theSTPCASAGrandeevaluation.Itisgenerallyassumed(LAREnclosure 5,Reference[3])thatunquali"edcoatingsfailintoconstituentsolidswithout furthercontributiontothechemicalenvironment.CoatingstestedinLAREnclosure5,Reference[3]areassumedtobesimilartothosedocumentedinSTPunquali"edcoatingsdocumentation(LAREnclo-sure4-3,Reference[12]).However,sincedetailedproductinformationassociated witheachtypeofcoatingwasnotavailable,onlygeneralcomparisonsweremade betweencoatingcategoriesofthoseatSTPandthoselistedinLAREnclosure 5,Reference[3].2.3.5.15ESGB,ChemicalQuestion15 STPResponse:(Item15,Page57)TheCASAGrandemodeldoesnotdetermineachemicalsourcetermfortbreaksizes,anditdoesnotassesssmallerbreakconditionsthatmay thecalciumandaluminumconcentrationswithintheanalysis.Rather,the CASAGrandemodelassessesheadlossfrompossiblechemicalsourcesbyapply-ingarangeofchemicalhead-lossfactorsasafunctionofbreakcategory(LAR Enclosure4-3,Table5.6.4)thataccountforchemically-inducedheadloss(LAR Enclosure4-3,Section5.6.3).Therangesofappliedchemicalhead-lossfactors arebasedonstrainertestingconductedusingadesign-basisdebrisbedasde-scribedbelow,adequatelyboundchemicallyinducedheadlossfromaspectrum ofchemicalsourceterms.Deterministicanalysesalsodonottypicallyconsider howasmallerbutpotentiallymorefocusedjetmaythecalciumandalu-minumconcentrations.Thechemicalhead-lossfactorsrangefromrepresentativetohighlyconserva-tivemultipliersandareusedinbreak-speci"cexponentialprobabilitydistribu-tionsthatwereadaptedforusewiththechemicalbumpupapproachdescribed inLAREncl.4-3,Section5.6.3.AsdescribedintheresponsetoESGBRAI1c, themostprobablehead-lossfactors,basedonexperimentalobservation(LAR Enclosure4-3,Reference[18,19]),correspondtothemodeof1.0(one)forall breaks.Thechemicalhead-lossfactormeansre"ectthemaximumobservedcon-ventionalheadlossincreaseofadesignbasisbed[1]fromthecompleteaddition ofaprecipitateloadgeneratedunder30-dayandcontinuoussprayexposureof deterministicallyboundingmaterials(LAREnclosure4-3,Reference[531,[1]).

ThemaximaoftheexponentialPDFswerecon"rmedtobevaluescapableofTuesday1 stMarch,2016:19:32,Page270of393 DRAFTPART2.RAIRESPONSES(ROUND1)producingaquanti"ablenumberofchemicallyinducedfailuresincombinationwiththespectrumofconventionalheadlossexperiencedwithineachbreaksize andwereatleast6.8timeslarger,thanthemeanfactorofagivenbreaksize PDF.Theexponentialdistributionswerenotadjustedforlowerchemicalinven-toriesthatmightbeevolvedduringshorteraccidentperiodsorfortheabsence ofspraysinsmallbreakscenarios.

Reference:

1.Westinghouse,SouthTexasProjectGSI-191ChemistryEvalua-tionCN-CSA-06-6,WestinghouseElectricCompany,December2006.2.3.5.16ESGB,ChemicalQuestion16 STPResponse:(Item16,Page57)Yes,Tables2.5.34and2.5.35inVolume6.2summarizetheresultsofthe30-dayreleasedmaterialconcentrationsandtheevaluationofprecipitateoccurrence underspeci"edconditions(LAREnclosure4-3,Reference[20],Table4and5).

ThepHpro"lesusedinthesimulationssupportingthetableswerealinear responseinTSPdissolutiontimethatstartedatapHof4.5androsetothe steady-stateminimum(pH7.0)ormaximum(pH7.3)over80minutes(LAR Enclosure4-3,Reference[20]).ThesteadystatepHwasdeterminedfromthe rangeofTSPmasswithincontainment[2]andthebestestimatewatermass forLBLOCA(LAREnclosure4-3,Reference[14],Table6.2).Theminimum andmaximum"berquantitiesandwatervolumeforeachbreaksizethatwere usedforWCAP-16530-NP-Acalculationsandtheassumedplantconditionis displayedinTable1(LAREnclosure4-3,Reference[20],Table1).Theamountof LDFGwasdeterminedfromtheCase01(allequipmentoperates)CASAGrande simulation.PlantconditionsforwatervolumesweredeterminedfromSTPPost-LOCAWaterVolumeAnalysisat130F(LAREnclosure4-3,Reference[14],Table5.9).Table1:WCAP-16530-NP-AInputandPlantConditionComparisonMinLDFG(ft3)MaxLDFG(ft3)MinWaterVol.(ft3)MaxWaterVol.(ft3)WCAPPlantCon-ditionsWCAPPlantCon-ditionsWCAPPlantCon-ditionsWCAPPlantCon-ditionsSBLOCA001012.862,70063,31475,92176,665 MBLOCA1006010966,41167,06279,63280,412 LBLOCA600.72,3852421.466,41167,06279,63280,412Withtheexceptionofthemaximum"berglassquantityforMBLOCAsce-narios,theboundsoftheanalysiswouldnotbesigni"cantlylargerthanthose examined.TheunderestimatedMBLOCAmaximum"berglassquantitymayun-derestimatesimulatedcalciumandaluminumreleaseforMBLOCAcases.An-otherslightdnotaccountedforinthesimulationisassociatedwiththe pH.Completedissolutionwasassumedtooccurwithin80minutes,but thepHpro"leforeachbreaksizemaybeslightlytbecauseofvariable RWSTdraintime.However,onlythe1.5-inchbreak(LAREnclosure4-3,Page 1-10)takeslongerthan80minutestodrain.Therefore,mostbreakswillreach thesteadyboundssoonerthanindicatedbytheanalysis.Also,the"nalsteady statepHboundswerebasedonLBLOCAbestestimatewatermass,the"nal steadystatepHboundsforaMBLOCAarecorrectlyassessedsincethebestes-Tuesday1 stMarch,2016:19:32,Page271of393 DRAFTPART2.RAIRESPONSES(ROUND1)timatewatermassforaMBLOCAandLBLOCAarethesame((LAREnclosure4-3,Reference[14],Table6.2).However,therewouldbeapproximately11%less solutioninaSBLOCAthaninaLBLOCAscenario.Thisfactsuggeststhatthe pHrangeexaminedmayhavebeenslightlyunderestimatedinthesimulationof smallbreaks.ThereforethepHrangeofaLOCAeventcouldbeslightlylarger thanthe0.3pHunitspredicted.ThepHrangemayhavebeenslightlyunderestimatedinthesimulationofSBLOCA,duetohavingabout11%lesssolutioncomparedtoLBLOCAsce-narios.BecauseSBLOCAsdonotchallengeGSI-191successcriteria,andthe 11%decreaseinpoolsolutiononlyresultsina5%relativeincreaseinTSP concentration,thepH(andpHrange)isvalidandencompassesallscenariosof

concern.2.3.5.17ESGB,ChemicalQuestion18a STPResponse:(Item18a,Page58)ThesupplementaryinformationprovidedbyVolume6.2,"Item5.a.6:corro-sionanddissolutionModel,"onlyprovidesgeneralizedinformationandwasnot directlyappliedintheCASAGrandeanalysis.Thesjudgmentthatallowssubstitutingaluminumoxyhydroxideforsodiumaluminumsilicateisnotrelevanttosolubilitywhenevaluatingtheforma-tionofanaluminumbasedprecipitateinpost-LOCA"uidscontainingdissolved aluminum.Thetextdidnotconveytheintendedconceptthattheuseofalu-minumoxyhydroxidesolubilitytopredicttheformationofsodiumaluminumsil-icatewasassumedtobeadequateforageneralassessmentofaluminumproduct formationoraluminumsolubilitysincesolubilitylimitsofthesetwocompounds wereshowntobesimilar(i,Section6,items6and7).2.3.5.18ESGB,ChemicalQuestion18b STPResponse:(Item18b,Page58)LAREnclosure4-3,Reference[20]referencedanaluminumsolubilitydeter-minedfromtheuseofVisuaIMINTEQv3.0withSTPspeci"csolutionchem-istryatapHof7.0andtemperatureof140OF.Usingasolubilityof2.7mg/L obtainedfromANLsequationwouldincreasethelikelihoodofaluminumpre-cipitationunderconditionsexaminedbyLAREnclosure4-3,Reference[20]and wouldhavelikelyresultedinahighertemperaturecriterionforonsetofprecip-itationintheCASAGrandeanalysis.However,asdiscussedintheresponseto ESGBRAI8,theuseofahighertemperaturethreshold(orimmediateimple-mentationofthemultiplicativeheadlossfactors)doesnotsigni"cantly riskassociatedwithCASAGrandeCase01(allequipmentoperates).2.3.5.19ESGB,ChemicalQuestion18c STPResponse:(Item18c,Page58)Figure2.5.34captionwasmislabeled.The"guredoesreferencecalciumphos-phatesolubility(LogKof-28.25andH rxnof-87kJ/mol)at185FrangingfrompH7.0to7.30.

Reference:

1.Westinghouse,WCAP-16785-NP,Rev0EvaluationofAdditionalInputstotheWCAP-16530-NPChemicalModel,WestinghouseElectricCompany,MayTuesday1 stMarch,2016:19:32,Page272of393 DRAFTPART2.RAIRESPONSES(ROUND1) 2007.2.3.5.20ESGB,ChemicalQuestion21 STPResponse:(Item21,Page59)AsstatedinSection2.2.11,thequantityofcrudassumedintheanalysisis24Ibm(LAREnclosure4-3,Reference[13]).WithinCASAGrande,crud isconsideredtobea15-

µmparticulate"newitha100%transportfractionunderallLOCAscenarios.Thefullcrudinventoryisintroducedduringthe"rst timestepofeachscenario,andcrudtransportstothestrainersinproportion totheirvolumetric"ow.Uponarrivalatastrainer,crudishomogenizedwith allotherparticulatesand"bertoformcompositedebrispropertiesthatare enteredinthehead-losscorrelation.STPdoesnotquantifytheamountofcrud releasedduringthecrudburstevolution.Theobjectiveofthecrudburstisto minimizeradiationworkerdose.Theenessofthecrudburstevolutionis measuredbydosecomparedtopreviousevolutions.Unlikeamomentum-driven processthatmaydislodgecrudfromRCSsurfaces,hydrogenperoxideisusedin achemicalprocesstomaximizeremovalofcrud.Anestimateofcrudquantity availableinanoperatingcycleismadeforthepurposeofcoredesignusing theEPRIBOA3.1software[1]toevaluatetheimpactofcrudinducedpower shift.BOAestimatesthecruddepositonthefuelandsteamgenerators.7STP BOAestimatesshowthattheSTPUnit1predictedinventoriesarelessthanthe industrynominal,sothe24Ibmcrudassumed(LAREnclosure4-3,Reference

[13])inCASAGrandeisappropriateandconservative.

Reference:

1.Boron-inducedAnomaly(BOA)RiskAssessmentTool:Version2.0.EPRI,PaloAlto,CA,1014961,December2007.2.3.5.21ESGB,Coatings:Question1 STPResponse:(Item1,Page59)Theunquali"edcoatingssizedistributionofTable2.2.18(LAREnclosure4-3)wastakenfromLAREnclosure4-3,Reference[12],Table7,Page32.This calculationreferencestheepoxysizedistributionsfrompaintchipcharacteri-zationofDBAcoatingstestingdocumentTXUPaintChipCharacterization, (1).AutoclavetestingwasconductedonTXU(ComanchePeak)suppliedcoat-ingsamplestodeterminesizedistributioncharacteristicsofunquali"edcoatings debris,measuredbyfailedmass,failedcharacteristicsize,andqualitativefailed shape(2).ResultsoftheTXUPaintChipCharacterization(1)document includedmasspercentagesforeachofthesize/qualitativeshapecategoriesof epoxy.Thesefailedmasspercentagesandsize/qualitativeshapecategoriesare representativeoftotalfailedinventoryfromtheundocumented(assumedun-quali"edcoated)autoclavetestedsamples.Theresultsofthetestwereapplied toestimatethesizedistributionoffailedepoxyforagivenvolumeofunquali"ed

coatings.

References:

1.ALION-REP-LAB-TXU-4474-02.TXUPaintChipCharacterization.Re-vision0:October2007.2.Keeler&LongPPGReportNo.06-0413,DesignBasisAccidentTestingofCoatingSamplesfromUnit1ContainmentTXUComanchePeakSES,AprilTuesday1 stMarch,2016:19:32,Page273of393 DRAFTPART2.RAIRESPONSES(ROUND1) 2006.2.3.5.22ESGB,Coatings:Question2 STPResponse:(Item2,Page59)AZOIwascreatedforeachofthefourdtbreaksizesinthreeboundinglocationswhichdeterminearealisticmaximumamountofsurfaceareaforthe tepoxy,polyamideprimer,andIOZcoatings.Duetothetinner diametersofpipes,the4DZOIradiusisusedfortheepoxyandinorganiczinc (IOZ)quali"edcoatingsassuggestedbyWCAP-16568-P.2.3.5.23ESGB,Coatings:Question3 STPResponse:(Item3,Page60)ThefailurefractiondistributionsgiveninLAREncl.5(Pgs.12-17)displaytheresultsofunquali"edcoatingsfailureanalysis(LAREncl.4-3,Ref.[12]),

andshowthatunquali"edcoatings(investigatedintheSTPevaluation)have probablefailurefractionranges.Thisfailurefractionanalysisisusefulbecause itshowsthatfailurefractionsotherthan100%areprobableforunquali"ed

coatings.However,thefailurefractionanalysisisnotusedintheCASAGrandeeval-uation.Allunquali"edcoatingsfailurefractionswere(assumed)setto100%.2.3.5.24ESGB,Coatings:Question4 STPResponse:(Item4,Page60)Yes.Forunquali"edcoatingsnotlocatedintheuppercontainment,100%ofthecoatingsareassumedtofailandareassigneda100%failurefractioninthe CASAGrandeinputdeck.Theamountofunquali"edcoatings(notinuppercontainment)availablefortransportis100%.However,thefailedunquali"edcoatings(notinupper containment)aresubjecttorecirculationtransportfractionsthatdesignatethe fraction(ofunquali"edcoatings)trappedassedimentandthefractionthat activelyrecirculatesinthecontainmentpool.Yes.100%ofthecoatingsthatarecalculatedtotransporttothestrainerareassumedtoarriveatthestrainer.Theunquali"edcoatingsquantitiescalculated totransporttothestrainerarethequantitiesthathavealreadybeenreducedor multipliedbythefailure(100%)andtransportfractions(location,recirculation).CASAGrandeintendedthatthemassofunquali"edcoatingsdesignatedasactivelyrecirculatinginthepoolbeaddedtothepoolatuniformrateover36 hours;however,acodelevelerror(CASAGrandev1.6ReleaseNotes,Error Report#04)forcedtheassumptionthatallactivelyrecirculatingmaterials, includingunquali"edcoatings,arriveinthepoolwithinthe"rst10minutesfor allscenarios.Additionalinformation ItshouldbeunderstoodthataccumulationofsuspendeddebrisdoesnotbeginuntilECCSrecirculationbegins.Afurtherclari"cationtothequestion statementisthatuniformdebrisadditiontothepoolataconstantrateisnot thesameasauniformarrivalrateonthestrainer.Therateofaccumulationon thestrainerisdrivenbytotalrecirculation"owrate,whichmaychangewith

time.Tuesday1 stMarch,2016:19:32,Page274of393 DRAFTPART2.RAIRESPONSES(ROUND1)Unquali"edcoatingsfailurefractions/percentagesdiscussedinLAREncl.5arebasedonanalysisofElectricPowerResearchInstitute(EPRI)data(1) performedinLAREncl.4-3,Ref.12(p.1-1).TheEPRIunquali"edcoatings study(i.,pp.4-5)reportsthepercentageofcoatingdetachmentfromsubstrates ofmultipleplant-providedsamplesfortcoatingtypes(e.g.epoxy,alkyd, etc.)subjecttodesignbasispreparation(radiationexposure),andautoclave conditions(temperature,pressure,andspray).TheEPRIdetachmentdatawas usedasthebasisforthefailurefractionsdescribedinLAREncl.5(p.11).CASA GrandedidnotusethesefailurefractionsfortheSTPanalysisdescribedinLAR Encl.43,intheirplace,100%failurewasassignedforallunquali"edcoatings.Theunquali"edcoatingsfailuretimingwascalculatedfromtheEPRIdata(pp.4-5)(1)inLAREncl.4-3,Ref.[12](p.25).ThetiminganalysisofLAR Encl.4-3,Ref.[12](p.25)isbasedonvisualinspectionof"ltersusedinthe EPRIunquali"edcoatingstesting(p.4-3)(1).These"lterswerechangedin uneventimeincrementsduringtheEPRIautoclavetesting,andthe"lterswere rankedfrom0to10bythedegreeofdiscolorationfortheirrespectivetime increment.Theresultsoftheanalysiswereextrapolatedto30dayswithaforced (normalized)cumulativefailureof100%overalltimeincrements.Awashdown fractionof6.0%(LAREncl.4-3,Ref.[12],Table6,p.30)wasassignedinCASA Grandeforallunquali"edcoatingsthatfailinuppercontainmenttoaccountfor spraysbeingsecuredwithin24hours.The6.0%washdownfractionissupported byanalysisoftheEPRIdataforfailureoccurringwithin24hours.DuringSTP scenarioswherespraysinitiate,allspraysaresecuredcloseto6.5hoursinaccord withEOPswithTechnicalSupportCenter(TSC)concurrences(LAREncl.3-4, Ref.[34]).Thetotalmasses(epoxy,alkyd,etc.)ofunquali"edcoatingsenteredinCASAGrandeweremultipliedthroughtheirrespectivetransportlogictreesofLAR Encl.4-3(Figures5.5.85.5.14,pp.169-172).PercentageslistedintheFraction ofDebrisatSumpcolumnofthetransportlogictrees(LAREncl.43,Figures 5.5.85.5.14,pp.169-172)givethefractionsavailableforactivecirculationin thepoolforeachbranch;thesumofthesefractionsisgiveninthebottomright cornerofeachlogicdiagramgivingthetotalactivecirculationfraction(sum:).

Themassofeachunquali"edcoatingmultipliedbyitsrespectivetotalactive circulationfraction(sum:)istheamountthatwasintendedtobeintroduced intothepoolover36hours(seediscussionofErrorReport#4above),butwas insteadintroducedinthe"rsttimestepinadvertently.Allunquali"edcoatings massesactivelyrecirculatinginthepoolarecalculatedtoarriveatthestrainers accordingtothesolutionsofLAREncl.4-3,Eqn.84.Equation84modelsdebris accumulationasacumulativeexponentialcurvede"nedbythetotalECCS"ow

rate.Consistentwithrespectivebranchesinthetransportlogicdiagrams(LAREncl.4-3,Figures5.5.85.5.14,Pgs.169-172),unquali"edcoatingsmasses(not inuppercontainment)addedtothepoolforactivecirculationarecalculated withEquationAbelow.

MLower (Active)=(M total)(Ffail)(Floc)(Frecirc)(EquationA) where:Tuesday1 stMarch,2016:19:32,Page275of393 DRAFTPART2.RAIRESPONSES(ROUND1)

MLower (Active)=massofunquali"edcoatingsnotinuppercontainmentavail-ableforactivecirculation M total=Totalmassquantityofunquali"edcoatingbytype Ffail=Failurefractionofunquali"edcoating Floc=Locationtransport fraction Frecirc=Transportedlocationfraction(activecirculationfraction)Althoughallunquali"edcoatingsnotinuppercontainmentfailat100%

(Ffail=1),theyarestillmultipliedbytheirrespectivelocationandrecircula-tionfractions.Thelocationfractionfortheunquali"edcoatings(notinupper containment)Flocassignsthepercentageofunquali"edcoatingsthattransport tolowercontainmentandthepercentagethattransportstothereactorcavity (LAREncl.4-3,Section5.5).TheactiverecirculationfractionFrecircassigns thepercentageoffaileddebrisfromalocationthatisactivelycirculating.Mass totalsforeachoftheunquali"edcoatingstypesthatareaddedtothepool foractivecirculation(EquationA)areshownbelowinTableAandTableB forlowercontainmentandthereactorcavity,respectively;wheretransportand failurefractionshavebeentakenfromtheunquali"edcoatingsdebristransport logicdiagramsofLAREncl.4-3(Figures5.5.85.5.14,Pgs.169-172)andtotal massestakenfromLAREncl.4-3,Section2.2.10.Althoughallunquali"edcoatingsnotinuppercontainmentfailat100%

(Ffail=1),theyarestillmultipliedbytheirrespectivelocationandrecircula-tionfractions.Thelocationfractionfortheunquali"edcoatings(notinupper containment)Flocassignsthepercentageofunquali"edcoatingsthattransport tolowercontainmentandthepercentagethattransportstothereactorcavity (LAREncl.4-3,Section5.5).TheactiverecirculationfractionFrecircassigns thepercentageoffaileddebrisfromalocationthatisactivelycirculating.Mass totalsforeachoftheunquali"edcoatingstypesthatareaddedtothepool foractivecirculation(EquationA)areshownbelowinTableAandTableB forlowercontainmentandthereactorcavity,respectively;wheretransportand failurefractionshavebeentakenfromtheunquali"edcoatingsdebristransport logicdiagramsofLAREncl.4-3(Figures5.5.85.5.14,Pgs.169-172)andtotal massestakenfromLAREncl.4-3,Section2.2.10.TableA:Activelycirculatingmassofunquali"edcoatingsfoundinlowercontainment CoatingTypeTotalUn-quali"ed Coatings Mass M totalFailureFrac-tion FfailLocationFraction (LowerCon-tainment)

F locTransported

Recircula-tionFraction

FrecircMassAc-tivelyCircu-lating(lbm)

MLower (Active)Unquali"edAlkyd("nes)271100%46%100%125 Unquali"edEpoxy("nes)234100%2%100%5 Unquali"edEpoxy("ne chips)709100%2%41%6 Unquali"edEpoxy(small chips)180100%2%0%0 Unquali"edEpoxy(large chips)391100%2%0%0 Unquali"edEpoxy (curledchips)391100%2%100%8 Unquali"edIOZCoat-ings("nes)369100%17%100%63

REFERENCES:

Tuesday1 stMarch,2016:19:32,Page276of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableB:Activelycirculatingmassofunquali"edcoatingsfoundinthereactorcavity CoatingTypeTotalUn-quali"ed Coatings Mass M totalFailureFrac-tion FfailLocationFraction (LowerCon-tainment)

F locTransported

Recircula-tionFraction

FrecircMassAc-tivelyCircu-lating(lbm)

MLower (Active)Unquali"edAlkyd("nes)271100%0%0%0 Unquali"edEpoxy("nes)234100%83%0%0 Unquali"edEpoxy("ne chips)709100%83%0%0 Unquali"edEpoxy(smallchips)180100%83%0%0 Unquali"edEpoxy(large chips)391100%83%0%0 Unquali"edEpoxy (curledchips)391100%83%0%0 Unquali"edIOZCoat-ings("nes)369100%0%0%01.ElectricPowerResearchInstitute.DesignBasisAccidentTestingofPres-surizedWaterReactorUnquali"edOriginalEquipmentManufacturerCoatings.

FinalReport:September2005.2.3.5.25ESGB,Coatings:Question5 STPResponse:(Item5,Page60)ThevalueofF(t)is6%.Thevalue(6%)forthe0-24hourtimeperiodwaschosenbecauseitrepresentsanoverpredictionofthetimeinwhichallsprays willbesecuredforLBLOCAs.Yes.F(t)isthesameforallunquali"edcoatingtypes Thecumulativemassesofunquali"edcoatingscalculatedbyLAREncl.4-3,Equation28arenottimedependentandrepresenttheamountofeachunqual-i"edcoatingthatwouldenterthepoolover30daysifsprayswereoperating throughtheentireevent.ThisequationanditsresultsarenotusedintheSTP CASAGrandeevaluationbutvalueshavebeenprovidedinTableBbelow.Thetotalmassesofunquali"edcoatingsthatfailedinuppercontainmentduringthe0-24hourtimeperiodwerecalculatedwithEquation27andare providedinTableA.Additionalinformation F(t)wasassignedavalueof6%forallunquali"edcoatingsinuppercon-tainment,andwasappliedasawashdowntransportfractionintheSTPCASA Grandeevaluation(LAREncl.4-3,Pg.157).OthervaluesofF(t)areprovided inTable6ofLAREncl.4-3,reference12(Pg.30),buttheywerenotappliedin theSTPCASAGrandeevaluation(discussedbelow).F(t)valueswerecalculatedfromEPRIdata(i.,Pg.4-5)foundinLAREncl.4-3,reference12(Pg.25).Theunquali"edcoatingsfailuretiminganalysisof LAREncl.4-3,reference12(Pg.25)isbasedonvisualinspectionof"ltersused intheEPRIunquali"edcoatingstesting(i.,Pg.4-3).These"lterswerechanged inuneventimeincrementsduringtheEPRIautoclavetesting,andthe"lters wererankedfrom0to10bythedegreeofdiscoloration(LAREncl.4-3,Ref.

[12],Pg.25)fortheirrespectivetimeincrement.TheresultsoftheanalysisTuesday1 stMarch,2016:19:32,Page277of393 DRAFTPART2.RAIRESPONSES(ROUND1)performedinLAREncl.4-3,reference12(Table5,Pg.27)wereextrapolatedto30dayswithanarti"ciallyforced(normalized)cumulativefailureof100%over alltimeincrements(LAREncl.4-3,Ref.[12],Table6,Pg.30).The6%value (0-24hourtimeincrement)forF(t)wastheonlytime-relatedfailurefraction assignedinCASAGrandeforunquali"edcoatings.TheF(t)value(6%)forthe 0-24hourtimeperiodwasusedbecauseitrepresentsanoverpredictionofthe timeinwhichallsprayswillbesecuredforlargebreaks(LBLOCA)(LAREncl.

Ref.[35]).AnF(t)of6%wasonlyappliedtocoatingsinuppercontainment.For scenarioswherespraysinitiate,allspraysaresecuredcloseto6.5hours(LAR Encl.3-4,Ref.[34]).Thetotalmassofeachunquali"edcoatingintroducedtothepoolforactivecirculationiscalculatedusingthetotalunquali"edcoatingsmassesprovidedin LAREncl.4-3(Section2.2.10)andtheircorrespondingdebristransportlogic diagrams(LAREncl.4-3,Figure5.5.8Figure5.5.14,Pgs.169172).The totalmassintroducedtothepoolforactiverecirculationincludescontributions fromthe24hour6%washdownfractionrepresentingthetime-dependentfailure F(t).Thesetotalmasseswereintendedtobeintroducedtothepoolatuniform rateover36hours;however,acodelevelerror(CASAGrandev1.6Release Notes,ErrorReport#04)forcedadditiontothepoolofall(activelycirculat-ing)materials,includingunquali"edcoatings,atuniformratesduringthe"rst 10minutes.AccumulationofsuspendeddebrisdoesnotbeginuntilECCSrecir-culationbegins.Thetotalmassofeachunquali"edcoatinginuppercontainmentthatfailsinthe"rst24hours,andisavailablefortransport,iscalculatedusingEquation 27below(LAREncl.43,Pg.157).

M i,j (t)=M total: i,j Ffail: i F (t)(Eq27)where: M i,j (t)=Massofunquali"edcoatingsthatfailduringaspeci"ctimeperiod t=Speci"ctimeperiodfollowingthestartoftheaccidentSubscripti=Unqual-i"edcoatingtype(epoxy,IOZ,alkyd,orbakedenamel)Subscriptj=Coating location(uppercontainment,lowercontainment,orreactorcavity)

M total: i,j=Totalmassofunquali"edcoatings Ffail=Totalfailurefraction F (t)=Fractionofcoatingsthatfailduringaspeci"ctimeperiod M i,j: cum=Cumulativemassofunquali"edcoatingsthatfailThelocationandunquali"edcoatingtype-dependentmass(M total: i,j)iscal-culatedastheproduct M total: i,j=M total F upper(EquationA) where, M total=Thetotalmassofaspeci"cunquali"edcoatingtypeincontainment F upper=Thefractionofaspeci"cunquali"edcoatinginuppercontainmentSubstitutingEquationAintoEquation27andevaluatingwithSTP-speci"cinformationprovidestheresultsshownbelowinTableAfortotalfailedunqual-i"edcoatingsmassfromtheuppercontainmentavailabletotransporttothe sump.Theright-handcolumngivesthemassesofunquali"edcoatings(from uppercontainment)thatareinactiverecirculationduringtheCASAGrandeTuesday1 stMarch,2016:19:32,Page278of393 DRAFTPART2.RAIRESPONSES(ROUND1)simulation.Thesevalues(MijofTableA)mustbemultipliedbytheirrespectiverecirculationfractionsto"ndtheunquali"eddebrisamountsthatareactively recirculatinginthepool.TableA:Totalfailedmassesfromuppercontainmentavailabletothesump CoatingTypeTotalUn-quali"ed Coatings Mass(lbm)

M totalFailureFrac-tion FfailUpperCon-tainmentFraction F upperF(t)Imple-mentedasWashdown Fraction F (t)TotalFailed(0-24hours)MassinUp-perContain-ment(lbm)

M i,j (t=24hrs)Unquali"edAlkyd("nes)271100%54%6%8.8 Unquali"edEpoxy("nes)234100%15%6%2.1 Unquali"edEpoxy("ne chips)709100%15%6%6.4 Unquali"edEpoxy(smallchips)180100%15%6%1.6 Unquali"edEpoxy(large chips)391100%15%6%3.5 Unquali"edEpoxy (curledchips)391100%15%6%3.5 Unquali"edIOZCoat-ings("nes)369100%83%6%18.4ThecumulativemassformulationshownbelowinEquation28(LAREncl.4-3,Pg.157)representstheamountofeachunquali"edcoatingthatwouldenter thepoolover30daysifsprayswereoperatingthroughtheentireevent.The resultsofequation28arenotusedintheCASAGrandeevaluation.

M i,j: cum=M i,j F (t)=M total: i,j Ffail: i(Equation28)SubstitutingEquationAintoEquation28givesresultsforthecumulativefailure(TableB)below.TableB:TotalfailedmassesfromuppercontainmentavailabletothesumpCoatingTypeTotalUnquali"edCoatingsMass(lbm)

M totalFailureFraction FfailUpperContainmentFraction F upperCumulativeFailure(0-24hrs)Massin UpperContainment (lbm)M i,j: cumUnquali"edAlkyd

("nes)271100%54%146Unquali"edEpoxy

("nes)234100%15%35Unquali"edEpoxy("nechips)709100%15%106Unquali"edEpoxy(smallchips)180100%15%27Unquali"edEpoxy(largechips)391100%15%59Unquali"edEpoxy(curledchips)391100%15%59Unquali"edIOZCoat-ings("nes)369100%83%306Thecumulativefailedmassesintherighthandcolumn(M i,j: cum)ofTableBgivetheamountsofunquali"edcoatingsthatwouldenterthepoolover30days ifsprayswereoperatingthroughtheentireevent.Thesevalues(M i,j: cum)werenotusedintheSTPCASAGrandeevaluation.Tuesday1 stMarch,2016:19:32,Page279of393 DRAFTPART2.RAIRESPONSES(ROUND1)

REFERENCE:

1.ElectricPowerResearchInstitute.DesignBasisAccidentTestingofPres-surizedWaterReactorUnquali"edOriginalEquipmentManufacturerCoatings.

FinalReport:September2005.2.3.5.26ESGB,Coatings:Question6a STPResponse:(Item6a,Page60)Thegenerictypeofeachunquali"edcoating(i.e.epoxy,alkyd,etc.)isdocu-mentedintheSTPunquali"edcoatingsinventorylog(LAREnclosure4-3,Ref-erence[12]).Thespeci"cproductdescription,however,isunavailableformany unquali"edcoatings.Productdescriptionsarealsounavailableformanyofthe coatingstestedintheEPRIstudy(LAREnclosure5,Reference[3]),theextent ofcomparisonismadetoapplicablegenericcoatingtypesthatareavailable.2.3.5.27ESGB,Coatings:Question6b STPResponse:(Item6b,Page60)Estimatedfailuretimingofunquali"edcoatingswasbasedonvisualanal-ysisof"lterdiscoloration.Itistruethatthecolorsofcoatingstested "lterdiscoloration.However,itisalsoseenfromtheEPRItestingthatalkyds, themostcolorfulcoatingsgroup,experiencedahigheraveragepercentageof detachmentthanothercoatings(LAREnclosure5,Tables3-1,4-2,Pages3-2, 4-5).Becausealkydcoatingsexperiencedhigheraveragefailureoverthe7-day test,theyarealsoassumedtohavethelargestfailurerate.Thisinterpretation ofthedataimpliesthatranking"ltersbydiscoloration(visuallydominatedby heavilypigmentedalkyds)mayconservativelybiasinferredfailuretimingtothe maximumunquali"edcoatingsfailurerateofalkyds.Asingleestimatedfailure ratewasappliedforallupper-containmentunquali"edcoatingstypesintheSTP LAREnclosure4-3analysis.2.3.5.28ESGB,Coatings:Question6c STPResponse:(Item6c,Page61)Becausealkydcoatingshavethegreatestin"uenceonsubjectiveinterpreta-tionofphotographs(byvirtueofdistinctivecoloration),andhavethehighest averagesubstratedetachment,inferredfailureratescanonlybebiasedtowards themaximumunquali"edcoatingsfailurerateofalkyds.Seediscussioninre-sponsetoESGBRAI6b.Analternativejusti"cationofthe6%failurefractionwithintherelevantmissiontimeproceedsasoutlinedinFigure1below.TheEPRIstudy(LAREnclosure5,Reference[3]),statesWithregardtotimingofthecoatingfailures,the"ltersdonotdemonstrateade"nitivetimeof failure,howeverinsubjectiveterms,itappearsthatmuchofthefailureoccurred inthe24-to48-hourtimeframe.Althoughthereisnode"nitivede"nitionfor thesubjectiveobservation"muchofthefailure,"Figure1showsthreedt scenariosbuiltonavariationintheamountofunquali"edcoatingsthatare estimatedtodetachbetween24and48hours.Thegreencurvedisplaysanend-ingdetachmentpercentageequaltothetotalaveragedetachmentofallSTP analyzedcoatings(epoxy,IOZ,alkyd)overthe7-dayEPRItesting(27%).This curvesetsthemaximumpercentageoffailedunquali"edcoatingsover7daystoTuesday1 stMarch,2016:19:32,Page280of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure1:FailurePercentageasaFunctionofTime27%andassumesthat21%ofthetotalfailure(from6%to27%total)occurswithinthe24to48-hourperiod.Ifmorethan21%ofthecoatingsfailinthe24-to48-hourtimeperiod,thepercentageofcoatingsthatfailat24hourswillbe shiftedtolessthantheSTPassumed6%failure.Ifthede"nitionofmajority failurewithin24to48hoursischangedto55%oftheavailablefailure,then theassumedfailureat24hrswoulddoubleto12%(linenotshown).Paramet-ricevaluationshaveshownthattotalriskisinsensitivetothisrangeofadded

particulate.If100%failureisarti"ciallyassumedoverthe7-dayperiodandassumethatmuchofthefailurecanbede"nedas89%(from6%to95%)and55%(from 40%to95%),theresultsaretheredandbluecurvesofFigure1,respectively.

Bothcurvesassumea5%residualfailureafter48hours.Itcanbeseenthatif 89%ofthefailureisassumedtooccurbetween24-and48hours,6%willhave tofailbefore24hours.Howeverifitispostulatedthat55%(oneinterpretation ofmajority)mustfailinthe24-to48-hourtimeframe(bluecurve),thefailure before24hourswouldbe40%,whichwouldcontradicttheobservedtotalaverage detachmentof27%.2.3.5.29ESGB,Coatings:Question7 STPResponse:(Item7,Page61)TheSTPcoatingsarecontrolledunderSTPProcedure0PMP06-ZD-0001PaintsandCoatings.Theprogramincludesapplicationrequirements,visual examination,anddocumentationofallconcreteandsteel-coatedsurfacesinthe containmentbuildingtoidentifyanytypeofcoatingdegradationsuchas"aking, peeling,blistering,delamination,rustingandmechanicaldamage.Anyareasof degradationaredocumentedandevaluatedforseverityanddeterminedtobe either:repairedduringthecurrentoutage,repairedinthenextavailableoutage, orcontinuedtobemonitoredandre-evaluatedduringthenextavailableoutage.

[Ref:ASTMD5163-08,para.10.2andpara.11.1.2]TheCoatingAssessmentInspectionincludesavisualexaminationofallac-Tuesday1 stMarch,2016:19:32,Page281of393 DRAFTPART2.RAIRESPONSES(ROUND1)cessibleServiceLevel1coatingsinsidecontainmentincludingthesteelcontain-mentliner,structuralsteel,supports,penetrations,uninsulatedequipment,and concretewallsand"oorsreceivingepoxysurfacesystems.Thisincludesareas nearsumpsassociatedwiththeemergencycorecoolingsystem.TheCoating AssessmentInspectiondoesnotincludecoatingofsurfacesthatareinsulatedor otherwiseenclosedinnormalservice,andconcretereceivinganon-"lmforming clearsealercoatonly.[Ref:ASTMD5163-08,para.10.1]TheCoatingAssessmentInspectionofServiceLevel1coatingsisconductedateachrefuelingoutagebyproperlyquali"edcoatinginspectors;thetimeperiod betweenoutagesisapproximately18months.TheServiceLevel1CoatingsAs-sessmentInspectionisconductedbySTPsCoatingEngineerandCoatingPlan-ner.TheCoatingEngineermeetstheeducational,professionalachievementsand nuclearcoatingsexperiencequali"cationcriteriaforquali"cationasaNuclear CoatingsSpecialistinaccordancewithASTMD7108-05.TheCoatingEngineer istheresponsibleEngineerinchargeoftheSafety-Relatedcoatingsprogram.

TheCoatingsPlannerisacerti"edNACELevelIIIInspectorandmeetsthe educational,professionalachievementsandnuclearcoatingsexperiencequali"-

cationcriteriaforquali"cationasaNuclearCoatingsSpecialistinaccordance withASTMD7108-05.[Ref.ASTMD5163-08,para.6.1andpara9.1].PriortotheCoatingAssessmentInspection,coatinginspectorsreviewthetwopreviouscoatingassessmentreports.Fromtheprevioustwocoatingassess-mentreports,areasidenti"edasbeingmonitoredandre-evaluatedinthenext availableoutagearenotedandaddedtothelocationmapsforthecurrentCoat-ingsAssessmentInspection.[Ref:ASTMD5163-08,para.7.2]ThecoatinginspectorsbringintotheReactorContainmentBuilding(RCB)theproperinstrumentsandequipmentneededforinspection,including,but notlimitedto:locationmaps,"ashlights,markerpen,measuringtape,feeler gauge,binocularsandcamera.Thelocationmapsdividingthereactorcontain-mentbuildingintotwenty-four(24)identi"able"oorplansarelabeledwith pertinentelevation,azimuthreferences,structuralfeaturesandcomponents.All areasofdegradedcoatingsidenti"edduringtheCoatingsAssessmentInspection arerecordedonthelocationmaps.Allareasthatcannotbeinspectedduring theCoatingsAssessmentInspectionandthespeci"creasonwhytheinspection cannotbeconductedareidenti"edonthelocationmaps.[Ref:ASTMD5163-08, para.7.2,para.10.1.3andpara.10.5]Physicaltestsareperformedonanas-needbasisasdeterminedbythecoat-ingsinspectors.Blisteringofallsizes,"aking,peeling,anddelaminationare consideredrejectableconditions.Thesourceandextentofanyrustingisevalu-atedduringthevisualinspectionbythecoatingsinspectors.Cracksover30mils areevaluatedbyEngineeringandallcrackslessthan30milsarearejectablecon-ditionanddocumentedinaccordancewithPGP03ZX0002,ConditionReporting Process.[Ref:ASTMD5163-08,para.10.2]TheCoatingsAssessmentReporthasbeenevaluatedandapprovedbythecoatingsinspectorswhocollaborateintheevaluationofdegradedcoatingsand determinationofrecommendations.TheCoatingsEngineerpreparestheCoat-ingsAssessmentReportandtheCerti"edNACELevelIIICoatingsPlanner preparesworkordersfortherepairofdegradedcoatingsinaccordancewith PGP03ZX0002,ConditionReportingProcess.[Ref:ASTMD5163-08,para.Tuesday1 stMarch,2016:19:32,Page282of393 DRAFTPART2.RAIRESPONSES(ROUND1) 11.1]2.3.5.30SNPB,Question4 STPResponse:(Item4,Page65)ThetimingforboricacidprecipitationisgiveninSTPNOCCalculationNC-7136(Reference1).Thecalculationsummaryfollowsbelow:

OBJECTIVE Thiscalculationdeterminestheeoftheincreaseindeliverablewa-tervolumefromtheRefuelingWaterStorageTank(RWST)onthehotleg switchovertimefollowingalargebreaklossofcoolantaccident(LBLOCA).Hot legswitchover(HLSO)isrequiredtoensurethatboronprecipitationdoesnot occurinthereactorcore.1.4%PowerUprate:TheNRCapproveda1.4%increaseinthereactorcorepowerlevelfrom3,800 MWtto3,853MWt.Theeofthisincreaseisdetermined.Replacementsteamgenerators:Delta-94steamgeneratorswereinstalled.Theeofthischangeisdetermined.INTENDEDUSEOFRESULTS ThiscalculationsupportstheHLSOtimeusedinemergencyoperatingpro-cedure0POP05-EO-EOI0.

SUMMARY

OFRESULTS TheincreaseintheRWSTinjectedvolumehasnegligibleontheHLSOtimefollowingaLBLOCA.IftheRCSvolumeisataboronconcentrationof2830 ppm,themixedsumpboronconcentrationisonlyabout3.3ppmhigherthan previouslyanalyzedwhichiswellwithinmeasurementaccuracy.IftheRCS boronconcentrationisincreasedto3500ppminMode3onehourafterexiting Modes1or2,thenanincreaseinRWSTinjectedvolumeactsasadilutionsource whichisboundedbytheanalysisdocumentedinST-UB-HL-1680previously performed.Therefore,theHLSOtimeof6.0hoursisvalid.However,toensure adequatemarginfortimetoHLSOismaintained,theplantemergencyoperating procedureOPOP05-EO-EOIOspecifyaHLSOtimeof5.5hours.1.4%PowerUprateResultsThecalculationisindependentofreactorpowerlevel(to3853MWt),therefore thepowerupratewillnottheresults.

Delta-94SteamGeneratorResults TheexistinganalysisofrecordisapplicabletoUnits1and2.INTRODUCTION/BACKGROUND Aspartoftherequirementtomaintainthecorecoolablegeometryinthelongterm,Section6.3ofNUREG-0800requiredthatstepsbetakentoprecludetheprecipitationofboroninthevessel.Intheeventofacoldlegbreak,while theECCSisalignedtotheRCScoldlegs,boronconcentrationinthecoreregion increasesduetobofthewater.Toprecludeboronprecipitation,onetrain ofSlisrealignedtotheRCShotlegsatthehotlegswitchover(HLSO)time.ThedesignbasisthatrequiresHLSOisestablishedby10CFR50.46whichrequiresthatthereactorcoremaintainlongtermcoolingafteraLOCAevent.

Duringadouble-endedbreakofthecoldleg,mostofthesafetyinjection"ow entersthecoldleg(s),goesintothedowncomerregionofthereactor vesselandoutthebreakinthebrokencoldleg.Thesafetyinjection"owthatTuesday1 stMarch,2016:19:32,Page283of393 DRAFTPART2.RAIRESPONSES(ROUND1)entersthereactorcoreforthepurposesofcoolingisattributabletothemano-metricpressurebetweenthedowncomerandthereactorvessel.Thisresultsin thesafetyinjection"owboilinginthereactorcoreandleavingassteam.The boronconcentrationofthewaterinthereactorvesselincreasesuntilsuchapoint thatboronprecipitationoccurs.Whenboronprecipitationoccurs,thefuelrods canbecomecoatedandimpedelongtermcoolingofthefuel.Boronprecipita-tionisassumedtooccurwhentheboronconcentrationreaches23.5wt%(41,000 ppm),whichis4wt%lessthantheboronsolubilitylimitofasolutionat2120F.The23.5wt%isanNRCimposedlimit.TheRefuelingWaterStorageTank(RWST),Slaccumulators,andtheECCSpipingaresourcesofthehighestconcentrationofboratedwater.Anincreasein thevolumeofanyoneofthesesourceswillincreasetheboronconcentrationof themixedsumpwaterincontainment,andtherefore,decreasethetimetoboron precipitationinthecore.TheRCS,whichisatalowerboronconcentration, servesasadilutionsourceforthemixedsumpwater.Therefore,anincrease intheprimarysideRCSvolumewillleadtoanincreaseinthetimetoboron

precipitation.AspartofthesetpointreviewethecalculationofthetotaldeliverableRWSTwatervolumehasbeenrevised.Thenewrevisiondocuments(Ref.5)the maximuminjectionvolumeis541,000gallons.Thisnewvalueisgreaterthanthe 453,400gallonsassumedinthesafetyanalysisforthetimetoHLSOfollowing aLOCAevent.SinceanincreaseintheRWSTdeliverablewatervolumewill increasethemixedsumpboronconcentration,theHLSOtimeisexpectedto

decrease.WestinghousehasrevisedtheirmethodologyforcalculatingthetimetoHLSOtocorrectanerrorintheboronconcentrationdensityterm.Thiscor-rectionresultedinaHLSOtimethatdecreasedfrom6.5to6.0hours.Thiswas recommendedbyWestinghousetobeincorporatedintheplantemergencyop-eratingprocedures.However,pertheReportabilityReviewforCR98-5868and USQE98-0032,theHLSOtimewasreducedto5.5hourstoensureboronpre-cipitationwillnotoccurandre"ectedassuchinprocedure0POP05-EO-EO10.InsupportofthelicensingapplicationfortheDelta-94steamgeneratorsandthe1.4%uprate,varioussafetyanalysesarerequiredtobeperformedforthe newsteamgeneratorsorreviewedtocon"rmthecurrentapplicabilityofthe mostrecentanalysis.Thisreviewshowsthatthereisnoeontheresultsof

NC-7136.RESULTS/CONCLUSION TheincreaseintheRWSTinjectedvolumehasnegligibleontheHLSOtimefollowingaLBLOCA.IftheRCSvolumeisataboronconcentrationof 2830ppm,themixedsumpboronconcentrationisonlyabout3.3ppmhigher thanpreviouslyanalyzedwhichiswellwithinmeasurementaccuracy.IftheRCS boronconcentrationisincreasedto3500ppminMode3onehouralterexiting Modes1or2,thenanincreaseinRWSTinjectedvolumeactsasadilutionsource whichisboundedbytheanalysisdocumentedinST-UB-HL-1680previously performed.Therefore,theHLSOtimeof6.0hoursisvalid.However,toensure adequatemarginfortimetoHLSOismaintained,theplantemergencyoperating proceduresOPOP05-EO-EO10hasbeenchangedtospecifyaHLSOtimeof5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.ThisisdocumentedintheReportabilityReviewforCR98-5868.Tuesday1 stMarch,2016:19:32,Page284of393 DRAFTPART2.RAIRESPONSES(ROUND1)ForMode3,theHLSOtimeanalysiswithanincreasedRCSboronconcen-trationto3500ppmfollowingaonehourwaitalterexitingModes1or2is boundedbytheMode1analysisasdocumentedinST-UB-HL-1680.

Reference:

1.STPNOCCalculationNC-7136Rev.1HotLegSwitchoverTimeFollow-ingLOCA2.3.6SSIBResponses 2.3.6.1SSIB,DebrisCharacteristics:Question3 STPResponse:(Item3,Page67)No,Table2.2.21ofLAREnclosure4-3isnotdirectlyimplementedintothehead-losscorrelation.Table2.2.21ofLAREnclosure4-3liststhematerial propertiesofdebris.AsdescribedintheLAREnclosure4-3,Page178,some modi"cationsweremadetothevaluesprovidedinSection2.2.16.Tables5.6.1 and5.6.2presentthematerialpropertiesasimplementedintothehead-loss correlation.Table2.2.21andTables5.6.1and5.6.2arenotidenticaldueto assumptionsrelatedtothehead-losscorrelationandmaterialdebrissizeranges.

Forexample,allLDFGwasassumedtobe"nesintheheadlosscorrelation, whichisnotedasonebetweenthetables.Theeofdebrissizeon risk,selectionofdebrissizeforthehead-losscorrelation,anduncertaintyofthe sizedistributionareexaminedintheresponsetoSSIBRAI24.Uncertaintyin materialpropertiesisaccountedforinthefactorof5uncertaintyboundapplied toallhead-losspredictions.2.3.6.2SSIB,Transport:Question4 STPResponse:(Item4,Page67)Thesteamgeneratorcompartmenttransportfractionswerechosenforthefollowingreasons.

• TransportfractionscalculatedfromtheSteamGeneratorCompartmentarereasonablyconservativeandmaximizetransportforallconsidered breaksexceptthoseintheBelowtheSteamGeneratorCompartmentlo-

cation.*TheSteamGeneratorCompartmenthasamuchlargerTotalPercentageofLDFGwhencomparedtotheothercompartments.

• TheSteamGeneratorCompartmenthasthesecondgreatestCongestiontothePressurizerCompartmentwhichhasnon-conservativetotaltransport

fractions.Thisresponsehasthreesub-parts,whichconsistofanexplanationforas-sumption6.h.iofLAREncl.4-3,Table2.2.22ofLAREncl.4-3,andtheimple-mentationofSGcompartmenttransportfraction.Assumption6.h.iofLAREncl.4-3Assumption6.h.iofLAREncl.4-3states:

I.WorstcasevalueswereselectedfromthetransportfractionrangesforsteamgeneratorcompartmentblowdownandwashdownFigure1illustratesthatthevaluesusedtodevelopoveralltransportfractionlogictreeswerethemaximumvaluesoftherangesinthetransportanalysisandTuesday1 stMarch,2016:19:32,Page285of393 DRAFTPART2.RAIRESPONSES(ROUND1)wereselectedinawayastoresultinthemaximumoveralltransporttothesumpstrainers,exceptfortheerrorasnotedintheresponsetoSSIBRAI7E.InFigure1,Table2.2.22andTable2.2.23areextractedfromLAREncl.4-3.Figure5.12.2istakenfromthedebristransportcalculation(LAREncl.

4-3,Ref.[23]).(Reference23inLAREncl.4-3hasbeenrevisedtoRevision3 (1).However,theprocessillustratedinFigure1isthesameinrevision3asin revision2.)Figure1.IllustrationofProcessDescribedinItemIofAssumption6.hTable2.2.22ofLAREncl.4-3LAREncl.4-3,Table2.2.22summarizestransportfractionsaccordingtobreaklocationforonlytheblowdownportionofoveralltransport.Theother processesthatcontributetooveralltransportarewashdown,pool"ll,andrecir-culation,whosecontributionsarenotre"ectedinTable2.2.22.ImplementationoftheSGCompartmentTransportFractionTheoveralltransportfractionscomputedinrevision3ofthedebristransportcalculation(1)aredisplayedinTable1.Foreachdebriscategorythemaximum valuesarehighlightedinthetable.Thetotaltransportfractionforthesteamgeneratorcompartmentisconser-vativeforindividualLDFGandlatentdebrisbutisnon-conservativeforsmallandlargeLDFG.Asinglebreaklocationstransportfractionswereselectedtomodeltrans-portforallofthebreaksCASAsimulates.Ifbelowthesteamgeneratorcom-partmenttransportfractions(whichgeneratethemostconservativesmalltotal LDFGtransportfraction)wereimplemented,themodelwouldbeaccuratefor thebreaksbelowthesteamgeneratorcompartment,butwouldoverpredicttheTuesday1 stMarch,2016:19:32,Page286of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableA:OverallDebrisTransportFractionsBreakLocationRegionIndividualLDFGSmallLDFGLargeLDFGLatentSGCompartment99%42%1%95%BelowSGCompartment99%60%7%95%

PressurizerCompartment97%31%1%91%

PressurizerSurgeLine97%30%1%91%

RHRCompartment97%30%2%91%

Annulus97%33%8%91%transportforeveryotherbreak.Thesteamgeneratortransportfractionswere implementedbecausetheyarereasonablyconservative.Themodelisaccurate forthebreaksinthesteamgeneratorcompartment,underpredictstheLDFG transportforbreaksbelowthesteamgeneratorcompartment,andoverpredicts theLDFGtransportforallotherbreaks.Table2displaysthetotalvolumeandpercentageofLDFGinthebreaklocationregions.LDFGcongestion(theratioofinsulationvolumetothebreak locationregionvolume)isameasureofthepotentialamountofLDFGthat couldbedestroyedfromasinglebreak.ThismetricisalsodisplayedinTable2; thelargestpercentagesarehighlighted.TableB:InsulationintheBreakLocationRegionsBreakLocation RegionLDFGVol.(ft 3)PercentageoftotalLDFG

(%)RegionVol-ume(ft 3)LDFGConges-tion(%)SGCompartment5,52955201,5522.7 BelowSGCom-partment2783100,7320.3PressurizerCom-partment553610,9335.1PressurizerSurge Line5013,013 1 1.7RHRCompart-ment411431,6981.3Annulus3,16632637,7080.5 2Reference[i]N/ALAREncl.4-3,Ref.[23]

N/A 1ThevolumeofthepressurizersurgelineregionwasnotstatedinLAREncl.4-3Ref.[23];thepressurizersurgelineregionvolumewasincludedinthevolume oftheannulusregion.Thevolumeofthepressurizersurgelineregionwas determinedfromtheCADModelSummary(2).

2Theannulusregionvolumewasdeterminedbyreducingtheannulusregion volume(LAREncl.4-3,Ref.[23])bythepressurizersurgelineregionvolume.ThevaluesinTable2showtheSteamGeneratorCompartmenthastheTuesday1 stMarch,2016:19:32,Page287of393 DRAFTPART2.RAIRESPONSES(ROUND1)largestpercentageofLDFG,rangingfromapproximately2to50timesgreaterthanalltheotherlocations.TheSteamGeneratorCompartmenthasthesecond greatestcongestion.ThecongestionofthePressurizerCompartmentisapprox-imatelytwiceasmuchoftheSteamGeneratorCompartment.However,the SteamGeneratorcompartmenthas10timesmoreLDFGthanthePressurizer Compartment.

References 1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.ALION-SUM-WEST-2916-01.CADModelSummary:SouthTexasRe-actorBuildingCADModelforUseinGSI-191Analyses.Revision4.5/22/2014.2.3.6.3SSIB,Transport:Question6a STPResponse:(Item6a,Page67)Thecapturemetricsareadjustedbyaratioofcoveredareatototalareatoaccountforsituationswheregratingdoesnotfullyspanthetransportpathway, asdescribedinthesteamgeneratorcompartmentblowdownsection(LAREncl.

4-3,Ref.[23],Pg.39).Revision3ofthedebristransportcalculationalsoadheres tothismethodology(1,Pg.47).

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCalculation.Revision3.6/10/2014.2.3.6.4SSIB,Transport:Question6b STPResponse:(Item6b,Page67)Thecomputationalmethodologyforblowdowndidnotalwaysaccountfordepletionofdebrisduetocaptureonupstreamobjects.Anexampleofthisis theequationonpage38ofLAREncl.5,whichispresentedbelow.

F BD=V upper V total(1.0F misc)(1.0F 90turns Nturns)x(1.0Fgrating Ngratings), (EQ-1)where: F BD=fractionofdebrisblowntouppercontainment, V upper=volumeofuppercontainment, V total=totalvolumeincontainment, F misc=fractionofde-bristrappedbymiscellaneousstructures, F 90turns=fractionofdebristrappedbychangesin"owdirection, Nturns=numberofturnsorchangesin"owdirec-tiondebriswouldpassthrough, Fgrating=fractionofdebristrappedbygrating, Ngratings=numberofgratingsdebriswouldpassthrough.

If Nturns or Ngratingsisgreaterthan1(asisthecasefornumerousbreaksinItem5.a.2ofLAREncl.5)themodelwillnotproperlyaccountfordepletion onupstreamobjects.However,Reference23ofLAR.Encl.4-3hasbeenrevisedtoRevision3whichcorrectlyaccountsfordepletionofdebrisduetocaptureonupstreamobjects.

ThemethodologyusedfortheblowdownphaseisbasedupontheequationbelowTuesday1 stMarch,2016:19:32,Page288of393 DRAFTPART2.RAIRESPONSES(ROUND1)inthenewrevision(1,Pg.47):

FUC/LCbd=VUC/LC V total(1.0F misc)(1.0F 90turns)Nturnsxni=0{1.0Fgrating (i)Agratings (i)}, (EQ-2)where: FUC/LCbd=fractionofdebrisblowntoupper/lowercontainment, VUC/LC=volumeofupper/lowercontainment, V total=totalvolumeincontainment, F misc=fractionofdebristrappedbymiscellaneousstructures, F 90turns=fractionofdebristrappedbychangesin"owdirection, Nturns=numberofturnsorchangesin"owdirectiondebriswouldpass through, Fgrating (i)=fractionofdebristrappedbyi-thgrating, Agratings (i)=ratioofi-thgratingareaversustotalblowdownarea(rangefrom0-1), n=Ngratings=totalnumberofgratingsthroughwhichdebriswouldpass.Sincetheoverallamountsbywhichdebrisisaccumulatedonthetobjects,e.g.,grating,miscellaneousstructures,etc.,isdeterminedbyaproduct ofthefactors,thecomputationalmethodologyaccountsfordepletionofdebris asitiscapturedonupstreamobjects.Forexample,iftheonlymechanismof debriscapturewasmiscellaneousstructures,Equation1wouldyield:

FUC/LCbd=VUC/LC V total(1.0F misc)Iffurtherupstreamdebriscaptureoccursfrom90turns,itscapturefactor (1.00F 90turns)Nturnswouldbeappliedtoanalreadyreduced F BDquantitybasedupontheupstreamofmiscellaneousstructures;notontheentire debrisquantity.Likewise,iftheadditionalofgratingsisconsidered,its ni=0{1.0Fgrating (i)Agratings (i)},isappliedtoadebrisquantitythathasalreadybeendepletedbytheeofmiscellaneousstructuresand90turns.Similarly,duringthewashdowntransportphase,theofmultiplegrat-ingsistakenintoaccountwiththeimplementationof Fwdown=F cs F WG (1F AG)(Ngratings1)(LAREncl.4-3,Ref.[23],Equation22andi,Equation24),whereagain,eachsuccessiveholdupisappliedtoaquantitythathasalreadybeendecreased.Therefore,thenewcomputationalmethodologyaccountsfordepletionofdebrisasitiscapturedonupstreamobjectsbyapplyingtheofthe n thmechanismtoanalreadydepletedquantityfromthe1 stto(n1)thmechanism.Tuesday1 stMarch,2016:19:32,Page289of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableB.1displaysthetotaltransportfractionsforbothrevisionsofthede-bristransportcalculations(LAREncl.4-3,Ref.[23]and1).Transportfractions thatchangedinrevision3arehighlighted.SmallandlargeLDFGweretheonly debrisclassi"cationswhosetransportfractionsresultedindtvaluesinre-vision3.ThediscrepancyhasbeenenteredintheSTPcorrectiveactionprogram fortrackingforcorrectioninfuturesubmittals.TableB.1:TotalDebrisTransportFractionsSmallLDFGLargeLDFGBreakLocationRegionRev2Rev3Rev2Rev3SGCompartment37%42%1%1%BelowSGCompartment59%60%7%7%

PressurizerCompartment30%31%8%1%

PressurizerSurgeLine62%30%7%1%

RHRCompartment20%30%4%2%

Annulus27%33%1%8%ACASAGrandeparameterstudywasperformedwherethedebristrans-portfractionsweremodi"edtotheRevision3SGCompartmentvalues.This changeresultedinatotaldecreaseof10%.ThevesselACDFdecreased by25%whilethesumpCDFincreasedby9%.Thecounterintuitiveresult,a decreaseintotalwhentheamountofdebrisreachingthestrainerwas increased,isattributedtocompetingphenomena.Byincreasingdebristransport fractions,greaterinitialtransportcausesthe"ltrationofthedebris bedtoincrease,whichinturnallowslessdebristopenetratethestrainerresult-inginsigni"cantlylowerin-vesselCDF.Conversely,theadditionaldebrisat thestrainercausesanincreaseinheadlossandsump-relatedHowever, thecompetingphenomenaweredominatedbythe"ltrationandre-ductionofin-vesselCDF.SimilarinstancesweredocumentedinScenarios1 and2ofpreviousparameterstudies(2,AppendixA)whereadecreaseinlatent "berresultedinanincreaseandanincreaseinlatent"berresultedina decreaseof

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.5SSIB,Transport:Question6c STPResponse:(Item6c,Page67)Reference23ofLAREncl.4-3included90turnsthatwerenotwellrepre-sentedbytheDDTS.However,Reference23ofLAREncl.4-3wasrevisedto Revision3(1)whichonlyconsidered90turnscomparabletotheDDTStestset-upandexpectedresultantdebrisentrapmentpatternasdescribedbelow.Tuesday1 stMarch,2016:19:32,Page290of393 DRAFTPART2.RAIRESPONSES(ROUND1)AreviewofNUREG/CR-6369,DrywellDebrisTransportStudy(DDTS),showsthatthe90bendinthetestset-upwasnotdesignedtosimulateanyspeci"cfeatureofaBWR;the90bendsimplysimulatedaconditionwheredebris-ladenblowdown"owwasforcedtochangeitstrajectoryby90(0).ThesubsequentthreestatementsarequotesfromtheDDTS.Thedebriswasthencarriedbytheair"owover20-ftlongstructuralcongestion,a90bend,andaMarkIvententrance,allofwhichwerepre-wetfedbywarmwatertosimulatesurfacewetnessIn addition,thedebristransportpathwaypassedthrougha900bend.

Thediameterofthetestchamberwasapproximately10ftandthe totaltransportpathlengthwasapproximately70ft....makea900 bendwherethechamberwallhadbeenwettedbymistdriftingwith theslightairdraftthroughthechambers.Asubstantialamountof debriswasdepositedatthisbendandthisdepositionexpressedasa capturefractionisshowninFigure3-35asafunctionofthedebris passingthroughthecollartotheauxiliarychamberintermofmass "uxbasedonthecross-sectionalareaofthechambers,notthecollar.

Themeanvalueforthewettestswas17%.Notethatthecross-sectionalareaofthecollarwasabout60%ofthemainchamberarea andthatthemeancapturefractionbasedonthecollarcross-sectional areawouldbeabout28%.Hence,intheabsenceofanyotherfactors,thetestset-upandresultingdebrisentrapmentassociatedwiththe900bendisequallyapplicabletoaBWR,PWR orothersimilarindustrialfacility.Applicationofthetransportreductionfactorsassociatedwitha90bendinthetransportcalculationwasdonewithconsiderationoftheDDTStestset-up andexpectedresultingdebrisentrapmentpattern.Forexample,blowdownuptouppercontainmentfromeitheraSteamGen-eratorcompartmentbreak,orabreakinpipingintheannulusoutsidetheSec-ondaryShieldWallwouldresultinsomeamountofchangeintrajectoryfrom vertical.Howeversuch"owpathswerenotconsidered900bendsbecausethe changeintrajectorywasjudgedtobelessacutethanthatintheDDTStest set-upandwouldnotresultinthetypeofdebrisaccumulationillustratedin Figure3-25Depositioninauxiliarytankatbend(TestH2)oftheDDTSwhich isdisplayedbelow.Tuesday1 stMarch,2016:19:32,Page291of393 DRAFTPART2.RAIRESPONSES(ROUND1)Conversely,reliefofcompartmentpressurizationthroughgratedopeningincornersof"oors,which(a)requiredanacute90trajectorychange,and(b)whichwouldleadtoadebrisdepositionpatternonthewallatthevertexof

90bendwhichwouldbesimilartotheoneillustratedinDDTSFigure3-25,wereconsideredtohavedebrisentrapmentsimilartothatdescribedinthe

DDTS.Compartmentsthatforcedtheblowdownjettogothrougha180hairpinturn,suchastheaccesswaystoRHRCompartments,wheredebrisentrapment patternssimilartotheoneillustratedinDDTSFigure3-25wouldbeformed inoneormorecorners,andwhichclearlyhadacutetrajectorychanges,were consideredtohavedebrisentrapmentsimilartothatdescribedintheDDTS.TableClsummarizesthepositionsintheSTPcontainmentatwhich90turnswereconsideredtoproduceadebrisentrapmentpatternsimilartotheonesob-servedintheDDTS(1).Insummary,the90bendintheDDTStestset-upisequallyrepresentativeofaBWR,PWRorothersimilarindustrialfacility.Thedeterminationofthe applicabilityofDDTStest90bendentrapmentresultswasbasedupontheexpecteddebrisdepositionpatterninSTP90bendlocationsbeingsimilartothatshownintheDDTS.TableC.2displaysthetotaltransportfractionsforbothrevisionsofthedebristransportcalculations.Transportfractionsthatchangedinrevision3are highlighted.SmallandlargeLDFGweretheonlydebrisclassi"cationswhose transportfractionsweremodi"edinrevision3.Insummary,the90bendintheDDTStestset-upisequallyrepresentativeofaBWR,PWRorothersimilarindustrialfacility.Thedeterminationofthe applicabilityofDDTStest900bendentrapmentresultswasbaseduponthe expecteddebrisdepositionpatterninSTP900bendlocationsbeingsimilarto thatshownintheDDTS.ChangestototaldebristransportfractionsarediscussedintheresponsetoSSIBRAI6b,above.

References:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10//2014.Tuesday1 stMarch,2016:19:32,Page292of393 DRAFTPART2.RAIRESPONSES(ROUND1)TableC.1: 90TurnPositionsintheSTPContainmentBreakLocationFlowpathto:DTCalcEqua-tionNumbersDiscussionof90bendsSteamGeneratorCompartmentsUpperContainment2and3No90bendswereconsideredSteamGeneratorCompartmentsSumpElevation4and5One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating; the90bendisformedby"oor/wallintersection.ReactorCavityUpperContainment2and3No90bendswereconsideredReactorCavitySumpElevation4and5One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating; the90bendisformedby"oor/wallintersection.BelowtheSteamGeneratorCom-partmentFloorUpperContainment6and7One90bendwasconsideredtomodelthechangein"owpathfromthehorizontaltodownwardtrajectorythroughgrating;the90bendisformedby"oor/wallintersection.BelowtheSteamGeneratorCom-partmentFloorSumpElevationN/ANo90bendswereconsideredPressurizerCom-partmentUpperContainment8and9One90bendmodeledtheturntoexittheopeningsatthetopofthePressurizerCompartment;the90bendisformedby"oor/wallintersection.PressurizerCom-partmentSumpElevation10and11One90bendmodeledtheturntoexittheopeningsatthebottomofthePressurizerCompartmentenroutetogratings;the90bendisformedby"oor/wallintersection.PressurizerSurge LineUpperContainment12and13Two90bendmodeledtheexitatthebottomofthePressur-izerCompartmentenroutetogratings;the90bendisformedby"oor/wallintersection.PressurizerSurge LineSumpElevation14and15No90bendswereconsideredRHRCompart-mentsUpperContainment16and17Two90turnsarerequiredtoexitthecompartments(whichelyisa180hairpinturn);the90bendisformedbywalls/wallsintersectionsRHRCompart-mentsSumpElevation18and19Two90turnsarerequiredtoexitthecompartments(whichelyisa180hairpinturn);the90bendisformedbywalls/wallsintersections.AnnulusUpperContainment20and21No90bendswereconsideredAnnulusSumpElevation22and23No90bendswereconsidered[1]DTreferstoRevision3ofReference23ofLAREncl.4-3(1)TableC.2:TotalDebrisTransportFractionsSmallLDFGLargeLDFGBreakLocationRegionRev2Rev3Rev2Rev3SGCompartment37%42%1%1%BelowSGCompartment59%60%7%7%

PressurizerCompartment30%31%8%1%

PressurizerSurgeLine62%30%7%1%

RHRCompartment20%30%4%2%

Annulus27%33%1%8%2.NUREG/CR-6369,Volume2.DrywellDebrisTransportStudy:Experi-mentalWork.September1999.3.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.6SSIB,Transport:Question6d STPResponse:(Item6d,Page67)Speci"climitshavenotbeenplacedonthemassofdebristhatiscomputedtobecaughtonstructures.However,afeasibilitycheckhasbeenperformedand isdiscussedbelow.Thefeasibilitycheckfocusedonestimatingthemaximum crediblequantitiesofLowDensityFiberglass(LDFG)debristhatisconsideredTuesday1 stMarch,2016:19:32,Page293of393 DRAFTPART2.RAIRESPONSES(ROUND1)tobecaughtonstructuresandcomparingthesequantitieswiththequantitiesthatwereobservedintheDDTS.Resultsshowedthatthequantityofdebris computedtobehelduponSTPstructureswaslessthanthoseobservedinthe DDTStestprogram,whichcon"rmsthatDDTStestresultsareapplicableto STPconditions.Thefeasibilitycheckconsistsofa.DeterminingthemaximumquantitiesofLDFGgeneratedforcasesthatresultedinsuccessfulECCSoperationandhadprobabilitiesofoccurrence greaterthan1.0E-15,Itwasdeterminedthat100cubicfeetofLDFGwasthemaximumtotalSTPLDFGquantityforcasesthatresultedinsuccessfulECCSopera-tionandhadprobabilitiesofoccurrencegreaterthan1.0E-15.Casesthat resultedinfailurewerenotofinterestbecauseifalimitonastructure allowedmoredebristobypass,thecasewouldstillresultinfailure.b.EstimatingthetotalquantitiesofLDFGdebriscomputedtobehelduponSTPStructuresand90bendsduringblowdownphase,c.EstimatingtheportionofthetotalquantitiesofSTPLDFGdebriscom-putedtobeheldupthataresmallpieces,d.DeterminingtheareaofstructuresonwhichthemaximumquantitiesofSTPLDFGsmallpieceswerecomputedtobeheldup,e.ComputingthequantityofSTPLDFGsmallpiecedebrisperunitareaofSTPstructures,Themaximumquantitiesofdebrisaccumulationon gratingresultsfromsteamgeneratorcompartmentbreakcases.Itwas determinedthatifthemaximumquantitySTPLDFGongratingwasinthe formofoneinchcubes,approximately11%ofthegratingconsideredwould becovered.Likewise,itwasdeterminedthatifthemaximumquantitySTP LDFGongratingwasintheformoftwoinchcubes,approximately3%

ofthegratingconsideredwouldbecovered.Accumulationfrombreaksin otherlocationsisanorderofmagnitudeless.Themaximumquantitiesofdebrisaccumulationonmiscellaneousstruc-turesresultsfromSteamGeneratorcompartmentbreakcases.Itwasalso determinedthatifthemaximumquantitySTPLDFGonmiscellaneous structureswasintheformofoneinchcubes,approximately7%ofthe structuresconsideredwouldbecovered;anditwasdeterminedthatifthe maximumquantitySTPLDFGonstructureswasintheformoftwoinch cubes,lessthan2%ofthemiscellaneousstructuresconsideredwouldbe covered.Accumulationfrombreaksinotherlocationsareanorderofmag-nitudeless.f.ComparingthequantityofSTPLDFGsmallpiecesdebrisperunitareaonSTPstructuresversusDDTSresults.BaseduponavisualcomparisonwithtestresultsshowninDDTSFigures2-9,2-10,2-11,3-21,3-22and3-23,maximumgratingcoverageof3%Tuesday1 stMarch,2016:19:32,Page294of393 DRAFTPART2.RAIRESPONSES(ROUND1)to11%iscomparabletowaswhatobservedinDDTStests.TableD1illustratesthiscomparison.ThemaximumquantityofdebrisaccumulationfromSteamGeneratorcom-partmentbreaksonmiscellaneousstructureswouldresultincoverageof2%to 7%ofthemiscellaneousstructuressurfacearea.Baseduponavisualcomparison withtestresultsshowninDDTSFigures2-7and2-8,thisiscomparableorlessTuesday1 stMarch,2016:19:32,Page295of393 DRAFTPART2.RAIRESPONSES(ROUND1)thanwaswhatobservedinDDTStests.TableD2illustratesthiscomparison.However,sincetheminimumoftherange(0%)ofholduponstructureswasusedinthetransportanalysisforSteamGeneratorcompartmentbreaks,the aboveresultsaretheoretical.Inpractice,itisconsideredthatnoaccumula-tiononmiscellaneousstructureswouldoccurforSteamGeneratorcompartment breaks.ForbreaksbelowtheSteamGeneratorcompartment,theRHRCom-partmentsandannulus,accumulationofdebrispersurfaceareaofstructures islessthanwhatisreportedintheDDTStestresults(DDTSTable2-2).On thebasisofthesecomparisonswithDDTSresults,itwasconcludedthatthe quantitiesofSTPLDFGcomputedtobeheldupongratingandmiscellaneous structureswerefeasible.TheDDTSdidnotfurnishnumericalquantitiesofde-briscollectionat90bends.Themaximumquantityofdebriscollectionata900 bendintheassessmentwasequivalenttoa1.8-ftcubeofLDFG.Thismaximum quantityisassociatedwithsteamgeneratorcompartmentbreaks.Debrisquan-titiesassociatedwithbreaksinotherlocationsareanorderofmagnitudeless.

Giventheplantgeometrieswheresuchretentioncanbeexpected,thereisno physicalreasonwhysuchaccumulationcouldnotfeasiblyoccur.Tuesday1 stMarch,2016:19:32,Page296of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.7SSIB,Transport:Question6eSTPResponse:(Item6e,Page67)SeveralparameterswereusedtoconcludethatthevaluesdeterminedintheDDTSareapplicabletoSTP.Theseare:a.debristypeusedintheDDTSversusdebristypetowhichDDTSvalueswereappliedtoSTP,b.debrissizeforwhichcapturefractionsarereportedintheDDTSversusthedebrissizeforwhichDDTScapturefractionsareusedinSTPdebris transportcalculations,c.thedegreetowhichthewettedconditionsthatresultedinsigni"cantdebrisentrapmentintheDDTSaresimilartotheconditionsthatcanbeexpected atSTP,d.thetypesofstructuraldebrisentrapmentsthatwereinvestigatedintheDDTSversusthetypesofstructuraldebrisentrapmentsthatarefoundat

STPe.thecongestionandjetvelocitythatwereusedintheDDTSversuswhatisexpectedatSTP,f.orientationoftheDDTStestset-upversusapplicationforSTPg.themannerinwhichtheresultsoftheDDTSwereintendedtobeusedversustheintendeduseforSTP,h.considerationofoveralldebrisquantitiesconsideredintheDDTSandex-pectedtooccuratSTP.Eachitemisdiscussedbelow.Thediscussionestablishesthebasisforcon-cludingthatthedebrisentrapmentvaluesreportedintheDDTS,asused,are applicabletoSTPconditions.DebrisType ThedebristypeinvestigatedintheDDTSwasLowDensityFiberglass(LDFG).NUKONwasusedasthetestmaterial.TheresultsoftheDDTSareappliedto potentialLDFGPost-LOCAgenerateddebrisatSTP.ThisDDTScharacteristic isdirectlyapplicabletoSTP.DebrisSizeAssumption3.1.b(LAREnclosure4-3,Reference[23]and1)statesItwasassumedthatsmallpiecesofLDFG(smallerthan6")canbetreatedas1 clumps,andlargepiecesofLDFG(largerthan6)canbetreatedas6pieces.

Sincetheassumedsizesareonthelowendofthesizerangesdescribedinthe debrisgenerationcalculation(2),thisisaconservativeassumption.TheDDTSSeparateTestProgramsuppliedrangesofnumericalen-trapmentfractionsforsmalldebris.IntheSeparateTestProgram, smalldebris,calledClass2-4,wasofthesizeshowninDDTSFigure2-6.The DDTSSeparateTestProgramsmallpiecesweregenerally2incheslong; somewerecloseto4inches,butnoneareaslargeasthe6inchsizethatwasTuesday1 stMarch,2016:19:32,Page297of393 DRAFTPART2.RAIRESPONSES(ROUND1)includedinthesmallpiecesofLDFG(LAREnclosure4-3,Reference[23]and 1).ThedebrissizedistributionusedintheIntegratedEprogramisshowninDDTSTable3-7.Rangesofnumericalentrapmentfractionsweredeveloped forsmalldebris;entrapmentestimatesformediumandlargedebriswerequal-itative.TheDDTSIntegratedESmallsize,de"nedasbeingabletopass throughagratingcell,issigni"cantlysmallerthanthesmallpiecesofLDFG, whichwereupto6inches(LAREnclosure4-3,Reference[23]and1).Insummary,thesizerangeofsmallpiecesofLDFGinthedebristransportcalculation(LAREnclosure4-3,Reference[23]and1)weresubstantiallylarger thantheClass2-4andsmallsizesforwhichentrapmentfactorswerereported ineithertheSeparateTestProgramortheIntegratedEprogram.DDTSstudiesstatedthatentrapmentincreasedwithdebrissize,particularlyforgrating.Consequently,usingDDTSentrapmentfactorsbaseduponsigni"-

cantlysmallerdebristhanconsideredinthedebristransportcalculation(LAR Enclosure4-3,Reference[23]and1)isasigni"cantconservatism,particularly wheregratingentrapmentisconcerned.WhilenotstatedintheDDTS,itisreasonabletoconcludethatat90bends,largersmallpiecesofLDFG(LAREnclosure4-3,Reference[23]and1)debris wouldbeequallyormorelikelytocollectincornersthantherelativelysmaller Class2-4andSmalldebrisconsideredintheDDTS.Onthatbasis,particularlygratingand90bendentrapmentestimatesintheDDTSareapplicabletoSTPandareasourceofconservatisminthedebris transportcalculation(LAREnclosure4-3,Reference[23]and1).WettedConditionsTheDDTSconcludedthatsubstantialdebrisentrapmentonstructuresoc-curswhenthestructuresarewetted,whilelessdebrisiscaughtondrysurfaces.

Gratingwaslesssusceptibletoentrapmentbetweenwettedanddry conditions.GiventhataLOCAjetatSTP,beingaPWR,beginswithatwo-phasemixture,itisreasonabletoconcludethattheSTPjetwilltly wetthesurfaceincomparisontothearti"ciallyintroducedwettingthatwas doneintheDDTStestset-up.Consequently,thisDDTSwetnesscharacteristic isdirectlyapplicabletoSTP.StructuralDebrisEntrapmentsTypesThestructuraldebrisentrapmentstructuresusedintheDDTSwerepipe,structural(I)beams,grating,a90turnandaMarkIIvententrance.TheDDTSinvestigatedseveralcombinationswithupstreamanddownstreamstructuralel-ements.Ingeneral,withtheexceptionoftheMarkIIvententrance,thetypes ofentrapmentstructuresusedintheDDTSaresimilartothosewhichexistat STP.ThisDDTStestset-upcharacteristicisdirectlyapplicabletoSTP.CongestionandJetVelocity Congestion.GiventhesizedbetweenBWRandPWRcontain-ments,itisrecognizedthatBWRcontainmentstendtobemorecongested.

Intuitively,itwouldappearthatincreasedcongestionwouldresultinincreased debrisentrapment.Whilegenerallytrue,theDDTSalsostatesinsection2.4.7, ofStructuralCombinations,fordownstreamobstructionsinaheavilycon-gestedcon"guration,thedebrisretentionabilityofthe(downstream)beamsis reducedwhentheyarelocatedintheturbulenceofthewakeregionbehindup-Tuesday1 stMarch,2016:19:32,Page298of393 DRAFTPART2.RAIRESPONSES(ROUND1)streammembers.Therefore,congestion,alone,isnotacompleteparameterondebrisentrapmentorapplicabilitytoaparticularcon"guration.JetVelocity.Bothforstructuralelementsandgrating,theDDTSreportedinsection2.4.3,ofApproachVelocity,thegeneraltrendthatincreasing jetapproachvelocitytendedtoresultindecreasingdebriscapturee.

AssumingthattheDDTSwasareasonablyscaledrepresentationofaBWR containment,andgiventhatPWRsingeneralandSTPinparticularwouldhave arelativelylargervolume,itisreasonabletoexpectthatthegenerallylarger volumewouldresultinequalorlowerapproachvelocitiesasthePWR/STP jetpropagatesthroughcontainment.Asaresult,itisnotexpectedthatbased uponvelocity,agenericPWRorSTPwouldhavecaptureethatare substantiallylowerthanwhatwasreportedintheDDTS.Withtheeofcongestionbeingsomewhatmoderatedbythepotentialoflocalturbulence,andgiventhatlowerapproachvelocitiestendedto resultingreaterdebriscapturee,itisreasonabletoconcludethatwhere thesetwoparametersareconcerned,theresultsoftheDDTSaregenerallyap-Tuesday1 stMarch,2016:19:32,Page299of393 DRAFTPART2.RAIRESPONSES(ROUND1)plicabletoSTP.OrientationoftheDDTSTestSet-upTheorientationofallthetestjetsintheDDTSwashorizontal.However,resultsofDDTStestareusedforanalysisofhorizontalandverticaljetpropa-gations.ItisnotedinItemviiinsection2.5(Conclusions)oftheDDTSthat thelossof"brousdebrisbycaptureonthetunnel"oor,wasnegligibleforall testsexcepttheMARKIIventgeometry,theresultsofwhichwerenotusedin theSTPanalyses.Therefore,resultsoftheDDTSareacceptableforapplication ofhorizontalandverticaljettrajectories.DDTSResultsUsageDDTSFigure3-31illustratesthefractionalcaptureofsmalldebrisbyI-beamsandpipes.ValuesinDDTSFigure3-31forCEESIwettedtestsrange fromapproximately7%to14%.Theminimumandmaximumentrapmentvalues usedinthedebristransportcalculation(LAREnclosure4-3,Reference[231and 1)are0%to13%,whicharelowerthanthoseshowninDDTSFigure3-31.DDTSFigure3-32illustratesthefractionalcaptureofsmalldebrisbyV-grating.ValuesinDDTSFigure3-32forCEESIwettedtestsrangefromap-proximately21%to36%.DDTSFigure3-33illustratesthefractionalcapture ofsmalldebrisbysplitgrating.ValuesinDDTSFigure3-33forCEESIwetted testsrangefromapproximately16%to38%.DDTSFigure3-34illustratesthe fractionalcaptureofsmalldebrisbycontinuousgrating.ValuesinDDTSFigure 3-34forCEESIwettedandpartiallywettedtestsrangefromapproximately3%

to29%.Theminimumandmaximumentrapmentvaluesusedindebristrans-portcalculation(1)are5%to35%,whicharelowerthanthoseshowninDDTS Figures3-32and3-33,andaresimilartothoseinDDTSFigure3-34giventhat thelowendoftherangeinDDTSFigure3-34isstronglyin"uencedbypartial versussigni"cantwetting.DDTSFigure3-35illustratesthefractionalcaptureofsmalldebrisbytheauxiliarytankbend,i.e.,the900bend.ValuesinDDTSFigure3-35forCEESI wettedtestsrangefromapproximately3%to31%.Theminimumandmaximum entrapmentvaluesusedinthedebristransportcalculation(LAREnclosure4-3, Reference[23]and1)are3%to29%,whicharewithintherangeshowninDDTS Figure3-35.ItisnotedthatinDDTSFigure3-31smalldebriscapturefractionsbyI-beamsandpipesrepresentindividualobstructions.Therefore,formultiplestruc-turalelements,aformulationsimilartothatwhichwasusedfor90bendsandgratingareappropriate,i.e.,oftheform ni=0 (1.0F misc)where F miscisthecapturefractionofonemiscellaneousstructuralobstruc-tionand ninthe n=N miscwhichdenotesthenumberofsuchobstructionstobemultipliedinthe1CartesianProduct.Instead,thedebristransportcalculation (LAREnclosure4-3,Reference[23]and1)uses,inasingleterminall cases,whichisaconservativeapproach.OverallDebrisQuantitiesTuesday1 stMarch,2016:19:32,Page300of393 DRAFTPART2.RAIRESPONSES(ROUND1)IntheSTPCASAGrandeanalysis,over640,000breakcases,ranginginloca-tion,breaksizeandprobabilityofoccurrence,areconsidered.Ofthese,breaks resultingintotalLDFGdebrisgeneratedinexcessof100cubicfeethavea probabilityofoccurrenceinthe1.0E-15range,hencetheyareoflittlepractical interest.ThequantitiesofLDFGdebrisconsideredhelduponmiscellaneous structures,gratingandat90-degreeturnsforbreakcasesassociatedwithtotal LDFGdebrisgeneratedupto100cubicfeetarerelativelysmallwhencompared withthequantitiesofdebrisheldupintheDDTStests.Consequently,there-sultsoftheDDTStestingareapplicabletoSTPconditionsintermsofquantities ofdebrisconsideredtobehelduponmiscellaneousstructures,gratingandat 90-degreeturns.

SummaryInsummary,baseduponsimilarityindebristype,debrissizesconsidered,thedegreetowhichwettedconditionscanbeexpected,similarityintypesof structuraldebrisentrapments,congestionandjetvelocitycomparison,theman-nerinwhichtheresultsoftheDDTSwereusedandoveralldebrisquantities,it isconcludedthat,asused,theresultsoftheDDTSwereappropriatelyapplied toSTPconditions.

Reference:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3,6/10//2014.2.3.6.8SSIB,Transport:Question7a STPResponse:(Item7a,Page68)Section2.2.18,WashdownTransportFractions,ofLAREnclosure4-3doesnotcontainanexplicitevaluationofthelikelihoodthatapieceofdebristhat hasbeenblownthroughoneormoregratingswillbemorelikelytosubsequently washdownthroughgratings.NUREG/CR-6369,Vol.2DrywellDebrisTrans-portStudy:ExperimentalWorkFinalReport(DDTS)didnotattachtestdebris togratingbyimpingementinajetthroughgratingswhenstudyingwashdown

(1).However,basedonthefollowing,itisconcludedthatthedebristhatwasusedinsection4oftheDDTS,SeparateTestProgramtoEvaluateWashdown ofInsulationDebrisbyECCSFlow,(hereafterreferredtoaswashdown)ad-equatelyrepresentsthedebristhatwasconsideredsusceptibletowashdownin theSTPanalysis,andtheresultsoftheDDTScanbeappliedtoSTPwashdown

calculations.Section5.4ofreference23inLAREnclosure4-3states,forthisanalysis,itwasconservativelyassumedthatalldebriswouldbewashedtolowercontain-mentwiththeexceptionofanysmallandlargepiecedebrisheldupongrating asitiswasheddown.IntheDDTSwashdowndiscussion,Smallwashdown debris,isdescribedas:Insulationdebrisofalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.Typicallythesepieceswereabout1.5 insizeandpossessedlittleoftheoriginalstructureorthechemical binding.InCEESItests,theywerefoundtohavebeenattachedtoTuesday1 stMarch,2016:19:32,Page301of393 DRAFTPART2.RAIRESPONSES(ROUND1)thewetgratings.Thesedebrispieceswereobtaineddirectlyfromblast-jetexperimentsconductedpreviouslybySEA(seeSection3).

Thesedebrispiecesweremainlyusedinspraytests.Notethecharacterizationofalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.TheDDTSwashdowndiscussionstatesthatcompacteddebris islesspronetoerosion,whileloosedebrisismorelikelytoerode.Forexample, DDTSwashdownsection4.4.1,Con"rmatoryTests,item3statesPieces cientlylargerthanthegrating(classi"edasM-O,M-JandLinSection4.2.2) possesststructureandarenotsusceptibletobeingforcedthroughthe gratingclearancesinashortperiodoftime.Erosion(ifany)occursoveralonger periodoftime.Themechanismofdebrisgeneration,passagethroughagratingandsubse-quentcaptureonagratingisasfollows:a.Theprocessofdebrisgenerationdestroystheinitialcompactformofde-bris.b.Theprocessofdebris,whichislargerthantheopeningsizeofthegrating,passingthroughalevelofgratingfurtherdisruptsthecompactnessofthe

debris.c.Theprocessofinertialcaptureofdebrisongratingincludescompactionasthedebriscollideswiththegrating,underthein"uenceofjetforces.As moredebrisiscaughtonthegrating,thedebrisisfurthercompacted,both undertheactionofthejetforcesactingonitandtheeof"additional layers"beingcompressedbyjetforces.Therefore,whiletheprocessofpassingthroughalevelofgratingmayloosendebris,theprocessofcaptureandretentionhastheoppositecompaction.

Forexample,insection2.4.10,GratingDebrisDegradationTests,oftheDDTS, itwasobservedthatdebriscaughtongratingandsubjectedtojetforcestended toretainitsstructure,e.g.,Noapparentbreakdownofeitherthe1/2or1/4" insulationdebriswasseen,althoughthepiecesbowedbetweenthegratingbars andtheedgesoftheinsulationpieceswrappedbackaroundthegratebarsto "apbehindthegrate...Incontrast,thedebrisusedinthewashdowntestshada...alight,loose,andwell-aeratedtexture...Itisthereforeconcludedthatresultsobtained fromwashdowntestingof...light,loose,andwell-aeratedtexturedebrisis representativeandmaybeconservativewhencomparedtodebristhathasbeen compactedongratingbyacombinationofjetforcesandpotentiallymultiple layersofdebris.

Reference:

1.NUREG/CR-6369,Vol.2.DrywellDebrisTransportStudy:ExperimentalWorkFinalReport.September1999.2.3.6.9SSIB,Transport:Question7b STPResponse:(Item7b,Page68)Tuesday1 stMarch,2016:19:32,Page302of393 DRAFTPART2.RAIRESPONSES(ROUND1)Thesigni"cantlylongerwashdownperiodsatSTPthanthoseconsideredintheDDTSareinconsequentialtotheSTPanalysis.SectionVl.5,Blow-down/WashdownConclusion,ofNEI04-07Vol-2(SER)(LAREnclosure4-3, Reference[45])whichisguidancethataddressestheentirepost-LOCAmission timeonadeterministicbasis,states:theDDTSassessedtheerosionofLDFG byCSs(i.e.,spray)aslessthan1percent.Inreality,theerosionmaybesigni"-

cantlylessthan1percent.The1percentvaluewasassumedtobeconservative butnotfarfromreality.Thebasisofthewashdownparametersusedinthe transportanalysiswasNEI04-07Vol-2(SER),nottheDDTS.2.3.6.10SSIB,Transport:Question7c STPResponse:(Item7c,Page68)Thedebristransportanalysistakesintoaccountthepossibilitythatdebristhatiswasheddownthroughonelevelofgratingmaybemorelikelytowash throughsubsequentlevels.Section5.4ofreference23inLAREnclosure4-3statesTheresultsoftheDDTStestingshowedthatapproximately40-50%ofsmall"berglassdebrisland-ingongratingwouldbewashedthroughthegratingduetospray"ows(14).

Duetothefactthatmanyofthe"owpathstothecontainmentpoolwouldpass throughmultiplelevelsofgrating,itwasassumedthat0-25%ofsmallpieces wouldbehelduponeachadditionalgratinglevel...Inthetransportcalculation,theaboverangeswereimplementedasfollows:

• Forthe"rstgrating,a50%fractionwasused,resultingin50%hold-upand50%washthrough.

• Forallsubsequentgratings,a0%fractionwasused,thusresultinginnoholdupofdebrisatsubsequentgrating(s).Thisapproachtakesintoaccountthepossibilitythatdebriswasheddownthroughonelevelofgratingmaybemorelikelytowashthroughsubsequent levels.ItisnotedthattheDDTSdoesnotincludeanydiscussionthatitmay bemorelikelyforapieceofdebristhathasbeenblownthroughonelevelof gratingstobemorelikelytowashthroughsubsequentlevels.Nevertheless,itis concludedthatthedebristransportanalysistakesintoaccountthepossibility thatdebristhatiswasheddownthroughonelevelofgratingmaybemorelikely towashthroughsubsequentlevels.2.3.6.11SSIB,Transport:Question7d STPResponse:(Item7d,Page68)TheresponsetoSSIB,Transport,RAI8statesTheresponsepreviouslypro-videdinSection5.a.5(LAREnclosure5)wasnotimplemented.CASAGrande assumesnocreditforholdupofpartiallysubmergeddebrisontheconcreteof theoperatingdeckaspreviouslydescribed.ThishasbeenenteredintheSTP correctiveactionprogramforcorrectioninfuturesubmittals.Thesigni"cantlyhighervelocitiesthatmayoccurwithsheeting"owatthebeginningofwashdownareinherentlyconsideredbytheassumptionthatall debrislandingonconcretewouldbewashedtolowercontainmentasdescribed inthefollowingquote.Tuesday1 stMarch,2016:19:32,Page303of393 DRAFTPART2.RAIRESPONSES(ROUND1)Section5.4ofreference23inLAREnclosure4-3statesDuringthewash-downphaseofaLOCA,debriswouldbetransporteddowntothecontainment poolbyoperationofthecontainmentspraysystem.Signi"cantamountsofde-briscould,however,becapturedontheconcrete"oorsandgratedareasabove thecontainment"oorascontainmentspraywatertransportingthedebrisdrains throughgratingtoreachthepool...However,forthisanalysis,itwasconserva-tivelyassumedthatalldebriswouldbewashedtolowercontainmentwiththe exceptionofanysmallandlargepiecedebrisheldupongratingasitiswashed down.2.3.6.12SSIB,Transport:Question7e STPResponse:(Item7e,Page68)Theobservationiscorrect,incorrectvaluesofFWGwereusedinSection5.a.3;the0.40and0.50shouldhavebeenreversed.Inotherwords,the0.50 shouldhavebeenimplementedinthe"rstequation(theequationwhichhasa solutionof0.19),andthe0.40shouldhavebeimplementedintheotherequation.

Also,inaccordwiththeequation,thecorrectde"nitionofFWGisfractionof debriswashedthroughthe"rstlevelofgrating.If40%ofdebrislandingon gratingiswasheddownthroughthegrating,then60%isheldup.Reference23 ofLAREncl.4-3wasrevisedtorevision3andcorrectedthis(1,Equation25 and26).Theresultingchangestototaldebristransportfractionsarediscussed intheresponsetoSSIBRAI6b,above.

References:

1.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCal-culation.Revision3.6/10/2014.2.Morton,D.P.,Tejada,J.J.,Zolan,A.,SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume3,APracticalGuidetoSensitivityAnalysisofa Large-scaleComputerSimulationModel.,STP-RIGSI191-ARAI.01,Rev.3.0, February2014.TheUniversityofTexasatAustin.2.3.6.13SSIB,Transport:Question7f STPResponse:(Item7f,Page68)Theleadingparagraphpertainsonlytowashdownfractions.ThediscrepancyhasbeenenteredintheSTPcorrectiveactionprogramfortrackingforcorrection infuturesubmittals.2.3.6.14SSIB,Transport:Question8a STPResponse:(Item8a,Page69)ThefollowingresponseisforSSIBRAI8athroughSSIBRAI8e.There-sponsepreviouslyprovidedinSection5.a.5(LAREnclosure5)wasnotimple-mented.CASAGrandeassumesnocreditforholdupofpartiallysubmerged debrisontheconcreteoftheoperatingdeck.Section5.a.5ofLAREnclosure5 wasaresponsetoNRCSComment/Question2.5.a.5inthe2013Submittal whichstates:Thebasisfortheproposedchangeisthattheresidualriskfromtheremain-ingGSI-191issues(e.g.,thosenotalreadyaddressedinadeterministicmanner) satis"esthecriteriainRegulatoryGuide(RG)1.174,Revision2,AnApproach ForUsingProbabilisticRiskAssessmentInRisk-InformedDecisionsonPlant-Tuesday1 stMarch,2016:19:32,Page304of393 DRAFTPART2.RAIRESPONSES(ROUND1)Speci"cChangestotheLicensingBasis,May2011(ADAMSAccessionNo.ML100910006).However,theapplicationdoesnotappeartoprovidest detailfortheNRCtodeterminewhetherthecriteriainRG1.174havebeen met.PleasedescribeindetailhowtheprinciplesofRG1.174criteriaregarding safetymargin,defense-in-depth(DID),andchangeinriskaremet.Inparticular, pleaseincludethefollowing:a.Regardingthetechnicalevaluationthatsupportstheriskmet-rics,theProjectSummary(Enclosure4totheapplication)describes numerousareaswherethetechnicalevaluationdeviatesfromtheap-provedguidanceforaddressingGS1191.However,theapplication provideslittleornoinformationonhowtheissueswereaddressed.

PleaseprovideadiscussionintdetailtopermitNRC reviewofthemethods,bases,assumptions,acceptancecriteria,and results.Iftestresultsareusedtodevelopprobabilitydistributions, pleasedescribehowthesedistributionsweredeterminedandusedin theoverallriskevaluation.Pleasealsoprovidethebasisfortheaccep-tancecriteriachosen.TheNRCrequiresadditionalinformation inthefollowingareas:5)TimedependenttransportThecorrectresponsetoquestion5.a.5istheonlytimedependenttransportthatoccursistheaccumulationofdebrisonthestrainers.2.3.6.15SSIB,Transport:Question8b STPResponse:(Item8b,Page69)SeeresponsetoSSIBRAI8a.2.3.6.16SSIB,Transport:Question8c STPResponse:(Item8c,Page69)SeeresponsetoSSIBRAI8a.2.3.6.17SSIB,Transport:Question8d STPResponse:(Item8d,Page69)SeeresponsetoSSIBRAI8a.2.3.6.18SSIB,Transport:Question8e STPResponse:(Item8e,Page69)SeeresponsetoSSIBRAI8a.2.3.6.19SSIB,Transport:Question10 STPResponse:(Item10,Page69)Thefailureandsubsequenttransportofunquali"edcoatingsissprayde-pendent(LAREnclosure4-3Reference12).Ifthereisnospray(spraysare secured),thereisnoadditionalfailedinventoryavailablefortransport.CASA Grandedoesnotincludeapredictivemodelofdebristransport,soconsidera-tionofadditionaltransportmechanismsmustbeincludedintheassignedfailure andtransportfactors.Thereareothertransportmechanismsbesideswashdown fromcontainmentspraysthatcouldcausefailedunquali"edcoatingsinventoryTuesday1 stMarch,2016:19:32,Page305of393 DRAFTPART2.RAIRESPONSES(ROUND1)totransport,suchasfreefallandcondensate"ow.However,noadditionalun-quali"edcoatingsareassumedtofailaftercontainmentspraysaresecured.The unquali"edcoatingsinventorypresumedfailed,computedastheproductofthe totalcoatingsinventoryandthetime-dependentfailurefraction(unquali"ed washdown),wasaddedtothecontainmentpoolwithinthe"rst10minutes(See theresponsetoESGB,CoatingsRAI4and5providedintheSTPlettertothe NRCSNOC-AE-00143103,datedMay22,2014,ML14149A434).Condensateonsurfacescouldpotentiallycarryparticlesofalreadyfailedunquali"edcoatingstothepoolaftercontainmentspraysaresecured.However, STPinputstoCASAGrandedonotassumetheadditionalfailureofunquali"ed coatingsonceContainmentSpraysaresecured,andnotime-dependentarrival wascredited.Theunquali"edcoatingsinventorythatfailed,computedasthe productofthetotalinventoryandthefailuretiming(unquali"edwashdown) fraction,wasaddedtothecontainmentpoolwithinthe"rst10minutes(See responsetoESGB,CoatingsRAI4).2.3.6.20SSIB,HeadLossandChemicalBumpUp:Question 14STPResponse:(Item14,Page70)Thecleanplantcriteriaisnotthebasisforusing1/16 thinchlimitforchem-icalbumpup.Any"berbuild-uplessthan1/16 thin.(thinbed)isunlikelytoloadcontigu-ously,allowingchemicalprecipitantstopassthroughthestrainermeshwithout causingasigni"canthead-lossincrease.Conventionalheadlossforbreaksthat donotformathinbedarecalculatedandevaluatedintheanalysis.Debrisbedsof1/16 thin.orthickeraresubjectedtochemicalhead-lossfactorsasdescribedinLAREnclosure4-3,Section5.6.3.Eachsimulatedbreakhasits owntime-dependentconventionalheadlossthatiscalculatedbasedondebris accumulationand"owrate,whichisthenaddedtoabaselineclean-strainer headlossof0.220ft-H20[1].Chemicalfactorsareappliedtotheconventional headlosswhenthetemperatureislessthan140

+/-5Fandthe"berloadexceeds 1/16 thin.equivalentthickness.AsensitivityanalysiswasperformedinCASAGrandebyapplyingthechem-icalbump-upfactortoathinbedthresholdvalueof0in.toassessthee ofthatvariableusingthemaximumamountofconservatism.Thissensitivity analysisshowednoeonTherefore,usingachemicalmultiplieron anythinglessthan1/16 thin.wouldnotin"uencerisk.AfurthersensitivitystudyindicatesthatthemultiplierontheMBLOCAconditionmustbehigherthan60 toincreasetheriskassignedbyCASAGrandeCase01(allequipmentoperates).

TheSBLOCAheadlossfactorinthissensitivity,althoughhigherthanassumed intheLAR,doesnotin"uencetheriskbecausenoneoftheSBLOCAscenarios formathinbed.

References:

1.66-9088089-000.SouthTexasProjectTestReportforECCSStrainerTest-ing.Revision0:August29,20082.SteamGeneratorTubeIntegrityandChemicalEngineeringBranch.RAIESGB-1-5Revision0Tuesday1 stMarch,2016:19:32,Page306of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.21SSIB,HeadLossandChemicalBumpUp:Question 15aSTPResponse:(Item15a,Page71)Correlationsareimportantforcapturingsubtletrendsandinteractionsbe-tweenphysicalvariablesincludingcombinationsofdebrisloadsand morphologies.Strainerquali"cationtests,likewise,donottestallpossiblede-brisloadsandmorphologiespresentunderplantconditions.However,incombi-nation,correlationshelpidentifycombinationsofconcern,especiallyacrossthe fullspectrumofRIanalysis,andstrainertestsprovideproofofperformancefor themostchallengingconditionsidenti"ed.Predictionsofheadlossandcon"r-matorystrainertestingprovidecomplementaryandessentialelementsforfull understandingofstrainer-relatedECCSfailure.OtherRAIresponsesaddress moredirectlytheissueofvalidationoverappropriaterangesofplantconditions.2.3.6.22SSIB,HeadLossandChemicalBumpUp:Question 15bSTPResponse:(Item15b,Page71)Lateralinhomogeneity(acrossthefaceofastrainersurface)isalwayspre-sumedtocauselesstotalheadlossthanacontiguousuniformbedofthesame composition.Lateralinhomogeneityiscommonlyobservedinstrainermodule testingwhereitcanbedtoformacontiguousbedthatleadstomaxi-mumobservedpressuredrop.STPagreesthatlateralinhomogeneityislikelyto occurandwillreducetheactualheadlossthatoccurscomparedtothemaximum headlosspredictedbycorrelation.Inhomogeneouscompositionthroughthethicknessofthebedmayexistthatelevatetheobservedheadloss.Twoexamplesofpotentialconcernare(1)chem-icalproductsarrivinginbulkatthetopofapre-establishedbed,and(2)im-pactionof"nelydivideddebrisintheholesofthestrainerplatecausingalocal reductioninporosity.Bothconditionsareinvestigatedinthesupplementary report(Enclosure1).Althoughnoevidenceofbulkchemicalprecipitationpo-tentialhasbeenobservedforSTP,simulationsofathinlayeroflowporosity, high-S vdebrisatthetopofthebedshowafactorof2increaseinheadlosscom-paredtothesamemassofmaterialdistributedthroughoutthebed(Enclosure 1).Localimpactionof"berinthestrainerplateholeswasobservedintheCHLE-10UNMtestwhichused"berpreprocessedinablender.Theteststartedthe introductionofchemicalsat6.75dayswithamaximum1400%increaseinhead losscomparedtothe1-daysteadystatevalue(LAREncl.4-3,Ref.[17]).Calcula-tionsshowcomparablepotentialhead-lossincreasewhenporosityinthestrainer plateori"ceisgreatlyreduced.Largequantitiesofextremelysmall"bershards (brokenglassstrands)arenotexpectedtobeproducedintheLOCAZOIenvi-ronment,andarenotincludedaspartofthemodi"edNEIdebris-preparation protocol.2.3.6.23SSIB,HeadLossandChemicalBumpUp:Question 15cSTPResponse:(Item15c,Page71)STPhasonlyonestrainercon"gurationthatisconsistentforall3trains.Tuesday1 stMarch,2016:19:32,Page307of393 DRAFTPART2.RAIRESPONSES(ROUND1)ThePCIdesignwascon"rmedbytestingtoloaduniformlyacrossthefaceofthestrainersurfacearea,sothepotentialforgeometricvariationsatSTPisgreatly

minimized.Maximum"owvelocitiesof0.0086ft/satSTParenotwithintheHTVLtestrange,butlowvelocitiesarerepresentedintheARL"umetestsandintheUNM verticalcolumntests,whichareavailableforvalidationoftheNUREG/CR-6224 correlationthatwasimplementedfortheLAR.Thesupplementaryreportac-companyingthisresponse(Enclosure1)providesameansformorerobustcor-relationof"owconditionsintermsofReynoldsnumberthatencompassesve-locity,waterproperties,andbedparametersofporosityandsurface-to-volume ratio.Theproposedcorrelationillustratesthatexistingtestsusedtovalidate NUREG/CR-6224exposethebedtoamuchwiderrangeof"owconditions(two ordersofmagnitude)thanpreviouslythought.Theexpandedrangeofcondi-tionssupportsapplicabilityforRIuseofacorrelationprovidedthatacceptable comparisonstotestdatacanbeachieved.Reynoldsnumberforinternal"owthroughadebrisbedisde"nedas, Re= Aµ(1m)S v (1)whereis"uiddensity,µis"uidviscosity, w A,isstrainerapproachvelocity,m,ismixtureporosity,and S vissurface-to-volumeratioforthesoliddebris.Theseattributescanbedeterminedindependentlyofanypresumedhead-losscorrelationforanyhomogeneousmixtureofdebris.DistributionsofReynoldsnumberwerecompiledfromCASAGrandeanaly-sisconditionedonLOCAcategoryforbedcon"gurationsand"owratesexisting attheendofeachbreakscenario.Whenthesludgecompactionlimitisnot enforced,expectedvalues(means)andmaximaofReynoldsnumberforeach LOCAcategoryareBreakSizeSmallMediumLargeAvg.Reynolds#0.02370.080.3105 MaxReynolds#0.07480.25651.748ThecumulativedistributionofReynoldsnumberforlargebreakscenariosisillustratedinFig.A,whichshowsaverynarrowrangeofinterest.Manycombi-nationsofEq.(1)parametersleadtosimilar"owregimesasde"nedbyReynolds number.Thesupplementaryreport(Enclosure1)proposesarobustcorrelation basedonanexplicitrepresentationofReynoldsnumberanddemonstratesthat typicalHTVLtestingdoesinfactspan(andlikelyexceeds)the"owregimesof interestforSTP"owconditions.Giventheadequateoverlapof"owconditions tested,discrepanciesbetweenblindpredictionsofacalibratedmodelandHTVL testdatacanbeattributedtotbedcompressiondescriptionsandto localstrati"cationthatthespatialdistributionofporosityandsurface area-to-volumeratio.Insummary,velocityisonlyonefactorthatcontributesto"owregimeinacompositedebrisbed,butmanyfactorsinteractasshowninEq.(1).When allotherfactorsareequalexceptvelocity,conventionalinterpretationsofhead-losscorrelationsindicatethatlowervelocityleadstolowerheadloss,lessbedTuesday1 stMarch,2016:19:32,Page308of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:CumulativeprobabilitydistributionforReynoldsnumberexperiencedunderlarge-breakscenarios.compression,andslowermigrationofparticulates.Therefore,sincecomparableReynolds"owconditionshavebeenachievedintheteststhroughacombination offactors,itisreasonabletoexpectthatlowerpressuredropswouldhavebeen observedwhentestingatlowervelocitiesidenticallymatchingplantconditions.

Reynoldssimilitudeextendstotheplantcon"guration,sothecurrentsuiteof testconditionscanbeconsideredadequateforvalidation.2.3.6.24SSIB,HeadLossandChemicalBumpUp:Question 15dSTPResponse:(Item15d,Page71)PrincipaluncertaintiesexistinthedragareaparameterSv(solidsurface-to-volumeratio)andinthebedporosity.ConclusionsoftheSTPLARarenot becauseuncertaintyinmaterialpropertiesiscompensatedbythefactor of5uncertaintyboundandbecauseintendedapplicationofabedcompaction limitobviatesconcernsregardinglocalporosity.Thesupplementaryreport(Enclosure1)providedwiththeSSIBRAIre-sponsesusesdirectmeasurementofsurface-to-volumeratiotominimizeuncer-taintiesindebrisproperties.Forthecalibrationtest,measuredvaluesofSvare approximately250%lessforacrylicpaintdebris,whichisasurrogateforqual-i"edepoxy,thanthestandardgeometricapproximationforquali"edepoxyin LAREnclosure4-3.High-"delityreproductionsofthetestdataareobtained usingmeasuredSvwhenbedcompressionisallowedtoequilibratewithpressure dropandnocreditistakenforrelaxation(thicknessrecovery)afterexposureto hightialpressure.Bycomparison,applicationofNUREG/CR-6224with afactorof5uncertaintyboundconsistentlyoverpredictsalltestmeasurements.Formulasformixtureporosityarewelldevelopedbetweenthephysicallimitsofsludgecompactionandtheoreticalporosityofclean"ber.Uncertaintiesinbed porosityarethereforelargelycausedbyuncertaintiesinpotentiallocalstrati"-

cation,whichisaddressedintheresponsetoSSIBRAI15b,andbyperformanceTuesday1 stMarch,2016:19:32,Page309of393 DRAFTPART2.RAIRESPONSES(ROUND1)ofthebedcompressionmodel.TheSTPanalysisintendedtoapplythesludgecompactionlimitthroughoutthebedofhomogeneouslymixedcompositionto minimizetheoftheseuncertainties.(Note:correctimplementationofthe sludgelimitassumptionwillleadtoanincreaseinResponsestoSSIB RAI18band18cprovidefurtherdetail.)2.3.6.25SSIB,HeadLossandChemicalBumpUp:Question 16aSTPResponse:(Item16a,Page71)VerticallooptestsconductedbySTPareimportanttodemonstratethecon-clusionthattheSTPLARapproachforpredictivehead-lossestimation,which includesanintendedsludgecompactionlimitandafactorof5uncertaintybound appliedtotheNUREG/CR-6224model,adequatelyenvelopesvariabilitynoted bythebetweentfacilitiesundersimilarconditions.Itisnoted,how-ever,thatimportantddoexistbetweenteststhatareoftendescribed assimilar.Forexample,whileHTVLSeries2Test8emulatesastrainertest withrespecttodebrisquantityand"owconditions,debrispreparationwassub-stantiallyt;theHTVLtestusedNEIprepareddebrisandtheARLtest usedblenderprocesseddebris.VerticallooptestsconductedbySTParevalidtotheextentthattheyrepro-duce"owconditionsinrepresentativedebriscon"gurationssothattheaggregate head-lossapproachcanbedemonstratedtoboundprototypicalconditions.The approachappliedintheSTPLARboundsalltotalhead-lossmeasurements takeninprototypicaltestconditions.Whileitisdesirabletohaveapredictive approachthatcanreproducealltestconditionswithhigh"delity,uncertainties inbedcon"gurationanddebrischaracteristicscandominatethecomparisonof replicatetestsandnumericalsimulations.HTVLtestsweredesignedtorepresent themostprevalentconditionsexpected,andsuccessfulcomparisonoftheSTP LARcalculationmethodto"umetestdata,asdemonstratedintheresponseto ESGB,ChemicalRAI2,provideshighcon"dencethatunderprediction willnotskewtheriskquanti"cation.Deterministicperspectivesrelatedtothede"nitionofaworst,ormostchal-lenging,setofconditionshavelongdominatedassessmentoftestvalidityand acceptability.Therisk-informedperspectivecombinesthatinterestinchalleng-ingconditionswiththeirfrequencyofoccurrence,sothatjudgmentoftestva-liditycannowincludeabroaderinterpretationofapplicabilitytoplant-speci"c conditions.ThesupplementarywhitepaperprovidedwithSSIBRAIresponses (Enclosure1)explainsanewperspectiveonhead-losscorrelationbasedon Reynoldsnumberforinternal"ow.AdistributionofReynoldsnumberwasextractedfromtheCASAGrandeanalysisspectrumforalllargebreakhistoriesinatypicalstatisticalreplicate.

AsshownintheresponsetoSSIBRAI15cand17c,typicalinternalReynolds numbersforaLBLOCAvarybetween0.1and1whenthesludgecompaction limitisnotenforced.STPverticalcolumntestswereusedtocalibratethenew modeloveranadequaterangeofReynoldsnumberspanningfrom0.2to4.5.The newcorrelationshowsthatexistingverticalhead-losstestsbroadlyrepresentthe rangeneededforpredictionsintheRIapplication.Thesupplementaryreportfurtherdemonstratesthatthealternativehead-Tuesday1 stMarch,2016:19:32,Page310of393 DRAFTPART2.RAIRESPONSES(ROUND1)losscorrelationisconsistentwithtestdataandproducespredictedhead-lossvalueswellbelowthoseproducedbytheNUREG/CR-6224correlationasimple-mentedintheLAR.Recallthatthesludgelimitforbedcompactionisintended asaconstraintonminimumbedporosityandthatafactorof5isappliedto coveruncertaintiesinbedproperties,correlation"delity,andtestingvariability betweenfacilities.2.3.6.26SSIB,HeadLossandChemicalBumpUp:Question 16bSTPResponse:(Item16b,Page72)VerticallooptestsareimportanttoconclusionsintheSTPLARonlytotheextentthattheycorroboratetheconclusionthathead-losspredictionsmadefor uniformcontiguousbedsshouldboundactualstrainerperformanceforsimilar totaldebrisloadsand"owconditions.Verticaltestresultsalonearenotintended asexclusiveprotectionofthisassumption.Thefactorof5uncertaintyappliedto theNUREG/CR-6224head-losspredictionsalsohelpstoensurethisassumption.

SeetheresponsestoSSIBRAI16aandSSIBRAI28foradditionaldiscussion ofthisstrategy.Verticallooptestsconductedundersite-speci"cconditionsshouldcorrelateto"umetestsconductedundersimilarconditionsandtoheadlossesthatoccurin theplanttotheextentthatmoredebrisand/orhighervelocity,and/orreduced porosityallproducehigherheadlossinalltestcon"gurations.However,HTVL Test8,anintendedreplicateoftheARL"umetest,resultedinamuchlower headlossatacomparabletemperatureanda"owrateapproximately2.5times higherthanthe"umetest.Manydisparitiesinthetestconditionsincluding debrispreparationcontributedtothisdiscrepancy.Inthisapplication,correlationdoesnotimplyaneedforperfectagree-mentbetweenmodelandtests.Conclusionsintheapplicationareconstructed aroundlimitingassumptionsthatcompensateforknownde"cienciesinthe NUREG/CR-6224head-lossprediction,oneofthemostnotablede"cienciesbe-ingthebedcompressionresponseformixeddebriscomposition.Debristransportedbyassumptiontothehorizontalstrainersurfacewouldresultinadebrisbedcomposedof"neandsmall"bersizesloadedwith100%of particulatereachingthepool.Allmaterialsareassumedtobefullytransportable withtheambient"owvelocity,whichfurtherconsistencywithactualplant transportofsmalland"nematerial.Theassumptionofmaximumcompression shouldresultinhead-losstrendsthatarehigherthanmeasuredinthevertical loop.Verticalhead-losstestsincombinationwithassumptionsimplementedwith theresultingcorrelationprovidecon"dencethathead-losstrendsarereasonably (butnotunduly)conservativewithrespecttoactualplantstrainerperformance.Headlossobservedinverticaltestingandinstrainertestingisdrivenby"owconditionswithinthedebrisbedandnotbytheactualconstituentsof thedebris.Thissimilitudeisthebasisforsubstitutionofparticulateshaving similarsizedistributions.Therefore,headlosseswillbecomparableforsimi-lar"owconditionsde"nedby:velocity,"uidproperties,porosityanddragarea

(S v).Thesupplementaryreport(Enclosure1)accompanyingtheseSSIBRAIresponsesfurtheremphasizestheimportanceofrobustcorrelationbasedonin-ternal"owconditions.ResponsestoSSIBRAIs15c,17c,and16adiscussrangesTuesday1 stMarch,2016:19:32,Page311of393 DRAFTPART2.RAIRESPONSES(ROUND1)ofReynoldsnumbercoveredbytestingandbythespectrumofbreakscoveredinCASAGrande.Bedmorphologyintheformofalternatediscretestrati"cation isaddressedintheresponsetotheSSIBRAI15b.Intotal,thesecomparisons demonstratethattheLARapproachtohead-losspredictionwillreproducethe properbehaviorwithrespectto"owrate,debrisloadandtemperature,while overestimatingactualstrainerperformanceundersimilarconditions.2.3.6.27SSIB,HeadLossandChemicalBumpUp:Question 16cSTPResponse:(Item16c,Page72)ThepurposeofusingapredictivecorrelationintheSTPLARistorepro-duceobservedtrendsinheadlossasafunctionofdebriscompositionand"ow conditionssothatcrediblesensitivitystudiescanbeperformedtodetermine drivingfactorsandsubtleinteractionsthathavenotbeenanticipatedpriorto theRIclosurepilotstudy.Implementationofthecorrelation,includingsludge-limitcompactionandafactorof5uncertaintybound,isdesignedtoprovide con"dencethatpredictionsboundrealisticstrainerperformanceforthemajor-ityofdebriscombinationsand"owconditionsthatareexperiencedintheplant.

Noneofthesegoalsrequireexactagreementbetweentestconditionsandcorre-lation.Infact,thecorrelationutilizedintheverticalhead-losstestreportdid notincludethesamehead-lossassumptionsusedinthe"nalimplementation.Forexample,theresponsetoESGB,ChemicalRAI2citescompar-isonsofmaximumhead-lossvaluesobservedin"umetestingplacedincontextas percentilesofallhead-losspredictionsobtainedfromtheCase01(allequipment operates)CASAGrandeanalyses(whichincludethefactorof5uncertainty, butnotthefulleofsludge-limitcompaction).Measuredmaximaliewithin theenvelopeofcomputedmaxima(evenwithoutthefulleofsludge-limit compaction),andpredictedmaximaliewellabovethestrainer-collapsethresh-oldof9.35ft.NoneoftheARL"umetestsmeasuredheadlossexceedingthe strainerbucklinglimit.Thesecomparisonsprovideassurancethatthecorrela-tionasimplementedservesitsdualroleoftrackingtheinteractionofcomplex debrisbehaviorandprovidingreasonablyconservativeboundsonactualstrainer performance.2.3.6.28SSIB,HeadLossandChemicalBumpUp:Question 16dSTPResponse:(Item16d,Page72)AsimplementedintheLARwithacodelevelerrorthatrevertedallcasestomixed-bedporositywithoutcompression(describedintheresponsestoSSIB-RAI18band18c),andafactorof5uncertaintybound,theNUREG/CR-6224 correlationpredictionsboundthemeasuredmaximumheadlossesreportedfor theFebruary(1)andJuly(2)2008tests.TheoneexceptionisFebruaryTest 3thatwasdeterminedtobenon-representative.ResponsetoESGB,Chemical RAI2citescomparisonsofmaximumhead-lossvaluesobservedin"ume testingplacedincontextaspercentilesofallhead-losspredictionsobtainedfrom Case01(allequipmentoperates)CASAGrandeanalyses(whichincludethe factorof5uncertainty,butnotthefulleofsludge-limitcompaction).DBA testsarewellabovethe95thpercentileofallsimulatedbreaksandyetwellbelowTuesday1 stMarch,2016:19:32,Page312of393 DRAFTPART2.RAIRESPONSES(ROUND1)predictedmaximathatincludechemicalOnecriticismoftheSTP"umetestshasbeenpossibleunderestimationof"berdebrisvolume,andonepossiblede"ciencyofthepredictivemodelisim-propersludgecompaction.Distributionsofpredictedhead-lossincludedebris volumesconsistentwith17DZOIthatareassumedforNukon"berglass,and atleastonetestincluded"bervolumesthatarecomparabletothisinventory (FebruaryTest4).Increasedpredictedheadlosswillbeexperiencedwhenthe sludge-compactionlimitisproperlyimplemented(possiblybyafactorof2),

sopredictedmaximawillincreaseevenasmeasuredheadlosswouldincrease if"berdebrisvolumeswereincreasedforstrainertesting.Giventhehighper-centilesofDBAtestingwithrespecttothesimulations,itisunlikelythatmore stringenttestconditionswouldchangetheconclusionthatcurrentapplicationof theNUREG/CR-6224correlationprovidesanacceptableenvelopeforpotential headlossacrosstheECCSstrainer.

References:

1.0415-0100069WN/0415-0200069WN,SouthTexasProjectTestReportforECCSStrainerPerformanceTestingFeb2008,RevisionA,11/24/2008.2.0415-0100071WN/0415-0200071WN,SouthTexasProjectTestReportforECCSStrainerPerformanceTestingJuly2008,RevisionA,11/24/2008.2.3.6.29SSIB,HeadLossandChemicalBumpUp:Question 17aSTPResponse:(Item17a,Page73)TheLARisnotattemptingtoapplythecorrelationalonetoqualifyper-formanceofaparticularstrainer,butrather,isusingthecorrelationtoreveal trendsinstrainerperformancethatmaychallengeriskinformedsuccesscriteria.

Thecorrelationaloneisonlyonepartoftheapplication.Theassumptionof fullbedcompressionanduncertaintyfactorof5mustalsobeconsideredpart ofthehead-losspredictionthatcompensatesinpartforsomeofthe complicationswithNUREG/CR-6224.AsnotedinthisRAI,theNUREG/CR-6224correlationhasnotperformedwellformicroporousdebris.However,STPhasasparseamountofmicroporous debristhatdoesnotdominatetheheadlossbehaviorortherisk.Theabsence ofmicroporousdebrisinvalidationtestingisconsistentwithplant-speci"ccon-

ditions.HTVLtestseries2(LAREnclosure4-3,Reference[24])attemptedtorepli-cateARL"umetestingofSTPstrainers(1)usingplant-speci"cdebriscombina-tionsof"berglass,tin,acrylicpowderandchips,Microtherm,MarinateBoard, andlatentdirt/dust.AtSTP,"berglassandunquali"edepoxycoatingsthatare presumedtofailrepresentthedominantconventionaldebristypes.OthertestsintheHTVLtestseries(LAREnclosure4-3,Reference[24])employedalong-standingpracticeofusingsubstituteparticulates.Forexample, acrylicpaintpowderwasusedasasubstituteforfailedepoxycoatingsandsilicon carbidewasusedtorepresentlatentdebris.Substitutionofparticulatesshouldbeacceptableaslongas"owconditionsinternaltothebedcanbeestablishedthatareplantspeci"c.Analternatehead-lossmodelbasedoncorrelationof"owresistancetoReynoldsnumber(Enclosure 1)wascalibratedusingexistingHTVLtestdata.ComparisonofReynolds"owTuesday1 stMarch,2016:19:32,Page313of393 DRAFTPART2.RAIRESPONSES(ROUND1)regimesachievedinthetests(0.2to4.5)to"owregimesextractedfromthepopulationofCASAGrandebedcon"gurationsshowsverygoodagreement.

Additionaldetailofthis"ow-regimecomparisonisprovidedintheresponsesto SSIBRAI15cand17c.

References:

1.0415-0100071WN/0415-0200071WN,SouthTexasProjectTestReportforECCSStrainerTestingJuly2008,RevA,11/24/2008.2.3.6.30SSIB,HeadLossandChemicalBumpUp:Question 17bSTPResponse:(Item17b,Page73)TheUNMverticallooptestingisconsideredtobepartoftheNUREG/CR-6224validationwhichincludedawiderangeofdebrissizesincluding blender-processed"berglass.HTVLtestingconductedatAlionHydraulicsLab-oratoryusedamodi"edNEIdebrispreparation.Therefore,prototypicaldebris sizesareconsideredtobewellrepresented.AsmentionedintheresponsetoSSIBRAI15cexaminationofReynolds"owconditionsshowsthatregimesofinterestidenti"edintheCASAGrandeanalysis spectrumarewellrepresentedbyexistingtestdata.2.3.6.31SSIB,HeadLossandChemicalBumpUp:Question 17cSTPResponse:(Item17c,Page73)SeetheresponsetoSSIBRAI15c.2.3.6.32SSIB,HeadLossandChemicalBumpUp:Question 17dSTPResponse:(Item17d,Page73)Forthepurposeoftherisk-informedLAR,validationtestingincludes:(1)strainertesting,(2)HTVLtesting,and(3)UNMverticalcolumntesting.Strainer testingdidincludeprototypicalSTPgeometry,andoneseriesofHTVLtestswas patternedafterthe"umetestconditions,debristypesanddebrisloading(LAR Enclosure4-3,Reference[24]).2.3.6.33SSIB,HeadLossandChemicalBumpUp:Question 17eSTPResponse:(Item17e,Page73)Forthepurposeoftherisk-informedLAR,validationtestingincludes:(1)strainertesting,(2)HTVLtesting,and(3)UNMverticalcolumntesting.Strainer testingdidincludeprototypicalgeometriesusedatSTP.Whiletruethatvertical looptestingdoesnotincludeallgeometriceconsistentlyuniformdebris bedsaretoformevenundercontrolledtestconditions.Occlusionsand bridgingoftenobservedinstrainerteststendtoadmitmore"owperunitarea andreduceheadloss.Thisisanimportantreasonforconductingcorrelation testingunderverticalloopconditions.Currentstrainertestproceduresemphasize100%debrisloading,soalldebrissizespresentinNEI-preparedtestmaterialisequallyrepresentedinboththe strainerandverticalcolumntestcon"gurations.Small"bermaterialconsistent withNEIdebrispreparationmethodsissimilarlytransportableasthe"nes.Tuesday1 stMarch,2016:19:32,Page314of393 DRAFTPART2.RAIRESPONSES(ROUND1)Ingeneral,uniformbedsconstructedinverticalcolumncon"gurationspro-videamoreconsistentbasisforvalidationandmoreconservativeresultswhen allbedparametersareequal,somorevalidationanalysishasbeendevotedto thesetestconditions.2.3.6.34SSIB,HeadLossandChemicalBumpUp:Question 17fSTPResponse:(Item17f,Page73)Consistentwiththisobservation,con"rmatoryanalysisisprimarilyfocusedonrecentdatasince2010withtdocumentationtodemonstrateappli-cabilitytoplantconditions.ThesupplementaryreportaccompanyingthisRAI response(Enclosure1)presentsanalternativehead-losscorrelationtoprovide perspectiveontheuseofNUREG/CR-6224asimplementedintheLAR.The newmodelhasbeencalibratedandveri"edusingrecenttestdata.2.3.6.35SSIB,HeadLossandChemicalBumpUp:Question 18aSTPResponse:(Item18a,Page73)TheresponsetoSSIBRAI11cprovidesjusti"cationofawell-mixedcon-tainmentpoolandstates,"1.Forallbreaks,theinitialhigh"oorvelocitiesfrom sheeting"owcausedbythepipebreakandcontainmentspraysareexpectedto scatterdebriswithnopreferentialdirectionthroughoutcontainment.2.Finede-briswillbefurthermixedafterrecirculationbecauseofmultidirectionalvelocity vectorsandturbulentkineticenergy."Ahomogeneouslymixedcontainmentpool supportsformationofahomogenousdebrisbed.Also,theassumptionofearly andnearlysimultaneousdebrissourceintroductionfurthersupportsformation ofahomogenousdebrisbed.Oncedebrisarrivesatthestrainer,migrationprocessestendtohomogenizeanystratathatmightinitiallybeformedbysequentialarrival.Particulatemi-grationisclearlyevidentinalltestcon"gurationsasvisiblecloudsofparticulate orchemicalsthatpassthroughthedebris.Whenvisibilityinaverticalcolumn testimprovesthroughcontinued"ltration,itissometimespossibletoobserve particulatemigrationthroughtheedgesofthedebrismat.2.3.6.36SSIB,HeadLossandChemicalBumpUp:Question 18b STP Response:(Item18b,Page315)Toclarifytheimplementationofmanufactureddensity,thevelocityandcom-pressionmodelsmustbeexplainedinfurtherdetail.Thetime-dependentvelocity usedtoevaluatethehead-losscorrelationwasdeterminedbydividingthevolu-metric"owratebythesurfaceareaofanuncompressedbedwithanassumed densityof2.4lb/ft3.Thisassumptioncausesanearliertransitiontothecircum-scribedareaforlargebreakshavingenoughdebristo"llinterstitialstrainergaps thataremostlikelytochallengeplantperformancecriteria.Transitiontocir-cumscribedareacancauseasuddenincreaseinfacevelocityandacorresponding increaseinheadloss.Theintendedtreatmentofbedcompressionwastoevaluateallcaseswithaminimumporosityandminimumbedthicknessde"nedbyamaximumpackingTuesday1 stMarch,2016:19:32,Page315of393 DRAFTPART2.RAIRESPONSES(ROUND1)densityof65lb/ft3.Thisapproachisindependentfromtheassumptionusedtocalculatefacevelocity.Thecurrentquanti"cationdoesnotincludeofthe intendedcompressionlimit.Assuggested,asensitivitytestwasperformedusing thesludgelimitasaplausiblecompressionconditionthatresultedina increasebyafactorof1.8.Thebedcompressioncalculationisbeingrevisedasshownbelow:

Forverylargepressuregradients,thecompressionhastobelimitedsuchthatamaximumsolidityisnotexceeded.InNUREG/CR-6224,thismaximum solidityisde"nedtobe:m=65lbm/ft 3p(Equation38a)Thisisequivalenttohavingadebrislayerwithadensityof65lbm/ft3.Notethat65lbm/ft3isthemacroscopic,orbulkdensityofagranularmediasuchas sandorgravelandclay.Formixed"berandparticulatebeds,thesludgepackingdensityisconsideredtobeconservativelyhighandtheanalogoussoliditylimitis:m=V p+V f V bed=m ff+m pp65lbm/ft 3 m f+m p(Equation38b)wherethesubscriptsreferto:

f,"ber p,particulate and Visthevolume, misthemass, V x=solid"bervolume(f),solidparticulatevolume(p),totalbedvolume(bed), m x="bermass(f),particulatemass(p),x=average"berdensity(f)oraverageparticulatedensity(p).Toavoiditerativesolutionsimpliedbythe"bercompressionformulasthatbothanddependontheheadloss,thehighparticle-to-"berratiolimitfor mixedbedsoliditywasappliedtoallhead-losscalculations.Thecorresponding limitingbedthicknessisfoundbysubstitutingEq.(36)intoEq.(35)andsolving forbedthicknessusingEq.(38b)asthelimitingmixed-bedsolidity;L m=1m1+fp0L 0(Equation38c)2.3.6.37SSIB,HeadLossandChemicalBumpUp:Question 18cSTPResponse:(Item18c,Page73)Presentquanti"cationoftheSTPLARintendedtoimposesludge-limitpack-ingdensityforallcasestoavoiditerativerequirementsoftheNUREG/CR-6224compressionmodel.However,acode-levellogicerrorrevertedallcasesto mixed-bedporositywithoutcompression.Implementationofthesludgelimitas intendedincreasesbyafactorof1.8withallotherinputsequivalentto thebaseline.TheresponseprovidedtoRAISSIB-RAI-18bdescribeshowthe sludgelimitiscalculatedandapplied.TheconditionhasbeenenteredintheSTPcorrectiveactionprogramandtheAlioncorrectiveactionprogram.Tuesday1 stMarch,2016:19:32,Page316of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.38SSIB,HeadLossandChemicalBumpUp:Question 18dSTPResponse:(Item18d,Page74)Thesupplementaryreportpreparedtoaccompanyhead-lossRAIresponses(Enclosure1)illustratesthatlinearvolumeweightingisthepropergeneral treatmentforcompositeaveragingofsurface-to-volumeratio.Massandvolume weightinggiveidenticalresultsintheidealcasewherealldebrisdensitiesare identical.Comparisoncalculationsbetweenthetwomethodsshownosigni"cant increaseinwhenlinearvolumeweightingisappliedwithSTP-speci"c

inputs.2.3.6.39SSIB,HeadLossandChemicalBumpUp:Question 18eSTPResponse:(Item18e,Page74)Packingfractionisdrivenbythegeometryofparticles.Theassumptionthatallcoatingmaterialshaveasimilarpackingfractiontoacryliccoatings(0.39 asdescribedinSTPLAREnclosure4-3,Reference24)isreasonablebecause theconstituentsarecomparableinsize,approximately10microns.Non-coating particulatedebriswasassumedtohaveapackingfractionsimilartoironoxide sludge(0.20).NUREG/CR-6224citesthepackeddensityofironoxidesludgeas 65lb/ft3.PerMarksEngineeringHandbook(1),awetmixtureofclayandsoil alsohasadensityof65lb/ft3.Packingratiosforcoatingsmaterialsarenotuseddirectlyinthehead-losscalculation,sothereisnomeasurableofthisassumptiononresults.Limitedinformationisavailableforpackingratiosofpurecoatingsmaterials,whichiswhydegradedcoatingswereassumedtohavepropertiessimilarto acryliccoatingsthataredescribedinSTPLAREnclosure4-3,Reference24.

Reference:

1.Avallone,E.andTheodore,B.MarksStandardHandbookforMechanicalEngineers.McGraw-HillCompanies,Inc,1999.2.3.6.40SSIB,HeadLossandChemicalBumpUp:Question 19STPResponse:(Item19,Page74)ThehasnotednumeroussensitivitiesoftheNUREG/CR-6224head-losscorrelationtomaterialpropertiesanddebriscon"gurationswithintheporous bed.Residualuncertaintyalsoexistsindataavailabletodescribeproperties andbedcon"gurations.Sensitivitiesanduncertaintiesmayexistregardlessofthe "delityofthepredictivemodel,soitisappropriatetoacknowledgethepossibility ofhigherhead-lossthanindicatedbytheexistingmodel.Thefactorof5(with astandarddeviationof1)isappliedtorepresentpropagationofuncertainty andmodelingsensitivities.STPdoesnotviewthissimplyasasafetyfactor,but ratherasasurrogateenvelopeonvariabilitynotfullyresolvedbythemodel.

STPapplicationoftheNUREG/CR-6224correlationincludestheassumptionof sludge-limitcompactionandthefactorof5uncertaintyenvelope.Whileisolated conditionsmayexistthatcauseNUREG/CR-6224alonetounderestimateheadlossbymorethanafactorof5,itisnotclearthatthoseobservationsincludetheassumptionofsludgecompaction,northeuseofrepresentativedebrismaterial.Tuesday1 stMarch,2016:19:32,Page317of393 DRAFTPART2.RAIRESPONSES(ROUND1)AnalternativecorrelationbasedonReynoldsnumberintheviscoustoinertialsheartransition(VISTA)developedinasupplementaryreport(Enclosure1) illustratesthattheLARassumptionsareconservativeforthepredominant"ow conditionsofinterest.ThestrategyusedtoassureadequacyofSTPLARhead-losspredictionsincludesthreeparts:1)Supplementaryreport(Enclosure1)demonstratestestresultscanbere-producedwithgood"delityusinganindependentphysicalmodelthat addressesknownde"cienciesoftheNUREG/CR-6224correlation,2)Supplementaryreport(Enclosure1)demonstratesavailabletestconditionsspan"owregimesofinterestforSTPandthatrealisticmodelsreproduce themostprevalentconditionswiththehighestaccuracy,3)ResponsetoESGB,ChemicalRAI2demonstratestheLARap-plicationreasonablyboundsavailabletestdata.2.3.6.41SSIB,HeadLossandChemicalBumpUp:Question 20STPResponse:(Item20,Page74)Largemiscellaneousdebris(tags,labels,ties)istreatedbystandardmethodsasadirectreductioninstrainerarea.IntheLAR,paintchipsarecategorizedbystandardsizesandinventoriesforeachsizearedeterminedbyexternalanalysisofboundingbreakconditions.

Largechipsandcurlstypicaloffailedunquali"edcoatingsarenotpresentduring "ll-uptransportandhaveverylowtransportfractionsunderSTPrecirculation conditions,sotheyarenotexpectedtoobstruct"owthroughindividualstrainer openings.Whenlargeparticles(greaterthan10umlargestdimension)arepresentinacompositedebrisbed,they"uid"owthroughtheirtotaldragareajust likeanyotherdebriselement.Althoughbedscomposedentirelyof"akesand chipsorientedperpendiculartothe"owmayhaveauniquebehavior,thereisno reasontosuspectthatrandomlyorientedchipsand"akescannotbemodeledby standardcorrelations.Infact,becauseaveragesurface-to-volumeratiosforlarger debriselementsaresmallcomparedtoverysmallparticulates,thecontribution oflargeparticlesandchipsisoftenignoredintestcon"gurations.ThereisnointentinLAREnclosure4-3,Section5.6.2totreatchipsand"akesassphericalparticles.Whentheoriginalquanti"cationwasperformed, CASAGrandeonlyincludedgeometricsurface-to-volumeratioformulasfor spheres(particulatewhere S sph V=6/dforparticlediameter d)andforforcylin-ders("berswhere S cal V=4/dforparticlediameter d).Inthematerialpropertiestable,arti"cialsphericaldiameterswereintroducedforpaintchipstoensure thatthedesiredsurface-to-volumeratioforchips(S chip V=2 tforthickness t)werepreserved.Equivalentsphericaldiameteriscomputedas d=2 t.Thisisanunnecessarycomplicationoriginallyintroducedforexpediency,butitdoesnot changethefundamentaltreatmentofpaintchipsinthehead-lossevaluation.Tuesday1 stMarch,2016:19:32,Page318of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.42SSIB,HeadLossandChemicalBumpUp:Question 21aSTPResponse:(Item21a,Page74)AsstatedinSection5.6.2ofLAREnclosure4-3,SvvaluesforeachmaterialwerecalculatedbyCylindrically-shapeddebris:

S v=4/diamSpherically-shapeddebris:

S v=6/diamFlakes("at-plates):

S v=2/thickwherediamisthediameterofthe"berorsphericalparticleandthickisthethicknessofthe"ake/chip.Thegeometry,dimensions,andcalculatedSvvalues arepresentedinTables5.6.1and5.6.2ofLAREnclosure4-3.Thebasisofthese tablesisdescribedintheresponsetoSSIBRAI24.Notethat S vvaluesforchipdebriswerecalculatedinCASAGrandewiththesphericalformulausingsubstitutediametersthatproducevaluesequivalent tothe"akethicknessformula(mentionedinthefootnotesonPage179ofLAR Enclosure4-3).2.3.6.43SSIB,HeadLossandChemicalBumpUp:Question 21bSTPResponse:(Item21b,Page75)

The S vvaluesforindividualmaterialsweredeterminedusingcharacteristicdiametersinstandardgeometricformulasasshownintheresponsetoSSIBRAI 21a.ThebasisforthediametersusedisdisplayedintheresponsetoSSIBRAI 24.Basesformaterialdensities(microscopic)areprovidedinreferencestoLAR Enclosure4-3Table2.2.21.STPdoesnotagreethatphysicalmeasurementsofmaterialpropertiespre-cludeaccuratepredictionofheadloss.Ingeneral,independentmeasurements ofpropertiesandfreeparametersareessentialtovalidatethetheoreticalbasis ofanypredictivemodel.Thesupplementalreport(Enclosure1)illustrateshow measuredvaluescanbeusedtocalibrateanalternativehead-lossmodelthat reproducestialpressurehistorieswithgood"delity.2.3.6.44SSIB,HeadLossandChemicalBumpUp:Question 21cSTPResponse:(Item21c,Page75)UncertaintycausedbytherelationshipbetweenexperimentallydeducedSvandheadlossestimatesisdiscussedinLAREnclosure4-3asacautionarynote againstindiscriminantapplicationofdebrispropertiesmeasuredinthismanner.

Whenatheoreticalformulationisusedtoextractbedproperties,thespeci"c numericvaluesobtainedaretiedtotheaccuracyoftheformulaitself.Anin-herentpartofphysicsmodelsisthatanyinaccuraciesintheexplicitfactors(or form)ofamodelarerelegatedtothevaluesoffree(orunknown)parametersin themodel.Itisbettertodeterminematerialpropertiesandotherparameters independentlyifpossible.TheexampleexplainedinLAREnclosure3withrespecttoironoxideSvisagoodexampleofcon"rmationbycomparison.Surface-to-volumeratiowas usedlikeafreeparameterto"rstachievegoodagreementwiththepressuredrop measurements.ThecorrespondingsphericalparticlesizewasthencomparedtoTuesday1 stMarch,2016:19:32,Page319of393 DRAFTPART2.RAIRESPONSES(ROUND1)descriptionsofthebulkparticulatetocon"rmthatthenominalparticlesizewassimilar.AlldebrisSvusedintheLARarebasedongeometricapproximations ratherthanonexperimentallydeterminedvalues.Thus,thisformofpropagated uncertaintyisnotaconcernfortheanalysis.Inaccuracyinthegeometricap-proximationiscoveredbythefactorof5uncertaintyboundasdiscussedinthe responsetoSSIBRAI19.2.3.6.45SSIB,HeadLossandChemicalBumpUp:Question 21dSTPResponse:(Item21d,Page75)OneoftheencounteredinverticalheadlosstestingwithNEIprepared"berglassisachievingcomplete"ltrationofparticulatethatisintro-duced.Theratioofparticulateto"berresidentinthebedcalculation ofthecompositeporosity.Itisgenerallyconservativetoassumecomplete"l-trationsothatthein"uenceofdebrisonheadlossismaximized.Assumption ofcomplete"ltrationpartiallyexplainswhymeasuredheadlosseswereoveres-timatedbycalculation.AlthoughSTPdoesnothavethesurrogatematerials ofsiliconcarbideandtinpresentinthedebrisinventory,iftheywerepresent, useofthecorrelationinitspresentformwouldleadtoconservativeestimatesof headlossimpact.Similaroverestimationwouldbeobtainedforanyparticulates havingsimilarmaterialpropertiesandbeingresidentinsimilarquantities.In thissense,lackofpreciseagreementbetweentestandcalculationdoesnot theconclusionsoftheriskquanti"cation.ThesupplementarywhitepaperaccompanyingtheseRAIresponses(Enclo-sure1)providesvisualSEMcomparisonsofprototypicaldebristypesthatwere tested.Directmeasurementsofspeci"csurfaceareaforsiliconcarbide,acrylic coating,and"berglassareusedtodemonstrateagreementofanalternatehead-losscorrelationwithTests4and6thatweredescribedaschallenginginRefer-ence24ofLAREncl.4-3.Head-losspredictedbyconventionalimplementation of6224consistentlyoverestimatedvaluesmeasuredforTests1-4thatcontained low-density"berglassandsiliconcarbide.Goodpredictiveagreementwithtest datausinganindependentmodelprovidescon"dencethattheSTPLARappli-cationofNUREG/CR-6224(including5timesuncertaintyfactorandfullbed compression)doesnotunderpredict"owconditionsofinterest.2.3.6.46SSIB,HeadLossandChemicalBumpUp:Question 22STPResponse:(Item22,Page75)STPdoesnotagreethatobservationscitedinthisRAIaregenerallyappli-cabletoallcorrelationssimilartoNUREG/CR-6224.Independentcon"rmation ofthesurface-to-volumeratiofor"berglasssuggeststhatnocompensationis needed.Uncertaintiesinparticulatepropertiesthathavenotbeencon"rmedare addressedbythefactorof5uncertaintyboundappliedtoallpredictionsofthe model.Asexplainedinthewhitepaperaccompanyingthisresponse(Enclosure 1),thederivationoftheErgunequationandtheNUREG/CR-6224variantis basedonahydraulicscalingargumentthatdependsonthetotallocaldragarea andnotontheorientationofthedebriselements.Forexample,thecylindrical surface-to-volumeratioisapproximatedas S v=(h)/( 2 h/4)=4/d forTuesday1 stMarch,2016:19:32,Page320of393 DRAFTPART2.RAIRESPONSES(ROUND1)cylindricaldiameter dandlength h,wheretheverysmallfaceareaofthecylin-derendsisignored.Thepossibleinterpretationofcylindricalsurface-to-volume ratioasaratioofperpendicularperimetertoperpendicularareaisincomplete.Asamanufacturedproduct,"berglassdoeshavearelativelyuniformdi-ametercomparedtoirregularparticulatedistributions.Directmeasurementof speci"csurfaceareaforclean"berglassincombinationwithanassumedmate-rialdensityof2.8g/cm3(175lbm/ft3)givesasurface-to-volumeratioof594,282

m1,whichis4%higherthanthestandardassumptionof571,429m1obtainedbygeometricapproximationfora7

µmcylinder.TheslightlyhighermeasuredvaluecanbeattributedtothepresenceofbinderasnotedintheRAIstatement.

Independentcon"rmationofanimportantmaterialpropertyforoneofthedom-inantdebristypeslendscon"dencetouseofthegeometricapproximationfor "berglassinallapplicationsofNUREG/CR-6224foundintheLAR.AsdiscussedintheresponsetoSSIBRAI21c,adjustmentstofreeparame-tersbasedonagreementofamodelwithdatainherentlydependontheaccuracy andformofthemodelitself.Afterlonguse,certainconventionsbecomeembed-dedinthequanti"cationofimportantproperties;forexample,thefactorization of(1/2) 2inparticulatedragcots.However,itispreferabletohavein-dependentmeasurementsofkeyparametersthatdonotdependontheinherent accuracyofthetheoreticalmodel.Thewhitepapersupplementtothisresponse (Enclosure1)providesanexampleofmodelcalibrationusingindependently measuredmaterialproperties.2.3.6.47SSIB,HeadLossandChemicalBumpUp:Question 23STPResponse:(Item23,Page75)MaterialpropertiesofMicrothermwereprimarilytakenfromLAREnclosure4-3,Refeence[43,AttachmentE].ThereferencestatesthatMicrotherm"bers areglass"lamentsthatare6microns(6*10-6m)indiameterandhaveaspeci"c gravityof2.65.Usingtheaveragesurfacetovolumeratioequation(S v=4/diam),thesurface-to-volumeratiowascalculatedtobe666,667m 1.Usingthedensityofwateras62.43lb/ft3andtheequationSG microtherm

=Density microtherm

/Densitywater,themicroscopicdensityofMicrothermwascal-culatedtobe165lb/ft3.Microthermwassplitupintoitsconstituents("ber, SiO 2andTiO 2)tosimplifycharacterization.LAREnclosure4-3assumedthatMicrotherm"bersbulkdensityisthesameaslowdensity"berglass(LDFG) bulkdensity.2.4lb/ft3,thebulkdensityforLDFG,isareasonablevalueforthe bulkdensityofMicrotherm"berbecauseMicrotherm"berhasthesameshape andasimilarmicroscopicdensityand"berdiameterasLDFG.ResponsestoSSIBRAIs18band18cexplainmorecompletelytheuseofNukon"berbulkdensityforcalculatingthedebrisbedsurfacearea.Ingeneral, asludgecompactionlimitwasintendedforalldebrispackingdensitiessothat minimumthicknessisusedinthehead-losscalculations.2.3.6.48SSIB,HeadLossandChemicalBumpUp:Question 24STPResponse:(Item24,Page76)Tuesday1 stMarch,2016:19:32,Page321of393 DRAFTPART2.RAIRESPONSES(ROUND1)AsexplainedinresponsetoSSIBRAI21a,standardgeometricformulaswereusedtocalculatesurface-to-volumeratiosSvusingnominalrepresentativedebris sizes(radiiforcylindersandspheres,thicknessforchips).Characteristicvalues providedinSTPLAREnclosure4-3,Tables5.6.1and5.6.2arebasedlargelyon manufacturerandsupplierinformationdataaswellasondeterministicguidance referencedinexplanationofSTPLAREnclosure4-3,Table2.2.21.Thefollowing excerptcitesrelevantreferencesfromSTPLAREnclosure4-3:Table2.2.21providesthematerialproperties(sizeanddensity)forinsula-tion(43;46;45),quali"edcoatings(11;43),unquali"edcoatings(12),crud(13),

andlatentdebris(43)atSTP.Materialdensitiesbasedonmanufacturerspeci"cationsshouldbeaccuratetobetterthan

+/-10%.Cruddensitywasintentionallyselectedfromthelowerendofarange(350Ibm/ft3fromarangeof325to556lbm/ft3)leavinganasym-metricuncertaintybandof-1%to+60%.Lowermaterialdensityisconsidered conservativebecausetheparticulatetakesupmorespaceinsideofthedebris bedreducingporosityforagivencompactionratio.De"nitionofreasonableuncertaintybandsforconstituentsurface-to-volumeratioequatestode"ningreasonableuncertaintybandsonnominalsize.Ingen-eral,smallerparticlesizesleadtohigherheadlossandincreasedrisk,asdemon-stratedintheexamplebelow.Itshouldbenotedthat"berglass,beingamanu-facturedproductthatformsthedominantsubstrateforalldebrisbedsatSTP, hasaveryregulargeometryanddensity.Theassumed7-

µm"berdiameteriscon"rmedbySEMimagesandbydirectmeasurementof S v(Enclosure1),whichagreeswithin4%ofthegeometricapproximation.Uncertaintyrangesonthenominalsizeofotherconstituentsvary.Acruddiameterof15 mumwaschosenfromarangeof8to63 mum,leavinganasym-metricuncertaintyrangeof-47%and+320%.Failedunquali"edcoatingswere assignedasizeof10 mumfromarangeof4to20 mum,leavinganasymmetricuncertaintyrangeof-60%to+100%.Ofcourse,theremayberesidualuncer-taintiespresentinthede"nedrangesanduncertaintiesinthedistributionof particulatesacrossthestatedranges,conservatismwasintroducedbyselection ofsmallersizes(pointvaluesthatrepresentanentiredistribution)thanwould bepresentusingacompletewell-de"neddistributionofparticlesizesforeach constituent.Particlesize,andhence S v,wereintentionallynotselectedasran-domvariablesintheCASAGrandesamplematrixbecauseagreaterdegreeofconsensussupportstheadoptionofpointvaluesthanexistsforotherimportant parameters.Toinvestigatehowcompoundedinaccuraciesinassumedmaterialpropertiesmighthead-lossvaluespredictedbythecorrelation,aparameterstudywas performedwherealldebrisdiameterswerearti"ciallyincreasedby30%,causing a25%decreaseinAsimilarglobal30%decreaseindebrisdiameters causeda40%increaseinThe30%degreeofvariationinthiscasestudy representsasubstantialfractionofthereasonableuncertaintyrangesde"ned aboveforimportantparticulates,andimpactsoflessthan50%wereexperienced fromvariationsinsizecompoundedoveralldebristypes.Tuesday1 stMarch,2016:19:32,Page322of393 DRAFTPART2.RAIRESPONSES(ROUND1)2.3.6.49SSIB,HeadLossandChemicalBumpUp:Question 27STPResponse:(Item27,Page77)Thecleanstrainerheadloss(CSHL)valueusedintheSTPCASAGrandeevaluationof0.220ftofH20wasreferencedfrom"SouthTexasProjectTest ReportforECCSStrainerPerformanceTesting"(LAREncl.4-3,Ref.53,Pg.39).

ThisCSHLvaluewasmeasureddirectlyfromthesingle-moduleheadlosstesting performedwithmaximum"owat116F,anddidnotincludethecalculatedeofincreasedheadlossesfortheentirestrainerassembly.TheCSHLvalueof1.952 ftofH20wascalculatedinPerformanceContracting,INCcalculationClean HeadLoss-SouthTexasProjectUnits1&2(Enclosure1)usingconservativeassumptions.TheCSHLvalueof1.952ftofH20giveninthecleanstrainerhead losscalculationwascalculatedunderthefollowingassumptions:

• Totallossescalculatedforthebounding6-moduleSTPstrainerassembly(allothershavefewermodules),*Nocredittakenforexpansionlosses(expansionfactor=1.0),*10%additionalheadlossaddedexpansionfactor,*6%conservatismaddedforcoretubelosses,*Valuecalculatedformaximum"owvelocityandmaximum(6)strainerstringatatemperatureof128F.Thetestedsingle-moduleCSHLvalue(LAREncl.4-3,Ref.53,Pg.39)of0.22ftofH20wasinadvertentlyusedastheCSHLvalueforthetotalassembly inSTPCASAGrandeevaluation.UsingthePCIcalculatedvalueof1.952ftof H20wouldincreasethetotalchangeincoredamagefrequency(value byapproximately18%fromthesubmittalcalculatedACDF.Thisinputerrorto theCASAGrandeevaluationisbeingtrackedundertheSTPcorrectiveaction programandtheAlioncorrectiveactionprogramtoassurethatamoreaccurate CSHLisincorporatedintheanalysisandprovidedinfuturesubmittals.

References 1.SouthTexasNuclearOperatingCompany,CleanHeadLoss-SouthTexasProjectUnits1&2(0415-0100055WN/0415-0200053WN),20062.3.6.50SSIB,HeadLossandChemicalBumpUp:Question 28STPResponse:(Item28,Page77)Useofahead-losscorrelationisessentialtotherisk-informedresolutionpro-cessbecauseitilluminatessubtleinteractionsbetweendebristypes,sourcetim-ing,operational"owrates,andtemperaturehistoriesthatwouldnototherwise beapparentusingengineeringjudgmentalone.Withoutaplausiblyrealisticcor-relation,itwouldbeimpossibletoask/answerquestionsabouttheimplications ofoverallparameterandmodelinguncertainty.Threekeyuncertaintiesresideintheapplicationofahead-lossmodel:(1)formofthemodelneededtocapturerelevantphysicsofhydraulicresistance,(2)Tuesday1 stMarch,2016:19:32,Page323of393 DRAFTPART2.RAIRESPONSES(ROUND1)materialpropertiesneededtodescribecontributionsofindividualdebriscon-stituents,and(3)bedcompression(eitheruniformornon-uniform)thatcontrols porosity.ResponsestootherRAIshaveaddressedeachtopicseparately,butthe aggregateapproachtouncertaintyinhead-losspredictionincludesthefollowing elements:(1)CompareperformanceofNUREG/CR-6224toanindependentlyderivedmodelandcomparebothtotestdatatodemonstrateconservativeperfor-manceofNUREG/CR-6224asappliedintheSTPLAR;(2)Interpretthefactorof5asanuncertaintyboundthatcoversinaccuraciesinindividualmaterialpropertiesandchemical(3)Applyasludgecompressionlimittoobviateconcernsaboutnon-uniformbedresponse.Whilethislimitmayultimatelyprovetobeoverlyrestrictive, itestablishesaboundonpossiblein"uencecausedbybedmechanics.OveralluncertaintieshavebeenaddressedintheSTPLARbysensitivitystudiesthatinterrogatethedegreeofin"uenceonintroducedbychanges inspeci"cparameters(Enclosure2).Theinteractionsofmaterialpropertiesare complexbecauseoftheircontributionstoweightedaveragebedpropertiesand canleadtonon-intuitiveresultsthatbothincreaseordecreaserisksomewhat.

ThesupplementalwhitepaperaccompanyingthisRAIresponse(Enclosure1) discussesonesuchparameterstudytheamountofepoxy"nematerial appearinginthepool.ThisperturbationdecreasedCDFbynomorethan10%.

Inoneparameterstudyperformedtosupportthisresponse,alldebrisdiameters werearti"ciallyincreasedby30%causinga25%decreaseinAsimilar global30%decreaseindebrisdiameterscauseda40%increaseinNote thatchangesindebrisdiametersimplydirectchangesintheassumedsurface-to-volumeratios S v.Parametervariationstudiesperformedthusfarlendcon"dencethatthefactorof5uncertaintyboundappliedtoallpressuredropcalculations istly,yetreasonably,conservative.Inthisapplication,thefactorof5is analogoustoasingle-sidedparametervariationthatcausesauniformshiftto higherheadloss.Becausethex5uncertaintyboundrepresentsanenvelopeofpotentialthatarenotfullyresolvedinthevalidationtests,asensitivitystudywasrunon thisfactorkeepingallotherinputsequaltothebaseline.Beingasimplemultiple onconventionalheadloss,changestothisparametercanbeviewedasshifting theentiredistributionofpredictedheadlossupordownrelativetothestrainer-relatedperformancecriteriaofNPSH,bucklinganddegasi"cation.The ofshiftingtheuncertaintyboundalongarangefrom1to7,whenappliedasa precisevaluewithnostandarddeviation,isillustratedinFig.A.Thein"uenceof thisparameteronCDFisnearlylinearintheregionabout5.0.Notethatthe baselinequanti"cationincludesastandarddeviationof1aboutameanfactor of5.Thisspreadallowsslightlymorecasestofailthanasharpvalueof5sothe ratioofriskatthisvalueislessthan1.0.2.3.6.51SSIB,NPSHandDegasi"cation:Question33 STPResponse:(Item33,Page78)Tuesday1 stMarch,2016:19:32,Page324of393 DRAFTPART2.RAIRESPONSES(ROUND1)FigureA:SensitivityofCDFtochangesinhead-lossuncertaintyboundpresentedasaratiotothebaselineThepoolwaterlevelwascalculatedusingEquation1ofLAREnclosure4-3,Rev.2inSection2.2.5usingthe"oorareaatthebottomofthepool.This standardpracticeofusingthe"oorareaatthebottomofthepooldoesnot accountforchangesinpoollevelwithelevationorchangesinobjectsthatmay displacewater.ACADcalculationwasperformedinsupportofthisresponsetocalculatepoollevelsasafunctionofwatervolumewithdisplacementfromequipment included.AcomparisonoftheCADandCASAGrandepoolelevationsare shownbelow.Aspoollevelsincrease,CASAGrandeoverestimates(ishigher than)thepoollevelwithrespecttotheCADdeterminedlevel.ThemaximumandaveragebetweenthehigherCASAGrandeelevationsandthelowerCADelevationsare7.0and5.1inches(10.6%and 9.8%)respectively.Theelevationswereevaluatedbetweentheminimumand maximumSTPpoolvolumes(LAREnclosure4-3,Pg.45).ThereisaninconsistencybetweenthelevelscalculatedusingthereferencedpoolareaandthecurrentlyQAapprovedCADmodelcalculatedlevels.This errorwillbetrackedintheSTPcorrectiveactionprogramandchangeswill bemadeinanyfuturesubmittalswhichwillincludeusingCADelevationsto determinepoollevels.2.3.6.52SSIB,NPSHandDegasi"cation:Question36 STPResponse:(Item36,Page78)ThebasisforthevaluesusedinLAREncl.4-3istheoperationandmain-tenancemanual(2and3)whichprovidetheNPSHrequiredatthepump"rst stageimpeller.Thiswasdeterminedbypumptestingandismetbythepump barreldesignwhichhasaheightof15ft.Table1displaystheNPSHrequiredatthepumpimpellerforeachpumpatthespeci"ed"owrate.However,verticalcentrifugalpumpshavetwoindependentNPSHrequiredTuesday1 stMarch,2016:19:32,Page325of393 DRAFTPART2.RAIRESPONSES(ROUND1)Figure2:ComparisonofCADandCASAGrandepoolelevationsversuswatervolumeTable1:NPSHRequiredatthePumpImpellerPumpFlowRate,gpmNPSHRequiredatthePumpImpeller,ftLHSI2,80013HHSI1,62011 CS2,70012values:1)atthe"rststageimpeller(describedabove)and2)atthepumpsuction nozzlelocatedatthetopofthepumpbarrel(1).WhiletheNPSHrequiredat thepumpimpellerisdeterminedbytesting,theNPSHrequiredatthepump suctionnozzleisequaltothevelocityheadatthetopofthesuctionnozzle(1) aspresentedbyEq1.NPSH R@suct=v 2 2 g+1 2 d(Eq1)Table2displaystheNPSHrequiredatthepumpsuctionnozzleforeachpumpatthespeci"ed"owrate.Table2:NPSHRequiredatthePumpSuctionNozzlePumpFlowRate,gpmNPSHRequiredatthePumpSuctionInlet,ftLHSI2,8001.5HHSI1,6201.1 CS2,7001.4LAREncl.4-3onlydeterminedtheNPSHmarginatthepumpimpeller.ACASAGrandeparameterstudywasconductedwheretheNPSHmarginwas calculatedatthepumpsuctionnozzle.Althoughthisinputcausedanetre-Tuesday1 stMarch,2016:19:32,Page326of393 DRAFTPART2.RAIRESPONSES(ROUND1)ductioninNPSHmargin,theACDFdidnotchangebecausestrainerbucklingisthelimitingfailurecriterion.Inotherwords,thenumberoffailuresdidnot changebecauseadditionalfailurescausedbytherevisedNPSHtreatmentwere alreadyfailingthestrainerbucklingcriterioninLAREncl.4-3.Theresponse toESGBRAI17intheSTPletterprovidedtotheNRCdatedJune25, 2014,NOC-AE-14003101,ML14178A481andML14178A485furthersupports thisobservationbystating:Achemicalhead-lossfactorof43wouldleadtobucklingfailureofthestrainerforallsimulatedbreaksinCase01,fulltrainoperation.

Achemicalhead-lossfactorof209wouldleadtotheviolationofthe NPSHmargincriterionandfailureforallsimulatedbreaksinCase 01,fulltrainoperation.EventhoughthecorrectionoftheNPSHevaluationwillhavenoontheconclusionsintheLAR,itisstillbeingtrackedintheAlioncorrectiveaction program.TheSTPUFSARalsorequiresclari"cationandtheconditionhasbeen loggedintotheSTPCorrectiveActionProgram.

References:

1.ST-WN-YB-1883.WestinghouseElectricCorporationLetter.8/29/1985.

2.VTD-P025-0001.LowHeadSafetyInjectionandContainmentSprayPumpsOperationandMaintenanceManual.Revision4.11/30/2004.3.VTD-P025-0004.HighHeadSafetyInjectionPumpOperationandMain-tenanceManual.Revision4.1/10/2007.2.3.6.53SSIB,NPSHandDegasi"cation:Question38 STPResponse:(Item38,Page79)No.Thefractionofdebristhatissheddableisnotdependentontheamountofdebrisonthebed.Thefractionofdebristhatissheddableisaconstantfor eachscenariothatissampledfromvariationsinobserveddata(LAREnclosure 4-3,Reference[28],Page.5).2.3.6.54SSIB,DefenseInDepthandMitigativeMeasures:Question 40STPResponse:(Item40,Page80)RegardingfailurethatmayoccurQuantitativeevaluationsofthedefenseindepthandsafetymarginasde-scribedintheLARshowthatpeakcladtemperatureremainsbelow800Fwith asinglefuelchannelunblockedorwith"owthroughthecorebypassthathas largeopeningsunlikelytoretaindebris.Thequantitativethresholdsofconcern usedforsuccesscriteria(forexample,7.5g/FAforcoreblockageorboricacid precipitationstrainerandnocreditforcontainmentoverpressure)supportasser-tionsmaderegardingtherequirementsinRG1.174.Althoughchemicalcorrosion areincludedaspartoftheengineeringsupportfortheriskanalysis,many experimentsperformedwithrealisticpost-LOCAexposuretopossibleprecipi-tateformationshowthatchemicalprecipitatesareunlikelytocausethehead lossesincludedintheLARsupportingengineeringanalyses(LAREnclosure4-3).TheRG1.174analysisdemonstratestheriskisverysmallandthereforetheTuesday1 stMarch,2016:19:32,Page327of393 DRAFTPART2.RAIRESPONSES(ROUND1)functionality,reliability,andavailabilityoftheECCSandCSSremainaccept-able.RegardingdefenseindepthDefenseindepthisprimarilyfocusedontheECCSfunctionsastheyrelatetocorecooling.TheconcernsrelatedtoGSI-191infactdonotbearoncontain-mentintegrityascontainmentcoolingisbythereactorcontainmentfancoolers, systemscompletelyindependentfromtheECCS.Infactthereisnoincreased likelihoodforcontainmentbreachfromtheconcernsrelatedtoGSI-191.This mayseemcounterintuitiveinlightofthe(verysmall)increaseinLERFfrom 8.6E-12/yrto1.40E-11/yrdocumentedintheLAR,page2of5.Thisincreaseis relatedtothefactthatthePRAanalyzescaseswhen,forexample,containment purgeisinprogressandcantbeisolatedwhenacoredamageeventoccurs.Since thereisaverysmallincreaseincoredamagefrequencyanalyzed,thisresultsin thesmallincreaseinLERF.TheLAREnclosure4-1,PartI,ProceduresandActivitiesintheLicensingBasis(startingonpage1)describesechangesinoperation,processes, procedures,anddesignthathavebeeneitherundertakenorstrengthened,or identi"edassupportingabalancedapproachtotheconcernsraisedinGSI-191.

Themostimportantamongthesewastheintroductionofstrainerscapableof withstandinglargedebrisloadsthatmayresultinthehypotheticalLOCAsce-nariosanalyzedinrelationtoGSI-191.Inaddition(describedaswellinPartI),

thedesignprocesshasbeenstrengthenedtopreventintroductionofpotentially harmfulproductsinthecontainmentbuilding,largetransitionweldssusceptible toPWSCCinareaswheremaximumtargetmaterialispresenthaveeitherbeen replacedormitigatedaccordingmodernindustrystandards.Thesteamgenera-tornozzleweldswerereplacedwithAlloy690whenthesteamgeneratorswere replaced,andthepressurizersafe-endweldshavebeenoverlaid.Thereactor vesselnozzlesarestillAlloy600,however,thereactorvesselusesstainlesssteel re"ectivemetalinsulationwhichisnotasumpdebrisconcern.TheregulatoryframeworkfortheSTPlicensingapplicationistoapplyarisk-informedanalysistodemonstratethattheeofdebrisonthesystemsthat supportthelong-termcoolingfunction(i.e.,ECCSandCSS)areacceptably smallandthosesystemsremainreliabletoperformtheirdesignfunction.EventhedeterministicapproachinvolvestheECCSdesignmeetingahighlevelofprobabilitythatECCSperformancecriteriawillnotbeexceeded.Forex-ample,95%probabilityinRegulatoryGuide1.157BestEstimateCalculationsofEmergencyCoreCoolingSystemPerformanceaddressesarelativelynarrow scopeofparametersthatcouldECCSperformance.Therisk-informedap-proachmakesnounconditionalassumptionsrelatedtosuccessandquanti"esa realisticcon"dencelevel.Therealisticriskforlossoflongtermcoolingiseval-uatedtobe"verysmall"intheexistingplantdesigninaccordancewiththe guidanceprovidedinRG1.174,whichcouldbeconsideredequivalenttoahigh levelofprobability.RegardingthehypotheticalcleanplantThehypotheticalcleanplantisdescribedinEnclosure1totheLARandisaplantthathasnosourcesofdebristhatwouldresultintheconcernsrelatedto GSI-191.Theas-built,as-operatedplanthas"brousinsulationthatisthesource oftheconcernsrelatedtoGSI-191.TherearematerialsincludedinthedesignTuesday1 stMarch,2016:19:32,Page328of393 DRAFTPART2.RAIRESPONSES(ROUND1)thatmayinteractwith"brousdebris(includinglatentdebris)toadverselyheadlossand"owtothecore.RegardingequipmentchangesTherearenoproposedchangestohowanyequipmentisoperatedormain-tainedintheSTPapplication;consequently,nochangesareproposedintheLAR toequipmentavailability,functionality,orreliability.AsdescribedintheLAR, Enclosure2-1,Section1,STPNOCrequestsanexemptioninordertoenable theuseofarisk-informedmethodtodemonstrateacceptablesumpperformance andtovalidateassumptionsintheEmergencyCoreCoolingSystem(ECCS) evaluationmodel.2.3.6.55SSIB,DefenseInDepthandMitigativeMeasures:Question 42STPResponse:(Item42,Page81)TheeenessofmitigativemeasuresasdirectedbytheEOPsandSAMGsforinadequatereactorcore"owhasbeenevaluatedaspartofthedevelopment oftheproceduresandguidelines.NotallactionslistedinLAREnclosure4-1AppendixC,Section5.8requireuseofblocked"owpaths.Ifthecoreandcorebypassarebothblockedduring hypothesizedmediumorlargecoldlegbreakscenarios,transfertohotlegrecir-culationwouldbeeeincontinuingtocoolthecore.Forhypothesizedhot legbreakscenarios,orsmallcoldlegbreakscenarioswithcoreblockage,thecold leginjectionpathisallthatisrequiredasdescribedintheLAREnclosure4.3, Section5.10.2.Inadditiontotransfertohotlegrecirculationforthemedium andlargecoldlegbreakscenarioswithfullcoreandbypassblockage,theEOPs requirerunningreactorcoolantpumpsinresponsetoinadequatecorecooling.

Thereactorcoolantpumpdischargepressureofapproximately76psid(1)would beexpectedtocleardebrisorre-"oodthecore.Alternatively,iftheECCS"owpathisblocked,alternatesuccesspathsareprovidedindependentofcoreblockage.Chargingmayberestoredthrougheither thenormalcharging"owpath(viathevolumecontroltank)orthroughthe positivedisplacementpump.TheRWSTmaybeusedfollowingre"llabovethe EMPTYlevel.ThereisnoprocedureforbackwashingthestrainersatSTP.

Reference:

1.STPlettertoUSNRCdatedApril8,2014STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.July2013,ML14091A452Tuesday1 stMarch,2016:19:32,Page329of393 DRAFTPart3ResponsetoEPNBConsistencyofWeldFre-quencieswithRI-ISIProgram:RAI6Weinvestigatethediscrepancyinthefrequenciesofsmall,medium,andlargebreaksbetween:(i)NUREG-1829sTregoningetal.(2008) meanfrequencies,whichareusedinSTPssubmittal,and(ii)the pointestimatesderiveddirectlyfromRI-ISIvaluesFlemingetal.

(2011).Wefurtherdiscussthediscrepancyintheconditionalproba-bilitydistribution(giventhatabreakoccurred)governingbreaksize andweldcaseusing:(i)thesubmittalshybridapproach

?,which"tsJohnsondistributionstoNUREG-1829Tregoningetal.(2008) percentilesandusesRI-ISI,and(ii)onlytheRI-ISIpointestimates.(ENCLOSURE1)ResponsetoEPNBConsistencyofWeldFrequencieswithRI-ISIProgram:RAI6JeremyTejada,JohnHasenbein,andDavidMortonTheUniversityofTexasatAustin3.1EPNBConsistencyofWeldFrequencieswithRI-ISIPro-gram:RAI6ThestatementoftheEPNBConsistencyofWeldFrequencieswithRI-ISIPro-gram:RAI6isasfollows:ByletterdatedSeptember10,2012,theNRCapprovedtherisk-informedinserviceinspection(RI-ISI)programforthethird10-year inserviceinspectionintervalatSTP,Units1and2(ADAMSAcces-sionNo.ML12243A343).Pleasediscussthefollowing:A)PleasestateiftheLOCAfrequencyestimatesusedforweldsintheGSI-191submittalareconsistentwiththeLOCAfrequencyestimates usedintheRI-ISIprogram.Ifthecomparisonisappropriate,please providenumericalexamplesofthecomparison.Ifthecomparisonis notappropriate,pleaseprovideexplanation.B)IftheLOCAfrequenciesforweldsarenotconsistentbetweenthetwoanalyses,(1)pleaseidentifythedandexplainwhythere areand(2)pleasediscusswhytheLOCAfrequencies 330 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6proposedintheGSI-191submittalareacceptableiftheyarenotconsistentwiththatoftheRI-ISIprogram.3.2ConsistencyofLOCAFrequencyEstimates:GSI-191Sub-mittalandRI-ISITheLOCAfrequencyestimatesusedforweldsinSTPsGSI-191submittalarenotconsistentwiththeLOCAfrequencyestimatesusedintheRI-ISIanalysis.

STPsGSI-191submittalusesahybridapproachdetailedinPanetal.

?,whichcombinesinformationfromtheRI-ISIanalysisFlemingetal.(2011)(plant-speci"cinformation)withtheLOCAfrequenciesinNUREG-1829Tregoning etal.(2008)("eet-wideinformation).Thislackofconsistencyinouranalysisisbydesign.Speci"cally,wemaintainconsistencywithNUREG-1829frequenciesforpiperupturesatvariousbreak sizes,andatthesametime,weuseplant-speci"cinformationFlemingetal.

(2011)todistributethesefrequenciesacrossweldcaseswithinabreaksize.We seeourapproachasconsistentwiththeNRCscommentsUhle(2005)onthe analysisofHochreiter(2005).TheanalysesofFlemingetal.(2011)andHochre-iter(2005)aresimilarinthattheyemployinformationregardingafrequencyof degradationratherthanafrequencyofpiperupture.WeseetheRI-ISIanaly-sisFlemingetal.(2011)ashavingvalueininformingtheconditionalprobability ofpiperupturewithinabreaksize,butweusetheexpertelicitationTregoning etal.(2008),whichfocusedonpiperuptures,toinformfrequenciesofbreaks acrossbreaksizes.Forthereasonsjustdiscussed,wedonotseeanumericalcomparisonasnecessarilyappropriate.Thatsaid,inrespondingtoB)wedoprovideanumerical comparisonofthetwoapproachesvia:(i)themeanfrequenciesofsmall(0.5-inch to2-inch),medium(2-inchto6-inch),andlarge(6-inchandgreater)breaksused inSTPsPRA,and(ii)thejointprobabilityofbreaksizeandweldcase,given thatthereisabreak.3.3EstimateofCDFOurpointestimateofCDFinformsatwo-partanalysisinthisdocument.WeestimateCDFasfollows:CDF=f SL*P (FailurelSL)+f ML*P (FailurelML)+f LL*P (FailurelLL).(Eq1)Here, SL , ML,and LLdenotetheeventsofasmall,medium,orlargebreak,and f SL , f ML,and f LLdenotecorrespondingmeanfrequenciesineventsperyear.AGSI-191failureevent,whetherinthesumporvessel,isdenotedFailure ,andthecorresponding PtermsareconditionalprobabilitiesestimatedusingtheCASAGrandesimulationmodel.Therespectivefrequenciesofasmall,medium,andlargebreak(f SL , f ML , and f LL)usedinSTPssubmittalarereportedinVolume2sTable4-1Wake"eldandJohnson(2013),andmatchlinearlyinterpolatedmeanfrequenciesfrom Table7.19(current-dayvalues)ofNUREG-1829Tregoningetal.(2008),atleast whenweformtocomputewithin-binfrequencies.InSection3.4,weTuesday1 stMarch,2016:19:32,Page331of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6comparethefrequencies, f SL , f ML,and f LL,basedonNUREG-1829meansandbasedonpointestimatesfromtheRI-ISIanalysisFlemingetal.(2011).STPssubmittalfurtherusesahybridapproach

?,which"tsJohnsondistri-butionsto NUREG-1829Tregoningetal.(2008)percentilesandthenusespointestimates fromtheRI-ISIanalysisFlemingetal.(2011)toconstructajointprobability distributiongoverningbreaksizeandweldcase.GiventhatwehaveaLOCA event,thisjointdistributionisusedintheCASAGrandesimulationmodelto formthethreeestimatesoftheconditionalfailureprobabilities,P (FailurelSL),P (FailurelML),andP (FailurelLL),usedinequation(Eq1).InSection3.5,wecomparethejointdistributionsobtainedusingthehybridapproach

?andthosederivedfromtheRI-ISIanalysisFlemingetal.(2011).3.4FrequenciesofSmall,Medium,andLargeBreaksInTable1wepresentthefrequenciesusedinequation(Eq1)basedonNUREG-1829andRI-ISI.ThetablesNUREG-1829Meanrowreportscurrent-dayval-uesfromTable7.19ofTregoningetal.(2008),usinglinearinterpolationtoobtain exceedancefrequenciesfor2-inchand6-inchbreaks,andformingdto "ndwithin-categoryfrequenciesfor0.5-2.0-inchbreaks(Small)and2.0-6.0-inch breaks(Medium).TheLargevalueisbasedonthe6.0-inchexceedancefre-quency.RowRI-ISIPointEstimatecontainsanalogousvaluesbasedonthe pointestimatesreportedinFlemingetal.(2011)sTables5.1-5.4.The"nalrow ofthetableshowstheratiosofthesefrequenciesusingRI-ISIasthedenomina-tor.ThisrowindicatesthattheNUREG-1829meanfrequenciesusedinSTPs submittalarelargerthanthoseofRI-ISIbyfactorsof4.43,15.18,and2.27for small,medium,andlargebreaks.Table1:Frequencies(eventsperyear)forsmall,medium,andlargebreaksforNUREG-1829andRI-ISI.Here,Small,Medium,andLargecorrespondtobreaksinthe 0.5-2.0-inchcategory,2.0-6.0-inchcategoryand6.0-inch-or-greatercategory.Method/BreakSizeSmallMediumLargeNUREG-1829Mean1.59E-033.05E-045.20E-06RI-ISIPointEstimate3.59E-042.01E-052.29E-06Ratio(NUREG/RI-ISI)4.4315.182.273.5ProbabilityDistributionsGoverningBreakSizeandWeld CaseInTables2,3,and4weshowtheprobabilitydistributionsgoverningbreaksizeandweldcaseobtainedusingthehybridapproachforSTPssubmittaland theRI-ISIanalysis.Thetablesreportprobabilitydistributionsgoverningbreak sizeandweldcase,conditionalontheoccurrenceofaLOCA.Table2shows theprobabilityofabreakfallingintheNUREG-1829categories1-6forboth methods.Here,theHybrid-JohnsonMeansrowisbasedonthemeansofthe Johnsondistributions"ttothepercentileselicitedinNUREG-1829TregoningTuesday1 stMarch,2016:19:32,Page332of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6etal.(2008).TheRI-ISI-PointEstimaterowisbasedonthepointestimatesreportedintheRI-ISIanalysisFlemingetal.(2011).Thetables"nalrowshows theratiooftheprobabilitiesforeachofthesixcategories,usingthehybrid methodasthedenominator.ThetableshowsthattheRI-ISIanalysishassimilar probabilitymassasNUREG-1829incategory1andasmallerprobabilitymassin category2.Thisdecreaseincategory2,coupledwiththesmallerfrequencyata 0.5-inchbreak(normalizationbythisfrequencyyieldsexceedanceprobabilities) leadstoincreasedprobabilitymass,underRI-ISI,beingdistributedtocategories 3-6byfactorsof2.70,5.03,20.38,and15.68.Table2:ConditionalLOCAprobabilitiesbycategoryusingboththehybridmethodwiththeJohnsonmeansandRI-ISIpointestimates.Theratiosoftheprobabilities (latterdividedbyformer)forthetwomethodsareshowninthebottomrow.Method/CategoryCat1Cat2Cat3Cat4Cat5Cat6Hybrid-JohnsonMeans8.02E-011.91E-016.85E-036.82E-045.12E-057.72E-06RI-ISI-PointEstimate9.08E-016.84E-021.85E-023.43E-031.04E-031.21E-04Ratio(RI-ISI/Hybrid)1.130.362.705.0320.3815.68Table3showsthejointprobabilitydistributionacross45weldcases,basedoncurrent-dayestimatesforthehybridapproachusingthemeansofthe"tted Johnsondistributions.ThebottomrowofTable3correspondstothetoprowof Table2.Theright-mostcolumnofTable3showstheconditionalprobabilityofa breakoccurringineachweldcase,giventhatabreakoccurred.Table4presents thesameinformationwhenusingtheRI-ISILOCAfrequencypointestimates.Tuesday1 stMarch,2016:19:32,Page333of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6Table3:JointLOCAprobabilitiesforbreaksizeandweldcaseusingthemeansofthe"ttedJohnsondistributionsforcurrent-dayestimates.WeldCaseCat1Cat2Cat3Cat4Cat5Cat6 P(Break)Weld1-1A2.92E-031.18E-031.18E-041.83E-052.73E-061.13E-06 4.24E-03Weld2-1B3.90E-051.58E-051.57E-062.45E-073.65E-081.51E-08 5.66E-05Weld3-1C2.27E-059.20E-069.15E-071.42E-072.12E-088.81E-09 3.30E-05Weld4-21.43E-025.84E-035.87E-049.60E-051.28E-055.72E-06 2.09E-02Weld5-3A1.11E-035.10E-043.79E-055.07E-067.34E-073.87E-07 1.66E-03Weld6-3B1.11E-035.10E-043.79E-055.07E-067.34E-073.87E-07 1.66E-03Weld7-3C6.12E-052.82E-052.10E-062.81E-074.06E-082.14E-08 9.19E-05Weld8-3D1.22E-045.65E-054.20E-065.62E-078.13E-084.29E-08 1.84E-04Weld9-4A1.54E-021.10E-021.09E-031.76E-041.52E-05X 2.77E-02Weld10-4B8.24E-045.86E-045.83E-059.37E-068.13E-07X 1.48E-03Weld11-4C3.84E-042.73E-042.72E-054.37E-063.79E-07X 6.89E-04Weld12-4D7.06E-045.02E-047.03E-05XXX 1.28E-03Weld13-5A2.34E-031.74E-036.65E-055.95E-06XX 4.15E-03Weld14-5B1.13E-038.39E-043.75E-05XXX 2.01E-03Weld15-5C1.60E-031.19E-035.31E-05XXX 2.84E-03Weld16-5D1.21E-048.97E-054.01E-06XXX 2.15E-04Weld17-5E8.77E-046.50E-042.49E-052.23E-06XX 1.55E-03Weld18-5F0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld19-5G1.23E-049.09E-053.48E-063.11E-07XX 2.17E-04Weld20-5H6.05E-054.48E-052.00E-06XXX 1.07E-04Weld21-5I1.62E-041.60E-04XXXX 3.22E-04Weld22-5J0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld23-6A3.52E-023.20E-02XXXX 6.72E-02Weld24-6B5.47E-01XXXXX 5.47E-01Weld25-7A1.03E-017.76E-022.68E-031.91E-041.64E-05X 1.83E-01Weld26-7B4.40E-023.33E-021.15E-031.10E-04XX 7.85E-02Weld27-7C1.64E-021.24E-024.27E-044.10E-05XX 2.92E-02Weld28-7D1.87E-031.41E-034.88E-053.48E-063.00E-07X 3.34E-03Weld29-7E1.15E-038.65E-042.99E-052.13E-061.83E-07X 2.04E-03Weld30-7F6.03E-044.55E-041.57E-051.12E-069.65E-08X 1.08E-03Weld31-7G8.44E-046.38E-042.20E-052.11E-06XX 1.51E-03Weld32-7H4.62E-043.49E-041.21E-051.16E-06XX 8.24E-04Weld33-7I1.00E-047.59E-053.09E-06XXX 1.79E-04Weld34-7J1.81E-041.37E-045.56E-06XXX 3.23E-04Weld35-7K2.01E-041.98E-04XXXX 3.99E-04Weld36-7L0.00E+000.00E+00XXXX 0.00E+00Weld37-7M0.00E+000.00E+000.00E+000.00E+000.00E+00X 0.00E+00Weld38-7N3.20E-032.41E-038.37E-055.98E-065.15E-07X 5.70E-03Weld39-7O1.65E-041.25E-044.33E-063.10E-072.66E-08X 2.95E-04Weld40-8A7.55E-045.65E-042.35E-05XXX 1.34E-03Weld41-8B1.44E-031.07E-034.46E-05XXX 2.55E-03Weld42-8C1.55E-031.16E-034.83E-05XXX 2.76E-03Weld43-8D1.98E-041.48E-046.17E-06XXX 3.53E-04Weld44-8E5.63E-044.21E-041.75E-05XXX 1.00E-03Weld45-8F3.30E-052.47E-051.03E-06XXX 5.88E-05 P(Break)8.02E-011.91E-016.85E-036.82E-045.12E-057.72E-06 1.00E+00EstimatesofpiperupturefrequenciesinformtwokeyaspectsoftheanalysisinSTPsGSI-191submittal.Thesetwoaspectsareapparentinequation(Eq1),

whichinvolvesmeanfrequenciesofsmall,medium,andlargebreaksandcon-Tuesday1 stMarch,2016:19:32,Page334of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6Table4:JointLOCAprobabilitiesforbreaksizeandweldcaseusingpointestimatesfromRI-ISIFlemingetal.(2011).WeldCaseCat1Cat2Cat3Cat4Cat5Cat6 P(Break)Weld1-1A3.31E-034.25E-043.18E-049.23E-055.57E-051.78E-05 4.22E-03Weld2-1B4.42E-055.67E-064.24E-061.23E-067.44E-072.37E-07 5.63E-05Weld3-1C2.57E-053.30E-062.47E-067.17E-074.33E-071.38E-07 3.28E-05Weld4-21.62E-022.10E-031.58E-034.83E-042.61E-048.97E-05 2.07E-02Weld5-3A1.25E-031.83E-041.02E-042.55E-051.50E-056.07E-06 1.58E-03Weld6-3B1.25E-031.83E-041.02E-042.55E-051.50E-056.07E-06 1.58E-03Weld7-3C6.94E-051.01E-055.66E-061.41E-068.28E-073.36E-07 8.77E-05Weld8-3D1.39E-042.03E-051.13E-052.83E-061.66E-066.73E-07 1.75E-04Weld9-4A1.75E-023.94E-032.95E-038.84E-043.10E-04X 2.56E-02Weld10-4B9.34E-042.10E-041.57E-044.72E-051.66E-05X 1.37E-03Weld11-4C4.35E-049.81E-057.33E-052.20E-057.72E-06X 6.36E-04Weld12-4D8.00E-041.80E-041.89E-04XXX 1.17E-03Weld13-5A2.65E-036.24E-041.79E-043.00E-05XX 3.49E-03Weld14-5B1.28E-033.01E-041.01E-04XXX 1.68E-03Weld15-5C1.82E-034.27E-041.43E-04XXX 2.39E-03Weld16-5D1.37E-043.22E-051.08E-05XXX 1.80E-04Weld17-5E9.94E-042.33E-046.71E-051.12E-05XX 1.31E-03Weld18-5F0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld19-5G1.39E-043.26E-059.38E-061.57E-06XX 1.82E-04Weld20-5H6.85E-051.61E-055.40E-06XXX 9.00E-05Weld21-5I1.83E-045.75E-05XXXX 2.41E-04Weld22-5J0.00E+000.00E+000.00E+000.00E+00XX 0.00E+00Weld23-6A3.99E-021.15E-02XXXX 5.14E-02Weld24-6B6.20E-01XXXXX 6.20E-01Weld25-7A1.16E-012.79E-027.23E-039.60E-043.35E-04X 1.53E-01Weld26-7B4.99E-021.19E-023.10E-035.55E-04XX 6.55E-02Weld27-7C1.85E-024.44E-031.15E-032.07E-04XX 2.43E-02Weld28-7D2.12E-035.08E-041.32E-041.75E-056.11E-06X 2.78E-03Weld29-7E1.30E-033.11E-048.06E-051.07E-053.74E-06X 1.70E-03Weld30-7F6.83E-041.64E-044.24E-055.64E-061.97E-06X 8.96E-04Weld31-7G9.56E-042.29E-045.94E-051.06E-05XX 1.26E-03Weld32-7H5.24E-041.25E-043.25E-055.83E-06XX 6.87E-04Weld33-7I1.14E-042.73E-058.34E-06XXX 1.49E-04Weld34-7J2.05E-044.91E-051.50E-05XXX 2.69E-04Weld35-7K2.28E-047.12E-05XXXX 2.99E-04Weld36-7L0.00E+000.00E+00XXXX 0.00E+00Weld37-7M0.00E+000.00E+000.00E+000.00E+000.00E+00X 0.00E+00Weld38-7N3.62E-038.66E-042.26E-043.01E-051.05E-05X 4.75E-03Weld39-7O1.87E-044.48E-051.17E-051.56E-065.43E-07X 2.46E-04Weld40-8A8.56E-042.03E-046.34E-05XXX 1.12E-03Weld41-8B1.63E-033.85E-041.20E-04XXX 2.13E-03Weld42-8C1.76E-034.17E-041.30E-04XXX 2.31E-03Weld43-8D2.25E-045.32E-051.66E-05XXX 2.94E-04Weld44-8E6.38E-041.51E-044.72E-05XXX 8.37E-04Weld45-8F3.74E-058.87E-062.77E-06XXX 4.91E-05 P(Break)9.08E-016.84E-021.85E-023.43E-031.04E-031.21E-04 1.00E+00ditionalfailureprobabilities.TheformerarepreciselythefrequenciesthatwediscussinSection3.4,andestimatesofthelatterprobabilitiesareformedus-Tuesday1 stMarch,2016:19:32,Page335of393 DRAFTPART3.RESPONSETOEPNBCONSISTENCYOFWELDFREQUENCIESWITHRI-ISIPROGRAM:RAI6ingCASAGrande,basedonthejointprobabilitydistributionsthatwediscussinSection3.5.Inbothcases,wepreservecharacteristicsofNUREG-1829,an expertelicitationconcerningpiperupturefrequencies.ThemeanfrequenciesreportedinNUREG-1829Tregoningetal.(2008)arepreservedinthemeanfrequenciesdenoted f SL , f ML,and f LLinequation(Eq1).InSection3.4,weindicatethatifweretoinsteaduseRI-ISI,thesethreefre-quencieswoulddecreasebyfactorsof4.43,15.18,and2.27forsmall,medium, andlargebreaks.The5th,50th,and95thpercentilesofNUREG-1829frequenciesarepre-servedintheJohnsondistributionsusedinourhybridapproach

?,andwefurtherusetherelativefrequenciesinRI-ISIFlemingetal.(2011)toallocate failureswithinabreak-sizecategoryacrossweldcases.Ifweinsteaduseonly RI-ISIfrequenciestoconstructthedistributionoverbreaksizeandweldcase, theprobabilitymassincreasesbyfactorsof5.03,20.38,and15.68inthere-spectivecategories4,5,and6.Thisresultoccursforthreeprimaryreasons:

(i)theexceedancefrequencyatthesmallestbreaksize(0.5inch)issmallerin RI-ISIFlemingetal.(2011)thanNUREG-1829byafactorofnearly"ve(com-pare0.5-inchexceedancefrequenciesinTable5-6inFlemingetal.(2011)and Table7.19inTregoningetal.(2008));(ii)category2inRI-ISIhasasmaller probabilitymassthanthatfromNUREG-1829byafactorof0.36(seeTable2in Section3.5);and,(iii)thedegradation-basedfrequenciesinRI-ISIFlemingetal.

(2011)dropmoreslowlythanthepipe-rupturefrequenciesinNUREG-1829, particularlyincategories4-6.Wenotethatobservation(iii)isconsistentwiththe"attertrendsatlargerpipesizesreportedinthedegradationfrequency"analysisofHochreiter(2005).

Thatsaid,theapproachinSTPssubmittalinsteadmatchesthetrendsin NUREG-1829atlargerpipesizes,consistentwithcommentsinUhle(2005).Tuesday1 stMarch,2016:19:32,Page336of393 DRAFTPart4RAIResponses(Round2)4.1ML15091A440,APLABResponses4.1.1Question1:ProjectQualityAssuranceSTPResponse:(Item1,Page83)TheLARriskassessmentisbasedontheSTPNOCprocedureOPGP05-ZE-0001PRAAnalyses/AssessmentsundertheSTPOperationsQualityAssur-anceProgram(OQAP).TheprocedurestepswerecompletedbyABSConsulting personnelandSTPNOCPRAQuali"edAnalysts.ABSConsultingpersonnelare quali"edtotheSTPNOCprocedure.Allsupportinganalysesandcalculations wereperformedwithintheGSI-191QAprocessassummarizedintheLAREn-closure4-1,pagexx,Figure4,IllustrationofthemajorelementsoftheSTP qualityassuranceplanforrisk-informedclosureofGSI-191.Inaddition,theanalyses,calculation,andmethodologiesusedwerereviewedbyanindependentoversightgroup,UniversityofIllinoisatUrbana-Champaign.STPsstationcorrectiveactionprogramensuresthatappropriateattentionandcorrectiveactionsaretakenifassumptions,analyses,orinformationusedin previousdecisionmakingarechanged(e.g.,licenseevoluntaryaction)ordeter-minedtobeinerror.4.1.2Question2:ProjectQualityAssuranceSTPResponse:(Item2,Page83)AlionScienceandTechnology(Alion)isperformingtheSoftwareValidationandVeri"cationundertheauspicesofAlionsQualityAssuranceManualand QualityAssuranceProceduresreferredtoasAlionsQAProgram.TheQAPro-gramcomplieswith10CFR50AppendixBandNQA-1requirementsandhas beenauditedandapprovedbynumerousutilities,NUPICandNIAC.STPNOChasprovidedAlionwithOPGP07-ZA-0014,Revision9,SoftwareQualityAssuranceProgram.TherequirementsofOPGP07-ZA-0014andAlions complianceareprovidedinTable1.PerOPGP07-ZA-0014,CASAGrandeis classi"edasLevel3Software.TherequirementsforLevel3areprovidedbelow inTable10.1,excerptfromOPGP07-ZA-0014,Revision9.AtpresenttimeAlionhasmodi"edCASAGrandeandVersion1.7willbetheVeri"edandValidatedversionAlionwillissuetoSTPinadditiontothe aforementionedrequireddocuments.TheanticipateddateofissueisApril2, 2015.337 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:0PGP07-ZA-0014requirement,AlionscomplianceSTPALIONRequirementsSoftwareRequirementsSpeci"cationDesignSoftwareDesignSpeci"cation/TheoryManual UsersManualUsersManual TestProtocolSoftwareAdequacy/ValidationPlan TestPlanValidationPlan InstallationInstructions(UM)InstallationInstructions/UsersManualTable2:Table10.1excerptfrom0PGP07-ZA-0014,Revision9)Level1Level2Level3Level4Level5RequirementDocumentXXXXDesignDocumentXXX TestPlanDocumentXXX TestCaseDocument XXXXTestReportNote 1 Note 1 Note 1 Note 1UserInstruction/ManualNote 2 Note 2 Note 2 Note 2RetirementPlanDocumentNote 3 Note 3 Note 3 Note 3 1Requiredifthereare5ormoreTestCases 2SponsordeterminestheneedforaUserInstruction/Manual 3Requiredonlywhenthesoftwareordataisremovedfromaccessbyusers4.1.3Question3:ProjectQualityAssuranceSTPResponse:(Item3,Page84)ThePRAanalysisisnotrequiredtomeetAppendixBrequirements.ThePRAanalysisisundertheSTPOQAP.Vendorswerecontractedtoworkto acommonengineeringstandardthatrequiredapreparer,reviewer,andap-proval.Independentoversightwasalsopartoftheprocess.Asshowninthe"ow chartinEnclosure4-1,pagexx,vendor-supplieddocumentsandcalculationsare processedthroughSTPNOCEngineeringProcedure0PGP04-ZA-0328.RoverD utilizesdeterministicanalysespreviouslyperformedinsupportoftheDecember 2008submittalinresponsetoGL2004-02.Thesewereperformedinaccordance withAppendixBrequirements.Theserequirementswereinvokedbythecon-tractsSTPNOChadwithWestinghouseandwithPerformanceContractingInc.

(PCI).Thesub-contractorsincludedAlion;Enercon;Areva;andAutomated Engineeringservices(AES).Workbythesesub-contractorswasalsotoApp.B requirements.Inaddition,thesumpdesignandconstructionwasperformedinaccordancewithApp.Brequirements.4.1.4Question4:ProjectQualityAssuranceSTPResponse:(Item4,Page84)Asshowninthe"owchartinEnclosure4-1,pagexx,vendordocumentsareTuesday1 stMarch,2016:19:32,Page338of393 DRAFTPART4.RAIRESPONSES(ROUND2)processedthroughSTPNOCEngineeringProcedure0PGP04-ZA-0328.Introduction TheSTPrisk-informedGSI-191pilotprojectqualityassuranceprocessisillustratedinFigure1below.Asshowninthe"gure,projectcontractorsdevel-opinginputstothePRAarerequiredtohavealocalqualityassuranceprogram.

Ingeneral,thequalityassuranceprocessesthevendorsadoptedareuniqueto theprojectbutneverthelessincorporatestandardandgenerallyacceptedqual-ityassurancepractices.Eachvendorsprogramisdescribedinmoredetailin followingsections.Thevendorpersonnelassignedtotheprojectandresponsibleforproductqualityatthevendorlocationarequali"edtodoworkonthespeci"c(risk-informedpilot)projectpertheSTPNOCplantprocedure0PGP03-ZT-0138.In addition,theprojectusesindependenttechnicaloversightreviewforcriticalpeer reviewontheworkperformed.Aquali"edSTPNOCPRAanalystisultimatelyresponsibleforensuringthePRAinputsarereasonableforuseinthePRA.Personnelquali"edtothe STPanalysis/assessmentproceduretoperformPRAcalculationspertheSTP engineeringquali"cationprogramusethePRAinputs.Theoverallprogrammatic requirementsforPRAprojectsarecapturedin0PGP04-ZA-0604,Probabilistic RiskAssessmentProgram.Tuesday1 stMarch,2016:19:32,Page339of393 DRAFTPART4.RAIRESPONSES(ROUND2)FIGURE1Tuesday1 stMarch,2016:19:32,Page340of393 DRAFTPART4.RAIRESPONSES(ROUND2)ABSConsulting[ProbabilisticRiskAssessment]QualityProgramAspects:ABSconsultingpersonnelworkingontheprojectarequali"edtoperformtheSTPNOCplantprocedure0PGP05-ZE-0001,PRAAnalyses/Assessments.

0PGP05-ZE-0001isusedforallSTPPRAassessments,calculations,andappli-cationswhendataarebeingdevelopedoranalysesarerequired.Eachanalysisperformedin0PGP05-ZE-0001isassignedauniqueIDandrevisionnumber.TheIDfortherisk-informedGSI-191pilotlicensesubmittalis PRA-13-001,Revision0.Analysesandassessmentsmayberevisedasnecessary tore"ectnewinformationorchangedrequirements.TexasA&M[Thermal-Hydraulics]

QualityProgramAspects:Thethermal-hydraulicsmodelsarenewworkforSTP.Thatis,therisk-informedpilotprojectdidnotadoptexistingmodelsofcontainment,RCS,and ECCSduetolimitationsinthemodelingsoftware,nodalization,andapplication modellimitations.TheTAMUqualityplanfollowsstandardengineeringpracticerequiringonequali"edindividualtodevelopananalysisandasecond,independentreviewerto validatethework.Inaddition,thermal-hydraulicspracticeincludesveri"cation oftheinputsforthesimulationbycomparisonagainst(expected)steady-state (time-invariantboundaryconditions)andtransients.Becausethesimulationis foranoperatingplant,thesteady-stateoperatingpointisobtainedfromplant measurements.Inaddition,unmeasuredstatepointsarecon"rmedagainstother engineeringanalysesanddesignvalues.Existingsimulations(MAAP,RETRAN, licensingapplications)areusedforfurthersupport.Thetransientveri"cationfollowssteady-stateveri"cationandsince,ingen-eral,nodataexistformanyofthetransientssimulated,thesimulationisveri"ed againstotheracceptedtransientanalysessuchastheplantsimulator,UFSAR Chapter15analyses,andgenericanalysesintheopenliterature.Theresults ofthethermal-hydraulicmodelveri"cationsarecapturedindocumentsspeci"c totheveri"cation.Foreachspeci"ctransientcasecalculatedforuseintheengineeringanal-yses,thegenerallyacceptedengineeringpracticeofpreparerandreviewerwas followed.Eachindividualtransientanalysisisdocumentedinareportthatis identi"edwiththepreparerandreviewer.Thescopeofreviewincludesnotonly appropriateinputdatabutreasonablenessoftheresultsaswell.Anyresults thatappearedinconsistentwithintuitionwerestudiedandexplained.AlionScienceandTechnology[EngineeringAnalysis&Quanti"cation(CASA Grande)]QualityProgramAspects:AtthetimeFigure1wasdevelopedresponsibilityforengineeringanalysisandquanti"cationwaswithLANL.Subsequently,theseresponsibilitieswere transferredtoAlionScience.Therisk-informedpilotprojectscopeofworkwas deemednon-safetyandthereforenotperformedunderAlions10CFR50Ap-pendixB,10CFRPart21andASMENQA-1-1994QualityAssuranceProgram;Tuesday1 stMarch,2016:19:32,Page341of393 DRAFTPART4.RAIRESPONSES(ROUND2)however,forAlionsdevelopmentandreviewofcalculationsforthenon-safetyproject,bestengineeringpracticeswerefollowed.Theinitialstageofthenon-safetyprojectregardingCASAGrandewastodevelopthecalculationaltool, verifytheaccuracyofthetool,beginsoftwaredevelopmenttodevelopthecode, runatestcaseandperformacomparison.Testcaseswithcon"rmationusing handcalculationswereusedtoverifythattheCASAGrandecalculationalmeth-odswereaccurateandproper.ThecurrentSQAisdescribedintheresponseto RAI2above.UTAustin[UncertaintyQuanti"cation]

QualityProgramAspects:UTusesstandardqualitycontrolaspectsforanalyses,documents,andtech-nicalreports.Thisconsistsprimarilyofapreparer,areviewer,andanapprover (eitherinternaltoUTorexternal).UniversityofNewMexico[Chemical QualityProgramAspects:AllchemicalexperimentsworkisperformedusingtheUNMqualityassuranceprogrammanual,"Corrosion/HeadLossExperiments(CHLE)Project QualityAssuranceProgramManualRevision2",June18,2012.Standardlabo-ratorypracticewasfollowedforkeepinglaboratorynotesandobservations.UNMhasbeenperformingtheCorrosionHeadLossExperimental(CHLE)Programunderthequalityassuranceprogramthatwasdevelopedforthisproject.

Aspartofthisprogram,allcalculationsforconductingatestareperformedby onepersonandcheckedbyadtindividual.Metalionconcentrationshave beenanalyzedbyacommerciallabandinstrumentssuchaspHmetersandbal-anceshavebeencalibratedwithappropriatestandards.Writtenprocedureswere preparedandfollowedforeachtanktest.Aftereachexperimentwasconducted, areportwaswritten.ThatreportwascheckedbyaseparateindividualatUNM andwasthencheckedbyanindividualatSTPandanotherindividualatSo-teria/UIUCConsultants.Basedontheprocedurewehavefollowedforreport writingandchecking,wearenotawareofanyinaccuraciesbetweenthetests thatwereactuallydoneandtheresultsthatarereportedinthecorresponding reports.UniversityofIllinoisatUrbana-Champaign[TechnicalOversight]

AteamfromtheUniversityofIllinoisatUrbana-Champaign(UIUC)hasbeenprovidingIndependentTechnicalOversightoftheSTPNOCRisk-Informed GSI-191project.TwokeymembersofthisteamwerewithSoteriaCon-sultants(Soteria)in2012;therefore,theOversightfunctionwascarriedoutun-derSoteriathatyear.InJanuary2013,thetwokeymembersjoinedthefaculty oftheNuclearEngineeringDepartmentatUIUCand,fromthattime,theInde-pendentOversightoftheSTPprojectwasperformedunderacontractbetween STPNOCandUIUC.STPNOCcommissionedtheIndependentOversightteamtohelpensurethequalityandvalidityoftheresearchanddevelopmentundertaken.Themainob-jectiveofIndependentTechnicalOversighthasbeentoperformanindependent andin-depthscienti"creviewofthephenomenologicalmodelsandexperimentsTuesday1 stMarch,2016:19:32,Page342of393 DRAFTPART4.RAIRESPONSES(ROUND2)developedandconductedfortheRisk-InformedGSI-191project.TheOver-sightteamsscopeofworkcoveredthecriticalreviewofallthedocuments relatedtothetechnicalareasoftheprojectsuchaslocation-speci"cLoss-of-Coolant-Accident(LOCA)frequencymodeling,Jetformationphysics,Debris generation,Debristransport,Strainerconventionalheadloss,Penetration,Re-actorthermo-hydraulic,Boronprecipitation,Uncertaintyquanti"cation,Chem-icalCoating,andProbabilisticRiskAnalysis.ThescopeoftheOversight didnotincludethereviewoftheCASAGrandesoftwaredevelopment,run,or process.TheIndependentOversightTeamisspeci"callyquali"edtopeerreview themethodologies,experimentsandcalculationsoftheSTPproject.TheOver-sightteammembershaveacademic(holdingPh.D.s)andindustryexperiencein bothprobabilisticanddeterministicdomains,andarecapableof(1)understand-ingprobabilisticmethods(e.g.,PRAanduncertaintyanalysis),(2)analyzing physicalandchemicalphenomena(e.g.,containmentcorrosiontests,strainer performancetests,andchemicaltests,thermo-hydraulicmodeling)(3) providingscienti"candpracticalfeedback,and(4)producingtechnically-sound andclearpeerreviewdocumentation.TheIndependentOversightteamprovidedtheanalysisteam(allotherven-dors)withwrittencommentsandallofthesecommentswereformallyresolved.

Thecommentsandresolutionsaredocumentedandavailable.Eachsetofcom-mentswasdevelopedbyoneortwooversightteammembersandreviewedby thethirdmemberoftheteambeforeitssubmittaltoSTPNOCandtherelated analysisvendor.Soteria/UIUCsapproachincludedbothactiveandpas-siveoversight.TwoPh.D.sofSoteria/UIUCinteractedandcollaboratedwith theanalysisteamstoprovidefeedbackandtoactiveoversightservices.Be-causeofthemultidisciplinaryandintegrativenatureoftheproject,members oftheoversightgroupwererequiredtoparticipateinmeetingsandthenfollow uponthediscussionsandissueswiththeothergroupmembersinvolvedinthe STPproject.Speci"careasofconcernandreviewwerealsodiscussedwithSo-teria/UIUCspassiveoversightmembers(bothseniorandjuniorexpertsinthe related"elds).TheSoteria/UIUCteamwasinvolvedinbothinformaland formaloversightactivitiesfortheSTPNOCRisk-Informedproject.Exam-plesofinformalactivitieswere(1)reviewingpre-meetingtechnicalreportsand documentsrelatedtoNRCpublicmeetingsandprovidingcomments,(2)provid-ingtechnicalsupportindevelopingACRSpresentations,and(3)participating inbrainstormingsessionsondiversetechnicaltopicalareaswiththerequired follow-upontheproposedideas.Someoftheformaloversightactivitiesincluded (1)participatinginweeklytechnicalteamteleconferencesandprovidingfeed-back,(2)participatinginmonthlytechnicalmeetingsandprovidingcomments, and(3)reviewingreportsanddocumentsanddevelopingwrittencommentsand follow-upresolutions.Inconclusion,theindependentoversighthasperformedconcurrentpeerre-viewsofdocuments,communicatedreviewcomments,hasfollowedupwithre-viewcommentresolutions,andhasanalyzedindustrylimitationsandregulatory concernstotempercomments.Thatis,theoversightteamhasprovidedreason-Tuesday1 stMarch,2016:19:32,Page343of393 DRAFTPART4.RAIRESPONSES(ROUND2)ablecommentsdirectedtowardsensuringacademicallydefensibleworkresults,butrecognizesthattheprojectwillgenerallyadoptexistingtechnologies(al-beitinnewways).BasedontheSoteria/UIUCteamsreview,theSTPNOC Risk-Informedprojectisanoutstandingblendofadvancedandconventional methodsthatnotonlycontributestowardstheclosureoftheGSI-191issues, butalsomakesasigni"cantcontributiontotheformalincorporationofun-derlyingphysicalfailuremechanismsofcertainpost-LOCAeventsintoProba-bilisticRiskAssessment(PRA).Soteria/UIUCoversightactivitiescon"dently concludedthattheSTPNOCRisk-Informedproject,havingawell-designedcom-binationofprobabilisticanddeterministicmethodologies,hasmadeimportant contributionstotheclosureofGSI-191issues.TheSoteria/UIUCteamiscon-

"dentinthescienti"cvalidityofmethodologies,experiments,andcalculations.

TheoversightteamcouldnotarriveatthesameconclusionregardingtheCASA GrandecodebecausethereviewoftheCASAGrandesoftwaredevelopment, run,andprocesswerenotincludedinthescopeoftheworkspeci"edforthe oversightteam.4.1.5Question1:TreatmentofUnanalyzedPlantConditionsSTPResponse:(Item1c,Page85)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.NUREG 1829pipebreakfrequenciesforthesmallestoftheunboundedbreaksisused directlyinatop-downapproachthatpreservestheexceedancefrequenciesto determineUseofRoverDdoesnotinvolvetheriskassessmentparame-tersthatarethesubjectsofthisRAI.4.1.6Question7:HumanReliabilityAnalysisSTPResponse:(Item1c,Page85)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7).RoverDdoesnotrelyonabetweenacleanplantandas designedplantanalysisinaclassicPRAsetting,nordoesitinvolveanHRA analysisasdescribedinthisRAI.Instead,RoverDrelegatesallscenariosthat resultin"nedebrismorethantestedamountstofailure.4.1.7Question1:KeyAssumptions/KeySourcesofUncertaintySTPResponse:(Item1g,Page86)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure andusesNUREG1829pipebreakfrequencyforthesmallestoftheunbounded breakstodetermineUseofRoverDdoesnotinvolveitemsa,b,andg,above.

Foritemsc,d,e,andf:Tuesday1 stMarch,2016:19:32,Page344of393 DRAFTPART4.RAIRESPONSES(ROUND2)c.Boronprecipitationwillbeaddressedinseparatesubmittal.d.PipebreakfrequenciesforthequantilesofthearithmeticandgeometricNUREG1829elicitationsareprovidedinAttachment7.e.RoverDusescore"beraccumulationbasedonmeasureddataand"owrateoftheECCSandcoreduringcoldlegbreakscenarios.Theeon core"beraccumulationofupperandlowerboundsofuncertaintyforpool concentrationand"ltrationareprovidedinAttachment7.f.TheuncertaintyofcontinuumbreakversusDEGBisshowninAttach-ment7.4.1.8Question1:ValidityofAssumptiononPumpCon"gurationsSTPResponse:(Item1,Page87)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.InRoverD, designbasispumpcon"gurationsareboundedbythedeterministictestdata.

STPNOCevaluatedtwoadditionalcases:threetrainoperationandsingletrain operation.Thethreetraincon"gurationisboundedbythedeterministictest.

However,thesingletrainoperationisnotboundedbythetest.Forthesingle traincase,theamountof"berisone-halfthetestedamount.UseofRoverDdoesnotinvolvequanti"cationoftheitemsintheRAIabove.4.1.9Question7:CASAGrandetoPRAInterfaceSTPResponse:(Item7,Page87)ForRoverD,thesmallestbreaksizethatisevaluatedforfailureis12.814inches(DEGBofthesurgeline).RoverDusesmeasuredtestdatainsteadof uncertaintyboundswhichmayresultinextremecasestobeevaluatedinCASA Grande.RoverDdoesnotrelyonaCASAGrandeevaluationforfailure.CASA Grandeexhaustivelysamplespotentialbreaklocationstodeterminethesmallest breaksizethatwillgeneratemore"brousdebristhanwasinthedeterministic

test.RoverDisdescribedinAttachment7.4.1.10Question1:FidelitybetweenRELAPSimulationsandCASA GrandeSTPResponse:(Item1,Page87)TheanalysisdiscussedinthisRAIwasoriginallyperformedinJuly2014,subsequenttothesubmittaloftheNovember2013LAR.Thequalityassurance fortheanalysisisconsistentwiththedescriptionoftheTAMUqualityprogram aspectsintheresponsetoRAI4intheprecedingProjectQualityAssurance RAIs.Theanalysisisincludedasanenclosuretothisattachment.AsdescribedinAttachment7,RoverDusesthermal-hydraulicanalysestoshowthatallsmallbreaksandallhotlegbreaksaresuccessbasedonPCT.

RoverDdoesnotrelyon"delitywithCASAGrandeforsuccesscriteria.Tuesday1 stMarch,2016:19:32,Page345of393 DRAFTPART4.RAIRESPONSES(ROUND2)UseofRoverDappliesthedeterministictestingtoevaluatebypassandblock-age.4.1.11Question1:State-of-KnowledgeCorrelationSTPResponse:(Item1,Page88)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandecoupledtothePRAtogeneratecon-ditionalfailureprobabilities.RoverDisalesscomplexapproachthatrelegates breaksizesthatgenerateandtransportdebristhatisnotboundedbydeterminis-tictestingtofailureandusesNUREG1829pipebreakfrequencyforthesmallest oftheunboundedbreakstodetermineTheapplicationofRoverDelim-inatestheneedtoaccountforstate-of-knowledgeforLOCAfrequenciessince STPisonlyapplyingLOCAfrequencyasdeterminedfromNUREG1829.4.1.12Question1:SelectionofJohnsonParametersSTPResponse:(Item1,Page88)RoverDevaluationofDeltaCDFandDeltaLERFfrequenciesarenotde-velopedfromsamplingaJohnsondistribution.Instead,theyaretakendirectlyfromtheNUREG1829tableforthegeometricmeanaggregation.InSection4.3 ofAttachment7,thequantilesforboththearithmeticandgeometricaggrega-tionareshownforallquantilesdevelopedfromtheNUREG1829elicitation.

TheSTPPRAModelofRecorddeterminationofplantaverageCDFandLERF isunchangedinRoverD.4.2ML15091A440,EMCBResponses4.2.1Question2STPResponse:(Item2,Page89)Toclarifythepreviousresponse:

• Case1correspondstothemaximumdebrisloadingatthemaximumtem-perature.*Case2correspondstothemaximumdebrisloadingattheminimumtem-perature.Therefore,theanalysisboundsallpossibledebrisloadingandtemperaturecombinations.4.3ML15091A440,ESGBResponses4.3.1Question23:ChemicalSTPResponse:(Item23,Page89)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemicalTuesday1 stMarch,2016:19:32,Page346of393 DRAFTPART4.RAIRESPONSES(ROUND2)Consequently,thesconclusioniscorrect,albeitforadtrea-son.4.3.2Question24:ChemicalSTPResponse:(Item24d,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.4.3.3Question25:ChemicalSTPResponse:(Item25d,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerateandtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL

• corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.4.3.4Question26:ChemicalSTPResponse:(Item26c,Page90)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

ChemicalareaccountedforinthedeterministictestingandtheL*corre-lationisnotused,noristhereaneedtoapplyafactortoaccountforchemical thus,plant-speci"ctestingaccountsforthechemicalheadloss.RoverD doesnotrelyonthetestdatafromSouthernNuclearCompany.4.3.5Question27:ChemicalSTPResponse:(Item27,Page91)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

Chemicalareaccountedforintheplant-speci"cdeterministictesting.4.3.6[ML15091A440]Question28:ChemicalSTPResponse:(Item28,Page91)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerateTuesday1 stMarch,2016:19:32,Page347of393 DRAFTPART4.RAIRESPONSES(ROUND2)andtransportdebristhatisnotboundedbydeterministictestingtofailure.Chemicalareaccountedforintheplant-speci"cdeterministictestingand STPnolongerintendstoapplyacorrelationtodeterminechemical4.3.7Question29:ChemicalSTPResponse:(Item29,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforchemicalChem-icalincludingzinc,areaccountedforintheplant-speci"cdeterministic

testing.4.3.8Question30:ChemicalSTPResponse:(Item30,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical areaccountedforintheplant-speci"cdeterministictesting.4.3.9Question31:ChemicalSTPResponse:(Item31,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical areaccountedforintheplant-speci"cdeterministictesting.AsdescribedinAttachment7,thetestingwasbasedonanassumptionoftwotrainsoperating.Inaddition,RoverDevaluatesthesingle-traincasewhere thedeterministicsuccesscriterionishalfofthetwotrainoperatingcasedebris.4.3.10Question32:ChemicalSTPResponse:(Item32,Page92)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.Chemical includingpresumedradiationareconsideredtobeaccountedfor intheconservatismofplant-speci"cdeterministictesting,whichisperformed perWCAP-16530.RAIresponsesintheNRCreviewedWCAP-16530-NP-Ain-dicatethatradiolysisandeofradioactivespecieswouldnotbeexpected tohaveasigni"cant4.3.11Question33:ChemicalSTPResponse:(Item33,Page93)Tuesday1 stMarch,2016:19:32,Page348of393 DRAFTPART4.RAIRESPONSES(ROUND2)HistoricalinformationisavailableconcerningCRUDreleasefrompre-outageCRUDcleanupperformance.CRUDreleasedataduringforcedoutages,includ-ingreactortrips,isboundedbyCRUDburstcleanupdataduringrefueling

outages.TheoutagereleasedatapertaintoreleasesfollowingattemptstoremoveCRUDfromsurfacesusingaggressivechemicalcleaningproductssuchashy-drogenperoxidetopurposelyremoveasmuchCRUDaspossiblefromtheplant priortooutagework(primarilyforALARAinterest).ThemeasurementofCRUDmassisbasedelementalanalysis,notactualweight.ThehistoryoftheweightofCRUDremoved(usingelementalanalysis) fromSTPduringoutageCRUDremovalsisshowninthe"gurebelow.The CRUDmeasurementsareconsistentwithindustrypracticeforthisperformance

indicator.The"gureshowstheamountofNiremoved,notallmetals.However,NiisthepredominantcontributortotheCRUDinventory.The"gureshowsthe totalamountofCRUDremovedduringthecrudburstevolutionandcleanup.

TheCRUDreleasedismostlysolubleorverysmallparticulate(<1micron)insize.ShownaswellistheactivityofCo58whichhelpsgiveanunderstanding ofhowmuchoftheCRUDiscomingfromthefuel.STPfurtherperformsfuel ultrasoniccleaningwhichisanevenmoreaggressivecleaningtechniquethan chemicalcleaning,removingsubstantialamountsofCRUDfromreloadfuel.

Thisinventoryreductionisnotshownonthegraph.Asthegraphbelowshows,recentCRUDamountsarelessthan2lbsuchthatCRUDisnotasigni"cantcontributortothedebrisinventory.4.3.12Question34:ChemicalSTPResponse:(Item34,Page93)Figure3showsweightedmeanquantitiesdeterminedforlargebreaksfromaCASAGrandeplantstateCase.TheCASAGrandequantitiesarebasedona 17DZOI.Table2showstestedstrainer"berquantitiesgeneratedfromaCAD modelmacrousinga7DZOIfromaspeci"clocation(HotLeg).Tuesday1 stMarch,2016:19:32,Page349of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.3.13Question8:CoatingsSTPResponse:(Item8,Page93)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverDdoes notrelyonacorrelationormodeltoaccountforcoatings.NotethatMarinite hasbeenremovedfromtheSTPcontainmentbuildingsandthetestincluded approximately183lbmofpowderedMariniteboardwhichisalmosttwicethe amountofepoxyintroducedaschips.TheMarinitecanreasonablybeconsidered tomakeupfortheunquali"edepoxy.4.3.14Question9:CoatingsSTPResponse:(Item9,Page93)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforcoatings.Coatingsareac-countedforintheplant-speci"cdeterministictesting.Thequantityofinorganic zincintheSTPplant-speci"ctestingwasbasedon5DZOI.4.3.15Question10:CoatingsSTPResponse:(Item10,Page94)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabili-ties.RoverDisalesscomplexapproachthatrelegatestofailurebreaksizesthat generateandtransportdebrisnotboundedbydeterministictesting.RoverD doesnotrelyonacorrelationormodeltoaccountforcoatings.Coatingsare accountedforintheplant-speci"cdeterministictestingwhichdoesnotrelyon failuretiming.4.4ML15091A440,SCVBResponses4.4.1Question10STPResponse:(Item10c,Page96)STPNOCwilladdareferencetotheUFSARsectionsreferencedabovetoprovideabriefsummaryofthedesignbasisandreferencetothedetailedde-scriptionthatwillbeprovidedinAppendix6AtotheUFSAR.Thebriefsummarywillbewordedsimilartothedescriptionbelow,usingtheappropriatefunction/GDCinthebrackets:TheLicensingBasisfor[containmentheatremoval]withregardtoofdebrisonemergencysumpstrainerstotheextentthatthestrainerssupportthe[CSSorECCS]elementofthe[containmentheatremovalfunction],isarisk-informedanalysisthatshowsthereisahighprobabilitythat[CSSorECCS]can performitsdesignbasisfunctionsbasedonplant-speci"cprototypicaltestingTuesday1 stMarch,2016:19:32,Page350of393 DRAFTPART4.RAIRESPONSES(ROUND2)usingdeterministicassumptionsthatprovidesafetymarginanddefense-in-depthandthattheriskfrombreaksthatcouldgeneratedebristhatisnotboundedby thetestingisverysmallinaccordancewiththecriteriaofRG1.174.Theconservatisminthetestingissigni"cantenoughthatusingrealisticanalysisandtesting,itisnotlikelythatdebrisonthestraineroron thecorewouldresultinfueldamage.Inaddition,theofdebrisdonot compromisecontainmentintegritywhichensuresdefenseindepthispreserved evenintheunlikelyeventthecoreiscompromised.TheSTPRiskoverDeterministic(RoverD)methodologywasusedtoevalu-atetheeofdebris.RoverDrelegatesbreaksizesthatgenerateandtransport debristhatisnotboundedbydeterministictestingtofailure(coredamage).It thenappliestheNUREG1829pipebreakfrequencyforthesmallestunbounded breakstodeterminetheincreaseincoredamagefrequency.Theincreaseiscom-paredtothecriteriainRG1.174.Theanalysisshowsthattheriskfromthe unboundedbreaksisverysmall,asde"nedbyRG1.174.Anexemptionto[GDC 38]hasbeenapprovedtoallowapplicationoftherisk-informedanalysisinstead ofthesinglefailureassumptionrequiredby[GDC38].Theexemptionapplies tothescopeofbreaksthatgenerateandtransportdebrisnotboundedbythe deterministictesting.DetailsofthedesignbasisfortheofdebrisonthefunctionoftheemergencysumpstrainersisprovidedinUFSARAppendix6A.STPNOCwillrevisetheUFSARChapter3evaluationsagainstCriteria35,38,and41(Plannedchangesareunderlined):3.1.2.4.6.1EvaluationAgainstCriterion35TheECCSisprovidedtocopewithanyLOCAintheplantdesignbasis.Abundantcoolingwaterisavailable inanemergencytotransferheatfromthecoreataratettomaintain thecoreinacoolablegeometryandtoassurethatcladmetal/waterreactionis limitedtolessthan1percent.Exceptfortheeofdebris,adequatedesign provisionsaremadetoassureperformanceoftherequiredsafetyfunctionseven withasinglefailure.TheSTPRiskoverDeterministic(RoverD)methodology wasusedtoevaluatetheeofdebris.RoverDrelegatesbreaksizesthat generateandtransportdebristhatisnotboundedbydeterministictestingto failure(coredamage).ItthenappliestheNUREG1829pipebreakfrequency forthesmallestunboundedbreakstodeterminetheincreaseincoredamage frequency.TheincreaseiscomparedtothecriteriainRG1.174.Theanalysis showsthattheriskfromtheunboundedbreaksisverysmall,asde"nedbyRG 1.174.AnexemptiontoGDC35hasbeenapprovedtoallowapplicationofthe risk-informedanalysisinsteadofthesinglefailureassumptionrequiredbyGDC 35.Theexemptionappliestothescopeofbreaksthatgenerateandtransport debrisnotboundedbythedeterministictesting.Detailsoftheconditionsfor theexemptionareincludedinAppendix6A.DetailsofthecapabilityofthesystemsareincludedinSection6.3.Aneval-uationoftheadequacyofthesystemfunctionsisincludedinChapter15.Per-formanceevaluationshavebeenconductedinaccordancewith10CFR50.46and 10CFR50AppendixK.Tuesday1 stMarch,2016:19:32,Page351of393 DRAFTPART4.RAIRESPONSES(ROUND2)3.1.2.4.9.1EvaluationAgainstCriterion38TheCHRSconsistsoftheCSS,theReactorContainmentFanCooler(RCFC)Subsystemandtheresidual heatremoval(RHR)heatexchangers.TheCHRSactsinconjunctionwiththe SafetyInjectionSystemtoremoveheatfromtheContainment.TheCHRSis designedtoaccomplishthefollowingfunctionsintheunlikelyeventofaLOCA:

torapidlycondensethesteamwithintheContainmentinordertopreventover pressurizationduringblowdownoftheRCS;andtoprovidelong-termcontinuous heatremovalfromtheContainment.Initially,theCSSandthehigh-andlow-headsafetyinjection(HHSIandLHSI)pumpstakesuctionfromtherefuelingwaterstoragetank(RWST).Dur-ingtherecirculationphase,theCSSandtheHHSIandLHSIpumpstakesuction fromtheContainmentemergencysumps.TheCHRSisdividedintothreetrains.

Eachtrainissizedtoremove50percentofthesystemdesignheatloadatthe startofrecirculation.EachtrainoftheCHRSissuppliedpowerfromaseparate independentClass1Ebus.Theredundancyandcapabilityoftheand EmergencyPowerSystemsarepresentedintheevaluationagainstCriterion17.

Redundantsystemtrainsandemergencydieselpowersuppliesprovideassurance thatsystemsafetyfunctionscanbeaccomplished.AnexemptiontoGDC38has beenapprovedtoallowapplicationofarisk-informedanalysisinsteadofthesin-glefailureassumptionrequiredbyGDC38,toaddresstheofdebris.The STPRiskoverDeterministic(RoverD)methodologywasusedtoevaluatethe ofdebris.RoverDrelegatesbreaksizesthatgenerateandtransportdebris thatisnotboundedbydeterministictestingtofailure(coredamage).Itthenap-pliestheNUREG1829pipebreakfrequencyforthesmallestunboundedbreaks todeterminetheincreaseincoredamagefrequency.Theincreaseiscomparedto thecriteriainRG1.174.Theanalysisshowsthattheriskfromtheunbounded breaksisverysmall,asde"nedbyRG1.174.Theexemptionappliestothescope ofbreaksthatgenerateandtransportdebrisnotboundedbythedeterministic testing.DetailsoftheconditionsfortheexemptionareincludedinAppendix

6A.Forfurtherdiscussion,seethefollowingsectionsoftheUFSAR:

ResidualHeatRemovalSystem5.4.7DesignforDebrisApp.6ACon-tainmentSystems6.2EngineeredSafetyFeaturesActuationSystem7.3Onsite PowerSystem8.3AccidentAnalysis15.03.1.2.4.12.1EvaluationAgainstCriterion41TheCSSisprovidedtore-ducetheconcentrationandquantityof"ssionproductsintheContainment atmospherefollowingaLOCA.Per10CFR50.44,hydrogenrecombinersareno longerrequiredfordesignbasisaccidents.TheequilibriumsumppHismaintainedbytrisodiumphosphate(TSP)con-tainedinbasketsonthecontainment"oor.TheinitialCSSwaterandspilledRCS waterdissolvestheTSPintothecontainmentsumpallowingrecirculationofthe alkaline"uid.Eachunitisequippedwiththree50-percentspraytrainstaking suctionfromtheContainmentsump.EachContainmentspraytrainissupplied powerfromaseparatebus.Eachbusisconnectedtoboththeandthe StandbyPowerSupplySystems.ThisassuresthatforOnsiteorforElec-Tuesday1 stMarch,2016:19:32,Page352of393 DRAFTPART4.RAIRESPONSES(ROUND2)tricalPowerSystemfailure,theirsafetyfunction(exceptfortheconsiderationofdebriscanbeaccomplished,assumingasinglefailure.Anexemption toGDC41hasbeenapprovedtoallowapplicationofarisk-informedanalysis insteadofthesinglefailureassumptionrequiredbyGDC41,toaddresstheef-fectsofdebrisontheCSSfunction.TheSTPRiskoverDeterministic(RoverD) methodologywasusedtoevaluatetheeofdebris.RoverDrelegatesbreak sizesthatgenerateandtransportdebristhatisnotboundedbydeterministic testingtofailure(coredamage).ItthenappliestheNUREG1829pipebreak frequencyfortheunboundedbreakstodeterminetheincreaseincoredamage frequency.TheincreaseiscomparedtothecriteriainRG1.174.Theanalysis showsthattheriskfromtheunboundedbreaksisverysmall,asde"nedbyRG 1.174.Theexemptionappliestothescopeofbreaksthatgenerateandtransport debrisnotboundedbythedeterministictesting.Detailsoftheconditionsfor theexemptionareincludedinAppendix6A.Post-accidentcombustiblegascontrolisassuredbytheuseoftheSupple-mentaryContainmentPurgeSubsystem.Forfurtherdiscussion,seethefollowingsectionsoftheUFSAR:ContainmentSystems6.2ContainmentSpraySystemIodineRemoval6.5.2 DesignforDebrisApp.6A ContainmentHydrogenSamplingSystem7.6.5 ContainmentHVACSystem9.4.54.4.2ML15246A128,Question11STPResponse:(Item11,Page96)PerSTPUFSARChapter3.1.2.4.9.1,GDC38ismetbyRCFCworkinginconjunctionwithCSSandECCS(LHSIthroughtheRHRheatexchangers)to removeheatfromthecontainment.Thescopeoftheexemptionwillapplyalso totheECCSbecauseofitsrelianceonthesumpstrainers.OnlytheCSSandthe ECCSfunctionsaredirectlybydebrissincetheyarethecontainment heatremovalfunctionsthatrelyonthesumpstrainersintherecirculationphase.

TheRCFCcoolingheatsinkisindependentNoexemptionisproposedtoapplytothesupportsystemsfortheCSSortheECCS.Theproposedexemptionsapplyonlyfortheofdebris.Noneofthe CSSorECCSsupportsystemsrelyontheECCSemergencysumpsandstrainers toperformtheirsupportfunctionandthuswillnotbebydebris.4.4.3ML15246A128,Question12(1)STPResponse:(Item(1),Page96)STPNOCproposesthattheexemptionwouldapplyforthisrequirementforthoseLOCAbreaksthatcouldgenerateanamountofdebristhatisnotbounded bythedeterministictesting.CurrentSTPdesignbasiscalculationsarebasedon RCFCfunctioninginconjunctionwithCSSandECCS,whichcanbe bydebris.Tuesday1 stMarch,2016:19:32,Page353of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.4ML15246A128,Question12(2)STPResponse:(Item(2),Page96)Usingcurrentdeterministicassumptions,STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupport theCSSandECCSfunctionfortheofdebrisproducedbyLOCAbreaks thatcangeneratedebristhatisnotboundedbyplant-speci"cdeterministic testing,asdescribedinRoverD.4.4.5ML15246A128,Question12(3)STPResponse:(Item(3),Page96)STPdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformanysupport functionforemergencypowerforCSSorECCSintheeventofaLOOP.4.4.6ML15246A128,Question12(4)STPResponse:(Item(4),Page96)TheSTPapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsinglefailure requiredbytheGDC.Inaccordancewiththesinglefailurecriteria,asingle occurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoallthree emergencysumpstrainers.STPNOCrequestsexemptiontothisrequirement forthedebrisfromLOCAbreaksthatcangeneratedebristhatisnot boundedbydeterministictestingtoallowtheapplicationofarisk-informed analysisthatshowsthattheriskfromdebrisisverylow,inaccordance withtheRG1.174criteria,asdescribedinRoverD.4.4.7ML15246A128,Question12(4)a.STPResponse:(Item12a,Page96)TheSTPNOCapplicationspeci"callyrequestsexemptiontoItem(4),whichhasadirectlinktoItems(1)and(2).NoexemptiontoItem(3),LOOP,is

needed.4.4.8ML15246A128,Question12(4)b.STPResponse:(Item12b,Page96)ThescopeoftheexemptionappliesforLOCAbreaksizesandlocationsthatpotentiallygeneratedebristhatexceedsthequantityboundedbySTP plant-speci"ctesting.Thatscopeisgenerallydescribedasbreakslargerthan approximately12.8"IDinlocationswhereastamountof"brousdebris canbegeneratedandtransportedtothesump.Forty-"ve(45)weldlocations havecurrentlybeenidenti"edonthepressurizersurgelineandRCSmainloop piping.Tominimizethepotentialthatalateranalysiscouldcausethespeci"c locationstochange,therequestedexemptionisbasedonthebreaksabilityto generatettransportabledebris,asdescribedinRoverD.Thebasisfortheexemptionisdescribedintheresponsetothe"rstRAIabove.Tuesday1 stMarch,2016:19:32,Page354of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.9ML15246A128,Question13STPResponse:(Item13,Page97)NoexemptionisproposedtoapplytothesupportsystemsfortheCSS.Theproposedexemptionsapplyonlyfortheeofdebris.NoneoftheCSS supportsystemsrelyontheECCSemergencysumpsandstrainerstoperform theirsupportfunctionandthuswillnotbebydebris.4.4.10ML15246A128,Question14(1)STPResponse:(Item(1),Page97)NoexemptionisproposedtoapplytothesupportsystemsfortheCSS.Theproposedexemptionsapplyonlyfortheeofdebris.NoneoftheCSS supportsystemsrelyontheECCSemergencysumpsandstrainerstoperform theirsupportfunctionandthuswillnotbebydebris.4.4.11ML15246A128,Question14(2)STPResponse:(Item(2),Page97)Usingdeterministicassumptions,STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupporttheCSS functionfortheofdebrisproducedbyLOCAbreaksthatcangenerate debristhatisnotboundedbyplant-speci"cdeterministictesting,asdescribed inRoverD.4.4.12ML15246A128,Question14(3)STPResponse:(Item(3),Page97)STPNOCdoesnotproposeexemptiontothisrequirementsincethesefunc-tionsarenotbydebris.4.4.13ML15246A128,Question14(4)STPResponse:(Item(4),Page97)STPNOCdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformany supportfunctionforemergencypowerforCSSintheeventofaLOOP.4.4.14ML15246A128,Question14(5)STPResponse:(Item(5),Page97)TheSTPNOCapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsingle failurerequiredbytheGDC.Inaccordancewiththesinglefailurecriteria,a singleoccurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoall threeemergencysumpstrainers.STPNOCrequestsexemptiontothisrequire-menttoallowtheapplicationofarisk-informedanalysisthatshowsthatthe riskfromdebrisisverylow,inaccordancewiththeRG1.174criteria.4.4.15ML15246A128,Question14(5)(a)STPResponse:(Item(a),Page97)Response:Seeresponseto(b)below.Tuesday1 stMarch,2016:19:32,Page355of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.4.16ML15246A128,Question14(5)(b)STPResponse:(Item(b),Page98)STPNOCrequestspartialexemption;i.e.,onlyItem2above.Asstatedabove,STPNOCsanalysisandtestingdoesnotassurethattheemergencysump strainerswillbeavailabletosupporttheCSSfunctionfortheofdebris producedbyLOCAsthatgenerateandtransportdebristhatisnotboundedby testing,asdescribedinRoverD.Forty-"ve(45)weldlocationshavecurrently beenidenti"edonthepressurizersurgelineandRCSmainlooppiping.Tomin-imizethepotentialthatalateranalysiscouldcausethespeci"clocationsto change,therequestedexemptionisbasedonthebreaksabilitytogenerate ttransportabledebris,asdescribedinRoverD.4.4.17ML15246A128,Question15STPResponse:(Item15,Page98)NoexemptionisneededforsystemsthatsupportECCS.Thedebrisonlysystemsthatrelyontheemergencysumpstrainersasasupportsystem.

NoneofthesupportsystemsrequiredforECCSoperabilitysuchascooling water,instrumentationandcontrol,andnormalandemergencypowerrelyonthe emergencysumpstrainerstoperformtheirfunction.Therequestedexemption forGDC35theECCSsupportsystems(AndtherequestedexemptionsforGDC 38and41donotapplytotheCSSsupportsystems.)4.4.18ML15246A128,Question16(1)STPResponse:(Item(1),Page98)TheSTPNOCproposedexemptionwouldapplyforthisfunctionalrequire-ment.AsdiscussedinpriorresponsesanddescribedintheRoverDmethodology, thefunctionoftheECCSemergencysumpisassumedtofailfordebristhatex-ceedstheamountinthedeterministictesting.Undertheseassumptions,failure ofthesumpandstrainerswillresultinlossofcoolingtothecore.4.4.19ML15246A128,Question16(2)STPResponse:(Item(2),Page98)STPNOCsanalysisandtestingdoesnotassurethattheemergencysumpstrainerswillbeavailabletosupporttheECCSfunctionfortheofdebris producedbyLOCAsthatgenerateandtransportdebristhatisnotboundedby testing,asdescribedinRoverD.Consequently,STPNOCisrequestingexemption forthatscopeofLOCAsthatwillproduceandtransporttdebristo exceedthedebrisformingthebasisforthedeterministictestingdescribedin RoverD.4.4.20ML15246A128,Question16(3)STPResponse:(Item(3),Page98)STPNOCdoesnotproposeexemptiontothisrequirementsincetheseECCSsupportfunctionsarenotbydebris.4.4.21ML15246A128,Question16(4)STPResponse:(Item(4),Page98)Tuesday1 stMarch,2016:19:32,Page356of393 DRAFTPART4.RAIRESPONSES(ROUND2)STPNOCdoesnotproposeanexemptiontothisrequirement.Debrisonlythefunctionoftheemergencysumpstrainerswhichdonotperformany supportfunctionforemergencypowerforECCSintheeventofaLOOP.4.4.22ML15246A128,Question16(5)STPResponse:(Item(5),Page98)TheSTPNOCapplicationrequestedexemptiontothisrequirementinordertoallowarisk-informedmethodologyinlieuofthedeterministicworstsingle failurerequiredbytheGDC.Inaccordancewiththesinglefailurecriteria,a singleoccurrencethatcausesmultiplefailuresisconsideredasinglefailure.The ofdebrisforthebreaksdescribedin(2)aboveareanalyzedtoall threeemergencysumpstrainers.STPNOCrequestsexemptiontothisrequire-mentforthedebrisfromLOCAbreaksthatcangeneratedebristhatis notboundedbydeterministictestingtoallowtheapplicationofarisk-informed analysisthatshowsthattheriskfromdebrisisverylow,inaccordance withtheRG1.174criteria,asdescribedinRoverD.4.4.23ML15246A128,Question16(5)(a)STPResponse:(Item(a),Page98)Seeresponseto(b).4.4.24ML15246A128,Question16(5)(b)STPResponse:(Item(b),Page99)STPNOCisrequestingapartialexemptionasdiscussedintheresponsesabove.TheproposedexemptiontoGDC35wouldapplytoItems(1),(2),and (5)forthescopeofbreaksdescribedin(2).Thetechnicalbasisisdescribedin theRoverDmethodology(Attachment7).4.4.25ML15246A128,Question17STPResponse:(Item17,Page99)STPwillrespondtothisRAIinaseparatesubmittal.4.4.26ML15246A128,Question18(a)(b)(c)(d)STPResponse:(Item(d),Page100)TheRoverDmethodologydoesnotuseRELAP5-3DorMELCORforcon-tainmentconditions.4.5ML15091A440,SNPBResponses4.5.1Question6STPResponse:(Item1,Page101)Fullblockageanalysesareperformedprimarilytoshowadequatecooling"owintheextremecasewhereallthenormal"owpathsareblockedbydebris.

Basedonmeasurementsof"ltrationoftheSTPstrainerdesign,there istdebrispenetratingthestrainerstoeelyblockthenormal"ow channels.IntheRoverDanalysisitisshownthatverylittle"berarrivesonthe coreincoldlegbreaks.Theamountsaresosmallthatitisunlikelymixing"owsTuesday1 stMarch,2016:19:32,Page357of393 DRAFTPART4.RAIRESPONSES(ROUND2)willbeimpeded.ThereforeSTPNOChasconcludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.2Question7STPResponse:(Item2,Page102)Fullblockageanalyseswithasmallunblockedchannelareperformedprimar-ilytoshowthemargintoadequatecooling"owintheextremecasewhereallthe normal"owpathsareblockedbydebris.Basedonmeasurementsof"ltration oftheSTPstrainerdesign,thereistdebrispenetratingthe strainerstoeelyblockthenormal"owchannels.IntheRoverDanalysisit isshownthatverylittle"berarrivesonthecoreincoldlegbreaks.Theamounts aresosmallthatitisunlikelymixing"owswillbeimpeded.ThereforeSTPNOC hasconcludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.3Question8STPResponse:(Item3,Page102)Basedonmeasurementsof"ltrationoftheSTPstrainerdesign,thereisitdebrispenetratingthestrainerstoeelyblockthenor-mal"owchannels.IntheRoverDanalysisitisshownthatverylittle"berarrives onthecoreincoldlegbreaks.Theamountsaresosmallthatitisunlikelymix-ing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.4.5.4Question9STPResponse:(Item4,Page102)TheRoverDanalysisreliesonthecurrentUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatverylittle"berarrivesonthecoreincoldlegbreaks.Theamountsareso smallthatitisunlikelymixing"owswillbeimpeded.ThereforeSTPNOChas concludedthatadequatecirculationwillbeavailabletodiluteboricacid.4.5.5Question10STPResponse:(Item5,Page103)TheRoverDanalysisreliesontheUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatvery little"berarrivesonthecore.Theamountsaresosmallthatitisunlikely mixing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.Insummary,STPNOCsevaluationshowsthatthesmallamountsof"berthatmayaccumulatewouldnotcorecoolingorBAP,suchthattheywould notclosingGL2004-02.STPNOCsanalysisissimilarinapproachand conclusionstohowtheNRCaddressedBAPintheSEtoWCAP16793-NP.4.6ML15091A440,SSIBResponses4.6.1Question43STPResponse:(Item43,Page103)Tuesday1 stMarch,2016:19:32,Page358of393 DRAFTPART4.RAIRESPONSES(ROUND2)AnapplicationwasmadetowithholdthisinformationfrompublicinspectionaspartofaletterdatedMay15,2014(ADAMSAccessionNo.ML14149A353) asitappearedinCASAGrandeinput"lesthatweresubmittedtotheNRCfor review.Permissiontowithholdthedocumentpursuantto10CFR2.390(b)(5) andSection103(b)oftheAtomicEnergyActof1954,asamended,wasgranted onML14092A557datedJune4,2014.Assuch,Reference46,wasandis,re-spectfullynotincludedinthesubmittal.ThemethodologyusedbySTPNOC(LAREncl.4-3Rev.2)forsizedistri-butionsofLDFG(%ofeachsizecategory)destroyedbyapostulatedZOI,has beenpreviouslyreviewedbytheNRCintheIndianPointEnergyCenterCor-rectiveActionsforGenericLetter2004-2document(i.).IntheIndianPoint EnergyCenterCorrectiveActionsdocument,NRCreviewersstatedThe foundthisapproachforNukon RandTemp-Mat TMtobeacceptablebecauseitisconsistentwithormoreprecisethantheDDTSevaluations,whendiscussing themethodologyusedforsizedistributionsofLDFGgeneratedwithintheZOI; thissamemethodologywasimplementedforSTP.i.ML082050433.IndianPointEnergyCenterCorrectiveActionsforGenericLetter2004-02,2008.4.6.2Question44STPResponse:(Item44,Page103)Themethodologyusedtoestimatethetransportof"brousdebrisfromallpotentialbreaklocationsisrealisticandconservative,asshowninthediscussion thatfollows.Table2ofRound1,SSIB-III-4ResponseillustratesametricofLDFGcon-gestionpercentforeachbreakcategory.Thiscongestionmetric(Round1,SSIB-III-4Response)wasasupplementalmetrictosupporttheimplementationof thesteamgeneratortransportfractionforallbreaksinLAREncl.4-3.Thecon-gestionmetricwasnotusedtodeterminethedebristransporttothestrainer (referredtoastransportfractions).Inessence,LDFGcongestionmaynotbe themetricthatdominatesthelikelihoodofdebrisreachingthestrainerbased onbreaklocation,andinRound1,SSIB-III-4,responseitwasintendedasa secondary,supplementalobservation.Table1below,(alsoTable1ofRound1,SSIB-III-4)illustratesthetotaltransportfractionsfromthe"velargebreakscenariosexaminedinthedebris transportcalculation(i,Section6.0,Table6.0.86.0.13,Pg.159164).Note thatthesearetheresultsofthemaximumtotaltransportvalues.WiththesoleexceptionofbreaksoccurringbelowtheSGCompartment,theoveralltransportfractionsassociatedwithIndividualLDFGandSmallLDFG forbreaksintheSGCompartmentareequaltoorgreaterthantheoverall transportfractionsassociatedwithIndividualLDFGandSmallLDFGforother breaklocations.At"rstglance,thismayimplythatusingoveralltransport fractionsassociatedwithbreaksintheSGCompartmentforbreaksthatoccur belowtheSGCompartmentforIndividualLDFGandSmallLDFGwouldyield anun-conservativeassessmentoftheee.g.,strainerheadloss,ofbreaksTuesday1 stMarch,2016:19:32,Page359of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:OverallDebrisTransportFractionsBreakLocationRegionIndividualLDFGSmallLDFGLargeLDFGLatentSGCompartment99%42%1%95%BelowSGCompartment99%60%7%95%

PressurizerCompartment97%31%1%91%

PressurizerSurgeLine97%30%1%91%

RHRCompartment97%30%2%91%

Annulus97%33%8%91%thatoccurbelowtheSGCompartment.However,only278ft 3ofLDFGexistsbelowtheSGCompartment(iii.).EvenifallLDFGbelowtheSGCompartmentfailedandtransported,i.e.,the overalltransportfractionwas1.0,therewouldnotbeenoughdebristocause failureinafullrisk-informedevaluation,(seeSSIB-45fTable3whichgivesthe minimumamountof"bergeneratedthatcausesaCASAGrandescenariotogotofailureof325ft 3fortheallpumpsactivebaseCase1).Therefore,usinganapparentlynon-conservativeoveralltransportfractionforbreaksoccurring belowtheSGCompartmentisofnopracticalrelevance.Ontheotherhand,using overalltransportfractionsforIndividualLDFGandSmallLDFGassociatedwith breaksintheSGCompartmentforallbreaklocationsisconservativebecause(1) thetransportfractionsforIndividualLDFGandSmallLDFGforbreaksinthe SGCompartmentwereconservativelyderived,and(2),transportfractionsfor Individual"ne"berLDFGandSmallLDFGforbreaksintheSGCompartment exceedthoseassociatedwithotherbreaklocations;seeTable1.Table1showsthattransportfractionsforLargeFiberassociatedwithbreaksintheRHRCompartmentandAnnulusexceedthetransportfractionforLarge FiberassociatedwithbreaksintheSGCompartment.However,themaximum total"ber,includingallsizes,associatedwiththebreaksintheRHRCompart-mentandAnnulusare299.4ft 3and79.4ft 3,respectively.SimilartothecaseaboveforbreaksthatoccurbelowtheSGCompartment,evenifallLDFGasso-ciatedwiththebreaksintheRHRCompartmentandAnnulusfailedandtrans-ported,i.e.,theoveralltransportfractionwas1.0,therewouldnotbeenough debristocausefailureinafullrisk-informedevaluation.Therefore,usinganap-parentlynon-conservativeoveralltransportfractionforbreaksoccurringinthe RHRCompartmentandAnnulusisofnopracticalrelevance.Inconclusion,usingtransportfractionsassociatedwithbreaksintheSGCompartmentforbreaksinallregionsofcontainmentresultsinadequateand conservativeestimatesoftransportforallcaseswheretheacceptancecriteria forsumpheadlossmaybechallenged.Thefollowingdiscussionillustratesthatthemethodologyusedtodeterminetransportfractionsresultedinrealisticandconservativetransportfractions.ThedebristransportfractionswerecalculatedinLAREncl.4-3,Reference23.AsstatedintheresponsestoRound1RAIs,thiscalculationwasrevisedTuesday1 stMarch,2016:19:32,Page360of393 DRAFTPART4.RAIRESPONSES(ROUND2)toRevision3(i.)whichissummarizedbelowwhilehighlightingconservatismsandassumptions.Debristransportistheestimationofthefractionofdebris thatistransportedfromdebrissources(breaklocations)tothesumpstrainers.

Sincerisk-informedmethodologyexaminesnumerousweldsincontainment,the transportfractionsaredeterminedasafunctionofbreaklocationasspeci"ed below.*Breaksinthesteamgeneratorcompartments

• Breaksinthereactorcavity

• Breaksinsidesecondaryshieldwall(ISSW)beneathsteamgeneratorcom-partments*Breaksinthepressurizercompartment

• Breaksoutsidesecondaryshieldwallinthepressurizersurgeline

• Breaksoutsidesecondaryshieldwallintheresidualheadremoval(RHR)compartments

• BreaksoutsidesecondaryshieldwallintheannulusDebristransportissubdividedinto"vemodesorphaseswhichare:

• Blowdowntransportthetransportofdebrisbythebreakjet.AsstatedintheRound2,SSIB-III-6aresponse,blowdowndoesnotcapturedebris (orreducetheamountofdebrisavailablefortransport).Blowdownesti-matesthelocationofdebriswhileaccountingforobstructionsthatcause debristoberetainedinthecompartmentofbreakorigin.Thisblowdown phenomenonisreferredtoascaptureinthisRAI,butitdoesnotre-ducetheamountofdebrisavailablefortransportinsubsequenttransport modes.-Blowdownwasindependentlydeterminedforeachbreaklocationduetothevarianceofthe"owobstructions.

-Blowdowntransportsdebristouppercontainment,thecontainmentpool,anddebrisretainedinthecompartmentofbreakoriginwhich iscalculatedby:Transporttouppercontainment-thevolumeratioofuppercon-tainmenttoallofcontainmentandisadjustedbythedebristhat willbecapturedby"owobstructions.Transporttothecontainmentpool-thevolumeratiooflowercontainmenttoallofcontainmentandisadjustedbythedebris thatwillbecapturedby"owobstructions.Debrisretainedinthecompartment-oneminusthedebristrans-portedtouppercontainmentminusthedebristransportedtothe containmentpool.Tuesday1 stMarch,2016:19:32,Page361of393 DRAFTPART4.RAIRESPONSES(ROUND2)

-Table2displaystheblowdowncapturefractionsoftheDDTSandtheimplementedcapturefractionsforthedebristransportcalcula-

tion.Table2:BlowdownCaptureFractionsCEESICapturePercentageforWettedTestsCapturePercentageImple-mentedI-Beams&Pipes7%to14%0%V-Grating21%to36%

SplitGrating16%to29%5%

ContinuousGrating4%to29%Bend3%to31%3%

• Washdowntransportthetransportofdebrisbycontainmentsprayandbreak"owwheredebrismaybecapturedbyonlygratings.Toreiterate, washdownhasthepotentialtoreducetheamountofdebrisavailablefor transporttothestrainersbecausedebrismaybeheld-uporcapturedby gratings.ThisphenomenonisreferredtoascaptureinthisRAI.Thefol-lowingisalistofconservativisms,assumptions,andmethodologiesused inthedeterminationofthewashdowntransportfractions:

-Washdowntransportfractionsaredeterminedforuppercontainmentandbreaklocationswheredebrisremainsinthecompartmentand aresubjectedtothecontainmentsprays;i.e.,thesteamgenerator compartment.

-LDFG"nesarenotcapturedbygratings.Therefore,100%of"nestransporttothecontainmentpool.

-Fornon-"nedebris,<1%to48%ofdebrispassesthroughthegratingperTable4-3oftheDDTS.Thetransportcalculationimplementeda gratingpassthroughof50%forthe"rstgratingandagratingcapture of0%foreachadditionallevelofgrating.

-Thesprayswerealsoassumedtoalwaysbeinitiatedforwashdown analysis.*Pool"lltransportthetransportofdebrisbysheeting"owcausedbybreakandcontainmentspray"owstotheemergencycorecoolingsystem (ECCS)sumpsorinactivecavities.

-DuetothelocationoftheECCSsumpsandpossiblebreaklocations,pool"lltransportwasdelineatedintobreaksinsideandoutsidethe secondaryshieldwall.

-Determinedfroma"rstordertialrateequation,andonlytransports"nedebristhatislocatedonthe"oorduringinjection.

-Transportsdebristothestrainersandinactivecavities.Tuesday1 stMarch,2016:19:32,Page362of393 DRAFTPART4.RAIRESPONSES(ROUND2)

• Recirculationtransportthetransportofdebrisfromtheactiveportionsoftherecirculationpooltothesumpstrainerswhichwasdeterminedby computational"uiddynamic(CFD)simulations.Thefollowingisalistof conservativisms,assumptions,andmethodologiesusedinthedetermina-tionoftherecirculationtransportfractions:

-CFDmodelswerenotsimulatedforallthebreaklocations.Alargebreakintheprimaryloopwasassumedtoberepresen-tativeforthesteamgeneratorcompartmentbreak,belowsteam generatorcompartmentbreak,andreactorcavitybreak.Although the"owpathsaresomewhattfortheprimaryloopbreak andthereactorcavitybreak,thisapplicationisconservativebe-causetheenergyofareactorcavitybreakwouldlargelydissipate beforereachingthemainpool.Alargebreakinthesafetyinjection(SI)pumpdischargelineofLoopBwasassumedtoberepresentativeforbreaksinthepres-surizercompartment,pressurizersurgeline,RHRcompartment, andannulus.ThisisreasonablesincetheCFDmodelanalyzes aLBLOCAoutsidethesecondaryshieldwall,andthelargest breakthatwouldoccurinthepressurizercompartmentwouldbe aMBLOCA.-TheminimumLBLOCAcontainmentpoolheightwasmodelled.Thisisconservativebecausetheminimumwaterheightproduceslarger bulkvelocitiesthanacontainmentpoolwithalargerheight(ii.).

-Thetotal"owratesin(viathecontainmentsprayandbreak"ow)andout(viathestrainers)ofthemodelwasthemaximum,twotrain operation"owrateof14,040gpm.

• Erosiontransportthegenerationandtransportof"ber"neserodedfromsmallandlargepiecesofLDFGhelduponstructuresinthepooland uppercontainmentwasassessedusingdatafromtheDDTSstudyand30-daygenericerosiontesting(iv.).Thefollowingisalistofconservativisms, assumptions,andmethodologiesusedinthedeterminationoftheerosion transportfractions:

-Asprayerosionfractionof1%for"ne"bergenerationandtransportwasappliedforallsmallandlargeLDFGdebrishelduponstructures abovethepoolelevation.Thiserosionfractionwasappliedforall breaksizesindependentofwhethersprayswouldrealisticallybeon orforaspeci"cscenario.

-Apoolerosionfractionof7%for"ne"bergenerationandtransportwasappliedtoallsmallandlargeLDFGhelduponstructuresintherecirculationpool.The7%erosionfractionrepresentstheupper boundofthe95%con"denceofthemeanerosionvalue(i.)from generic30-dayerosiontesting(v.).Tuesday1 stMarch,2016:19:32,Page363of393 DRAFTPART4.RAIRESPONSES(ROUND2)

• Themethodologydescribedaboveproducestransportfractionsthatarerealisticandconservative.

References:

ii.ALION-CAL-STP-8511-08.Risk-InformedGSI-191DebrisTransportCalcu-lation.Revision3.6/10/2014.

iii.ALION-CAL-STPEGS-2916-005,ContainmentRecirculationSumpEvalu-ation:CFDTransportAnalysis.Revision3,October21,2008.

iv.ALION-SUM-WEST-2916-01,CADModelSummary:SouthTexasReactor BuildingCADModelforUseinGSI-191Analyses.Revision4,May22,2014.

v.ALION-REP-ALION-1006-04,ErosionTestingofSmallPiecesofLowDen-sityFiberglassDebrisTestReport,Revision1,November7,2011.4.6.3Question45STPResponse:(Item45,Page104)Thefollowupinquiry,Round1RAI,SSIB6a,impliesthatinLAREncl.4-3,duringblowdown,aportionofsmallandlargedebriswasestimatedtobe captured(orheldup)ongrating,includingpartialareagrating,andhencenot susceptibletotransporttothesumpstrainer.Thisisnotthecase.Figuresof"brousdebriscollectedongratingsduringthedrywellintegratedtestsareshownbelow(Figure1)fromNUREG/CR-6369,Vol.2Pgs.3-29, Figure3-22and3-23[1.].Thesetestswereperformedwithstructuralelements assembledtotheprototypicalcongestionlevel.Itisqualitativelysuggestedby the"guresbelowthattheamountofcongestionassociatedwithhomogenous "beraccumulationwouldnotbelargeenoughtogreatly"owresistance throughthegratings.Furthermore,thestudy(NUREG/CR-6369,Vol.2,Pg.

iii.)concludedthatcaptureofallstructureswasfoundtobeaweak functionof"owvelocityandlocal"owpatterns[1.].Figure1:FibrousdebriscollectedongratingsduringthedrywellintegratedetestsfromNUREG/CR-6369,Vol.2,Pgs.3-29Tuesday1 stMarch,2016:19:32,Page364of393 DRAFTPART4.RAIRESPONSES(ROUND2)Toclarify,blowdownanalysisdoneinsupportLAREncl.4-3doesnotusecapturemetricsfromgratingstoreducetheamountofdebrisavailabletotrans-port.Forexample,noamountofdebriscapturedbygratingsisassumedtobe stuck(held-up)andnotavailableforothertransportmechanisms.IntheblowdowntransportphaseinLAREncl.4-3,theonlyuseofgratingcaptureistoestimatetheratioofdebristhatwouldtransporttoupper containmentversusremainingintheSGcompartmentortransportingtolower containment.Noneofthedebrisisassumedtobecaptured(andhencenot susceptibletotransport)eitheronfullareagrating,partialareagratingorother hold-upmechanismsintheblowdownphasecalculation.Instead,afterblowdown phase,allgenerateddebrisisavailableforremainingtransportmodes.Thisis illustratedinthetransportlogicdiagramsinLAREncl.4-3,Ref.[23],wherethe totalgeneratedquantityofdebrisisdistributedbetweenlevelsofcontainment andsubjecttosubsequenttransportmodes.Anexcerptexample,Figure5.12.2-Smallpiece"berglassdebristransportlogictree(SGcompartmentbreak),from LAREncl.4-3,Ref[23],isshownbelow.Tuesday1 stMarch,2016:19:32,Page365of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure2:LAREncl.4-3Figure5.12.2Tuesday1 stMarch,2016:19:32,Page366of393 DRAFTPART4.RAIRESPONSES(ROUND2)Duringtheblowdowntransportphase,theuseofabest-estimategratinghold-upfraction,(asopposedtoalower-boundvalue)resultsinminimizingthe quantityofdebristhatisconsideredtotransporttouppercontainment.Thisis conservativeandhasprecedentfromthesevaluationofNEI04-07Volume2 EvaluationforGRSection3.6.3,Pg.58)whichstatesFormostlycom-partmentalizedcontainments,theGRrecommendsnodebrisbetransportedto uppercontainment[3.].STPscontainmentincludesdirectpathwaystoupper containment;henceincorporationofreductionsindebristransportedtoupper containmentisconservativeAllconsiderationofgratingsintheSTPblowdown transportanalysisreducethefractionofdebrisblowntouppercontainment withoutreducingthequantityofdebristhatremainsavailableforsubsequent transportmodes.

REFERENCES:

1.NUREG/CR-6369,Vol.2.DrywellDebrisTransportStudy:ExperimentalWork.September1999.2.NUREG/CR-6369,Vol.1.DrywellDebrisTransportStudy.September 1999.3.NEI04-07,Vol.2.PRESSURIZEDWATERREACTORSUMPPER-FORMANCEEVALUATIONMETHODOLOGY.Revision0.December20044.6.4Question46STPResponse:(Item46,Page104)IntheRoverDmethodology,itisslightlymoreconservativetoassumethatsmalldebrisiscapturedonstructuresandcalculatedtoerode,therebyadding tothe"ne"bertransportedtothesumppool.Thefollowingresponsesupports theoriginalSTPmethodologyfordebristransport.Basedonthediscussionthatfollows,thereisnobasisforassumingthatwashdownof"brousdebristhroughgratingswouldincreaseabovethatfound duringtheDDTSifthewashdowntimeissigni"cantlyincreased.Section4.4.1,Con"rmatoryTests,oftheDDTS(Volume2,Pg.4-5)includesthefollowingconclusions:#2.MostoftheSmalldebrispieceswillbewasheddownbywaterwithin"rst10-15minutesafterwhichwashdownreachesanasymptote.#3.Largepieceswillnotbeforcedthroughthegratingevenathigh"ows.Theywillremainonthegratingandmayerodewithtime.Erosionalsoexhibits anasymptoticbehavior.TheSmalldebriscategoryintheDDTS(Volume2,4-3)isdescribedasalight,loose,andwell-aeratedtexturewithanaveragedensitylowerthan0.25

Ibm/ft 3usuallyconsistingoflooseclustersofindividual"bers.Typicallythesepieceswereabout1.5"insizeandpossessedlittleoftheoriginalstructureor thechemicalbinding.

...TheMediumcategoryintheDDTSisdescribedasInsulationdebrispre-tornfromtheblanketbyanair-jetimpingement.These pieceskeepsomeoftheoriginalstructuresintheinnerregions,whiletheylook torn-downorlooseontheoutside.Typicallythesepiecesareabout6"x4"in dimension.Tuesday1 stMarch,2016:19:32,Page367of393 DRAFTPART4.RAIRESPONSES(ROUND2)Thesizedistributionusedinthecurrentanalysesarebasedon(proprietary)ALION-REP-ALION-2806-01,Rev:3.Thesizedistributioncategoriesare:Fines (IndividualFibers),SmallPieces(<6"onaSide),LargePieces(>6"onaside)andIntact(covered).TheSmalldebriscategoryintheDDTScorrespondstotheFinescategoryinSTPcalculationsonthebasisthattheclumpsarecollectionsofindividual "berswithlittleoftheoriginalstructure.TheMediumcategoryintheDDTScorrespondstotheSmallPiecescat-egoryinSTPcalculations.Debrisinthiscategoryisgenerallylargerthanthe gratingvoidsizesandhenceisnotexpectedtobebewasheddownbywater within"rst10-15minutesasdescribedinDDTSSection4.4.1,Con"rmatory Tests,conclusion#2,above,aswasthecaseforSmallDDTSdebris.STPSmallPiecesdebrisbehaviorcorrespondstoDDTSSection4.4.1,Con-"rmatoryTests,conclusion#3,

...willnotbeforcedthroughthegratingevenathigh"ows

...ItisnotedthatthisDDTSconclusiondoesnothaveanylimitationswithrespecttotime.DDTS4.5,SummaryandConclusions,itemsstates:2.Asigni"cantfractionofthemediumpieces(generatedbyjetimpactoninsulationblanket)wouldbe erodedandtransportedtothedrywellpool.Atransportfactorof1.0isrecom-mendedinthecaseofbreakover"ow(e.g.,followingarecirculationlinebreak);

ontheotherhand,forspraysatransportfactorof0.5appearsreasonable.The DDTSrecommendationforthesprays-relatedtransportfactor,0.5,whichwas usedasthebasisforthewashdowntransportfractioninSTPdebristransport washdowncalculations,doesnotincludeany"owduration-relatedrestrictionor

cautions.TheveryfactthatDDTSwashdownanderosiondiscussionisfocusedpri-marilyonerosionindicatesthatwash-throughfordebrisoftsize,i.e.,

greaterthanthevoidspaceofgrating,isnotexpectedtobeanissuewithin anextendedpost-LOCAtimeframe.Onthecontrary,eventhetimeframeof erosion,whichcanonlyhappenifdebrisremainsretainedongrating,issaidto beasymptoticafterashortperiodofexposureto"ow.Onthebasisofthediscussionabove,thereisnobasisforassumingthatwashdownof"brousdebristhroughgratingswouldincreaseabovethatfound duringtheDDTSifthewashdowntimeissigni"cantlyincreased.4.6.5Question47STPResponse:(Item47,Page104)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.6Question48STPResponse:(Item48,Page105)Tuesday1 stMarch,2016:19:32,Page368of393 DRAFTPART4.RAIRESPONSES(ROUND2)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.7Question49STPResponse:(Item49,Page105)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.However,the correctvalueofCSHLforuseincalculationsis1.952ft.4.6.8Question50STPResponse:(Item50,Page105)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.9Question51STPResponse:(Item51,Page106)Vortex,AirIngestion,andVoidFractionTheDecember2008submittalinresponsetoGL2004-02discussedthepoten-tialforvortexing,airingestion,andvoidformationfortheSTPsumpstrainers madebyPCI.STPstrainerprototypetestingatAldenResearchLaboratory veri"edthattheminimum1/2in.submergencewouldprecludeairingestionor vortexdevelopment.SubsequentdiscussionwasheldwiththeNRCsduring theSeptember13,2010publicmeetingconferencecallconcerningRAIs.The NRCnotedthatvortexingisnotlikelytobeanissueforPCImadestrain-ersbasedontestingbySTPandothersthatshowvortexeswillnotoccurfor conditionsboundingtheSTPconditions.Duetolackofanairentrainmentmech-anism(i.e.vortexformation)alongwithcompletesubmergenceofthestrainer, airingestionisnotexpectedtooccur.AlsodiscussedintheDecember2008 submittalwasanevaluationofvoidfractionthatconcludedthat"ashingand subsequentvoidfractionformationwouldnotoccuracrossthestrainer.Thevortex,airingestion,andvoidfractionanalysisconcludedthatvoidfrac-tionoccurringatthestrainerdebrisbedduetoheadlossandtheaccompanying post-LOCAconditionswouldbereversedandanyvoidswouldhavecollapsed beforethestrainerdischarge"uidleftthecontainmentsumpandenteredtheTuesday1 stMarch,2016:19:32,Page369of393 DRAFTPART4.RAIRESPONSES(ROUND2)ECCS/CSSinletpipe.Thenetvoidfraction(i.e.,netairproduction)isthere-fore0%.Therefore,voidfractionisnotanissueforanyofthepost-LOCA"uid associatedpressureandtemperaturecombinationsassociatedwiththesubject "uid"owfromthestrainertotheECCS/CSSinletpipe.TrappedAirinPlenumBoxThestrainercon"gurationissuchthatsumpwatergoesintothestrainermoduleandthengoestothecoretubewhereitisdirectedtotheplenumbox.

Therearefourinletstotheplenumbox(oneforeachconnectedstringofstrainer modules).Theplenumboxcollectsthedischarge"owfromthestrainermodules anddirectsthe"owdownwardtothesumppitwhichcontainstheinletofthe suctionpipetotheECCSandCSSpumps.Vortexbreakersareinstalledinthe sumppitaroundtheinlettothesuctionpipe.Upon"oodingofthestrainermodulesandthesumppitduringtheinitialpost-LOCApool"ll-upphase,someairmaybetrappedunderthecoverofthe plenumbox.Thisairdoesnotconstituteablockageofwater"owfromthe strainerstothesumppit.Anytrappedairintheplenumboxdoesnotincrease thecleanstrainerheadlossorinterferewithwater"ow.Thetrappedairwill slowlydissipateduringoperationoftheECCSandCSSpumps.

NoteTheresponsetothe1stRoundRAIreferredtoadocumentconcerninggasvoidsinthepipingbetweenthesumpstrainersandthesafetyinjectionpumps andcontainmentspraypumps.Thisdocument(Reference58)waspreparedby MPRforSTPinresponsetoGL2008-01ManagingGasAccumulation.Itis acalculationthatdeterminesthemaximumacceptablegasvoidvolumesfor particularlocationsinECCSandRHRpipingbasedonindustryacceptance criteriaforthegasvolumesallowedtotransporttothesystempumps.Sinceit isnotconcernedwithsumpstrainerperformanceandisgermaneonlyforgas accumulationmanagement,itshouldnotbepartoftheresponsetothisRAI.4.6.10Question52STPResponse:(Item52,Page106)ThewaterlevelcalculationforRoverDusesthedeterministicevaluationofwaterlevelthatwasdescribedintheDecember2008submittalfortheGL2004-02response(ML083520326).Thiswasthebasisforthetestingthatshowed acceptablesubmergence.SeeresponsetoRAI31thatexplainsvortexing,deaer-ation,and"ashingwillnotoccurisbasedontestingandconservativeassump-tionsinthelevelcalculation.Thetransportevaluationisalsodescribedinthe December2008submittalandisconsistentwiththesumplevelevaluation.4.6.11Question53STPResponse:(Item53,Page106)Theminimumandmaximumvaluesusedfortwotrainoperationwere1932and2350gpmrespectively(Volume3,Section2.2.8).Theminimum"owrate (1932gpm)usedfortwoandthreetrainsoperablescenarioswastakenfrom STPsDESIGNBASISDOCUMENTCONTAINMENTSPRAYSYSTEM (Volume3Ref.42,Pg.A-40).This"owrateistheminimumprobable"owrateTuesday1 stMarch,2016:19:32,Page370of393 DRAFTPART4.RAIRESPONSES(ROUND2)pertraincalculatedusingFLOMAP(Volume3Ref.42,Pg.A-40).Thismini-mum"owratewascalculatedwiththefollowingsimpli"cationsandassumptions.

• Pipingand"ttingresistancesbasedoofplantcon"gurationandCrane410methodology

• 5percentdegradedpumpcurve

• Maximumcontainmentdesignpressure

• MinimumTechSpecRWSTlevelThemaximum"owratepertrain(2350gpm)usedfortwoandthreetrainsoperablescenarioswastakenastheFLOMAPcalculatedaverageofdesign"ows fortrainsAandBoperationduringrecirculation(Volume3Ref.42,Pg.A-39).TheminimumandmaximumuserenteredvaluesforonetrainCSoperationwere2080and2600gpmrespectively.Themaximum(2600gpm)"owratefor onetrainoperationwasspeci"edinVolume3Ref.41,Pg.16.Theminimum value,foronetrainoperation,wastakenas80%ofthemaximumvalue(Volume 3Ref.41,Pg.16);wherethe80%scalingwastakenastheratioofminimumto maximum"owratefromthetwotrain"owcase.SamplingCS"owratesforeachscenariosrespectiveoperabletrainstateisappropriatebecausenopreferencewasadded(randomandequallyprobable) betweentheminimumandmaximum"owratevalues,andbecauseminimumval-ueswereselectedorscaledtorepresentprobableoutcomes.Selectionofrandom "owratesbetweenminimumandmaximumlimitsisacommonapproachforrig-orousuncertaintypropagationincaseswherephysicalvariabilityorcompeting mechanismsprecludede"nitiveselectionofconservativeparametervalues.Con-tainmentsprayrateissampledinthiscasebecause(1)therearenoinitiating-eventspeci"c(breaksizedependent)"owratesavailablefortheCSpumps;(2)

CS"owsaremostdependentoninitiating-eventindependentparameterssuch astheRWSTlevel,initialpumpsavailable,andvarianceinpumpperformance thatCS"owwithintheappliedranges;and(3)"beraccumulationrate inthefuelisbythe"owsplitdivertedtosprays,soallprobableranges ofCS"owrateshouldbeexercisedtodeterminethequantitativeimpactonall failuremodes.4.6.12Question54STPResponse:(Item54,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.Flashingwas addressedinSTPNOCsDecember11,2008,letter(ML083520326).Tuesday1 stMarch,2016:19:32,Page371of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.6.13Question55STPResponse:(Item55,Page107)StrainerbackwashfromtheRWSTisinitiatedfromSACRG-2(SevereAcci-dentControlRoomGuidelineAftertheTSCisFunctional),Addendum2(which directsenteringSAG-3)aftertheTSCisactivatedbydirectionthroughtheTSC Diagnostic"owchartwhentheCETsindicategreaterthanF.Furtherguid-anceisgiveninStep5.b.4ofSAG-3(InjectintotheRCS)foroperationwith RWSTinbackwashalignment.4.6.14Question55aSTPResponse:(Item55a,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforchemical orheadloss.Headloss,includingchemicalisaccountedforintheplant-speci"cdeterministictesting.4.6.15Question56STPResponse:(Item56,Page107)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.16Question57(a)STPResponse:(Item57a,Page108)RoverDdoesnotusethe"ltrationmodelusedinCASAGrande.RoverDusesitsown"ltrationmodelthatassumesno"beronthesumpscreenatthe startofrecirculation.InRoverD,STPdirectlyappliesmeasuredtestdatain-cludingtheuncertaintybounds(obtainedfrommeasurements)toaccountfor bypassuncertainty.Thedataare"ttotheupper,central,andlowerboundof measurementuncertainty.Assumingno"beronthestrainerwhenrecirculation beginsshouldmaximizetheamountof"berpenetrationtothecore.4.6.17Question57(b)STPResponse:(Item57b,Page108)RoverDdoesnotusethe"ltrationmodelusedinCASAGrande.RoverDusesitsown"ltrationmodelthatassumesno"beronthesumpscreenatthe startofrecirculation.4.6.18Question57(c)STPResponse:(Item57c,Page108)Tuesday1 stMarch,2016:19:32,Page372of393 DRAFTPART4.RAIRESPONSES(ROUND2)InRoverD,STPdirectlyappliesmeasuredtestdataincludingtheuncertaintybounds(obtainedfrommeasurements)toaccountforbypassuncertainty.The dataare"ttotheupper,central,andlowerboundofmeasurementuncertainty.

tconditions(forexample"owratesandconcentrations)areincluded inthemeasuredtestdataandappropriatelyaccountedforintheuncertainty boundsofthe"ttothedata.Thetestdata"tforthetboundsisshowninthe"gure.STPPCIStrainerdatashownwith"ltration"tsfromtestmeasurementsatdtlevelsof"beraccumulationshownas"tstolowerboundofdata,central"tofdata,and upperbound"tofdata.4.6.19Question57(d)STPResponse:(Item57d,Page108)Anactualstrainermodulewasusedtoperformtestinginordertoeliminateconcernsrelatedtothecomplexdesignofthestrainersurface.tapproach velocitieswereusedaswellasdtconcentrations.Testmeasurementsfrom sixtestswereusedto"tthedataboundsofthedata.Asdescribed,otherresponses,theuncertaintyboundsofthetestmeasure-mentsaredirectlyevaluatedintheRoverDapproachasshowninAttachment

7.4.6.20Question57(e)STPResponse:(Item57e,Page109)TheRoverDstrainerbypasscalculationusesimplicit(Adamsmethod)in-tegrationofthemassconservationequations.Themethodiswell-knownasa robustsolverfornordinarytialequationsandisnotsubjectto timestepsizeissuesassociatedwithexplicitmethods.Themethodandequations areclearlydevelopedandexplainedinAttachment7.Tuesday1 stMarch,2016:19:32,Page373of393 DRAFTPART4.RAIRESPONSES(ROUND2)STPPCIStrainer"ltrationfractionsfromtestmeasurementsatdtlevelsof"beraccumulationshownas"tstolowerboundofdata,central"tofdata,andupperbound "tofdata.4.6.21Question57(f)STPResponse:(Item57f,Page109)TheRoverDstrainerbypasscalculationusesthemeasuredtestdatadirectlyintheequationsshowninAttachment7.Theparametersusedareshownin Attachment7alongwiththeinputsusedinuncertaintyboundcalculations.4.6.22Question58STPResponse:(Item58,Page109)Theapparentdiscontinuityresultsfrompipesbeingofdiscretesizesandthattherearevaryingnumbersofthedtsizepipes.Seethetablebelow.Thereare15discretepipesizesatSTP,andatotalof628weldlocationswhereabreakcanoccur.Ofthese15discretepipesizes,breaks13inchesand largercanonlyoccuron3ofthem(20%).Ofthe628weldlocations,breaks 13inchesandlargercanonlyoccuron64ofthem(10.2%).Inaddition,CASA Grandeissetuptosamplelargerbreaksatagivenlocationmorefrequently thansmallerbreaks,sowewouldexpecttoseerelativelyfewbreaksbetween13 and20inchesontheselargerpipes.Inconclusion,thebreaksizesgoingtofailurearerepresentativeofthepipesizesattheSTPpowerplantandthelikelihoodofbreaksonthosepipes.The indicatedthatthebehaviormaybenon-physical,wheninfact,thisbehavior isafunctionofthe15discretebreaksizesatSTPandthefactthatsmallerbreaks arelesslikelytofailthanlargerbreaksTuesday1 stMarch,2016:19:32,Page374of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table1:PipeSizesatSTPandtheNumberofWeldsAssociatedwithEachPipeSizeSTPPipeSizesSTP#ofWelds0.614320.8153 1.3389 1.68985 2.1256 2.62626 3.43890 5.189886.81354 8.50030 10.126131 12.81410 27.50016 29.00020 31.00028 6284.6.23Question59STPResponse:(Item59,Page109)Forclaritythisresponsehasbeenbrokenupintothreemajorsections:1)ImportofCADGeometryintoCASAGrande,2)ValidationofCASAGrande DebrisGeneration,and3)Conclusions.ImportofCADGeometryintoCASAGrande:

Therearefourtypesofgeometry(PipeExtractInsulationData,EquipmentInsulationdata,ConcreteandSteelStereolithography"les)thatcanbeimported intoaCASAGrandesimulation.Thesefourtypesofgeometryanddescriptions ofhowtheyareimportedandusedintheCASAGrandesuitearedescribed below.PipeExtractInsulationData:PipeExtractdataisextractedfromthepip-ingassemblyinthe3DcontainmentCADmodelbyaproprietaryAutoDesk Inventoradd-in(createdbyAutoDeskforAlion)andincludesallinformation aboutpipingandpipinginsulationneededtorebuildthepipinginsulationgeom-etrynumericallyinsideofCASAGrande.Speci"callyPipeExtractdataincludes pipesegmentlengths,pipenames,pipeinsulationtypes,Cartesiancoordinates ofextractedpointsonpipes(Work-Point),bendradiiofextractedWork-Points, innerandouterdiametersofpipes,andWork-Pointtypes(ie.valve,hangar, weld,etcÉ).AnexampleofapipesegmentinaPipeExtractinput"leisshown belowinFigure1.ThedatafromeachpipesegmentinthePipeExtract"leisreadintoCASAGrandeandusedtocreateanumericalreconstructionofthepipinginsulation volumeswithpointvolumescalledvoxels.Theusercanspecifythenumerical resolutionofthepipinginsulationreconstruction(withvoxels)intheCASATuesday1 stMarch,2016:19:32,Page375of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure1:PipeExtractFileDataExample.Grandesimulationbyde"ninglinearresolutionandnumberofazimuthalbinsintheinputdeckFigure2.Figure2:ResolutionInputsforCASAGrandePipingReconstructionAnexamplereproductionofPipeExtractdatausingtheaboveuserde"nedlinearresolutionandnumberofazimuthalbins(Figure2)isshownbelowin Figure3.Noticethatthereare12bandsthatrunthelengthofthepipecurve whichshowtheazimuthaldiscretizationofthevoxelsintobins.Eachpointonthe bandsisinoneazimuthalbinandapproximatelysixinches(LinearResolution) awayfromotherpointsonthesameband(with"exibilityinlineardiscretization toaccountforcurvature).SpotchecksaredoneonsegmentsofpipinginsulationwitheachnewsetofTuesday1 stMarch,2016:19:32,Page376of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure3:CASAGrandeRepresentationofCurvedPipeSegmentPipeExtractdatathatisloadedintoCASAGrandeusingtheCADsoftwaresgeometryasthebaselineforcomparison.TheInventor2013representationof theinsulationsegmentisshownbelowinFigure4Figure4:Inventor2013CADRepresentationofExampleSegmentWhenthevolumeoftheCASAGrande(3.2300E4in 3)andInventor2013CADrepresentation(3.0954E4in 3)oftheinsulationsegmentwerecomparedthepercentdbetweenthevolumesforthisexamplewasfoundtobe4.25%.1.EquipmentInsulationTextFiles:TheequipmentinsulationimportformathasbeenupdatedsinceV1.6ofCASAGrandetothemoreaccurateinput formatintroducedinV1.7.Thisequipmentinsulationformatrequiresthe usertosupplyatext"leforeachpieceofequipment;wherethedataof theequipmentinsulationtext"lecontainsx,y,zlocations(inches),point volume(V)value(in3)andinsulationtypeforeachofthevoxelsthatdis-cretizeequipmentinsulation.AnexampleofinputfromanSTPequipment insulationtext"leisgivenbelowinFigure5;wherethedataineachrow isformattedtoreadx,y,z,V,andInsulationTyperespectively.BecauseofthesimplicityoftheEquipmentinsulationformatthese"lescanTuesday1 stMarch,2016:19:32,Page377of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure5:Exampletextfromequipmentinsulationinput"lebecreatedinanExcelspreadsheet.ForSTPhoweverthese"leswerecreatedfromSTLexports(forhighresolution)ofequipmentfromtheCADsoftware.

TheseSTL"leswerethenpre-processedtosupplytheCartesiandatasumma-rizedinFigure5.Notethatitisalsopossibletoimportpipinginsulationorany otherinsulationintothemodelusingthisinputmethod.1.ConcreteStereolithography(STL)"le:Theconcreteinput"leisabinarySTLdata"lecontainingallCADgeometryoftheplantconcretestruc-tures.TheconcreteSTL"leisusedtorepresentrobustbarriers(insulation shielding),andforconcretecoatingsdestruction.TheconcreteSTL"leis interpretedasacollectionofsurfacetrianglefaces(facets)andrespec-tiveunitsurfacenormalsinthreespace.Forconcretecoatingscalculations thesetrianglesarere"nedtoauserspeci"edsurfaceareatoensurethat coatingsquantitiesarecalculatedaccurately.Asanexample,apictureoftheCASAGrandereconstructionoftheSTPconcreteSTLdataisshownbelowinFigure6.Notethatthisimageisthedirectimportusedasde-structionbarriersanddoesnotrepresentre"nementsmadeforquali"ed coatingsdestruction.Whentheconcrete"leisimportedintoCASAGrandethe"leisvisuallyinspectedforerrors.Firstthemodelischeckedtomakesurethattriangles arentvisuallyoverlapping.NotethatthereisanumericalSTLchecker inCASAGrande,butthevisualinspectionisforaddedprotectionagainst STLdatainterpretationerrors.Nextthetrianglenormalvectorsarevi-suallyinspectedtomakesurethattheyarepointingoutofthesurface.

ThesechecksinsurethattheCASAGrandeinterpretationoftheconcrete "lewillcorrectlysimulatebarriersbetweenbreaksandinsulationtargets.2.SteelSTL"le:Thesteelinput"leisabinarySTLdata"lecontainingallTuesday1 stMarch,2016:19:32,Page378of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure6:CASAGrandereconstructionofconcreteSTLinput"leCADrepresentationsofplantsteelstructures.ThesteelSTL"leisonlyforsteelcoatingsdestructioncalculations;steelstructuresarenotusedfor insulationshielding.ThesteelSTL"leisimportedinCASAGrandein thesameformatastheconcreteSTL"le.Forcoatingscalculationsthese trianglesarere"nedtoauserspeci"edsurfaceareatoensurethatsteel coatingsquantitiesarecalculatedaccurately.Formostplantsanalyzedthe userspeci"edtrianglere"nementsurfaceareaissetto16in2whichgives goodre"nementoverthebreakspectrum.Anycoarserre"nementarea speci"edwilldecreasesimulationruntimebutwillbelessaccurate.ValidationofCASAGrandeDebrisGenerationTheSTPCASAGrandeinputgeometryhasbeenveri"edforimportaccu-racy,andcalculateddebrisgenerationinCASAGrandehasbeenbench-marked againstCADcalculatedvalues.ImportaccuracychecksinCASAGrandehave beenautomated.AlineisavailabletoassigntheCADcalculatedtotalvolume ofeachimportedinsulationtypeintheinputdeck(DebrisVolumefromCAD ModelinputinFigure7Below).WhenrunningCASAGrandetheuserenteredDebrisVolumefromCADModelinputvalue,iscomparedtoitscorrespondingimportedinsulationtype.

Thiscomparisonisautomaticallywrittentoa"leintheoutputsofthesimu-lationintheCASAvsCADInsulVol.txttext"le,andcanbedirectlyprocessed asacommondelimited"leinExceltogiveacomparisontable.STPsimport comparisontableisshownbelowinTable1.ExaminingtheCASAGrandeautomatedimportcomparisonfortheSTPgeometry,itcanbeseenthatallinsulationtypevolumeshavebeenconserved within2%.Tuesday1 stMarch,2016:19:32,Page379of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure7:DebrisVolumefromCADModelinputTable2:STPCASAGrandeVs.CADinsulationvolumesimportcomparisonDebrisTypeCADInsulationVolume(ft 3)CASAGrandeIn-sulationVolume (ftft 3)Ratio(CASA/-

CAD)Low-Density Fiberglass (LDFG)9893.4989729.78670.98345Microtherm24.89324.89220.99997Insulationdebrisgenerationhasbeenbench-markedforvalidationusingaDEGBbreakatSTPweld31-RC-1402-NSS-RSG-1D-ON-SE.TheCADmodel InsulationdebrisgenerationvalueswerecalculatedbyaCADanalystusing BooleanoperationsavailableintheAutoDeskInventor2013software.Asideby sidecomparisonofpicturesfromthedebrisgenerationcalculations(forNukon) performedinCASAGrandeandbytheCADanalystisshownbelowforqual-itativeinspectioninFigure8.Noticethatinbothpictures(Figure8leftand right)interferenceoftheZOIwithpipingishighlightedinred.Tuesday1 stMarch,2016:19:32,Page380of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure8:CASAGrande(left)VsCAD(right)debrisgenerationpicturesResultsforCASAGrandeVs.CADcalculatedSTPinsulationdestructionoverallinsulationdebristypesforaDEGBbreakonweld31-RC-1402-NSS-RSG-1D-ON-SEaregivenbelowinTable2.Table3: default InsulationTypeZOISizeCADDebrisVolume(ft 3)CASAGrandeDebrisVolume (ft 3)PercentD enceMicrotherm28.6D0.0131.7197.07.0D317.2326.32.811.9D553.6578.44.4Nukon17.0D810.2829.72.47.0D295.0283.44.0ThermalWrap11.9D623.3606.62.717.0D1,134.81,138.70.3AllSTPinsulationdestructionamountscalculatedinCASAGrandearewith5%ofthevaluescalculatedinCADexceptforMicrotherm.AlthoughtheMi-crothermdebrisgenerationvaluescomparedbetweenCADandCASAGrande calculationsshowalargepercentdthemagnitudeofthedestroyed Microthermquantitiescalculatedareverysmallincomparisontothosecalcu-latedforNukonandThermalWrap.Notethatcalculationsthatresultinsmaller amountsofcalculateddebrisaresubjecttohigheruncertaintyinsideoftheCAD model(SeepercentdforMicrotherminTable2);wheremanyofthese debrisarelocatedinsmallpenetrationsandrequireaconsiderationfromthe CADanalystwhethertheyshouldbeincludedornot.AsimilarvalidationhasbeenperformedforcoatingsquantitiesusingtheSTPmodel.ThisvalidationuseduntypicalZOIsizesbutgivesacomparison betweenCADandCASAGrandecalculatedquali"edcoatingsvalues.Results ofthecomparisonaregivenbelowinTable3.InTable3thereisgoodagreementbetweentheCASAGrandecalculatedTuesday1 stMarch,2016:19:32,Page381of393 DRAFTPART4.RAIRESPONSES(ROUND2)Table3:CASAGrandeVs.CADcalculatedquali"edcoatingsdebrisgenerationquali"edcoatingsdebrisquantitiesforconcreteandsteelat31-RC-1402-NSS-RSG-1D-ON-SE.Notethatcalculationsthatresultinsmalleramountsofcal-culatedquali"edcoatingsdebrisaresubjecttohigheruncertaintyinsideofthe CADmodel(similartoinsulation);wheremanyofthesedebrisarelocatedin locationsthatrequireaspecialconsiderationforinclusionbytheCADanalyst.

Alsonotethatcalculatedquali"edcoatingsdebrisquantitiescanbere"nedby changingtheareadiscretizationparameterintheinputdeckforType2debris.ValidationofCASAGrandedebrisgenerationroutineshavealsobeensuc-cessfullyperformedforotherplantsgeometries,buthavenotbeenincludedin thisresponsebecauseconsenthasnotbeenrequestedfortheiruse.

Conclusions ValidationoftheimportofSTPsinsulationgeometryintoCASAGrandehasbeenperformedbycomparisontototalvolumesintheAppendixBdevel-opedSTPCADmodelforeachinsulationdebristype.Thisimportcomparison forinsulationvolumeconservationisautomatedintheCASAGrandesuiteand isperformedatthebeginningofeachnewsimulation.CASAGrandedebris generationroutinesforbothinsulationandquali"edcoatingsdestructionhave beenbench-markedtoCADcalculatedvalueswhichhaveshownaccurateresults fortheSTPgeometryandotherplantcomparisonsnotreleasedinthisdocu-ment.LargeinCASAGrandevs.CADcalculateddebrisquantities areapparentforsmallmagnitudedebrisgeneration.Thesemaybe theartifactoftheCADanalysthavingtoperformlineofsightdebris generationcalculationsinsideofaCADmodel.Lineofsightcalculationsfor debrisgenerationareautomatedintheCASAGrandesuiteandareaccurateup totheresolutionoftheimportedgeometry.4.6.24Question60STPResponse:(Item60,Page110)RoverDdoesnotusecumulativedistributionfunctionstodeterminetheriskordeterministicfailurecriteria.CASAGrandeisusedinanon-probabilistic way,only"ndingtheamountof"ne"berdebristhatiscreatedandtransported tothesumpwithoutuncertaintydistributions.Theamountof"ne"berdebris transportedincludeslatent"bersanderoded"ber.Tuesday1 stMarch,2016:19:32,Page382of393 DRAFTPART4.RAIRESPONSES(ROUND2)4.6.25Question61STPResponse:(Item61,Page110)Thezoneofin"uence(ZOI)isthevolumeaboutthebreakinwhich"uidescapingfromthebreakhastenergyto generatedebrisfrominsulation,coatings,andothermaterialswithinthezone (1).TheZOIradiusisdependentonthedestructionpressureofagivendebris sourceandisproportionaltotheinternal"uidconditionsandambientconditions ofcontainmentintermsofpressureandtemperature.Inbothsphericaland hemisphericalZOIcalculations,jetre"ectionisaccountedforintheconversion ofanANSIjettoanequivalentsphericalorhemisphericalvolume.TheZOIis representativeofANSIjetpressuresandjetre"ection/impingementpressures foragivenbreakthatwoulddestroyspeci"cdebrissources.TheZOIboundary representsthelowestimpingementpressuretocauseaspeci"cdebrissourceto

fail.HemisphericalZOIsareutilizedintheCASAGrandeevaluationasanap-proximationforlongitudinalbreaks,typicallyfromafailedweldorvalvethat doesnotresultinfullradialandaxialofseveredpipeendsasinthecase ofaDEGB.NEI04-07statestheZOIforlongitudinalbreakscanbesimulated asahemispherewitharadiusdeterminedbythedestructionpressureofthe insulationthatwouldbebythepostulatedbreak(1).Ifaspeci"cinsu-lationfailswithina17.0DZOIforexample,thiscanbeanalyzedasaDEGBon pipewithinnerdiameterofDinwhichtheZOIisaspherecenteredonthe pipeaxis(thebreakdiameterofaDEGBisequaltotheinnerdiameterDof thepipe).Inaddition,theinsulationdebrisgeneratedbyalongitudinalbreakis analyzedwithinahemisphericalZOIofradius17.0DwhereDisthediameter ofthebreakandthe"atfaceoftheZOIistangenttotheoutersurfaceofthe pipe.Boththesphericalandhemispherical17.0DZOIsrepresentthesamejet pressureswithina17.0Dboundaryalthoughtheirshapeandbreaksizesare t.SphericalZOIDbreakdiameter=innerpipediameterHemisphericalZOIDbreakdiameter

<innerpipediameterSimilartosphericalZOIs,robustbarrierspreventjetexpansionforhemi-sphericalZOIsandreducetheencompassingvolumeofthedestructionzone.

AllZOIsaretruncatedatrobustbarrierinterferenceintheCADmodelwhich providesavisualandanalyticalrepresentationofcon"nementtojetexpansion (highenergyjetscannotexpandthroughsolidstructuresandthereforeZOIvol-umesarereducedattheseinstances).Forexample,Figure3showsthereduction ofaZOIvolumethatextendsbeyondarobustconcretewallintheCADmodel.FromNEI04-07Volume2,theZOIrecommendedintheGR[NEI04-07Volume1]Section3.4isasphericalboundarywiththecenterofthespherelo-catedatthebreaksite.TheuseofasphericalZOIisintendedtoencompassthe ofjetexpansionresultingfromimpingementonstructuresandcompo-nents,truncatingthespherewhereveritintersectsanystructuralboundaryor largerobustequipment.TheGRrecommendsthatZOIsizingbedeterminedus-Tuesday1 stMarch,2016:19:32,Page383of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure3:ExampleofZOItruncationatrobustconcretebarrieringtheAmericanNationalStandardsInstitute/AmericanNuclearSociety(AN-SI/ANS)58.2-1988standardforafreelyexpandingjet(ANSI/ANS58.2-1988).

ThebaselineZOIcomprisestheinsulationtypethatgeneratesthelargestZOI ofallpotentiallyinsulationtypes(2).Debrisvolumesgeneratedfromlongitudinalbreaksaredeterminedbycon-strainingthe"atfaceofthehemisphericalZOIperpendiculartothebreakvector andtangenttotheoutersurfaceofthepipe.InCASAGrande,debrisquanti-tiesarecalculatedfromhemisphericalZOIswithrandomlysampled(foreach simulatedbreak)orientationsaroundthepipesurfaceatbreaklocationswith CADinterferences.ThisisperformedsimilartoguidanceinNE04-07Volume1, whichstates,[for]hemisphericalZOImodeling,thebreakorientationneedsto besimulatedatvariousanglesaroundthelooppipingtodeterminemaximum debrisgeneration(1).TheCASAGranderisk-informedmethoddfrom NEI04-07bysamplingrandombreakorientationovermanybreakscenarios withtrackedvarianceoverthetotalrisksolutiontoensurethatallcontributing combinationshavebeensampled.Thistypeofvariancetrackingensuresthatall distributions,includingbreakorientationandalluserentereddistributionshave beenproperlysampledovertheirfullranges.Ifthebreakinquestionoccurson thebottomofapipenearthe"oor,theboundaryoftheZOIisrepresentative ofalljetre"ectionsthatoccurfromthebreakjetimpingementontheconcrete "oor,asvisualizedinFigure4.

REFERENCES 1.NEI04-07Volume1.PressurizedWaterReactorSumpPerformanceEval-uationMethodology.Revision0:NuclearEnergyInstitute,December2004.2.NEI04-07Volume2.SafetyEvaluationbytheofNuclearReactorRegulationRelatedtoNRCGenericLetter2004-02,Revision0,December6, 2004.Revision0:NuclearEnergyInstitute,December2004.3.ANSI/ANS-58.2-1988.DesignBasisforProtectionofLightWaterNuclearPowerPlantsAgainsttheEofPostulatedPipeRupture.58.2-88:American NuclearSociety,October6,1988.Tuesday1 stMarch,2016:19:32,Page384of393 DRAFTPART4.RAIRESPONSES(ROUND2)Figure4:HemisphericalZOIexampleonbottomof31"pipe4.6.26Question62STPResponse:(Item62,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.27Question63STPResponse:(Item63,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Thede-brisdistributionisaccountedforinthebasisfortheplant-speci"cdeterministic

testing.4.6.28Question64STPResponse:(Item64,Page110)TheSTPriskmethodologyhasbeenrevisedtoapplyRoverD(seeAttach-ment7)insteadofusingCASAGrandetogenerateconditionalfailureprobabil-ities.RoverDisalesscomplexapproachthatrelegatesbreaksizesthatgenerate andtransportdebristhatisnotboundedbydeterministictestingtofailure.

RoverDdoesnotrelyonacorrelationormodeltoaccountforheadloss.Head lossisaccountedforintheplant-speci"cdeterministictesting.4.6.29Question65STPResponse:(Item65,Page111)TheRoverDmethodology(seeAttachment7)doesnotuseCASAGrandeTuesday1 stMarch,2016:19:32,Page385of393 DRAFTPART4.RAIRESPONSES(ROUND2)tocalculateconditionalprobabilitiesordeterminefailures.RoverDmethodologyassumesthatanybreakthatgeneratesmore"brousdebristhanwasrepresented inthetestinggoestofailure(coredamage).Thedeterministictestingiscredited withshowingthattherearenofailuresforconditionsboundedbythetested con"gurationanddebrisloading.Safetymarginisprovidedinthedeterministic sense.Itiscomprisedoftheconservatismoftheengineeringassumptionsand methodologyandtestedcon"guration(e.g.,chemicalfailedcoatings, etc.).TheresponsetotheSTSBRAIinAttachment6providessomeadditional informationonconservatismintheanalysisandtesting.4.6.30Question66STPResponse:(Item66,Page111)TheRoverDanalysisreliesontheUFSARhotlegswitchovertimeandtheRELAP5analysisisnotreliedon.TheRoverDanalysisalsoshowsthatvery little"berarrivesonthecore.Theamountsaresosmallthatitisunlikely mixing"owswillbeimpeded.ThereforeSTPNOChasconcludedthatadequate circulationwillbeavailabletodiluteboricacid.Insummary,STPNOCsevaluationshowsthatthesmallamountsof"berthatmayaccumulatewouldnotcorecoolingorBAP,suchthattheywould notclosingGL2004-02.STPNOCsanalysisissimilarinapproachand conclusionstohowtheNRCaddressedBAPintheSEtoWCAP16793-NP.4.7ML15091A440,STSBResponses4.7.1Question4STPResponse:(Item4,Page113)AsdiscussedinapublicmeetingwiththeNRConFebruary4,2015,STPNOCplanstoproposeachangetotheTSforECCSandforCSStoadda LCOandactionstatementspeci"ctodebrisTheoperabilityrequirement fortheLCOwillbebasedonthequantityofdebrisintheSTPdebrisanalysis andoperabilitydeterminationswillnotinvolveapplicationofprobabilisticrisk.Aspresentedinthemeeting,STPNOCisintheprocessofrevisingitsrisk-informedGSI-191pilotlicensingapplicationtoimplementamuchlesscomplexRiskoverDeterministic(RoverD)methodology.RoverDwillformthetechnicalbasisfortheproposedchangetotheTS.InRoverD,theeofdebristhatareboundedbytheplant-speci"ctestingaredeterministicallymitigatedinaccordancewithNRC-acceptedmethodology forresolutionofGL2004-02.ByapplyingpipebreakfrequenciesfromNUREG 1829,STPNOCshowsthattheriskassociatedwithdebrisfrompipebreaksthat generatequantitiesofdebristhatarenotboundedbyplant-speci"cprototypical testingisverysmall,inaccordancewiththeacceptancecriteriaofRG1.174.The breaklocationsthatcangeneratedebrisoutsidetheassumedtestconditionsare RCSbreaksinthepressurizersurgelineandRCSlooppiping.Defenseindepth andsafetymargininthetestingandcalculationassumptionsprovidereasonable assurancethatthesumpstrainerscanperformtheirsupportfunctionsforECCS andCSSevenforthedebrisgeneratedfromtheselargerbreaks.MoredetailwithTuesday1 stMarch,2016:19:32,Page386of393 DRAFTPART4.RAIRESPONSES(ROUND2)regardtoRoverDisprovidedinAttachment7.TheLCOforthechangetotheTSwillbebasedontheamountofdebrisintheSTPdebrisanalysis.ThedraftLCOpresentedintheFebruary4,2015, meetingread:ReactorContainmentBuildingemergencysumpshallbeOPERA-BLEbylimitingthecontainmentdebrisquantitiestobelessthanor equaltotheSTPdebrisanalysisassumptions.Theoperabilitydeterminationforapotentiallydegradedornonconformingconditionwouldinvolveevaluationofthequantity,natureandtransportability ofthedebrisinquestiontodetermineifitiswithintheSTPdebrisanalysis.It doesnotinvolveariskassessment.Thespeci"citemslistedintheRAIarediscussedbelow.ExceptfortheLOCAfrequencyassumptions,whichwillberemovedasafactorintheop-erabilitydetermination,theyareassumptionsthataretypicalinengineering analysesandwhichoftenhaveconservatismsthatcanbeusedformargininan operabilitydetermination.1.Generalassumptions2.Equipmentfailureassumptions(priortostartofrecirculation):Totheextentthattheseareusedtoestablishthequantityofdebrisassumedin theplant-speci"ctesting,theycouldbeusedtoidentifymargin.3.LOCAfrequencyassumptions:Thiswouldnotbeappliedintheoperabilitydeterminationandwillberemovedfromthelist.4.Debrisgenerationassumptions:Thereareassumptionsinthemodelingforhowmuchdebrisisgeneratedatvariouslocationswhicharerelated tophysicalconditionssuchascreditforpresenceofphysicalbarriersto breakeThesearenotrelatedtotheriskandcouldpossiblybere-visedtoreducetheamountofdebrisassumedtobegeneratedandprovide additionalmargin.5.Chemicalassumptions:Theseassumptionsarenotrelatedtotheriskevaluation.Theplant-speci"ctestingusedWCAP-16530todetermine thedebrisquantitiesforthetest.OtherSTPtestinghasshownthatSTP hasverylittlechemicalWithlessassumedchemicalonhead loss,thestrainerscanhandlemoredebris.Thereissigni"cantmarginthat canbeappliedinanoperabilitydetermination.6.Debristransportassumptions:Theseassumptionswouldgenerallybeap-pliedtodetermineifanidenti"edconditioninvolvesdebristhatistrans-portable.Ifitisnottransportable,thenitgenerallyshouldnotbeof concern.Theremaybesomeconservatismthatcanbeappliedonacase-by-casebasis.ThereisnoPRA/riskelementforthistypeofevaluation.Tuesday1 stMarch,2016:19:32,Page387of393 DRAFTPART4.RAIRESPONSES(ROUND2)7.Headlossassumptions:ThedebrisheadlossusedforNPSHisbasedontestresults.ConservativeassumptionsfortheNPSHdeterminationinclude maximumsumptemperature,minimumsumpwaterlevel,maximumpump "owrates,andconservativecalculationofthecleanstrainerheadloss.8.Degasi"cationassumptions:Vortexing,airingestion,andvoidfractionareaddressedseparatelyasitsownissue.Asshownbytesting,thePCIde-signedstrainersarenotsubjecttovortexingissuesevenwithaverylow submergence.Vortexbreakersareinstalledinthesumppit.Voidfractionis notaconcernbasedonconventionalhydraulicand"uid"owcalculations.9.Penetrationassumptions:Fiberpenetrationisameasuredvalueandmea-surementuncertaintiesareincludedintheevaluation.ThereisnoPRA/risk elementassociatedwiththisparameter.10.Coreblockageassumptions:Theevaluationassumesthecoreandbypass"owisfullyblockedforallsmallbreaksandallhotlegbreaks.Itisassumed

that<15g/FuelAssemblywillprovideadequatecoolingformediumandlargecoldlegbreaks.Thisisaconservativeassumptionthatcouldbe reviewedformargininanoperabilitydetermination.11.Acceptancecriteriaassumptions:Allofthefactorsabovegenerallyfeedintoacceptancecriteria.Tuesday1 stMarch,2016:19:32,Page388of393 DRAFTBibliographyAlionScience&Technology(2008).GSI-191ContainmentRecirculationSumpEvaluation:DebrisGeneration.ALION-CAL-STPEGS2916-002,Revision 3,(Reference5toSTPSTI33647079),AlionScience&Technology,Albu-querque,NM.AlionScience&Technology(2009).InsulationDebrisSizeDistributionforUseinGSI-191Resolution.ALION-REP-ALION2806-01,Revision4, ML15091A440,AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2011).ErosionTestingofSmallPiecesofLowDen-sityFiberglassDebris-TestReport.ALION-REP-ALION1006-04,Revision 1,ML14202A045,AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2014).Risk-InformedGSI-191DebrisTrans-portCalculation.ALION-CAL-STP8511-08,Revision3,(Referencein ML15091A440),AlionScience&Technology,Albuquerque,NM.AlionScience&Technology(2015a,April).CASAGrandeTheoryManual.ALION-SPPALION-I009-10,STPSTI34179370,AlionScience&Technol-ogy,Albuquerque,NM.AlionScience&Technology(2015b,July).FinalCASAGrande,RoverDandDEGB,FiberFineandIOZDebrisGenerationQuantitiesandDocumenta-tion.LTRMAS-2K15-07-21R0,STPSTI34164251,AlionScience&Tech-nology,Albuquerque,NM.AREVA(2008,August).SouthTexasProjectTestReportforECCSStrainerTesting.AREVANPDocument66-9088089-000,AREVANP,7207IBM Drive,Charlotte,NC28262.Arrow,K.J.(1951).SocialChoiceandIndividualValues.Wiley,NewYork.Budnitz,R.J.,G.Apostolakis,D.M.Boore,L.S.K.J.Coppersmith,C.A.Cornell,andP.A.Morris(1998).Useoftechnicalexpertpanels:Ap-plicationstoprobabilisticseismichazardanalysis.RiskAnalysis18,463-469.Clement,R.T.andR.L.Winkler(1999).Combiningprobabilitydistributionsfromexpertsinriskanalysis.RiskAnalysis19,187-203.Cooke,R.M.(1991).ExpertsinUncertainty:OpinionandSubjectiveProbabilityinScience.OxfordUniversityPress,NewYork.

389 DRAFT BIBLIOGRAPHYCrenshaw,J.W.(2012,January).SouthTexasProjectUnits1and2DocketNos.STN50-499,SummaryoftheSouthTexasProjectRisk-InformedApproach toResolveGenericSafetyIssue(GSI-191).LetterfromJohnW.Crenshawto USNRC.EPRI(1999).RevisedRisk-InformedIn-ServiceInspectionProcedure.TR112657RevisionB-A,ElectricPowerResearchInstitute,PaloAlto,CA.Fleming,K.N.,B.O.Lydell,andD.Chrun(2011,July).DevelopmentofLOCAInitiatingEventFrequenciesforSouthTexasProjectGSI-191.TechnicalRe-port,KnFConsultingServices,LLC,Spokane,WA.French,S.(1985).Groupconsensusprobabilitydistributions:Acriticalsurvey.

InBayesianStatistics2,pp.183-197.North-Holland,Amsterdam.Genest,C.andJ.V.Zidek(1986).Combiningprobabilitydistributions:Acritiqueandannotatedbibliography.StatisticalScience1,114-148.Hasenbein,J.(2015,May).OrderRelationsforConcaveInterpolationMethods.TechnicalReport2015-001,TheUniversityofTexasatAustin,Austin,TX.Hindmarsh,A.C.(1983).ODEPACK,ASystematizedCollectionofODESolvers.Volume1ofComputing.R.S.Steplemanetal.(eds.).North-Holland,Amsterdam(1983):,pp.55-64.North-Holland,Amsterdam(1983).Hochreiter,L.E.(2005,December).Datacollectionofpipefailuresoccuringinstainlesssteelandcarbonsteelpiping.NucE597D-Project1,Pennsylvania StateUniversity.INEL(2007).Industry-AveragePerformanceforComponentsandInitiatingEventsatU.S.CommercialNuclearPowerPlants.NUREGCR-6928,Idaho NationalEngineeringLaboratory,IdahoFalls,ID.INL(1995,August).RELAP5/MOD3CodeManual.INEL95/0174,IdahoNationalLaboratory,IdahoFalls,ID.INL(2012,June).RELAP5-3DCodeManual.INEEL-EXT98-00834,IdahoNationalEngineeringLaboratory,IdahoFalls,ID.Johnson,D.(2015,June).PRACalculationsinSupportofRoverDWhitePaperDevelopment.LetterReportSTP-338116-O-02,STPSTI34176256,ABSG ConsultingInc.,Irvine,CA92602.Johnson,N.(1949).SystemsofFrequencyCurvesGeneratedbyMethodsofTranslations.Biometrika36,149-176.Letellier,B.(2011).Risk-InformedResolutionofGSI-191atSouthTexasProject.TechnicalReportRevision0,SouthTexasProject,Wadsworth,TX.Mans"eld,C.(2004).PeerReviewofExpertElicitation.MemoPreparedfortheEnvironmentalProtectionAgency,RTIInternational.Tuesday1 stMarch,2016:19:32,Page390of393 DRAFT BIBLIOGRAPHYMeyer,M.A.andJ.M.Booker(1990).ElicitingandAnalyzingExpertJudg-ment:APracticalGuide,NUREG/CR-5424,U.S.NuclearRegulatoryCom-

mission.Mosleh,A.(2011,October).TechnicalReviewofSTPLOCAFrequencyEstima-tionMethodology.LetterReportRevision0,UniversityofMaryland,College Park,MA.NEI(2004,May).PressurizedWaterReactorSumpPerformanceEvaluationMethodology.TechnicalReport04-07,NuclearEnergyInstitute,1776IStreet, Washington,DC.NRC(2011).RegulatoryGuide1.174:AnApproachforUsingProbabilisticRiskAssessmentInRisk-InformedDecisionsOnPlant-Speci"cChangesto theLicensingBasis,Revision2,NuclearRegulatoryCommission,Washington, DC.NRC(2012a,undated).FINALSAFETYEVALUATIONBYTHEOFFICEOFNUCLEARREACTORREGULATIONTOPICALREPORTWCAP-16793-NP,REVISION2EVALUATIONOFLONG-TERMCOOLINGCON-SIDERINGPARTICULATE,FIBROUSANDCHEMICALDEBRISINTHE RECIRCULATINGFLUID,PRESSURIZEDWATERREACTOROWNERS GROUPPROJECTNO.694.NRCSafetyEvaluation.NRC(2012b,August).GSI-191:Thermal-HydraulicResponseofPWRRe-actorCoolantSystemandContainmentstoSelectedAccidentSequenc.

NUREG/CR6770,LA-UR-015561,NuclearRegulatoryCommission,Wash-ington,DC.Ogden,N.,D.Morton,andJ.Tejada(2013,June).SouthTexasProjectRisk-InformedGSI-191Evaluation:FiltrationasaFunctionofDebrisMassonthe Strainer:FittingaParametricPhysics-BasedModel.Technicalreport,STP-RIGSI191-V03.06,TheUniversityofTexasatAustin,Austin,TX.Pan,Y.,E.Popova,andD.Morton(2013,January).ModelingandSamplingLOCAFrequencyandBreakSize.Stp-rigsi191-v03.02,TheUniversityof TexasatAustin,Austin,TX.Powell,G.T.(2013,November13).Supplement1toRevisedSTPPilotSubmit-talforaRisk-InformedApproachtoResolvingGenericSafetyIssue(GSI)-191 toSupersedeandReplacetheRevisedPilotSubmittal.ML13323A183,Letter fromGeraldT.PowelltotheUSNRCDocumentControlDesk;STPLetter

NOC-AE-13003043.Powell,G.T.(2015a,March25).DescriptionofRevisedRisk-InformedMethod-ologyandResponsestoRound2RequestsforAdditionalInformationRe-gardingSTPRisk-InformedGSI-191LicensingApplication.ML15091A440, LetterfromGeraldT.PowelltotheUSNRCDocumentControlDesk,NOC-

AE-15003220.Tuesday1 stMarch,2016:19:32,Page391of393 DRAFT BIBLIOGRAPHYPowell,G.T.(2015b,January).ResponsetoRequestforAdditionalInformationreUseofRELAP5inAnalysesforRisk-InformedGSI-191LicensingApplica-tion.ML14009A307,LetterfromGeraldT.PowelltotheUSNRCDocument ControlDesk.PWROG(2011,October).EvaluationofLong-TermCoolingConsideringParticulate,FibrousandChemicalDebrisintheRecirculatingFluid.WCAP 16793,Revision2,PressurizedWaterReactorOwnersGroup,Pittsburgh,PA.Rao,D.,C.andE.Haskin(1998,February).DrywellDebrisTransportStudy.NUREG/CR6369,USNRC,Washington,DC.STPNOC(2015,February4).STPRisk-InformedApproachtoGSI-191.ML15034A114,NRCpublicmeetingslides.TexasA&M(2013a,January).CoreBlockageThermal-HydraulicAnalysis.Cal-culationreportRevision2.1,STPSTI33719219,TexasA&MUniversity,Col-legeStation,Texas.TexasA&M(2013b,July).SouthTexasProjectPowerPlantRETRAN-RELAP5-3DConversionTables.CalculationreportRevision1.0, ML14029A533,TexasA&MUniversity,CollegeStation,Texas.TexasA&M(2013c,August).STPPowerPlantRELAP5-3DSteady-StateFi-nalConditions.CalculationreportRevision1.0,ML14029A533,TexasA&M University,CollegeStation,Texas.TexasA&M(2013d,July).STPPowerPlantRELAP5-3DSteady-StateModelVeri"cation.CalculationreportRevision1.0,ML14029A533,TexasA&M University,CollegeStation,Texas.Tregoning,R.,L.Abramson,andP.Scott(2008,April).EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElicitationProcess.NUREG/CR1829,NuclearRegulatoryCommission,Washngton,DC.Tregoning,R.,P.Scott,andA.Csontos(2008,April).EstimatingLoss-of-CoolantAccident(LOCA)FrequenciesThroughtheElicitationProcess:Main Report(NUREG-1829).NUREG1829,NRC,Washington,DC.Uhle,J.L.(2005,December).Nrccommentsonpennsylvaniastateuniversitystudyofpipefailuredata.ML053410452,NRC,Washington,D.C.Vaghetto,R.andY.A.Hassan(2013).Studyofdebris-generatedcoreblock-agescenariosduringlossofcoolantaccidentsusingRELAP5-3D.NuclearEngineeringandDesign261(0),144-155.VonWinterfeldt,D.andW.Edwards(1986).DecisionAnalysisandBehavioralResearch.CambridgeUniversityPress,NewYork,NY.Tuesday1 stMarch,2016:19:32,Page392of393 DRAFT BIBLIOGRAPHYWake"eld,D.andD.Johnson(2013,January).SouthTexasProjectRisk-InformedGSI-191Evaluation,Volume2,ProbabilisticRiskAnalysis:De-terminationofChangeinCoreDamageFrequencyandLargeEarlyRelease FrequencyDuetoGSI-191Issues.Technicalreport,STP-RIGSI191-VO2, Revision0,ABSGConsultingInc.Westinghouse(2011,April).TheNuclearDesignandCoreManagementoftheSouthTexasProjectUnit1NuclearPowerPlantCycle17.WCAP17399-P, WestinghouseElectricCompany,Pittsburgh,PA.Zolan,A.,J.Hasenbein,andJ.Tejada(2015a,June).FiberOperationsEngine.TechnicalReport2015-002,STPSTI34164169,TheUniversityof TexasatAustin,Austin,TX.Zolan,A.,J.Hasenbein,andJ.Tejada(2015b,July).RiskUnifyingFrequencyFunctional.TechnicalReport2015-003,STPSTI34164176,TheUniversity ofTexasatAustin,Austin,TX.Tuesday1 stMarch,2016:19:32,Page393of393