ML11192A002
| ML11192A002 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 07/08/2011 |
| From: | Feintuch K Division of Operating Reactor Licensing |
| To: | Browning T Florida Power & Light Co |
| References | |
| Download: ML11192A002 (11) | |
Text
NRR-PMDAPEm Resource From: Feintuch, Karl Sent: Friday, July 08, 2011 2:46 PM To: Browning, Tony Cc: Harrison, Donnie; ONeal, Daniel; Howe, Andrew; Chawla, Mahesh
Subject:
FW: Additional RAI items for the DAEC TSTF-425 adoption amendment application Attachments: ME5744 RAI resp (20Apr11), ML1111105070.pdf Repeat copy of this message is sent for the benefit of Ccd personnel.
From: Feintuch, Karl Sent: Friday, July 08, 2011 2:44 PM To: 'Browning, Tony'
Subject:
Additional RAI items for the DAEC TSTF-425 adoption amendment application These items were sent to me by the APLA Branch Chief as a result of the July 7, 2011, call discussing the PRA Model status relative to ME5744, TSTF-425 adoption. The items are separately identified to facilitate any further specific discussion.
I am sending them as draft RAI items. For traceability, I linked them to the July 7, 2011, discussion (that is RAI 2011-07-07 prefix). If you have another more suitable identifier scheme, then just apply it and precede each answer with the associated item text.
Please confirm that your responses can be absorbed within the existing August 15, 2011, response schedule.
Karl Feintuch USNRC 301-415-3079
========= begin RAI 2011-07-07 items ========
Please confirm, or clarify, the following summary of the July 7, 2011 conference call. Based on this conference call, the staff understands that:
- 1. The probabilistic risk assessment (PRA) model, Revision 6, proposed for the TSTF-425 application, is complete.
- 2. The status of the open gap items for Revision 6 is as provided in the supplemental information, dated April 20, 2011.
- 3. The focused peer review, noted in the supplemental information, utilized appropriate independent peer reviewers consistent with Regulatory Guide 1.200.
- 4. The focused peer review reviewed the 83 potential gap items from the 2007 full scope peer review, including the 30 provided in the February 23, 2011 submittal.
- 5. The focused peer review also reviewed new methods and PRA model changes associated with the upgrade to Revision 6.
- 6. This focused peer review identified 12 items, 5 of which have been incorporated into Revision 6, and 7 open items as provided in the supplemental information.
- 7. The 7 open gap items supersedes the 30 open gap items provided in TSTF-425 application submittal, dated February 23, 2011, for Revision 6.
1
- 8. The 12 items include gap items not previously identified in the February 23, 2011 submittal.
- 9. In addition to confirming, or clarifying this summary, please describe the 5 gap items noted in the supplemental information and, for each with its own unique identifier, how they were dispositioned via the Revision 6 PRA model.
Duane Arnolds RAI response of April 20, 2011 (ADAMS Accession No. ML111110507), attached for convenience, is also the basis of our current understanding.
======== end RAI 2011-07-07 items ===
2
Hearing Identifier: NRR_PMDA Email Number: 99 Mail Envelope Properties (Karl.Feintuch@nrc.gov20110708144600)
Subject:
FW: Additional RAI items for the DAEC TSTF-425 adoption amendment application Sent Date: 7/8/2011 2:46:21 PM Received Date: 7/8/2011 2:46:00 PM From: Feintuch, Karl Created By: Karl.Feintuch@nrc.gov Recipients:
"Harrison, Donnie" <Donnie.Harrison@nrc.gov>
Tracking Status: None "ONeal, Daniel" <Daniel.ONeal@nrc.gov>
Tracking Status: None "Howe, Andrew" <Andrew.Howe@nrc.gov>
Tracking Status: None "Chawla, Mahesh" <Mahesh.Chawla@nrc.gov>
Tracking Status: None "Browning, Tony" <Tony.Browning@fpl.com>
Tracking Status: None Post Office:
Files Size Date & Time MESSAGE 2786 7/8/2011 2:46:00 PM ME5744 RAI resp (20Apr11), ML1111105070.pdf 661615 Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:
Recipients Received:
Attachment to NG-11-0135 Page 1 of 6 Request for Clarifying Information - NextEra Energy Duane Arnold Probabilistic Risk Assessment Model for Use in Implementing TSTF-425, Rev.1 During a teleconference held on March 29, 2011 between the NRC Staff and NextEra Energy Duane Arnold personnel, the Staff requested that information contained in of the referenced application (Documentation of PRA Technical Adequacy) be clarified to assist the Staff in evaluating the Duane Arnold Energy Center (DAEC)
Probabilistic Risk Assessment (PRA) model. Specifically, the following information was requested:
- 1) The application states that Revision 6 of the DAEC PRA, currently under development, will be the model used to implement this Technical Specification (TS) change upon approval. When is it expected to be finalized and issued for use?
Response
As stated in the application, Revision 6 is intended to also support the conversion of the DAEC Fire Plan to the NFPA-805 standard. As the license amendment request for the Fire Plan conversion is currently scheduled for submission by June 29, 2011, Revision 6 of the DAEC PRA will be implemented no later than that date.
- 2) The application discusses the results of the Peer Review conducted on the DAEC PRA model, Revision 5C. That review resulted in the identification of 83 potential gaps to meeting Capability Category II in the Supporting Requirements of the ASME Standard. However, the Tables provided in Attachment 2 of the submittal only discuss 30 of those items. Please provide a discussion of the disposition of all 83 identified items and the expected status of any open items when Revision 6 of the model is issued.
Response
The intent of the Attachment 2 Tables was to discuss only those items that remained in an open status at the time of the application and to bin them into separate Tables by significance. Therefore, any item which had already been dispositioned and closed in the Revision 6 model was not reported in the Tables because they no longer represented gaps to Capability Category II. Because Peer Reviews often result in findings that may represent potential gaps in more than one Supporting Requirement in the ASME Standard, there was overlap between the line items found in the 3 Tables in the application which makes a simple tallying of them back to the original 83 items difficult.
Subsequent to the original application, NextEra Energy performed a follow-up Focused Peer Review to validate the closure of those previously identified 83 items from the 2007 Peer Review. In addition, that review utilized the current version of the ASME Standard (RA-Sb-2009).
Attachment to NG-11-0135 Page 2 of 6 The Focused Peer Review team found that NextEra Energy had appropriately incorporated most of the 83 previously identified items into Revision 6. However, not all of the closures were found to fully meet Capability Category II requirements, which resulted in new open items, in addition to those items that remained open at the time of the Focused Peer Review. The final result was a total of 12 items that were assessed as not meeting Capability Category II per the current ASME Standard. Of these 12 items, five will be addressed and incorporated into Revision 6 of the DAEC model upon issuance prior to June 29, 2011. The remaining seven items are judged to have either no, or only minor, impact on the models ability to support this application. The following Table describes those seven open items.
In order to not repeat the confusion created by binning them into gaps, findings, and suggestions, as was done in the original Attachment 2 Tables, we have simplified the presentation of the current open items on the pending Revision 6 of the DAEC PRA model into a single Table.
Attachment to NG-11-0135 Page 3 of 6 ASMECategoryIISRsNotMetinDAECModel,Rev.6
ASMESRs CategoryIISRDetails DescriptionofGAP ImpactonQuantification ImportancetoApplication
GROUPinitiatingeventsonlywhenthe SeveralfindingsandsuggestionsunderHLRAandHLRBhavebeen
followingcanbeassured: dispositioned/resolved,butthesubsuming(IEB3)andscreening
(IEC4(C6))ofinitiatingeventsdoesnotmeetthestandard.The
(a) eventscanbeconsideredsimilarin followingprovidesexamplesummarizes(IENotebook,including
termsofplantresponse,success AppendixH):
criteria,timing,andtheeffectonthe
operabilityandperformanceof x RBCCW(failsCRD,whichiscreditedforearlyinjection)is
operatorsandrelevantmitigating subsumedbyTT,butRBCCWisnotfailedgivenTT.
systems;or Modelingtheseadditionalinitiatorswill
x GSW(failsRBCCW,CRD,Feedwater,etc.)issubsumedbyTC,but
betterdefinecertainaccidentsequences Althoughtheimportanceofaffected
thesesystemsarenotfailedgivenTC.
andamoreaccuratelydetermine componentsisnotfullyconsidered;
(b) eventscanbesubsumedintoagroup x TheimpactsofReferenceandVariableLegBreaksarenot
associatedSSCimportance. theirimpactcanbeaddressedfor
andboundedbytheworstcaseimpacts adequatelydescribedandaresubsumedbyLossofFW.Most
specific5bapplicationsusing
IEB301A withinthe"new"group. likelywouldbeamanualshutdownwithcomplicationsversesa
Overallcalculatedriskslightlyincrease; sensitivityanalysis,qualitative
LossofFW.Giventhatimmediateshutdownwouldoccurgivena
significantlyforspecificfunctions analysis,boundinganalysisor
AVOIDsubsumingeventsintoagroup break,theseshouldbemodeled.Section2.4.8describedthelow
associatedwiththeinitiatingevent.Some explicitmodelinginaccordancewith
unless: riskfromthese,butthisdoesnotmeetstandardforscreening.
applicationsmayseeaslightdecreasein theNEI0410guidance.
x 1A1/1A2busfailuresandpartiallossoffeedwater(onepump)are
(i) theimpactsarecomparabletoorless binnedtoTT,butthisimpactisnotmodeledgivenTT. riskmargin.
thanthoseoftheremainingeventsin x 1A3/1A4busfailuresaresubsumedwithTT.Impactonlossof
thatgroup, chargers[TS3.8.4.]etc.andpossibilitythatfailureisaproblem
couldleadtoanimmediateshutdown.Notes11and12suggest
AND thatonlynormalpowersourceislost,butemergencypoweris
alsounavailableifbusfails.
(ii) itisdemonstratedthatsuchgrouping
doesnotimpactsignificantaccident RECOMMENDATION:FollowIEB3andC6withregardtosubsuming
sequences. andscreeningormoreimportantlymodeltheaboveinitiatingevents.
TheSBOeventtreedoesnottakecreditforcontainmentventing CreditingtheB5bprocedurethat Willimproveresultsfor5b
usinganalternatealignmentwhenthepneumaticsupplyislost.DAEC implementscontainmentventingwithouta applicationsespeciallythose
procedureSAMP706providesdetaileddirectionforventingPCgiven pneumaticsupplywillreduceoverall functionsassociatedwithSBO.
INCLUDEtheeffectsofbothnormaland anunavailablepneumaticsupply.TheContainmentVentnotebook calculatedrisk.Willhaveamoresignificant
SYA501A alternatesystemalignments,totheextent doesnotcredit/discussthisprocedure. impactonSBOsequences.
Withoutthischangethemodelis
neededforCDFandLERFdetermination.
conservative.
RECOMMENDATION:Addcontainmentventingtotheeventtree
alongwithoperatoractionsandcomponentalignmentsneededto
ventcontainmentwithoutthepneumaticsupplysystem.
Attachment to NG-11-0135 Page 4 of 6 ASMECategoryIISRsNotMetinDAECModel,Rev.6
ASMESRs CategoryIISRDetails DescriptionofGAP ImpactonQuantification ImportancetoApplication
ThereisnoFireWaterSystem(AlternateInjection)notebookor Documentingtheuseofthefirewater Willimproveresultsfor5b
DOCUMENTthesystemfunctionsand equivalentinformationinanothernotebook.Theoperatoractionto systemasanalternateinjectionsourcewill applicationsespeciallythose
boundary,theassociatedsuccesscriteria, alignfirewaterforinjectionismodeledbutthecomponentsare facilitateamorethoroughevaluationof functionsassociatedwithSBO.
themodeledcomponentsandfailure basedontheargumentthattheprobabilityoftheactionsubsumes thisfunction.Creditingfirewaterinjection
modesincludinghumanactions,anda thecomponentfailurerates.
SYC201A (lateintheevent)willdecreaseoverallrisk, Withoutthischangethemodelis
descriptionofmodeleddependencies
especiallyforSBOsequences. conservative.
includingsupportsystemandcommon
RECOMMENDATION:Developnewsystemnotebookforuseoffire
causefailures,includingtheinputs,
waterasanalternateinjectionsource.
methods,andresults.
HRANotebook(AppendixJ,TableJ1)includesasystematicapproach Noimpact.Asnotedbythereviewteama NoimpactsinceDAECstaffdid
toidentifyingtestandmaintenanceactivitiesthroughasystemby systematicapproachwasusedtoidentify reviewallprocedures;howeverthey
systemreviewofpotentialmisalignments.Thismeetsthehighlevel potentiallysignificantmisalignments. didnotdocumentthisreview.
requirementtouseasystematicapproachandisjudgedtobe Basedonthisreview,onlytheprocedures
ForequipmentmodeledinthePRA, adequatebythePeerReviewteam.However,theSRwording thatwereassociatedwiththesealignments
IDENTIFY,throughareviewofprocedures requiresareviewofproceduresandpracticeswhichwasnot werereviewedfurther.DAECnotedthat
andpractices,thosetestandmaintenance followed.Asaresult,thePRteammustassessthisSRasnotmet. theydidreviewalltheproceduresbutdid
HRA101A
activitiesthatrequirerealignmentof notdocumentthisreview.
equipmentoutsideitsnormaloperational RECOMMENDATION:ReassessthisSRwhentheAddendumBofthe
orstandbystatus. PRAStandardisreleased.Thecurrentproposedrevisiondeletesthe
requirementforareviewofproceduresandpractices. ThedraftrevisionofaddendumBtoHRA1
thatiscurrentlyinreviewdeletesthe
requirementforareviewofprocedures
andpractices.
HRANotebook(AppendixJ,TableJ1)includesasystematicapproach Noimpact.Asnotedbythereviewteama NoimpactsinceDAECstaffdid
toidentifyingcalibrationactivitiesthroughasystembysystemreview systematicapproachwasusedtoidentify reviewallprocedures;howeverthey
ofpotentialmiscalibrations.Thismeetsthehighlevelrequirementto potentiallysignificantmiscalibrations. didnotdocumentthisreview.
useasystematicapproachandisjudgedtobeadequatebythePeer Basedonthisreview,onlytheprocedures
Reviewteam.However,theSRwordingrequiresthroughareviewof associatedwiththeseacionswerereviewed
IDENTIFY,throughareviewofprocedures proceduresandpracticeswhichwasnotfollowed.Asaresult,thePR further.DAECnotedthattheydidreview
andpractices,thosecalibrationactivities teammustassessthisSRasnotmet. alltheproceduresbutdidnotdocument
HRA201A thatifperformedincorrectlycanhavean
thisreview.
adverseimpactontheautomaticinitiation
RECOMMENDATION:ReassessthisSRwhentheAddendumBofthe
ofstandbysafetyequipment.
PRAStandardisreleased.Thecurrentproposedrevisiondeletesthe
requirementforareviewofproceduresandpractices. ThedraftrevisionofaddendumBtoHRA1
thatiscurrentlyinreviewdeletesthe
requirementforareviewofprocedures
andpractices.
Attachment to NG-11-0135 Page 5 of 6 ASMECategoryIISRsNotMetinDAECModel,Rev.6
ASMESRs CategoryIISRDetails DescriptionofGAP ImpactonQuantification ImportancetoApplication
AnumberofpreIEHFEsareidentifiedformodelinginthePRA. Roughly10preinitiatorsareaffected.The Mayhaveaminorimpactonsome
GenerallytheseHFEsareatthetrainorsystemlevel,asappropriate. probabilityforthesepreinitiatorsislow. 5bapplications.
However,asmallsetwereidentifiedatthesystemlevelwithout Thereforeaddressingthisfindingis
relatedtrainlevelHFEs.ItispossiblethatthetrainlevelHFEmaybe expectedtohaveaminorimpactonoverall
importanttosystemunavailability.Forexample,miscalibrationofDG risk.
Foreachunscreenedactivity,DEFINEa fueloilleveltransmittersisdoneatthesystemlevel,butnotatthe
humanfailureevent(HFE)thatrepresents trainlevel.Atthetrainlevel,theHFEwouldbe8e3,comparedwith
HRC101A theimpactofthehumanfailureatthe independentfailureoftheleveltransmitterof5e4.Inothercases,
appropriatelevel,i.e.,function,system, theHFEisatthetrainlevel,butnocorrespondingsystemlevel
train,orcomponentaffected. dependentHFEisincluded.Forexample,failuretorestoreRHRSW
postTMisdevelopedatthetrainlevel,butnocommonmisalignment
ofbothtrainsisconsidered.
RECOMMENDATION:Reviewthedifferencesbetweenthemodeling
ofsystemimpactvstrain.
CategoryIwasmet.Addinginitiatingevent Althoughtheimportanceofaffected
IDENTIFYsignificantcontributorstoCDF, RECOMMENDATION:Faulttreesarerequiredforsupportsystem faulttreeswillnotalteroverallresultsifthe SSCsonaninitiatingeventmaynot
suchasinitiatingevents,accident initiatingeventsinordertosatisfythisSR[CatII]. faulttreeresultsareinagreementwiththe befullyconsidered;theirimpactcan
sequences,equipmentfailures,common originalpointestimates.Howeverthere beaddressedforspecific5b
QUD5a01A causefailures,andoperatorerrors[CatI]. willbeanincreaseinriskimportance applicationsusingsensitivity
INCLUDESSCsandoperatoractionsthat associatedwithoperatoractionsandSSCs analysis,qualitativeanalysis,
contributetoinitiatingeventfrequencies thatareincludedintheinitiatingevent boundinganalysisorexplicit
andeventmitigation[CatII]. faulttrees. modelinginaccordancewiththeNEI
0410guidance.
Attachment to NG-11-0135 Page 6 of 6 These open items are contained in a controlled database that, by NextEra Energy procedure, must be reviewed prior to beginning any PRA application. Therefore, each open item will be reviewed as part of the Surveillance Test Interval change assessment.
If an open item has a potential impact on the results, then additional assessments (sensitivities) will be performed in accordance with the guidance contained in NEI 04-10.
In summary, with the exception of the seven items listed in the above Table, all previously identified items that represent gaps to Capability Category II will be fully incorporated into Revision 6 of the DAEC PRA model upon formal issuance.