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{{Adams
#REDIRECT [[NOC-AE-16003412, Revised Response to Request for Additional Information APLA-4-4 STP Risk-Informed GSI-191 Licensing Application]]
| number = ML16272A162
| issue date = 09/12/2016
| title = South Texas Project, Units 1 and 2 - Revised Response to Request for Additional Information APLA-4-4 STP Risk-Informed GSI-191 Licensing Application
| author name = Connolly J
| author affiliation = South Texas Project Nuclear Operating Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000498, 05000499
| license number =
| contact person =
| case reference number = NOC-AE-16003412, TAC MF2400, TAC MF2401
| document type = Letter, Response to Request for Additional Information (RAI)
| page count = 7
| project = TAC:MF2400, TAC:MF2401
| stage = Response to RAI
}}
 
=Text=
{{#Wiki_filter:South Texas Project Electr;c Generating Station P.O Bax 28.9 W1dswortli. Texas 77483 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555-0001 South Texas Project Units 1and2 Docket Nos. STN 50-498, STN 50-499 September 12, 2016 NOC-AE-16003412 10 CFR 50.12 10 CFR 50.90 Revised Response to Request for Additional Information APLA-4-4 Regarding STP Risk-Informed GSl-191 Licensing Application (TAC Nos Mf 2400 and Mf 2401)
 
==References:==
: 1. Letter; G. T. Control Desk; "Supplement 2 to STP Pilot Submittal and Requests for Exemptions and License Amendment for a Risk-Informed Approach to Address Generic Safety Issue (GSl)-191 and Respond to Generic Letter (GL) 2004-02"; August 20, 2015; (NOC-AE-15003241) (ML 15246A126). 2. L. Regner_to D. '.'Sol._!th Texas Project, Units 1 and 2-Request for Additional Information Related fo the Risk R_eview of the Request for Exemptions and License Amendments to Resolve the Issue of Potential Debris Blockage on Emergency Recirculation During Design-Basis Accidents at Pressurized-Water Reactors"; May 26, 2016; (ML 16125A290). -3. Letter; G. T. Powell to USNRC Document Control Desk; "Responses to APl,.A Round 4 Requests for Additional Information Regarding STP Risk-Informed GSl-191 Licensing Application"; July 21, 2016; (NOC-AE-16003390) (ML 16230A232). Reference 3 provided STP Nuclear Operating Company's (STPNOC's) responses to the NRC staff's APLA round 4 requests for additional information (RAls) transmitted in Reference 2 regarding the STPNOC Risk-Informed GSl-191 application in Reference 1. A revised response _ to APLA-4-4 is provided in the Enclosure to this letter. There are no commitments in this letter. STI: 34368320 NOC-AE-16003412 Page 2 of 3 If there are any questions or if additional information is needed, please contact Drew Richards at (361) 972-7666 or me at (361) 972-7344. I declare under penalty of perjury that the foregoing is true and correct. Executed on amr/JWC James Connolly Site Vice President
 
==Enclosure:==
Revised Response to Request for Additional Information APLA-4-4 cc: (paper copy) Regional Administrator, Region IV U.S. Nuclear Regulatory Commission 1600 East Lamar Boulevard Arlington, TX 76011-4511 Lisa M. Regner Senior Project Manager U.S. Nuclear Regulatory Commission One White Flint North (08H04) 11555 Rockville Pike Rockville, MD 20852 NRC Resident Inspector U.S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN116 Wadsworth, TX 77483 (electronic copy) NOC-AE-16003412 Page 3 of 3 Morgan. Lewis & Bockius LLP Steve Frantz, Esquire U.S. Nuclear Regulatory Commission Lisa M. Regner NRG South Texas LP Chris O'Hara Jim van Suskil Skip Zahn CPS Energy Kevin Pollo Cris Eugster L. D. Blaylock City of Austin Elaina Ball John Wester Texas Dept. of State Health Services Helen Watkins Robert Free ENCLOSURE Enclosure NOC-AE-16003412 Page 1of4 Revised Response to Request for Additional Information APLA-4-4 Enclosure NOC-AE-16003412 Page 2 of 4 APLA-4-4 Please provide values of total risk estimates (also including water hammer and seismically induced LOCA) for the plant expressed as core damage frequency (CDF) and large early release frequency (LERF). Those values are not available in the recent Rovero analysis (Reference 2). This information is needed to compare pairs {CDF, and {LERF, to risk acceptance guidelines in RG 1.17 4. STPNOC Response STPNOC provided the following response to this RAI in NOC-AE-16003390 (ML 16230A232): Water hammer events are screened from consideration due to system and component design as described previously in the response to APLA-4-3. Therefore, water hammer is assessed to result negligible increase in risk. Seismically-induced LOCA risk estimates are provided in the response to RAI APLA-4-2, above. CDF and LERF from seismically-induced LOCA are found to be insignificant to the assessment. STPNOC is revising the response to this RAI by adding the following information: The STP PRA is a full-scope, at-power, integrated Level 1 and Level 2 PRA that applies to both STP Unit 1 and Unit 2. STP's PRA includes internal and external events as well as features such as a seismic PRA, a fire PRA (including spatial interactions analysis), human reliability analysis, and detailed common cause modeling. The Level 1 and Level 2 results for the current PRA model of record (STP _REV81) are presented in the table below. Initiating Events CDF %CDF LERF External Events HWIND Tornado Induced Failure of Switchyard and ECP 1.08E-06 13.72 1.16E-07 FR18 Control Room Fire Scenario 18 8.30E-08 1.06 4.52E-09 Z047X Fire Zone 047 Scenario X 3.58E-07 4.55 1.76E-08 FLECW ECW Failure Due to Breach of MGR 2.83E-07 3.60 3.03E-08 Z071X Fire Zone 071 Scenario X 2.07E-07 2.63 4.34E-09 Z047B Fire Zone 047 Scenario B 1.60E-07 2.04 7.59E-09 Z47BC Fire Zone 047 Scenario BC 6.24E-08 0.79 3.06E-09 SEIS3 Seismic Event, 0.4g Acceleration 3.93E-08 0.50 2.02E-09 FR23 Control Room Fire Scenario 23 2.29E-08 0.29 2.79E-10 SEIS4 Seismic Event, 0.6g Acceleration 2.02E-08 0.26 8.11E-10 Z1470 Fire Zone 147 Scenario 0 7.03E-09 0.09 3.02E-11 FL26 External Flooding Scenarios 2 Through 6 9.23E-09 0.12 8.81E-10 SEIS2 Seismic Event, 0.2g Acceleration 9.15E-09 0.12 3.02E-10 SEIS1 Seismic Event, 0.1 g Acceleration 1.74E-09 0.02 1.29E-11 FR10 Control Room Fire Scenario 1 O 1.02E-09 0.01 1.15E-11 FL 1 Flood Induced LOOP -Scenario 1 9.93E-10 0.01 5.88E-11 Group Subtotal 2.34E-06 29.81 1.88E-07 %LERF 24.55 0.96 3.72 6.41 0.92 1.61 0.65 0.43 0.06 0.17 0.01 0.19 0.06 0.00 0.00 0.01 39.75 Initiating Events Loss of Coolant Accidents ELOCA Excessive LOCA RCPL RCP Seal LOCA MLOCA Medium LOCA ILOCA lsolable Small LOCA SLOCA Non-lsolable Small LOCA LLOCA Large LOCA RCR2 2 or More RCS SRVs Open RCRV One RCS SRV Opens VSEQ Interfacing Systems LOCA Group Subtotal Loss of Offsite Power Events LOO PG Loss of Offsite Power Grid Related LOO PP Loss of Offsite Power Plant Centered LOOPS Loss of Offsite Power Switchyard Related LOO PW Loss of Offsite Power Weather Related Group Subtotal Steam Generator Tube Rupture SGTR Steam Generator Tube Rupture Group Subtotal Loss of Support Systems L1DCB Loss of DC Bus E1 B11 L1DCA Loss of DC Bus E1A11 LOEAB3 LOEAB6 Loss of EAB HVAC, BC/AB/ACRUN, All Support LOEAB9 LOEAB2 LOEAB5 Loss of EAB HVAC, BC/AB/ACRUN, HVAC A/C/B=F LOEAB8 LOECW2 LOECW5 Loss of ECW, BC/AB/ACRUN, ECW A/C/B=F LOECW8 GDF %GDF 3.13E-07 3.97 1.82E-07 2.32 1.11 E-07 1.41 4.26E-08 0.54 2.09E-08 0.27 2.40E-08 0.31 4.27E-11 0.00 3.56E-11 0.00 4.91E-12 0.00 6.93E-07 8.81 6.36E-07 8.09 5.32E-08 0.68 1.39E-06 17.73 6.39E-07 8.12 2.72E-06 34.62 5.51E-07 7.00 5.51E-07 7.00 7.86E-08 1.00 8.14E-08 1.04 5.36E-08 0.68 2.79E-08 0.35 2.79E-08 0.35 1.01 E-08 0.13 1.01 E-08 0.13 1.01 E-08 0.13 2.36E-08 0.30 2.36E-08 0.30 2.36E-08 0.30 Enclosure NOC-AE-16003412 Page 3 of 4 LERF %LERF 2.84E-10 0.06 5.48E-09 1.16 O.OOE+OO 0.00 1.47E-09 0.31 5.05E-10 0.11 1.20E-11 0.00 O.OOE+OO 0.00 O.OOE+OO 0.00 4.24E-12 0.00 7.76E-09 1.64 4.09E-08 8.66 3.18E-09 0.67 8.92E-08 18.88 4.09E-08 8.66 1.74E-07 36.86 8.66E-09 1.83 8.66E-09 1.83 2.25E-09 0.48 2.41 E-09 0.51 2.22E-09 0.47 1.92E-09 0.41 1.92E-09 0.41 6.83E-10 0.14 6.83E-10 0.14 6.83E-10 0.14 1.54E-09 0.33 1.55E-09 0.33 1.54E-09 0.33 Initiating Events LOECW3 LOECW6 Loss of ECW, BC/AB/ACRUN, All Support LOECW9 LOCR3 LOCR6 Loss ofCRE HVAC, BC/AB/ACRUN, All Support LOCR9 LOCR2 LOCR5 Loss of CRE HVAC, BC/AB/ACRUN, HVAC A/C/B=F LOCR8 LOCCW2 LOCCW5 Loss of CCW, BC/AB/ACRUN, CCW A/C/B=F LOCCW8 LOCCW3 LOCCW6 Loss of CCW, BC/AB/ACRUN, All Support LOCCW9 Group Subtotal General Transients SLBD Steam Line Break Outside Containment TIRIP Turbine Trip PLMFW Partial Loss of Main Feedwater RTRIP Reactor Trip LOPF Loss of Primary Flow SLBI Steam Line Break Inside Containment EXMFW Excessive Feedwater Flow IMSIV Closure of One MSIV TLMFW Total Loss of Main Feedwater LCV Loss of Condenser Vacuum SI Inadvertent Safety Injection AMSIV Closure of All MSIV's LOIA Loss of Instrument Air FLBO Feed Line Break in the IVC MSV MS Relief or Safety Valve Opening Group Subtotal Total Reported Frequencies of the Group: GDF %GDF 2.83E-09 0.04 2.50E-09 0.03 2.50E-09 0.03 8.30E-09 0.11 8.04E-09 0.10 8.04E-09 0.10 1.54E-09 0.02 1.54E-09 0.02 1.54E-09 0.02 1.55E-10 0.00 1.91E-10 0.00 1.38E-10 0.00 7.22E-10 0.01 5.67E-10 0.01 5.67E-10 0.01 4.10E-07 5.21 1.74E-07 2.21 2.61 E-07 3.31 2.46E-07 3.12 2.81 E-07 3.58 7.81 E-08 0.99 1.72E-08 0.22 2.59E-08 0.33 6 55E-09 0.08 1.94E-08 0.25 1.47E-08 0.19 5.75E-09 0.07 6.00E-09 0.08 4.06E-09 0.05 2.21 E-09 0.03 2.18E-09 0.03 1.14E-06 14.54 7.86E-06 100.00 Enclosure NOC-AE-16003412 Page 4 of 4 LERF %LERF 1.67E-10 0.04 1.63E-10 0.03 1.63E-10 0.03 1.51E-10 0.03 1.48E-10 0.03 1.48E-10 0.03 3.02E-11 0.01 3.02E-11 0.01 2.50E-11 0.01 O.OOE+OO 0.00 1.52E-12 0.00 O.OOE+OO 0.00 4.25E-12 0.00 4.24E-12 0.00 4.91E-12 0.00 1.84E-08 3.90 1.53E-08 3.24 1.68E-08 3.56 1.44E-08 3.05 1.82E-08 3.85 4.91 E-09 1.04 1.02E-09 0.22 1.50E-09 0.32 3.50E-10 0.07 1.08E-09 0.23 9.69E-10 0.21 5.06E-10 0.11 3.21E-10 0.07 1.81E-10 0.04 6.66E-11 0.01 9.89E-11 0.02 7.57E-08 16.02 4.73E-07 100.00}}

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