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MONTHYEARML18096A9362018-04-0404 April 2018 License Amendment Request to Adopt NFPA-805 Performance Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition) Project stage: Request ML18096A9552018-04-0404 April 2018 License Amendment Request to Adopt NFPA-805 Performance Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition) Project stage: Other NL-17-1962, Application to Adopt 10 CFR 50.69, Risk-informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors.2018-06-0707 June 2018 Application to Adopt 10 CFR 50.69, Risk-informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors. Project stage: Request ML18228A8352018-08-22022 August 2018 Online Reference Portal for License Amendment Request to Adopt National Fire Protection Association Standard 805 Project stage: Other ML19029B3402019-01-23023 January 2019 Southern Nuclear Operating Company, Edwin I. Hatch Nuclear Plant, Unit Nos. 1 and 2 Draft Request for Additional Information for the License Amendment Requests to Adopt the Risk-Informed Provisions of Title 10 of the Code of Federal Regulat Project stage: Draft RAI ML19018A2312019-01-23023 January 2019 Edwin Hatch 1 & 2 - Regulatory Audit in Support of the License Amendment Requests to Implement a Risk-Informed, Performance-based, Fire Protection Program Project stage: Other ML19088A0092019-03-29029 March 2019 NRR E-mail Capture - Hatch 1 and 2 - LAR to Adopt NFPA 805 Fire Protection Standard, EPID L-2018-LLA-0107, Request for Additional Information Project stage: RAI ML19220A0362019-08-0808 August 2019 NRR E-mail Capture - RAI - Edwin I. Hatch Nuclear Plant, LAR Regarding Adoption of NFPA 805, Request for Additional Information, EPID L-2018-LLA-0107 Project stage: RAI NL-19-1203, Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 8052019-10-0707 October 2019 Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 805 Project stage: Request ML20066F5922020-06-11011 June 2020 Issuance of Amendments Nos. 304 and 249, Regarding License Amendment Request to Adopt NFPA-805 Performance Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants (2001 Edition) Project stage: Approval ML20167A0132020-06-17017 June 2020 Correction of Amendments Nos. 304 & 249 License Amendment Request to Adopt NFPA-805 Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants, 2001 EPID L-2018-LLA-0107 Project stage: Other 2019-10-07
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Similar Documents at Hatch |
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Category:Letter type:NL
MONTHYEARNL-24-0014, Revised Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical.2024-01-30030 January 2024 Revised Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical. NL-23-0889, Units 1 and 2 - License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times for Residual Heat Removal Service Water (RHRSW) and Plant Service Water (Psw) Systems2023-12-0606 December 2023 Units 1 and 2 - License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times for Residual Heat Removal Service Water (RHRSW) and Plant Service Water (Psw) Systems NL-23-0879, Request for Exemption from Security Event Notification Implementation2023-11-29029 November 2023 Request for Exemption from Security Event Notification Implementation NL-23-0841, Update to Notice of Intent to Pursue Subsequent License Renewal2023-11-20020 November 2023 Update to Notice of Intent to Pursue Subsequent License Renewal NL-23-0658, Southern Nuclear Operating Company - Response to Request for Additional Information Regarding Quality Assurance Topical Report Submittal2023-08-11011 August 2023 Southern Nuclear Operating Company - Response to Request for Additional Information Regarding Quality Assurance Topical Report Submittal NL-23-0542, CFR 50.46 ECCS Evaluation Model Annual Report for 20222023-08-0909 August 2023 CFR 50.46 ECCS Evaluation Model Annual Report for 2022 NL-23-0624, Report of Changes to Emergency Plan and Summary of 50.54(q) Analysis2023-08-0404 August 2023 Report of Changes to Emergency Plan and Summary of 50.54(q) Analysis NL-23-0566, ISFSI and Edwin I. Hatch Nuclear Plant ISFSI - Registration of Spent Fuel Cask Use2023-07-13013 July 2023 ISFSI and Edwin I. Hatch Nuclear Plant ISFSI - Registration of Spent Fuel Cask Use NL-23-0555, Request for Exemption from Physical Barrier Requirement2023-07-0707 July 2023 Request for Exemption from Physical Barrier Requirement NL-23-0444, Quality Assurance Topical Report Submittal2023-06-15015 June 2023 Quality Assurance Topical Report Submittal NL-23-0457, ISFSI, and Edwin I. Hatch Nuclear Plant, ISFSI - Registration of Spent Fuel Cask Use2023-06-12012 June 2023 ISFSI, and Edwin I. Hatch Nuclear Plant, ISFSI - Registration of Spent Fuel Cask Use NL-23-0422, Inservice Inspection Program Owner'S Activity Report for Refueling Outage 2R272023-05-30030 May 2023 Inservice Inspection Program Owner'S Activity Report for Refueling Outage 2R27 NL-23-0383, SNC Response to Regulatory Issue Summary 2023-01:Preparation And.2023-05-19019 May 2023 SNC Response to Regulatory Issue Summary 2023-01:Preparation And. NL-23-0372, Units 1 & 2, Joseph M. Farley Nuclear Plant - Units 1 & 2, Vogtle Electric Generating Plant - Units 1 & 2, Annual Radiological Environmental Operating Reports for 20222023-05-10010 May 2023 Units 1 & 2, Joseph M. Farley Nuclear Plant - Units 1 & 2, Vogtle Electric Generating Plant - Units 1 & 2, Annual Radiological Environmental Operating Reports for 2022 NL-23-0310, Annual Non-Radiological Environmental Operating Reports and Annual Radioactive Effluent Release Reports for 20222023-04-25025 April 2023 Annual Non-Radiological Environmental Operating Reports and Annual Radioactive Effluent Release Reports for 2022 NL-23-0019, GEN-ISI-ALT-2023-01, Request to Use Provision of a Later Edition of the ASME Boiler and Pressure Vessel Code, Section XI2023-04-12012 April 2023 GEN-ISI-ALT-2023-01, Request to Use Provision of a Later Edition of the ASME Boiler and Pressure Vessel Code, Section XI NL-23-0263, Southern Nuclear Company Submittal of Drug and Alcohol Testing Errors Identified 10 CFR 26.719(c) 30-Day Report2023-04-0505 April 2023 Southern Nuclear Company Submittal of Drug and Alcohol Testing Errors Identified 10 CFR 26.719(c) 30-Day Report NL-23-0208, Independent Spent Fuel Storage Installation ISFSI, Decommissioning Funding Plan Triennial Update2023-03-29029 March 2023 Independent Spent Fuel Storage Installation ISFSI, Decommissioning Funding Plan Triennial Update NL-23-0014, Southern Nuclear Operating Co Submittal of Report on Status of Decommissioning Funding2023-03-29029 March 2023 Southern Nuclear Operating Co Submittal of Report on Status of Decommissioning Funding NL-23-0228, Nuclear Property Insurance Coverage as of April 1, 2023 and Licensee Guarantees of Payment of Deferred Premiums (10 CFR 140.21)2023-03-20020 March 2023 Nuclear Property Insurance Coverage as of April 1, 2023 and Licensee Guarantees of Payment of Deferred Premiums (10 CFR 140.21) NL-23-0179, National Pollutant Discharge Elimination System (NPDES) Permit Renewal2023-03-13013 March 2023 National Pollutant Discharge Elimination System (NPDES) Permit Renewal NL-23-0101, Cycle 28 Core Operating Limits Report Version 12023-02-23023 February 2023 Cycle 28 Core Operating Limits Report Version 1 NL-23-0003, Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 12023-01-20020 January 2023 Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1 NL-23-0069, Correction of Technical Specification Omission and Typographical Error2023-01-20020 January 2023 Correction of Technical Specification Omission and Typographical Error NL-22-0316, Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable2022-11-30030 November 2022 Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable NL-22-0850, Supplement to License Amendment Request to Revise the NFPA 805 Fire Protection Program2022-11-18018 November 2022 Supplement to License Amendment Request to Revise the NFPA 805 Fire Protection Program NL-22-0832, Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF .2022-10-27027 October 2022 Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF . NL-22-0800, Supplement to Authorized Relief Request HNP-ISI-RR-05-022022-10-27027 October 2022 Supplement to Authorized Relief Request HNP-ISI-RR-05-02 NL-22-0801, Response to Request for Additional Information Regarding: Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of .2022-10-14014 October 2022 Response to Request for Additional Information Regarding: Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of . NL-22-0757, Units 1 & 2, Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2022-09-30030 September 2022 Units 1 & 2, Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b NL-22-0687, Notice of Intent to Pursue Subsequent License Renewal for Hatch Units 1 & 22022-08-31031 August 2022 Notice of Intent to Pursue Subsequent License Renewal for Hatch Units 1 & 2 NL-22-0406, Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1.1-1, Modes2022-08-19019 August 2022 Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1.1-1, Modes NL-22-0650, Units 1 and 2 - Response to Request for Confirmation of Information Regarding License Amendment Request to Revise the NFPA 805 Fire Protection Program2022-08-19019 August 2022 Units 1 and 2 - Response to Request for Confirmation of Information Regarding License Amendment Request to Revise the NFPA 805 Fire Protection Program NL-22-0590, Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Exten2022-08-18018 August 2022 Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Exten NL-22-0672, Registration of Spent Fuel Cask Use2022-08-17017 August 2022 Registration of Spent Fuel Cask Use NL-22-0564, and Vogtle Electric Generating Plant, Registration of Spent Fuel Cask Use2022-07-21021 July 2022 and Vogtle Electric Generating Plant, Registration of Spent Fuel Cask Use NL-22-0510, Plants Units 1 and 2, 10 CFR 50.46 ECCS Evaluation Model Annual Report for 20212022-07-14014 July 2022 Plants Units 1 and 2, 10 CFR 50.46 ECCS Evaluation Model Annual Report for 2021 NL-22-0499, Registration of Spent Fuel Cask Use2022-06-27027 June 2022 Registration of Spent Fuel Cask Use NL-22-0362, Southern Nuclear Operating Company, Inc. - Foreign Ownership, Control, or Influence Five-Year Renewal Filing and NRC Facility Clearance Update2022-06-0101 June 2022 Southern Nuclear Operating Company, Inc. - Foreign Ownership, Control, or Influence Five-Year Renewal Filing and NRC Facility Clearance Update NL-22-0365, Inservice Inspection Program Owner'S Activity Report (OAR-1) for Outage 1R302022-05-31031 May 2022 Inservice Inspection Program Owner'S Activity Report (OAR-1) for Outage 1R30 NL-22-0335, Supplement to Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of Time to Reach Mode 2 in LCO 3.0.3 And.2022-05-17017 May 2022 Supplement to Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of Time to Reach Mode 2 in LCO 3.0.3 And. NL-22-0344, Annual Radiological Environmental Operating Reports for 20212022-05-10010 May 2022 Annual Radiological Environmental Operating Reports for 2021 NL-22-0315, Technical Specification 5.6.6 Post Accident Monitoring Instrumentation Report for Drywell Temperature Indicator Inoperable for Greater than 30 Days2022-05-0404 May 2022 Technical Specification 5.6.6 Post Accident Monitoring Instrumentation Report for Drywell Temperature Indicator Inoperable for Greater than 30 Days NL-22-0325, Withdrawal of Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable2022-05-0303 May 2022 Withdrawal of Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable NL-22-0283, Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - Ritstf.2022-04-29029 April 2022 Supplement to License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - Ritstf. NL-22-0271, Changes to the Physical Security Plan2022-04-19019 April 2022 Changes to the Physical Security Plan NL-22-0240, SNC Response to Regulatory Issue Summary 2022-01: Preparation and Scheduling of Operator Licensing Examinations2022-03-31031 March 2022 SNC Response to Regulatory Issue Summary 2022-01: Preparation and Scheduling of Operator Licensing Examinations NL-21-0918, License Amendment Request to Revise the NFPA 805 Fire Protection Program. with Attachments 3 to 52022-03-31031 March 2022 License Amendment Request to Revise the NFPA 805 Fire Protection Program. with Attachments 3 to 5 NL-22-0220, Units 1 and 2 - Nuclear Property Insurance Coverage as of April 1, 20222022-03-28028 March 2022 Units 1 and 2 - Nuclear Property Insurance Coverage as of April 1, 2022 NL-22-0221, Licensee Guarantees of Payment of Deferred Premiums (10 CFR 140.21)2022-03-28028 March 2022 Licensee Guarantees of Payment of Deferred Premiums (10 CFR 140.21) 2024-01-30
[Table view] Category:Response to Request for Additional Information (RAI)
MONTHYEARNL-24-0014, Revised Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical.2024-01-30030 January 2024 Revised Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical. NL-23-0658, Southern Nuclear Operating Company - Response to Request for Additional Information Regarding Quality Assurance Topical Report Submittal2023-08-11011 August 2023 Southern Nuclear Operating Company - Response to Request for Additional Information Regarding Quality Assurance Topical Report Submittal NL-23-0003, Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 12023-01-20020 January 2023 Response to Request for Additional Information Regarding License Amendment Request to Relax the Required Number of Fully Tensioned Reactor Pressure Vessel Head Closure Studs in Technical Specification Table 1 NL-22-0801, Response to Request for Additional Information Regarding: Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of .2022-10-14014 October 2022 Response to Request for Additional Information Regarding: Application to Revise Technical Specifications to Adopt Technical Specifications Task Force (TSTF) Traveler TSTF-208, Revision 0, Extension of . NL-22-0650, Units 1 and 2 - Response to Request for Confirmation of Information Regarding License Amendment Request to Revise the NFPA 805 Fire Protection Program2022-08-19019 August 2022 Units 1 and 2 - Response to Request for Confirmation of Information Regarding License Amendment Request to Revise the NFPA 805 Fire Protection Program NL-22-0590, Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Exten2022-08-18018 August 2022 Response to Request for Additional Information Regarding License Amendment Request to Revise Technical Specifications to Adopt Risk Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Exten NL-21-0862, Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable - RAI Responses2021-09-23023 September 2021 Emergency License Amendment Request for Technical Specification 3.7.2 Regarding One-Time Extension of Completion Time for Plant Service Water (Psw) Pump Inoperable - RAI Responses NL-21-0423, Emergency License Amendment Request for Technical Specification 3.5.1 Re One-Time Extension of Completion Time for 2D RHR Pump - PRA RAI Response2021-04-22022 April 2021 Emergency License Amendment Request for Technical Specification 3.5.1 Re One-Time Extension of Completion Time for 2D RHR Pump - PRA RAI Response NL-21-0415, Emergency License Amendment Request for Technical Specification 3.5.1 Regarding One-Time Extension of Completion Time for 2D RHR Pump - RAI Response2021-04-20020 April 2021 Emergency License Amendment Request for Technical Specification 3.5.1 Regarding One-Time Extension of Completion Time for 2D RHR Pump - RAI Response NL-20-1273, Response to NRC Requests for Information License Amendment Request to Revise the Emergency Plan to Change Staffing and Extend Staff Augmentation Times for2020-11-20020 November 2020 Response to NRC Requests for Information License Amendment Request to Revise the Emergency Plan to Change Staffing and Extend Staff Augmentation Times for NL-20-1000, Responses to NRC Requests for Additional Information to License Amendment Request to Revise the Required Actions of Technical Specifications 3.8.1, AC Sources - Operating, for One-Time Extension of Completion Time2020-08-23023 August 2020 Responses to NRC Requests for Additional Information to License Amendment Request to Revise the Required Actions of Technical Specifications 3.8.1, AC Sources - Operating, for One-Time Extension of Completion Time NL-20-0670, Response to Request for Additional Information (RAI) Regarding Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors2020-06-0202 June 2020 Response to Request for Additional Information (RAI) Regarding Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors NL-20-0640, Response to Request for Additional Information for Exemption Request2020-05-27027 May 2020 Response to Request for Additional Information for Exemption Request NL-19-1248, Revise Technical Specification Requirements During Handling Irradiated Fuel and Core Alterations - TSTF-51, SNC Response to NRC Request for Additional Information2019-10-17017 October 2019 Revise Technical Specification Requirements During Handling Irradiated Fuel and Core Alterations - TSTF-51, SNC Response to NRC Request for Additional Information NL-19-1203, Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 8052019-10-0707 October 2019 Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 805 NL-19-1028, Response to NRC Request for Additional Information Concerning License Amendment Request for Technical Specifications 3.3.8.1 and 3.8.1 Regarding Unit 1 Degraded Voltage Protection2019-08-28028 August 2019 Response to NRC Request for Additional Information Concerning License Amendment Request for Technical Specifications 3.3.8.1 and 3.8.1 Regarding Unit 1 Degraded Voltage Protection NL-19-0850, Response to Request for Addition Information Regarding Application to Adopt Title 10 of Code of Federal Regulations (CFR) 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and ...2019-07-16016 July 2019 Response to Request for Addition Information Regarding Application to Adopt Title 10 of Code of Federal Regulations (CFR) 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and ... NL-19-0698, License Amendment Request to Correct Non-Conservative Technical Specification Allowable Values for the Condensate Storage Tank Low Level Transfer Function SNC Response to NRC Request for ...2019-06-12012 June 2019 License Amendment Request to Correct Non-Conservative Technical Specification Allowable Values for the Condensate Storage Tank Low Level Transfer Function SNC Response to NRC Request for ... NL-19-0188, Emergency License Amendment Request for Technical Specification 3.8.1 Regarding Voltage Limit Increase for Emergency Diesel Generator Load Rejection Surveillance Test SNC Response to NRC Request...2019-02-20020 February 2019 Emergency License Amendment Request for Technical Specification 3.8.1 Regarding Voltage Limit Increase for Emergency Diesel Generator Load Rejection Surveillance Test SNC Response to NRC Request... NL-18-1514, Response to Request for Information Regarding License Amendment Request to Revise Technical Specification 5.2.2.g and Update Emergency Plan Minimum On-Shift.2019-01-31031 January 2019 Response to Request for Information Regarding License Amendment Request to Revise Technical Specification 5.2.2.g and Update Emergency Plan Minimum On-Shift. NL-19-0009, Supplemental Response to Alternative Request HNP-ISI-ALT-05-042019-01-0808 January 2019 Supplemental Response to Alternative Request HNP-ISI-ALT-05-04 NL-18-1480, Response to NRC Request for Additional Information on Alternative Request (HNP-ISI-ALT-05-04)2018-11-29029 November 2018 Response to NRC Request for Additional Information on Alternative Request (HNP-ISI-ALT-05-04) NL-18-0639, Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension2018-05-10010 May 2018 Response to Request for Information Regarding Safety Relief Valve Main Valve Body Testing Extension NL-18-0541, Response to Request for Additional Information for Alternative RR-V-11 Regarding Main Steam Safety Valve Testing Requirements2018-04-17017 April 2018 Response to Request for Additional Information for Alternative RR-V-11 Regarding Main Steam Safety Valve Testing Requirements ML18088A0802018-03-29029 March 2018 Response to Request for Additional Information for Alternative RR-V-11 Regarding Main Steam Safety Valve Testing Requirements NL-18-0211, Response to Request for Additional Information Regarding Alternative HNP-181-ALT-05-05 to Adopt Code Case N-7022018-02-20020 February 2018 Response to Request for Additional Information Regarding Alternative HNP-181-ALT-05-05 to Adopt Code Case N-702 NL-18-0085, Response to NRC RAIs Regarding Generic Letter 2016-012018-02-0505 February 2018 Response to NRC RAIs Regarding Generic Letter 2016-01 NL-17-2015, Response to NRC RAIs Regarding Decommissioning Funding Status Reports2018-01-22022 January 2018 Response to NRC RAIs Regarding Decommissioning Funding Status Reports NL-17-1161, License Amendment Request to Revise Technical Specification Section 5.5.12 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies Supplemental Responses to NRC Second Set of Requests for Additional Information2017-07-12012 July 2017 License Amendment Request to Revise Technical Specification Section 5.5.12 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies Supplemental Responses to NRC Second Set of Requests for Additional Information NL-17-0766, License Amendment Request to Revise Technical Specification Section 5.5.12 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies, Responses to NRC Second Set of Requests for Additional Information2017-06-0101 June 2017 License Amendment Request to Revise Technical Specification Section 5.5.12 for Permanent Extension of Type a and Type C Leak Rate Test Frequencies, Responses to NRC Second Set of Requests for Additional Information NL-17-0917, Response to Request for Additional Information Regarding Relief Requests RR-16, RR-17. RR-21 and RR-222017-05-31031 May 2017 Response to Request for Additional Information Regarding Relief Requests RR-16, RR-17. RR-21 and RR-22 NL-17-0063, Response to Verbal Request for Additional Information on Technical Specifications Revision Request to Implement TSTF-500, DC Electrical Re-write2017-02-0606 February 2017 Response to Verbal Request for Additional Information on Technical Specifications Revision Request to Implement TSTF-500, DC Electrical Re-write NL-16-2494, Units 1 and 2 - Spent Fuel Pool Evaluation Supplemental Report, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from ...2016-12-15015 December 2016 Units 1 and 2 - Spent Fuel Pool Evaluation Supplemental Report, Response to NRC Request for Information Pursuant to 10 CFR 50.54(f) Regarding Recommendation 2.1 of the Near-Term Task Force Review of Insights from ... NL-16-2457, Supplemental Information Regarding Proposed Safety Limit Minimum Critical Power Ratio (SLMCPR) License Amendment2016-11-18018 November 2016 Supplemental Information Regarding Proposed Safety Limit Minimum Critical Power Ratio (SLMCPR) License Amendment NL-16-2109, Response to Request for Additional Information on Technical Specifications Revision Request to Implement TSTF-500. DC Electrical Re-write2016-11-16016 November 2016 Response to Request for Additional Information on Technical Specifications Revision Request to Implement TSTF-500. DC Electrical Re-write NL-16-1830, Southern Nuclear Operating Company Response to RAI for License Amendment Regarding Emergency Action Level Schemes to Adopt NEI 99-01 Rev 6 and to Modify Radiation Monitors at Farley Nuclear Plant, Part 1B of 1C2016-11-0303 November 2016 Southern Nuclear Operating Company Response to RAI for License Amendment Regarding Emergency Action Level Schemes to Adopt NEI 99-01 Rev 6 and to Modify Radiation Monitors at Farley Nuclear Plant, Part 1B of 1C NL-16-1830, Southern Nuclear Operating Company Response to RAI for License Amendment Regarding Emergency Action Level Schemes to Adopt NEI 99-01 Rev 6 and to Modify Radiation Monitors at Farley Nuclear Plant, Part 1C of 1C2016-11-0303 November 2016 Southern Nuclear Operating Company Response to RAI for License Amendment Regarding Emergency Action Level Schemes to Adopt NEI 99-01 Rev 6 and to Modify Radiation Monitors at Farley Nuclear Plant, Part 1C of 1C ML16314A5052016-11-0303 November 2016 Southern Nuclear Operating Company Response to RAI for License Amendment Regarding Emergency Action Level Schemes to Adopt NEI 99-01 Rev 6 and to Modify Radiation Monitors at Farley Nuclear Plant, Part 1B of 1C NL-16-1169, Response to Request for Additional Information on Technical Specifications - Revision Request to Implement TSTF-500, DC Electrical Re-Write.2016-08-12012 August 2016 Response to Request for Additional Information on Technical Specifications - Revision Request to Implement TSTF-500, DC Electrical Re-Write. NL-16-0628, Southern Nuclear Operating Company Response to Third Request for Additional Information Regarding Standard Emergency Plan: Cover Letter, Attachment 1 and Enclosures 1 - 102016-06-0909 June 2016 Southern Nuclear Operating Company Response to Third Request for Additional Information Regarding Standard Emergency Plan: Cover Letter, Attachment 1 and Enclosures 1 - 10 NL-16-0739, Corrected Response to Second Request for Additional Information Regarding Standard Emergency Plan2016-05-26026 May 2016 Corrected Response to Second Request for Additional Information Regarding Standard Emergency Plan NL-16-0660, Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specification Amendment Request2016-05-16016 May 2016 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specification Amendment Request NL-16-0655, Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request2016-05-0909 May 2016 Response to Request for Additional Information on Secondary Containment Drawdown Time Technical Specifications Amendment Request NL-16-0292, Response to Request for Additional Information on Revision to Secondary Containment Drawdown Time Technical Specifications Amendment Request2016-03-16016 March 2016 Response to Request for Additional Information on Revision to Secondary Containment Drawdown Time Technical Specifications Amendment Request NL-16-0169, Southern Nuclear Operating Company Response to First Request for Additional Information Re Standard Emergency Plan. Attachment 1: SNC Response to NRC RAI-1 Fleet Standard Emergency Plan and Enclosure 1: Evaluation of Proposed Changes Encl2016-02-17017 February 2016 Southern Nuclear Operating Company Response to First Request for Additional Information Re Standard Emergency Plan. Attachment 1: SNC Response to NRC RAI-1 Fleet Standard Emergency Plan and Enclosure 1: Evaluation of Proposed Changes Enclos ML16060A3282016-02-17017 February 2016 Southern Nuclear Operating Company Response to First Request for Additional Information Re Standard Emergency Plan. Attachment 1: SNC Response to NRC RAI-1 Fleet Standard Emergency Plan and Enclosure 1: Evaluation of Proposed Changes Enclos NL-16-0172, Response to Request for Information Regarding Changes to Technical Specification Section 1.0, 3.4.9, and 5.02016-02-0909 February 2016 Response to Request for Information Regarding Changes to Technical Specification Section 1.0, 3.4.9, and 5.0 NL-15-2270, Response to Request for Additional Information for Alternative HNP-ISI-ALT-5-012015-12-16016 December 2015 Response to Request for Additional Information for Alternative HNP-ISI-ALT-5-01 NL-15-2047, Response to Second Request for Additional Information Regarding SNC License Amendment Request for TSTF-523, Revision 22015-11-24024 November 2015 Response to Second Request for Additional Information Regarding SNC License Amendment Request for TSTF-523, Revision 2 ML15322A0902015-11-12012 November 2015 Enclosure 4, Non-Proprietary Version of the Epri/Bwrvip Information Requested in RAI 1 2024-01-30
[Table view] |
Text
~ Southern Nuclear Cheryl A. Gayheart Regulatory Alla1rs D1rector Vi"\:\ Clllllnn,l<k f',u k w.1y B11 nnngh.1111 AL >)2.\1 20' Y92 )1f6 OCT 0 7 2019 c:.tg~yh~J@,nullicm~o.com Docket Nos.: 50-321 NL-19-1203 50-366 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant - Units 1 and 2 Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 805 Ladies and Gentlemen:
By letter dated April 4, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18096A936), Southern Nuclear Operating Company (SNC) submitted a license amendment request (LAR) for the Edwin I. Hatch Nuclear Plant (HNP),
Units 1 and 2, to adopt National Fire Protection Association Standard 805 (NFPA 805),
"Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants," 2001 Edition (ADAMS Accession No. ML010800360), as incorporated into Title 10 of the Code of Federal Regulations, Part 50, Section 50.48(c). On March 29, 2019 the U.S.
Nuclear Regulatory Commission (NRC) staff issued requests for additional information (RAis)
(ADAMS Accession No. ML19088A009) to SNC. On May 28, 2019, SNC responded to those RAis (ADAMS Accession No. ML19151A421).
By electronic correspondence dated August 8, 2019, the NRC staff issued RAis regarding SNC's May 28, 2019 response. The Enclosure provides the SNC response to the August 8, 2019 RAis.
The conclusions of the No Significant Hazards Consideration and Environmental Consideration contained in the original License Amendment Request (LAR) have been reviewed and are unaffected by this RAI response.
This letter contains no NRC commitments. If you have any questions, please contact Jamie Coleman at 205.992.6611.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the l 1h day of October 2019.
Respectfully submitted, C. A. a h rt Directo , Regulatory Affairs Southern Nuclear Operating Company CAG/RMJ
U.S. Nuclear Regulatory Commission NL-19-1203 Page 2
Enclosure:
SNC Response to NRC RAis cc: Regional Administrator, Region II NRR Project Manager- Hatch Senior Resident Inspector- Hatch Director, Environmental Protection Division - State of Georgia RType: CHA02.004
Edwin I. Hatch Nuclear Plant- Units 1 and 2 Response to Request to Additional Information Regarding Application to Adopt National Fire Protection Association Standard 805 Enclosure SNC Response to NRC RAis
Enclosure to NL-19-1203 SNC Response to NRC RAis PRA RAI 05.01 - Update of Fire PRA when Modifications and Implementation are Complete In its letter dated May 28, 2019, SNC provided updated text for Implementation Item IMP-19 but did not include that same text in LAR AttachmentS, Table S-3. The NRC staff requests that SNC update LAR Attachment S, Table S-3 to reflect the wording of the updated Implementation Item IMP-19 provided on page E4-4 of its May 28, 20191etter.
SNC Response to PRA RAI 05.01 The updated Attachment was subsequently provided by SNC letter dated August 9, 2019.
PRA RAI 07.01- Treatment of Sensitive Electronics Screening Approach In its letter dated May 28, 2019, SNC explained that a screening approach was used to preclude internally inspecting each electrical cabinet to determine whether sensitive electronics exist that should be treated using a damage threshold of 3kW/m2. SNC explains that based on their function, certain cabinets were excluded from consideration such as switchgear, motor controlled centers (MCCs), and distribution cabinets, which implies that there are no sensitive electronics associated with switchgear, MCCs, and distribution cabinets; however, SNC did not state this. SNC also explains that "[f]ire risk is already bounded by the fire initiating event treatment (e.g., loss of the panel is bounded by assumed plant trip." The NRC staff interprets this statement to mean that failure of panels that lead only to a plant trip are already modeled in the fire probabilistic risk assessment (FPRA) as contributing to an initiating event, yet, the NRC staff notes that panels that lead to failures affecting plant shutdown need to be fully modeled to accurately account for their risk. In light of these observations, the NRC staff requests that SNC:
a) Clearly indicate whether cabinets screened from consideration based on their function such as switchgear, MCCs, and distribution cabinets do not house sensitive electronics.
If SNC cannot conclude that these cabinets do not contain sensitive electronics, then justify screening these cabinets from consideration for damage to sensitive electronics.
Otherwise adjust the aggregate analysis in response to PRA RAI 03.
b) Confirm that the panels screened because they are already modeled in the FPRA as contributing to plant trips do not also impact plant shutdown. If this conclusion cannot be reached, then justify screening these cabinets from consideration for damage to sensitive electronics. Otherwise, adjust the aggregate analysis in response to PRA RAI 03.
SNC Response to PRA RAI 07.01 a) The FPRA methodology for treatment of enclosed sensitive electronics will be updated so that electrical cabinets that contain sensitive electronics will not be screened based on the function of the electrical cabinet. Electrical cabinets that contain enclosed sensitive electronics will be treated as such in the FPRA. The results will be included in the aggregate analysis in response to PRA RAI 03. It should be noted that exposed sensitive electronics had already been identified and evaluated in accordance with NUREG/CR-6850 guidance.
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Enclosure to NL-19-1203 SNC Response to NRC RAts b) The FPRA assumes a plant trip for postulated fire scenarios. Failure of electrical cabinets that may result in a plant trip (e.g., turbine generator control cabinets) were therefore screened given the assumed plant trip modeling. Electrical cabinets that contain credited FPRA functions that may impact plant shutdown were not screened from consideration because of the assumed plant trip.
PRA RAI 08.01 - Consideration of Violations in Determining Influencing Factors In its letter dated May 28, 2019, SNC discussed violations that have occurred in the Cable Spreading Room (CSR), South East (SE) Corner Pump Room, East Cableway Foyer and SE Stairwell and sought to justify the transient influencing factors assigned to these areas. SNC explained that in the CSR, which was designated by a very low maintenance influencing factor, a single 1.5 foot wood two-by-four was found located between two cable trays. SNC further explained that the CSR is designated a Level A transient combustible area requiring permitting and that combustibles are not left unattended except for short periods of time up to an hour.
SNC further stated that the wood was likely inadvertently left behind after completion of maintenance work. The NRC staff notes that violations, although inadvertent, can contribute to fire risk. As SNC points out, use of a very low influencing factor requires that no violations have occurred in a reasonable period. In spite of the Level A transient combustible control requirement stated above, it is not clear to the NRC staff why the discovered existence of the section of the wooden two-by-four is not a violation and would not require assigning a higher maintenance influencing factor to the CSR. Therefore, the NRC staff requests that SNC:
a) Justify why the discovery of the wooden two-by-four is not a violation that would require assigning a higher maintenance influencing factor to the CSR. If it cannot be justified that the existence of the wood in the CSR cannot lead to a higher influencing factor for the CSR, then assign a higher maintenance influencing factor to the CSR in the aggregate analysis provided in your response to PRA RAt 03.
Additionally, the disposition for the three non-CSR violations appears to imply that a certain criterion in FAQ 12-0064 "Hot Work!fransient Fire Frequency Influence Factors," (ADAMS Accession No. ML12346A488), is met, though it is not clear from SNC's RAt response whether the criterion is met. Each of the three dispositions state "Per FAQ 12-0064, a low storage rating is to be used for an area where no combustible/flammable material are stored by practice but where combustibles may be introduced subject to a permitting process." However, SNC does not directly state that this criterion is met. Also, FAQ 12-0064 indicates that when assigning a low storage or maintenance influencing factor, that either no violations have occurred or a performance monitoring program is in place demonstrating that the administrative control programs are meeting expectations and objectives. In light of these observations, the NRC staff requests that SNC:
b) Confirm that for the three fire zones (i.e., Fire Zone 22058- SE Corner Pump Room, Fire Zone 1105- East Cableway Foyer, and Fire Zone 2103- SE Stairwell) where the violations cited above have occurred, no combustible/flammable material are stored by practice (though combustibles may be introduced subject to a permitting process).
c) Given that violations have occurred in Fire Zones 22508, 1105, and 2103, confirm that a performance monitoring program is in place demonstrating that the administrative control program is meeting expectations and objectives.
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Enclosure to NL-19-1203 SNC Response to NRC RAis d) If the criteria stipulated in part (b) and (c) above cannot be confirmed to be met then justify the assignment of a low storage and/or maintenance influencing factor for these three fire zones or use higher ratings in the aggregate analysis provided in your response to PRA RAI 03.
SNC Response to PRA RAI 08.01 a) A Medium storage influence factor per the guidance in FAQ 12-0064 will be assigned to the CSR because of the identification of the condition report related to the discovery of wood in the CSA. The results will be included in the aggregate analysis in response to PRA AAI 03.
b) In addition to the above, the following PAUs were also found to be in violation of the criteria considered for a FPAA "LOW" storage transient influencing factor per FAQ 12-0064 guidance: 22058, 1105, and 21 03. Based on this violation, the storage factor for these PAUs will be increased to Medium to account for the potential for combustible/flammable material. The results will be included in the aggregate analysis in response to PAA AAI 03.
c) The Transient Combustible Control procedure, NMP-ES-035-014, is in place to monitor the storage of combustible material, and have different restrictions based on the location and function of the area. Periodic reviews are performed based on the area to ensure that any violations are recorded and corrected per NMP-ES-035-009.
d) See part b of the AAI response above. The results of these changes will be included in the aggregated response to PAA AAI 03.
PRA RAI 15.b.01 - Change-in-Risk Calculations for Main Control Room (MCR)
Abandonment Scenarios In its letter dated May 28, 2019, SNC stated that change-in-risk calculations for MCA abandonment scenarios are performed in the same manner as other scenarios except that the assumption is made in the compliant plant model that "shutdown is being performed from the alternate shutdown panel." SNC also stated that failures that challenge this mode of safe shutdown or require a recovery action to mitigate failure that does not occur in the MCA or at a remote shutdown panel (ASP) are considered variances from deterministic requirements (VFDRs). Though the approach to identifying VFDAs for MCA abandonment scenarios is explained, SNC does not explain how the compliant plant is modeled versus how the post-transition plant is modeled. (For non-MCA abandonment scenarios, SNC states that basic events with a VFDA function are set to their nominal values, thus eliminating the VFDA by precluding the fire induced failure.)
SNC states that change-in-risk calculations for MCA abandonment scenarios are performed in the same manner as other scenarios except that:
"The compliant case modeling sets a lower bound limit on the [conditional core damage probability] CCDP to a minimum of 7E-02. This assumed value was justified by using the CCDP of an abandonment scenario due to loss of habitability with no PAA equipment failures. In some instances, this modeling assumption was implemented due to conservatism in the modeling logic for loss of control (LOC) and transferring to the ASP for compliant model scenarios only. In doing so, this assumption has established a quantified 'floor value' for a more accurate change in risk between the compliant case and the variant E-3
Enclosure to NL-19-1203 SNC Response to NRC RAis case. This assumption is considered conservative given the human error probability (HEP) for transferring control to the RSP is approximately 7E-02. No lower bound lim its were used for conditional large early release probability (CLERP) in the abandonment compliant cases."
Based on the above, the reason for conservatively limiting the compliant plant model CCDP in these scenarios to 7E-02 is not clear to the NRC staff. The cited statement appears to indicate that the modeling was performed to compensate for conservatism in the modeling logic for LOG and transferring to the RSP. The SNC response to PRA RAI13.c shows that CCDP for fires in the MCR or CSR ranges down to 1E-02 which is significantly lower than the proposed limit of 7E-02 used in the compliant plant model. NRC staff notes that conservatism in the compliant plant case can lead to underestimation of the change in-risk.
In light of these observations, the NRC staff request that the licensee address the following:
a) For MCR abandonment scenarios explain (1) how the post-transition plant is modeled, (2) how the compliant plant is modeled, (3) how the compliant plant modeling is different from the post-transition plant modeling, and (4) how the modeling of the compliant plant has the effect of removing the VFDRs.
b) Concerning the CCDP limit of 7E-02 used in MCR abandonment scenarios:
- i. Explain and justify the limit of 7E-02 used in MCR abandonment scenarios to limit the compliant plant model CCDP. Include an explanation for the statement "this modeling assumption was implemented due to conservatism in the modeling logic for LOG and transferring to the RSP."
ii. Justify that use of the proposed CCDP limit in the compliant plant model does not lead to underestimation of the change in-risk for these scenario SNC Response to NRC PRA RAI 15.b.01:
a)
(1) For MCR abandonment scenarios the post transition plant is modeled similarly to other PRA accident sequences. That is, fault tree logic is used to model the applicable success criteria, available functions, applicable failure modes, and required operator actions when establishing and using remote shutdown . A difference in the modeling is that the post transition plant abandonment scenarios do not include circuit failures for equipment available at a remote shutdown panel. The post transition plant PRA models the use of transfer switches at the remote shutdown panels to isolate circuit failures, and credits actions in the current remote shutdown procedures.
(2) For MCR abandonment scenarios the compliant plant is modeled similarly to the other fire area evaluations for non MCR abandonment scenarios. Each abandonment scenario in the post transition plant model is reviewed for fire induced cable impacts associated with VFDRs and the applicable component logic relationship is modified in the PRA software to represent a non-fire induced failure in the compliant plant model. As discussed above, given the MCR abandonment logic is included in the fault tree logic, the fire area evaluations are then performed similarly to those performed for other fire areas as described in SNC's response to RAI15.
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Enclosure to NL-19-1203 SNC Response to NRC RAis The MCR abandonment compliant plant model does include HRA challenges due to the timing associated with operators performing the necessary steps to establish functions at the remote shutdown panel. The PRA includes an assessment of the available and required time for operator actions during the fire risk evaluations.
(3) The compliant plant modeling is different from the post transition plant modeling in that local recovery actions are not required given there are no fire induced cable impacts in the compliant plant model. Otherwise, for MCR abandonment due to loss of habitability, the compliant and post transition plant modeling is similar. That is, only the functions available for remote shutdown are credited.
For MCR abandonment due to loss of control, the compliant plant model only credits the functions available for remote shutdown, because that is consistent with the fire area deterministic shutdown strategy. The post transition plant model credits available plant functions until a loss of control from the MCR is postulated and control is transferred to remote shutdown. Then, the post transition plant model is consistent with the compliant plant model and only the remote shutdown functions are credited.
(4) The difference in the plant models when the VFDRs are removed in the compliant plant model is that local operator actions are not required. Therefore, operator actions to establish remote shutdown require fewer procedure steps and less time to perform.
b)
- i. The MCR abandonment CCDP limit of 7E-02 for the compliant plant model was selected as a surrogate, because the CCDP was representative of the calculated CCDP for the fault tree logic when only the available remote shutdown functions are credited. The surrogate was used because in some scenarios it was identified that the LOC logic was resulting in conservative estimated CCDPs. This was occurring due to the way human failure events were being used in the non-abandonment and in the abandonment fault tree logic. For instance, a long term accident sequence operator action in the non-abandonment logic may not get the available credit once transferred to the remote shutdown logic, because the remote shutdown logic only includes a single action for a function (e.g., start torus cooling) and does not account for different available timings for the potential range of MCR abandonment postulated accident sequences.
ii. A surrogate MCR abandonment CCDP limit will no longer be used in the compliant model. The change in risk will be based on the calculated risk of the compliant and post transition plant models. This is consistent with the other fire area risk evaluations. These results will be included with the response to RAI 03.
PRA RAI 15.d.01 - Credit in the Change-in-Risk Calculation for Modifications In its letter dated May 28, 2019, SNC does not provide a sufficient explanation to the NRC staff to understand how modifications that do not resolve a VFDR but reduce the risk associated with a VFDR are credited. The response to PRA RAI 15.d stated:
"If the modification is associated with a VFDR, the delta risk calculation eliminates the variance via modification."
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Enclosure to NL-19-1203 SNC Response to NRC RAis The response further states:
" If the modification does not mitigate a specific VFDR the modification is credited in both the compliant and variant models to estimate the delta risk between the post transition plant and the compliant model."
The NRC staff notes that it is possible to propose a plant modification that is "associated" with a VFDR but does not fully resolve or mitigate that VFDR which appears to be the case for modification items 8, 9, 10 and 11 because LAR AttachmentS, Table S-2 states for these items that "This modification provides an improvement in delta (il) core damage frequency (CDF) and illarge early release frequency (LEAF)." Accordingly, it is not clear to the NRC staff whether implementation items 8, 9, 10 and 11 satisfy the first statement above or the second statement. It appears to the NRC staff that the cited implementation items satisfy neither statement since these implementation items do not appear to resolve a VFDR (and thus make the change-in-risk for the VFDR zero) and they do not appear to be credited in both the compliant and variant plant models because LAR AttachmentS, Table S-2 states that they provide an improvement in ilCDF and ilLERF.
In light of the above, explain how plant modifications modeled in the FPRA are credited in the compliant and post-transition plant models. Include discussion of modifications that resolve VFDRs, modifications that are not associated with a VFDR, and modifications that reduce the change-in-risk but do not fully resolve a VFDR.
SNC Response to PRA RAI 15.d.01:
As stated in LAR AttachmentS, Table S-2, implementation items 8, 9,10 and 11 are proposed cable reroutes on circuits associated with a VFDR for the purpose of reducing delta (il) core damage frequency (CDF) and illarge early release frequency (LEAF). Even though these modifications were credited for the purposes of reducing delta risk, they were implemented as stated in the response to RAI 15d. That is, the modifications were credited in the variant model and the compliant model. Therefore, after taking credit for the modification, the delta risk for the associated VFDR is zero. SNC did not implement any risk offsets or utilize any 'negative' delta risk calculations.
The FPRA credits modifications in the following way:
- Modification that resolve a VFDR - if the modification resolves a VFDR, the modification is credited in both the variant and compliant models. Therefore, after taking credit for the modification, the delta risk for the associated VFDR is zero.
- Modification not associated with a VFDR - if the modification is not associated with a VFDR, the modification is credited in both the variant and compliant models.
- Modification that reduces the change-in-risk but do not fully resolve a VFDR - no modifications were credited that reduce the change-in-risk but do not fully resolve a VFDR.
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Enclosure to NL-19-1203 SNC Response to NRC RAis PRA RAI 16.01 - Impact of Uncredited Systems on Transition Change-in-Risk In its letter dated May 28, 2019, SNC responded to PRA RAI 16 and stated that the extent of untraced cables is about 15% of the FPRA components with cables, and that components with untraced cables were treated in the FPRA by globally failing them in the compliant and post-transition plant FPRA models. SNC further explained that a sensitivity study was performed indicating that if these components were credited in the FPRA, there would be approximately a 25% reduction in the total FPRA risk due "largely to assuming failure of the feedwater system. SNC also explained that no VFDRs are associated with the feedwater system, and therefore, not crediting this system in the FPRA does not contribute to underestimation of the transition change-in-risk. However, SNC did not indicate whether there are any other uncredited components besides the feedwater system that are associated with a VFDR and could contribute to underestimation of the transition change-in-risk. SNC further stated that the impact from uncredited systems is "largely from the feedwater system but it is not clear to the NRC staff what the term "largely means (e.g., Does it mean 51% or 99.9% of the impact?) In light of the above, the NRC staff requests that SNC provide the following information:
a) Explain whether there are any other systems besides the feedwater system associated with a VFDR (i.e., systems that could contribute to underestimation of the transition change-in-risk), and justify that the impact of their exclusion from the FPRA compliant plant model on the transition change-in-risk is inconsequential.
b) If there are other systems besides the feedwater system associated with a VFDR that could contribute to underestimation of the transition change-in-risk and if this treatment cannot be justified in response to part (a) above, then replace this treatment with a more realistic treatment that does not underestimate the change-in-risk and provide the results in the integrated analysis requested in PRA RAI 03.
SNC Response to PRA RAI 16.01 a) There are no other uncredited systems in the FPRA that are associated with a VFDR.
Therefore, the uncredited systems in the FPRA do not impact the transition change in risk.
b) See part a.
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