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| | issue date = 06/21/2007 | | | issue date = 06/21/2007 |
| | title = 6/21/07 E-Mail from M. Thadani, Nrr/Dorl/Lpliv, to F. Madden and T. Hope, Txu Power - Request for Additional Information on License Amendment Request on Extension of Completion Times (MD4066, MD4067) | | | title = 6/21/07 E-Mail from M. Thadani, Nrr/Dorl/Lpliv, to F. Madden and T. Hope, Txu Power - Request for Additional Information on License Amendment Request on Extension of Completion Times (MD4066, MD4067) |
| | author name = Thadani M C | | | author name = Thadani M |
| | author affiliation = NRC/NRR/ADRO/DORL/LPLIV | | | author affiliation = NRC/NRR/ADRO/DORL/LPLIV |
| | addressee name = Hope T, Madden F | | | addressee name = Hope T, Madden F |
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MONTHYEARCPSES-200700130, License Amendment Request (LAR) 06-009, Revision to Technical Specification (TS) 3.8.1, AC Sources - Operating, Extension of Completion Times for Diesel Generators2007-01-18018 January 2007 License Amendment Request (LAR) 06-009, Revision to Technical Specification (TS) 3.8.1, AC Sources - Operating, Extension of Completion Times for Diesel Generators Project stage: Request ML0717700432007-06-21021 June 2007 6/21/07 E-Mail from M. Thadani, Nrr/Dorl/Lpliv, to F. Madden and T. Hope, Txu Power - Request for Additional Information on License Amendment Request on Extension of Completion Times (MD4066, MD4067) Project stage: RAI ML0720703872007-07-25025 July 2007 (E-MAIL) RAI Information Revision of TS 3.8.1, AC Sources-Operating Extension of Completion Times for Diesel Generators Project stage: RAI CP-200800183, Withdrawal of License Amendment Request (LAR) 06-009, Revision to Technical Specification 3.8.1, AC Sources - Operating, Extension of Completion Times for Diesel Generators2008-01-30030 January 2008 Withdrawal of License Amendment Request (LAR) 06-009, Revision to Technical Specification 3.8.1, AC Sources - Operating, Extension of Completion Times for Diesel Generators Project stage: Withdrawal ML0812904622008-05-21021 May 2008 Withdrawal of License Amendment Request 06-009 to Revise Technical Specification 3.8.1, AC Sources - Operating, Extension of Completion Times for Diesel Generators Project stage: Withdrawal 2007-07-25
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Category:E-Mail
MONTHYEARML24025A0172024-01-22022 January 2024 NRC Request for Concurrence with Endangered Species Act Determinations for Comanche Peak License Renewal, Issuance of Draft Supplemental Environmental Impact Statement, and Opportunity for Public Comment ML24019A0742024-01-19019 January 2024 NRR E-mail Capture - Comanche Peak - Draft Request for Additional Information - License Amendment Request to Extend the Allowed Outage Time for an Inoperable Emergency Diesel Generator ML24008A2492023-12-18018 December 2023 Texas Shpo Response for Comanche Peak Deis Review and Comment ML23311A2202023-11-20020 November 2023 NRC to Fws, NRC Request for Concurrence with Endangered Species Act Determinations for Comanche Peak License Renewal, Issuance of Draft Supplemental Environmental Impact Statement, and Opportunity for Public Comment (Consultation Code: 2023 ML23255A2882023-09-12012 September 2023 NRR E-mail Capture - Comanche Peak - Acceptance of Request for Exemption from 10 CFR 50.71(e)(4) Final Safety Analysis Update Schedule ML23256A1492023-09-11011 September 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 4 ML23226A0072023-08-11011 August 2023 NRR E-mail Capture - Comanche Peak 1 and 2 Audit Plan - License Amendment Request to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors ML23188A0442023-07-0707 July 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 3 ML23181A0722023-06-29029 June 2023 NRR E-mail Capture - Comanche Peak - Acceptance of License Amendment Request to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors ML23181A0202023-06-29029 June 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 2 ML23172A0152023-06-20020 June 2023 NRR E-mail Capture - Re Comanche Peak - Acceptance of License Amendment Request Regarding General Design Criterion 5 of Appendix a to 10 CFR Part 50 and Regulatory Guide 1.81 ML23167A0222023-06-14014 June 2023 Email: Request for Additional Information (RAI) Letter for the Review of the Comanche Peak Initial License Renewal Application, Set 1 ML23145A2332023-05-25025 May 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Confirmation of Information - Set 2 ML23143A1382023-05-23023 May 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Confirmation of Information - Set 1 ML23139A0802023-05-18018 May 2023 NRR E-mail Capture - Comanche Peak Draft Supplemental Information Request - License Amendment Request Regarding General Design Criterion 5 of Appendix a to 10 CFR Part 50 and Regulatory Guide 1.81 ML23138A1522023-05-18018 May 2023 Lr Docs - (External_Sender) Comanche Peak Nuclear Power Plants ML23135A9132023-05-15015 May 2023 NRR E-mail Capture - Comanche Peak - Draft Supplemental Information Request - License Amendment Request to 10 CFR 50.69 ML23131A2932023-05-11011 May 2023 Lr Docs - License Renewal for Comanche Peak Nuclear Power Plant, Units 1 and 2 ML23128A1612023-05-0808 May 2023 NRR E-mail Capture - Comanche Peak Nuclear Power Plant, Units 1 and 2, Beaver Valley Power Station, Unit Nos. 1 and 2, Davis-Besse Nuclear Power Station, Unit 1, and Perry Nuclear Power Plant, Unit No. 1 - Acceptance of Requested Licensing ML23110A7122023-04-20020 April 2023 NRR E-mail Capture - Comanche Peak - Verbal Authorization of Proposed Alternative RV-1 (L-2023-LLR-0019) ML23103A4682023-04-11011 April 2023 NRR E-mail Capture - Comanche Peak Request for Additional Information - License Amendment Request to Apply the Westinghouse Full Spectrum Loss of Coolant Accident Evaluation Model ML23086B9852023-03-27027 March 2023 NRR E-mail Capture - Comanche Peak Draft Request for Additional Information - Request to Apply the Westinghouse Full Spectrum Loss of Coolant Accident Evaluation Model ML23061A1612023-03-0202 March 2023 E-mail from David Griggs Regarding Submission to NRC Electronic Information Exchange on 03/01/2023 for Citizens for Fair Utility Regulation in Comanche Peak Proceeding ML23032A3842023-02-0101 February 2023 LRA On-Site Audit Needs List ML23214A0192023-01-30030 January 2023 (External_Sender) Request to Broaden Extended Deadline to the General Public (with Attachments) - C3 ML23214A0202023-01-29029 January 2023 (External_Sender) Requesting a Deadline Extension on NRC-2002-0183, Comanche Peak License Renewal - C2 ML23214A0182023-01-26026 January 2023 (External Sender) NRC-2022-0183-0003 (with Attachment) - C6 ML23214A0162023-01-24024 January 2023 (External Sender) EPA Scoping Comment Letter for the Comanche Peak Nuclear Power Plant License Renewal (with Attachment) - C8 ML23214A0142023-01-23023 January 2023 (External Sender) Docket NRC-2022-0183 Comanche Peak Nuclear Power Plant Renewal (with Attachment) - C1 ML23214A0172023-01-17017 January 2023 (External Sender) NRC License Extension? No! ML23214A0132023-01-17017 January 2023 (External Sender) Docket Id NRC-2022-0183, Request for Extension of License for Comanche Peak, Comment for Environmental Scoping - C9 ML23214A0122023-01-13013 January 2023 (External Sender) Correction to Comment Submitted 01-13-23 - C11 ML22362A0992022-12-28028 December 2022 NRR E-mail Capture - Comanche Peak - Acceptance of License Amendment Request to Apply Westinghouse Fsloca Evaluation Model ML22362A0972022-12-28028 December 2022 NRR E-mail Capture - Comanche Peak - Acceptance of License Amendment Request to Adopt WCAP-17661-P-A, Revision 1, Improved RAOC and CAOC Fq Surveillance Technical Specifications, ML22325A2742022-11-21021 November 2022 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Proposed Alternative P-1 Regarding IST of Safeguards Building Sump Pumps ML22318A3102022-11-10010 November 2022 NRR E-mail Capture - Comanche Peak - Draft Request for Additional Information - Proposed Alternative P-1 Regarding IST of Safeguards Building Sump Pumps ML22237A2842022-08-25025 August 2022 CPNPP 2022 EP Program Inspection RFI Hjs 08252022 ML22230B1092022-08-17017 August 2022 NRR E-mail Capture - Comanche Peak Unit 2 - Request for Additional Information - 2RE19 Inspection Summary Report for Steam Generator Tubing ML22229A0792022-08-17017 August 2022 NRR E-mail Capture - Comanche Peak - Acceptance of Requested Licensing Action - Proposed Alternative P-1 Regarding IST of Safeguards Building Sump Pumps ML22220A1942022-08-0808 August 2022 NRR E-mail Capture - Comanche Peak Unit 2 - Draft Request for Additional Information - 2RE19 Inspection Summary Report for Steam Generator Tubing ML22133A0472022-05-13013 May 2022 July 2022 Emergency Preparedness Exercise Inspection - Request for Information ML22083A0262022-03-23023 March 2022 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Request to Adopt TSTF 505 Revision 2 ML22031A2122022-01-31031 January 2022 NRR E-mail Capture - Comanche Peak - Acceptance of Requested Licensing Action - Proposed Alternative to Extend the Snubber Inservice Program Third Interval ML21300A1342021-10-27027 October 2021 NRR E-mail Capture - Comanche Peak Units 1 and 2 - License Amendment Request to Adopt TSTF-505 - Audit Plan Update and Audit Questions (L-2021-LLA-0085) ML21286A7912021-10-13013 October 2021 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Request to Adopt TSTF-577 Revision 1 ML21272A2002021-09-29029 September 2021 NRR E-mail Capture - Comanche Peak Unit 2 - Upcoming Steam Generator Tube Inservice Inspection (L-2021-NFO-0013) ML21270A1632021-09-27027 September 2021 NRR E-mail Capture - Comanche Peak - Acceptance of Quality Assurance Program Change Request Regarding Internal Audit Frequency ML21253A2242021-09-0909 September 2021 Request for Information Occupational Radiation Safety Inspection (71124.01, 71124.02, and 71151) from 10/18-22/2021 ML21252A0062021-08-26026 August 2021 NRR E-mail Capture - Comanche Peak - Acceptance of License Amendment Request Regarding Adoption of TSTF-577, Revised Frequencies for Steam Generator Tube Inspections 2024-01-22
[Table view] Category:Request for Additional Information (RAI)
MONTHYEARML24019A0742024-01-19019 January 2024 NRR E-mail Capture - Comanche Peak - Draft Request for Additional Information - License Amendment Request to Extend the Allowed Outage Time for an Inoperable Emergency Diesel Generator ML24018A1072024-01-18018 January 2024 Notification of Commercial Grade Dedication Inspection (05000445/2024012 and 05000446/2024012) and Request for Information ML23256A1502023-09-11011 September 2023 Request for Additional Information Requests - Comanche Peak - Set 4 ML23256A1492023-09-11011 September 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 4 ML23213A2162023-08-0202 August 2023 Vistra Operations Company, LLC Notification of License Renewal Inspection and Request for Information ML23188A0452023-07-0707 July 2023 Request for Additional Information Requests - Comanche Peak - Set 3 ML23188A0442023-07-0707 July 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 3 ML23181A0212023-06-29029 June 2023 Request for Additional Information Requests - Comanche Peak - Set 2 ML23181A0202023-06-29029 June 2023 Email from Mark Yoo (NRC) to Ken Peters (Vistra) - Comanche Peak LRA - Request for Additional Information - Set 2 ML23167A0222023-06-14014 June 2023 Email: Request for Additional Information (RAI) Letter for the Review of the Comanche Peak Initial License Renewal Application, Set 1 ML23167A0232023-06-14014 June 2023 Request for Additional Information (RAI) for the Review of the Comanche Peak Initial License Renewal Application (Lra), Set 1 ML23145A2322023-05-25025 May 2023 LRA - Request for Confirmation of Information - Set 2 ML23143A1372023-05-23023 May 2023 LRA - Request for Confirmation of Information - Set 1 ML23132A2542023-05-23023 May 2023 Supplemental Information Needed for Acceptance of Requested Licensing Action LAR to Adopt 10 CFR 50.69,Risk-Informed Categorization & Treatment of Structures,Systems & Components for Nuclear Power Reactors EPID L-2023-LLA-0057 ML23068A0562023-05-0909 May 2023 Request for Additional Information - Comanche Peak License Renewal Application Environmental Review ML23068A0732023-04-13013 April 2023 Requests for Confirmation of Information for the Environmental Review of the Comanche Peak Nuclear Power Plant, Units 1 and 2, Licensed Renewal Application (EPID Number: L-2022-LNE-0004) (Docket Numbers 50-445 and 50-446) ML23103A4682023-04-11011 April 2023 NRR E-mail Capture - Comanche Peak Request for Additional Information - License Amendment Request to Apply the Westinghouse Full Spectrum Loss of Coolant Accident Evaluation Model ML23086B9852023-03-27027 March 2023 NRR E-mail Capture - Comanche Peak Draft Request for Additional Information - Request to Apply the Westinghouse Full Spectrum Loss of Coolant Accident Evaluation Model ML23010A1442023-01-0909 January 2023 Inservice Inspection Request for Information ML22325A2742022-11-21021 November 2022 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Proposed Alternative P-1 Regarding IST of Safeguards Building Sump Pumps ML22318A3102022-11-10010 November 2022 NRR E-mail Capture - Comanche Peak - Draft Request for Additional Information - Proposed Alternative P-1 Regarding IST of Safeguards Building Sump Pumps ML22230B1092022-08-17017 August 2022 NRR E-mail Capture - Comanche Peak Unit 2 - Request for Additional Information - 2RE19 Inspection Summary Report for Steam Generator Tubing ML22220A1942022-08-0808 August 2022 NRR E-mail Capture - Comanche Peak Unit 2 - Draft Request for Additional Information - 2RE19 Inspection Summary Report for Steam Generator Tubing ML22179A3032022-06-28028 June 2022 Information Request for the Cyber-Security Baseline Inspection, Notification to Perform Inspection 05000445/2022401; 05000446/2022401 ML22083A0262022-03-23023 March 2022 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Request to Adopt TSTF 505 Revision 2 ML21286A7912021-10-13013 October 2021 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Request to Adopt TSTF-577 Revision 1 ML21253A2242021-09-0909 September 2021 Request for Information Occupational Radiation Safety Inspection (71124.01, 71124.02, and 71151) from 10/18-22/2021 ML21253A2332021-09-0909 September 2021 Request for Information: Comanche Peak Nuclear Power Plant, Units 1 and 2 (05000445 and 05000446); Occupation Radiation Safety (71124.01, 71124.02, 7511) ML21245A3072021-09-0202 September 2021 Request for Information ML21245A307 ML21166A3382021-06-22022 June 2021 Supplemental Information Needed for Acceptance of Requested Licensing Action LAR to Adopt TSTF-505, Rev. 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b ML21165A1022021-06-13013 June 2021 Pi&R; Request for Information ML21103A3982021-04-13013 April 2021 CP Security Inspection Information Request 2021403 ML20225A0932020-08-12012 August 2020 Notification of Inspection 05000445/2020004 and 05000446/2020004 and Request for Information ML20105A1072020-04-13013 April 2020 NRR E-mail Capture - Comanche Peak - Request for Additional Information - Exigent Amendment Request for One Time Change to Unit 2 Steam Generator Inspection Frequency ML20104A0022020-04-11011 April 2020 NRR E-mail Capture - Comanche Peak Unit 2 - Request for Additional Information - Proposed Alternative to ASME OM Code for Deferral of Snubber Testing (SNB-1) and Visual Examinations (SNB-2) ML20045E3512020-02-13013 February 2020 Information Request February 13, 2020 Notification of Inspection and Request for Information Comanche Peak Unit 2 NRC Inspection Report 05000446/2020002 ML19346B3812019-12-11011 December 2019 NRR E-mail Capture - Comanche Peak RAIs - Quality Assurance Program Reduction in Commitment ML19319A5432019-11-14014 November 2019 NRR E-mail Capture - Draft Comanche Peak RAIs - Quality Assurance Program Reduction in Commitment ML19058A3592019-02-27027 February 2019 NRR E-mail Capture - Comanche Peak Nuclear Power Plant, Unit Nos. 1 and 2 - Final Request for Additional Information Concerning License Amendment Request to Revise the Emergency Plan IR 05000445/20170072018-02-0808 February 2018 Notification of Nrc Design Bases Assurance Inspection (Programs) (05000445/2017007 and 05000446/2017007) ML17276B8622017-10-0303 October 2017 Notification of NRC Design Bases Assurance Inspection (Programs)(05000445/2017007 and 05000446/2017007) and Initial Request for Information ML17087A2032017-03-28028 March 2017 NRR E-mail Capture - Comanche Peak, Unit 2 - Final Request for Additional Information Regarding Request No. 2B3-1 ML17066A2372017-03-0707 March 2017 Notification of NRC Triennial Fire Protection Baseline Inspection (05000445/2017008 and 05000446/2017008) and Request for Information ML17048A4172017-02-17017 February 2017 Notification of NRC Inspection of the Implementation of Mitigation Strategies and Spent Fuel Pool Instrumentation Orders and Emergency Preparedness Communication/ Staffing/Multi-Unit Dose Assessment... ML16034A1962016-02-0808 February 2016 Independent Spent Fuel Storage Installation - Request for Additional Information, Application for Order Approving Transfer of Facility Operating Licenses and Conforming Amendment ML16015A0032016-01-14014 January 2016 NRR E-mail Capture - Request for Additional Information - Relief Request 1B3-3 for Comanche Peak Nuclear Power Plant, Unit 1 ML15345A0112015-12-16016 December 2015 Request for Additional Information, License Amendment Request, Revise Emergency Action Levels Based on Nuclear Energy Institute (NEI) 99-01, Revision 6 ML15317A1582015-11-13013 November 2015 Request for Additional Information Email, Relief Request B-15, C-2, and C-4 for Welds in the RPV and Containment Spray and Residual Heat Removal Heat Exchanger Shells, Second 10-year Inservice Inspection Interval ML15317A1482015-11-13013 November 2015 Request for Additional Information Email, Relief Request No. B-9 for Reactor Pressure Vessel Outlet Nozzle Safe End to Piping Welds, Second 10-year Inservice Inspection Interval ML15317A1502015-11-13013 November 2015 Request for Additional Information Email, Relief Request No. B-3 for Reactor Coolant System Pipe to Pipe Flange Weld, Second 10-year Inservice Inspection Interval 2024-01-19
[Table view] |
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From: Mohan ThadaniTo:Internet:fred.madden@txu.com; Internet:Timothy.Hope@txu.comDate: 6/21/2007 11:16:35 AM
Subject:
Fwd: CPSES_EXTENSION EDG CTs (TAC Nos. MD4066 and MD4067) - RAIFred/Tim:
The NRC staff has reviewed your application for extension of completion times for dieselgenerators (TAC Nos. MD4066 and MD4067), and has identified a need for additional information. Early response to the following request for additional information is needed to complete our review in a timely manner. Please advise your schedule for response to this request, and indicate if you require that thisrequest be formally sent to you by a letter. Thanks.
Mohan
____________________________________________________________________________
____________
REQUEST FOR ADDITIONAL INFORMATION1.The calculations of the change in core damage frequency (DCDF) and change in largeearly release frequency (DLERF) effectively assume a single entry into the extended 14-day completion time (CT) each year, but no such restrictions have been identified and the licensee specifically states they will use the 14-day CT for corrective maintenance if needed. The licensee has identified the recent corrective maintenance history, but has not identified frequencies and durations of any proposed planned preventive maintenance which would be implemented using the extended CT. The licensee is requested to justify the assumption of one 14-day CT per year, or provide appropriate risk analyses for more realistic assumptions, or proposed appropriate restrictions on the applicability of the extended CT.2.The licensee stated with regards to the potential for common cause failure (CCF) of theremaining operable diesel generator (DG), that if a common mode failure exists, Technical Specification (TS) 3.0.3 would require the plant to be shutdown. It is not clear to the staff why TS 3.0.3 would always apply under these circumstances, since the existing TS 3.8.1 provides action requirements. The licensee is requested to clarify the TS applicability in the event of a discovery of a CCF mode affecting the DGs, including any cross-unit considerations. 3.The licensee has identified the modeling assumptions with regards to the alternate ACpower source (AACPS). The staff has additional questions regarding how the AACPS is credited in the risk analyses supporting this proposed change:a.It is not clear whether the model assumes an automatic start and load capabilityof the AACPS with manual operator backup, or whether the manual operator action is always required. Section 1.0 of Attachment 1 of the licensee submittal states that the AACPS would be started manually or automatically, and connected to the bus when it has achieved rated voltage and speed. Section 4.2.4.2 however states that no credit is taken for scenarios due to insufficient time for manual starting and loading. The licensee is requested to clarify the specific assumptions for the risk analyses with regards to starting the AACPS, connecting it to the emergency bus, and starting the required equipment, including whether actions are accomplished locally or from the control room. If local actions are required, the licensee should further discuss how human reliability for the AACPS was evaluated, including dependencies with other potential actions required by the probabilistic risk assessment (PRA) model and by Comanche Peak Steam Electrical Station (CPSES) emergency procedures for station blackout.
b.The licensee stated an assumption that the AACPS would be connected to theemergency bus within 15 minutes of detection of a loss of offsite power (LOOP), and therefore the AACPS would have the capacity required for safe shutdown. No basis was provided for the 15-minute time, and additional time to manually start required loads was not addressed. The licensee further identified that the reactor coolant pump seal loss of coolant accident (LOCA) model used in the PRA model uses Westinghouse Commercial Atomic Power (WCAP)-15603 Revision 1-A. This model assumes that a 13-minute interruption of pump seal cooling may result in the development of excessive leakage. The licensee is requested to clarify the basis for the assumption of 15 minutes to connect the AACPS and its potential impact on the assumptions of the PRA model with regards to seal LOCAs.c.It is not clear from the licensee's submittal if a specific AACPS has beenidentified, either permanent or temporary. Therefore, specific assumptions in the risk analyses regarding the reliability of the AACPS, its fuel supply, its output breaker, procedures for operation, human reliability and the associated procedural bases, are not defined. The licensee is requested to provide a basis for the assumptions regarding reliability of the AACPS as a system (including the above specific items) being equivalent to the existing DGs.d.The licensee stated that the AACPS would require a 24-hour fuel oil supply. Thisis less than the 7-day supply required by the CPSES TS 3.8.4. Typically, the PRA mission time is 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, but this assumes a safe stable end state has been achieved, which would not be the case if the AACPS did not have fuel oil beyond 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The licensee is requested to discuss the availability of additional fuel oil beyond 24-hours to support the continued use of the AACPS under emergency conditions.4.The licensee is requested to identify the specific version and date of the probabilistic riskassessment (PRA) model applied for the risk evaluations supporting the proposed change, and identify any plant changes (i.e., modifications, procedure revisions, or other items) not yet incorporated into the PRA model, including justification that such unincorporated changes do not adversely impact the stated risk impact.5.The licensee stated that the computation of incremental conditional core damageprobability (ICCDP) and incremental conditional large early release probability (ICLERP) were per the definitions in Regulatory Guide (RG) 1.177, and identified specific equations used to perform the calculations. However, RG 1.177 uses the increase above the nominal baseline risk, including contributions from nominal expected equipment unavailability, while the licensee calculations specify the use of the baseline CDF without test or maintenance contributions included. The licensee is requested to clarify its calculation basis, which appears to be different than the specific RG 1.177 guidance. 6.The licensee stated that for emergent repair-type use of the extended CT, the AACPSwould be in place prior to exceeding the 72-hour CT, consistent with the TS Required Actions as proposed; however, the analyses of risk assume the availability of the AACPS throughout the 14-day CT. The licensee is requested to provide the applicable risk analyses without crediting the AACPS for the first 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> consistent with its stated intent of AACPS availability to support emergent repairs.7.The licensee's qualitative evaluation of external events including internal fires and floodsconsiders only events which may cause a LOOP but which specifically do not impact the DGsor their support systems. The staff does not agree with this approach, since there may be internal flooding or fire scenarios which can cause a LOOP and also affect one of the two safety trains, which would be potentially significant for this application. The licensee is requested toidentify whether there are such scenarios possible given the physical layout and separation of the offsite power circuits with regards to internal fires and floods, and if necessary provide additional analyses to disposition these scenarios.8.A seismically-induced LOOP frequency of 5E-5 per year was demonstrated andcompared to the nominal LOOP frequency of 3.49E-2 per year to conclude that the additional risk from seismic events was small. However, for this application, the non-seismic LOOPevents can be mitigated by the AACPS which would not be available after a seismic event.
Further, recovery of offsite power following a seismic event is not likely until some significant time after the event. The licensee is requested to provide additional evaluation of the conditional core damage probability given a seismically -induced LOOP, with no credit for offsite power recovery, no credit for AACPS, and one DG unavailable over the 14-day extended CT, to provide a more conclusive argument for low risk of seismic events.9.The licensee identified insights from the CPSES Fire PRA with regards to scenarioswhich cause a LOOP. The staff has additional questions regarding these events:a.The licensee had previously stated that it only had an internal events PRAmodel; it is not clear to what the "CPSES Fire PRA" refers.b.Three control room cabinet fires were identified as causing a LOOP but nofurther details were provided. The licensee should discuss: 1) the frequency of occurrence of these events (identified only as "very low"), 2) mitigation of these events, and 3) the capability to restore offsite power given the expected fire damage.10.The licensee's analysis of high wind events stated that such events which cause aLOOP are already included in the internal event PRA model LOOP initiating event frequency.
However, the licensee stated that the AACPS is not protected from natural phenomena or abnormal environmental or dynamic effects. Therefore, the availability of the AACPS is not assured by the licensee for these types of LOOP events. The licensee is requested to provide additional justification that the risk of such events is not significant for this application.11.The licensee's analysis of tornado events identifies a strike frequency of 5E-4 per year,and identifies that the risk exposure over the 11 additional days of the extended CT is very small. The licensee then states that "offsite power non-recovery probability is very small beyond 3 days." The staff does not understand the significance of the 3-day period identified.
As previously noted by the staff for these types of events, offsite power recovery may be significantly delayed due to the damage incurred, and a simple comparison with the nominal LOOP frequency is an inadequate justification that the risk impact is small. Further, as noted in RAI 10, the AACPS is not protected from natural phenomena and therefore may be unavailable to mitigate the impact of a tornado. The licensee is requested to provide additional justification that this external event is not a significant risk contributor.12.The licensee's analysis of internal floods stated that these events contribute "less than1% of the internal events risk". The licensee had previously stated that it only had an internal events PRA model which did not include contributions from internal floods. The licensee is requested to discuss the basis for this quantitative assessment of risk.13.The licensee's submittal did not identify if the risk analyses provided point estimates ofthe mean or actual means, nor was there any discussion of uncertainty analyses to support the calculations. The licensee is requested to address PRA model and parametric uncertainty using the guidance of RG 1.174 Section 2.2.5.14.Section 4.1 of the licensee's submittal identifies administrative controls which would beapplicable during the extended CT. In addition, Section 4.2.3 identifies plant equipment and activities which, if unavailable simultaneous with the DG, would likely result in a high risk configuration. The staff has additional questions regarding these portions of the submittal:a.The licensee's submittal does not specifically identify whether these statementsrepresent commitments. The staff notes that the licensee's risk analysis assumes no other testing or maintenance activities on other plant equipment. The licensee is requested to clarify their intent with regards to the RG 1.177 tier two portion of their request.
b.The staff notes that the section 4.1 administrative controls items 2 and 3 areworded subtly different; specifically, "weather conditions must be conducive to perform planned maintenance," and "offsite power supply and switchyard conditions must be conducive to perform maintenance". The licensee is requested to clarify the intent, if any, of the use and omission of the word "planned."c.Section 4.1 states "switchyard access will be monitored and controlled," anddiscusses the procedure STA-629. It is not clear that this represents any unique administrative control, since switchyard access should normally be so monitored and controlled using approved plant procedures. The licensee is requested to clarify the intent of this administrative control as regards its representing a unique additional restriction on switchyard activities.d.Section 4.2.3 does not explicitly identify that the potential high risk configurationswould be prohibited, consistent with the assumptions of the risk analysis, during the extended CT. In fact, the submittal states that Tier 3 risk management actions will address the availability of these systems. The licensee is requested to clarify the intent of identifying these configurations in the tier 2 section of their submittal, and identify any associated commitments consistent with RG 1.177 for tier 2.15.RG 1.177 Section 2.3.7 describes various attributes of contemporaneous configurationcontrol and the CRMP which can support risk-informed decisionmaking. Certain aspects of the licensee's program have not been adequately described to assure that the guidance of RG 1.177 is met. Specifically, the licensee only states that added or emergent activities, or activities which have slipped from the scheduled completion time, are "addressed." RG 1.77 Section 2.3.7.1 requires specific descriptions to be provided, as to their capability to perform contemporaneous assessment of overall plant safety impact of proposed plant configurations, how the tools or other processes are used to ensure risk-significant configurations are not entered, and that appropriate actions will be taken when unforseen events put the plant in a risk-significant configuration. Further, it identifies four key components of the CRMP, which have not been addressed by the licensee. The licensee is requested to confirm and describe how their CRMP conforms to the RG 1.177 Section 2.3.7 guidance.16.The licensee has submitted a proposed change to extend the CT for LCO 3.8.1 withregards to one inoperable offsite circuit from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 30 days. The staff requests clarification of certain aspects of the proposed change which may impact the proposed changes for the DGs.a.The second CT of LCO 3.8.1 applicable to contiguous application of the actionsof the TS 3.8.1 is proposed to be increased from 6 days to 17days in this amendment request, and from 6 days to 33 days for the offsite circuit request. The licensee is requested to identify the proposed final CT. The staff also notes that TSTF-439-A eliminated this second CT, and the licensee may want to consider implementation of this TSTF along with these amendment requests.b.Because these two requests are directly related to AC power sources, the staffconsiders them to be a combined change request as defined by RG 1.174 Sections 2.1.1 and 2.1.2. The licensee is requested to submit the additional information identified in RG 1.174 with regards to the synergistic impacts of the proposed changes.
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Fwd: CPSES_EXTENSION EDG CTs (TAC Nos. MD4066 and MD4067) - RAI Creation Date6/21/2007 11:16:35 AMFrom: Mohan ThadaniCreated By:MCT@nrc.gov Recipientsfred madden (Internet:fred.madden@txu.com)Timothy Hope (Internet:Timothy.Hope@txu.com)Post OfficeRoutefredInternet:txu.comTimothyInternet:txu.comFilesSizeDate & Time MESSAGE196506/21/2007 11:16:34 AMOptions Expiration Date:
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