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Category:Letter type:DCL
MONTHYEARDCL-24-010, Nuclear Material Transaction Report for New Fuel2024-01-29029 January 2024 Nuclear Material Transaction Report for New Fuel DCL-24-009, Nuclear Material Transaction Report for New Fuel2024-01-17017 January 2024 Nuclear Material Transaction Report for New Fuel DCL-24-008, Schedule Considerations for Review of the DCPP License Renewal Application2024-01-17017 January 2024 Schedule Considerations for Review of the DCPP License Renewal Application DCL-24-004, Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2024-01-15015 January 2024 Supplement to License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b DCL-23-129, Nuclear Material Transaction Report for New Fuel2023-12-27027 December 2023 Nuclear Material Transaction Report for New Fuel DCL-23-122, Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation2023-12-14014 December 2023 Request for Exemption from Enhanced Weapons, Firearms Background Checks, and Security Event Notifications Implementation DCL-23-128, Emergency Plan Update2023-12-13013 December 2023 Emergency Plan Update DCL-23-125, Core Operating Limits Report for Unit 1 Cycle 252023-12-0606 December 2023 Core Operating Limits Report for Unit 1 Cycle 25 DCL-23-121, Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System2023-11-16016 November 2023 Supplement to License Amendment Request 23-03, Revision to Technical Specification3.7.8, Auxiliary Saltwater System DCL-23-120, License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System2023-11-14014 November 2023 License Amendment Request 23-03 Revision to Technical Specification 3.7.8, Auxiliary Saltwater (Asw) System DCL-23-118, License Renewal Application2023-11-0707 November 2023 License Renewal Application DCL-2023-520, Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP)2023-10-19019 October 2023 Discharge Self-Monitoring at Diablo Canyon Power Plant (DCPP) DCL-23-103, Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System2023-10-13013 October 2023 Independent Spent Fuel Storage Installation - Withdrawal of License Amendment Request 22-01, Request for Approval of Alternative Security Measures for Early Warning System DCL-23-092, Material Status Report for the Period Ending August 31, 20232023-09-28028 September 2023 Material Status Report for the Period Ending August 31, 2023 DCL-23-077, License Amendment Request 23-02 Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors2023-09-27027 September 2023 License Amendment Request 23-02 Application to Adopt 10 CFR 50.69, Risk-Informed Categorization and Treatment of Structures, Systems and Components for Nuclear Power Reactors DCL-23-083, Upcoming Meeting with Nuclear Security and Incident Response Staff2023-09-13013 September 2023 Upcoming Meeting with Nuclear Security and Incident Response Staff DCL-23-078, Nuclear Material Transaction Report for New Fuel2023-09-0606 September 2023 Nuclear Material Transaction Report for New Fuel DCL-23-070, Withdrawal of Request Regarding Senior Reactor Operator License Application2023-08-16016 August 2023 Withdrawal of Request Regarding Senior Reactor Operator License Application DCL-23-068, Nuclear Material Transaction Report for New Fuel2023-08-0909 August 2023 Nuclear Material Transaction Report for New Fuel DCL-23-066, Nuclear Material Transaction Report for New Fuel2023-08-0303 August 2023 Nuclear Material Transaction Report for New Fuel DCL-23-065, Letter DCL-23-065 Request That Exam Material Be Withheld from Public Disclosure2023-07-27027 July 2023 Letter DCL-23-065 Request That Exam Material Be Withheld from Public Disclosure DCL-23-064, Nuclear Material Transaction Report for New Fuel2023-07-26026 July 2023 Nuclear Material Transaction Report for New Fuel DCL-23-054, License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b2023-07-13013 July 2023 License Amendment Request 23-01 Revision to Technical Specifications to Adopt Risk-Informed Completion Times TSTF-505, Revision 2, Provide Risk-Informed Extended Completion Times - RITSTF Initiative 4b DCL-23-055, Nuclear Material Transaction Report for New Fuel2023-07-0606 July 2023 Nuclear Material Transaction Report for New Fuel DCL-23-042, Independent Spent Fuel Storage Installation, Submittal of Quality Assurance Program Description, Revision 02023-05-24024 May 2023 Independent Spent Fuel Storage Installation, Submittal of Quality Assurance Program Description, Revision 0 DCL-23-032, Independent Spent Fuel Storage Installation Docket No. 72-27, Materials License Number SNM-2514 Humboldt Bay Independent Spent Fuel Storage Installation - NRC Requested Notification of Withdrawal from Voluntary Program2023-05-22022 May 2023 Independent Spent Fuel Storage Installation Docket No. 72-27, Materials License Number SNM-2514 Humboldt Bay Independent Spent Fuel Storage Installation - NRC Requested Notification of Withdrawal from Voluntary Program DCL-23-041, 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 20222023-05-22022 May 2023 10 CFR 50.46 Annual Report of Emergency Core Cooling System Evaluation Model Changes for Peak Cladding Temperature for 2022 DCL-23-038, Revision to the Unit 1 Reactor Vessel Material Surveillance Program Withdrawal Schedule2023-05-15015 May 2023 Revision to the Unit 1 Reactor Vessel Material Surveillance Program Withdrawal Schedule DCL-23-034, 2022 Annual Nonradiological Environmental Operating Report2023-05-0101 May 2023 2022 Annual Nonradiological Environmental Operating Report DCL-23-036, 2022 Annual Radiological Environmental Operating Report2023-05-0101 May 2023 2022 Annual Radiological Environmental Operating Report DCL-23-025, 2022 Annual Radioactive Effluent Release Report2023-05-0101 May 2023 2022 Annual Radioactive Effluent Release Report DCL-2023-512, Submittal of Receiving Water Monitoring Program 2022 Annual Report2023-04-27027 April 2023 Submittal of Receiving Water Monitoring Program 2022 Annual Report DCL-23-035, Response to Request for Additional Information on Request Regarding Senior Reactor Operator License Application2023-04-24024 April 2023 Response to Request for Additional Information on Request Regarding Senior Reactor Operator License Application DCL-23-028, Technical Specification Bases, Revision 142023-04-24024 April 2023 Technical Specification Bases, Revision 14 DCL-2023-511, Report on Discharge Monitoring for the First Quarter of 20232023-04-20020 April 2023 Report on Discharge Monitoring for the First Quarter of 2023 DCL-23-031, Submittal of Annual Report of Occupational Radiation Exposure for 20222023-04-19019 April 2023 Submittal of Annual Report of Occupational Radiation Exposure for 2022 DCL-23-024, Independent Spent Fuel Storage Installation, Response to Nrg Request for Additional Information for Revision to License Amendment Request 22-01 Request for Approval of Alternative Security Measures for Early Warning System2023-04-0404 April 2023 Independent Spent Fuel Storage Installation, Response to Nrg Request for Additional Information for Revision to License Amendment Request 22-01 Request for Approval of Alternative Security Measures for Early Warning System DCL-23-022, 2023 Annual Statement of Insurance for Pacific Gas and Electric Companys Diablo Canyon Power Plant2023-03-29029 March 2023 2023 Annual Statement of Insurance for Pacific Gas and Electric Companys Diablo Canyon Power Plant DCL-23-023, Decommissioning Funding Report for Diablo Canyon Power Plant, Units 1 and 22023-03-28028 March 2023 Decommissioning Funding Report for Diablo Canyon Power Plant, Units 1 and 2 DCL-23-021, Independent Spent Fuel Storage Installation, Emergency Plan Update2023-03-23023 March 2023 Independent Spent Fuel Storage Installation, Emergency Plan Update DCL-23-020, Responses to NRC Questions Regarding License Renewal Efforts2023-03-17017 March 2023 Responses to NRC Questions Regarding License Renewal Efforts DCL-23-009, Owner'S Activity Report for Unit 2 Twenty-Third Refueling Outage2023-02-22022 February 2023 Owner'S Activity Report for Unit 2 Twenty-Third Refueling Outage DCL-23-008, Request Regarding Senior Reactor Operator License Application2023-02-22022 February 2023 Request Regarding Senior Reactor Operator License Application DCL-2023-503, Annual Sea Turtle Report2023-01-26026 January 2023 Annual Sea Turtle Report DCL-2023-502, (DCPP) 4th Quarter 2022 Report on Discharge Self-Monitoring2023-01-18018 January 2023 (DCPP) 4th Quarter 2022 Report on Discharge Self-Monitoring DCL-22-091, Revised Steam Generator Tube Inspection Report for Twenty-First Refueling Outage2022-12-20020 December 2022 Revised Steam Generator Tube Inspection Report for Twenty-First Refueling Outage DCL-22-089, Core Operating Limits Report for Unit 2 Cycle 242022-12-20020 December 2022 Core Operating Limits Report for Unit 2 Cycle 24 DCL-22-085, Request to Resume Review of the License Renewal Application or, Alternatively, for an Exemption from 10 CFR 2.109(b), Concerning a Timely Renewal Application2022-10-31031 October 2022 Request to Resume Review of the License Renewal Application or, Alternatively, for an Exemption from 10 CFR 2.109(b), Concerning a Timely Renewal Application DCL-22-041, Site-Specific Decommissioning Cost Estimate, Revision 12022-10-12012 October 2022 Site-Specific Decommissioning Cost Estimate, Revision 1 DCL-22-042, Post-Shutdown Decommissioning Activities Report, Revision 12022-10-12012 October 2022 Post-Shutdown Decommissioning Activities Report, Revision 1 2024-01-29
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Pacific Gas and Electric Company Donna Jacobs Diablo Canyon Power Plant Vice President P. 0. Box 56 Nuclear Services Avila Beach, CA 93424 805.545.4600 January 31, 2007 Fax: 805.545.4234 PG&E Letter DCL-07-007 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 Diablo Canyon Units 1 and 2 Response to NRC Request for Additional Information Regarding NRC Generic Letter 2006-02, "Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power"
References:
- 1. NRC Generic Letter 2006-02, "Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power," dated February 1,2006
- 2. PG&E Letter DCL-06-042, "60-Day Response to NRC Generic Letter 2006-02, 'Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power,"' dated March 31, 2006
- 3. NRC Letter, "Request for Additional Information Regarding Resolution of Generic Letter 2006-02, Grid Reliability and the Impact of Plant Risk and the Operability of Offsite Power (TAC Nos. MD0947 through MD1050)," dated December 5, 2006
Dear Commissioners and Staff:
Generic Letter (GL) 2006-02, "Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power," (Reference 1) requested licensees to determine if compliance is being maintained with NRC regulatory requirements governing electric power sources and associated personnel training. Pacific Gas and Electric Company (PG&E) responded to GL 2006-02 in Reference 2.
In Reference 3, the NRC staff requested additional information required to resolve GL 2006-02 issues, and indicated Questions 3 and 5 are applicable to Diablo Canyon Power Plant, Units 1 and 2. PG&E's responses to the staff's Questions 3 and 5 are provided in the Enclosure.
PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.
This letter includes no revisions to existing regulatory commitments.
A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway e Comanche Peak
F!E Document Control Desk January 31, 2007 Page 2 PG&E Letter DCL-07-007 If you have any questions, or require additional information, please contact Stan Ketelsen at (805) 545-4720.
I state under penalty of perjury that the foregoing is true and correct.
Executed on January 31, 2007.
Sincerely, Donn acobs Vice Pr ident - Nuclear Services kjs/4328 Enclosure cc: Edgar Bailey, DHS Bruce S. Mallett Terry W. Jackson Diablo Distribution cc/enc Alan B. Wang A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway
- Comanche Peak e Diablo Canyon
Enclosure PG&E Letter DCL-07-007 Response to NRC Request for Additional Information Regarding Generic Letter 2006-02, "Grid Reliability and the Impact on Plant Risk and the Operability of Offsite Power" NRC Question 3:
Verification of RTCA PredictedPost-Trip Voltage Your response to question 2(g) indicates that you have not verified by procedure the voltages predictedby the online grid analysis tool (software program) with actual real plant trip voltage values. It is important that the programs used for predictingpost-trip voltage be verified to be reasonablyaccurate and conservative. What is the range of accuracy for your [Grid Operator's]GO's contingency analysis program? Why are you confident that the post-trip voltages calculated by the GO's contingency analysis program (thatyou are using to determine operabilityof the offsite power system) are reasonablyaccurate and conservative? What is your standardof acceptance?
PG&E Response:
Generic Letter 2006-02 used the term "Transmission System Operator" (TSO) throughout the letter. The term TSO was defined to denote various entities associated with preserving the reliability of the local transmission system; however, the term "Grid Operator" (GO) was not included among them. For the purpose of this response, it is assumed that GO is included within the original TSO definition. As originally stated in the response to Generic Letter 2006-02 question 1(a), Diablo Canyon Power Plant (DCPP) Units 1 and 2 primarily communicates with the Electric System Operations (ESO) Department of the Energy Delivery division of the Pacific Gas and Electric Company (PG&E) regarding offsite power.
As stated in the response to Generic Letter 2006-02 questions 2(a) and 2(g), the ESO analysis tool is based on periodic bounding transmission studies versus an online software program. The direct comparison of actual post trip voltages to analysis results is not practical because DCPP unit trips are very infrequent compared to grid model updates and the grid operating conditions at the time of a trip are not as severe as the worst case conditions analyzed. During an August 2005 Strategic Teaming and Resource Sharing Alliance and Institute of Nuclear Power Operations assessment of switchyards, large transformers, and grid reliability, several recommendations were made. Two of these recommendations focused on the sensitivity associated with the grid related parameters used in the offsite power analysis. A sensitivity study was performed to address reasonable variations in DCPP grid preloading, total grid load, and local grid load distribution. It was concluded that the load values in the offsite power analysis are adequate for the intended purpose because the DCPP switchyard is relatively insensitive to minor variations.
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Enclosure PG&E Letter DCL-07-007 NRC Question 5:
Seasonal Variationin Grid Stress (Reliability and Loss-of-offsite Power (LOOP)
Probability)
Certainregions during certain times of the year (seasonalvariations)experience higher grid stress as is indicated in Electric Power Research Institute (EPRI) Report 1011759, Table 4-7, Grid LOOP Adjustment Factor,and NRC NUREG/CR-6890. Do you adjust the base LOOP frequency in your probabilisticrisk assessment (PRA) and Maintenance Rule evaluations for various seasons? If you do not considerseasonal variations in base LOOP frequency in your [probabilisticrisk assessment] PRA and Maintenance Rule evaluations, explain why it is acceptablenot to do so.
PG&E Response:
The estimates for LOOP initiating event frequencies used in the DCPP PRA model are not adjusted for seasonal variation. These LOOP estimates are based on the latest NRC data from draft NUREG/CR (INEEL/EXT-04-02326), "Evaluation of Loss of Offsite Power Events at Nuclear Plants: 1986-2003 (Draft)", October 2004, and represent an averaged yearly LOOP frequency for grid, severe weather, plant-centered, and switchyard-related LOOP events. This NRC data is further updated by using plant specific data.
PG&E believes that the use of average LOOP frequencies provides better overall insight than using a higher-than-average estimate for certain seasons and a lower-than-average frequency for others. The use of different LOOP frequencies for different seasons could result in either an underestimation of risk (if LOOP frequency were to be decreased for certain seasons to maintain a correct average LOOP frequency) or mask the risk contribution from other plant configurations (if LOOP frequency was increased).
Currently, 10 CFR 50.65(a)(4) Maintenance Rule evaluations use a yearly average for LOOP frequency to provide a quantitative measure of risk. These evaluations account for actual grid conditions by qualitatively considering external trip risks or grid conditions. For example, plant risk status is elevated for California Independent System Operator Stage 3 Alerts, controlled fires near transmission lines, or miscellaneous grid risks. Such emergent external risk conditions are addressed by implementing the appropriate compensatory measures.
Although PG&E believes that using an average LOOP frequency for 10 CFR 50.65(a)(4) evaluations provides better overall risk insights year round, DCPP plans on implementing Safety Monitor. Safety Monitor is an enhanced on-line risk assessment tool that has the ability to adjust initiator frequencies according to emergent external conditions. Safety Monitor users (e.g., operations, scheduling, and PRA engineering personnel) will be able to perform sensitivity analyses, if appropriate, for 2
Enclosure PG&E Letter DCL-07-007 emerging or predicted conditions, including the conditions mentioned above, by increasing LOOP frequency and performing a quantitative risk assessment.
The intent of the 10 CFR 50.65(a)(4) evaluation is to obtain risk insights based on the best available information and, if necessary implement risk-reducing measures. PG&E believes that the current approach of combined quantitative and qualitative risk assessment is adequate to meet the intent of the required 10 CFR 50.65(a)(4) risk assessment. Additionally, the planned move to Safety Monitor, an enhanced on-line risk assessment tool, will further increase the ability to perform realistic assessments of maintenance-related activities.
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