ML24337A122
| ML24337A122 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 12/10/2024 |
| From: | John Lamb Plant Licensing Branch II |
| To: | Coleman J Southern Nuclear Operating Co |
| References | |
| EPID L-2024-LLA-0031 | |
| Download: ML24337A122 (14) | |
Text
December 10, 2024 Jamie M. Coleman Regulatory Affairs Director Southern Nuclear Operating Co., Inc.
3535 Colonnade Parkway Birmingham, AL 35243
SUBJECT:
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 - AUDIT
SUMMARY
REPORT FOR THE LICENSE AMENDMENT REQUEST TO REVISE EMERGENCY DIESEL GENERATOR FREQUENCY AND VOLTAGE RANGES FOR TECHNICAL SPECIFICATION 3.8.1, AC [ALTERNATING CURRENT] SOURCES - OPERATING, SURVEILLANCE REQUIREMENTS (EPID L-2024-LLA-0031)
Dear Jamie Coleman:
By letter dated March 20, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24080A455), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposed LAR would revise the emergency diesel generator (EDG) frequency and voltage acceptance criteria for Technical Specification (TS) 3.8.1, AC Sources -
Operating, Surveillance Requirements (SRs). The proposed LAR is required to correct a non-conservative TS.
By letter dated June 5, 2024 (ML24155A177), as supplemented by letter dated July 1, 2024 (ML24176A163), the NRC staff issued the Audit Plan.
On August 1 and 28, November 8, and December 9, 2024, the NRC staff conducted an audit in accordance with the Audit Plan. By letter dated September 9, 2024 (ML24250A204), the NRC staff extended the audit from October 31, 2024, to December 31, 2024.
Attached is the Audit Summary Report.
J. Coleman If you have any questions, please contact me at 301-415-3100.
Sincerely,
/RA/
John G. Lamb, Senior Project Manager Plant Licensing Branch II-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-424 and 50-425
Enclosure:
Audit Report cc: Listserv
Enclosure AUDIT
SUMMARY
REPORT BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR THE LICENSE AMENDMENT REQUEST TO REVISE EMERGENCY DIESEL GENERATOR FREQUENCY AND VOLTAGE RANGES FOR TECHNICAL SPECIFICATION 3.8.1, AC [ALTERNATING CURRENT] SOURCES -
OPERATING, SURVEILLANCE REQUIREMENTS (EPID L-2024-LLA-0031)
VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425
1.0 BACKGROUND
By letter dated March 20, 2024 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML24080A455), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2. The proposed LAR would revise the emergency diesel generator (EDG) frequency and voltage acceptance criteria for Technical Specification (TS) 3.8.1, AC Sources -
Operating, Surveillance Requirements (SRs). The proposed LAR is required to correct a non-conservative TS.
The NRC staff identified the need for a regulatory audit to examine the SNCs non-docketed information with the intent to gain understanding, verify information, or identify information that would be required to support the requested regulatory decision.
By letter dated September 9, 2024 (ML24250A204), the NRC staff extended the audit from October 31, 2024, to December 31, 2024. The NRC staff conducted the audit virtually via Teams using a licensee-established electronic portal available to NRC staff from approximately July 1 through December 31, 2024, with formal audit meetings scheduled during the period as needed. The NRC staff reserved the right to extend the audit, if necessary.
2.0 SCOPE AND PURPOSE By letter dated June 5, 2024 (ML24155A177), as supplemented by letter dated July 1, 2024 (ML24176A163), the NRC staff issued the audit plan to review the submitted EDG LAR for Vogtle, Units 1 and 2. On August 1 and 28, and November 8, 2024, the NRC staff conducted audit meetings in accordance with the Audit Plan.
3.0 AUDIT TEAM The audit team consisted of the following:
John G. Lamb, Division of Operating Reactor Licensing (DORL)/Plant Licensing Branch 2-1 (LPL2-1),
Khoi Nguyen, Division of Engineering and External Hazards (DEX)/Electrical Engineering Branch (EEEB),
Hadari Kodali, DEX/EEEB, Tarico Sweat, Division of Safety Systems (DSS)/Technical Specifications Branch (STSB),
Fred Forsaty, DSS/Nuclear Systems Performance Branch (SNSB),
Santosh Bhatt, DSS/SNSB, Thomas Scarbrough, DEX/Mechanical Engineering and Inservice Testing Branch (EMIB), and Michael Breach, DEX/EMIB.
4.0 AUDIT REPORT During the audit, the licensee presented information on the audit items listed in Section 4.0 of the audit plan. SNC also established an online portal and placed supporting information in the portal on each audit item. Section 5.0 of this audit report lists the documents and files the NRC staff reviewed. The NRC staff discussed with the licensee each audit item and made relevant observations contained in Attachments 1 through 3.
5.0 CONCLUSION
As a result of the audit, the NRC staff has gained a better understanding of the following:
(1) The licensees evaluation of the effects of EDG voltage and frequency variations on the performance of pumps and valves at Vogtle, Units 1 and 2, upon implementation of the LAR if approved by the NRC.
(2) All the Audit Items were resolved during the audit.
(3) No request for additional information (RAI) questions or supplemental information is needed.
In accordance with LIC-111, Revision 1, Regulatory Audits, dated October 31, 2019 (ADAMS Accession No. ML19226A274), it states:
The regulatory audit summary report should be placed on the docket and in ADAMS within 90 days of the completion of the audit or before the regulatory action that the audit supports is completed, whichever is shorter.
The audit was closed out on December 9, 2024, and the 90-day deadline for the audit summary report is March 10, 2025.
ATTACHMENT 1 AUDIT DAY 1 - AUGUST 1, 2024 Attendees NAME ORGANIZATION John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Fred Forsaty NRC Santosh Bhatt NRC Michael Markley NRC Philip Sahd NRC Ken Lowery Southern Nuclear Operating Company (SNC)
Ryan Joyce SNC Justin Martin SNC Kyle Shelton SNC The audit commenced with the above attendees. The U. S. Nuclear Regulatory Commission (NRC) staff provided background information related to how the review came to an audit.
For the duration of the audit, SNC and the NRC used Microsoft Teams and the video/audio communications of choice.
On June 14, 2024, SNC provided a link to a Certrex portal for the NRC staff to review SNC documents.
The NRC staff referred to Section 4 of the Audit Plan.
The NRC staff reviewed:
Audit Item 3 - In Section 3.0 of the LAR, SNC concluded that Motor-Operated Valve (MOV) performance is not affected by the proposed EDG voltage and frequency ranges.
Provide the following:
- a. A sample calculation for MOV performance and for other motor driven loads such as fans, pumps, heating, ventilation and air conditioning (HVAC) heaters,120 V AC etc., as applicable.
- b. A sample calculation for MOV or an evaluation, if exists, that evaluates the impact of the proposed change to the following:
MOV motor speed MOV inertia MOV voltage Pump output pressure and differential pressure on the MOV.
Audit Item 4 - Section 3 of LAR states that, The performance of the required equipment is dependent on the EDG voltage and frequency.
- a. In this Section it is stated that, review of surveillance test data over the past three years provides assurance that the revised voltage and frequency limits will be achievable. Provide evaluation for this conclusion.
- b. Provide the present Surveillance Uncertainty analysis.
- c. How the plant EDG reliability is analyzed for future extended period; for example, the next 5 fuel reload cycles?
Audit Item 5 - To reduce stress and wear on diesel engines, some manufacturers recommend that the starting speed of EDGs be limited, that warm-up be limited to a designed lower speed, and that EDGs be gradually accelerated to synchronous speed prior to loading. What are the manufacturer recommendations for the Vogtle, EDGs in support of this condition? Provide the plant procedures in support of possible EDG failure due to stress.
Audit Item 6 - Provide the analysis that evaluates the performance of the Vogtle, Units 1 and 2, containment spray pump, that generates revised minimum and maximum test curves to account for the effects of steady state EDG voltage and frequency variations, as well as evaluating flow and pressure measurement uncertainties.
Audit Item 7 - Provide the Spent Fuel Pit Pumps available margin to cover the EDG degradation uncertainty.
Audit Item 8 - Section 3.0 of the LAR discusses the emergency core cooling systems (ECCS) and Containment Spray pump evaluation. Per Section 2.1 of WCAP-17308-NP-A, the total pump head uncertainty is calculated at discrete flow rates as a function of the combined uncertainties for frequency, voltage, and various other measurements including flow and pressure.
Provide evaluation of the following ECCS pumps for the overspeed and overvoltage conditions to show sufficient margins remain to accommodate pump speed increase:
(a) Residual Heat Removal (RHR) pumps (b) Containment Spray pumps (c) Residual Heat Removal Service Water (RHRSW) and (d) the pumps listed under Miscellaneous Equipment powered from the diesel generators (DGs) in the LAR.
Summary The NRC staff discussed Audit Items 3 through 8 in the audit plan. The NRC staff Audit Items 3, 4, 5, 6, 7, and 8 were resolved during the audit and no request for additional information (RAI) or supplement is needed.
ATTACHMENT 2 AUDIT DAY 2 - AUGUST 28, 2024 Attendees NAME ORGANIZATION John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Khoi Nguyen NRC Hadari Kodali NRC Michael Markley NRC Ken Lowery Southern Nuclear Operating Company (SNC)
Ryan Joyce SNC Justin Martin SNC Kyle Shelton SNC Dan Williamson SNC The audit commenced with the above attendees.
The following Audit Items were discussed.
Audit Item 1 - Methodology for establishing the proposed emergency diesel generator (EDG) voltage and frequency tolerances. If a calculation for these tolerances exists, a copy of such calculation should be available for auditing.
Audit Item 2 - EDG fuel consumption and EDG loading calculations against the EDG voltage and frequency variations.
Audit Item 3 - In Section 3.0 of the LAR, SNC concluded that Motor-Operated Valve (MOV) performance is not affected by the proposed EDG voltage and frequency ranges.
Provide the following:
- a. A sample calculation for MOV performance and for other motor driven loads such as fans, pumps, HVAC heaters,120 V AC etc., as applicable.
- b. A sample calculation for MOV or an evaluation, if exists, that evaluates the impact of the proposed change to the following:
MOV motor speed MOV inertia MOV voltage Pump output pressure and differential pressure on the MOV.
The following supplemental Audit Items were discussed.
Supplemental Audit Item 1 - Calculation X3CE11, Evaluation of the Effects of Emergency Diesel Generator Voltage and frequency Variations, Section 7.2, Fuel Oil Consumption, states The increase in the EDG loading is calculated in Appendix G. The effect of this increase on fuel oil consumption is addressed in a change to Reference 4.4. Reference 4.4 is Calculation X4C2403V08, Version 3.0. However, Page 1 of Calculation X4C2403V08 indicates Version 3.0 of this calculation addresses the impact of using ultra-low sulfur diesel fuel oil. It appears that the correct reference should be X4C2403V08, Version 4.0. Please clarify.
Supplemental Audit Item 2 - Calculation X3CE12, Operational Uncertainty for Vogtle Unit 1 and Unit 2 Emergency Diesel Generators, seems to be missing pages.
Section 8.1.2 documents the voltage uncertainty equation but not the actual calculation and result. Please clarify.
Supplemental Audit Item 3 - Calculation MC-V-20-0059, Figures 1.1 and 1.2, Frequency Block Diagram, show the different EDG engine speed governors between Unit 1 and Unit 2 (i.e., analog vs. digital). Describe any difference (if any) between Unit 1 and Unit 2 EDG frequency uncertainties and any impact to the proposed EDG frequencies.
Supplement Audit Item 4 - Discussion Vogtle Non-Conservative LAR Audit Discussion The LAR proposes the following changes:
SR 3.8.1.11 Revise from
- a. In 11.4 seconds after auto-start and during tests, achieves voltage 3750 V and 4330 V;
- b. In 11.4 seconds after auto-start and during tests, achieves frequency 58.8 Hz and 61.2 Hz; to
- a. In 11.4 seconds after auto-start and during tests, achieves voltage 3750 V and frequency 58.8 Hz;
- b. Achieves steady state voltage 4040 V and 4330 V and frequency 59.6 Hz and 60.4 Hz; NRC Staff Question In the above proposed change, please explain why the requirement in 11.4 seconds after auto-start and during tests is removed from Item (b) of the SR.
Supplement Audit Item 5 - Discussion Vogtle Non-Conservative LAR Audit Discussion SR 3.8.1.20 Revise from
... in 11.4 seconds, voltage 4025 V and 4330 V, and frequency 58.8 Hz and 61.2 Hz to
- a. In 11.4 seconds, voltage 4025 V and frequency 58.8 Hz, and
- b. Steady state voltage 4040 V and 4330 V, and frequency 59.6 Hz and 60.4 Hz NRC Staff Question In the above proposed change, which splits the SR to two separate steps, please explain why the requirement in 11.4 seconds after auto-start and during tests does not apply to Item (b) of the SR.
Discussion SNC is adopting Technical Specification Task Force (TSTF)-163, Revision 2, Minimum vs.
Steady State Voltage and Frequency (ML040500733), as well as changes to the steady state EDG operating voltage and frequency ranges consistent with WCAP-17308-NP-A, Treatment of Diesel Generator (DG) Technical Specification Frequency and Voltage Tolerances, (ML17215A232) methodology with this LAR.
Audit Items 1 and 2 and Supplement Audit Items 1, 2, 3, and 4 were resolved during the audit.
NRC staff requested a sample MOV calculation for valve 1HV-5118 be placed on portal for SNC review.
SNC placed the sample MOV calculation on the portal on September 16, 2024.
The NRC staff completed its review of the sample MOV calculation on September 19, 2024. The sample calculation considered 1HV-5118 as an example of the calculations performed in Appendix B of calculation X3CE11 to determine the impact of EDG frequency and voltage variations. The speed factor 2-percent was conservative compared to calculated 0.67-percent variation. The Total Torque Factor, using 2-percent speed factor, was calculated and then the Pullout Torque was calculated. The instrument uncertainty was considered and based on it, the calculation revised Total Torque Factor and Pullout torque were calculated. The MIDAS X3CE11 was revised and determined that the valve has no active function to close. In conclusion, the new closure limit was 434.7 ft-lbs.
This calculation involved calculation of torque values, such as Speed Factor, Pullout Torque, and Total Torque factor. In addition, this calculation also considered instrumentation uncertainty.
The voltage variation impact was negligible. With respect to electrical review, the NRC staff found the review of Appendixes A, B, D, F and G of X3CE11 adequate.
Summary The NRC staff discussed the above and were resolved during the audit and no RAI or supplement is needed.
ATTACHMENT 3 AUDIT DAY 3 - NOVEMBER 8, 2024 Attendees NAME ORGANIZATION John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Thomas Scarbrough NRC Ken Lowery Southern Nuclear Operating Company (SNC)
The audit commenced with the above attendees. During the audit, the NRC staff reviewed the documents in the electronic portal and prepared requests and questions for the licensee. This audit summary summarizes the requests and questions that were prepared by the staff and addressed by the licensee during the audit.
The NRC asked the following questions:
- 1. Appendix B, Review of GL 89-10 MOVs for the Effects of Variation in Motor Speed, in SNC Calculation X3CE11, Evaluation of the Effects of Emergency Diesel Generator Voltage and Frequency Variations, Version 3.0, September 28, 2023, found that motor-operated valve (MOV) 1HV5118 has a maximum closing torque higher than the current reduced structural limit. Calculation X3CE11 recommended that either HV5118 be reset to operate within the calculated limits, or the limits be re-evaluated to accept the current MOV setting. The licensee is requested to describe its actions to resolve the structural limit finding for MOV 1HV5118 in Calculation X3CE11.
- 2. Appendix C, Adjustment of Pump IST Acceptance Criteria and Comparison to Existing Test Results, to SNC Calculation X3CE11 indicates that the existing hydraulic analysis for the Boric Acid Transfer pumps does not adequately account for overpressure or maximum possible level of the volume control tank (VCT), which is directly connected to the charging pump suction. SNC Calculation X3CE11 recommended that the Boric Acid Transfer pump hydraulic analysis be revised to account for the overpressure and static head contribution of the VCT. The licensee is requested to describe its actions to resolve the calculation findings regarding the Boric Acid Transfer pump hydraulic analysis.
- 3. Appendix C to SNC Calculation X3CE11 indicates that VEGP Units 1 and 2 test procedure 14982-1 in Sections 6.1 and 6.2 has an acceptance criterion of 8.4 gallons per minute (gpm) for the flow provided by the diesel fuel oil transfer pumps. The calculation specifies that this is less than the required makeup at maximum consumption rate of 8.51 gpm. Appendix C states that Calculation X4C2403V02 provides a recommended test criterion of 18.2 gpm for the diesel fuel oil transfer pumps to meet the delivery requirements with sufficient margin for EDG uncertainty. The licensee is requested to describe its actions to resolve the discrepancy in test procedure 14982-1 regarding the supply flow rate for the diesel fuel oil transfer pumps.
- 4. Appendix C to SNC Calculation X3CE11 states that the auxiliary feedwater (AFW) pumps were addressed by a Prompt Determination of Operability (PDO). The licensee is requested to describe its evaluation of the EDG frequency and voltage variations on the performance of the AFW pumps.
- 5. In the 1HV-5118 Example White Paper, the licensee showed an example of the evaluations of MOVs performed in Appendix B of SNC Calculation X3CE11. The example calculation determined that both the Total Torque Factor and the Pullout Torque Factor are decreased when the instrument uncertainty and the EDG voltage and frequency variance are included in those factors. The licensee is requested to describe the basis for the reduction of the torque correction factors with the additional uncertainties.
- 6. Westinghouse Letter LTR-SEE-19-101, Revision 0, June 14, 2021, A.W. Vogtle Units 1
& 2 Pump Evaluations for Emergency Diesel Generator Frequency and Voltage, in Section 2.0, Summary of Results and Conclusions, describes several findings to be addressed for specific pumps based on the EDG frequency and voltage variations. The licensee is requested to describe the resolution of those findings for the specified pumps.
- 7. LAR to Revise Diesel Generator Frequency and Voltage Ranges for Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirements, dated March 20, 2024, states that the evaluation of the EDG voltage and frequency variations followed the methods in WCAP-17308-NP-A, Treatment of Diesel Generator (DG)
Technical Specification Frequency and Voltage Tolerances. The licensee is requested to describe any deviation from the methods specified in WCAP-17308-NP-A and the implementation in those methods, such as applied in SNC Calculation x3CE11, Westinghouse Letter LTR-SEE-19-101, and other calculations supporting the LAR.
Upon reviewing the licensee responses on the electronic portal to the above requests during the audit, the NRC staff asked SNC to provide the following referenced documents in the electronic portal:
Question 1: VNP-1HV5118 Question 2: TE114907 and X4C1208V01 Question 3: CR 11027149 Question 4: X4C1302V15 Question 6: TE1163836 and IST Impact Review form Following its review of the additional documents made available by the licensee in the electronic portal, the NRC staff asked follow-up questions as indicated below:
Question 1: Where is VNP-1HV5118 revised (electronic page number) as discussed?
Question 2: Where is X4C1208V01 revised (electronic page number) as discussed?
Question 3: Have Procedures 14982-1/2 been updated as indicated in CR 11027149? If so, can it be placed in CERTREC?
The NRC staff reviewed the licensee responses to these follow-up questions during the audit, and did not have any remaining questions.
Summary The NRC staff evaluated the licensees responses to the above requests and questions. The staff considered its requests and questions to have been resolved during the audit. As a result, the staff determined that no RAI or supplement is needed to complete its review of the EDG LAR for Vogtle, Units 1 and 2, with respect to pump and valve performance.
ATTACHMENT 4 AUDIT DAY 5 (AUDIT CLOSEOUT) - DECEMBER 9, 2024 Attendees NAME ORGANIZATION John G. Lamb U.S. Nuclear Regulatory Commission (NRC)
Ken Lowery Southern Nuclear Operating Company (SNC)
Closeout The audit commenced with the above attendees. After brief remarks, the NRC staff closed out the audit. The NRC staff made no regulatory decisions during the audit. The NRC staffs requests and questions were resolved during the audit. The NRC staff determined that no RAIs or supplements are needed to complete its review of the SNC LAR to Revise Diesel Generator Frequency and Voltage Ranges for Technical Specification 3.8.1, AC Sources - Operating, Surveillance Requirements, for Vogtle, Units 1 and 2.
In accordance with LIC-111, it states:
The regulatory audit summary report should be placed on the docket and in ADAMS within 90 days of the completion of the audit or before the regulatory action that the audit supports is completed, whichever is shorter.
The 90-day deadline for the audit summary report is March 10, 2025.
ML24337A122 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DSS/SNSB/BC NRR/DEX/EEEB/BC NAME JLamb KGoldstein DMurdock (A)
WMorton DATE 12/02/2024 12/03/2024 12/04/2024 12/04/2024 OFFICE NRR/DEX/EMIB/BC NRR/DORL/ LPL2-1/BC NRR/DORL/LPL2-1/PM NAME SBailey MMarkley JLamb DATE 12/04/2024 12/10/2024 12/10/2024