ML23059A456
| ML23059A456 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 03/10/2023 |
| From: | John Lamb NRC/NRR/DORL/LPL2-1 |
| To: | Gayheart C Southern Nuclear Operating Co |
| References | |
| EPID L-2022-LLA-0097 | |
| Download: ML23059A456 (1) | |
Text
March 10, 2023 Mr. R. Keith Brown 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
FOR LICENSE AMENDMENT REQUEST TO ALLOW USE OF ACCIDENT-TOLERANT FUEL LEAD TEST ASSEMBLIES (EPID L-2022-LLA-0097)
Dear Mr. Brown:
By letter dated June 30, 2022 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML22181B156), as supplemented by letters dated September 13, 2022 (ML22256A198) and January 20, 2023 (ML23020A148), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2, to allow the use of lead test assemblies (LTAs) for accident-tolerant fuel (ATF).
The U.S. Nuclear Regulatory Commission (NRC) staff identified the need for a regulatory audit to examine the SNCs non-docketed information with the intent to gain understanding, to verify information, or to identify information that will require docketing to support the basis of the licensing or regulatory decision.
To support its review, the NRC staff conducted a virtual regulatory audit on December 6-8, and 15, 2022, and February 28, 2023. The NRC staff reviewed documents and held discussions with members of SNC and its contractors. The regulatory audit summary is enclosed with this letter.
R. Keith Brown If you have any questions, please contact me by telephone at (301) 415-3100 or by email at John.Lamb@nrc.gov.
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 Summary
Enclosure OFFICE OF NUCLEAR REACTOR REGULATION REGULATORY AUDIT
SUMMARY
FOR DECEMBER 6-8, AND DECEMBER 15, 2022 AND FEBRUARY 28, 2023 IN SUPPORT OF LICENSE AMENDMENT AND EXEMPTION REQUESTS TO ALLOW USE OF ACCIDENT-TOLERANT FUEL LEAD TEST ASSEMBLIES SOUTHERN NUCLEAR OPERATING COMPANY VOGTLE ELECTRIC GENERATING PLANT, UNITS 1 AND 2 DOCKET NOS. 50-424 AND 50-425
1.0 BACKGROUND
By letter dated June 30, 2022 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML22181B156), as supplemented by letters dated September 13, 2022 (ML22256A198), and January 20, 2023 (ML23020A148), Southern Nuclear Operating Company (SNC, the licensee) submitted a license amendment request (LAR) and exemptions for Vogtle Electric Generating Plant (Vogtle), Units 1 and 2, to allow the use of lead test assemblies (LTAs) for accident-tolerant fuel (ATF).
The U.S. Nuclear Regulatory Commission (NRC) staff identified the need for a regulatory audit to examine the SNCs non-docketed information with the intent to gain understanding, to verify information, or to identify information that will require docketing to support the basis of the licensing or regulatory decision.
On October 7, 2022 (ML22103A253), NRC issued an audit plan, which provided the list of requested documents and other details pertaining to the audit. An audit team, consisting of NRC staff conducted a remote regulatory audit to support the review of the LAR from December 6-8, and December 15, 2022, and February 28, 2023. The purpose of the audit was to gain an understanding of the information needed to support the NRC staffs licensing decision regarding the LAR and to develop requests for additional information (RAIs), if necessary. The information submitted in support of the LAR is under final review, and any additional information needed to support the LAR review will be formally requested by the NRC staff using the RAI process in accordance with Office of Nuclear Reactor Regulation (NRR) Office Instruction LIC-101, Revision 6, License Amendment Review Procedures (ML19248C539).
By letter dated November 8, 2022 (ML22279B053), as supplemented by emails dated as supplemented by emails dated November 17 and December 2, 2022, and January 22, 2023 (ML22322A019, ML22339A009, and ML23026A012, respectively), the NRC staff issued the agenda for the Audit.
2.0 AUDIT ACTIVITIES The NRC audit team consisted of several staff from NRC Office of Nuclear Reactor Regulation (NRR). Attachment 1 of this enclosure provides the list of participants from NRC, the licensee, and the licensees contractor.
The NRC audit team held an entrance meeting with the licensees staff and contractors on December 6, 2022. During the remainder of the audit, the NRC audit team participated in technical discussions with the licensee based on discipline according to the audit agenda and topics dated November 8, 2022 (ML22279B053), as supplemented by email dated November 17 and December 2, 2022 (ML22322A019 and ML22339A009, respectively). The audit was extended from January 31, 2023, to February 28, 2023 (ML23026A012). of the enclosure includes a list of documents reviewed during the audit.
3.0 RESULTS OF THE AUDIT Technical discussions were focused on the following major areas: (1) Cladding Emissivity, (2) ADOPT' pellets and AXIOM' cladding, (3) effects of LTAs on co-resident fuel, (4) peaking factors, (5) spent fuel criticality, control rod ejection accident, (6) radiation dose, and (7) technical specifications (TSs). The NRC audit team participated in an audit meeting with the licensee on December 6-8, 2022, where the NRC staff provided a brief summary of the teams goals, and objectives. There were 15 audit questions and/or topics; all 15 audit questions and/or topics were discussed.
On December 6, 2022, the NRC staff discussed the following: (1) cladding emissivity, (2) ADOPT pellets and AXIOM cladding, (3) effects of LTAs on co-resident fuel, (4) peaking factors, and (5) control rod ejection accident. The NRC staff provided audit question #1 to SNC regarding cladding emissivity by email dated December 6, 2022 (ML22340A649 - public).
On December 7, 2022, the NRC staff discussed the following questions and/or topics:
How does doping the fuel assemblies affect enrichment?
Why arent Integral Fuel Burnable Absorbers (IFBA) used in ADOPT fuel rods?
Are the LTAs over or under moderated?
How do the LTAs impact the spent fuel pool (SFP) isothermal temperature coefficient/moderator temperature coefficient (ITC/MTC), if separated and if co-located?
Walk through the differences between the new fuel storage rack (NFSR) analysis of record (AOR) in ELV-00511 (ML20244D557) Application for amends to Licenses NPF-68 and NPF-81, revising Tech Specification 5.3.1 to change maximum enrichment to 4.55 weight percent U-235, and the analysis done for the NFSR for the LTA storage in CN-WFE-02-100.
Walk through the differences between the SFP AOR in CN-WFE-02-100 and the analysis done for the SFP All-Cell LTA storage in CN-CRIT-VOG-003.
New Fuel Vault Discussion related to the supporting analysis to reach the submittal conclusions for the Rod Ejection Accident.
On December 8, 2022, the NRC staff discussed topics related to radiation and dose.
On December 15, 2022, the NRC staff discussed the status of the audit questions or topics.
SNC stated that it would provide a supplement by January 20, 2023, to address the emissivity and radiation dose topics. SNC submitted a supplement dated January 20, 2023 (ML23020A148).
contains the disposition of the audit questions or topics.
On February 28, 2023, a meeting was held to exit the Audit.
Attachments:
- 1. List of Participants
- 2. List of Documents Reviewed During Audit
- 3. Status of Audit Questions
LIST OF PARTICIPANTS NAME AFFLIATION John G. Lamb NRC/NRR/DORL David Garmon-Candelaria NRC/NRR/DRA/ARCB Kent Wood NRC/NRR/DSS/SFNB Brandon Wise NRC/NRR/DSS/SFNB Charley Peabody NRC/NRR/DSS/SNSB Joshua Wilson NRC/NRR/DSS/STSB Zena Abdullah NRC/ACRS staff engineer Mike Markley NRC Scott Krepel NRC Matt Panicker NRC Diana Woodyatt NRC Kent Howard NRC Ernest Bates Southern Nuclear Operating Company (SNC)
Ryan Joyce SNC Amy Chamberlain SNC Jennifer Baker SNC Matthew Leonard SNC Tom Kindred SNC Jason Douglass SNC James Smith Westinghouse Michael Wenner Westinghouse Radu Pomirleanu Westinghouse Ann Marie DiLullo Westinghouse Michael Anness Westinghouse Robert Schillat Westinghouse Dustin Staub Westinghouse Allen Jaworski Westinghouse Uriel Bachrach Westinghouse Ryan Rossman Westinghouse Dave Rumschlag Westinghouse Gregory Stehle Westinghouse Brian Pasco Westinghouse Guirong Pan Westinghouse John Moorehead Westinghouse Dave Mitchell Westinghouse Carrie Wood Westinghouse Tim Crede Westinghouse Jerry Akers Westinghouse Michael Boone Westinghouse Serhat Lider Westinghouse Bedirhan Akdeniz Westinghouse Yixing Sung Westinghouse Jessie Klingensmith Westinghouse NRC - U.S. Nuclear Regulatory Commission NRR - Office of Nuclear Reactor Regulation DORL - Division of Operating Reactor Licensing DRA - Division of Risk Assessment DSS - Division of Safety Systems ARCB - Radiation Protection and Consequence Branch STSB - Technical Specifications Branch SNSB - Nuclear Systems Performance Branch SFNB - Nuclear Methods and Fuel Branch ACRS - Advisory Committee on Reactor Safeguards
LIST OF DOCUMENTS REVIEWED DURING THE AUDIT Vogtle, Units 1 and 2, Documents Available for Review on the Portal Southern Nuclear Operating Company (SNC, the licensee) and its contractor, Westinghouse, provided documents on the Westinghouse document portal for review in support of the audit, as follows:
Item #
Audit Item 1
The Westinghouse evaluation discussed in the Non-LOCA (loss-of-coolant accident) Transients in Section 3.4. The third paragraph of that section references a Westinghouse evaluation to address the potential effects of the LTAs on non-LOCA transient events, and then lists five conclusions of that evaluation.
2 The evaluation performed to determine the impact from LTAs on the unfavorable exposure time in the anticipated transient without scram (ATWS) probabilistic risk assessment (PRA) model.
3 The evaluation, described in paragraph 1 of Section 3.1, to determine the impact of 16 higher enrichment lead test rods (four LTAs, each with four higher enrichment fuel rods) on the core radionuclide inventory used for radiological/dose consequences.
4 The evaluation, described in paragraph 4 of Section 3.1, comparing the core inventory for a core design implementing LTAs and the core inventory used for radiological/dose consequences.
5 The evaluations supporting the following conclusions in Section 3.4 It has been confirmed that inclusion of the LTAs does not increase the amount of fuel damage considered in the radiological consequences analyses of the locked rotor or rod ejection accident in the analyses of record, i.e., 5% for locked rotor with no fuel melting and 10% for rod ejection with melting limited to less than the innermost 10% of the fuel pellet at the hot spot (LR, CRE).
It has been confirmed that the LTAs do not impact the core average nuclide activities used to determine the activity released from fuel assumed to fail following a locked rotor, rod ejection accident, or LOCA (LR, CRE, LOCA).
The activities of dose significant radionuclides postulated for release in a fuel handling accident (FHA) involving the LTAs (e.g., Xe-133, Xe-135, I-131, I-132, I-133) are bounded by the activities of the same radionuclides in the existing FHA analyses.
6 The Analysis of Record Criticality Safety Analysis documents, and any Criticality Safety Analysis or evaluations performed to support the LAR.
7 Analyses and any supplemental information related to the emissivity of coated cladding during a LOCA. Specifically, analyses related to how the emissivity changes with time during a LOCA or the net effect of a reduction in emissivity on PCT.
8 Analyses and documentation, if any, demonstrating compliance with L&C 1 of WCAP-18482-P, requiring licensees to demonstrate that control rod ejection analytical models, methods, and acceptance criteria are applicable to fuel designs containing ADOPT pellets and capture all relevant fuel burnup and cladding corrosion related phenomena.
AUDIT QUESTIONS OR TOPICS Audit Question or Topic #
Question or Topic Status 1
With respect to cladding emissivity, the NRC staff is interested in information related to the rate at which emissivity increases during loss-of-coolant accident (LOCA) conditions in order to determine if the (( )).
Alternatively, the NRC staff is interested in a LOCA analysis measuring the total increase in peak clad temperature (PCT) with a conservatively low emissivity compared to a typical emissivity (ML22340A649).
Supplement dated January 20, 2023 ML23020A148 2
ADOPT pellets and AXIOM cladding Resolved 3
Effects of LTAs on co-resident fuel Resolved 4
Peaking Factors Resolved 5
Burn up Resolved 6
How does doping the fuel assemblies affect enrichment?
Resolved 7
Why arent IFBA used in ADOPT fuel rods?
Resolved 8
Are the LTAs over or under moderated?
Resolved 9
How do the LTAs impact the SFP ITC/MTC, if separated and if co-located?
Resolved 10 Walk through the differences between the NFSR AOR in ELV-00511 (ML20244D557) Application for amends to Licenses NPF-68 and NPF-81, revising Tech Spec 5.3.1 to change max enrichment to 4.55 weight percent U-235. And the analysis done for the NFSR for the LTA storage in CN-WFE-02-100.
Resolved 11 Walk through the differences between the SFP AOR in CN-WFE-02-100 and the analysis done for the SFP All-Cell LTA storage in CN-CRIT-VOG-003.
Resolved 12 New Fuel Vault Resolved 13 Discussion related to the supporting analysis to reach the submittal conclusions for the Control Rod Ejection Accident Resolved 14 Discussion of topics related to radiation and dose Supplement dated January 20, 2023 ML23020A148 15 RFOL and TSs Resolved
ML23059A456 OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DSS/STSB/BC NRR/DSS/SFNB/BC NAME JLamb KGoldstein VCusumano SKrepel DATE 02/28/2023 03/01/2023 03/02/2023 03/07/2023 OFFICE NRR/DSS/SNSB/BC NRR/DORL/LPL2-1/BC NRR/DORL/LPL2-1/PM NAME DWoodyatt MMarkley JLamb DATE 03/08/2023 03/09/2023 03/10/2023