ML24039A079
| ML24039A079 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 02/12/2024 |
| From: | Perry Buckberg Plant Licensing Branch II |
| To: | Jim Barstow Tennessee Valley Authority |
| Wentzel M | |
| Shared Package | |
| ML24039A083 | List: |
| References | |
| EPID L-2020-LLA-0004 | |
| Download: ML24039A079 (21) | |
Text
CEII - DO NOT RELEASE CEII - DO NOT RELEASE February 12, 2024 Mr. James Barstow Vice President, Nuclear Regulatory Affairs and Support Services Tennessee Valley Authority 1101 Market Street Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 -
SUMMARY
OF REGULATORY AUDIT REGARDING THE LICENSE AMENDMENT REQUEST FOR HYDROLOGIC ANALYSIS CHANGES TO THE UPDATED FINAL SAFETY ANALYSIS REPORT (EPID L-2020-LLA-0004)
Dear Mr. Barstow:
By letter dated January 14, 2020 (Agencywide Documents Access and Management System Accession No. ML20016A396), as supplemented by letters dated February 18, 2020, May 14, 2020, August 12, 2020, November 10, 2020, June 15, 2021, August 13, 2021, December 21, 2021, and August 22, 2022 (ML20049H184, ML20135H067, ML20225A170, ML20328A093, ML21203A335, ML21239A115, ML22013A278, and ML22251A139, respectively), Tennessee Valley Authority (TVA) requested an amendment to the Renewed Facility Operating Licenses for Sequoyah Nuclear Plant, Units 1 and 2, to revise the Updated Final Safety Analysis Report (UFSAR) to reflect the results from a new hydrologic analysis. On April 11, 2023, TVA submitted a revised amendment request (ML23101A179), which was required to address issues with dam stability assumptions utilized in hydrologic analysis supporting the results and conclusions in the initial January 14, 2020, amendment request.
The U.S. Nuclear Regulatory Commission (NRC) staff conducted a virtual regulatory audit from September 14, 2020, through July 31, 2023, to support its review of the license amendment request. During the regulatory audit, the NRC staff reviewed documents and held discussions with members of TVA and its representatives. The regulatory audit summary is enclosed with this letter.
The NRC staff has determined that Attachment 3 to the Enclosure contains Critical Electric Infrastructure Information (CEII). Accordingly, the NRC staff has prepared a redacted version, which is provided in Attachment 4. CEII text is contained within double brackets (( this is CEII text )).
of the Enclosure to this letter contains Critical Electric Infrastructure Information (CEII). When separated from Attachment 3 to the Enclosure, this document is DECONTROLLED.
CEII - DO NOT RELEASE J. Barstow CEII - DO NOT RELEASE If you have any questions, please contact me at (301) 415-1383 or Perry.Buckberg@nrc.gov.
Sincerely,
/RA/
Perry H. Buckberg, Senior Project Manager Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328
Enclosure:
Regulatory Audit Summary cc: Listserv
CEII - DO NOT RELEASE Enclosure CEII - DO NOT RELEASE OFFICE OF NUCLEAR REACTOR REGULATION REGULATORY AUDIT
SUMMARY
IN SUPPORT OF LICENSE AMENDMENT REQUEST FOR THE REVISED HYDROLOGIC ANALYSIS TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
1.0 BACKGROUND
By letter dated January 14, 2020 (Agencywide Documents Access and Management System Accession No. ML20016A396), as supplemented by letters dated February 18, 2020, May 14, 2020, August 12, 2020, November 10, 2020, June 15, 2021, August 13, 2021, December 21, 2021, and August 22, 2022 (ML20049H184, ML20135H067, ML20225A170, ML20328A093, ML21203A335, ML21239A115, ML22013A278, and ML22251A139, respectively), Tennessee Valley Authority (TVA) requested an amendment to the Renewed Facility Operating Licenses for Sequoyah Nuclear Plant, Units 1 and 2, to revise the Updated Final Safety Analysis Report (UFSAR) to reflect the results from a new hydrologic analysis. On April 11, 2023, TVA submitted a revised license amendment request (LAR) (ML23101A179), which was required to address issues with dam stability assumptions utilized in hydrologic analysis supporting the results and conclusions in the initial January 14, 2020, amendment request.
Information that the Nuclear Regulatory Commission (NRC) staff relies upon to make the safety determination must be submitted on the docket. However, the NRC staff may review supporting information retained as records under Title 10 of the Code of Federal Regulations (10 CFR) 50.71, Maintenance of records, making of reports, and/or 10 CFR 54.37, Additional records and recordkeeping requirements, which, although not required to be submitted as part of the licensing action, would help the NRC staff better understand the licensees submitted information. To support its review of the LAR, the NRC staff issued a regulatory audit plan with an Information Request on September 14, 2020 (ML20261H418). The NRC Staff issued supplements to the audit plan with Information Requests on November 10, 2020, and March 9, 2021 (ML20316A018 and ML21068A408, respectively). The purpose of the audit is to review the documentation related to the subject of its application (e.g., calculations and reports) that were not submitted on the Sequoyah docket, to acquire additional understanding about the amendment request, and to determine whether additional information is needed to be docketed to complete the NRC staffs safety evaluation.
2.0 AUDIT ACTIVITIES The NRC audit team consisted of NRC staff and NRC contract support from the Oak Ridge National Laboratory (ORNL). Attachment 1 of this audit summary lists the individuals that took part in or attended the audit. The NRC audit team held a virtual entrance meeting with the licensee on September 17, 2020, and the virtual regulatory audit was conducted from September 17, 2020, through July 31, 2023. Throughout the audit period, the NRC audit team
CEII - DO NOT RELEASE CEII - DO NOT RELEASE would use an internet-based portal provided by the licensee to review primarily non-docketed information related to the application.
Technical discussions were focused on external hazards and software quality assurance, including activities supporting the commercial grade dedication of software used to perform the hydrologic engineering analysis. During the exit meeting, the NRC staff provided a brief conclusion of the entire audit including audit objectives that were met and details on the path forward. There were no open items from audit discussions and no deviations from the audit plan, as supplemented (see detail in Attachment 3). Non-docketed information provided by the licensee in response to audit questions and the formal meeting is listed in Attachment 2 of this audit summary.
3.0 RESULTS OF THE AUDIT As a result of the audit, TVA included information responsive to audit discussion points in its revised amendment request of April 11, 2023 (ML23101A179), which was determined sufficient to close the audit on July 31, 2023.
Attachments:
- 1. List of Participants
- 2. List of Documents Reviewed During Audit
- 3. Detail for Itemized Review During Audit
- 4. Detail for Itemized Review During Audit (Redacted)
CEII - DO NOT RELEASE CEII - DO NOT RELEASE List of Participants U.S. Nuclear Regulatory Commission (NRC) Audit Team Name Role, Branch Buckberg, Perry Project Manager, NRR/DORL/LPL2-2 Michael Wentzel Yuan Cheng Hosung Ahn Ken See Kevin Quinlan David Heeszel Deanna Zhang Scott DeNeale Shih-Chieh Kao Sudershan Gangrade Kevin Stewart Project Manager NRR/DORL/LPL2-2 Hydrologist NRR/DEX/EXHB Hydrologist NRR/DEX/EXHB Senior Hydrologist NRR/DEX/EXHB Meteorologist NRR/DEX/EXHB Seismologist NRR/DEX/EXHB Senior Reactor Operations Engineer NRR/DRO/IQVB Water Resource Engineer ORNL Hydrologist ORNL Hydrologist ORNL Water Resource Engineer ORNL NRC Acronyms:
NRR - Office of Nuclear Reactor Regulation; DORL - Division of Operating Reactor Licensing; LPL2 Plant Licensing Branch 2-2; DEX - Division of Engineering and External Hazards; EXHB - External Hazards Branch; DRO - Division of Reactor Oversight; IQVB - Quality Assurance and Vendor Inspection Branch; ORNL - Oak Ridge National Laboratory Tennessee Valley Authority Team Andrew Taylor Donald Lewis Dennis Lundy William Nesmith Gordon Williams Brenda Simril Thomas Spink Karen Carboni Laura Groce Husein Hasan Penny Selman Russ Wells Barge Design Solutions Stu Henry Heather Sawyer Janelle Schlamp Trevor Cropp Robert Blackwell
CEII - DO NOT RELEASE CEII - DO NOT RELEASE List of Documents Reviewed During Audit The licensee provided an extensive list of supporting documents (e.g., analyses, calculations, reports, drawings, and procedures) via the Sequoyah Nuclear Plant document portal available during the audit period. Below lists the documents available on the portal that the NRC audit team reviewed during the audit.
Probabilistic Risk Assessment Documents
- 1.
Local Intense Precipitation (LIP) Documentation
- a.
LAR Enclosure 4, Reference [54], Sequoyah Local Intense Precipitation Evaluation-SAR [Safety Analysis Report] Design Basis (Case 1) and Flood Hazard Re-evaluation Report (Case 2), Calculation CDQ0000002013000057, Revision 4.
- b.
Documentation describing the locations and modeling representations of vehicle barrier systems located within the plant site (if not already documented in Reference [54]).
- c.
Documentation describing the modeling representations of building roofs and associated discharge to the ground surface (if not already documented in Reference [54]).
- d.
Electronic version of LAR Enclosure 3, Figure 2.4.3-19 (as referenced in LAR, Section 2.4.2.3).
- 2.
Probable Maximum Flood (PMF) Documentation
- a.
LAR Enclosure 4, Reference [16], Areal Application of Probable Maximum Precipitation (PMP) Event Data for the Tennessee River Model above Wheeler Dam.
- b.
LAR Enclosure 4, Reference [23], Computer-Determined Unit Hydrographs From Floods.
- c.
LAR Enclosure 4, Reference [55], Chickamauga Dam (CHH) Probable Maximum Flood Analysis, Calculation CDQ0000002017000059, Revision 0.
- d.
Documentation of methodology, including dam failure parameters, used to simulate controlling scenario for PMF with hydrologic dam failures (e.g., References [30] through [35], [44] through [46], and [60] through
[61], as relevant).
- e.
PMF Summary Calculation, CDQ0000002017000070 R2
- f.
Project PMF Calculations
- g.
Project PMF Support Calculations
- h.
Project PMF Warning Time Calculation
- i.
TVA references (Calculations) used in the Audit Question Responses
- j.
Inner Nesting Analysis memorandum
- 3.
Seismic Dam Failure Documentation
- a.
LAR Enclosure 4, Reference [57], Seismic Dam Failure Combined with Rainfall Event Simulations, Calculation CDQ0000002014000024, Revision 5.
- b.
Site response inputs and results as well as 10,000-year response spectra (tables, if available) for four specific dams
CEII - DO NOT RELEASE CEII - DO NOT RELEASE
- c.
Documentation of TVA stability analyses specific critical dams above a specific dam that were assumed to fail under the controlling PMP storm event, including headwater elevation associated with assumed dam failure conditions (as referenced in LAR Enclosure 4, Section 2.4.4.1).
- d.
Documentation of methodology, including dam failure parameters, used to simulate controlling scenario for seismic dam failures.
- 4.
Wind Wave Activity Documentation
- a.
LAR Enclosure 4, Reference [56], Wind Waves for Combined Effect Floods, Calculation CDQ0000002017000059, Revision 0.
- 5.
Software Quality Assurance and Documentation
- a.
Dedication of the PMP Evaluation Tool
- i.
Documentation on the methodology, test cases, and test results to independently validate the output of the PMP Evaluation Tool.
ii.
Documentation that provides basis to demonstrate that the test cases selected to validate the output of the PMP Evaluation Tool is sufficient to dedicate this tool for use in the intended application as described in the LAR.
iii.
Information to respond to NRC staff questions related to the dedication and operation of the PMP Evaluation tool as described in the November 10, 2020, Audit Plan Supplement (ML20316A018).