ML25251A095
| ML25251A095 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/17/2025 |
| From: | David Wrona Plant Licensing Branch II |
| To: | Erb D Tennessee Valley Authority |
| References | |
| EPID L-2025?LLR-0039 | |
| Download: ML25251A095 (1) | |
Text
September 17, 2025 Mr. Delson C. Erb Vice President, OPS Support Tennessee Valley Authority 1101 Market Street, LP 4A-C Chattanooga, TN 37402-2801
SUBJECT:
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 AUTHORIZATION OF REVISED ALTERNATIVE REQUEST RV-02 FOR PRESSURE ISOLATION VALVE SEAT LEAKAGE (EPID L-2025-LLR-0039)
Dear Mr. Erb:
By letter dated March 26, 2025, Tennessee Valley Authority (TVA) submitted Revised Alternative Request RV-02 to the U.S. Nuclear Regulatory Commission (NRC) related to certain Inservice Testing (IST) requirements in the American Society of Mechanical Engineers (ASME)
Code for Operation and Maintenance of Nuclear Power Plants (OM Code), Section IST, Rules for Inservice Testing of Light-Water Reactor Power Plants, for 26 pressure isolation valves at Sequoyah Nuclear Plant (SQN), Units 1 and 2.
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR), Section 50.55a, Codes and Standards, paragraph (z)(2), TVA submitted the revised alternative on the basis that compliance with the ASME OM Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality or safety.
The NRC staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that TVA has adequately addressed the regulatory requirements set forth in 10 CFR 50.55a(z)(2). Therefore, the NRC staff authorizes the use of Revised Alternative Request RV-02 at SQN, Units 1 and 2, for the remainder of the Fourth 10-year IST Program interval, which is scheduled to end on June 30, 2026.
Please direct any inquiries to Ms. Kimberly Green at 301-415-1627 or Kimberly.Green@nrc.gov.
Sincerely, David Wrona, Chief Plant Licensing Branch II-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-327 and 50-328
Enclosure:
Safety Evaluation cc: Listserv DAVID WRONA Digitally signed by DAVID WRONA Date: 2025.09.17 14:38:32 -04'00'
Enclosure SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REVISED ALTERNATIVE REQUEST RV-02 FOURTH 10-YEAR INSERVICE TESTING PROGRAM INTERVAL TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NUMBERS 50-327 AND 50-328 EPID NO. L-2025-LLR-0039
1.0 INTRODUCTION
By letter dated March 26, 2025 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML25085A280), the Tennessee Valley Authority (TVA or licensee) submitted Revised Alternative Request RV-02 to the U.S. Nuclear Regulatory Commission (NRC). Specifically, TVA requested a revision to a previously authorized alternative to certain Inservice Testing (IST) requirements in the American Society of Mechanical Engineers (ASME)
Code for Operation and Maintenance of Nuclear Power Plants (OM Code), Section IST, Rules for Inservice Testing of Light-Water Reactor Power Plants, at Sequoyah Nuclear Plant (SQN),
Units 1 and 2. The alternative allows mechanical agitation to assist in seating 26 specific check valves that function as pressure isolation valves (PIVs). This alternative was requested pursuant to Title 10 of the Code of Federal Regulations, Section 50.55a, Codes and standards, paragraph (z)(2), on the basis that compliance with the ASME OM Code requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality or safety.
As background, by letter dated March 15, 2022 (ML22074A315), as supplemented by letters dated June 28, 2022 (ML22179A357), and October 31, 2022 (ML22304A146), TVA requested NRC authorization of Alternative Request RV-02. By letter dated December 1, 2022 (ML22304A186), the NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2, for 26 PIVs, which allows mechanical agitation of those PIVs as part of IST testing. After Alternative Request RV-02 was authorized, TVA submitted a license amendment request (LAR)
(ML24331A178) to revise SQN, Units 1 and 2, Technical Specification (TS) 3.4.14, [Reactor Coolant System] RCS Pressure Isolation Valve (PIV) Leakage, Surveillance Requirement (SR) 3.4.14.1, to only reference the IST Program for the FREQUENCY. In response to a request for additional information (ML25041A301), TVA stated that it would submit a revision to Alternative Request RV-02 within 30 days following NRC approval of the LAR that would address approved changes to SR 3.4.14.1 performance frequency requirements and changes in the basis for the proposed alternative. The NRC staff approved the amendments to SQN, Units 1 and 2, by letter dated March 6, 2025 (ML25027A314).
The NRC staffs evaluation of Revised Alternative Request RV-02 remains the same as the staff previously authorized on December 1, 2022 (ML22304A186), with changes as noted below.
2.0 REGULATORY EVALUATION
See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
3.0 TECHNICAL EVALUATION
3.1 Licensees Revised Alternative Request RV-02 3.1.1 Applicable ASME OM Code Edition and Addenda See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
3.1.2 ASME Code Components Affected See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
3.1.3 Applicable ASME OM Code Requirements See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
3.1.4 Licensees Reason for Request See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2, (ML22304A186).
In Revised Alternative Request RV-02, TVA provided the following updated Reason for Request, based on the NRC-approved LAR for SQN, Units 1 and 2, by letter dated March 6, 2025 (ML25027A314):
The frequency of SR 3.4.14.1 is: In accordance with the Inservice Testing Program.
3.1.5 Licensees Proposed Alternative See previous NRC staff authorized Alternative Request RV-02 for SQN Units 1 and 2 (ML22304A186).
In Revised Alternative Request RV-02, TVA provided the following updated Description of the Proposed Alternative, based on the NRC-approved LAR for SQN, Units 1 and 2 (ML25027A314):
For PIVs that have been mechanically agitated and subsequently opened by flow during shutdowns, the required seat leakage tests will be performed, and acceptable results obtained prior to entering Mode 2 or the plant cannot start up.
If needed, the mechanical agitation can be re-performed.
3.1.6 Licensees Basis for Proposed Revised Alternative See previous NRC staff authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
In Revised Alternative Request RV-02, TVA provided the following updated Basis for Proposed Alternative, based on the NRC-approved LAR for SQN, Units 1 and 2 (ML25027A314):
Once PIVs are closed with acceptable seat leakage rate, the PIVs would not be required to open unless a loss of coolant accident (LOCA) occurred (or normal shutdown cooling flow for the RHR [residual heat removal] PIVs) and would not be required to perform the PIV function again following a LOCA. Should a LOCA occur, the plant would be shutdown for an extended period of time, which would allow the maintenance planned for the next refueling outage to be performed prior to startup following the LOCA. For PIVs that have been mechanically agitated and subsequently opened by flow during shutdowns, the required seat leakage tests will be performed, and acceptable results obtained prior to entering Mode 2 or the plant cannot start up. There has not been any instance at SQN where a PIV failed to open when required.
In addition, TVA provided additional justification for its proposed revised alternative that the NRC staff summarizes below:
TVA provided a detailed description of its review of the maintenance history of the PIVs within the scope of its alternative request. TVA stated that Condition Reports and Work Orders for each PIV were reviewed back to the Cycle 17 Refueling Outage (R17) for both units (spring 2010 for SQN, Unit 1, and spring 2011 for SQN, Unit 2). In its submittal, TVA identified intrusive maintenance activities that were performed for specific check valve sizes and types.
3.2
NRC Staff Evaluation
The information in Revised Alternative Request RV-02 for SQN, Units 1 and 2, submitted on March 26, 2025, does not affect the NRC Staff Evaluation section prepared for the previously authorized Alternative Request RV-02 for SQN, Units 1 and 2 (ML22304A186).
4.0 CONCLUSION
As described above and in the safety evaluation for SQN, Units 1 and 2, Alternative Request RV-02 dated December 1, 2022 (ML22304A186), the NRC staff has determined that TVA has justified its proposed mechanical agitation process described in the Revised Alternative Request RV-02, dated March 26, 2025, to be applied, if a PIV within the scope of this request fails its ASME OM Code-required leakage test, as an alternative to the applicable requirements in the ASME OM Code (2004 Edition through 2006 Addenda), as incorporated by reference in 10 CFR 50.55a. The NRC staff has also determined that the proposed alternative as specified in Revised Alternative Request RV-02, with its reference to the NRC-authorized Alternative Request RV-02 and the specified changes, will provide reasonable assurance of the operational readiness of the applicable PIVs until the next refueling outage when repair or replacement activities will be conducted, in light of the hardship caused by implementation of the applicable ASME OM Code requirements without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that TVA has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2) for Revised Alternative Request RV-
- 02. Therefore, the NRC staff authorizes the use of Revised Alternative Request RV-02 at SQN, Units 1 and 2, for the remainder of the Fourth 10-year IST Program interval, which is scheduled to end on June 30, 2026.
All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief or an alternative was not specifically requested and authorized remain applicable.
Principal Contributors: G. Bedi, NRR T. Scarbrough, NRR Dated: September 17, 2025
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