ML26007A227
| ML26007A227 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 01/14/2026 |
| From: | Tennessee Valley Authority |
| To: | Kimberly Green Office of Nuclear Reactor Regulation |
| Green K | |
| References | |
| EPID L-2025-LRM-0158 | |
| Download: ML26007A227 (0) | |
Text
TVA Alternative Request to Utilize Mechanical Agitation for the next Sequoyah Nuclear Plant (SQN) and Watts Bar Nuclear Plant (WBN) Inservice Testing (IST) Intervals January 14, 2026
Agenda Introduction
Background
Format and Methodology for the Alternative Requests for Mechanical Agitation for the next Sequoyah Nuclear Plant (SQN), Units 1 and 2 and the Watts Bar Nuclear Plant (WBN), Units 1 and 2, inservice testing (IST) intervals Path Forward l 2
Introduction Tennessee Valley Authority (TVA) is currently developing alternative requests for the next SQN Units 1 and 2 and the WBN Units 1 and 2, IST intervals. TVA is currently in the fourth IST interval for SQN Units 1 and 2, and the third IST interval for WBN Unit 1, and the first IST interval for WBN Unit 2.
The fourth IST interval for SQN Units 1 and 2, originally scheduled to end on June 30, 2026, was extended to December 15, 2026, as allowed by ISTA-3120(d). Therefore, the fifth IST interval for SQN Units 1 and 2 is required to begin no later than December 16, 2026. The WBN Unit 1 third IST interval, and the WBN Unit 2 first IST interval, are currently scheduled to end on October 18, 2026, for both units, but can be extended to May 27, 2027, as allowed by ISTA-3120(d). Therefore, the fourth IST interval for WBN Unit 1 and the second IST interval for WBN Unit 2 is required to begin no later than May 28, 2027. However, TVA is currently planning to commence the next WBN IST intervals as the same date as SQN.
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Introduction The Nuclear Regulatory Commission (NRC) previously approved an alternative request (RV-02) for the use of mechanical agitation for the SQN Units 1 and 2 pressure isolation valves (PIVs) for the remainder of the current SQN Units 1 and 2 IST interval.
TVA plans to request an alternative request for the forthcoming SQN Units 1 and 2 and the WBN Units 1 and 2 IST intervals to allow for mechanical agitation.
TVA plans to adopt the 2022 Edition of the ASME OM Code for these intervals.
Purpose of the meeting is to discuss the level of detail needed for these alternative requests.
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Background===
NRC initially approved the use of mechanical agitation for SQN Units 1 and 2 on September 29, 2022 (ML22263A375).
The above NRC safety evaluation also took credit for an NRC audit (ML22263A008) of the TVA technical evaluation (EWR No. 22-DEC-063-050) describing the methodology and process for performing mechanical agitation.
(Note: WBN has developed an identical technical evaluation
[EWR23CIV063075]).
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Background===
On March 6, 2025, TVA submitted a revision to SQN IST alternative request RV-02 (ML25085A280). The specific changes were:
Updated the frequency of SQN Units 1 and 2 Surveillance Requirement (SR) 3.4.14.1 regarding PIVs.
Revised the Description of the Proposed Alternative to include 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.
NRC approved the revision to SQN IST alternative request RV-02 on September 17, 2025 (ML25251A095)
TVA is also working with ASME OM Code Committee to develop a Code Case for the use of Mechanical Agitation l 6
Mechanical Agitation for the Forthcoming SQN and WBN IST intervals
- As previously noted, TVA plans to request the use of mechanical agitation for the SQN and WBN PIVs for their next IST intervals.
- The methodology, proposed alternative and basis for the alternative for performing mechanical agitation that was approved by NRC for SQN also applies to WBN
- Therefore, TVA plans to submit a single alternative request for both SQN and WBN for the use of mechanical agitation.
- TVA will provide any experience with mechanical agitation and leak rate history for the WBN PIVs similar to what was provided for SQN (ML22179A357) l 7
Mechanical Agitation for the Forthcoming SQN and WBN IST intervals
- In the alternative request, rather than repeating information that was previously reviewed and approved by the NRC, TVA proposes to reference the previous TVA and NRC correspondence, if acceptable to NRC.
- Since NRC approval of the Mechanical Agitation Alternative Request, there have not been any instances at SQN where the alternative request has been employed.
- Examples shown on following pages:
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Path Forward l 13
- The proposed SQN and WBN mechanical agitation alternative requests will be included in the TVA IST alternative requests for the upcoming SQN Units 1 and 2 fifth IST intervals, the WBN Unit 1 fourth IST interval, and the WBN Unit 2 second IST interval. TVA plans to adopt the 2022 Edition of the ASME OM Code for these intervals.
- TVA plans to have another presubmittal meeting with NRC to address all of the IST alternative requests for SQN and WBN for their upcoming IST intervals.
- TVA tentatively plans to request the next presubmittal meeting in March 2026.