ML23325A110

Anchor Darling Double Disc Gate Valve Commitment Revision

ML23325A110
Person / Time
Site:	Browns Ferry
Issue date:	11/21/2023
From:	Sivaraman M Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
Download: ML23325A110 (1)

Text

1\14 TENNESSEE VALLEY AUTHORITY Post Office Box 2000, Decatur, Alabama 35609-2000 November 21, 2023 10 CFR 50.4 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1 and 3 Renewed Facility Operating License Nos. DPR-33 and DPR-68 NRC Docket Nos. 50-259 and 50-296

Subject:

Tennessee Valley Authority (TVA) - Browns Ferry Nuclear Plant Anchor Darling Double Disc Gate Valve Commitment Revision

Reference:

1. TVA letter to NRC, Tennessee Valley Authority (TVA) - Browns Ferry Nuclear Plant Anchor Darling Double Disc Gate Valve Commitment Revision, dated January 11, 2018 (ML18016A032).

2. TVA letter to NRC, Tennessee Valley Authority - Anchor Darling Double Disc Gate Valve Information and Status, dated December 28, 2017 (ML17362A566).

In the Reference letter dated December 28, 2017, TVA provided a listing of the Anchor Darling double disc gate valve (ADDDGV) population with active safety functions along with relevant valve information, including the results of susceptibility evaluations and repair status, for the Browns Ferry Nuclear Plant, Units 1, 2, and 3; and the Sequoyah Nuclear Plant, Units 1 and 2.

The Reference letter also confirmed that Watts Bar Nuclear Plant (WBN), Units 1 and 2, does not use ADDDGVs to support any active safety function.

The purpose of this letter is to provide updated commitments regarding the BFN Units 1 and 3 ADDDGV motor-operated valves that are categorized as Susceptible and Not Repaired.

On November 25, 2019, the Boiling Water Reactor Owners Group (BWROG) issued Topical Report TP16-1-112, Revision 5, Recommendations to Resolve Flowserve 10 CFR Part 21 Notification Affecting Anchor Darling Double Disc Gate Valve Wedge Pin Failures, which provided updated guidance for crediting thread friction between the stem and upper wedge, including the threshold friction values at which proactive repair is no longer recommended.

Specifically, Attachment 10 of TP16-1-112 provides the BWROG Valve Technical Resolution Group (VTRG) recommended actions for susceptible motor-operated valves (MOVs). The first option was to repair the valves and eliminate the condition. The second option was to reanalyze the wedge pin using a stem to upper wedge thread coefficient of friction (COF) of 0.2 or less to acquire positive wedge pin margin. If positive margin exists, then repair is not required. The MOV is then to be diagnostically tested at the following maximum intervals:

U.S. Nuclear Regulatory Commission Page 2 November 21, 2023 2 years, for tests 1 and 2.

4 years, for tests 3 and 4.

At the established GL 96-05 periodic verification / Appendix Ill in-service test interval for all future tests, if no active stem-wedge connection degradation is identified (i.e., an unsatisfactory stem rotation check and/or unresolved diagnostic test anomalies).

This testing will include stem rotation checks. BFN has reviewed the wedge pin margins and has determined that positive margin exists for the subject valves with the use of a stem to upper wedge thread COF of 0.2. Therefore, this condition has been met. Further support for cancelling the repair work on the subject valves was provided by the positive results of the inspections of the original stems following repair work performed on 2-FCV-068-0003, 2-FCV-068-0079 and 3-FCV-068-0079. The original stems from these valves were cut through the wedge pin centerline to determine if there was any indication of wedge pin shear, but no such indications were identified.

TVA, based on continued evaluation, has determined that the periodic monitoring of these valves is feasible, and is revising the BFN commitments to repair them. The Enclosure to this letter reflects the revised commitments for BFN Units 1 and 3 for the ADDDGV issue. These commitments supersede the unimplemented portions of Commitments 1 and 3 in the Enclosure to the first Reference letter. TVA may further modify these commitments should additional technical information or repair methods become available to justify such action.

Should you have any questions concerning this submittal, please contact David Renn, Site Licensing Manager, at (256) 729-2636.

Respectfully, Manu Sivaraman Site Vice President

Enclosure:

Summary of Commitments cc (Enclosure):

NRR Director - NRC Headquarters NRC Regional Administrator - Region II NRC Project Manager - Browns Ferry Nuclear Plant NRC Senior Resident Inspector - Browns Ferry Nuclear Plant

Enclosure Summary of Commitments

1. 1-FCV-068-0003 and 1-FCV-068-0079 will undergo Stem Rotation Checks and Diagnostic Testing in accordance with BWROG Topical Report TP16-1-112, Revision 5, Attachment 10, Option 2 beginning no later than Fall 2024 refueling outage.

1-FCV-075-0009 was repaired on October 22, 2022, under Work Order 119334041.

1-FCV-075-0037 was repaired on October 21, 2020, under Work Order 119334042.

2. 3-FCV-068-0003 will undergo Stem Rotation Checks and Diagnostic Testing in accordance with BWROG Topical Report TP16-1-112, Revision 5, Attachment 10, Option 2 beginning no later than the Spring 2024 refueling outage.

3-FCV-068-0079 was repaired on March 15, 2022, under Work Order 119334055.