05000296/LER-2024-002, Breaker Trip Automatically Started an Emergency Diesel Generator

Breaker Trip Automatically Started an Emergency Diesel Generator

ML24115A165
Person / Time
Site:	Browns Ferry
Issue date:	04/24/2024
From:	Sivaraman M Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
LER 2024-002-00
Download: ML24115A165 (1)

LER-2024-002, Breaker Trip Automatically Started an Emergency Diesel Generator

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
2962024002R00 - NRC Website

text

Post Office Box 2000, Decatur, Alabama 35609-2000 April 24, 2024 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 3 Renewed Facility Operating License No. DPR-68 NRC Docket No. 50-296

Subject:

Licensee Event Report 50-296/2024-002-00 The enclosed Licensee Event Report provides details of a breaker trip which automatically started an Emergency Diesel Generator on Browns Ferry Nuclear Plant, Unit 3. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.73(a)(2)(iv)(A), as an event or condition that resulted in the unplanned, valid, manual or automatic actuation of emergency AC electrical power systems.

There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact David J. Renn, Nuclear Site Licensing Manager, at (256) 729-2636.

Respectfully, Manu Sivaraman Site Vice President Enclosure: Licensee Event Report 50-296/2024-002 Breaker Trip Automatically Started an Emergency Diesel Generator cc (w/ Enclosure):

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant TENNESSEE VALLEY AUTHORITY

ENCLOSURE Browns Ferry Nuclear Plant Unit 3 Licensee Event Report 50-296/2024-002-00 Breaker Trip Automatically Started an Emergency Diesel Generator See Enclosed

Abstract

On February 24, 2024, at approximately 0219 Central Standard Time (CST), the closing 4kV shutdown board (SDBD) breaker (3-BKR-211-03EB/009) caused the 3EB 4kV SBDB normal feeder breaker (3-BKR-211-03EB/014) to unexpectedly trip open. This trip resulted in a valid 4kV bus under-voltage condition, which caused the 3B emergency diesel generator (EDG) to automatically start and tie to the board.

No components failed during this event, which was ultimately attributed to an intermittent loose connection. Corrective measures included additional monitoring during cycling of board loads, trouble shooting and tightening of all accessible connections. The condition was unable to be repeated.

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Commitments

There are no new commitments.