LER-2024-001, Inoperability of Unit 3 Diesel Generator Due to Relay Failure |
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10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
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| 2592024001R01 - NRC Website |
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Post Office Box 2000, Decatur, Alabama 35609-2000 July 3, 2024 10 CFR 50.73 10 CFR 50.4(a)
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1, 2, and 3 Renewed Facility Operating License Nos. DPR-33, DPR-52, and DPR-68 NRC Docket Nos. 50-259, 50-260, and 50-296
Subject:
Licensee Event Report 50-259/2024-001-01
Reference:
Letter from TVA to NRC, Licensee Event Report 50-259/2024-001-00, dated April 11, 2024 (ML24102A279)
The enclosed Licensee Event Report provides details of an inoperability of a Unit 3 Diesel Generator. The Tennessee Valley Authority (TVA) is submitting this report in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.73(a)(2)(i)(B), as any operation or condition which was prohibited by the plants Technical Specifications.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact David Renn, Site Licensing Manager, at (256) 729-2636.
Respectfully, Daniel A. Komm BFN Site Vice President
Enclosure:
Licensee Event Report 50-259/2024-001 Inoperability of Unit 3 Diesel Generator due to Relay Failure cc (w/ Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant By Delegation for
Abstract
On February 14, 2024, while performing Surveillance Procedure 3-SR-3.8.1.9(3D OL), Diesel Generator 3D Emergency Load Acceptance Test with Unit 3 Operating, the Unit 3 D Emergency Diesel Generator (DG) did not start on an undervoltage condition on its associated safety bus as expected. BFN-3-RLY-082-D/SUDR (Single Unit Defeat Relay) contacts 3 and 4 are designed as normally closed but were found electrically open in the normal state causing the Diesel fast start circuit to not be made up.
The apparent cause of the misalignment of the SUDR relay contacts was the lack of effective Preventative Maintenance (PM). Improved PM Strategy to provide more detailed relay inspections /testing requirements for DG starting logic relays that have critical functions will be implemented.
During this event, the 3D DG would have continued to support the safety function of starting on the receipt of an accident signal as designed. Although the 3D DG would not have automatically started during a loss of offsite power, operators are directed to immediately ensure DGs are started and tied to their respective safety busses.
Page 7 of 7 IX.
Commitments
There are no new commitments.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
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