05000259/LER-2021-001, Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications Due to Failed Relay

Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications Due to Failed Relay

ML21326A027
Person / Time
Site:	Browns Ferry
Issue date:	11/22/2021
From:	Rasmussen M Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 2021-001-00
Download: ML21326A027 (9)

LER-2021-001, Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications Due to Failed Relay

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function
2592021001R00 - NRC Website

text

Post Office Box 2000, Decatur, Alabama 35609-2000 November 22, 2021 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Units 1 and 2 Renewed Facility Operating License Nos. DPR-33 and DPR-52 NRC Docket Nos. 50-259 and 50-260

Subject:

Licensee Event Report 50-259/2021-001-00 The enclosed Licensee Event Report (LER) provides additional details of the 480 Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications (TS) due to Failed Relay. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations 50.73(a)(2)(i)(B), as any operation or condition which was prohibited by the plants TSs and 50.73(a)(2)(v), as any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to (A) shut down the reactor and maintain it in a safe shutdown condition; (B) remove residual heat, (C) control the release of radioactive material; and (D) mitigate the consequences of an accident.

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

Respectfully, Matthew Rasmussen Site Vice President Enclosure: Licensee Event Report 50-259/2021-001 480 Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications due to Failed Relay Matthew Rasmussen

U.S. Nuclear Regulatory Commission Page 2 November 22, 2021 cc (w/ Enclosure):

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

ENCLOSURE Browns Ferry Nuclear Plant Units 1and 2 Licensee Event Report 50-259/2021-001-00 480 Volt Load Shed Logic Inoperable Longer than Allowed by Technical Specifications due to Failed Relay See Enclosed

Abstract

On September 23, 2021 at 02:00 CDT (Central Daylight Time), the Units 1 and 2 480 Volt (V) Load Shed Logic, Division I was declared inoperable during the performance of surveillance testing. During the performance of this surveillance procedure, relay 0-RLY-231-00A7 would not have energized when required due to an open circuit in the coil. The relay was replaced and the Units 1 and 2 480 V Load Shed Logic, Division I was declared operable on September 25, 2021 at 22:30 CDT.

An engineering evaluation of the relay failure was completed on October 28, 2021. This evaluation determined that 0-RLY-231-00A7 was likely inoperable since the last time it had been energized during testing on March 3, 2021. Additionally, the Units 1 and 2 480 V Load Shed Logic, Division II was out of service twice during this time period to support testing on March 4, 2021 and May 19, 2021.

Examination of the relay determined that the relay failed due to an internal failure of the coil with no external damage seen.

The relay will be sent to the manufacturer for additional review for potential reportability under Title 10 of the Code of Federal Regulations Part 21.

Page 6 of 6 B. For events that occurred when the reactor was shut down, availability of systems or components needed to shutdown the reactor and maintain safe shutdown conditions, remove residual heat, control the release of radioactive material, or mitigate the consequences of an accident This event did not occur when the reactor was shut down.

C. For failure that rendered a train of a safety system inoperable, estimate of the elapsed time from discovery of the failure until the train was returned to service The relay was inoperable from March 3, 2021, until it was replaced on September 25, 2021 (approximately 206 days).

VI.

Corrective Actions

Corrective Actions for this event are being managed under Condition Report (CR) 1723229.

A. Immediate Corrective Actions

The failed relay was replaced and tested satisfactorily.

B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future The relay will be sent to the manufacturer for additional review for potential reportability under 10 CFR 21.

VII. Previous Similar Events at the Same Site

There were no previous similar events occurring at BFN within the last three years.

VIII. Additional Information

There is no additional information.

IX.

Commitments

There are no new commitments.