05000259/LER-2016-001, Regarding Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves

Regarding Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves

ML16173A251
Person / Time
Site:	Browns Ferry
Issue date:	06/21/2016
From:	Bono S Tennessee Valley Authority
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 16-001-00
Download: ML16173A251 (8)

LER-2016-001, Regarding Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
LER closed by
IR 05000259/2016000 (9 November 2016) IR 05000259/2016003 (9 November 2016)
2592016001R00 - NRC Website

text

Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 June 21, 2016 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001

Subject:

Browns Ferry Nuclear Plant, Unit 1 Renewed Facility Operating License No. DPR-33 NRC Docket No. 50-296 Licensee Event Report 50-259/2016-001-00 10 CFR 50.73 The enclosed Licensee Event Report provides details of the failure of the 4kV Shutdown Bus Normal Feeder Breaker, the resulting actuation of C and D Emergency Diesel Generators, and the resulting actuation of multiple Containment Isolation Valves. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations 50.73(a)(2)(iv)(A), as any event or condition that results in manual or automatic actuation of any of the systems listed in paragraph (b)(3)(iv)(B) Emergency AC Electrical Power Systems including Emergency Diesel Generators, and Containment Isolation Valves.

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

Enclosure: Licensee Event Report 50-259/2016-001 Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves cc (w/ Enclosure):

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

ENCLOSURE Browns Ferry Nuclear Plant Unit 1 Licensee Event Report 50-259/2016-001-00 Failure of 4kV Shutdown Board Normal Feeder Breaker Results in Actuations of Emergency Diesel Generators and Containment Isolation Valves See Enclosed A. Availability of systems or components that could have performed the same function as the components and systems that failed during the event:

During this event, all four Unit 1 and 2 EDGs remained available, and all four Unit 1 and 2 4kV SD BDs were operable.

B. For events that occurred when the reactor was shut down, availability of safety-related systems or components:

This event did not occur when the reactor was shut down.

C. For failure that rendered a train of a safety system inoperable, an estimate of the elapsed time from discovery of the failure until the train was returned to service:

No safety systems were rendered inoperable as a result of this event.

VI.

Corrective Actions

Corrective Actions (CA) are being managed by TVAs Corrective Action Program (CAP) under Condition Report (CR) 1163613. The CAs described below address this condition:

1. Terminate loose wires, using a ring type lug instead of a forked spade type lug, in the closing control circuit for BFN-0-BKR-211-000C/026.

2. Verify Shutdown Bus 2 transfers to normal feed breaker in accordance with 0-OI-57A.

A briefing was provided to Electrical personnel that perform modifications to discuss the potential consequences of performing activities that could adversely affect existing wiring.

A. Previous Similar Events

A review of the BFN CAP and Licensee Event Reports for Units 1, 2, and 3 revealed no events over the last three years where a loose wire resulted in actuation of an EDG.

B. Additional Information

There is no additional information.

C. Safety System Functional Failure Consideration:

No safety systems were rendered inoperable as a result of this event. Therefore, this event is not considered to be a Safety System Functional Failure in accordance with NUREG-1022.

D. Scram with Complications Consideration:

This event did not result in a reactor scram.

VIII. COMMITMENTS

There are no new commitments.