05000327/LER-2024-001, Reactor Trip Due to a Turbine Trip

Reactor Trip Due to a Turbine Trip

ML24295A020
Person / Time
Site:	Sequoyah
Issue date:	10/17/2024
From:	Marshall T Tennessee Valley Authority
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
LER 2024-001-00
Download: ML24295A020 (1)

LER-2024-001, Reactor Trip Due to a Turbine Trip

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
3272024001R00 - NRC Website

text

Sequoyah Nuclear Plant, Post Office Box 2000, Soddy Daisy, Tennessee 37384 October 17, 2024 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Sequoyah Nuclear Plant, Unit 1 Renewed Facility Operating License No. DPR-77 NRC Docket No. 50-327

Subject:

Licensee Event Report 50-327/2024-001-00, Reactor Trip due to a Turbine Trip The enclosed licensee event report provides details concerning an automatic reactor trip on an electrical trouble turbine trip. This report is being submitted in accordance with 10 CFR 50.73(a)(2)(iv), as an event that resulted in an automatic actuation of the reactor protection system and the auxiliary feedwater system. A supplement to this LER will be submitted following completion of the associated root cause evaluation.

There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. Rick Medina, Site Licensing Manager, at (423) 843-8129 or rmedina4@tva.gov.

Respectfully, Thomas Marshall Site Vice President Sequoyah Nuclear Plant Enclosure: Licensee Event Report 50-327/2024-001-00 cc:

NRC Regional Administrator - Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant

Abstract

On August 23, 2024, at 1219 eastern daylight time (EDT), SQN Unit 1 experienced an automatic reactor trip due to a turbine trip. The turbine trip first out had Generator Breaker Trip Turbine Trip and Turbine Trip alarms flashing. It was determined that the generator exciter experienced a loss of excitation due to an open circuit caused by a failure of a stator pole #4 winding.

Operators performed the appropriate actions in response to the reactor trip. All plant safety systems responded as designed. This event did not adversely affect the health and safety of plant personnel or the general public.

The root cause for this event is still under investigation. When the final investigation is complete a supplement will be provided with the identified cause and associated corrective action(s).

Page 5 of 5 B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future The root cause for this event is still under investigation. When the final investigation is complete, a supplement will be provided.

VII. Previous Similar Events at the Same Site LER 50-328/2024-001-00 was submitted for a reactor trip due to an electrical trouble turbine trip.

The cause of the Unit 2 event is under investigation.

VIII. Additional Information There is no additional information.

IX.

Commitments There are no new commitments.