05000327/LER-2025-001, Manual Reactor Trip Due to Reboot of the Distributed Control System and Lowering Steam Generator Levels
| ML25233A210 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/21/2025 |
| From: | Michael K Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LER 2025-001-00 | |
| Download: ML25233A210 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(b)(3)(iv)(A) |
| 3272025001R00 - NRC Website | |
text
Sequoyah Nuclear Plant, Post Office Box 2000, Soddy Daisy, Tennessee 37384 August 21, 2025 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 50-327/2025-001-00, Manual Reactor Trip due to Reboot of the Distributed Control System and Lowering Steam Generator Levels The enclosed licensee event report provides details concerning a manual reactor trip due to a reboot of the Distributed Controls System and lowering steam generator water levels. This report is being submitted in accordance with 10 CFR 50.73(b)(3)(iv)(A) as an event that resulted in actuation of the Reactor Protection System and Auxiliary Feedwater System. A supplement to this LER will be submitted following completion of the associated 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 Compliance Manager, at (423) 843-8129 or rmedina4@tva.gov.
Respectfully, Kevin Michael Site Vice President Sequoyah Nuclear Plant Enclosure: Licensee Event Report 50-327/2025-001-00 cc:
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Sequoyah Nuclear Plant
Abstract
On June 24, 2025, at 0014 eastern daylight time (EDT), SQN main control room operators manually tripped Unit 1 due to an apparent failure of the Distributed Control System. Dual Control Processor (CP), S110CP, rebooted resulting in a loss of secondary plant control. Unit 1 was manually tripped due to lowering steam generator water levels. 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 cause for this event is still being evaluated. When the final evaluation is complete, a supplement will be provided with the identified cause and associated corrective action(s). Page 5 of 5
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.