05000296/LER-2025-002, Reactor Core Isolation Cooling Inoperable Due to Failed Ramp Generating Signal Converter
| ML25293A446 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  (DPR-068) |
| Issue date: | 10/20/2025 |
| From: | Komm D Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LER 2025-002-00 | |
| Download: ML25293A446 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2962025002R00 - NRC Website | |
text
Post Office Box 2000, Decatur, Alabama 35609-2000 October 20, 2025 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 3 Renewed Facility Operating License No. DPR-68 NRC Docket No. 50-296
Subject:
Licensee Event Report 50-296/2025-002-00 The enclosed Licensee Event Report provides details of the inoperability of the BFN Unit 3 Reactor Core Isolation Cooling system for a period exceeding the systems Technical Specification (TS) allowed outage time. 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 TS.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact David J. Renn, Nuclear Site Compliance Manager, at (256) 729-2636.
Respectfully, Daniel A. Komm Site Vice President Enclosure: Licensee Event Report 50-296/2025-002 Reactor Core Isolation Cooling Inoperable due to a Failed Ramp Generating Signal Converter 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 Unit 3 Licensee Event Report 50-296/2025-002-00 Reactor Core Isolation Cooling Inoperable due to a Failed Ramp Generating Signal Converter See Enclosed
Abstract
On August 19, 2025, at 1128 Central Daylight Time (CDT), during the performance of 3-SR-3.5.3.3, RCIC System Rated Flow at Normal Operating Pressure, the Reactor Core Isolation Cooling system (RCIC) failed to achieve required flow rate and pump discharge pressure due to an issue with the governor control system. Upon investigation, it was determined that the Unit 3 RCIC Ramp Generating Signal Converter (RGSC) module had failed on July 20, 2025. On August 23, 2025, at approximately 0108 CDT, the Unit 3 RCIC was declared operable following replacement of the RGSC and successful Cold Quick Start Post Maintenance Testing.
The apparent cause of this condition was accumulated stress over time on the operational amplifiers leading to failure of the RGSC. The corrective actions for this condition are to replace the Unit 3 RCIC RGSC, to replace ageing RGSCs and Electro-Governor Magnetic Pickups at the earliest opportunity, and to create new PMs to periodically replace similar components on the Unit 1, 2, and 3 RCIC and High Pressure Coolant Injection systems.
A. Immediate Corrective Actions
The Unit 3 RCIC RGSC was replaced under Work Order 125559901.
B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future The corrective actions for this event are as follows:
- 1. To create new PMs to periodically replace the HPCI and RCIC RGSCs and Electro-Governor Magnetic Pickup (EG-M).
- 2. To replace the following components at the earliest opportunity due to age:
x Unit 1 HPCI EG-M x
Unit 2 RCIC EG-M x
VII. Previous Similar Events at the Same Site
A review of the BFN CAP and Licensee Event Reports for Units 1, 2, and 3 revealed no other instances within the past three years of RCIC inoperability due to RGSC failure.
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.