05000260/LER-2025-001-01, Reactor Scram Due to Low Electro-Hydraulic Control Pressure
| ML25252A080 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 09/09/2025 |
| From: | Komm D Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LER 2025-001-01 | |
| Download: ML25252A080 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation |
| 2602025001R01 - NRC Website | |
text
Post Office Box 2000, Decatur, Alabama 35609-2000 September 9, 2025 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Browns Ferry Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-52 NRC Docket No. 50-260
Subject:
Licensee Event Report 50-260/2025-001-01
Reference:
Letter from TVA to NRC, License Event Report 50-260/2025-001-00, dated July 10, 2025 (ML25191A210)
The enclosed Licensee Event Report provides details of a SCRAM due to low electro-hydraulic control pressure on Browns Ferry Nuclear Plant, Unit 2, followed by a second automatic Reactor Protection System actuation due to a low reactor water level transient caused by manually opening and closing a main steam relief valve. The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.73(a)(2)(iv)(A), as any event or condition that resulted in a manual or automatic actuation of the Reactor Protection System and Primary Containment Isolation System. Revision 1 to this report includes information from the cause evaluation that was not previously reported.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact David J. Renn, Site Compliance Manager, at (256) 729-2636.
Respectfully, Daniel A. Komm Site Vice President Enclosure: Licensee Event Report 50-260/2025-001 Reactor SCRAM due to Low Electro-Hydraulic Control Pressure
U.S. Nuclear Regulatory Commission Page 2 September 9, 2025 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 2 Licensee Event Report 50-260/2025-001-01 Reactor SCRAM due to Low Electro-Hydraulic Control Pressure See Enclosed
Abstract
On May 12, 2025, at 1353 Central Standard Time (CST), Browns Ferry Nuclear Plant, Unit 2, experienced a significant electro-hydraulic control (EHC) leak, resulting in a turbine trip and automatic reactor SCRAM on low EHC pressure. The trip was not complex with all systems responding normally post trip except for the turbine bypass valves, which subsequently failed closed due to loss of EHC pressure. At 1407 CST, with Unit 2 in Mode 3, there was a second automatic RPS actuation due to a low reactor water level transient caused by manually opening and closing a main steam relief valve. Event Notification 57705 was made to the Nuclear Regulatory Commission (NRC) Operations Center on May 12, 2025, at 1731 CST.
It was documented that three broken mounting cap screws were found. Failure analysis was completed on the broken cap screws and determined that the cap screws failed due to hydrogen embrittlement. Investigation into the source of hydrogen intrusion determined that there were two potential sources: environmental intrusion and pickling during the manufacturing process.
The Tennessee Valley Authority is submitting this report in accordance with Title 10 of the Code of Federal Regulations (10 CFR) 50.73(a)(2)(iv)(A), as any event or condition that resulted in manual or automatic actuation of the Reactor Protection System and the Primary Containment Isolation System.
VII. Previous Similar Events at the Same Site
There were no previous similar events found at the site.
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].