05000260/LER-2024-002, High Pressure Coolant Injection Inoperable Due to Rupture Disc Failure and Resulting System Isolation
| ML24141A246 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/20/2024 |
| From: | Sivaraman M Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LER 2024-002-00 | |
| Download: ML24141A246 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2602024002R00 - NRC Website | |
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Post Office Box 2000, Decatur, Alabama 35609-2000 May 20, 2024 10 CFR 50.73 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001
Subject:
Browns Ferry Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-52 NRC Docket No. 50-260 Licensee Event Report 50-260/2024-002 High Pressure Coolant Injection Inoperable due to Rupture Disc Failure and Resulting System Isolation The enclosed Licensee Event Report provides details of an isolation of the High Pressure Coolant Injection (HPCI) system on Browns Ferry Nuclear Plant, Unit 2. 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)(v)(D), as any event or condition which could have prevented the fulfillment of the safety function of a system that is needed to mitigate the consequences of an accident.
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 Licensing Manager, at (256) 729-2636.
Respectfully, Manu Sivaraman Site Vice President Enclosure: Licensee Event Report 50-260/2024-002 High Pressure Coolant Injection Inoperable due to Rupture Disc Failure and Resulting System Isolation cc (w/ Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Browns Ferry Nuclear Plant NRC Project Manager - Browns Ferry Nuclear Plant
U.S. Nuclear Regulatory Commission Page 2 May 20, 2024 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 50-260/2024-002-00 HPCI Inoperable due to Rupture Disc Failure and Resulting System Isolation See Enclosed
Abstract
On March 19, 2024, at 1030 Central Daylight Time (CDT), during performance of 2-SR-3.5.1.7 High Pressure Coolant Injection (HPCI) Flowrate at Rated Reactor Pressure, after operating the Unit 2 HPCI system for approximately thirty-seven minutes at rated pressure and flow, BFN Unit 2 received indications of high rupture disc pressure, HPCI Turbine trip, and HPCI isolation. Operations personnel verified HPCI isolated as expected, declared HPCI inoperable, verified BFN Unit 2 Reactor Core Isolation Cooling (RCIC) operability, and entered 2-AOI-64-2B for Isolation. On March 19, 2024, at 1719 CDT, Event Notification 57036 was made to the NRC. BFN Unit 2 remained in Technical Specification (TS) Limiting Condition for Operation (LCO) 3.5.1 until the rupture disc was repaired and the HPCI system was declared operable at 1051 CDT on March 25, 2024.
The cause of the event was leakage through the HPCI inner rupture disc due to fatigue failure from cyclic temperature, pressure, and vacuum loading. The corrective action taken was to replace the Unit 2 HPCI rupture discs. Additionally, a design change to install reverse-acting rupture discs on BFN Unit 1, 2, and 3 HPCI and RCIC systems will be implemented.
Page 6 of 6 C. For failure that rendered a train of a safety system inoperable, estimate of the elapsed time from discovery of the failure until the train was returned to service The BFN Unit 2 HPCI system was returned to operability on March 25, 2024, approximately six days after discovery on March 19, 2024.
VI.
Corrective Actions
Corrective Actions are being managed by the TVAs Corrective Action Program (CAP) under Condition Report (CR) 1917980.
A. Immediate Corrective Actions
HPCI rupture discs 2-RPD-073-0729 and 2-RPD-073-0730 were replaced.
B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future A design change will be implemented to install reverse-acting rupture discs on BFN Unit 1, 2, and 3 HPCI and RCIC systems.
VII. Previous Similar Events at the Same Site
A review of the BFN CAP and Licensee Event Reports (LERs) for Units 1, 2, and 3 revealed no rupture disc failures resulting in the inoperability of BFN HPCI systems for the last three years.
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.