05000296/LER-2022-003-01, Pressure Boundary Leak on Residual Heat Removal System Low Pressure Coolant Injection Test Line Due to Fatigue Failure
| ML23212B015 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/31/2023 |
| From: | Sivaraman M Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| LER 2022-003-01 | |
| Download: ML23212B015 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded |
| 2962022003R01 - NRC Website | |
text
Post Office Box 2000, Decatur, Alabama 35609-2000 July 31, 2023 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 50-296/2022-003-01
Reference:
- 1. Non-Emergency Event Notification 56257 - Degraded Condition Discovered on Shutdown Cooling Test Line
- 2. Letter from TVA to NRC, Licensee Event Report 50-296/2022-003-00, dated January 31, 2023 (ML23031A357)
The enclosed Licensee Event Report provides details of a pressure boundary leak on Browns Ferry Nuclear Plant, Unit 3. 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)(i)(B), as any operation or condition which was prohibited by the plants Technical Specifications; and 10 CFR 50.73(a)(2)(ii)(A), as any event or condition that resulted in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded.
There are no new regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Michael W. Oliver, Acting Nuclear Site Licensing Manager, at (256) 337-6803.
Respectfully, Manu Sivaraman Site Vice President Enclosure: Licensee Event Report 50-296/2022-003 Pressure Boundary Leak on Residual Heat Removal System Low Pressure Coolant Injection Test Line due to Fatigue Failure
U.S. Nuclear Regulatory Commission Page 2 July 31, 2023 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 3 July 31, 2023 MWO:BJC Enclosure bcc (w/ Enclosure):
K. S. Adams J. Barstow D. G. Bost M. B. Bruce C. C. Chandler D. E. Charlton D. M. Delk R. E. Detwiler K. D. Hulvey J. T. Johnson R. J. Krigelman E. Q. Leonard R. Medina M. W. Oliver J. L. Paul J. Quinn M. Rasmussen T. S. Rausch D. K. Riggs S. L. Rymer M. Sivaraman G. R. Williams J. A. Yarbrough ECM
ENCLOSURE Browns Ferry Nuclear Plant Unit 3 Licensee Event Report 50-296/2022-003-01 Pressure Boundary Leak on Residual Heat Removal System Low Pressure Coolant Injection Test Line due to Fatigue Failure See Enclosed
Abstract
On December 2, 2022, at 2330 Central Standard Time (CST), during a drywell entry for leak identification, BFN Engineering personnel discovered a through-wall piping leak on a test line between the two Residual Heat Removal Shutdown Cooling test line isolation valves. On December 3, 2022, at 1000, it was determined that this test line was classified as American Society of Mechanical Engineers Code Class 1 piping and constitutes part of the BFN, Unit 3 Reactor Coolant System pressure boundary. Operations personnel maintained BFN, Unit 3 in Mode 4 or 5 until the leak was repaired. On December 3, 2022, at 1205 CST, eight-hour Event Notification 56257 was made to the NRC.
The test line was cut and capped. The POE for this event determined that the LPCI mode of the BFN, Unit 3 RHR system can still meet the required LPCI flow to the reactor pressure vessel in the worse-case scenario of a small break LOCA for the duration of the mission time. During this time the HPCI system, both loops of the Core Spray system, and all ADS valves remained operable when required, aside from periods of planned maintenance and testing, and were available to provide coolant flow to the core during an emergency.
The root cause of this event was that the small bore piping was not analyzed for vulnerability of fatigue failure due to operational or resonance vibration. Corrective actions are to implement Engineering Changes that will result in bounded life cycles for all levels of vibrational stress that the piping will experience; and to implement additional actions, for U3 systems where failure of small bore branch piping would cause a unit shutdown or loss of RCS boundary, to either modify operating ranges of the system and/or to modify the piping assembly.
VIII. Additional Information
There is no additional information.
IX.
Commitments
There are no new commitments.