05000391/LER-2024-003, Inoperability of Both Trains of Unit 2 Low Head Safety Injection
| ML24193A307 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 07/11/2024 |
| From: | Reneau W Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| WBL-24-029 LER 2024-003-00 | |
| Download: ML24193A307 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3912024003R00 - NRC Website | |
text
1\\14 TENNESSEE VALLEY AUTHORITY Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 WBL-24-029 July 11, 2024 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C. 20555-0001 Watts Bar Nuclear Plant, Unit 2 Facility Operating License No. NPF-96 NRC Docket No. 50-391 10 CFR 50.73
Subject:
Licensee Event Report 391/2024-003-00, lnoperability Of Both Trains Of Unit 2 Low Head Safety Injection Pursuant to the reporting requirements of 10 CFR 50. 73, attached is the subject Licensee Event Report concerning the lnoperability Of Both Trains Of Unit 2 Low Head Safety Injection on May 13, 2024.
There are no new regulatory commitments contained in this letter. Please direct any questions concerning this matter to Jonathan Johnson, WBN Licensing Manager, at jtjohnsonO@tva.gov.
Respectfully, William C. R au Site Vice President Watts Bar Nuclear Plant
U.S. Nuclear Regulatory Commission WBL-24-029 Page 2 July 11, 2024 Enclosure: Tennessee Valley Authority. Watts Bar Nuclear Plant, Unit 2, LER 391/2024-003-00, lnoperability Of Both Trains Of Unit 2 Low Head Safety Injection cc (w/Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Region II
ENCLOSURE Tennessee Valley Authority Watts Bar Nuclear Plant Unit 2 LER 391 /2024-003-00, " lnoperability Of Both Trains Of Unit 2 Low Head Safety Injection" WBL-24-029 E1 of 1
Abstract
At 0917 Eastern Daylight Time (EDT) on May 13, 2024, a control room operator erroneously rendered the "B" train of the Unit 2 residual heat removal (RHR) system inoperable. The inoperability resulted from the operator inappropriately closing the B train RHR heat exchangers outlet flow control valve (2-FCV-74-28). This manipulation occurred while the "A" train of the Unit 2 RHR system was out of service for preplanned maintenance.
RHR serves as the low head safety injection (LHSI) subsystem for the emergency core cooling system (ECCS) and because of this, Unit 2 was without a required train of ECCS from 0917 EDT to 0921 EDT when 2-FCV-74-28 was reopened.
The LHSI subsystem is credited by the analysis for a large break loss of coolant accident at full power.
This event is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D) as an event that could have prevented fulfillment of the safety function of a system needed to mitigate the consequences of an accident.
Page 6 of 6 B. Corrective Actions to Prevent Recurrence or to reduce the probability of similar events occurring in the future The following corrective actions were developed for this event:
- 1. A remedial plan was developed for the involved Control Room Operator (CRO) and will be implemented prior to his return to shift duties.
- 2. Expectations for NUSOs role in upholding the standards contained in OPDP-1, Conduct of Operations will be clarified.
- 3. Modify 2-SI-74-63-A, 18 Month Channel Calibration of Remote Shutdown Control RHR Heat Exchanger A Outlet Flow Loop 2-LPF-74-16, and similar procedures to require a concurrent verification (CV) for manipulation of a controller.
- 4. Require that a pre-job brief be conducted for all operations support activities for maintenance.
VII. Previous Similar Events at the Same Site
None
VIII. Additional Information
None.
IX.
Commitments
None.