05000391/LER-2025-001, Loss of the Control Room Emergency Air Temperature Control System Due to Chiller Valve Malfunction
| ML25021A128 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 01/21/2025 |
| From: | Reneau W Tennessee Valley Authority |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| WBL-25-004 LER 2025-001-00 | |
| Download: ML25021A128 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3912025001R00 - NRC Website | |
text
1\\'4 TENNESSEE VALLEY AUTHORITY Tennessee Valley Authority, Post Office Box 2000, Spring City, Tennessee 37381 WBL-25-004 January 21, 2025 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 391/2025-001-00, Loss of The Control Room Emergency Air Temperature Control System Due to Chiller Valve Malfunction Pursuant to the reporting requirements of 10 CFR 50.73, attached is the subject Licensee Event Report concerning the Loss of The Control Room Emergency Air Temperature Control System Due to Chiller Valve Malfunction for Watts Bar Nuclear Plant, Unit 2, which occurred on November 22, 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,
~~
Site Vice PresidJoL__
Watts Bar Nuclear Plant
U.S. Nuclear Regulatory Commission WBL-25-004 Page 2 January 21, 2025 Enclosure: LER 391/2025-001-00, Loss of The Control Room Emergency Air Temperature Control System Due to Chiller Valve Malfunction cc (w/Enclosure):
NRC Regional Administrator - Region II NRC Senior Resident Inspector - Watts Bar Nuclear Plant NRC Project Manager - Region II
WBL-25-001 E1 of 1 ENCLOSURE Tennessee Valley Authority Watts Bar Nuclear Plant Unit 2 LER 391/2025-001-00, Loss of The Control Room Emergency Air Temperature Control System Due to Chiller Valve Malfunction
Abstract
On November 22, 2024 at 1937 EST, with Unit 1 defueled and Unit 2 at 100% rated thermal power, it was discovered that both trains of the Control Room Emergency Air Temperature Control System (CREATCS) were simultaneously inoperable. This condition occurred when the B-B Main Control Room (MCR) chiller tripped on high gas discharge pressure due to a malfunctioning automatic water temperature control valve (TCV) while the A train of CREATCS had been previously declared inoperable. The B train of CREATCS was later restored at 0130 EST on November 23, 2024 following implementation of compensatory measures that included manually controlling cooling water to the B-B MCR chiller. The applicable technical specification (TS) limiting conditions for operability (LCO) were entered for less than six hours as a result.
This condition is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented fulfillment of a safety function needed to mitigate the consequences of an accident.
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Commitments
None.