05000458/LER-2021-003, Condition Prohibited by Technical Specifications Due to Failure to Perform Breaker Functional Test
| ML21175A038 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 06/24/2021 |
| From: | Karenina Scott Entergy Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RBG-48103 LER 2021-03-00 | |
| Download: ML21175A038 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4582021003R00 - NRC Website | |
text
-~ Entergy RBG-48103 June 24, 2021 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Entergy Operations, Inc.
River Bend Station 5485 U.S. Highway 61N St. Francisville, LA 70775 Tel 225-381-4374 Kent Scott Site Vice President 10 CFR 50.73
Subject:
Licensee Event Report 50-458 / 2021-03-00, "Condition Prohibited by Technical Specifications due to failure to perform Breaker Functional Test" River Bend Station - Unit 1 NRC Docket No. 50-458 Renewed Facility Operating License No. NPF-47 In accordance with 10 CFR 50.73, enclosed is the subject Licensee Event Report. This document contains no commitments. If you have any questions, please contact Mr. Tim Schenk at 225-381-4177.
Respectfully, (
KCS/dmw
Enclosure:
Q Licensee Event Report 50-458 / 2021-03-00, "Condition Prohibited by Technical Specifications due to failure to perform Breaker Functional Test" cc:
NRC Regional Administrator - Region IV NRC Project Manager - River Bend Station NRC Senior Resident Inspector - River Bend Station Louisiana Department of Environmental Quality Public Utility Commission of Texas
Enclosure RBG-48103 Licensee Event Report 50-458 I 2021-03-00, "Condition Prohibited by Technical Specifications due to failure to perform Breaker Functional Test"
Abstract
On April 08, 2021 at 09:26 CDT, River Bend Station was operating at 65% reactor power. At that time, while alternating divisions of Control Building Chilled Water from Division 1 to Division 2, Control Building Chiller D (HVK-CHL 10) failed to start. Control Building Chilled Water was restored to service in accordance with station procedures at 09:38 CDT.
HVK-CHL 1 D did not start because the supply breaker position switch contacts did not connect. A required breaker functional test had not been performed to verify proper operation after HVK-CHL 1 D supply breaker was racked to the connect position following tagout restoration on March 30, 2021. This caused HVK-CHL 1 D to be aligned as the standby chiller while it was not operable.
The cause of the event was a gap in human performance. Corrective Actions include procedure revisions and departmental briefings to ensure awareness and to avoid recurrence.
EVENT DESCRIPTION
SEQUENTIAL NUMBER 003 REV NO.
00 On April 08, 2021 at 09:26 CDT, River Bend Station was operating at 65% reactor power. At that time, Control Building Chiller D (HVK-CHL 1 D) failed to start while alternating divisions of Control Building Chilled Water (KM). Control Building Chilled Water was restored to service in accordance with station procedures at 09:38 CDT.
A required breaker functional test, which would have verified HVK-CHL 1 D (CHU) operability, had not been performed when HVK-CHL 1 D supply breaker was racked to the connect position following tagout restoration. This oversight resulted in equipment required by Technical Specifications to be placed in standby without being verified Operable. This condition existed from March 30,2021 at 15:32 CDT until this event occurred on April 08,2021. Technical Specification 3.7.7 Control Building Air Conditioning (CBAC) System 72-hour allowed outage time was exceeded and the required Action to be in Mode 3 within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> was not met.
Timeline of events:
03/12/2021 07:39 - HVK-CHL 1 D supply breaker tag removed and racked to the connect position.
03/30/2021 15:32 - HVK-CHL 1D was placed in standby 04/08/2021 09:26 - HVK-CHL 1 D failed to start during Divisional Swap 04/28/2021 21 :23 - Discovery date - Past Operability Evaluation Complete.
This report is being made pursuant to 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications.
SAFETY ASSESSMENT
There were no actual nuclear or radiological safety consequences due to this event. This event was of minimal significance to the health and safety of the public. The Control Building Chilled Water System was procedurally restored, and control building temperature margins were not challenged.
EVENT CAUSE
This event was caused by a gap in human performance. Senior Reactor Operators (SRO) failed to ensure completion of the required functional test due to perceived time pressure. The SRO authorizing the tagout assumed the breaker functional would be added to the Limiting Condition of Operability (LCO) when the tagout was removed. The SRO authorizing the tagout for removal assumed the breaker functional was added to the LCO already. Neither SRO validated their assumptions.
All other equipment associated with the tagout was checked and no additional missed breaker functional tests were discovered. HVK-CHL 1 D was successfully tested following an adjustment to the supply breaker.
CORRECTIVE ACTIONS
Operations procedure guidance will be revised to require adding the breaker functional test to the LCO separate from the tagout when the tag is hung. The intent is to standardize when every SRO adds required breaker functionals to LCOs.
(Completion tracked by Corrective Action)
An Operations Departmental briefing on this event will be developed and distributed. The intent is to ensure department personnel are aware of what occurred so it can be avoided in the future. (Completion tracked by Corrective Action)
PREVIOUS SIMILAR EVENTS
None