05000458/LER-2025-005, For River Bend Station, Unit 1, Containment Unit Coolers Inoperable Due to Compensatory Measures
| ML25293A447 | |
| Person / Time | |
|---|---|
| Site: | River Bend  (NPF-047) |
| Issue date: | 10/20/2025 |
| From: | Mccoy J Entergy Operations |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| RBG-48380 LER 2025-005-00 | |
| Download: ML25293A447 (1) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4582025005R00 - NRC Website | |
text
- ) entergy RBG-48380 October 20, 2025 ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001 Jack McCoy Manager Regulatory and Emergency Planning 225-378-3310 10 CFR 50.73
Subject:
Licensee Event Report 50-458 / 2025-005-00, Containment Unit Coolers Inoperable Due to Compensatory Measures River Bend Station - Unit 1 NRC Docket Nos. 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.
Should you have any questions, please contact Mr. Jack McCoy, Regulatory and Emergency Planning Manager, at 225-378-3310.
Respectfully, Jack McCoy JM/jdb
Enclosure:
cc:
DigrtallysignedbyJack.McCoy ON: cn:Jack McCoy, o=Manager Regulatory and Emergency Preparedness, ou=Entergy/ River Bend,
email=jmccoy1@entergy.com Date: 2025.10.2013:35:51 -05'00' LER 50-458 / 2025-005-00, Containment Unit Coolers Inoperable Due to Compensatory Measures NRC Region IV Regional Administrator - Region IV NRC Senior Resident Inspector - River Bend Station NRC Office of Nuclear Security and Incident Response Entergy Operations, Inc., 5485 U.S. Highway 61 N. St. Francisville, LA 70775
Enclosure RBG-48380 Licensee Event Report 50-458/2025-005-00
Abstract
On August 20, 2025, at 1020 CDT, River Bend Station, Unit 1 (RBS) was operating at 100% power, when it was discovered that previously implemented compensatory measures were determined to have rendered Containment Unit Cooler 'A' (HVR-UC1A) and Containment Unit Cooler 'B' (HVR-UC1B) inoperable.
On August 14, 2025, RBS placed HVR-UC 1 A and HVR-UC 1 B in lockout as a compensatory measure to ensure operability following a Part 21 notification from General Electric. On August 20, 2025, it was discovered that the lockout function would delay the start of a time-delay relay needed for load sequencing in the event of an accident.
The cause of this event was due to inadequate compensatory measures that were established by plant personnel. These compensatory measures would have prevented the containment unit coolers from performing their safety function.
This event is being reported under 10 CFR 50.73 (a)(2)(ii)(B) as any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety, 10 CFR 50.73(a)(2)(v)(C) and 10 CFR 50.73(a)(2)(v)(D) as an event or condition that could have prevented fulfillment of a safety function that is needed to control the release of radioactive material and mitigate the consequences of an accident, and 10 CFR 50.73(a)(2)(i)(B) as an Operation or Condition Prohibited by Technical Specifications.
Event Description
- 2. DOCKET NUMBER YEAR 00458 2025
- 3. LERNUMBER SEQUENTIAL NUMBER 005 REV NO.
00 On August 14, 2025, River Bend Station, Unit 1 (RBS) placed Containment Unit Cooler 'A' (HVR-UC1A) [VA:CLR] and Containment Unit Cooler 'B' (HVR-UC1 B) [VA:CLR] in lockout as a compensatory measure to ensure operability following a Part 21 notification from General Electric.
On August 20,2025, it was discovered that the lockout function would delay the start of a time-delay relay [RL Y] needed for load sequencing in the event of an accident. This condition would prevent the unit coolers from starting within their required sequence following a Loss of Offsite Power.
The compensatory measures included actions to place HVR-UC1A and HVR-UC1 Bin a continuously running state during normal plant operation. In the event of a Loss of Offsite Power, a dedicated operator would be required to reset the lockout pushbuttons for each unit cooler to meet the safety function time requirement associated with the load sequence. Following a review of the compensatory actions on August 20, 2025, it was determined that the compensatory actions were inappropriately applied. The compensatory actions that were implemented would have caused HVR-UC1A and HVR-UC1 B to start up to 10 minutes after the dedicated operator reset the lockout pushbuttons, instead of 10 minutes following a Loss of Offsite Power.
During the time that HVR-UC1A and HVR-UC1 B were in lockout, Technical Specifications (TS) Limiting Condition for Operation 3.6.1.7, Primary Containment Unit Cooler, Condition B was applicable. On August 20, 2025, at 1219 CDT, these compensatory measures were removed.
This event was reported under 10 CFR 50.72(b)(3)(ii)(B) as any event or condition that results in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety, as well as, 10 CFR 50.72(b)(3)(v)(C) and 10 CFR 50.72(b)(3)(v)(D) as an event or condition that could have prevented fulfillment of a safety function that is needed to control the release of radioactive material and mitigate the consequences of an accident and 10 CFR 50.73(a)(2)(i)(B) as an Operation or Condition Prohibited by TS.
Event Cause
The cause of the event was due to multiple ineffective reviews of electrical drawings resulting in Engineering personnel failing to recognize the impact of the compensatory measures on the loading sequence of the containment unit coolers. During review and validation prior to implementation, Operations personnel did not recognize the impact of the compensatory measures. As a result, compensatory measures were implemented which would have prevented the containment unit coolers from performing their safety function.
Safety Assessment
The actual consequences of this event were minimal. A loss of offsite power did not occur during the duration that HVR-UC1A and HVR-UC1 B were inoperable. There were also no radiological impacts. Therefore, there was no actual impact on the health and safety of the public. Page 2 of 3 (04-02-2024)
U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 04/30/2027 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET (See NUREG-1022, R.3 for instruction and guidance for completing this form https:/lwww.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
- 1. FACILITY NAME 050 River Bend Station, Unit 1 052
Corrective Actions
Planned:
- 2. DOCKET NUMBER YEAR 00458 2025
- 3. LERNUMBER SEQUENTIAL NUMBER 005 REV NO.
00 Perform a standards reset with respect to the expectations of independent reviews.
Perform a standards reset with personnel to ensure compliance with procedures that govern pre-job briefs and human performance tools.
Perform management observations during development of operability determinations.
Incorporate operational experience and lessons learned from this event into continual training.
Previous Occurrences
None Energy Industry Identification System (EIIS) codes are identified in the text as [XX]. River Bend equipment codes are identified as (XX). Page 3 of 3