ENS 57880
ENS Event | |
|---|---|
15:20 Aug 20, 2025 | |
| Title | Inoperable Containment Unit Coolers |
| Event Description | The following information was provided by the licensee via phone and email:
On August 20, 2025, at 1020 CDT, River Bend Station (RBS) was operating at 100 percent reactor power when it was discovered that previously implemented enhancement 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-UC1A' and 'HVR-UC1B' in lockout as a compensatory measure to enhance 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 relay needed for load sequencing in the event of an accident. This condition would prevent the unit coolers from starting within their required sequence timing following a loss of offsite power. 'HVR-UC1A' and 'HVR-UC1B' were declared inoperable. By 1219 CDT, these compensatory measures were no longer in place. This event is being 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. The NRC Resident Inspector has been notified. |
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident | |
| Time - Person (Reporting Time:+1.73 h0.0721 days <br />0.0103 weeks <br />0.00237 months <br />) | |
| Opened: | Jason Shidaker 17:04 Aug 20, 2025 |
| NRC Officer: | Tenisha Meadows |
| Last Updated: | Aug 20, 2025 |
| 57880 - NRC Website
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