ENS 58148
ENS Event | |
|---|---|
05:38 Feb 4, 2026 | |
| Title | |
| Event Description | The following information was provided by the licensee via phone and email:
On February 3, 2026, at 2338 CST, River Bend Station (RBS) was operating at 100 percent reactor power when the standby service water pump `C' (SWP-P2C) faulted, tripped, and locked out during the performance of a routine surveillance. The pump fault caused E22-ACB04, the normal division III 4.16 KV bus supply breaker, to trip and lock out. The division Ill emergency diesel generator (EDG) started as designed and powered the division III 4.16 KV bus. There are no signs of fire. The cause of the SWP-P2C fault is still under investigation. The trip of E22-ACB04 resulted in the inability to meet [surveillance requirement] SR 3.8.9.1 forcing entry into [limiting condition for operation] LCO 3.8.9 required action 'E.1' and declaring the [high pressure core spray] HPCS system inoperable. This event is being reported under 10 CFR 50.72(b)(3)(iv)(A) as an event or condition that results in valid actuation of emergency AC electrical power systems and 10 CFR 50.72(b)(3)(v)(D) as an event or condition that at the time of discovery could have prevented the fulfillment of a safety function. The NRC Resident Inspector has been notified.
This event was initially reported under 10 CFR 50.72(b)(3)(iv)(A) as an event or condition that results in a valid actuation of emergency AC electrical power systems and 10 CFR 50.72(b)(3)(v) as an event or condition that at the time of discovery could have prevented the fulfillment of a safety function. During subsequent investigation, it was determined that the trip of E22-ACB04 did not result in the inability to meet SR 3.8.9.1 which forced entry into LCO 3.8.9 required action 'E.1'. As a result, it has been determined that the HPCS system remained operable. Therefore, this condition is not reportable as an event or condition that at the time of discovery could have prevented the fulfillment of a safety function. However, this event remains reportable as an event or condition that results in a valid actuation of emergency AC electrical power systems. The NRC Resident Inspector has been notified. Notified R4DO (Dodson) |
| Where | |
|---|---|
River Bend  Louisiana (NRC Region 4) | |
| Reporting | |
| 10 CFR 50.72(b)(3)(iv)(A), System Actuation | |
| Time - Person (Reporting Time:+1.52 h0.0633 days <br />0.00905 weeks <br />0.00208 months <br />) | |
| Opened: | Terry Blanchard 07:09 Feb 4, 2026 |
| NRC Officer: | Josue Ramirez |
| Last Updated: | Feb 12, 2026 |
| 58148 - NRC Website
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Unit 1 | |
|---|---|
| Reactor critical | Critical |
| Scram | No |
| Before | Power Operation (100 %) |
| After | Power Operation (100 %) |