Event Notification Report for June 18, 2025
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
06/17/2025 - 06/18/2025
EVENT NUMBERS
57767
57767
Power Reactor
Event Number: 57767
Facility: River Bend
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Casey Colcough
HQ OPS Officer: Ernest West
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Casey Colcough
HQ OPS Officer: Ernest West
Notification Date: 06/18/2025
Notification Time: 12:26 [ET]
Event Date: 06/18/2025
Event Time: 05:53 [CDT]
Last Update Date: 06/18/2025
Notification Time: 12:26 [ET]
Event Date: 06/18/2025
Event Time: 05:53 [CDT]
Last Update Date: 06/18/2025
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(v)(D) - Accident Mitigation 50.72(b)(3)(v)(A) - Pot Unable To Safe S/D
10 CFR Section:
50.72(b)(3)(v)(D) - Accident Mitigation 50.72(b)(3)(v)(A) - Pot Unable To Safe S/D
Person (Organization):
Drake, James (R4DO)
Drake, James (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 90 | Power Operation |
TURBINE CONTROL VALVE 3 MALFUNCTION
The following information was provided by the licensee via phone and email:
"On June 18, 2025, at 0553 CDT, River Bend Station (RBS) was operating at 100 percent reactor power when turbine control valve 3 (CV3) closed, causing both turbine bypass valves to open. Reactor power was lowered to approximately 95 percent and the bypass valves closed. At 0646 CDT, CV3 was observed opening and all other turbine control valves intermittently changing position causing the bypass valves to open again. Reactor power was lowered to 90 percent and the bypass valves closed. The bypass valves were open for approximately one minute for each of the two occurrences.
"With the bypass valves open, technical specification (TS) required instrumentation that utilize turbine first stage pressure were declared inoperable. The following instrumentation functions were declared inoperable: Reactor protection system - turbine stop valve closure and turbine control valve fast closure, trip oil pressure-low. Control rod block instrumentation - rod withdrawal limiter. End of cycle recirculation pump trip instrumentation - turbine stop valve closure and turbine control valve fast closure, trip oil pressure-low.
"Reactor power is currently at 90 percent. CV3 and the bypass valves are closed. All limiting condition of operation (LCO) conditions that were entered as a result of this event have been exited. All plant parameters are stable. Troubleshooting efforts to determine the cause of the CV3 malfunction are ongoing. The highest reactor pressure observed during this event was 1071 psig.
"This event is being reported under 10 CFR 50.72(b)(3)(v) as an event or condition that could have prevented fulfillment of a safety function due to inoperability of both divisions of TS required instrumentation functions.
"The NRC Resident Inspector has been notified."
The following information was provided by the licensee via phone and email:
"On June 18, 2025, at 0553 CDT, River Bend Station (RBS) was operating at 100 percent reactor power when turbine control valve 3 (CV3) closed, causing both turbine bypass valves to open. Reactor power was lowered to approximately 95 percent and the bypass valves closed. At 0646 CDT, CV3 was observed opening and all other turbine control valves intermittently changing position causing the bypass valves to open again. Reactor power was lowered to 90 percent and the bypass valves closed. The bypass valves were open for approximately one minute for each of the two occurrences.
"With the bypass valves open, technical specification (TS) required instrumentation that utilize turbine first stage pressure were declared inoperable. The following instrumentation functions were declared inoperable: Reactor protection system - turbine stop valve closure and turbine control valve fast closure, trip oil pressure-low. Control rod block instrumentation - rod withdrawal limiter. End of cycle recirculation pump trip instrumentation - turbine stop valve closure and turbine control valve fast closure, trip oil pressure-low.
"Reactor power is currently at 90 percent. CV3 and the bypass valves are closed. All limiting condition of operation (LCO) conditions that were entered as a result of this event have been exited. All plant parameters are stable. Troubleshooting efforts to determine the cause of the CV3 malfunction are ongoing. The highest reactor pressure observed during this event was 1071 psig.
"This event is being reported under 10 CFR 50.72(b)(3)(v) as an event or condition that could have prevented fulfillment of a safety function due to inoperability of both divisions of TS required instrumentation functions.
"The NRC Resident Inspector has been notified."