Event Notification Report for August 20, 2025
U.S. Nuclear Regulatory Commission
Operations Center
EVENT REPORTS FOR
08/19/2025 - 08/20/2025
Power Reactor
Event Number: 57879
Facility: Cook
Region: 3 State: MI
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Craig Wohlgamuth
HQ OPS Officer: Brian P. Smith
Region: 3 State: MI
Unit: [1] [2] []
RX Type: [1] W-4-LP,[2] W-4-LP
NRC Notified By: Craig Wohlgamuth
HQ OPS Officer: Brian P. Smith
Notification Date: 08/20/2025
Notification Time: 12:43 [ET]
Event Date: 08/20/2025
Event Time: 08:11 [EDT]
Last Update Date: 08/20/2025
Notification Time: 12:43 [ET]
Event Date: 08/20/2025
Event Time: 08:11 [EDT]
Last Update Date: 08/20/2025
Emergency Class: Non Emergency
10 CFR Section:
26.719 - Fitness For Duty
10 CFR Section:
26.719 - Fitness For Duty
Person (Organization):
Ruiz, Robert (R3DO)
FFD Group, (EMAIL)
Ruiz, Robert (R3DO)
FFD Group, (EMAIL)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
FITNESS-FOR-DUTY
The following information was provided by the licensee via phone and email:
"A non-licensed employee had a confirmed positive for alcohol during a random fitness-for-duty [test]. The employee's access to the plant has been terminated."
The NRC Resident Inspector has been notified.
The following information was provided by the licensee via phone and email:
"A non-licensed employee had a confirmed positive for alcohol during a random fitness-for-duty [test]. The employee's access to the plant has been terminated."
The NRC Resident Inspector has been notified.
Power Reactor
Event Number: 57880
Facility: River Bend
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Jason Shidaker
HQ OPS Officer: Tenisha Meadows
Region: 4 State: LA
Unit: [1] [] []
RX Type: [1] GE-6
NRC Notified By: Jason Shidaker
HQ OPS Officer: Tenisha Meadows
Notification Date: 08/20/2025
Notification Time: 17:04 [ET]
Event Date: 08/20/2025
Event Time: 10:20 [CDT]
Last Update Date: 08/20/2025
Notification Time: 17:04 [ET]
Event Date: 08/20/2025
Event Time: 10:20 [CDT]
Last Update Date: 08/20/2025
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(ii)(B) - Unanalyzed Condition 50.72(b)(3)(v)(C) - Pot Uncntrl Rad Rel 50.72(b)(3)(v)(D) - Accident Mitigation
10 CFR Section:
50.72(b)(3)(ii)(B) - Unanalyzed Condition 50.72(b)(3)(v)(C) - Pot Uncntrl Rad Rel 50.72(b)(3)(v)(D) - Accident Mitigation
Person (Organization):
Dodson, Doug (R4DO)
Dodson, Doug (R4DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 1 | N | Y | 100 | Power Operation | 100 | Power Operation |
INOPERABLE CONTAINMENT UNIT COOLERS
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."
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."
Power Reactor
Event Number: 57881
Facility: Fermi
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Robert Hart
HQ OPS Officer: Robert A. Thompson
Region: 3 State: MI
Unit: [2] [] []
RX Type: [2] GE-4
NRC Notified By: Robert Hart
HQ OPS Officer: Robert A. Thompson
Notification Date: 08/21/2025
Notification Time: 02:23 [ET]
Event Date: 08/20/2025
Event Time: 23:08 [EDT]
Last Update Date: 08/21/2025
Notification Time: 02:23 [ET]
Event Date: 08/20/2025
Event Time: 23:08 [EDT]
Last Update Date: 08/21/2025
Emergency Class: Non Emergency
10 CFR Section:
50.72(b)(3)(xiii) - Loss Comm/Asmt/Response
10 CFR Section:
50.72(b)(3)(xiii) - Loss Comm/Asmt/Response
Person (Organization):
Ruiz, Robert (R3DO)
Ruiz, Robert (R3DO)
| Unit | SCRAM Code | RX Crit | Initial PWR | Initial RX Mode | Current PWR | Current RX Mode |
|---|---|---|---|---|---|---|
| 2 | N | Y | 100 | Power Operation | 100 | Power Operation |
MAJOR LOSS OF EMERGENCY ASSESMENT CAPABILITY
The following information was provided by the licensee via phone and email:
"On 08/20/2025 at 2308 EDT, the Fermi 2 active seismic monitoring system provided indication of a potential seismic activity event. Plant abnormal procedures were entered, and compensatory measures were met and remain in place. Neither the United States Geological Survey (USGS) nor the next closest nuclear power plant could confirm/validate the readings obtained at Fermi. The seismic monitoring system was declared inoperable to validate the calibration of the system. Fermi 2 has two active seismic monitors: one on the reactor pressure vessel pedestal and one in the high pressure core injection (HPCI) room. Only the HPCI room seismic monitor was declared inoperable. The HPCI room accelerometer is the sole trigger for the seismic recording system (which outputs peak accelerations experienced during a seismic event) and the associated control room alarm. This is used in assessment of the magnitude of an earthquake for emergency action level HU 2.1.
The loss of the active seismic monitoring system is reportable within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii).
No seismic activity has been felt on-site, and the USGS recorded no seismic activity in the area.
The NRC Resident Inspector has been notified.
An alternative means of monitoring seismic event entry is still available per the emergency plan via USGS.
The following information was provided by the licensee via phone and email:
"On 08/20/2025 at 2308 EDT, the Fermi 2 active seismic monitoring system provided indication of a potential seismic activity event. Plant abnormal procedures were entered, and compensatory measures were met and remain in place. Neither the United States Geological Survey (USGS) nor the next closest nuclear power plant could confirm/validate the readings obtained at Fermi. The seismic monitoring system was declared inoperable to validate the calibration of the system. Fermi 2 has two active seismic monitors: one on the reactor pressure vessel pedestal and one in the high pressure core injection (HPCI) room. Only the HPCI room seismic monitor was declared inoperable. The HPCI room accelerometer is the sole trigger for the seismic recording system (which outputs peak accelerations experienced during a seismic event) and the associated control room alarm. This is used in assessment of the magnitude of an earthquake for emergency action level HU 2.1.
The loss of the active seismic monitoring system is reportable within 8 hours of discovery in accordance with 10 CFR 50.72(b)(3)(xiii).
No seismic activity has been felt on-site, and the USGS recorded no seismic activity in the area.
The NRC Resident Inspector has been notified.
An alternative means of monitoring seismic event entry is still available per the emergency plan via USGS.