| ENS 57773 | Turkey Point | 21 June 2025 18:38:00 | Unusual Event - Unit 4 Containment Isolation Failure Due to Bus Lockout | The following information is a summary of the information provided by the licensee via phone and email:
On 6/21/2025, at 1438 EDT, Turkey Point experienced an unplanned reactor trip and a spurious safety injection signal when the '4A' 4 kV bus locked out. An Unusual Event, SU8.1, was declared at 1453 EDT due to two open, motor-operated steam generator sample containment isolation valves not closing on the phase 'A' containment isolation signal due to the loss of power. There were no abnormal parameters that would require a safety injection signal.
Turkey Point unit 3 was unaffected and remains at 100 percent power. Turkey Point unit 4 is stable in mode 3.
The state and one county were notified, and the other county will be notified.
The NRC Resident Inspector was notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
The licensee manually closed the valves due to loss of power to the bus, and they are investigating the cause of the reactor trip.
- * * UPDATE ON 06/21/2025 AT 1639 EDT FROM CHAD HELLMAN TO KAREN COTTON * * *
Turkey Point unit 4 exited the Unusual Event at 1609 EDT.
Notified R2RA (Lara), NRR (Bowman), NSIR (Erlanger), R2DO (Blamey), NRR EO (Felts), IR MOC (Whited), R2 PAO (Gasperson).
Notified DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email).
- * * UPDATE ON 06/21/2025 AT 1835 EDT FROM ADAM ABRAMS TO KAREN COTTON * * *
The following information was provided by the licensee via phone and email:
On June 21, 2025, at 1438 EDT, while Turkey Point Unit 4 was in mode 1 at 100 percent power, the reactor automatically tripped due to lockout of the '4A' 4 kV bus. The cause of the bus lockout is unknown. The trip was complicated with all systems responding normally post-trip, except for containment isolation valves powered from the '4A' 4 kV bus. Operations stabilized the plant in mode 3. Decay heat is removed by discharging steam from the steam generators to atmosphere. Unit 3 is not affected. This event is being reported pursuant to 10 CFR 50.72(b)(2)(iv)(B).
An actuation of the auxiliary feedwater (AFW) system occurred during the reactor trip and safety injection signal. The AFW pumps automatically started as designed when the low steam generator, safety injection, and '4A' 4 kV bus undervoltage signals were received. This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A).
The NRC Resident Inspector has been notified."
Notified R2DO (Blamey). |
| ENS 57769 | Farley | 20 June 2025 01:27:00 | Automatic Reactor Trip and Automatic Actuation of Auxiliary Feedwater System | The following information was provided by the licensee via phone and email:
On June 19, 2025, at 2027 CDT, with Unit 2 in mode 1 at 100 percent power, the reactor automatically tripped due to an `A' steam generator (SG) water level low signal. The low level in the SG was caused by a feedwater control system malfunction. All safety related systems responded normally post-trip. Operations responded and stabilized the plant.
Decay heat is being removed by steam dumps to the main condenser. Farley Unit 1 is not affected.
An automatic actuation of auxiliary feedwater system also occurred, which is an expected response from the reactor trip.
Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) and an eight-hour non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the auxiliary feedwater system.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified. |
| ENS 57734 | Vogtle | 28 May 2025 16:53:00 | Manual Reactor Trip and Auxiliary Feedwater Actuation | The following information was provided by the licensee via phone and email:
At 1253 EDT, on May 28, 2025, with Unit 1 in mode 1 at 100 percent power, the reactor was manually tripped due to a loss of main feedwater pump `A'. The trip was not complex, with all systems responding normally post-trip.
Operations responded and stabilized the plant. Decay heat is being removed by discharging steam through the steam dumps to the main condenser. Units 2, 3, and 4 are not affected. An automatic actuation of auxiliary feedwater (AFW) also occurred. The AFW auto-start is an expected response from the reactor trip.
Due to the reactor protection system actuation while critical, this event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). This event is also being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the auxiliary feedwater system.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
All control rods inserted on the trip. A main feedwater pump lube oil evolution was in progress at the time of the trip. |