The following information was provided by the licensee via phone and email:
At 1535 CDT on 10/22/2025, with Unit 1 in mode 1 at 86 percent power, the reactor was manually tripped due to low turbine electro-hydraulic control (EHC) oil system reservoir level, caused by a leak developing in the heater bay. The trip was not complex, with all systems responding normally post-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).
Operations responded using the emergency operating procedure for reactor pressure vessel control and stabilized the plant in mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves, which have a separate EHC oil system.
There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified.