Emergency Diesel Generator (EDG) is a system used during an accident to supply AC power if off-site power is unavailable.
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| | Site | Start date | Title | Description |
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| IR 05000338/2025003 | North Anna | 5 December 2025 | Integrated Inspection Report 05000338/2025003 and 05000339/2025003 and Inspection Report 07200056/2024001 | | | IR 05000324/2025003 | Brunswick | 4 December 2025 | Integrated Inspection Report 05000324/2025003 and 05000325/2025003 | | | IR 05000263/2025003 | Monticello | 2 December 2025 | Integrated Inspection Report 05000263/2025003 | | | IR 05000280/2025003 | Surry | 2 December 2025 | Integrated Inspection Report 05000280/2025003 and 05000281/2025003 | | | IR 05000400/2025003 | Harris | 2 December 2025 | Integrated Inspection Report 05000400/2025003 | | | ML25330A073 | | 1 December 2025 | The Office of the Inspector General for the U.S. Nuclear Regulatory Commission and Defense Nuclear Facilities Safety Board - Semiannual Report to Congress, April 1, 2025 to September 30, 2025 | | | ENS 58054 | South Texas | 21 November 2025 18:08:00 | Automatic Reactor Trip | The following information was provided by the licensee via phone and email:
At 1208 CST on 11/21/2025, with Unit 2 in Mode 1 at 100 percent power, (the) Unit 2 reactor automatically tripped due to a main transformer lockout. The trip was not complex, with all systems responding normally post-trip. One of three essential chillers (chiller 22C) was inoperable at the time of (the) trip due to planned maintenance activities. All other engineered safety feature (ESF) equipment was operable at the time of the event.
Operations responded and stabilized the plant. Decay heat is being removed by steam generator pressure operated relief valves (PORV). There was no impact to Unit 1.
All control rods fully inserted.
Primary pressurizer PORV '655A' opened twice to relieve pressure in response to (the) pressure transient.
(South Texas Project Unit 2) entered Technical Specification 3.8.1.1.e due to a loss of two off-site power sources, `A' and `C' ESF busses.
Upon main turbine trip, throttle valves closed as expected.
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) due to valid actuation of two of the three emergency diesel generators.
There was no impact on the health and safety of the public or plant personnel, and Unit 2 remains at normal operating temperature and normal operating pressure.
The NRC Resident Inspector has been notified.
The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:
Emergency diesel generators '21' and '23' automatically started upon loss of power as expected. Auxiliary feedwater actuated post-trip as expected. Offsite power to ESF busses has been restored. | | ML25307A208 | Calvert Cliffs | 20 November 2025 | Individual Notice for Calvert Cliffs Technical Specification 3.8.1 License Amendment Request | | | Inspection Manual Change Notice 25-033, Table of Contents for Inspection Manual Change Notice 25-033 | | 20 November 2025 | Table of Contents for Inspection Manual Change Notice 25-033 | | | ML25307A199 | Davis Besse | 20 November 2025 | Individual Notice for Davis-Besse Technical Specification 3.8.1 License Amendment Request (FRN) | |
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