Event Notification Report for April 20, 2025

EN Revision Imported Date: 5/9/2025

EN Revision Text: EMERGENCY CORE COOLING SYSTEM (ECCS) ACCUMULATORS INOPERABLE

The following information was provided by the licensee via phone and email:

"At 0028 EDT on 4/20/2025, it was discovered that all trains of the ECCS accumulators were simultaneously inoperable. Therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v). The safety function was restored at 0028 on 04/20/2025 and all required trains have been declared operable. There was no impact to the other unit.

"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:

The sample lines for each accumulator cold leg were open for inspection, which crossties the cold leg accumulator gas spaces. Upon discovery of this condition, the sample lines were subsequently closed, and the accumulators were declared operable.

* * * RETRACTION ON 05/08/2025 AT 1716 EDT FROM HUNTER LAUSTED TO JORDAN WINGATE * * *

The following information was provided by the licensee via phone and email:

"This report retracts the 8-hour notification made on April 20, 2025, for NRC Event Number 57673.

"NRC Event Report Number 57673 describes a condition at McGuire Nuclear Station Unit 1 where all trains of ECCS accumulators were declared inoperable. This condition was reported in accordance with 10CFR 50.72(b)(3)(v)(D) as a condition that could have prevented the fulfillment of a safety function to mitigate the consequences of an accident. Upon further engineering review, all four ECCS accumulators were operable and would have performed their specified safety functions with all four nuclear sampling system (inside containment) isolation valves open, concurrent with the most limiting large break loss of coolant accident and worst-case single failure. Therefore, this event is not reportable as an event or condition that could have prevented the fulfillment of a safety function and is hereby retracted.

"There was no impact on the health and safety of the public or plant personnel.

"The NRC Resident Inspector has been notified."

Notified R2DO (Franke)

AGREEMENT STATE REPORT - LOST OR STOLEN DENSITY GAUGE

The following report was received by the California Radiation Control Program (the Agency) via email:

"On April 21, 2025, the licensee's radiation safety officer (RSO) contacted the Agency to report the theft of a Troxler 3440 moisture density gauge, serial number 31320. The theft occurred on April 20, 2025, at 2240 PDT at a jobsite in Los Angeles, California. The Los Angeles Police Department was contacted, and a police report was filed. The Troxler gauge contains an 8 mCi cesium-137 sealed source and a 40 mCi americium-241/Be sealed source. The investigation is ongoing."

California 5010 Number: 042125

THIS MATERIAL EVENT CONTAINS A 'Less than Cat 3' LEVEL OF RADIOACTIVE MATERIAL

Sources that are "Less than IAEA Category 3 sources," are either sources that are very unlikely to cause permanent injury to individuals or contain a very small amount of radioactive material that would not cause any permanent injury. Some of these sources, such as moisture density gauges or thickness gauges that are Category 4, the amount of unshielded radioactive material, if not safely managed or securely protected, could possibly - although it is unlikely - temporarily injure someone who handled it or were otherwise in contact with it, or who were close to it for a period of many weeks. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf