Event Notification Report for June 02, 2025

AGREEMENT STATE REPORT - STOLEN GAUGE

The following information was provided by the California Department of Public Health, Radiologic Health Branch via email:

"Sequoia Consulting Inc. called the Radiologic Health Branch to report the theft of a CPN MC-3 moisture density gauge (serial number 31118). The device contains a 10 mCi cesium-137 sealed source and a 50 mCi americium-241/beryllium sealed source. A gauge operator finished a night job in Valencia, CA, and traveled to their home for a restroom break and snack. While the operator was occupied, a man driving a blue Bronco was recorded cutting the security lock securing the gauge case to the vehicle and stealing the device. The Radiologic Health Branch will continue to follow-up on this investigation.

"Local law enforcement was notified."

California 5010 Number: 052325

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

MANUAL REACTOR TRIP

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

"At 2247 CDT on 5/30/25, with Unit 2 operating in mode 1 at 39 percent reactor power, the reactor was manually tripped due to a trip of the only operating reactor recirculation pump (2B). Approximately 44 minutes prior at 2203 CDT, the 2A reactor recirculation pump tripped.

"Operations responded and stabilized the plant. Primary containment isolation systems (PCIS) received an actuation signal for groups 2, 3, 6 and 8 on reactor water level at +2 inches. All primary containment systems that received an actuation signal performed as designed. All other systems functioned as designed. Reactor water level control is via condensate and feedwater, and reactor cooldown is in progress using turbine bypass valves to the main condenser.

"Due to the reactor protection system (RPS) actuation while critical, this event is being reported as a four-hour non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B). The actuation of RPS and PCIS also requires an eight-hour non-emergency report per 10 CFR 50.72(b)(3)(iv)(A).

"There was no impact to 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 site reduced power from 100 percent following the loss of the 2A recirculation pump.