Event Notification Report for October 21, 2025

BOTH TRAINS OF CONTROL ROOM EMERGENCY VENTILATION SYSTEM INOPERABLE

The following is a summary of information provided by the licensee via phone and email:

On October 21, 2025, at 0610 CDT, while reloading fuel to the reactor vessel, an electrical perturbation initiated a control room ventilation isolation signal (CRVIS). The control room air conditioning system (CRACS) 'A' train A/C unit did not start upon the CRVIS due to a blown fuse. The 'B' CRACS A/C unit was out of service for planned maintenance at the time. At 1020 CDT, the 'A' train CRACS A/C unit was returned to service. Both trains of the control room emergency ventilation system (CREVS) were inoperable for 10 minutes. Due to both trains of CRACS and CREVS being inoperable, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(v).

This condition caused entry into technical specification (TS) limiting condition for operation (LCO) 3.7.10 condition `E' and 3.7.11 condition `D'. Upon discovery of the condition, fuel movement and core alterations were suspended in accordance with the TS LCO required actions.

There was no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector was notified.

TRANSPORT OF CONTAMINATED PERSON OFFSITE

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

"On 10/21/2025 at 0930 EDT an individual fell into the reactor cavity. The reactor cavity is full of water. They ingested some amount of cavity water. The individual was decontaminated by radiation protection personnel but had 300 counts per minute detected in their hair. At 1632 EDT they were sent off site to seek medical attention.

"This is an eight-hour notification, non-emergency, for the transportation of a contaminated person offsite. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xii).

"The NRC Resident Inspector has been notified."

AUTOMATIC REACTOR TRIP

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

"On October 21, 2025, at 2108 EDT, Unit 1 automatically tripped from 74 percent power due to a negative rate trip. The unit has been stabilized in mode 3 at normal operating temperature and pressure. The reactor trip was uncomplicated, and all control rods fully inserted into the core. This reactor protection system actuation is reportable per 10 CFR 50.72(b)(2)(iv)(B). The auxiliary feedwater pumps actuated as designed because of the reactor trip and is reportable per 10 CFR 50.72(b)(3)(iv)(A) for a valid engineered safety feature (ESF) actuation. Decay heat is being removed via the steam generator power-operated relief valves and Unit 1 is in a normal shutdown electrical lineup. Unit 2 was not affected by this event."

The NRC Resident Inspector has been notified.

AGREEMENT STATE REPORT - STOLEN GAUGE

The following is a summary of information provided by the California Department of Public Health, Radiologic Health Branch (the Department) via phone and email:

On October 21, 2025, the radiation safety officer (RSO) of TGR Geotechnical, Inc reported to the Department that a moisture density gauge was stolen from the transport vehicle prior to heading to a worksite in the Los Angeles area. Upon arrival at home, the operator parked the vehicle in their driveway, removed the gauge from the transport case to charge the gauge in the vehicle, and then went inside to have breakfast. Approximately 30 minutes later, the operator found the door of the vehicle open, and the gauge missing. The gauge was a Troxler model 3430 (S/N 34794, 9 mCi Cs-137, 44 mCi Am-241/Be). The RSO had confirmed the gauge trigger lock was secured. The licensee is still investigating the incident. The Department will continue to investigate the incident.

CA incident number: 5010-102125

The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:

Huntington Park Police Department was notified.

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

EN Revision Imported Date: 11/12/2025

EN Revision Text: AGREEMENT STATE REPORT - POTENTIAL OVEREXPOSURE

The following is a summary of information provided by the Arkansas Department of Health (the Department) via email:

During a routine inspection on October 21, 2025, the Department was made aware that on two separate occasions, the production manager had performed repairs on the production line of F-18 fluorodeoxyglucose (FDG) without wearing dosimetry.

On Tuesday, October 28, 2025, inspectors from the Department were following up on the concerns and confirmed that on one occasion, the production manager was not wearing dosimetry during the replacement of tubing on a cracked line inside a production hot cell. This repair was conducted along a 25.4 cm (10 inches) tubing line with one end being 10 cm (3.9 inches) from the source vial of F-18. The activity of the source was 118.4 GBq (3.2 Ci) as per the radiation safety officer (RSO). Re-enactment of the procedure was produced with the production manager to reconstruct similar parameters. The RSO initially was not made aware of the individual not wearing dosimetry. Dose estimation is currently being conducted by the RSO and by the Department. The licensee will also have an independent contractor perform a dose calculation for the event that was conducted without dosimetry.

While dose estimations are being calculated, the Department believes it has enough information to determine that this event threatens to cause an extremity exposure greater than or equal to 250 rads, and thus, are reporting immediately to the NRC in accordance with SA-300. This investigation is ongoing and updates will be provided.

Arkansas Event Number: ARK-2025-014

* * * UPDATE ON 11/10/25 AT 1357 EST FROM HUNTER BROADWAY TO KAREN COTTON * * *

The following information was provided by the Arkansas Department of Health (the Department) via email:

"A written report has been provided to the Department on November 4th, 2025, from the radiation safety officer (RSO) of the licensee regarding the investigated incidents. The Department is performing dose calculations to compare using measurements and information gathered from the investigation. The Department's time-motion study of the unbadged repair procedure by the product manager has reduced the time of exposure significantly. Due to the shortening of time, this incident is more than likely not going to exceed the reporting threshold of an extremity exposure greater than or equal to 250 rads. The Department will continue to provide updates and comparison of dose estimation.

"Important of note, there is a third incident mentioned by the RSO that occurred involving the same product manager that is referenced as the 'resin pack event'. This event occurred on October 23, between our routine inspection on October 21, 2025, and our investigation which occurred on October 28, 2025. This event was not a part of the allegation but was discussed in detail during the investigation.

"The written report was submitted from Arkansas Licensee, ARK-1008-03124 and this report will be submitted to the NMED database."

Notified R4DO (Vossmar), NMSS Events Notifications (email).