Event Notification Report for June 11, 2026

EN Revision Imported Date: 6/11/2026

EN Revision Text: SOURCE LOST DURING SHIPMENT

The following information was provided by the licensee via phone:

A 0.182 TBq Ir-192 sealed source was lost in shipment by a common carrier. The package, a UN3332 Type A container with overpack, was picked up by the common carrier on April 25, 2025. The carrier's origin and interim sorting facilities have been searched and failed to locate the package. A search is on-going at the carrier's central sorting facility in Memphis, Tennessee. The source was in the process of being shipped to the source supplier in Vinton, LA for disposition.

* * * UPDATE ON 06/10/2026 AT 1126 EDT FROM VARIAN MEDICAL SYSTEMS TO JORDAN WINGATE * * *

The shipment was delivered by the common carrier to the intended recipient in August 2025, but no update was provided to the licensee. The shipment is no longer considered lost.

Notified R1DO (Elkhiamy), R4DO (Dodson), NMSS Events Notification (email), and ILTAB (email).

THIS MATERIAL EVENT CONTAINS A 'Category 3' LEVEL OF RADIOACTIVE MATERIAL

Category 3 sources, if not safely managed or securely protected, could cause permanent injury to a person who handled them, or were otherwise in contact with them, for some hours. It could possibly - although it is unlikely - be fatal to be close to this amount of unshielded radioactive material for a period of days to weeks. These sources are typically used in practices such as fixed industrial gauges involving high activity sources (for example: level gauges, dredger gauges, conveyor gauges and spinning pipe gauges) and well logging. For additional information go to http://www-pub.iaea.org/MTCD/publications/PDF/Pub1227_web.pdf

AGREEMENT STATE REPORT - DAMAGED MOISTURE DENSITY GAUGE

The following information was provided by the Texas Department of State Health Services (the Department) via phone and email:

"On June 3, 2026, the Department was notified by the license's radiation safety officer (RSO) that a InstroTek model 3500 gauge, containing a 40 millicurie americium-241 source and an 8 millicurie cesium-137 source, had been damaged at a temporary work site.

"The event occurred when the technician walked about 15 feet from the device, and while their back was to the gauge, a truck backed over the gauge and bent the cesium source operating rod. The source was in the fully shielded position when the gauge was struck. The lock was on the gauge at the time of the event but broke off when the gauge was hit. The source remained in the fully shielded position. The RSO stated they did not try to operate the cesium source rod for fear it would get stuck outside the shielded position. The RSO stated that the bent operating rod appeared to be the only damage the gauge suffered.

"The RSO stated that a radiation survey conducted of the gauge after the event showed the radiation levels were normal. The RSO stated no individual received any significant exposure during this event.

"The RSO stated the gauge was being taken to a service provider to be repaired.

"Additional information will be provided as it is received in accordance with SA-300."

Texas incident number: 10299
NMED number: TX260019

AGREEMENT STATE REPORT - STOLEN TRITIUM EXIT SIGNS

The following information was provided by the California Department of Public Health, Radiologic Health Branch (CDPH/RHB) via email:

"On June 3, 2026, the licensee reported the theft of three tritium exit signs from their AMC Theatre Riverside facility.

"The exit signs were Isolite brand tritium exit signs, model 2040-95, purchased in 2017, with current tritium activity estimated to be between approximately 5 Ci to 15 Ci of tritium per sign, depending on their original activities. Their original activities are not currently precisely known. The exit signs were reported stolen to the Riverside police department on March 18, 2026. [The licensee] stated in the police report that during a monthly exterior building check in January 2026, staff noticed that three exit signs were missing, but they were not sure when exactly they were stolen. These exit signs were located inside plastic housings and receded into walls of the parking structure area of the galleria complex below the theatre.

"These exit signs have not been recovered.

"When making a replacement exit sign purchase order from their vendor, the project manager informed [the licensee] that the theft needed to be reported to the CDPH/RHB.

"CDPH/RHB is continuing to investigate this event."

California 5010 number: 060326

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

FITNESS FOR DUTY

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

"At 0934 CDT on June 9, 2026, it was determined that a non-licensed supervisor failed a test specified by the fitness-for-duty testing program. The individual's authorization for site access has been terminated.

"The NRC Resident Inspector has been notified."

AGREEMENT STATE REPORT - STUCK OPEN GAUGE SHUTTER

The following is a summary of information provided by the Washington State Office of Radiation Protection via email:

The licensee reported that the shutter device on a Vega Ohmart model SH-F1 fixed level gauge with a 100 mCi Cs-137 source failed. The facility maintenance department was attempting to isolate the device as part of a normal procedure but was unable to close the shutter. The licensee stated that with the shutter stuck in an open position, the device is still functioning in a normal capacity. The licensee stated the gauge is installed on a digester vessel and is not currently presenting an abnormal risk of employee exposure.

The licensee has contacted the manufacturer, who is currently providing guidance for another attempt to isolate the device. The licensee expects the manufacturer will need to provide onsite support to repair or remove the device from service. The manufacturer has communicated that replacement parts for Ohmart SH-F1 model source holders are no longer supported, so the licensee anticipates replacing the gauge with a new unit.

The licensee reported that radiation levels in the area of the gauge were recorded at 0.6 mrem/hr. The work area has been cleared and yellow tape boundaries established.

Washington report number: WA-26-008

INVALID SPECIFIED SYSTEM ACTUATION

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

"This report is being made in accordance with 10 CFR 50.73(a)(2)(iv)(A) using the telephone option in 50.73(a)(1) in lieu of a written LER [licensee event report] concerning an event in which Callaway experienced an automatic start of the turbine driven auxiliary feedwater pump (TDAFP) in response to an invalid auxiliary feedwater actuation signal. The reactor protection system was not involved.

"This TDAFP actuation was complete, and the TDAFP started and functioned successfully in accordance with the initiating actuation signal.

"This actuation occurred at 2149 CDT on May 17, 2026.

"The most probable cause of the actuation was a voltage perturbation caused by switching inverters in preparation for tagging out the in-service inverter, resulting in the TDAFP receiving a start signal. This signal did not result from plant conditions or parameters satisfying the requirements for initiation of the system. Therefore, the actuation was invalid."

The NRC Resident Inspector was notified.

PART 21 - RELAY FAILURE

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

"On June 9, 2026, STP [South Texas Project] Nuclear Operating Company (STPNOC) completed a Part 21 evaluation which identified a defect with TE Connectivity MDR styled relays (MDR 131-1 and MDR 134-1) manufactured after mid-year 2020. Since 2023, eleven (11) of these relays in both Unit 1 and Unit 2 have experienced premature failures resulting in essential chillers being inoperable and incapable of fulfilling their intended safety function. The relays were procured as commercial grade items and were dedicated by STPNOC solely for use at STP. An investigation determined that the relay failures resulted from overheating of the relay coils during operation. The vendor informed STP that a subcontractor responsible for rotor grinding produced relay rotors that were undersized and outside of specification. The reduced rotor dimensions resulted in a looser fit between the rotor and stator, reducing eddy currents and increasing coil current consumption. The increased coil wattage then generated excessive heat that caused the relay windings to short at the finish lead, resulting in relay failure. A written notification in accordance with 10 CFR 21.21 (d)(3)(ii) will be provided within 30 days.

"The NRC Resident Inspector has been notified, June 10, 2026, at 1330 CDT."

FITNESS FOR DUTY

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

"At 1226 MST on June 10, 2026, it was determined that a non-licensed contractor supervisor failed a test specified by the fitness-for-duty testing program. The individual's authorization for site access has been terminated.

"The NRC Resident Inspector has been notified."