Event Notification Report for May 04, 2026

AGREEMENT STATE REPORT - STUCK RADIOGRAPHY SOURCE

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

"On April 23, 2026, the licensee reported that one of their radiography crews was unable to retract a source back into a QSA 880D exposure device. The device contains an 88.4 curie iridium-192 source. The radiation safety officer (RSO) reported the crew was conducting an exposure when a pipe rolled onto the guide tube crimping it to a point where they were unable to retract the source beyond the crimp. The radiographers drove the source back into the collimator. The radiographers isolated the area and contacted the site RSO. The RSO responded to the location and placed bags of lead shot over the source/collimator. The RSO tapped on the crimp in the guide tube until the guide tube was open enough for the source to be retracted into the fully shielded position in the exposure device. No overexposures occurred due to this event.

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

Texas incident number: 10285

STUCK SHUTTER

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

The license reported that the normally open shutter on a fixed gauge could not be closed during semiannual testing. The gauge is a Vega model SHF1 with a 10 mCi Cs-137 source. Access to the refiner vessel where the gauge is installed has been restricted by protective tagging to prevent inadvertent exposures.

The licensee has contacted the manufacturer for repair or replacement of the gauge.

AGREEMENT STATE REPORT - STOLEN GAUGE

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

"On April 27, 2026, at approximately 0631 PDT, the radiation safety officer (RSO) from the licensee contacted RHB to report the theft of a moisture/density gauge, a CPN model MC-3 (S/N M31106358) with 0.370 GBq Cs-137 and 1.85 GBq Am-241/Be sources. The gauge had been in the back of an open bed pick-up parked in front of a room at a local hotel. The cables and locks were cut, and the gauge was removed from the truck bed. The authorized user, who left the radioactive gauge unmonitored while collecting the rest of his belongings from the room, discovered the missing radioactive gauge at approximately 0530 PDT on April 23, 2026. The authorized user notified the RSO and then notified the Monrovia Police Department to complete a theft report. A copy of the theft report will be forwarded to the RHB office. The RSO will contact local newspapers in Monrovia in an attempt to retrieve the stolen radioactive gauge, as well as notifying local servicing vendors of radioactive gauges to be alert for the serial number of the stolen gauge in case it turns up for service. The investigation will continue to determine if the radioactive gauge can be recovered."

California 5010 number: 042726

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

VALID EMERGENCY DIESEL GENERATOR ACTUATION

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

"On May 1, 2026, at 1508 CDT, with both units at full power, the South Texas Project (STP) switchyard north bus was de-energized (locked out). This loss of power de-energized the standby '1' transformer, which was aligned to supply power to the `1B' 4KV engineered safety feature (ESF) bus. This resulted in a specified system actuation of emergency diesel generator (EDG) `1B' on the undervoltage condition, to automatically start the '1B' EDG, power the '1B' 4KV ESF bus, and sequence on select loads.

"The cause of the [switchyard north bus] lockout is under investigation at this time.

"This event is reportable under 10 CFR 50.72(b)(3)(iv)(A) as an event that resulted in the valid actuation of an emergency AC electric power system per 10 CFR 50.72(b)(3)(iv)(B)(8). There was no failure of automatic equipment to start.

"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:

Offsite power had been restored to the `1B' 4KV ESF bus and the '1B' EDG returned to standby by the time of notification.