Event Notification Report for July 31, 2025

AGREEMENT STATE REPORT - RECOVERED SOURCES

The following report was received by the Georgia Radioactive Materials Program via email:

"On March 27, 2025, two sources (Ge-68) were found at a car repossession lot. It was determined the sources had been at that car repossession lot since sometime in October of 2024 and remained there until March 27, 2025, at which time GFD Hazmat recovered them and handed them off to EPD. The original activity was 1.49 mCi per source. The estimated decayed value was 0.05 mCi at the time of discovery and 0.04 mCi to date. The manufacturer confirmed the shipping location (GA 1490-1) and date of the source with a serial number.

"The licensee responded with disposal records to Sanders Medical (Tennessee licensed facility). Sanders was able to confirm receipt of the material on April 15, 2025. It was determined the serial numbers listed on the lead pigs did not match the serial number of the enclosed sources.

"On April 15, 2025, GA 2047-1 (Training Facility) gained possession of the found sources. The manufacturer (EZ) confirmed the same shipment location and licensee with the accurate serial numbers. After several attempts to reach out to Sanders, for confirmation of receipt, the State of Georgia could not get a response until July 15, 2025. At that time, a staff member from Sanders confirmed they did not receive, nor have they ever received the two sources.

"The licensee was unable to provide disposal records for the sources, although routinely uses Sanders for disposal services. The licensee received a notice of violation on July 23, 2025."

Georgia Incident Number: 102

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

AGREEMENT STATE REPORT - MEDICAL EVENT

The following information was provided by the Illinois Emergency Management Agency (the Agency) via phone and email:

"The Agency was contacted on July 23, 2025, by Rush University Medical Center in Chicago to advise of an administration of Y-90 Theraspheres which resulted in an underdose exceeding 20 percent. The incident occurred on July 22, 2025. No untoward medical impact to the patient is expected.

"The Agency was contacted by the radiation safety officer for Rush University Medical Center (radioactive materials license: IL-01766-01), on July 23, 2025, to report that a patient prescribed 47.42 mCi of Y-90 Theraspheres on July 22, 2025, received only 36.81 mCi of the prescribed dose.

"The patient has been notified, and inspectors will verify that the referring physician was notified during a reactive inspection scheduled to occur on July 29, 2025. There was no reported adverse impact to the patient. The licensee reported using a smaller than recommended catheter due to the area being treated. The underdose (22.4 percent deviation between the prescribed and administered dose) meets the criteria as a reportable event under 32 Illinois Administrative Code 335.1080. The prescribed and administered dose (in terms of Gy) will be confirmed on site. The investigation remains ongoing. This medical event will be reported to the NRC Operations Center today, July 24, 2025."

Illinois item number: IL250029

A Medical Event may indicate potential problems in a medical facility's use of radioactive materials. It does not necessarily result in harm to the patient.

AGREEMENT STATE REPORT - POTENTIAL OVER EXPOSURE

The following report was received by the Georgia Radioactive Materials Program via email:

"The licensee's radiation safety officer called and stated that, during a high dose rate procedure, the nurse got stuck in the vault and was behind the CT [computed tomography] lead shielding. The licensee plans to send out her dosimetry badge to be processed for dose received and perform a pregnancy test.

"[The Georgia Radioactive Materials Program] will follow up with more information as we receive it."

Additional information: The equipment involved was a GammaMedPlus 3/24iX remote brachytherapy afterloader containing a Ir-192 source with an activity of 3.158 curies.

Georgia Incident Number: 104

EN Revision Imported Date: 7/31/2025

EN Revision Text: BOTH TRAINS OF CONTROL ROOM AIR CONDITIONING INOPERABLE

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

At 2324 CDT, on July 28, 2025, control room air conditioning (CRAC) 'B' tripped at Grand Gulf Nuclear Station (GGNS) approximately 5 minutes after loading the compressor by adjusting the thermostat [down] per standby service water quarterly surveillance instructions. CRAC 'A' was manually started at 2326 CDT and at 2329 CDT it subsequently tripped. After investigating the compressors and breakers per the alarm response instructions with no abnormal indications, CRAC 'B' was restarted and tripped again. Cooling water was rotated from plant service water to standby service water and CRAC 'A' was successfully restarted at 2358 CDT and remains in service.

While both control room air conditioning subsystems were inoperable GGNS entered technical specification limiting condition of operation (LCO) 3.7.4 condition 'B', actions requiring verification of control room temperatures less than 90 degrees F and restoring one subsystem to operable status in 7 days. Control room temperatures reached 79 degrees F, maximum, before CRAC 'A' was restarted. GGNS has exited condition 'B' in LCO 3.7.4 and entered condition 'A' to restore CRAC 'B' in 30 days.

This event is being reported in accordance with 10 CFR 50.72(b)(3)(v)(D) as an event or condition which could have prevented the fulfillment of a safety function.

The NRC Senior Resident Inspector has been notified.

* * * RETRACTION FROM JEFFERY HARDY TO SAMUEL COLVARD AT 1648 EDT ON 07/30/2025 * * *

"Investigation of the cause of the control room air conditioning (CRAC) `A' and `B' trips identified a plant service water / standby service water (SSW) crosstie valve which failed in its safety-related (closed) position as the cause. In an accident or transient, cooling water to CRAC `A' compressors would have been successfully provided by the safety-related SSW. As a result, CRAC `A' remained capable of fulfilling its safety function to maintain the control room environment less than 90 degrees F.

"The NRC Senior Resident Inspector has been notified of this retraction."

Notified R4DO (Drake).

MANUAL REACTOR SCRAM

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

At 2058 CDT on 7/28/2025, a spurious trip of the reactor building exhaust ventilation [system] caused a subsequent trip of the reactor building supply ventilation [system]. This ventilation system failure resulted in the degradation of reactor building differential pressure and at 2200 CDT the differential pressure exceeded the technical specification limit, resulting in the inoperability of Secondary Containment. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72 (b)(3)(v).

Failure of the ventilation system also resulted in elevated temperatures in the steam chase area of the plant. Operators reduced power to slow the temperature rise, however, at 2324 CDT on 7/28/2025 with Unit 1 in mode 1 at 41 percent power, the reactor was manually scrammed due to steam chase temperatures reaching the procedural limit. The scram was not complex, with all systems responding normally post-scram. Reactor water level is being maintained via the feedwater system. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. This condition is being reported as a four-hour, non-emergency notification per 10 CFR 50.72 (b)(2)(iv)(B). There has been 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:

Steam chase temperature has begun to lower, and the licensee intends to cooldown to mode 4 for maintenance.

FITNESS FOR DUTY EVENT

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

"On July 28, 2025, Watts Bar Nuclear (WBN) operations was informed that a WBN licensed reactor operator had tested positive for a controlled substance, in violation of the Tennessee Valley Authority (TVA) fitness for duty policy. A random screening was completed on July 17, 2025. The results were sent to the TVA medical review officer on July 28, 2025. The test was declared positive for a controlled substance and WBN operations was notified at 1333 EDT on July 28, 2025. The individual's unescorted access has been revoked."

The NRC Resident Inspector has been notified.

PART 21 - THERMAL OVERLOAD OF VOLTAGE REGULATORS

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

"This is an initial report notification pursuant to 10 CFR Part 21.21.

"Cook Nuclear Plant completed an internal evaluation concerning an issue with an emergency diesel generator (EDG) voltage regulator (VR) supplied by Paragon Energy Solutions, LLC. An issue was identified during a surveillance test conducted on April 22, 2025, concerning a thermal overload (TOL) for the VR which spuriously trips causing a condition where the EDG VR can no longer control the generator voltage, resulting in the inability of the EDG to supply automatic onsite emergency AC power. A failure analysis was completed on June 6, 2025, determined that the cause of the spurious trips is associated with a heater dimensional tolerance deficiency lowering the activation threshold of the TOL bimetallic strip and a workmanship deficiency associated with a braided control wire restricting the movement of the TOL pressure bar. Extent of condition examinations were performed and one additional TOL was found to be impacted. The two impacted TOLs have been replaced. A written notification will be provided within 30 days."

Affected Plants: Cook Nuclear Power Plant.

The NRC Resident has been notified.

AUTOMATIC REACTOR TRIP

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

"On July 30, 2025, at 1230 CDT, with Unit 1 in mode 1 at 100 percent power, the reactor automatically tripped due to an over temperature delta 'T' reactor protection system actuation while critical. This event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B).

"Actuation of the auxiliary feedwater [system] occurred during the reactor trip response. The cause of the auxiliary feedwater auto-start was a LO-2 steam generator water level. The 1A and 1B auxiliary feedwater pumps started as designed when the LO-2 steam generator water level signal was received. This event is being reported in accordance with 10 CFR 50.72(b)(3)(iv)(A) as an event that results in a valid actuation of the auxiliary feedwater system. Operators responded using procedures 1BwEP-0 and 1BwEP ES-0.1 to stabilize the unit in mode 3.

"Decay heat is being removed by discharging steam to the main condenser using the main steam dump valves. Unit 2 is not affected. All systems responded as expected with the exception of steam pressure channel 1Pl-545A and steam flow channel 1Fl-523A, which both failed high during the lightning storm and subsequent transient. Actions per 1BwOA lnstrument-2 are in progress to address these failures.

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

"The NRC Resident Inspector has been notified."

INVALID ACTUATION OF PRIMARY CONTAINMENT ISOLATION SYSTEM (PCIS) GROUP 6

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

"This 60-day telephone notification is being made per the reporting requirements specified by 10 CFR 50.73(a)(2)(iv)(A) and 10 CFR 50.73(a)(1) to describe an invalid actuation of a general containment isolation signal affecting more than one system.

"On May 30, 2025, during de-inerting of the Unit 2 drywell for a forced outage, Unit 2 received a partial primary containment isolation system (PCIS) group 6 isolation. Additionally, standby gas treatment system (SGT) trains `B' and `C' auto started.

"Plant conditions which initiate PCIS group 6 and SGT actuations are reactor vessel low water level (Level 3), high drywell pressure, or reactor building ventilation exhaust high radiation (reactor zone or refuel zone). At the time of the event, these conditions did not exist; therefore, the actuation of the PCIS and SGT was invalid.

"Upon investigation, a fuse was found to have failed as a result of a hot spot due to a corroded lug, which was the cause of the isolation. The fuse was replaced, [lug cleaned], condition was cleared, and all systems were realigned as necessary.

"There were no safety consequences or impact to the health and safety of the public as a result of this event.

"This event was entered into the Corrective Action Program as Condition Report 2017035.

"The NRC Resident Inspector has been notified of this event."