Event Notification Report for May 22, 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

DEGRADED RHR CHECK VALVE

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

"On May 22, 2025, at 2358 CDT, River Bend Station determined that a degraded condition existed following the performance of a VT-3 examination of E12-AOVF041A, Residual Heat Removal (RHR) 'A' injection line testable check valve. The cause of this event is currently being investigated. This examination was conducted following the plant shutdown, which was reported in Event Notification (EN) 57725.

"This event is being reported as an 8-hour reportable condition in accordance with 10 CFR 50.72(b)(3)(ii)(A) for the degraded condition of the pressure boundary.

"The NRC Resident Inspector has been notified."

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

This degraded condition resulted in a leakage rate of approximately 3.6 gallons per minute when at pressure. The plant is shutdown and depressurized which has caused the leakage to stop. No release is occurring or expected and possible corrective actions are being evaluated.

NOTICE OF UNUSUAL EVENT- FIRE IN BATTERY BANK

The following information was provided by the licensee via phone:

At 0359 CDT, Quad Cities Unit 2 experienced a fire in one of their battery cells during a planned discharge test. An Unusual Event (HU.3) was declared at 0413 CDT and the fire was extinguished by the fire brigade at 0422 CDT.

The effected battery bank was isolated at the time of the event and all other electrical systems are functioning normally. Unit 2 remains in Mode 1 at 100 percent power and Unit 1 was unaffected. No injuries have been reported.

The NRC Senior Resident Inspector, state, and local authorities have been notified.

The event was terminated at 0520 CDT due to the fire being out and no other plant equipment being affected.

Notified DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC (email), DHS Nuclear SSA (email), CWMD Watch Desk (email).

EN Revision Imported Date: 5/27/2025

EN Revision Text: TECHNICAL SPECIFICATION VIOLATION

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

"On May 22, 2025, at 1055 EDT, the Armed Forces Radiobiology Research Institue (AFRRI) TRIGA Mark F reactor experienced a high power scram during startup in steady-state mode under two rod automatic control. During power escalation, the log channel malfunctioned, failing to provide a period signal to the automatic control system. The reactor power level increased rapidly until high flux safety channels 1 and 2 caused an automatic scram, releasing control rods to shutdown the reactor. Due to rate of power increase, reactor power momentarily exceeded the steady-state limit of 1.1MW. All reactor protection systems functioned as designed. Reactor power was verified as decreasing; control rods were verified to be fully inserted. The safety limit, nor limiting safety system setting, were exceeded during the event.

"This event is reportable to the NRC under AFRRI Technical Specifications (T.S.) 6.5.2.b. and 6.5.2.c.

"The limiting condition of operations affected are T.S. 3.1.1. - Steady state power level exceeding 1.1MW, T.S. 3.2.1.a. - Log Channel inoperable, and T.S. 3.2.2. Table 3 - Failure of Rod Withdrawal Interlock for a period less than three (3) seconds.

"The NRC Project Manager will be notified."

PART 21 REPORT - DIESEL GENERATOR JACKET WATER PUMP FAILURE

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

"On April 8, 2025, while in Mode 1 and at 100 percent power, during performance of a scheduled monthly surveillance test, Nebraska Public Power District (NPPD) Cooper Nuclear Station (CNS) identified Diesel Generator (DG) 1 jacket water (DGJW) pump may not be providing sufficient cooling water to the DG. The DGJW pump impeller was found to have slipped on the shaft as a result of a failure to achieve the required interference fit during preventive maintenance replacing the pump seal. On May 22, 2025, subsequent investigation identified a deviation in that the originally supplied Cooper-Bessemer DGJW impeller bore was not provided in accordance with the design drawing. Due to the bore dimensional deviation, the required interference fit was not achieved, resulting in shaft rotational and torsional forces challenging the compromised fit until the impeller was able to spin freely on the shaft.

"On June 19, 2025, NPPD completed an evaluation and determined that the deviation represents a defect that could create a substantial safety hazard as defined in 10 CFR 21, as this pump was approved for use in a safety application. NPPD is not aware of any other plants being impacted by this issue.

"The NRC Resident Inspector has been notified. A written notification will be provided within 30 days."

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

Maintenance performed on the DGJW pump was completed on April 9, 2025.