Event Notification Report for November 12, 2025

AGREEMENT STATE REPORT - GAUGE SHUTTER FAILURE

The following information was provided by the Radiation Health Branch of the Kentucky Department for Public Health and Safety (The Department) via email:

"The Department was notified on 11/12/2025, by the radiation safety officer (RSO) from Big Rivers Electric Corporation, that during a routine six-month inventory/shutter checks, two sources were identified to have problems with the shutters closing.

"Both [gauges] measure density in the scrubber material and are mounted on piping. No exposure is possible unless the piping or gauge is removed. Primary action is to notify personnel and modify the red tag system to indicate that until this is resolved, no maintenance can be allowed on the piping because the shutters on the gauges cannot be safely closed.

"Until further notice, the piping where these gauges are mounted cannot have any maintenance activities performed on them. Red tag authorities should make note that the gauges cannot be red tagged because the shutters do not close.

"Maintenance will be performed on the gauges by an authorized contractor."

Gauge 1 information:
Manufacturer: Kay Ray
Model number: 20493
Serial number: 7062BP
Activity: 10 mCi Cs-137

Gauge 2 information:
Manufacturer: Ronan
Model number: SA8-C5
Serial number: 2104CP
Activity: 20 mCi Cs-137

AGREEMENT STATE REPORT - MEDICAL EVENT

The following information was provided by the California Department of Public Health, Radiologic Health Branch via email:

"The University of California Los Angeles (UCLA) health [center] reported that a patient being treated for liver cancer underwent a Y-90 Sirtex SirSpheres brachytherapy treatment on November 12, 2025. This is a preliminary report of a medical event, per 10 CFR 35.3045.

"The authorized user's (AU) written directive called for two vials of Y-90 activity to treat two different segments of the right lobe via two different arterial branches of the lobe. The first prescription was for 108.11 mCi and 114 mCi (105.73 percent) was successfully delivered.
"The second prescription was for the right lobe, segment 4A using 13.51 mCi but only 10.04 mCi (74.32 percent) was able to be delivered.
"The authorized user believes his patient reached stasis, so he halted the procedure per the Sirtex IFU (instructions for use). Arterial flow is intermittently checked throughout the infusion process.
"The undelivered activity was determined by measuring the exposure rate at a known distance from the post-treatment waste after the administration. UCLA health [center] will submit a 15-day report to the Department."

California 5010 Number: 111225

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.

EN Revision Imported Date: 11/21/2025

EN Revision Text: ACTUATION OF AUXILIARY FEEDWATER SYSTEM

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

"At 0748 CST, on November 12, 2025, Callaway Plant experienced an automatic actuation of the auxiliary feedwater (AFW) system in response to auxiliary feedwater actuation signals (AFAS). A low suction pressure signal was also received which aligned the AFW pumps to essential service water (ESW). An unknown amount of water from the ultimate heat sink (UHS) entered the steam generators, necessitating a plant shutdown due to exceeding secondary water chemistry program action levels. During the shutdown, with the plant at approximately 28 percent power, high vibration was received on the main turbine, requiring a manual turbine trip. The cause of the AFAS is not yet known. The plant is currently stable in mode 3.

"This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A).

"There was no impact on 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:

Decay heat is being removed via steam dump valves to the main condenser.

* * * RETRACTION ON NOVEMBER 20, 2025, AT 1409 EST FROM ZACH MILLIGAN TO JORDAN WINGATE * * *

The following is a summary of the retraction provided by the licensee via phone and email.

Event Notification 58035, made on November 12, 2025, pursuant to 10 CFR 50.72(b)(3)(iv)(A), is being retracted following a review of the cause of the auxiliary feedwater system's automatic actuation. The AFW system actuation was traced to a power supply malfunction, which also caused the auxiliary feedwater pumps to align with essential service water. Because the actuation resulted from a spurious power supply failure, rather than signals triggered by plant conditions or parameters meeting system initiation criteria, it is considered invalid and not reportable under 10 CFR 50.72(b)(3)(iv)(A).

The NRC Resident Inspector has been informed.

Notified R4DO (Drake)

HIGH PRESSURE COOLANT INJECTION INOPERABLE

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

"On November 12, 2025, at approximately 1250 EST, during surveillance testing of the high-pressure coolant injection (HPCI) system the HPCI minimum flow valve (E4150F012) would not open during stroke testing. HPCI had been removed from service for quarterly surveillance testing at 0957, November 12, 2025. The unplanned inoperability condition began at 1250 when a stroke time test was attempted, and the valve did not reposition. Since HPCI is a single-train safety system, this meets the criterion for event notification per 10CFR50.72(b)(3)(v)(D) as a condition that, at the time of discovery, could have prevented the fulfillment of a safety function needed to mitigate the consequences of an accident, based on loss of a single train safety system. Reactor core isolation cooling was and has remained operable. The Senior NRC Resident Inspector has been notified. The failure is currently under investigation."

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

Limiting conditions for operation 3.5.1 and 3.6.1.3 were entered to address HPCI inoperable. The site remains on normal offsite power, and all emergency diesel generators remain available.