Event Notification Report for March 17, 2025

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 March 7, 2025, at approximately 1700 CST, the Department was notified by the licensee that a Troxler 3440 moisture density gauge containing an 8 mCi Cesium-137 source (original strength) and a 40 mCi (original strength) Am-241/Be source were damaged by being run over by construction equipment at a job site in Melissa, Texas. The radiation safety officer (RSO) was onsite, the sources were intact, but the gauge was damaged to an extent that the cesium source could not be retracted into a safe position. The RSO, in coordination with the Department, removed the gauge from the accident site, and made the device safe by placing it in a container filled with sand. The damaged gauge was then secured to the container, the container was secured to the licensee's vehicle, and the damaged gauge was transported to their vault which was less than 1 mile away. The manufacturer, who has a local repair facility, was already closed for the weekend so the damaged device was placed in the vault at the licensee's facility for transport to the manufacturer on Monday. The RSO performed several surveys at the accident site, with the gauge in the truck, and at the licensee's vault. All readings were well within normal limits. No overexposure occurred as the only time the source was exposed was when the RSO transferred it from the ground to the sand filled container. Additional information will be provided in accordance with SA-300."

Texas Incident Number: I-10181
Texas NMED Number: TX250018

FITNESS FOR DUTY

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

A non-licensed employee brought an illegal substance into the protected area. The employee's access to the plant has been terminated.

The NRC Resident Inspector has been notified.

EN Revision Imported Date: 3/17/2025

EN Revision Text: UNUSUAL EVENT - LOSS OF OFFSITE POWER

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

"At 1902 EDT on 3/13/2025 Turkey Point Nuclear Plant Unit 4 declared an Unusual Event due to a loss of offsite power [to the '4B' 4KV bus]. The '4B' 4KV bus was re-energized from the '4B' emergency diesel generator (EDG). The '4A' 4KV bus is de-energized as part of the pre-planned outage scope. The cause of the loss of Unit 4 startup transformer is not known at this time. All plant parameters are stable."

State and local agencies were notified. The NRC resident inspector has been notified.

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

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

The licensee is evaluating the startup transformer before transferring the '4B' 4KV bus back to offsite power. Spent fuel pool cooling remained in-service as it was powered from Unit 3. Unit 3 was unaffected and remains at 100 percent power.

* * * UPDATE ON 03/13/2025 AT 2318 EDT FROM DANIEL BITTNER TO KERBY SCALES * * *

"At 2056 EDT on 3/13/2025, Turkey Point Nuclear Station Unit 4 terminated the Unusual Event due to a loss of offsite power. The event was terminated due to more than one emergency power source being available; `4B' emergency diesel generator and `4D' bus station blackout tie."

Notified R2DO (Pearson), DHS SWO, FEMA Operations Center, CISA Central Watch Officer, FEMA NWC, DHS Nuclear SSA (email), CWMD Watch Desk (email).

* * * RETRACTION ON 03/14/2025 AT 0518 EDT FROM DANIEL BITTNER TO JORDAN WINGATE * * *

"Turkey Point Nuclear Station Unit 4 is retracting this notification based on additional information not immediately identified at the time of notification. Following the loss of the '4B' 4kV bus event on 3/13/25, the emergency action level (EAL) technical bases document for CU2.1 was reviewed and identified that more than one emergency power source was still available at the time of the event and could have been credited. Specifically, the '4B' EDG and the '4D' bus station blackout cross tie (powered by Unit 3) emergency power sources were still available. The initial report was based on the available information at the time pursuant to emergency declaration and reporting notification requirements.

"The NRC Resident has been notified."

Notified R2DO (Pearson), Region 2 RA (Miller), NRR (Bowman). IR MOC (Crouch), Region 2 PAO (Gasperson), NRR EO (Felts), and NSIR (Erlanger)

AUTOMATIC ACTUATION OF '4B' EMERGENCY DIESEL GENERATOR

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

"At 1847 EDT on 3/13/25, with Unit 4 in mode 6 and defueled, an actuation of the 4B emergency diesel generator (EDG) occurred when the Unit 4 startup transformer '4B' 4kV Bus Supply Breaker '4AB05' tripped open. The '4B' EDG automatically started and energized the '4B' 4kV Bus as designed when the undervoltage condition caused the '4B' sequencer loss of offsite power signal to be received.

"This event is being reported pursuant to 10 CFR 50.72(b)(3)(iv)(A).

"The NRC Resident Inspector has been notified."

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

All systems responded as expected for the loss of voltage. There was no impact to the health and safety of the public or plant personnel. The cause of the breaker opening is under investigation. Power remains available to the '4B' 4kV Bus via both the '4B' EDG and the station blackout tie bus.

FITNESS FOR DUTY

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

A licensed employee had a confirmed positive test for alcohol during a test specified by the FFD testing program. The employee's access to the site has been terminated.

The NRC Resident Inspector has been notified.

FITNESS FOR DUTY

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

A licensed employee violated the FFD policy. The employee's access to the plant has been terminated.

The NRC Resident Inspector has been notified.

AUTOMATIC START OF THE DIVISION III EMERGENCY DIESEL GENERATOR

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

"On March 15, 2025, at 1248 CDT, Grand Gulf Nuclear Station (GGNS) was operating in mode 1 at 100 percent reactor power when a grid disturbance (degraded voltage) resulted in a valid specified system actuation (automatic start) of the division Ill emergency diesel generator (EDG). The division Ill EDG started and repowered the '17' AC safety-related electrical bus as designed.

"GGNS is currently in mode 1 at 100 percent reactor power. No radiological releases have occurred due to this event and no other safety system actuations occurred.

"This event is being reported under 10 CFR 50.72(b)(3)(iv)(A), as an event or condition that results in a valid specified system actuation due to the automatic start of the division Ill EDG on bus undervoltage due to a grid disturbance.

"The NRC Senior Resident Inspector has been notified."