Event Notification Report for March 18, 2025

AUTOMATIC REACTOR SCRAM

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

"At approximately 1136 CDT on March 19, 2025, with Unit 1 in mode 1 at 97 percent power, a reactor water level transient occurred which resulted in an automatic reactor scram on low reactor pressure vessel water level. The scram was uncomplicated with all systems responding as expected. The cause of the event is under investigation. Containment isolation valves actuated and closed on a valid group 2 signal.

"Operations responded and stabilized the plant in mode 3. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves.

"This event is being reported as a four-hour, non-emergency notification per 10 CFR 50.72(b)(2)(iv)(B) due to the reactor protection system actuation while critical, and an eight-hour, non-emergency notification per 10 CFR 50.72(b)(3)(iv)(A) for the Group 2 isolation signal.

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

"The NRC Resident Inspector has been notified. The state of Minnesota as well as Wright and Sherburne counties will be notified."

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

At the time of the event, condensate flushing evolutions were ongoing. It should be noted that prior to the reactor scram, a single feedwater pump tripped which would lower reactor water level.

AGREEMENT STATE REPORT - POTENTIAL DAMAGE TO A TROXLER GAUGE

The following is a summary of information provided by the Florida Bureau of Radiation Control (BRC) via email:

BRC was notified by Florida Highway Patrol (FHP) dispatch at 1036 EDT on 03/18/2025 that an FHP trooper was on the scene of a multi-vehicle accident involving a pickup truck transporting a soil moisture density gauge. BRC spoke to the FHP trooper on-scene, who reported the gauge case was intact, with no apparent damage, still secured in the back of the pickup truck.

A BRC inspector responded to the scene and confirmed the gauge and case were both intact and secure, with no apparent damage. No injuries were reported to the driver of the truck. Radiation readings of the gauge were normal, and a swipe survey revealed no leakage. The gauge was released to the owner.

The gauge is a Troxler, model 3440, serial number 25401, containing a 40 mCi Am-241/Be source, serial number 47-21689, and an 8 mCi Cs-137 source, serial number 75-8235.

FL incident report number: FL25-023.

FITNESS FOR DUTY

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

"At 1059 [CDT] on March 18, 2025, it was determined that a licensed operator failed a [random] test specified by the fitness-for-duty testing program. The individual's authorization for site access has been terminated.

"The NRC Resident Inspector has been notified."

EN Revision Imported Date: 4/7/2025

EN Revision Text: SECONDARY CONTAINMENT BOUNDARY INOPERABLE

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

"At 1026 [EDT] on March 18, 2025, it was discovered that the secondary containment boundary door was found fully open, rendering the secondary containment boundary inoperable, therefore, this condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72 (b)(3)(v). The door was closed at 1029 on March 18, 2025, and the secondary containment boundary was declared operable.

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

"The NRC Resident Inspector has been notified.

"There has been no impact to Unit 2 and Unit 3 continues to operate at 100 percent power."


* * * RETRACTION ON 04/04/25 AT 1049 EDT FROM RYAN ROBILLARD TO JOSUE RAMIREZ * * *

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

"This report retracts the 8-hour notification made on March 18, 2025, for NRC Event Number EN #57615.
"NRC Event report number 57615 describes a condition at Millstone Power Station Unit 3 (MPS3) where a secondary containment boundary door was found fully open, rendering the secondary containment boundary inoperable. This condition was reported in accordance with 10CFR 50.72(b)(3)(v)(D) as a condition that could have prevented the fulfillment of a safety function to mitigate the consequences of an accident.
"Upon further review of the conditions that existed at the time, MPS3 has concluded that the door was not blocked open. The time duration from the activation of the door security alarm to the arrival of security personnel and the subsequent closure of the door was less than four minutes. The door was left unattended for less than 40 seconds, which is less than the five-minute criteria for entry and egress without special provisions. The supplementary leak collection and release system drawdown test has sufficient margin to accommodate this unattended door time. The evaluation concluded that the secondary containment boundary remained operable throughout this event and did not lose the ability to perform its safety function to control the release of radioactive material and mitigate the consequences of an accident.

"The basis for this conclusion will be provided to the NRC Resident Inspector."

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

This event was originally reported in accordance with 10CFR 50.72(b)(3)(v)(D) and 10CFR 50.72(b)(3)(v)(C). The licensee confirmed that the retraction is applicable to both notifications.

Notified R1DO (Bickett)

FAILED FITNESS FOR DUTY TEST

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

"At 0930 EDT, March 18, 2025, it was determined that a contract supervisor failed a [random] test specified by the fitness-for-duty testing program. The individual's authorization for site access has been terminated.

"The NRC Resident Inspector has been notified."