Event Notification Report for June 26, 2023

AGREEMENT STATE REPORT - STOLEN MOISTURE DENSITY GAUGE

The following report was received by the California Department of Public Health (the Department) via email:

"On June 19, 2023, the licensee notified the Department that at 0100 [PDT] one nuclear gauge (Troxler 3430, SN 19706) containing 8 mCi Cs-137 and 40 mCi Am-241/Be was stolen from a locked vehicle that was parked in an apartment complex. The gauge was stored in its case that was chained and locked to the pick up truck bed. The gauge was not visible as the bed of the truck was fitted with a locking cover. The cover had been broken open and the locks securing the gauge were cut. Sacramento Police were notified and an electronic report was filed.

"The Department will investigate."

California Event Number: 061923

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

60 DAY NOTIFICATION FOR AN INVALID ACTUATION OF PRIMARY CONTAINMENT ISOLATION LOGIC

The following information was provided by the licensee email:

"This telephone notification is provided in accordance with 10 CFR 50.73(a)(1) and 10 CFR 50.73(a)(2)(iv)(A) to report an invalid actuation of Division 2 Primary Containment Isolation logic at the Monticello Nuclear Generating Plant (MNGP) that occurred while in a refueling outage.

"At approximately 0402 Central Daylight Time (CDT) on April 28, 2023 and at approximately 1611 and 2143 CDT on May 4, 2023, momentary losses of 'Y80 Division 2 Uninterruptible 120VAC Class 1E Distribution Panel', which provides power to Division 2 Primary Containment Isolation logic, resulted in a partial Primary Containment Group 2 Isolation (gas systems), initiation of the Standby Gas Treatment system, and the shift of Control Room ventilation to the high radiation mode. The momentary losses of 'Y80' were due to an intermittent, age-related degradation issue with the 'Uninterruptible Power Supply Y81, Division 2 120VAC Class 1E Inverter', which resulted in a temporary loss of output plus a lack of static switch transfer from the inverter supply to the alternate source as designed.

"The actuations were not initiated in response to actual plant conditions, these were not intentional manual initiations, and there were no parameters satisfying the requirements for initiation. Therefore, these events have been determined to be invalid actuations that were attributed to the same cause.

"All systems responded as designed to the actuation signal. Operations reset the partial Primary Containment Group 2 Isolation signal, shutdown the Standby Gas Treatment system, and restored Control Room ventilation per the procedure. There was no impact on the health and safety of the public or plant personnel.

"The NRC Resident Inspector has been notified."

AUTOMATIC REACTOR TRIP OCCURED DURING PROTECTION SYSTEM TESTING

The following information was provided by the licensee via email:

"At 1035, on June 22, 2023, with Unit 2 in Mode 1 at 100% power, the reactor automatically tripped due to `A' train reactor trip breaker and `B' train reactor trip bypass breaker opening during testing. The trip was not complex, with all systems responding normally post-trip. MST-021 (Reactor Protection Logic Train `B' At Power) testing was in progress at the time of trip.

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

"Due to the 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).

"As a result of the reactor trip, emergency feedwater actuated; therefore, this event 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."

FUEL FACILITY - SAFETY EQUIPMENT FAILED TO FUNCTION

The following information was provided by the licensee via email:

"On the first floor of the Feed Materials Building at approximately 1530 CDT on 06/21/2023 while performing cylinder filling operations, a visual indicator of material was identified and operators initiated mitigating actions in accordance with site operating procedures. It was determined that a remotely operated valve closing mechanism at the number 4 fill spot failed to close a UF6 cylinder valve. The cylinder valve was then closed manually by operations personnel. Based on preliminary observations, the licensee does not believe that regulatory limits were exceeded."

OFFSITE NOTIFICATION - ENVIRONMENTAL

The following information was provided by the licensee via email:

"At 1521 EDT on 6/23/2023, Perry Nuclear Power Plant reported elevated levels of tritium in the underdrain system to the State of Ohio as a non-voluntary reporting of tritium. An investigation is currently ongoing to identify the cause of the elevated tritium levels. The tritium levels did not exceed any NRC regulations or reporting criteria. Tritium has not been detected in any other locations and is not expected to impact groundwater or exceed any limits in the Off Site Dose Calculation Manual (ODCM).

"This notification is being made solely as a four-hour, non-emergency notification for a Notification of Other Government Agency. This event is reportable in accordance with 10 CFR 50.72(b)(2)(xi).

"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:

The following agencies were notified by licensee:
Lake County Emergency Management Agency (EMA)
Ashtabula County EMA
Geauga County Department of Emergency Services
Ohio EMA Radiological Branch