Event Notification Report for December 11, 2024

AGREEMENT STATE REPORT - LOST EXIT SIGNS

The following is a summary of information provided by the Colorado Department of Public Health and Environment via email:

Eight tritium exit signs were determined to be lost by the licensee.

Manufacturer: Safety Light Corp.
Number of signs: 2
Model: 2040
Activity = 11.5 Ci each, H-3

Manufacturer: Best Lighting Products
Number of signs: 6
Model: SLXTU1GB10
Activity: 7.03 Ci each, H-3

Notifications: Colorado Regulations Section 4.51.1.1 (10 CFR 20.2201(a)(1)(i))

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

SECONDARY CONTAINMENT INOPERABLE

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

"At 0930 CST on 12/10/2024, Arkansas Nuclear One, Unit 1, discovered both isolation valves open in a one-inch breathing air line containment (reactor building) penetration. This resulted in inoperable reactor building isolation valves in a required mode of applicability per Unit 1 Technical Specification 3.6.3 and an inoperable reactor building per Unit 1 Technical Specification 3.6.1. Unit 1 had recently entered the modes of applicability for both Technical Specifications at 0556 CST on 12/8/2024 following a planned maintenance outage.

"The outside isolation valve was locked closed at 0950 CST on 12/10/2024, restoring operability of the reactor building. The inside valve was locked closed at 1345 CST on 12/10/2024, restoring operability of both isolation valves.

"This condition is being reported under 10 CFR 50.72(b)(3)(ii)(B) as an event or condition that resulted in the nuclear power plant being in an unanalyzed condition that significantly degrades plant safety. This condition is also being reported under 10 CFR 50.72(b)(3)(v)(C) and (D) as an event or condition that, at the time of discovery, could have prevented the fulfillment of the safety function of structures or systems that are needed to: (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident.

"There was no impact to 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 cause of the out-of-position valves is under investigation. No evolutions were in progress besides a plant startup at the time of the event.