This 60-day telephone notification is being made under reporting requirements specified by
10CFR50.73(a)(2)(iv)(A) to describe an invalid actuation of a containment isolation signal affecting more than one system.
At 1920 on October 20, 2012, with the Duane Arnold Energy Center (DAEC) shut down for a preplanned refueling outage, an invalid Group 3 isolation on the 'A' side of the Primary Containment Isolation System occurred. Group 3 isolation signals were generated for Primary Containment Isolation Valves for Drywell and Torus Ventilation, and Purge, Containment Nitrogen Compressor Suction and Discharge, Recirculation Pump Seals, and Post Accident Sample System.
This event was caused by failed components in the power supply circuitry for the 'A' Refuel Floor Exhaust Radiation Monitor.
All equipment responded in accordance with the plant design. Specifically, all actuations were complete and successful.
There were no safety consequences or impacts on the health and safety of the public. The event was entered into DAEC's corrective action program for resolution.
The licensee notified the NRC Resident Inspector.
