On 9/25/2008 at approximately 0241 [EDT], the James A. Fitzpatrick Nuclear Power Plant was Shutdown in the refueling mode. The 'A' Reactor Protective System (
RPS) Motor-Generator (
MG) Set tripped. This resulted in a half-scram signal and Group II
Primary Containment Isolation System [PCIS] actuation. The Group II
PCIS isolation actuated valves in multiple systems.
During the event all systems operated as designed.
Power was restored to 'A' RPS using the alternate power supply and the Group II PCIS isolation was reset.
The cause of the event was determined to be a loose connection on the 'A' RPS MG Set voltage regulator. The Voltage regulator was replaced and the RPS System was returned to its normal line-up.
The event is reportable under 10 CFR 50.73(a)(2)(iv)(A) 'Any event or condition that resulted in manual or automatic actuation of ... (B)(2) general containment isolation signals affecting containment isolation valves in more than one system'. A telephone notification is being made in lieu of an LER, pursuant to 10 CFR 50.73 (a)(1) as an invalid signal.
The licensee notified the NRC Resident Inspector.
