This telephone notification is being provided in accordance with
10CFR50.73(a)(1) for an invalid actuation reportable under 50.73 (a)(2) (iv)(A).
On March 15, 2010 at 0138 hours0.0016 days <br />0.0383 hours <br />2.281746e-4 weeks <br />5.2509e-5 months <br />, during full power operations, Division 2 Drywell Ventilation (VP) and Drywell Cooling (WO) Primary Containment Isolation Valves (PCIVs) closed for isolation Groups 11 and 17. The affected valves were inboard PCIVs 1VP005A, 1VP005B, 1VP014A, 1VP014B, 1WO001B, 1W0002B, 1WO551B and1WO552B. The shunt trip devices for the breakers for the following components were tripped: Drywell cooling fan 1B (1VP01CB), Drywell cooling fan 1D (1VP01CD), Drywell chiller 18 oil pump, DC Motor Control Center (MCC) 1B ground detection, DC MCC 1B ground detection, Drywell Chiller 1B(1VP04CB), and Drywell Chiller control panel 1B.
The cause of the isolation was determined to be that a Division 2 load driver card spuriously actuated all of its loads without a valid Loss Of Coolant Accident (LOCA) signal or a manual initiation signal present. A reset of the Group 11 and 17 isolations was completed at 0208; the shunt trips were reset at 0215; and Drywell Cooling was restored by 0259 on March 15. The load driver circuit remained in service until a replacement load driver card could be installed on March 19, 2010. The cause of the card failure could not be determined; however the most probable cause is either an intermittent failure of the card or an intermittent short of the output connectors.
The actuation of primary containment isolation Groups 11 and 17 was complete and the isolation/actuation was limited to only these two groups.
The NRC Resident Inspector was notified of this notification.
