At 03:56 on 03/20/2006 an intermediate radiation alarm was received on Containment Atmosphere Particulate Radiation Monitor,
2RE-2562A. A review of other containment parameters, such as containment pressure, moisture, temperature,
sump levels and other containment radiation monitors were all stable. Chemistry was notified of the increasing particulate radiation levels in containment and immediately pulled the filter paper from radiation monitor
2RE-2562A. A gross count of the filter paper revealed the presence of Na-24 and Co-58. The presence of these two isotopes indicated the possibility of an active
RCS leak. An
RCS leakrate measurement was initiated. The results of the leakrate measurement showed no measurable change in leakrate. The total leakrate was calculated to be 0.13 gpm.
At 06:03 on 03/20/2006 a high radiation alarm was received on Containment Atmosphere Particulate Radiation Monitor, 2RE-2562A. Preparations were begun to make a containment entry to walkdown outside the bio-shield and to take a robot, equipped with a camera, to inspect inside the bio-shield.
At 13:00 personnel from the Unit 2 containment reported that a leak was visible from inside the bio-shield in the area of RCS Loop #1. Based on reports from personnel in containment, the leakage in containment was determined to be pressure boundary leakage and Tech Spec 3.4.13, "RCS Operational LEAKAGE," was entered. As required by TS 3.4.13, at 13:52 on 03/20/2006 a unit shutdown to Mode 3 was initiated to allow further investigations and repair of the leak inside containment. Abnormal Operating Procedure 18004-C, "RCS Leakage" was also entered at this time due to increasing radiation levels on, radiation monitor 2RE-2562A. Per Tech Spec 3.4.13, Mode 3 entry [is] required by no later than 19:00 on 3/20/2006 and Mode 5 entry no later than 01:00 on 3/22/2006.
The Unit shutdown is currently in progress. This is the third shutdown at the Unit for a leak in this vicinity. See similar event reports #42309 dated February 3, 2006, and #42194 dated December 9, 2005.
The licensee notified the NRC Resident Inspector.
