At 0817, 4 of the 5 ball valves associated with the Traversing Incore Probe (
TIP) system were discovered to be open. In conjunction with explosive shear valves located on each line, these ball valves function to isolate the
primary containment upon the receipt of a containment isolation signal. Further investigation revealed that the associated
TIP detectors were in the drywell at the indexer. With the
TIP detectors in the drywell the detector cable is passing through the ball valves and this condition renders the valves
inoperable. This condition had existed for approximately 48hrs and was due to improper shutdown of the system on May 5, 2009.
This is a violation of technical specification 3.6.3 and resulted in a condition which would have prevented the automatic safety function of the TIP system to control the release of radioactive material during an accident. The explosive shear valves are manually actuated per Operations abnormal procedures should a ball valve not close during accident conditions and remained operable throughout the time the ball valves were impaired.
At 0937 the TIP detectors were withdrawn to their chamber shields, the ball valves closed and declared operable.
This event was limited to the TIP system and its associated containment penetrations. Plant operation was not affected. Investigation is in progress and will be entered into the station's corrective action program. There was nothing unusual or not understood. All safety related equipment and systems are operable.
The licensee notified the NRC Resident Inspector.
Notified the R1DO(Caruso).
