05000395/LER-2006-002
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| 3952006002R00 - NRC Website | |
PLANT IDENTIFICATION
Westinghouse — Pressurized Water Reactor
EQUIPMENT IDENTIFICATION
Radiation Monitoring
IDENTIFICATION OF EVENT
On 10/06/06, the Reactor Building Alternate Purge system was in service to provide cleanup for the reactor building atmosphere in preparation for the refueling outage (RF-16). Technical Specification (TS) 3.3.2, Table 3.3-3, Item 3.c.2 requires two radiation monitors to be available to automatically and independently isolate reactor building purging operations in the event of high containment activity. While purging was in progress, operators commenced steps in Surveillance Test Procedure (STP) 0144.001 to stroke-test the containment isolation valves for Radiation Monitor RMA 2. On 10/06/06 at 2030, the sample pump was secured per the STP, which made RMA 2 inoperable. At this point, the station had only one of the two required radiation monitors available during purging operations and thus was no longer in compliance with TS 3.3.2. Upon receiving the trouble alarm on RMA 2, personnel in the control room recognized that RMA 2 was inoperable coincident with the ongoing purging operations.
Subsequently, the sample pump for RMA 2 was restarted which brought the station back into compliance with TS 3.3.2. The station was in violation of TS 3.3.2 for approximately one minute. During this time, Radiation Monitor RMA 4 was operable and available to isolate reactor building purging operations in the event of high containment activity.
EVENT DATE
10/06/06
REPORT DATE
11/11/06
CONDITIONS PRIOR TO EVENT
Mode 1, 80% Power
DESCRIPTION OF EVENT
On 10/06/06, the Reactor Building Alternate Purge system was in service to provide cleanup for the Reactor Building atmosphere in preparation for the refueling outage (RF-16). Technical Specification (TS) 3.3.2, Table 3.3-3, Step 3.c.2 requires two radiation monitors to be available to automatically and independently isolate reactor building purging operations in the event of high containment activity. The on-duty operations shift had just returned to work their first of four nights after being away from shift.
When they were previously on shift, the station was at 100 % power with no reactor building purging in progress. When they returned to shift, the plant was at 80% power with purging in progress. While purging was in progress, operators commenced steps in Surveillance Test Procedure (STP) 0144.001 to stroke-test the containment isolation valves for Radiation Monitor RMA 2.
There is no precaution in STP0144.001 concerning performance of this test during reactor building purging operations. Also, the STP was reviewed by the Control Room Supervisor (CRS) and by an Control Room Supervisor Under Instruction (CRSUI) for impact and determined that there was no impact. On 10/06/06 at 2030, the sample pump was secured per the STP, which made RMA 2 inoperable. At this point, the station had only one of the two required radiation monitors available during purging operations and thus was no longer in compliance with TS 3.3.2. Upon receiving the trouble alarm on RMA 2, personnel in the control room recognized that RMA 2 was inoperable coincident with the ongoing purging operations. Subsequently, the sample DESCRIPTION OF EVENT continued....
pump for RMA 2 was restarted, which brought the station back into compliance with TS 3.3.2. The station was in violation of TS 3.3.2 for approximately one minute. During this time, RMA 4 was operable and available to isolate reactor building purging operations in the event of high containment activity to prevent a radioactive release to the environment.
CAUSE OF EVENT
Inadequate procedural guidance is the primary factor contibuting to securing RMA 2 during reactor building purging operations.
There was no caution in STP0144.001 concerning the requirement for the operability of RMA 2 during purging operations.
Another contributing factor is the incomplete evaluation of plant conditions by the operating shift prior to commencing this STP.
ANALYSIS OF THE EVENT
RMA 2 was inoperable for approximately one minute during reactor building purging operations. During this time, RMA 4 was operable and available to isolate reactor building purging operations in the event of high containment activity to prevent a radioactive release to the environment.
CORRECTIVE ACTIONS
Condition Evaluation Report (CER) 06-3273 was generated to document the event and perform an apparent cause evaluation to determine the appropriate corrective actions. The immediate corrective action of restoring the operability of RMA 2 was performed in approximately one minute. The operating shift then verified the validity of the release permit for purging operations. Main Control Board (MCB) indicating tags were subsequently hung to indicate that reactor building purge was in progress. An enhancement to STP0144.001 is being considered that would insert a caution concerning radiation monitoring requirements during purging operations. Another enhancement being considered would proceduralize the hanging of the MCB indicating tags on RMA 2 and RMA 4, and their respective channel modules, whenever purging operations are in progress.
PRIOR OCCURENCES
A review of operating history did not identify any previous events related to this event.