05000397/LER-2003-004

LER-2003-004,

Docket Number
Event date:	06-08-2003
Report date:	08-07-2003
3972003004R00 - NRC Website

Event Description

On June 3, 2003, with the reactor shutdown in mode 4 and the mode switch in the refuel position, a condition prohibited by the Columbia Generating Station Technical Specifications existed. Specifically, Function 7.a of Table 3.3.1.1-1 was not operable as required by special operations Limiting Condition for Operation (LCO) 3.10.4.c. 1 . Function 7.a of Table � 3.3.1. is the-transmitter/trip-Mit Instrumerilatioif � al=n-E—laslitractortr-rolaTili System (RPS) trip on high Scram Discharge Volume (SDV) water level. This requirement of LCO 3.10.4 was not met because the transmitter/trip unit instrumentation on both SDVs was isolated in support of an SDV flushing procedure that was not in progress at the time. Special operations LCO 3.10.4 permits withdrawal of a single control rod for testing or maintenance and may be applied when the reactor is in cold shutdown. This LCO allows placing the reactor mode switch in the refuel position to enable the single control rod withdrawal permissive in order to perform control rod scram timing pursuant to Technical Specifications Surveillance Requirement 3.1.4.1 prior to reactor startup.

Immediate Corrective Action Upon discovery that all requirements of LCO 3.10.4 were not met, plant operators exited the condition of applicability for LCO 3.10.4. All control rods were inserted into the reactor core and the mode switch was placed in the shutdown position preventing control rod withdrawal.

Additionally, the SDV water level transmitter/trip unit instrumentation was restored to service and a night order documenting this event and lessons learned was transmitted to all operating crews.

—4011111Plaill The cause of the condition prohibited by Technical Specifications is

• attributed to human performance errors. These errors occurred during preparation of the procedure used for the SDV flushing activity and in assessing the impact of the flushing activity upon compliance with LCO 3.10.4.

Further Corrective Action This event will be reviewed with all operations personnel and pre-job planners to convey the importance of thorough pre-job review of the scope of maintenance activities and assessment of Technical Specifications requirements when maintenance activities are performed.

Assessment of Safety Consequences

No safety consequences were associated with the condition prohibited by Technical Specifications and plant operators would have been alerted to increasing water level in the SDVs. As the water level in the SDV increases, a control room alarm is actuated followed by control rod withdraw block and a reactor scram. These functions would have been initiated by redundant SDV float switchesILSRILLI stioL.b of Table-31,1.1J.L.that_ were_nperahle_ta_-- pro iv the RPSi—nli on high SDV level as required by LCO 3.10.4. The condition prohibited by Technical Specifications existed for approximately 5.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> during which time testing was performed on four control rods. The SDV is sized to receive and contain all of the water discharged by 185 control rod drives during a reactor scram. Because scram testing was performed on only four control rods, considerable margin existed to the water level at which alarms or automatic safety functions are initiated.

Similar Events On May 2, 2001, Licensee Event Report 2001-002 reported a condition prohibited by Technical Specification LCO 3.3.1.1 existed due to a human performance error. This occurred when an SDV float switch instrument channel was not returned to service after performance of a 92-day Channel Functional Test.

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