05000458/LER-2001-003

LER-2001-003,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv)(A), System Actuation
4582001003R00 - NRC Website

EVENT DESCRIPTION

On September 24, 2001, the station was in a refueling outage, and scheduled surveillance testing of the Division I emergency core cooling systems (ECCS) was being conducted. Prior to 6:00 a.m.

CDT, the service water supply to the drywell unit coolers (**CLR**) was secured, realigning the systems to a chilled water supply to improve habitability for workers in the area until the ECCS test could be performed. Setup for the ECCS test continued while the system was in this configuration.

As part of the test setup, an operator was required to verify the position of four motor-operated service water valves. Two Division I valves (**ISV**) were to be verified open, and two Division II valves were to be verified closed. This test alignment separates the two divisions of service water through this cross-tie. When the operator initially performed this verification, all four motor-operated valves were closed due to the chilled water lineup. The operator verified the two Division II valves closed and flagged the two Division I valves so that verification could be performed when the service water lineup was restored just prior to the actual test initiation.

When plant conditions supported performance of the ECCS test, the operating crew realigned service water to the drywell coolers using the system operating procedure to restore the system. At the completion of this realignment, the two Division I valves were verified to be open as required by the ECCS test procedure. The test director did not recognize that the two Division II valves that had previously been verified closed were reopened as part of this operation. As a result, all four motor- operated valves were open, and the service water system cross-tied through the drywell unit coolers when other automatic valve actions occurred as expected during the test. When the test was initiated at approximately 4:55 p.m., a low pressure condition was momentarily induced in the standby service water system. The Division II standby service water system responded as designed to the low pressure condition. After an initial assessment, it was restored to its correct configuration, and the ECCS test proceeded.

CAUSAL ANALYSIS AND IMMEDIATE CORRECTIVE ACTION

The surveillance test procedure is extensive, and is written to allow performance in a number of various plant configurations. The test procedure itself contains no detailed provisions for tracking changes to affected plant components once their pre-test configuration is set. The test director relied on active monitoring of crew activities to identify configuration changes that could impact test conditions, and missed these two valves. No tool was used to identify verified test components so that all operators manipulating could assist in maintaining the appropriate test configuration.

The lessons learned from the Division I test were incorporated into the crew briefing for the Division II test conducted later in the outage.

CORRECTIVE ACTION TO PREVENT RECURRENCE

The ECCS test is a complex test that requires several hours to prepare and involves a broad cross- section of plant components. This complexity and the extended time duration of the test create a unique error-likely situation for operators and test participants. Recognizing this, the following action will be taken to prevent recurrence:

• Guidelines will be implemented to provide a clear visual identification of components that have been verified to be correctly positioned for the test.

This action is scheduled to be completed by April 1, 2003, and will provide a mechanism to alert operating personnel when plant operations require these components to be manipulated. They can then ensure that the component is restored in accordance with plant procedures and that the impact on test activities is appropriately evaluated.

PREVIOUS OCCURRENCES

A search of River Bend's Licensee Event Reports since January 1995 found no similar previous events.

SAFETY SIGNIFICANCE

This event was of minimal significance with respect to the health and safety of the public. The reactor was in cold shutdown at the time of the event, and the Division II standby service water system responded as designed. No loss of safety function occurred.

(Note: Energy Industry Identification codes are annotated in the text as ("XXX"))