05000395/LER-2003-005

LER-2003-005, Failure of Master Relay K507 During Solid State Protection System Testing

Docket Number
Event date:	10-03-2003
Report date:	12-15-2003
Reporting criterion:	10 CFR 50.73(a)(2)(vii), Common Cause Inoperability
3952003005R00 - NRC Website

PLANT IDENTIFICATION

Westinghouse - Pressurized Water Reactor

EQUIPMENT IDENTIFICATION

Solid State Protection System Master Relay K507

IDENTIFICATION OF EVENT

This event was identified during performance of Surveillance Test Procedure (STP) 345.037, Solid State Protection System Actuation Logic and Master Relay Testing. Master Relay K507 failed to actuate during the test. This condition was identified in Condition Evaluation Report (CER) 03-3099 as a Non-Conforming condition.

EVENT DATE

October 3, 2003 (Date of determination of significant safety hazard - December 1, 2003)

REPORT DATE

December 15, 2003

CONDITIONS PRIOR TO EVENT

The plant was in Mode 1, at 100% Power.

DESCRIPTION OF EVENT

On October 3, 2003, the V. C. Summer Nuclear Station (VCSNS) was performing solid state testing on the 'A' train. The testing is in accordance with Surveillance Test Procedure (STP) 345.037, Solid State Protection System Actuation Logic and Master Relay Testing. At 1300, Master Relay K507, which actuates the Feed Water Isolation circuits upon HVHi Steam Generator Water Level, failed to actuate. This component was a master relay with a paper wrapped coil, manufactured by MidTex (part number [P/N] 156-14D200). MidTex has no address, as they are no longer in business.

A Non-Conformance Notice (NCN 03-3099) was written, and the master relay was replaced on October 3, 2003.

The affected master relay was sent to Pentas, Inc. for a Root Cause of Failure Analysis.

The failure analysis results attributed the failure to be an open circuit in the coil resulting from corrosion caused by off-gassing of chlorine contamination from the paper used to wrap the coil, or the adhesive used to attach the paper to the coil. 'Another MidTex P/N 156-14D200 relay with a paper wrapped coil, sent to Pentas, Inc. for follow-up analysis, showed evidence of the same type of corrosion. Therefore, this failure is considered to be a manufacturing defect in a basic component, which could cause a loss of safety function.

An investigation into other master relays at VCSNS revealed that three additional MidTex P/N 156-14D200 master relays with paper wrapped coils were installed in 'A' Train Solid State Protection System cabinet XPN7010. Although none of these had actually failed, they were replaced with Potter & Brumfield relays during Refueling Outage 14 (November 2003). The majority of the MidTex P/N 156-14D200 relays installed at VCS have cloth wrapped coils, and showed no evidence of corrosion.

This event is being reported under 10 CFR 50.73(a)(2)(vii) and 10 CFR 21.21.

ANALYSIS OF EVENT

Although the redundant train for K507, which had a different type of master relay, was operable and could have actuated the Feed Water Isolation Valves on a HUHi Steam Generator Water level, VCSNS has determined that this condition should be reported under 10 CFR 50.73(a)(2)(vii), since multiple components were potentially affected in various trains and systems by the corrosion due to off-gassing.

CORRECTIVE ACTIONS

The potentially affected master relays have been identified and replaced with Potter & Brumfield relays.

PRIOR OCCURRENCES

None