Failure of Master Relay K507 (MidTex Part Number 15614D200) in the Solid State Protection System (SSPS) was attributed to corrosion caused by off-gassing of
chlorine contamination from paper used to wrap the relay coil, or the adhesive used to attach the paper wrap to the coil. Master Relays must change state, upon energization, to actuate various safety related equipment in the plant. The failure of Master Relay K507 is considered to be a manufacturing defect in a
basic component that could cause a loss of safety function.
The majority of MidTex relays investigated had cloth wrapped coils and these relays showed no evidence of corrosion.
The number of affected relays and installed locations was not available at the time of the initial notification.
The licensee will notify the NRC Resident Inspector.