WESTINGHOUSE ELECTRIC COMPANY: POTENTIAL EXISTENCE OF DEFECTS IN SHIELD PASSIVE THERMAL SHUTDOWN SEAL SYSTEM

The defect being reported concerns an identified inconsistency between the intended design functionality of the SHIELD passive thermal shutdown seal (SDS) and that observed during post-service testing.

The purpose of the SDS is to reduce current reactor coolant system inventory losses to very small leakage rates for a plant that results in the loss of all reactor coolant pump (RCP) seal cooling. The SDS is a thermally actuated, passive device integral to the RCP Number 1 seal insert and is positioned between the Number 1 seal and the Number 1 seal leak-off line to provide a near leak-tight seal once activated.

The SDS has only been delivered and installed in the following plants: Beaver Valley Unit 2, Callaway, D.C. Cook Unit 1, Farley Units 1 and 2, and Wolf Creek.

Westinghouse has concluded that the hardware itself will not adversely impact safe plant operation.

Affected customers have been informed via their respective Customer Project Managers of the post-service test failure.
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