Deviation related to upper stud assemblies for General Electric Nuclear AKR-30 low voltage circuit breakers. The deviation is specific to upper stud assemblies supplied under part number Q139C4632G1 and consist of an incorrect angle between the stud and pivot. Of the fifteen assemblies supplied with possible deviations to AmerenUE, five were returned and ten had been installed in Callaway Plant. The deviation will not prevent the circuit breakers from performing their design basis function at the Callaway Plant, however, the capability of the assemblies is indeterminate for severe faulted conditions. A circuit breaker could fail if an upper stud assembly with identified deviation was installed and the circuit breaker was called upon to interrupt a severe fault.
Callaway has concluded that this deviation does not constitute a "defect" as defined in 10CFR Part 21 because the breakers would still perform their design basis requirements and would not create a substantial safety hazard. However, Callaway can not determine if the potential for a significant safety hazard or exceeding of a technical specification safety limit could exist at another nuclear power plant.
Received written documentation that the licensee has notified the NRC resident inspector.
