The team identified a violation of
10 CFR 50, Appendix B, Criterion III, Design Control, for installing and modifying electrical protection and monitoring circuits that did not meet the general design criteria for single active failures. A common electrical protection and metering circuit was installed such that a single active failure of a component in the circuit could trip and lock out all feeder breakers to both 4160V
ES busses, resulting in a loss of all safety-related alternating current power. This finding was an immediate safety concern and the licensee made modifications to correct the nonconforming condition before the inspection team left the site. This finding is unresolved pending the completion of a significance determination. The finding is greater than minor because it is associated with the design control and equipment performance attributes of the reactor safety
mitigating systems cornerstone. The finding adversely affects the objectives of availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences.
