NRC requires that the Wolf Creek nuclear power plant have emergency diesel generators that must be tested monthly to ensure operability. During one test, an emergency generator started as required, but failed three hours into a 24-hour run because of a faulty electrical component. The event did not pose an immediate safety concern because there are other backup emergency power supplies. The generators are used to supply power to safety-related systems in the event of a loss of off-site power.
Repairs have been made to the faulty diesel generator and a preventive maintenance strategy has been developed. The NRC preliminarily determined that the inspection finding has low to moderate, or white, safety significance. The finding may require additional inspections, regulatory actions and oversight. The final safety significance of the finding or any additional NRC actions will be decided at a later time.
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