The U.S. Nuclear Regulatory Commission (NRC) staff has determined that an inspection finding at the 1,200 MW Wolf Creek nuclear power plant in Burlington, Kan. is of “yellow,” or substantial safety significance.
The “yellow” finding moves Wolf Creek into the “degraded cornerstone” column of the action matrix, resulting in a higher level of NRC oversight.
A main generator electrical breaker failed on Jan. 13, causing a loss of power at the plant and then at the switchyard, which removed the plant’s connection to the power grid. All safety systems responded as expected and emergency diesel generators powered safety-related equipment.
The NRC conducted an Augmented Inspection and determined that plant operator Wolf Creek Nuclear Operating Corp. (WCNOC) failed to provide adequate oversight of contractors while they performed work in April 2011 that could affect safety-related equipment. As a result, WCNOC did not identify that electrical maintenance contractors had improperly connected wires on an electrical component, which allowed an electrical short to prevent transfer of power to a transformer during the January incident.
Subscribe to Nuclear Power International magazine