Of the 93 U.S. power reactors currently in operation, 91 are in the top performance category of the NRC’s five-category action matrix, Licensee Response. Two reactors—Ameren Missouri’s Callaway and Energy Harbor’s Davis-Besse—are in the second category, Regulatory Response. For reactors in that category, NRC oversight includes additional inspections and follow-up of corrective actions.
Underperformers: The NRC informed Ameren early in 2021 that Callaway—a 1,194-MWe pressurized water reactor in Fulton, Mo.—had been moved to Regulatory Response as a result of having three unplanned scrams during the second through fourth quarters of 2020, combined with having lower than normal hours of critical operation for the year.
Davis-Besse—a 908-MWe PWR located in Oak Harbor, Ohio—was moved to the Regulatory Response category last year due to a greater-than-green finding (meaning a finding of more than very low safety significance) identified by NRC personnel during a scheduled cybersecurity inspection. In addition, more recently, the NRC issued Energy Harbor a violation notice involving the failure to select a suitable replacement part for Davis-Besse’s emergency diesel generator speed switch. The speed switch design was not compatible with the station’s 125/250 volt direct current battery system, according to the agency.
