The NRC told Ameren early in 2021 that Callaway-1, a 1,215-MW pressurised water reactor in Missouri that began commercial operation in December 1984, had been moved to the “regulatory response” category 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-1, an 894-MW PWR in Ohio that began commercial operation in July 1978, 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.
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 NRC.