The Nuclear Regulatory Commission last week cited Ohio’s Davis-Besse nuclear power plant for improper maintenance of its very large emergency diesel generators (EDGs), which are used only when the reactor fails and the plant is cut off from outside grid power.

The EDGs must start immediately and be able to produce full power in as quickly as 10 seconds in order to enable emergency pumps and other equipment to continuously cool the reactor’s nuclear core to prevent it from overheating.

NRC determined that plant engineers installed improper replacement parts that prevented the plants’ two EDGs to immediately start during routine testing. Along with a lack of maintenance of other components essential to the production of power, it was enough to be a safety violation, rather than a minor infraction.

The citation — on top of an earlier NRC finding that Davis-Besse violated cybersecurity protocols — puts the plant under increased inspections in the coming months. The commission does not specify the severity of cybersecurity violations or the level of the citation it issues in such cases.

Davis-Besse, operated by a FirstEnergy subsidiary until it emerged from federal bankruptcy protection in early 2020, is today owned by Energy Harbor, a closely held company that does not respond to media inquiries. The plant is currently shut down for refueling, according to NRC.