NRC inspects Calvert Cliffs Nuclear Plant after power disturbance

Following an April 7 incident at the Calvert Cliffs Nuclear Plant in southern Maryland, the Nuclear Regulatory Commission dispatched a three-member team Monday to review and assess equipment response.

Operated by Exelon, both reactors at the Lusby-located plant experienced an unplanned shutdown due to a transmission-related grid disturbance. The reactors are designed to automatically shut down in such an event.

Subsequent to the grid disturbance, two equipment units faltered in the plant’s Unit 2, One of three saltwater pumps did not automatically restart when the power switched to the emergency generators, and an emergency diesel generator started but failed after 11 seconds. This latter unit also failed to restart after a power loss in 2010.

As per standard procedure, operators started the pump manually in order to provide cooling water to equipment.

“While there was no impact on public health and safety, the issues with the emergency diesel generator and the saltwater pump warrant a closer look,” NRC Region I Administrator Dan Dorman said.

The team sent to examine the event will develop a sequence of tasks including reviewing and evaluating equipment response, appraising operator performance, and assessing Exelon’s response in terms of effectiveness. A report documenting the team’s findings will be forthcoming within 45 days of the inspection’s culmination.