The US Nuclear Regulatory Commission (NRC) has begun a special inspection at the Calvert Cliffs nuclear power plant (NPP) in Maryland, to further review an unplanned shutdown of both reactors last week.

The three-member NRC team will evaluate what happened during the event, including the response by plant operators and safety systems, and will also examine the event’s causes and any related issues.

The inspection will expand on initial assessments performed by the two NRC inspectors.

NRC Region I Administrator Bill Dean said the team want to gain a better understanding of the chain of events that led to simultaneous shut down of both reactors and equipment anomalies subsequent to the plant trips.

”This inspection is designed to shed additional light on not only why the outages happened but how the plant operators handled them,” Dean added.

The automatic shutdown was initially attributed to tripping of a 4kV electrical bus connected to components on both units.

Operated by Constellation Energy Nuclear Group (CENG), he Calvert Cliffs nuclear plant has two 2700MW thermal (MWth) Combustion Engineering Generation II two-loop pressurized water reactors (PWR), and produce over 1,700MW of electricity, which power more than one million homes.