An NRC statement said the closures were ordered because of "grid instabilities," but added that "all plants are in a safe condition, using their emergency diesel generators where appropriate."

NRC resident inspectors "will continue to monitor the situation at the affected plants," the statement read.

It named the closed plants as Indian Point, Ginna, Fitzpatrick and Nine Mile Point in New York state, Perry in Ohio, Fermi in Michigan and Oyster Creek in New Jersey.

WAR.WIRE