Irene takes two nuclear plants offline

Hurricane Irene — which was downgraded to a tropical storm Sunday — has prompted the shutdown of nuclear reactors in Maryland and New Jersey.

In Maryland, one reactor at Constellation Energy’s Calvert Cliffs plant automatically went offline late Saturday because a wind gust propelled a piece of aluminum siding from a building into the facility’s main transformer.

Constellation declared an “unusual event,” which is the lowest of four Nuclear Regulatory Commission emergency classifications. The plant’s other reactor remains online.

In New Jersey, Exelon Corp. took the one-reactor Oyster Creek Generating Station offline Saturday as a precaution ahead of expected high winds from the storm.

NRC spokesman David McIntyre told The Hill on Sunday that it could be a couple of days before the plants are brought back online.

“There are all sorts of checks that have to be made before they can come back,” he said. “I don’t want to put a timeframe on it.”

In addition to the plants that are offline, Progress Energy’s Brunswick nuclear plant in North Carolina and Dominion’s Millstone nuclear plant in Connecticut were operating at reduced power as a precaution ahead of the storm.

The NRC, in anticipation of the storm, dispatched extra inspectors to nine plants in North Carolina, Maryland, New Jersey, Connecticut, Massachusetts, New Hampshire and New York. Click here for our story about the NRC’s preparations.