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Constellation Shuts Calvert Cliffs Nuclear Plant for Work

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Nov. 27 (Bloomberg) -- Constellation Energy Group Inc. shut the 873-megawatt Calvert Cliffs 1 reactor in Maryland for unplanned work on control element assemblies.

Extensive monitoring at the unit, which slowed to 45 percent of capacity early today and halted as of 8:37 a.m,, showed “traces of electrical noise” with one of the coils in the No. 37 assembly, said Kory Raftery, a plant spokesman. Crews are replacing the coils and conducting more tests on all assembly equipment, he said.

“We need to make sure our operators can control every piece of equipment at the plant,” Raftery, who is based at the plant, said in a phone interview today.

Constellation has been monitoring electrical coils at Unit 1 since the summer, when the equipment failed and caused a reduction in output, Raftery said. The coils hold up control rods and allow operators to insert those rods into the core to slow or boost output.

Calvert Cliffs Unit 2 continues to operate at full power. The plant is about 38 miles (61 kilometers) south of Annapolis, Maryland.

To contact the reporter on this story: Christine Harvey in New York at

To contact the editor responsible for this story: Dan Stets at