Baltimore, August 29, 2011 — The Calvert Cliffs Nuclear Plant Unit 1 operated by Constellation Energy Nuclear Group automatically went off line late August 27 after a piece of aluminum siding propelled by wind gusts hit the nuclear facility's main transformer. Calvert Cliffs Unit 2 remains at 100 percent power.
All safety systems operated as designed when Unit 1 automatically went off line. As required by federal regulations, CENG declared an Unusual Event at 11:02 p.m., August 27; a UE is the lowest of four emergency classifications established by the U.S. Nuclear Regulatory Commission. The UE presents no threat to public health or safety.
A review of the grounds at the Calvert Cliffs facility in Lusby, Md., indicated that a gust of wind associated with Hurricane Irene dislodged a piece of aluminum siding from a building, and the siding then struck the main transformer. Plant personnel were continuing comprehensive site reviews today as specified in the Calvert Cliffs emergency response plan.
A CENG fleet structure team has been activated to ensure necessary support at all CENG locations impacted by the storm. CENG's two New York nuclear facilities, R.E. Ginna and Nine Mile Point, remain at full power today. All CENG facilities have emergency safety procedures in place, which include early and extensive preparation for storms.