The Department of Energy has closed the main plutonium processing facility at the Rocky Flats nuclear weapons plant, but no one has been exposed to radiation, a plant spokesman said Tuesday.

The department ordered Building 771 closed Saturday but allowed the rest of the plant to continue operations, according to officials of the DOE and Rockwell International, which operates the plant.It was the second time in two months the agency has suspended production at a major nuclear facility. In August, the department ordered a production shutdown at the Savannah River Plant in South Carolina because of safety problems.

The New York Times said an accident at Rocky Flats had exposed some employees to radiation contamination, but Rockwell spokesman Pat Etchart said that was not true.

"There was no contamination," Etchart said. "There was a potential contamination incident."