DENVER — Enough plutonium to build seven nuclear bombs has escaped into the air ducts of the federal government's Rocky Flats nuclear weapons facility here over the last 38 years, federal officials said.
The 62 pounds of plutonium is spread throughout 6,000 feet of air ducts and "does not pose a health risk to workers at the plant or to public health," said Pat Etchart, a spokesman for the Department of Energy.
Etchart said Thursday that the plutonium in the ducts is less than might be expected after 30 years of operations at the plant.
But critics of the troubled plant, which was raided in June by FBI agents investigating possible environmental crimes, said the discovery raises even more serious questions about the plant's operation.
"This is very serious when you consider that people in the nuclear weapons business are concerned when grams of this stuff turn up missing," said Jim Werner, a spokesman for the Natural Resources Defense Council. "It also raises serious questions about the accountability of the people in control."
The discovery contrasted sharply with an earlier estimate that from 10 to 33 pounds of plutonium had escaped into the ducts from "glove boxes" used to shield plant workers handling radioactive material.
The lower estimate was made by a special team of investigators formed after the FBI raid, which determined that workers had for years unclogged "prefilters" in the glove boxes by punching holes in them with screwdrivers, federal officials said.
Plutonium operations at the plant, which makes triggers for hydrogen bombs, were halted in November until a contractor in charge of the facility can ensure that safety concerns are met. The plutonium operations are expected to be resumed this summer, federal officials said.
Times researcher Ann Rovin contributed to this story.