SALMON, Idaho Seventeen workers were exposed to low-level radiation from plutonium on Tuesday at a U.S. Energy Department nuclear research lab in Idaho, but there was no risk to the public, the government said.
The accident at the Idaho National Laboratory occurred inside a facility used for remotely handling, processing and examining spent nuclear fuel, radioactive waste and other irradiated materials, the lab said in a series of statements.
The so-called Materials and Fuels Complex is located near the edge of the sprawling 890-square-mile laboratory site in the high desert in eastern Idaho about 38 miles from the city of Idaho Falls.
But the lab's latest bulletin on the mishap said there was no evidence of a release of radiation outside the facility, and "there is no risk to the public or environment."
At least 17 employees were working inside a decommissioned research reactor when "a container was opened for normal, scheduled work, resulting in low-level worker exposure to plutonium," the statement said.
There were no immediate details from the lab on the precise cause or nature of the radiation release, such as whether it resulted from an equipment malfunction or human error.
Lab spokesman Earl Johnson told Reuters the exposed workers were engaged in an activity and in an area that required no special protective shielding.
"We certainly didn't expect this to happen," he said, adding that radiation-control technicians monitoring the area detected the low-level release.
Johnson said the "zero-power physics reactor" where the accident occurred was decommissioned in 1992 and had been used to study and test technology for space and commercial nuclear reactors.
The exposed workers underwent initial decontamination procedures at the complex before they were taken to a medical facility elsewhere on the lab grounds for "further evaluation," the lab said. Details of their condition were not immediately provided.
Some 6,000 employees and contractors work at the Idaho National Laboratory, the Energy Department's leading facility for nuclear reactor technology.
According to lab records, Tuesday's incident appeared to be the most serious accident at the lab since June 2007, when a worker was treated for minor burns and smoke inhalation from a small laboratory fire, though no radiation release was reported in connection with that mishap.
It was too early to say how serious Tuesday's accident was compared to previous mishaps "since we don't yet know what the consequences of the accident will be," said Liz Woodruff, head of a private, nonprofit nuclear watchdog group in Idaho called the Snake River Alliance.
But, she said, "These are a lot of workers."
(Reporting by Laura Zuckerman; Writing by Steve Gorman; Editing by Cynthia Johnston)