At least six workers are suffering from low-level plutonium radiation exposure and 11 others also had a dose at a U.S. nuclear research lab in Idaho.
While the workers suffered the exposure, the public was not at risk, the government said.
The mishap at the Idaho National Laboratory occurred inside a deactivated reactor housed in a facility used for remotely handling, processing and examining spent nuclear fuel, radioactive waste and other irradiated materials, the lab said.
The Materials and Fuels Complex is near the edge of the U.S. Energy Department’s sprawling 890-square-mile laboratory site in the high desert in eastern Idaho about 38 miles from Idaho Falls.
But lab bulletins on the mishap, believed to be the most serious accident at the site in at least four years, said there was no evidence of a release of radiation outside the facility, and “there is no risk to the public or environment.”
Seventeen 17 technicians, all employees of lab contractor Battelle Energy Alliance, were working inside the decommissioned research reactor when “a container was opened for normal, scheduled work, resulting in low-level worker exposure to plutonium,” the lab 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 said the exposed workers were working 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.
Workers were able to confine the contamination to the room where they detected it, and they evacuated and sealed the room. Workers elsewhere in the reactor building ended up evacuated as a precaution, officials said.
The exposed workers underwent initial decontamination procedures at the complex before they went to a medical facility elsewhere on lab grounds for further evaluation, the lab said.
Six of those exposed initially tested positive for low levels of contamination detected on their skin and clothing, Johnson said. All 17 were undergoing full-body scans to determine how much of a radiation dose they really received, lab officials said.
The workers received treatments designed to speed their bodies’ elimination of any contaminants ingested or inhaled, including intravenous fluids with calcium or zinc to bind radioactive particles before expelling them from the body.
Details about the condition of the workers were not immediately available and the lab said it may be weeks before they know the full extent of exposure and contamination. The effects of radiation worsen the longer radioactive material remains in the body.
Johnson said the “zero power physics reactor” where the accident occurred ended up decommissioned in 1992 and officials used it to study and test technology for space and commercial nuclear reactors. The plutonium at issue in the accident was in leftover reactor fuel, he said.