(Reuters) - A welder's torch ignited a small fire on the roof of a building at a nuclear research laboratory in Idaho on Monday, prompting an evacuation, but no one was hurt and no radioactive material was involved, lab officials said.
Nearly 100 employees were cleared from the building, part of a complex that includes facilities housing spent nuclear fuel and radioactive waste at the Idaho National Laboratory, the U.S. Energy Department's leading facility for nuclear reactor technology.
The fire damaged 4 square feet (0.4 square meter) of the roof and was extinguished about 2-1/2 hours after smoke was first detected, the lab said in a statement.
No radioactive material was affected or involved in the fire, and there was no release of radiation, the lab said.
The complex of buildings where the fire erupted sits near the edge of the sprawling 890-square-mile lab site in the high desert of eastern Idaho, about 38 miles from the city of Idaho Falls.
In November 2011, 16 Idaho lab workers in an adjacent building were exposed to radiation during an accident that occurred while they were preparing to remove an old plutonium fuel cell from a decommissioned reactor.
The building whose roof caught fire on Monday houses research laboratories but no spent fuel or radioactive waste, lab spokeswoman Misty Benjamin told Reuters.
Several thousand employees and contractors work at the Idaho National Laboratory, the U.S. Energy Department's leading facility for nuclear reactor technology.
(Reporting by Laura Zuckerman; Writing by Steve Gorman; Editing by Dan Burns, Eric Walsh and Lisa Shumaker)