No contamination reported outside affected facility
The fire broke out Wednesday at the Savannah River National Laboratory in Aiken, South Carolina. The emergency was declared at 5:39 p.m., and the fire was then extinguished.
The emergency response shut down incoming traffic and restricted air and rail service in the area.
Employees in areas affected by the fire who were not involved in the response were sheltered, the site statement said. The statement also said no contamination was reported outside the affected facility.
The laboratory occupies the northwest corner of the Savannah River Site, a federal complex where the government once produced materials used in nuclear weapons. The materials were primarily tritium and plutonium-239.
The site was opened in the early 1950s to manufacture the plutonium pits needed for nuclear-bomb cores at the start of the Cold War with the Soviet Union.
Today it is used for environmental stewardship and cleanup, along with nuclear waste management and disposition of nuclear materials, according to the U.S. Department of Energy.