(CNN) -- At least 17 employees at the Idaho National Laboratory were exposed Tuesday to what the lab described as low-level radiation from plutonium.
The workers underwent initial decontamination at the facility where the incident happened and were then transported to an on-site medial center for evaluation, the lab said in a statement.
There is no evidence of a leak outside the facility and there is no risk to the public or environment, it added.
The Idaho National Laboratory (INL), located in eastern Idaho, is a U.S. Department of Energy nuclear research site.
Tuesday's incident happened within the lab's materials and fuels complex, which has facilities for remotely handling, processing and examining spent nuclear fuel, irradiated materials and radioactive wastes, according to the INL's website.
The workers were inside the decommissioned Zero Power Physics Reactor (ZPPR) when a container was opened for scheduled work, "resulting in low-level worker exposure to plutonium," the lab said. The ZPPR was a low-power test reactor that evaluated various design features.