The US Nuclear Regulatory Commission (NRC) is investigating a leak of uranium hexafluoride, UF6, at a uranium conversion facility in Illinois.
Honeywell International Inc, the company operating the uranium plant in Metropolis, confirmed the leak on Sunday and said it was due to an equipment failure.
NRC spokesman Roger Hannah said an inspector was dispatched to the plant on Tuesday and that the investigation could take a few days.
“At this point we’re still in a fact-finding mode,” Hannah said. “We haven’t come to any conclusions about whether processes weren’t followed.”
Members of the public reported a cloud emanating from the plant for five minutes, the NRC said in a report.
No injuries have been reported and the plant is still operating.
“There were no injuries and no indication that any UF6 material left the site,” company spokesman Peter Dalpe said, according to Reuters.
When exposed to water vapor, uranium hexafluoride breaks down into hydrofluoric acid and uranyl fluoride, both of which are highly toxic.
The leak comes at a time when Honeywell and union workers are embroiled in a contract dispute in the plant where employees have been locked out since August.
The Metropolis plant is the only US facility that converts uranium oxide into UF6, which is then enriched to nuclear fuel.