IDAHO FALLS, Idaho (AP) — Federal officials have reported a radiation accident six months after it happened at the Idaho National Laboratory in eastern Idaho.

The Post Register reports that the U.S. Department of Energy reported the radioactive contamination of one worker during a presentation last week at an INL Site Environmental Management Citizens Advisory Board's meeting in Pocatello.

Officials say the Oct. 23 accident happened at the New Waste Calcining Facility operated by contractor CH2M-WG Idaho and led to a work stoppage that lasted weeks.

Officials say the accident occurred following a mistake in the process as workers attempted to repackage radioactive waste.

Officials say workers evacuated after monitors sensed airborne radioactivity.

A CH2M-WG Idaho spokesman tells the Idaho Falls newspaper that one worker received internal contamination equivalent to a chest X-ray.