28 Apr (NucNet): An incident that resulted in the release of radioactive material from the US Department of Energy’s Waste Isolation Pilot Plant in New Mexico earlier this year could have been prevented, a DOE accident review board report has concluded.
The incident happened on 14 February 2014 in the underground repository at the WIPP near Carlsbad, New Mexico. It resulted in the release into the environment of americium and plutonium from one or more transuranic (TRU) waste containers.
The WIPP is a deep geologic repository, mined out of a thick bed of salt, for the disposal of defence TRU waste generated primarily from the cleanup of DOE sites and from research and production of nuclear weapons.
The release was detected by an underground air monitor and then directed through particulate air filter banks in the surface exhaust building.
However, a measurable portion bypassed the filters through two ventilation system dampers and was discharged directly to the environment from an exhaust duct.
The dampers were not designed to be airtight, the report said. The confinement ventilation system had been considered “safety significant” until a change in 2008 reduced its classification to “balance of plant”, meaning it was no longer considered to be needed to protect workers from radiological accidents, the report said.
The report said the WIPP contractor, DOE headquarters and the department's field office in Carlsbad, New Mexico, as well as outside organisations, missed opportunities to identify that inadequacy in the safety basis for the ventilation system.
The direct cause of the release could not be determined because of a lack of access to the underground area in question, the report said. That question will be resolved in a second phase of the board’s investigation, it said.
Twenty-one personnel initially tested positive for low level amounts of internal contamination. Trace amounts of americium and plutonium were detected off-site.
