United States government investigators have uncovered a series of shortcomings in safety training, emergency response and oversight at a troubled nuclear waste dump where a truck caught fire and 17 workers were recently contaminated by a radiation leak.
A report on the investigation into the first of back-to-back accidents at the waste isolation pilot plant (Wipp) near Carlsbad in the state of New Mexico says a February 5 truck blaze was apparently ignited by a build-up of oil and other combustible materials that should have been regularly cleaned off the vehicle.
The truck was also operating without an automatic fire suppression system, the Department of Energy report said. And one of several mistakes made in the chaotic moments that followed switched the filtration systems in the mine 800 metres underground and sent smoke billowing into areas where workers expected to have "good air".
The report also identified problems with the safety culture at the federal government's only permanent repository for waste from the nation's nuclear bomb-building facilities, and it said a series of repeat deficiencies identified by an independent oversight board had gone unresolved.
Tom Udall and Martin Heinrich, the US senators from New Mexico, called the report "deeply concerning".
"Fortunately, no one was hurt," the senators said in a statement. "The community of Carlsbad and the nation expect Wipp to operate with the highest level of safety.
"The board has identified a number of serious safety concerns that will need to be fully addressed. We believe all levels of management at the Department of Energy and at Wipp must take the recommendations from the board very seriously and fully implement them."
Congressman Steve Pearce, whose district includes the plant, applauded the DOE for a transparent report that highlights "the sloppy procedures that caused the fire".
An investigation of a radiation release nine days later that contaminated 17 workers and sent toxic particles into the air around the plant is expected to be completed in a few weeks.
The mine has been shut since the February 14 release, but investigators hope to be able to get below this week to see what happened.
The accidents are the first major incidents at the repository, which began taking radioactive waste 15 years ago.
Just hours before the report on the truck fire was previewed at a community meeting on Thursday evening, the contractor that runs the the plant demoted the facility's president.
The official who led the investigative team, Ted Wyka, said the automatic fire-suppression system that might have detected the heat earlier was not active.