The truck that caught fire a half mile underground at a southeastern New Mexico nuclear waste dump was 29 years old, improperly maintained and operating without an automatic fire-suppression system, according to a report.
The report to be released Friday also will detail deficiencies in emergency training and responses at the Waste Isolation Pilot Project (WIPP) near Carlsbad.
"It was preventable," Ted Wyka, a Department of Energy official who led the investigation, told a community meeting on Thursday evening.
Wyka previewed the findings of the probe into the first of two back-to-back incidents at the federal government's only permanent repository for waste from the nation's nuclear bomb-building facilities.
An investigation of a radiation release nine days later that contaminated 17 workers is expected in a few weeks.
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The report was previewed just hours after the contractor that runs the site confirmed it had demoted WIPP President Farok Sharif.
Wyka said the investigation of the truck fire did not reveal exactly what sparked the blaze, but he said the old truck that was hauling salt had a build-up of oil and other combustible materials as well as active leaks.
The fire probably started about 30 minutes before the driver saw the orange glow from the engine compartment and jumped out to try to extinguish it, he said. But the automatic fire-suppression system that might have detected the heat earlier was not active, Wyka said, and the fire extinguisher the driver sprayed on the truck apparently didn't work.
While Wyka praised the 86 workers who were underground when the fire started on February 5 for their response, he said a number of systems failed. For example, he said emergency strobe lights were not activated for five minutes, the command-centre response was lacking and the investigation showed emergency training drills were inadequate.
Six workers were treated for smoke inhalation after the fire.
WIPP is the nation's only deep underground nuclear waste repository and a cornerstone of the Energy Department's $US5 billion ($A5.56 billion)-a-year program for cleaning up waste scattered at federal labs across the country from decades of making nuclear bombs.
