A federal oversight board says Los Alamos National Laboratory has significantly underestimated how much radiation could leak from its main plutonium lab in the event of a major earthquake and fire.
The Defense Nuclear Facilities Safety Board says it has "identified a number of deficiencies" in calculations that concluded any release would be below the threshold deemed safe to the public.
Board staff say their calculations indicate the potential for a radiation release from a seismically induced fire could instead be more than four times that level.
At issue are the lab's efforts to shore up the 1970s-era facility known as PF-4, which is the nation's primary center for working with the dangerous plutonium used in nuclear weapons.
The National Nuclear Security Administration says safety is its primary concern and it is working with the board.