Salt Mine Safe for Hot Waste

WASHINGTON--Nuclear weapons waste can safely be stored in a repository carved out of a salt mine in New Mexico, concludes a report released today by the National Academy of Sciences (NAS). The report cautions, however, that additional steps must be taken to prevent radioactive leaks should people many centuries in the future damage what would be a highly radioactive site.

The report evaluated the potential risks to human health and the environment from the Department of Energy's (DOE's) $1.8 billion Waste Isolation Pilot Plant (WIPP), a network of salt caverns near Carlsbad, New Mexico. Completed 8 years ago, WIPP would be the country's first storage site for ``transuranic'' waste, which includes contaminated clothing, machine parts, and other radioactive waste from nuclear weapons sites. But approval to begin using WIPP has been hung up at the Environmental Protection Agency (EPA) for 3 years because critics, including the state of New Mexico, have claimed safety criteria are too lax.

After examining DOE's plans for the site, which is supposed to last at least 10,000 years, an NAS committee found ``no credible or probable scenario for release of radionuclides'' as long as the repository is sealed and left undisturbed. In the event that people purposely or accidentally drill into the site, it should be possible to guard against radioactive releases--for example, by surrounding WIPP with crushed minerals that would trap radionuclides, the report says. ``It is possible to make this repository robust against future intrusions,'' says committee chair Charles Fairhurst, a civil engineer at the University of Minnesota.

DOE says next week it will send EPA its final safety plan for WIPP. George Dials, WIPP's manager, says the remaining issues raised by the academy report ``have all been addressed.'' For instance, he says, DOE has finished an analysis of a worst-case drilling scenario that shows resulting releases still wouldn't exceed strict safety standards. EPA has 1 year to respond to DOE's safety plan.