The Nuclear Regulatory Commission assured Rep. Jim Matheson and other Congress members it will stay true to its commitment to see that depleted uranium can be disposed of safely in Utah and elsewhere.
But the agency doesn't detail how it reached its decision to stick to its 1981 system, which treats depleted uranium as "Class A" waste, the standard category for the least hazardous low-level waste.
Matheson, of Utah, and Rep. Ed Markey, D-Mass., hope to find at least some of those answers in the thousands of pages of documents that they have requested from NRC and that are due next Monday.
Markey, the chairman of the House energy and environment subcommittee, likened the NRC's handling of depleted uranium to giving a "C" student an "A" grade before the final exam, only in this case the consequences are much more serious and enduring.
"When the NRC's normal process is subverted," Markey said in a news release, "it creates confusion and doubt and reduces the trust that the American people have in their regulator."
But, in his April 9 letter, NRC Chairman Dale Klein noted regulators will look closely at the disposal of large quantities of "DU," as it's commonly called, before uranium enrichment facilities begin to need disposal in 2011.
"The Commission ... is first and foremost committed to ensuring DU will be disposed of in a manner that protects public health and safety," concludes a memo attached to Klein's letter.
Last month the congressmen demanded more information about the agency's March 18 decision on depleted uranium. They want to know more about why the agency is continuing to use a category that some have described as a loophole that could potentially allow too-dangerous waste to be permanently buried in low-level waste sites, like EnergySolutions Inc.'s specialized landfill in Tooele County.
Depleted uranium, the radioactive material left over from nuclear fuel enrichment and old government stockpiles, is unusual for low-level waste because it actually gets hotter over time. The hazard increases, the NRC says, "until after 1 million years" because of the increasing concentration of radioactive decay products and their increasing mobility.
Regulators said they plan two further reviews to make sure that more than 11 tons can be disposed of safely in one place. One is revamping radioactive waste classification system to focus on the risks posed by various forms of waste.
The other is a standard for site-specific reviews that would, in effect, help regulators decide how suitable Utah and other locales would be for large volumes of depleted uranium.
The total U.S. waste stream of depleted uranium is about 1.4 million tons, roughly half from government stockpiles and half from anticipated uranium enrichment.
"Class A waste was meant to be the lowest classification -- one that poses the least threat to health and safety," said Matheson. "Any decision regarding depleted uranium disposal that raises concerns in that regard is not acceptable to me."
Jill Sigal, spokeswoman for EnergySolutions, said the company already has done a site-specific review for depleted uranium and has been disposing it since 1990.
"We safely dispose of Class A material," she said. "Class A material includes depleted uranium. ... We will comply with all regulations."
Dane Finerfrock, director of the state's Radiation Control Division, said the upcoming reviews were important to make sure there is no doubt that sites like EnergySolutions would keep the waste safe over the long run. "It's a great opportunity for some things to get worked out" from a technical standpoint, he said.