Nuclear Material: DOE Has Several Potential Options for Dealing with Depleted Uranium Tails, Each of Which Could Benefit the Government

Correspondence issued by the Government Accountability Office with an abstract that begins "Since the 1940s, one mission of the Department of Energy (DOE) and its predecessor agencies has been processing uranium as a source of nuclear material for defense and commercial purposes. A key step in this process is the enrichment of natural uranium, which increases its concentration of uranium-235, the isotope of uranium that undergoes fission to release enormous amounts of energy. Before it can be enriched, natural uranium must be chemically converted into uranium hexafluoride. The enrichment process results in two principal products: (1) enriched uranium hexafluoride, which can be further processed for specific uses, such as nuclear weapons or fuel for nuclear power plants; and (2) leftover "tails" of uranium hexafluoride. These tails are also known as depleted uranium because the material is depleted in uranium-235 compared with natural uranium. Since 1993, uranium enrichment activities at DOE-owned uranium enrichment plants have been performed by the U.S. Enrichment Corporation (USEC), formerly a wholly owned government corporation that was privatized in 1998. However, DOE still maintains approximately 700,000 metric tons of depleted uranium tails in about 63,000 metal cylinders in storage yards at its Paducah, Kentucky, and Portsmouth, Ohio, enrichment plants. It must safely maintain these cylinders because the tails are dangerous to human health and the environment. Uranium hexafluoride is radioactive and forms extremely corrosive and potentially lethal compounds if it contacts water. DOE also maintains large inventories of natural and enriched uranium that are also surplus to the department's needs. Tails have historically been viewed as a waste product because considerable enrichment processing is required to further extract the remaining useful quantities of uranium-235. In the past, low uranium prices meant that these enrichment services would cost more than the relatively small amount of uranium-235 extracted would be worth. However, an approximately tenfold increase in uranium prices--from approximately $21 per kilogram of uranium in the form of uranium hexafluoride in November 2000 to about $200 per kilogram in February 2008--has potentially made it profitable to re-enrich some tails to further extract uranium-235. Even with the current higher uranium prices, however, only DOE's tails with higher concentrations of uranium-235 (at least 0.3 percent) could currently be profitably re-enriched, according to industry officials. About one-third of DOE's tails contain uranium-235 concentrations at that level or higher. In this context, Congress asked us to determine (1) DOE's potential options for beneficially reusing or indefinitely storing its tails, and (2) the potential value of DOE's tails and factors that affect the value.