The U.S. Department of Energy's Office of Science and Technology has issued Depleted Uranium: A DOE Management Challenge, a 15-page report summarizing three years of studies evaluating options for long-term management of depleted uranium. Depleted uranium, produced during the nuclear fuel cycle as a by-product of enrichment, is only .7 percent as radioactive as uranium-235 but is still radioactive enough to be the subject of DOE and Nuclear Regulatory Commission regulations. According to the report, DOE has 555,000 metric tons of depleted uranium hexafluoride stored in 50,000 cylinders throughout the DOE complex. The annual storage and maintenance costs reach approximately $10 million.
Because depleted uranium is more acceptable to regulators when it is used as a product than when it is stored, the report recommends that depleted uranium be used for shielding in containers for spent nuclear fuel or vitrified high-level waste. As a result of the studies summarized in the report, DOE's Office of Nuclear Energy identified concrete shielding using depleted uranium as its aggregate as the best possible way to recycle the material in the DOE inventory. Although substantial, the cost of recycling the depleted uranium in a concrete-based shielding in containers is comparable to or less than the cost of disposing of the depleted uranium as a radioactive waste. The report considers the cost and feasibility of several depleted uranium storage cask designs.
