Depleted Uranium Hexafluoride Conversion Operations

Depleted uranium hexafluoride (DUF6) is a byproduct of uranium enrichment at Department of Energy gaseous diffusion plants since World War II. Uranium enrichment, a process used to make fuel for nuclear power plants and for military applications, created a legacy of approximately 800,000 metric tons of DUF6 that was stored in about 67,000 steel cylinders at the Department’s gaseous diffusion plant sites Public Law 107-206, signed by the President in August 2002, requires that no later than 30 days after enactment, the Department must award a contract for the design, construction, and operation of DUF6 conversion facilities at the Paducah, Kentucky, and Portsmouth, Ohio, sites. Public Law 107-206 also stipulates that the contract require groundbreaking for construction to occur no later than July 31, 2004, at both sites. We initiated this audit to determine the Department’s progress in converting its DUF6 inventory.We found that the Department made limited progress in converting its DUF6 inventory into a more stable form for reuse, storage, or disposal. After encountering numerous problems with safely converting the DUF6 inventory, the Department revised its baseline in 2019 and estimated that it would then take an additional 18 years, until 2054, to convert the inventory. The Department revised its projected costs to convert the full inventory of DUF6 to around $11.7 billion, more than two and a half times its original estimate of $4.6 billion.In addition to COVID-19 impacts, delays in converting the DUF6 occurred, in part, due to inherent technical or mechanical flaws that resulted in numerous shutdowns of the plants. While the Department invested in plant modifications to address some of these flaws, it had not completed comprehensive studies of the plants’ inherent flaws and their realistic conversion capabilities.Management concurred with our finding and one recommendation, and its proposed corrective actions are consistent with our recommendation.