Legacy of actinides in the weapons complex

Highly enriched uranium (HEU) and plutonium are the actinides of major concern in the legacy materials of the United States weapons complex. The HEU can be mixed with normal and depleted uranium to produce reactor-fuel uranium unsuitable for weapons use. Restoration of this mixture to weapon grade requires isotopic enrichment of the uranium. By contrast, plutonium can be converted to weapons-grade material by relatively simple chemical separations. This paper describes the plans being considered for disposition of the plutonium and presents a brief review of the amounts and types of transuranium (TRU) residues in various sites in the United States. Processing and removing of these residues are at different stages at different sites, and ultimate remediation and release of the various sites present an extremely complex problem, as some sites will require long-term monitoring and restricted use. Some current approaches to these problems are reviewed.