Uranium Sampling & Characterization at the Y-12 National Security Complex

New facilities, changing missions, and a changing regulatory environment have significantly increased the need for sampling and characterization of highly enriched uranium (HEU – uranium enriched to 20% or more 235U) at the U.S. Department of Energy (DOE) National Nuclear Security Administration's (NNSA) Y-12 National Security Complex (Y-12). Y-12 supplies HEU for a wide range of purposes, including materials for refurbished weapons systems; fuel for research reactors around the world; and fuel for naval reactors. Y-12 is also responsible for protecting the nation's inventory of HEU in the newly constructed Highly Enriched Uranium Materials Facility (HEUMF), which includes movement of all qualified materials currently stored in production facilities into HEUMF in preparation for the transition to the Uranium Processing Facility (UPF). Each of these activities faces increasing requirements for detailed understanding of the HEU composition, which can only be met by sampling and characterization. Virtually all United States (U.S.) -origin HEU was made between 1955 and 1965 to supply weapons programs. This HEU was produced from a mix of virgin and reprocessed uranium feed. Since 1965 the U.S. weapons complex has been on total recycle – all HEU used for weapons or reactor programs has come from uranium recovered from earlier products. This long production history has left behind a diverse mix of trace components in U.S. HEU. This information can be used in many ways, but it all begins with proper characterization of materials. Characterization results are analyzed against customer requirements for the purposes of material allocation, material blending, and long-range material planning. Long-range material planning combines characterization results with known historical data to trend HEU supply quality and material blending projections to enable good material stewardship and ensure future requirements are met. Characterization data on materials with a known history is also used to support U.S. nuclear forensics efforts, providing forensic scientists and law enforcement officials with the basic understanding needed to evaluate the origin and process history of interdicted samples. This paper will provide an overview of why and how characterization is used to support Y-12 missions.