The Radioactive Waste Management Directorate (RWMD) is responsible for implementing
geological disposal of the UK’s higher-activity radioactive wastes. RWMD’s research into
geological disposal considers safety during waste transport to a disposal facility, during
waste disposal operations, and once the facility has been closed. The wastes for disposal
comprise a wide range of materials and include some fissile radionuclides. The presence of
fissile materials requires an assessment of the potential for criticality.

The Monitored Geologic Repository (MGR) Waste Package Operations (WPO) of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Shippingport Pressurized Water Reactor (PWR) (Ref. 1). The Shippingport PWR SNF has been considered for disposal at the proposed Yucca Mountain site.

In February 1996, the Department of Energy (DOE) commissioned a comprehensive effort to document and declassify the United States inventory and other information needed to present a complete picture of the production, acquisition, and utilization of highly enriched uranium (HEU). Highly Enriched Uranium:Striking A Balance presents the results of that study.