The Dept. of Energy¿s Office of Environ. Mgmt. (EM) is responsible for one of the world¿s largest cleanup programs: treatment and disposal of radioactive and hazardous waste created as a by-product of nuclear weapons production and energy research at sites across the country, such as EM¿s Hanford Site in Wash. State and the Savannah River Site in S. Carolina. Computer models (CM) -- which represent physical and bio-geochemical processes as math formulas -- are one tool EM uses in the cleanups. This report: (1) describes how EM uses CM in cleanup decisions; (2) evaluates how EM ensures the quality of its CM; and (3) assesses EM¿s overall strategy for managing its CM. This is a print on demand report.

DOE Tank Waste: How clean is clean enough? The U.S. Congress asked the National Academies to evaluate the Department of Energy's (DOE's) plans for cleaning up defense-related radioactive wastes stored in underground tanks at three sites: the Hanford Site in Washington State, the Savannah River Site in South Carolina, and the Idaho National Laboratory. DOE plans to remove the waste from the tanks, separate out high-level radioactive waste to be shipped to an off-site geological repository, and dispose of the remaining lower-activity waste onsite. The report concludes that DOE's overall plan is workable, but some important challenges must be overcomeâ€"including the removal of residual waste from some tanks, especially at Hanford and Savannah River. The report recommends that DOE pursue a more risk-informed, consistent, participatory, and transparent for making decisions about how much waste to retrieve from tanks and how much to dispose of onsite. The report offers several other detailed recommendations to improve the technical soundness of DOE's tank cleanup plans.