DOE SNF Phase I and II Summary Report

There are more than 250 forms of U.S. Department of Energy (DOE)­owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program (NSNFP) has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. For each fuel group, a fuel type that represents the characteristics of all fuels in that group has been selected for detailed analysis. The DOE SNF will be loaded into the DOE standardized SNF canisters (or multicanister overpacks [MCOs] for N­Reactor SNF), which will be codisposed with five (two for N­Reactor SNF) defense high­level waste glass (DHLW) canisters in a waste package. The results of the analyses performed will be used to develop waste acceptance criteria. The items that are important to criticality control are identified based on the analysis needs and result sensitivities. The analyses have been performed according to Disposal Criticality Analysis Methodology Topical Report (YMP 2003). The methodology includes analyzing the geochemical and environmental processes that can breach the waste package and degrade the waste forms and other internal components, as well as the intact and degraded component criticality analyses. This report also provides the structural, thermal, and shielding analyses of the waste package to ensure that the repository waste acceptance criteria have been met.
The purpose of this report is to summarize eight Phase I and II technical reports that cover the evaluation of codisposal viability of DOE SNF. The evaluations consisted of structural, thermal, shielding, geochemistry, and intact and degraded component criticality analyses. All the analyses performed met the design criteria as defined in DOE and Commercial Waste Package System Description Document (BSC 2003a).