Evaluation of Codisposal Viability for MOX (FFTF) DOE-Owned Fuel

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. Fast Flux Test Facility (FFTF) fuel has been designated as the representative fuel for the mixed-oxide (MOX) fuel group which is a mixture of uranium and plutonium oxides. Demonstration that other fuels in this group are bound by the FFTF analysis remains for the future before acceptance of these fuel forms. The results of the analyses performed will be us1~d to develop waste acceptance criteria. The items thatareimportanttosafetyareidentifiedbas1edontheinformationprovidedbyNSNFP. Prior to acceptance of fuel from the MOX fuel group for disposal, the items important to safety for the fuel types that are being considered for disposal under the MOX fuel group must be demonstrated to satisfy the conditions determined in this report.
The analyses have been performed by following the disposal criticality analysis methodology, which was documented in the topical report submitted to U.S. Nuclear Regulatory Commission (YMP/TR-004Q, Disposal Criticality Analysis Methodology Topical Report). The methodology includes analyzing the geochemical and physical processes that can breach the waste package and degrade the waste forms and other internal components, as well as the structural, thermal, and shielding analyses, and intact and degraded criticality. Addenda to the topical report will be required to establish the critical limit for DOE SNF once sufficient critical benchmarks are identified and performed.