Modeling Minor Actinide Bearing Blanket Fuels for Fast-Neutron Reactors

MABB fuels have been modeled with the MACROS code with specific interest to americium and neptunium transmutation, fuel swelling and effects of self-irradiation on thermal properties. SUPERFACT-1 rod SF6/SF14 consisting originally of (U,Am,Np)O2 pellets was recalculated. Fission gas release, burnup and transmutation behavior as calculated with the MACROS code are in good agreement with the reported PIE data. Disagreement between calculations and observations was revealed for restructuring and central void formation. PIE data show absence of columnar grains and central void, though there are some indications that under operation conditions fuel was close to onset. Due to low thermal conductivity calculated central temperature was higher than 1800°C providing conditions for the central void formation and restructuring. Further analysis of input data and models will be conducted. Also, code calculations were performed to simulate release of fission helium in conditions of MARIOS irradiation.