Kinetic parameters of a material test research reactor fueled with various low enriched uranium dispersion fuels Original Research Article

The effects of using different low enriched uranium fuels, having same uranium density, on the kinetic parameters of a material test research reactor were studied. For this purpose, the original aluminide fuel (UAlx–Al) containing 4.40 gU/cm3 of an MTR was replaced with silicide (U3Si–Al and U3Si2–Al) and oxide (U3O8–Al) dispersion fuels having the same uranium density as of the original fuel. Simulations were carried out to calculate prompt neutron generation time, effective delayed-neutron fraction, core excess reactivity and neutron flux spectrum. Nuclear reactor analysis codes including WIMS-D4 and CITATION were used to carry out these calculations. It was observed that both the silicide fuels had the same prompt neutron generation time 0.02% more than that of the original aluminide fuel, while the oxide fuel had a prompt neutron generation time 0.05% less than that of the original aluminide fuel. The effective delayed-neutron fraction decreased for all the fuels; the decrease was maximum at 0.06% for U3Si2–Al followed by 0.03% for U3Si–Al, and 0.01% for U3O8–Al fuel. The U3O8–Al fueled reactor gave the maximum ρexcess at BOL which was 21.67% more than the original fuel followed by U3Si–Al which was 2.55% more, while that of U3Si2–Al was 2.50% more than the original UAlx–Al fuel. The neutron flux of all the fuels was more thermalized, than in the original fuel, in the active fuel region of the core. The thermalization was maximum for U3O8–Al followed by U3Si–Al and then U3Si2–Al fuel.