Computational Study of 19.75% UO2 Fuel for the Core Conversion of Nigeria Research Reactor-1 (NIRR-1) from HEU to LEU

SCALE 6.1 code system and VENTURE-PC code system has been used for the core conversion of Miniature Neutron Source Reactor (MNSR) from Highly Enriched Uranium (HEU) system (90.2% enriched UAl4 fuel) to Low Enriched Uranium (LEU) system (19.75% enriched UO2-zircaloy-4 fuel). All other structure materials and dimensions of HEU and LEU cores are the same except the increase in the fuel cell diameters for the proposed LEU core. Results obtained show that the peak power density of 4.310033 Watts/cc, maximum neutron density of 6.94535e-6 n/cc, total control rod worth of pcm, clean cold core excess reactivity of pcm, of , shutdown margin of pcm and neutron flux profile of for the potential LEU core are slightly greater than those of the current HEU core. These results also indicate that the LEU core can operate perfectly in natural convection mode which shows the accuracy of the model and precision of the transport code system used.