الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Thorium is an abundant fertile material with reserves about three time’s uranium in the earth’s crust. Isotope Th-232 forms almost 100% of all thorium found and breed to the fissile material U-233. Due to the increased demand on power in general and nuclear power particularly, thorium has to be involved in the nuclear industry. Small and Medium Reactors (SMRs) are the innovative design of nuclear reactors making remarkable interest during recent years. Besides its smaller upfront capital investment compared to normal nuclear reactors, they could be suitable for isolated locations, areas with poor electrical grids or large generating capacities are not required and where the non-electrical products are important. This study investigates thorium utilization as mixed oxide fuel with uranium into Multi-Application Small Light Water Reactor (MASLWR). The code MCNPX has been applied in the fuel pin and the reactor core modeling. Several cases for homogeneous and heterogeneous cores have been studied. Three homogeneous fuels 50%, 70% and 90% ThO2 and the rest UO2 with 4.95% enrichment are studied. Two heterogeneous cases (heterogeneous assembly/ seed and blanket) containing 50% ThO2 and 50% UO2 with 4.95% enrichment are also investigated. Compared to uranium core, all thorium cases have better conversion and shorter cycle length while some cases have less power peaking factor.