Analysis of thorium and transuranium utilization in a small modular reactor

Abstract

This study presents neutronic analyses of a small modular reactor utilizing transuranium and thorium. Two different fuel cases are considered in the analyses as the transuranium extracted from PWR-MOX spent fuel (a form of a mixture of minor actinide and Pu isotopes) (Case A) and 4.5 % enriched UO2 with ThO2 (the form of separate fuel rods) (Case B). The total power of the considered small modular reactor containing 69 assemblies is 450 MW thermal. In both fuel cases, the time-dependent critical burnup calculations are carried out by using MCNPX 2.7 code until their effective neutron multiplication factors decrease to 0.99. The calculations bring out that the small modular reactor can operate for quite a long time without refueling and that a new fuel with a richness of 1.05 % can be obtained from ThO2 as well as energy production.