Power density effect on feasibility of water cooled thorium breeder reactor

Breeding is made possible by the high value of neutron regeneration ratio η for ²³³U in thermal energy region. The reactor is fueled by ²³³U–Th oxide and it has used the light water as moderator. Some characteristics such as spectrum, η value, criticality, breeding performance and number density are evaluated. Several power densities are evaluated in order to analyze its effect to the breeding performance. The η value of fissile ²³³U obtains higher value than 2 which may satisfy the breeding capability especially for thermal reactor for all investigated MFR. The increasing enrichment and decreasing conversion ratio are more significant for MFR < 0.3. The required enrichment and conversion ratio do not change significantly caused by power density change for very tight lattice cell (MFR < 0.3), however, its strongly depends on the power density change for higher MFR (MFR ≥ 0.3). Breeding condition of all investigated power densities can be achieved for burnup ≥ 30 GW d/t at MFR = 0.3 and it requires about 3.5% of required ²³³U enrichment. Number density of ²³³Pa decreases significantly with decreasing power density which leads the reactor has better breeding performance because lower capture rate of ²³³Pa.