Comparative Study on 233U and Plutonium Utilization in Molten Salt Reactor

Abstract

A comparative study on ²³³U and Pu utilization in a molten salt reactor (MSR) FUJI-12 has been conducted.
Originally, FUJI-12 uses LiF , BeF2 , ThF4 and ²³³UF4 as fuel. In this study, we have evaluated the use of reactor
grade plutonium and weapon grade plutonium beside ²³³U as the fuel of reactor. The need of ²³³U concentration for
criticality is about 0.34%. In contrast, the demand of the reactor grade plutonium and the weapon grade plutonium
fractions for criticality is around 3.0% and 0.96%, correspondingly. The neutron flux in the thermal energy region
for ²³³U fuel case is higher than in Pu fuel cases due to larger value of the average number of neutrons produced
per neutron absorbed in ²³³U fuel than that of ²³⁹Pu fuel, and may also because of the hardening of the neutron
spectrum owing to plutonium utilization in thermal reactor.