Effect of Specific Power on Fuel Reactivity and Costs in Thorium-Fueled Reactors

In reactors fueled with thorium, increasing specific power leads to reduction of fuel reactivity lifetime and conversion ratio because of the appreciable decay time and neutron absorption cross section of Pa²³³. A generalized study of these effects in thorium-U²³³ fueled reactors has been carried out using a simplified reactor model. It was found that the most important specific power effect on fuel reactivity is the holdup of Pa²³³, rather than its burnout to U²³⁴. Using conventional cost bases, the effect of specific power on the fuel costs for thorium fueled reactors has been shown to be small in the range of practical specific powers.