Self-protection analysis of denatured thorium-plutonium fuel

Abstract

With growing demands for commercial nuclear power, there is also a growing need for better energy efficiency from nuclear power reactors. In order to reach a high burnup up to 100 MWd/kg, previous research has examined the use of thorium-plutonium mixedoxide fuel as a potential candidate for this high-burnup goal. Though the neutronics studies have looked upon this fuel type favorably, the purpose of this paper is to investigate the self-protection capabilities of this fuel type, for anti-proliferation purposes. In particular, there were two proliferation-resistance methods that were analyzed. First, this study examined the time-dependant dose-rate of the spent fuel caused by the decay of the isotope uranium-232, which releases a high-energy gamma of 2.6 MeV. Next, this study examined the possibility of denaturing the fuel with depleted uranium in order to dilute the weapons-usable isotope uranium-233 in the spent fuel. The U-232 dose rate was also calculated for the denatured case. Ultimately, the study found that there was a negligible different in the amount of time that it takes for either fuel type to become self-protective. The denatured case showed that it requires much more plutonium than the undenatured case in order to ensure that there is not sufficient weapons-usable U-233 in the discharged fuel.