Searching for incinerating the accumulated plutonium around the world by mixing it with thorium and using this mixture as a nuclear fuel in the CANDU-6

Abstract

This work investigates the possibility of getting rid of the accumulated plutonium around the world by mixing it with fertile materials and using it as a nuclear fuel for CANDU-6. Using plutonium isotopes with thorium as a nuclear fuel for CANDU-6 is a means of preventing the production of other Pu isotopes. MCNPX has been used to design a three dimensional model of the CANDU-6 bundle. Three fuel types including (238U, rgPu)O2, (232Th, rgPu)O2 and (232Th, wgPu)O2 have been examined as nuclear fuel in the designed model and their results were compared with UO2 as a standard fuel. The fuel burnup parameters such as kinf, fissile inventory ratio, plutonium concentration and minor actinides concentration have been analyzed for the suggested fuels. Some of the most related safety parameters such as effective delayed neutrons (βeff), moderator temperature coefficient, coolant temperature coefficient and Doppler constant have been studied. The excess thermal neutrons in the CANDU-6 maximized the benefit of using plutonium-based fuels, where a significant amount of plutonium has been burned during the fuel cycle. From the neutronic and safety point of view, thorium fuel mixed with reactor grade plutonium has proven to be the most promising candidate among the investigated fuels.