Actinides and depleted uranium as an alternative for sustainable nuclear energy in thermal reactors

Spent fuel reprocessing can be an alternative to address the environmental and social challenges associated with nuclear energy. This study investigates the use of depleted uranium, stored at the beginning of the cycle, in the spiking with the reprocessed fuel, eliminating the need for mining new fuel or thorium for spiking. Additionally, the radiotoxicity of burned recycled nuclear fuels is analyzed, and their composition is compared with that of thorium and depleted uranium, demonstrating that the use of both results in similar radiotoxicity characteristics. The work also reinforces the use of methods GANEX and UREX + due to the efficiency of proliferation risks compared to PUREX. The results show that the amount of spent fuel in a cycle and the depleted uranium stored in the beginning of the cycle are sufficient to constitute a reprocessed fuel to be inserted in the reactor. There is no big difference between the material required for the proliferative resistance methods and PUREX. The DU-spiked reprocessed fuels behave more similarly to standard UOx regarding radiotoxicity and decay heat, whereas Th-spiked fuels exhibit higher long-term radiological impact due to U-233 production. Depleted uranium in reprocessing offers environmental and waste management advantages, while proliferation resistant methods such as GANEX and UREX + enhance safety and societal acceptance.