A Neutronic Evaluation of Reprocess Fuel and Depletion Study of VHTR Using MCNPX and WIMSD5 Code

Among the projects of IV generation reactors available nowadays, the (High Temperature Reactors) HTR, are highlighted due to their desirable characteristics and they have been studied by the Instituto Nacional de Ciências e Tecnologia de Reatores Inovadores/CNPq(Brazil). For this work, it evaluated the neutronic behavior and fuel composition during the burnup using the codes (Winfrith Improved Multi-Group Scheme) WIMSD5 and the MCNPX2.6, inserting different percentages of reprocessed fuel in the core. The fuel type “C” coming from Angra-I nuclear power plant, in Brazil, enriched with 3.1% was burnt by three typical cycles and then reprocessed. It recovered (Pu) and minor actinides (MA)being neptunium (Np), americium (Am), curium (Cm), and processed six different fuels varying percentage insertion of reprocessed fuel and enrichment uranium. It analyzed the multiplication factor, temperatures reactivity coefficients, and the composition during the burnup. The results showed, in the analyzed conditions, only one of these fuels is possible to be used. To compare, a reference fuel using 15% enrichment (²³⁵U) was too evaluated.