The heat generated by Am-241 poses a challenge in the vitrification of spent mixed oxide (MOX) fuel after reprocessing. When the buffer material temperature exceeds the limit temperature of 100℃ due to the heat generated by vitrified waste, the buffer material quality is degraded, thereby affecting nuclide migration. Therefore, the waste-loading ratio of vitrified waste is estimated by heat generation, which determines the number of glass canisters and repository footprint. An option to reduce heat generation is to blend MOX high-level waste (HLW) with UO₂ HLW. This study evaluated the thermal impact of blending MOX HLW with UO₂ HLW while considering the cooling period and blending ratio. The maximum loading ratio was calculated for each blending condition in the range of buffer material temperatures below 100 °C, and the results were used to estimate the number of glass canisters and assess the repository footprint.

Graphical abstract