SHS of pyrochlore-type ceramic matrices for immobilization of actinide-containing nuclear wastes

Resumo

Mineral-like Y₂(Ti_1–xZr_x)₂O₇ ceramic matrices for immobilization of actinide–Zr–RE-containing high-level nuclear wastes (HLW) were prepared by SHS method. In experiments, HLW were modeled by a mixture of CeO₂, La₂O₃, ZrO₂, MnO₂, and Fe₂O₃ powders. An increase in the HLW content of green mixture decreased the amount of Y₂(Ti_1–xZr_x)₂O₇ in combustion product and increased that of ZrO₂, LaTiO₃, and CaTiO₃; decreased the fractional substitutionality of Zr for Ti; and increased the product porosity. An increase in combustion temperature and suppression of heat sink during SHS reaction did not diminish markedly the porosity of synthesized ceramics.