Immobilization of Th(IV) in Yttrium Stabilized Zirconia Ceramics

Safe disposal of nuclear waste requires matrix materials with strong resistance against corrosion and dissolution over a period of more than 10E6 years. Zirconium based ceramics might be used as storage material, because their natural analogues zircon, ZrSiO4, and zirconia, ZrO2, are known to remain stable in geological cycles up to approximately 2·10E9 years. We intend to investigate the structural substitution of thorium in Y-stabilized ZrO2 ceramics. Th(IV) is selected for this study because it represents the typical oxidation state IV which appear in Pu, U and Th containing nuclear waste. The aim of this study is to determine to what extend Th(IV) can be introduced into zirconium ceramics without Zr/Th phase separation.