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.

核废料的安全处置要求基体材料在10^6年以上的时长内具备优异的抗腐蚀与抗溶解性能。锆基陶瓷（zirconium based ceramics）可被用作核废料储存材料，因其天然类似物锆石（zircon, ZrSiO₄）与氧化锆（zirconia, ZrO₂）已被证实可在地质循环中稳定存续约2×10^9年。本研究拟探究钍在钇稳定氧化锆陶瓷（Y-stabilized ZrO₂ ceramics）中的结构取代行为。选取四价钍（Th(IV)）作为研究对象，是由于其代表了含钚（Pu）、铀（U）与钍的核废料中典型的+4价氧化态。本研究的目标为明确四价钍可在何种程度内掺入锆基陶瓷中，且不会发生锆/钍的相分离（phase separation）。