Potential immobilization of Cs and Sr within perovskite-type CsSr2Ta3O10 ceramic waste forms

The removal of Cs and Sr from high level radioactive waste is very important for ecological protection. However, simultaneous immobilization of Cs and Sr is rarely reported. In this work, a perovskite structure CsSr 2 Ta 3 O 10 was synthesized by molten salt method. CsSr 2 Ta 3 O 10 has good thermal stability up to 900 °C at least. Under the γ irradiation of Co-60, most of the material maintained its structural integrity. CsSr 2 Ta 3 O 10 demonstrates a wide range of pH durability, where Cs is stable in the pH range from 4 to 12 and Sr from 2 to 12. Its frame structure remains stable in the pH range from 2 to 12 and will not be decomposed. Further sintering of CsSr 2 Ta 3 O 10 ceramic waste forms results in a high density of 93% − 95%. Moreover, leaching experiments conclude that the long-term leaching rates of Cs and Sr begin to stabilize after 14 days, reaching the order of 10 0 and 10 −3 g·m −2 ·d −1 . These results provide a possibility for the simultaneous immobilization of Cs and Sr.