Effect of the Synthesis Atmosphere on the Process of Formation of Pyrochlore Matrices for HLW Immobilization

Аннотация

The synthesis of ceramic matrices, based on zirconium-enriched pyrochlore for the immobilization of high-level waste (HLW), by means of self-propagating high-temperature synthesis (SHS) under the pressure of argon and compressed air in a SHS-reactor was investigated. The dependences of the phase composition and characteristics of the crystalline phases of the material on the gas pressure were determined. It is shown that all rare-earth elements (REE) (Ce⁴⁺, La³⁺) from the model mixture of the HLW are incorporated into the structure of the ceramic. It is established based on evidence derived from elemental analysis that lanthanides are concentrated in the perovskite and pyrochlore structures.