Effect of Preparation Process on Structure and Property of Uranium Pyrochlore-based Glass-ceramics Waste From

In view of the deficiencies of the lanthanide nuclides tend to remain in the glass matrix in the glass-ceramics waste form, based on the traditional fusion-heat treatment glass-ceramics preparation process, the process was appropriately improved, and the effect of process variation on the phase structure of the glass-ceramics solidified body was studied. The structural properties of various waste forms were characterized by XRD, FT-IR, SEM-EDS, ICP-MS and other analytical methods. The experimental results show that the GC1 obtained by the traditional method (process A) mainly consists of anorthite (CaAl₂Si₂O₈) and calcium uranium oxide (CaUO₄) as the main phase. When the pre-sintering (process B) or ball milling (process C) treatment is added, the growth of the CaUO₄ phase in the sample is inhibited, and the precipitation of uranium pyrochlore slightly increases. When pre-sintering and ball milling techniques are combined (process D), CaAl₂Si₂O₈ and CaUO₄ in GC4 are suppressed, a large amount of tetragonal uranium pyrochlore phase is precipitated, and the phase is basically consistent with the composition of the precipitated phase originally designed. The solid solution of U in a site of pyrochlore is as high as 0.75. After the sample is leached in deionized water for 14 d, the surface of the glass substrate is slightly dissolved, and the ceramic phase does not change significantly during the leaching.