High capacity immobilization of U₃O₈ in Gd₂Zr₂O₇ ceramics via appropriate occupation designs

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• 作者：Xirui Lu^a ; ^{luxiruimvp116@163.com} ; Chenxi Hou^a ; Yi Xie^a ; Xiaoyan Shu^a ; Yi Ding^a ; Dengsheng Ma^a ; Wei Ren^b ; ^c ; Liang Bian^b ; ^c
• 关键词：High-level radioactive waste ; Immobilization ; Pyrochlore ; Occupation ; Phase evolution
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：43
• 期：3
• 页码：3015-3024
• 全文大小：2745 K
• 卷排序：43

文摘

An optimal occupation of U4+ and U6+ in Gd2Zr2O7 is necessary for a really high immobilization capacity of U3O8 in Gd2Zr2O7 based waste forms. Based on four kinds of occupation methods, a series of U3O8-doped Gd2Zr2O7 compositions have been synthesized. The effects of U3O8 content on the phase and microstructure evolution of Gd2Zr2O7 pyrochlore waste forms were investigated. Detailed XRD analysis show that the four sets of samples exhibit a single defect fluorite structure within the range of 0<x≤0.4, 0<x≤0.66, 0<x≤0.6 and 0<x≤1, respectively. The highest solubility of U3O8 is about 82.29 wt% when the occupation design (U4+ and U6+ substitute for Gd and Zr, respectively) was employed. It was found that the cell parameters of compounds in Set A (Gd2–3x(U4+xU6+2x)Zr2O7+7x/2) decrease with increasing x, while those of the other compositions increase. Moreover, the uranium are almost homogeneously distributed in all samples.