溶胶-凝胶法制备二氧化铀核芯的U_3O_8欠酸溶解工艺

U_3O_8 Acid-Deficient Dissolution Process for Preparation of UO_2 Kernels by Sol-Gel Method

在UO2核芯的制备工艺中,为获得高浓度铀的硝酸铀酰溶液,同时降低溶液中硝酸根含量,即获得低于硝酸铀酰标准化学计量比(硝酸铀酰中硝酸根与铀酰离子化学计量比为2)的溶液,必须采用欠酸溶解工艺。本文采用分批加料和阶段性加热方式获得了很好的溶解效果,得到的硝酸铀酰溶液中U含量为2.1～2.5mol/L,NO3-和U的摩尔浓度比为1.6～1.8,溶液pH大于1.4,从而成功制备出合格的欠酸溶解的硝酸铀酰溶液。在此基础上,根据多次溶解试验的结果总结出了溶液密度与U含量的经验公式。

Uranyl nitrate solution with high uranium concentration and hypostoichiometric c(NO3-)/c(U) ratio (the stoichiometric ratio of c(NO3-)/c(U) is 2 in standard uranyl nitrate solution) is crucial for preparation of qualified UO2 kernels for high temperature gas-cooled reactor. An acid-deficient dissolution process was developed for the preparation of uranyl nitrate solution. In the process the raw materials U3O8 was added stepwise and the heating for the process was controlled in stages. Uranyl nitrate solutions with c(U)=2.1-2.5 mol/L, c(NO3-)/c(U)=1.6-1.8 and pH>1.4 could be prepared. A relationship between solution density and uranium concentration was summarized.