UO_2凝胶球陈化洗涤干燥工艺研究

Aging, Washing and Drying Processes of UO_2 Gelled Spheres

通过加入预陈化过程、控制陈化时的升温速率,使凝胶球内外完全胶凝且均匀一致;通过洗涤时去离子水温度及洗涤次数的控制,避免小球开裂,减少废液量;通过干燥时真空度与温度的调节,避免小球开裂,均匀干燥。采用重络酸钾滴定的方法测量了陈化液中NO3-浓度随陈化时间的变化,进而判定陈化结束的时间;测量了洗液中NO3-浓度,进而判定洗涤过程是否结束。采用该陈化洗涤干燥工艺顺利完成了多批次的验证试验,最终制备出了满足设计要求的UO2核芯。所采用的陈化洗涤干燥3个工艺步骤在一台设备中顺序完成,适用于大批量UO2凝胶球(～3kgU/批次)的制备,可用于规模化的生产。

The aging, washing and drying processes are in sequence accomplished in one device which is suitable for the batched preparation of UO2 gelled spheres (～3 kgU/batch), and also can be used in large-scale production. The inside and outside gelation of gelled spheres are complete and uniform through pre-aging process and heating rate controlling. Temperature of deionized water and frequency of lavation are controlled in washing to avoid cracking and decrease liquid waste. The vacuum degree and temperature in drying process have been adjusted to avoid cracking and make drying uniformly. The NO3 - content variation with time in aging solution and the content in washing solution have been measured by potassium dichromate titrimetric analysis, and then the processes whether finished to be determined. Batches of verification test are smooth-going using the AWD process, and the UO2 kernels satisfied design requirements have been prepared finally.