干法转化工艺制备UO2粉末的热力学计算

Thermodynamic Calculations for UO2 Powder Fabrication by a Dry Conversion Process

UO2粉末干法转化工艺是把固体UF。汽化后在反应室中与来自同心喷咀的水蒸汽反应生成中间化合物UO2F2，然后通过螺旋装置输送到回转还原炉（回转炉）中与逆向的Hz-H2O混合气体转化成UOz粉末．本文介绍了从气态UF。到固体UO2粉末在几个不同阶段的主要化学反应热力学，包括UO2F2＋H2O／H2→UO2／UO2和UO2＋HF→UF4，从热力学角度讨论了回转炉第一个温区的温度和气氛（H：O—H2-HF）对UO2被HF氟化成UF4的影响．此外．结合工艺鉴定试验结果，分析和讨论了反应室和回转炉中干法转化工艺参数对UO：粉末物理性能的影响．

A dry conversion process to produce UO2 powder is reported. Uranium fluoride （UF6） is directly hydrolyzed with water vapor from a concentric nozzle to form uranyl fluoride （UO2Fz）, which is transferred to a rotary kiln by a screw and reduced to ceramic-grade uranium dioxide （UO2） powder with backward mixing gases of vapor and hydrogen. Several of the main reactions and thermodynamics calculations for conversion of gaseous UF6 to UO2 powder are reported, including reactions for UO2F2＋H20/H2→＊UO2/UO3 and UO2＋HF→UF4. The influence of the temperature of the first zone and the gas atmosphere of H20-H2-HF on the fluorization of UO2 by HF in term of thermodynamics are also discussed. Moreover, the influences of the dry conversion process parameters on the UO2 physical properties are analyzed by qualification test results.