Investigation on transformation of gaseous fluorides into oxides

The process of high-temperature uranium hexafluoride reduction hydrolysis with water vapour and hydrogen mixture was investigated. The investigated process was based on the one-stage method of obtained grain uranium dioxide by building it up in the course of uranium hexafluoride pyrohydrolysis transformation into uranium dioxide on its nucleus particles, which at the same time are the boiling bed material. Investigated were the pyrohydrolysis temperature regime, the influence of the component correlation (UF6, H2O, H2) on the reaction mechanism, the reaction solid products defluorination kinetics. The optimum parameters of the pyrohydrolysis process (the temperature, the component correlation, the fluidization regime) were determined. Obtained were the uranium dioxide grains with the bulk weight of 5.9-6.5g/cm3, pycnometric density of 10.3-10.6 g/cm3, and the fluorine content of less than 0.01%. The grain size ranges from 50 μm up to 1000 μm. The investigations proved that the obtained product is applicable for reactor fuel preparation by vibration-packing method