Abstract
This study was made for clarification of the pyrohydrolysis behaviors of UF4 and UO2F2. The progress of the reaction was measured by titrating the amount of produced hydrogen fluoride. When nitrogen was used as carrier gas of water, the pyrohydrolysis of UF4 pro-ceeded at the temperatures of 350400°C, and UO2+x (x ?? 0.3) was formed; the value of x decreased with the decrease of oxygen dissolved in the water. In the case of oxygen car-rier gas, the pyrohydrolysis of UF4 formed U3O8-UO2F2 mixture as the reaction product in the above temperature region and the reaction was markedly retarded in the course because of lower rate in the pyrohydrolysis of UO2F2. The pyrohydrolysis of UO2F2 proceeded at a little higher temperature of 450500°C in both cases of nitrogen and oxygen carrier gas and α-UO3 was formed.
