Book Description

The thermal decomposition of uranyl fluoride was studied by a thermogravimetric technique between 750 and 880 deg C. The decomposition reaction at atmospheric pressure is 3 UO/sub 2/F/sub 2/ yields 2/3 U/sub 3/O/sub 8/ + UF/ sub 6/ + 1/3 O/sub 2/. In dry helium the rate of reaction was first order with respect to the mass of UO/sub 2/F/sub 2/, with indications that it also was dependent on the gas flow rate. The rate constants, determined with a constant flow rate of dry helium, may be expressed as log k (min/sup -1/) = 11.57--15700/T. In preliminary experiments with dry air and oxygen the rate decreased with increasing oxygen partial pressure; however, data were insufficient for a quantitative relation to be derived. UO/sub 2/F/sub 2/ sublimed, as a parallel first-order proccss, at temperatures above 825 deg C. (auth).