Heavy metal, esp. actinide oxide dissolution - by treating with nitric acid contg. fluoride in uranyl nitrate melt and dissolving in nitric acid

摘要

Dissolution of hardly soluble heavy metal oxides (I), e.g. PuO2 and ThO2 and mixts. with UO2, is carried out in several stages as follows (a) (I) are introduced into a melt of uranyl nitrate (II) at a temp. of min. 150 deg.C and (b) HNO3 treated with traces of HF is introduced into the melt and vapourised. (c) The vapour is condensed and the distillate returned to the HNO3 reservoir. (d) Pure HNO3 is introduced into the melt and (e) the melt is cooled and dissolved in 1 M HNO3. (f) This soln. is passed to further treatment by familiar conversion processes. The process functions satisfactorily and there is a considerable saving in the time needed for dissolution, allowing increased throughput and a redn. in the fluoride content of the end prod.