Study on the kinetics of catalytic hydrogenation of U(VI) in nitric acid solution using a Bubble reactor

In the aqueous reprocessing of spent nuclear fuels by PUREX process, uranium and plutonium are co-extracted by tributyl phosphate leaving the fission products in the raffinate phase. Further, separation of plutonium and uranium from each other is achieved by selectively reducing the plutonium (Pu(IV)) to poorly extractable (Pu (III)) by means of a reducing agent. The objective of this study was to understand the mechanisms of catalytic reduction of U(VI) with hydrogen and hydrazine using 2% Pt catalyst loaded on silica in semi-batch slurry reactor (bubble column reactor).The main objectives were to determine : mechanism of reaction; intrinsic kinetics of hydrogenation of U(VI) using 2% Pt catalyst loaded on silica in semi-batch slurry reactor and; mathematical model for the performance of semibatch reactor under isothermal and atmospheric pressure. Such information will provide the starting basis for further development and optimization of U(VI) catalytic reduction reactor for pilot plant or commercial scale operations