Investigation of batch-tray calcination-reduction of ammonium diuranate to uranium dioxide

Abstract

Process cycles have been developed on the half-kilogram scale for the conversion of ADU to UO2 powder of specified surface area in the range 3-10 m2/g. The recommended cycle involves calcination of ADU in nitrogen during heating to the reduction temperature, followed by reaction with 30 volume per cent hydrogen in nitrogen and stabilisation at ambient temperature with 2 volume per cent oxygen in nitrogen. UO2 surface area increased from 3 to 10 m2/g as the reduction temperature changed from 700 to 500°C, but was not sensitive to the surface area of the precursor ADU or the hydrogen flow rate.