Purification of U-233 from thorium and iron in the reprocessing of irradiated thorium oxide rods

A two step precipitation using ammonium carbonate and oxalic acid as the pr ecipitants for thorium and iron is developed for the purification of U-233. Ammonium carbonate is added to the feed to increase the pH of the solution . The effect of pH on the solubility of U; Th and Fe in an excess of ammoni um carbonate is studied. This indicates that the solubility of Th and Fe is minimum at pH 7 and the recovery of uranium is maximum. The effect of the concentration of thorium and iron on the recovery of uranium at pH 7 is stu died. This indicates that the ammonium carbonate precipitation tolerates 2 g/l of thorium and 10 g/l of iron keeping losses of uranium to a minimum. I f the feed solution contains more than a tolerable concentration of thorium the precipitation is followed in two steps: (1) Bulk of the thorium is rem oved by oxalate precipitation, (2) the remaining thorium and iron in the su pernatant are removed by ammonium carbonate precipitation. A flow sheet is proposed for the purification of U-233 from thorium and iron present in a s trip product concentrate obtained during the reprocessing of irradiated tho rium rods.