Studies on the dissolution behaviour of ThO2 and (U,Th)O2 by a solid state reaction method

Abstract

Summary A simple and fast method for the dissolution of sintered ThO2 and (U,Th)O2 was developed. The products formed when these oxides were fused with ammonium sulphate at various temperatures were found to be readily soluble in dilute nitric acid. Among all the products obtained at various temperatures, (NH4)2 Th (SO4)3 and (NH4)2(Ux,Th1-x)(SO4)3, obtained at 365 °C, were found highly soluble (>99%). After dissolution thorium was separated selectively by oxalate precipitation method. More than 95% of uranium was recovered from the solution by ammonium diuranate precipitation method. The products formed at different temperatures were characterised by X-ray, thermal and chemical analysis techniques.