Advancement of Nuclide Separation Using Ion-Exchange Methods in the Processing of Radioactive Wastes

Abstract

The advancement of nuclide separation in the processing of high level liquid wastes (HLLWs) was reviewed. Selective separation and recovery of useful radioactive nuclides (Cs, Pd and Am) containing in HLLWs are of importance in relation to the partitioning and their effective utilization. The granular composites of AMP (ammonium molybdophosphate) immobilized with porous alumina or calcium alginate exhibited a high selectivity towards Cs, and the mutual separation of Cs/Rb was performed through the packed column. The fine crystals of insoluble ferrocyanides (KNiFC and KCuFC) were granulated by microencapsulation with polymer gels of alginates and had a high selectivity towards Pd. The extractants (Cyanex 301, Cyanex 302) were also encapsulated in the matrices of alginates and alginic acid. The microcapsule of Cyanex 302-CaALG had a relatively large separation factor of Pd/Ru and Pd/Rh, and Pd ions were effectively separated from Ru and Rh. The Cyanex 301-HALG microcapsule with a high affinity for Am was effective for the chromatographic separation of Am/Eu. The microencapsulation methods for the granulation of fine inorganic ion-exchanges and extractants are thus expected for the advanced nuclide separation in the nuclear fuel cycle and environmental remediation.