Chemical Separation of Actinides from High Level Radioactive Liquid Waste Using Diglycol-amide (DGA) Compounds

An innovative chemical separation process for the treatment of high level radioactive liquid waste (HLW) has been developed in our laboratory. There are two main stages in this process, the stage for our task is to recover all actinide (An) ions together with lanthanides (Ln), another task is to separate TRU from Ln. The diglycol-amide (DGA) compounds employed in this stage have several advantages, (1) carbon, hydrogen, oxygen and nitrogen atoms in their structures and gasification by combustion, (2) easy synthesis, (3) neutral and tridentate ligands, and (4) strong extraction ability with An from HNO{sub 3}. DGA compounds with the different structures can be obtained by attachment of the different alkyl groups to amidic N atoms, i.e., N,N,N',N'-tetra-octyl-diglycol-amide (TODGA), N,N,N',N'-tetra-dodecyl-diglycol-amide (TDdDGA), N,N,N',N'-tetra-methyl-diglycol-amide (TMDGA) and N,N,N',N'-tetra-ethyl-di-glycol-amide (TEDGA). TODGA and TDdDGA can be dissolved in hydrocarbon diluents, on the other hand, TMDGA and TEDGA are water-soluble ligands. TODGA and TDdDGA are expected to use as an extractant and TMDGA and TEDGA can be used for the reverse-extraction of An. The utility of DGA compounds, which shows the different characters, is revealed and the flow-sheet based on the salt-free concept is exhibited in this paper. (authors)