Separation of Am and Cm from HLLW by extraction chromatography using novel R-BTP extraction resins

Wei, Y.*; Hoshi, Harutaka; Morita, Yasuji  ; Bruggeman, A.*; Goethals, P.*

To separate the long-lived minor actinides (MA = Am, Cm) from high level liquid waste (HLLW), we have been studying an advanced process by extraction chromatography which uses minimal organic solvent and compact equipment. Generally, the process consists of two separation columns packed with CMPO extraction resin for elemental group separation and R-BTP extraction resin for the isolation of MA from lanthanides (Ln), respectively. R-BTP is a family of nitrogen-donor ligand which has been verified to have stronger adsorption affinity for trivalent MA over Ln(III). As an extractant or adsorbent, it is generally considered that R-BTP compounds shall be used in a weakly acid medium, since the compounds show less stability in acidic medium due to the protonation of nitrogen atoms. However, we have found that the adsorption selectivity for Am(III) and Cm(III) and chemical stability of R-BTP adsorbents strongly depend on the length and structure of the alkyl group.