Group separation of trivalent minor actinides and lanthanides by TODGA extraction chromatography for radioactive waste management

Abstract

For the development of an advanced reprocessing process, it is one of the most important tasks to separate long-lived minor actinides (MA). The authors have been developing an advanced reprocessing process, ERIX process, including a selective separation of MA(III) [Proceedings of the JAERI-Conference 2002–2004 (2002) 225]. In this work, group separation of trivalent MA and lanthanides (Ln) from simulated high level liquid waste (HLLW) using a novel silica-based extraction resin containing the newly developed chelating extractant was investigated. N, N, N′, N′-Tetraoctyl-3-oxapentane-1,5-diamide (TODGA) was developed recently and has high affinity for MA(III) and Ln(III) in concentrated nitric acid medium [Solv. Extr. Ion Exch. 20 (2002) 687]. The novel silica-based extraction resin was prepared by impregnating TODGA into a macroreticular styrene–divinylbenzene copolymer which is immobilized in porous silica particles with a mean diameter of 50 μm. This impregnated resin has the good properties such as fast kinetics and less swelling for use in extraction chromatography. The results of separation experiments for the simulated HLLW solutions using TODGA extraction resin demonstrated that both MA(III) and Ln(III) can be effectively isolated from almost all of the other FP elements.