Progress towards the development of a new GANEX process

摘要

We report first results on the development of a new system for a GANEX 2nd cycle developed by the "ACSEPT" project. A solvent system consisting of 0.2 M N,N,N',N'-tetra-n-octyl-diglycolamide (TODGA) + 0.5 M N,N'-dimethyl-N,N'-dioctyl-2- (2-hexyloxyethyl)malonamide (DMDOHEMA) in kerosene was formulated which co-extracts TRU elements and lanthanides with high distribution ratios and allows for Pu(IV) loading up to ~40 g?L-1 at 3 M HNO_3. Neptunium redox chemistry and extraction in the TODGA/DMDOHEMA phase has been studied in order to identify optimum conditions for Np extraction. Further, the behaviour of non-lanthanide fission products was investigated to identify a substitute for oxalic acid (used as a Zr masking agent in DIAMEX processes where there is no Pu in the feed). 1,2-cyclohexanediaminetetraacetic acid (CDTA) efficiently suppresses the extraction of Zr and also masks Pd which would otherwise be co-extracted.