Towards a new GANEX 2nd cycle process for the co-separation of TRU
Résumé
We report first results on the development of a new system for the GANEX 2 nd cycle: A solvent consisting of N,N,N',N'-tetra-n-octyl-diglycolamide (TODGA) + N,N'-dimethyl-N,N'-dioctyl-2-(2-hexyloxyethyl)malonamide (DMDOHEMA) in kerosene was developed which co-extracts TRU and lanthanides with high distribution ratios and allows for Pu(IV) loading up to 35 g/L. Also the behaviour of non-lanthanide fission products was studied. A substitute for oxalic acid (used as Zr masking agent in DIAMEX processes but not useful in the presence of Pu(IV)) had to be found: CDTA efficiently suppresses the extraction of Zr and also masks Pd which would otherwise be co-extracted. In the selective TRU strip section actinides are back-extracted into an aqueous solution containing a hydrophilic 2,6-bis(1,2,4-triazin-3-yl)pyridine (BTP) and acetohydroxamic acid (AHA) in nitric acid. Lanthanides are kept in the organic phase by a sufficiently high nitric acid concentration; no salting out or buffering agents are required.
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