Development of a New Flowsheet for Co-Separating the Transuranic Actinides: The "Euro-GANEX" Process

A flowsheet for a novel GANEX (Grouped ActiNide EXtraction) process has been tested in a spiked flowsheet trial in a 32 stage plutonium-active centrifugal contactor rig with a simulant feed that contained 10 g/L plutonium as well as some fission products and other transuranic actinides. The solvent system used was a combination of 0.2 mol/L N,N,N’,N’-tetraoctyl diglycolamide (TODGA) and 0.5 mol/L N,N‘-(dimethyl-N,N‘-dioctylhexylethoxy-malonamide (DMDOHEMA) in a kerosene diluent that co-extracted actinides and lanthanides. Actinides were subsequently selectively co-stripped away from the lanthanides using a sulphonated and, therefore, hydrophilic bis-triazinyl pyridine (BTP) complexant in conjunction with acetohydroxamic acid (AHA). Plutonium and americium recoveries were high with decontamination factors across the strip contactors of ~14,000 and ~390 respectively. However, approximately 30 % of neptunium was lost to the aqueous raffinate which was due to a large recycle within the first extract-scrub section. Some recycle of strontium was also observed but in this case it was fully directed to the raffinate stream. In the stripping section, a small fraction of europium (taken as a model lanthanide ion), ca. 7 %, was found in the actinide product stream. Modelling of selected data using the PAREX code has shown that, even with a relatively simplistic treatment, reasonable agreement between modelling and experiment can be obtained; giving confidence in the use of modelling to refine the GANEX flowsheet design prior to further testing with irradiated fast reactor fuel.JRC.E.5-Nuclear chemistr