Demonstration of a TODGA-based continuous counter-current extraction process for the partitioning of actinides from a simulated PUREX raffinate, part II: Centrifugal contactor runs

The efficiency of the partitioning of trivalent actinides from a PUREX raffinate is demonstrated with a TODGA+TBP extractant mixture dissolved in an industrial aliphatic solvent TPH. Based on the results of cold and hot batch extraction studies and with the aid of computer code calculations, a continuous counter-current process is developed and two flowsheets are tested using miniature centrifugal contactors. The feed solution used is a synthetic PUREX raffinate, spiked with (241)Am, (244)Cm, (252)Cf, (152)Eu, and (134)Cs. More than 99.9% of the trivalent actinides and lanthanides are extracted and back-extracted and very high decontamination factors are obtained for most fission products. The co-extraction of zirconium, molybdenum, and palladium is prevented using oxalic acid and HEDTA. However, 10% of ruthenium is extracted and only 3% is back-extracted using diluted nitric acid. The experimental steady-state concentration profiles of important solutes are determined and compared with model calculations and good agreement is generally obtained.