Solvent extraction systems that combine neutral and acidic extractants are being investigated to provide a single process solvent for separating the minor actinide elements from acidic high-level liquid waste, including their separation from the trivalent lanthanides. This approach of combining extractants is referred to as the Actinide-Lanthanide SEParation (ALSEP) process. The process was successfully demonstrated on a lab scale at the Nuclear Engineering Division of Argonne National Laboratory. A simulant of PUREX raffinate containing the major fission products was spiked with 241Am, 244Cm and 147Pm and used as a feed for the ALSEP demo. The process was run using a bank of 1.25-cm centrifugal contactors produced by additive manufacturing. Preliminary results show that the minor actinides were quantitatively recovered from the feed. As a following step, the minor actinides (MA) were completely separated from the lanthanides: less than 0.5 milligram/Liter of total Ln reported in the MA product while no actinides were detected in the Ln product. The only minor drawback of the performed flowsheet was incomplete Mo scrubbing—around 1% of the total Mo was carried out in the organic phase, thus contaminating the MA product at the concentration level of 2 milligram/Liter. This can easily be prevented by adding 2-3 stages to the Mo scrub section. The measured separation factors (SF) for the Pm/MA (worst case scenario) are in the range of 17 to 24, rather close to the equilibrium values. Overall decontamination factors over 1000 were accomplished for the MA/Ln separation

Closing nuclear fuel cycle With ALSEP process: Hot multistage demonstration

255th National Meeting (2018)

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