The Plutonium Uranium Redox EXtraction (PUREX) solvent extraction system is the de facto standard for uranium and plutonium purification in nuclear fuel cycles. The tributyl phosphate (TBP) organic extractant used in PUREX is drives selective uranium and plutonium recovery in this process. While metal recovery by TBP is frequently thought to occur through classical, coordination chemistry extraction mechanisms at lower metal or acid loadings, recent literature has suggest metal recovery under higher metal or acid loadings could occur through more ambiguous mechanisms. The possibilities of reverse micelle formation and percolated networks have been considered, but an alternative possibility of polymerically bridged metal ions might also be responsible for metal ion recovery and complex speciation in TBP-containing organic phases. Molecular dyanamics simulations, NMR diffusion and aggregate interaction experiments, and viscosity studies will be used to consider organic phase speciation and metal ion recovery in PUREX relevant systems. A particular emphasis will be placed on contrasting changes in organic speciation that arise from the extraction of tetravalent (Th4+ and Zr4+) and hexavlent (UO22+) metal ions by TBP.

Organic phase microstructure in TBP-metal-HNO3-H2O systems

254th National Meeting (2017)

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