Plutonium Loading of Prospective Grouped Actinide Extraction (GANEX) Solvent Systems based on Diglycolamide Extractants

Abstract

The Grouped Actinide Extraction (GANEX) process is being developed for actinide recycling within future nuclear fuel cycles. Interactions between potential solvents and macro-concentrations of plutonium are one of the most important issues in defining the GANEX process. Surprisingly, plutonium loading of diglycolamide (DGA) based solvents such as tetra-octyl DGA (TODGA) causes precipitation rather than a conventional third phase, in direct contrast to results with U(VI), Th(IV) or lanthanide ions. Various DGA based solvent systems have been screened for their plutonium loading capacity and 0.2 M TODGA with 0.5 M DMDOHEMA in a kerosene diluent is selected as the optimum solvent formulation of those tested. Plutonium can be relatively easily stripped from this solvent using aqueous acetohydroxamic acid but this is very acid dependent in the low acidity region.

Keywords:

• Plutonium
• thorium
• third phase
• precipitation
• diglycolamide
• GANEX
• acetohydroxamic acid

ACKNOWLEDGMENTS

Financial support for this work from Sellafield Ltd., the UK Nuclear Decommissioning Authority, and European Framework Project “ACSEPT” (FP7-CP-2007-211 267) is gratefully acknowledged. Aritz Durana and Javier de Mendoza (ICIQ, Spain) are thanked for provision of TODGA and other ligands and Clément Hill (CEA, France) for an initial sample of DMDOHEMA. The NNL authors wish to dedicate this article to the memory of their colleague, Dr. Ivan Owens (NNL, Materials and Products), in recognition of his support and encouragement.

Notes

*G. Modolo, Forschungszentrum Jülich, in-house synthesis.

^†Ionic nitrate is D_3h and not local C_2v symmetry but it is added to the table for comparison.

Figure 4 IR-ATR spectrum of the isolated solid compared to the original solvent (0.2 M TODGA/0.5 M TBP in OK diluent).