Review: Solvent Systems Combining Neutral and Acidic Extractants for Separating Trivalent Lanthanides from the Transuranic Elements

Summary. The selective partitioning (P) of long-lived minor actinides from highly active waste solutions and their transmutation (T) to short-lived or stable isotopes by nuclear reactions will reduce the long-term hazard of the high-level waste and significantly shorten the time needed to ensure their safe confinement in a repository. The present paper summarizes the on-going research activities at Forschungszentrum Jülich (FZJ), Karlsruher Institut für Technologie (KIT) and Institute for Transuranium Elements (ITU) in the field of actinide partitioning using innovative solvent extraction processes. European research over the last few decades, i.e. in the NEWPART, PARTNEW and EUROPART programmes, has resulted in the development of multi-cycle processes for minor actinide partitioning. These multi-cycle processes are based on the co-separation of trivalent actinides and lanthanides (e.g. by the DIAMEX process), followed by the subsequent actinide(III)/lanthanide(III) group separation in the SANEX process. The current direction of research for the development of innovative processes within the recent European ACSEPT project is discussed additionally. This paper is focused on the development of flow-sheets for recovery of americium and curium from highly active waste solutions. The flow-sheets are verified by demonstration processes, in centrifugal contactors, using synthetic or genuine fuel solutions. The feasibility of the processes is also discussed.

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“…A distinction is made between two process variants, described in detail in recent reviews [1,[7][8][9].…”

Section: Introductionmentioning

confidence: 99%

A review of the demonstration of innovative solvent extraction processes for the recovery of trivalent minor actinides from PUREX raffinate

et al. 2012

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“…In view of this, the current method is a two-cycle approach (16). In contrast, several authors have attempted to develop a single-cycle method for the separation of trivalent actinides from HLLW (17)(18)(19)(20)(21)(22)(23)(24). There are two approaches generally followed in the single-cycle method.…”

Section: Introductionmentioning

confidence: 94%

“…The first approach involves the separation of trivalent actinides directly from HLLW using a complex mixture of solvent phase (17). In the second approach, the actinides and lanthanides are separated from HLLW using a combination of neutral and acidic extractants (19)(20)(21)(22)(23)(24)(25). This is followed by selective stripping of actinides alone from the organic phase.…”

Section: Introductionmentioning

confidence: 99%

Studies on the Radiochemical Degradation of Tetraethylhexyl Diglycolamide and Ethylhexylphosphoric Acid inn-Dodecane Solution

Nayak

Chaurasia

Kumaresan

et al. 2014

Separation Science and Technology

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The organic solvent phase composed of N,N,N',N'-tetra-2-ethylhexyl diglycolamide (TEHDGA) and bis(2-ethylhexyl)phosphoric acid (HDEHP) in n-dodecane (n-DD) is regarded as a promising candidate for single-cycle separation of americium (III) from high-level liquid waste. The radiochemical degradation of a solution of TEHDGA + HDEHP/n-DD was investigated by irradiating the solvent to various absorbed dose levels of γ-radiation. The neat extractants or a solution of extractants in n-dodecane were irradiated in the presence and absence of nitric acid. The degree of degradation was assessed by measuring the variation in the extraction behavior of Am(III), Eu(III) and other metal ions in irradiated solvent systems. The distribution ratio of americium and europium decreased with increase of absorbed dose. The presence of n-dodecane enhanced the radiolytic degradation of the solvent; however, the role of nitric acid during degradation was insignificant. The recovery of Am(III) and Eu(III) from the irradiated solvent system was studied. The recovery of Am(III) was quantitative in 3 contacts; however, the separation factor of Eu(III) over Am(III) during stripping decreased marginally with increase of absorbed dose.

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“…This work was subsequently followed up by work aimed at synthesizing chelating diamide ligands specifically designed for rare earth chelation by controlling the dihedral angle between the two carbonyl groups through the use of a rigid backbone [44]. Ultimately, this led to the development of rigid bicyclic diamides, tailored for the solvent extraction of rare earth cations [41,48,49]. This precedent demonstrates that an aprotic chelating diamide ligand should have good affinity for lanthanide cations.…”

Section: Introductionmentioning

confidence: 97%

“…Chelating diamides have been recognized for a number of years as being affective ligands for solvent extraction of lanthanides and actinides [41][42][43][44][45][46][47][48][49]. Tetraalkyl malonamides and succinamides have been studied in [42,43,[45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Design and synthesis of chelating diamide sorbents for the separation of lanthanides

Fryxell

Chouyyok

Rutledge

2011

Inorganic Chemistry Communications

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Review: Solvent Systems Combining Neutral and Acidic Extractants for Separating Trivalent Lanthanides from the Transuranic Elements

Cited by 113 publications

References 31 publications

A review of the demonstration of innovative solvent extraction processes for the recovery of trivalent minor actinides from PUREX raffinate

A review of the demonstration of innovative solvent extraction processes for the recovery of trivalent minor actinides from PUREX raffinate

Studies on the Radiochemical Degradation of Tetraethylhexyl Diglycolamide and Ethylhexylphosphoric Acid inn-Dodecane Solution

Design and synthesis of chelating diamide sorbents for the separation of lanthanides

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