Diamex Process for Minor Actinide Partitioning: Hydrolytic and Radiolytic Degradations of Malonamide Extractants

Berthon, Laurence; Morel, Jean-Marcel; Zorz, Nicole; Nicol, Christine; Virelizier, H.; Madic, C.

doi:10.1081/ss-100103616

Cited by 79 publications

(44 citation statements)

References 2 publications

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“…There was no evidence for cleavage of the hexylether moiety. These last observations are in contrast to the previous literature (Berthon et al 2001). The mass spectrum of irradiated DMDOHEMA is shown in Figure 2.…”

Section: Alpha Radiolysiscontrasting

confidence: 85%

Radiation chemistry in solvent extraction: FY2010 Research

Mincher¹,

Martin²,

Mezyk³

2010

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This report summarizes work accomplished under the Fuel Cycle Research and Development (FCR&D) program in the area of radiation chemistry during FY 2010. The tasks assigned during FY 2010 included:x Development of techniques to measure free radical reaction kinetics in the organic phase.x Initiation of an alpha-radiolysis programx Initiation of an effort to understand dose rate effects in radiation chemistryx Continued work to characterize TALSPEAK radiation chemistry Progress made on each of these tasks is reported here. Briefly, a method was developed and used to measure the kinetics of the reactions of the •NO 3 radical with solvent extraction ligands in organic solution, and the method to measure •OH radical reactions under the same conditions has been designed. Rate constants for the CMPO and DMDOHEMA reaction with •NO 3 radical in organic solution are reported. Alpha-radiolysis was initiated on samples of DMDOHEMA in alkane solution using He ion beam irradiation and 211 At isotope irradiation. The samples are currently being analyzed for comparison to DMDOHEMA J-irradiations using a custom-developed mass spectrometric method. Results are also reported for the radiolytic generation of nitrous acid, in J-irradiated nitric acid. It is shown that the yield of nitrous acid is unaffected by an order-of-magnitude change in dose rate. Finally, recent results for TALSPEAK radiolysis are reported, summarizing the effects on solvent extraction efficiency due to HDEHP irradiation, and the stable products of lactic acid and DTPA irradiation.In addition, results representing increased scope are presented for the radiation chemistry program. These include an investigation of the effect of metal complexation on radical reaction kinetics using DTPA as an example, and the production of a manuscript reporting the mechanism of Cs-7SB radiolysis. The Cs-7SB work takes advantage of recent results from a current LDRD program to understand the fundamental chemistry of nitration under radiolysis conditions. Finally, work toward understanding the chemistry of irradiated formic acid is presented. This is important because all organic compounds eventually produce formic acid under long-term irradiation.

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Section: Alpha Radiolysiscontrasting

confidence: 85%

Radiation chemistry in solvent extraction: FY2010 Research

Mincher¹,

Martin²,

Mezyk³

2010

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“…DMDOHEMA is sufficiently robust against hydrolysis and radiolysis and, due to the increased lipophilicity, third phase formation is surpressed. [6,7] Several hot demonstration tests using DMDOHEMA are reported in the literature. [8 -10] Recently new diamide like ligands, so called diglycolamides (DGA), with an ether bridge between the two carbonyl groups were discovered by Sasaki et al [11 -13] Amongst the diglycolamides, N,N,N 0 ,N 0 -tetraoctyl diglycolamide (TODGA, Fig.…”

Section: Introductionmentioning

confidence: 99%

Development of a TODGA based Process for Partitioning of Actinides from a PUREX Raffinate Part I: Batch Extraction Optimization Studies and Stability Tests

Modolo

Asp

Schreinemachers

et al. 2007

Solvent Extraction and Ion Exchange

222

136

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The extractant, N,N,N 0 ,N 0 -tetraoctyl diglycolamide (TODGA) has been evaluated for the separation of actinides(III) and lanthanides(III) from a high active raffinate (HAR). The effect of oxalic acid and HEDTA complexant on the extraction of actinides(III), lanthanides(III), and important fission products (e.g. Mo, Pd, Sr, Zr, Ru etc.) from synthetic HAR has been studied with 0.2 mol/L TODGA in TPH.With an extractant mixture of TODGA and tributyl phosphate (TBP) the amount of oxalic acid can be reduced to less than 0.3 mol/L for the effective complexation of zirconium, whereas the distribution ratios of actinides(III) and lanthanides(III) are still high for the separation from HAR. Furthermore the maximum loading of lanthanides (e.g. Nd) can be significantly increased by adding TBP to the extractant. However, the extraction of oxalic acid and nitric acid also increased by the addition of TBP, which can lead to problems during back extraction of the loaded extractant. Extraction studies after radiolysis and hydrolysis reveal that the TODGA þ TBP mixture is a sufficient stable extraction system suited for further process development studies.

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“…This knowledge has been used to advantage in the design of the malonamide dimethyl dioctyl hexylethoxymalonamide (DMDOHEMA) (25), used in the DIAMEX actinide extraction process. In recognition that radiolysis is unavoidable in the irradiated solvent, the ligand molecule was designed with a sacrificial ether linkage situated between its diamide functional groups.…”

Section: Oxidative Reactions Of the • Oh Radicalmentioning

confidence: 99%

An Overview of Selected Radiation Chemical Reactions Affecting Fuel Cycle Solvent Extraction

Mincher

2010

ACS Symposium Series

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Aqueous solvent extraction for the recovery of uranium and plutonium from dissolved nuclear fuel has been used successfully since the advent of the nuclear age. Following decades of PUREX operating experience in several countries, new solvent extraction processes are now being developed worldwide to extract additional long-lived radionuclides , including especially the minor actindes. These must be partitioned from the lanthanides in what is an especially challenging separation. These new processes rely on specialty ligands as metal complexing agents. They must be reasonably stable to hydrolytic and radiolytic degradation in the acidic, irradiated biphasic system. Solvent system degradation may lead to decreases in ligand concentration, production of interfering degradation products, and changes in solvent viscocity and phase separation parameters. Therefore, research is underway in the USA, Europe and Asia with a goal of understanding these affects on solvent extraction efficiency for specific systems. This chapter presents an overview of the important reactions that are common to all solvent extraction systems with reference to recent research findings at Idaho National Lab (INL) and elsewhere. It is shown that indirect radiolysis by reaction with radiolytically produced reactive species such as hydroxyl radical, radical cations and nitrous acid is responsible for much ligand and diluent degradation.

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Diamex Process for Minor Actinide Partitioning: Hydrolytic and Radiolytic Degradations of Malonamide Extractants

Cited by 79 publications

References 2 publications

Radiation chemistry in solvent extraction: FY2010 Research

Radiation chemistry in solvent extraction: FY2010 Research

Development of a TODGA based Process for Partitioning of Actinides from a PUREX Raffinate Part I: Batch Extraction Optimization Studies and Stability Tests

An Overview of Selected Radiation Chemical Reactions Affecting Fuel Cycle Solvent Extraction

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