The chemistry of fuel reprocessing: Present practices, future trends

Campbell, D.O.; Burch, William

doi:10.1007/bf02039470

Cited by 23 publications

(7 citation statements)

References 6 publications

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“…One of the most industrially relevant metal extractants is tributyl phosphate (TBP), a neutral solvating extractant used to separate plutonium and uranium from used nuclear fuel in the plutonium–uranium redox extraction (PUREX) process. − The structure of TBP is shown in Figure . TBP has a density close to that of water and is usually dissolved in kerosene, an inert hydrocarbon diluent, to facilitate disengagement of the organic phase .…”

Section: Introductionmentioning

confidence: 99%

Tributyl Phosphate Aggregation in the Presence of Metals: An Assessment Using Diffusion NMR Spectroscopy

et al. 2016

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Diffusion nuclear magnetic resonance (NMR) spectroscopy was used to find the interaggregate interactions and sizes of tributyl phosphate (TBP) aggregates containing varying concentrations of uranium or zirconium and HNO in an n-dodecane diluent. The average diffusion coefficients of TBP species were measured using a pulsed-field gradient stimulated echo experiment with a longitudinal eddy-current delay (STE-LED). Interaggregate interactions were determined by measuring the diffusion coefficient of TBP in a sample after a series of dilutions with n-dodecane. The interaction-independent infinite dilution diffusion coefficient was also calculated from these measurements. The sizes of TBP aggregates were calculated from the infinite dilution diffusion coefficient using the Wilke-Chang equation. Interactions between TBP aggregates were observed to correspond to a hard sphere potential with a repulsive component. Aggregate sizes found by NMR were comparable to literature values found using small-angle neutron scattering. The diffusion of TBP in heavy organic third phases indicates that the third phase may be a bicontinuous structure like that found in traditional surfactant systems.

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Section: Introductionmentioning

confidence: 99%

Tributyl Phosphate Aggregation in the Presence of Metals: An Assessment Using Diffusion NMR Spectroscopy

et al. 2016

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“…Here, the overbar indicates an organic phase species. The extracted nitrate anions serve to charge neutralize the complex. − …”

Section: Introductionmentioning

confidence: 99%

A Molecular Dynamics Study of Tributyl Phosphate and Diamyl Amyl Phosphonate Self-Aggregation in Dodecane and Octane

Servis

Tormey

et al. 2016

J. Phys. Chem. B

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A molecular dynamics model for tributyl phosphate (TBP) and diamyl amyl phosphonate (DAAP) is presented using the Generalized AMBER Force Field (GAFF) and the AM1-BCC method for calculated atomic charges with a modification to the phosphorus-containing dihedral parameters. The density and average molecular dipole in a neat liquid simulation, and dimerization in dodecane and octane diluents, compare favorably to experimental values. At low extractant concentration, investigation of the dimer structure reveals the offset "head-to-head" orientation as the predominant structure over a range of TBP and DAAP concentrations with a phosphoryl oxygen separation distance between dimerized extractants of 3-5.5 Å. At high extractant concentrations, a graph analysis of extractant aggregates was used to determine concentrations of each aggregate size and the average coordination number, which gives a measure of the linearity of the aggregates. For aggregates up to 7 extractant molecules, the mean free energy of association per molecule was found to be 0.55-0.59 and 0.72 kcal/mol for TBP and DAAP, respectively. In both diluents, TBP formed large aggregates more frequently than DAAP, and those aggregates were more nonlinear than their DAAP equivalents. This finding anticipates differences in aggregation chemistry between TBP and DAAP in PUREX extraction systems.

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“…Reprocessing of irradiated nuclear fuels intended at the recovery of fissile material involves the dissolution of fuel in nitric acid to get a clear solution containing U, Pu, fission products, and a residue containing the metallic and oxide forms of some of the fission products and the separation is carried out using the Purex process [81]. The studies on the composition and dissolution characteristics of high burn-up fuels and the probable consequences on the fuel reprocessing are reported [82,83].…”

Section: Applications In Nuclear Industrymentioning

confidence: 99%

Mass Spectrometry: A Boon to Nuclear Industry

Ramkumar¹

2014

J Anal Bioanal Tech

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What is Mass Spectrometry?Mass spectrometry is analytical instrument which has been used for more than a century with its initial work on mass charge ratio being carried out by W. Wien, J.J. Thomson, and other physicists [1]. Mass Spectroscopy is an analytical laboratory technique to separate the components of a sample by their mass. The sample is vaporized into a gas and then ionized. The ions are then accelerated through a potential difference and focused into a beam. The ion beam passes through a magnetic field which bends the charged stream. Lighter components or components with more ionic charge will deflect in the field more than heavier or less charged components. A detector counts the number of ions at different deflections and the data can be plotted as a 'spectrum' of different masses. Therefore it is clear that mass spectrometer performs a simple measurement that of mass. The earlier work in the measurement of mass had led to the discovery of isotopes and it was in the 1930s that these measurements were correlated to the chemical structures and therefore were used extensively for biological applications for the characterization of natural products. Further progress in the field of mass spectrometry including isotopic labeling methods, hyphenated techniques and softer ionization methods made it an ideal tool for the analysis of macromolecules [2]. With the various fields that employ mass spectrometry growing in number, nuclear industry is also an important area wherein applications of mass spectrometry exist. Chronological Development in Mass spectrometryThe earliest mass spectrometry was in 1897 with the discovery of electrons made by J.J.Thomson. Around 1919, the observation studies of isotopes using mass spectrometry were carried out by F.W. Aston created a mass spectrometer in which ions were dispersed by mass and focused by velocity. This design improved the mass spectrometer resolving power by an order of magnitude compared to that achieved by AbstractMass spectrometry is a versatile technique that is used for the determination of elements at the trace and ultratrace level along with the isotope ratios. The accuracy in the quantification of isotope ratios of radionuclides is essential for environmental monitoring, migration studies, dating, determination of burn-up of fuel, nuclear material accounting and radioactive waste control. Inductively coupled plasma mass spectrometry (ICP-MS) is advantageous due to its outstanding sensitivity, precision and good accuracy for isotope ratio measurements and enhanced figures of merit for the determination of isotope ratio measurements. These advantages can be enhanced by various other variations of ICP-MS like the use of a multiple ion collector device (MC-ICP-MS). The review gives an idea of the various applications in the nuclear field and touches upon some of the important elements used in nuclear industry.

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The chemistry of fuel reprocessing: Present practices, future trends

Cited by 23 publications

References 6 publications

Tributyl Phosphate Aggregation in the Presence of Metals: An Assessment Using Diffusion NMR Spectroscopy

Tributyl Phosphate Aggregation in the Presence of Metals: An Assessment Using Diffusion NMR Spectroscopy

A Molecular Dynamics Study of Tributyl Phosphate and Diamyl Amyl Phosphonate Self-Aggregation in Dodecane and Octane

Mass Spectrometry: A Boon to Nuclear Industry

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