Kinetics extraction of uranium(vi) and plutonium(iv)by n,n-dialkylamides using different experimental techniques

International audienceMass transfer coefficients of uranium(VI) and plutonium(IV) between nitric acid and a monoamide-based solvent upon extraction were determined to support the development of a liquid-liquid extraction process for the multirecycling of plutonium from the future spent nuclear fuels. The kinetics data were obtained by using three different techniques the single drop technique, the Nitsch cell and the rotating membrane cell (RMC). Beyond the comparison of the influence on the kinetics of the different technics, the main objective of this study was to determine whether the transfer is controlled by diffusion or chemistry. The results obtained by the single drop technique showed that U(VI) and Pu(IV) mass transfer constants are quite similar for the extraction step. The global results point out that the resistance to the transfer is essentially located in the organic phase and the diffusion process would mainly control the kinetics

Determination of U(VI) and Pu(IV) mass transfer constants with N,N-dialkylamides in liquid-liquid extraction

International audienceIn the frame of the development of Generation IV reactors, CEA is developing a new liquid-liquid extraction process for the multirecycling of plutonium from the future spent nuclear fuels. Thermodynamic data have already been acquired for the modelling of the extraction equilibriums in this process, however, a full phenomenological model requires kinetic data too. Thus, this paper summarizes the acquisition of mass transfer coefficients of uranium(VI) and plutonium(IV) between nitric acid and a monoamide-based solvent upon extraction with three different techniques using a constant interfacial area the single drop technique. They are compared to results obtained with Nitsch cell and rotating membrane cell (RMC) methods.The influence of temperature, nitric acidity, viscosity of the organic phase and, in the case of the moving drop technique, the drop size and the nature of the continuous phase (aqueous or organic) on the mass transfer coefficient of uranium and plutonium during the extraction step was studied

Monoamide vs TBP A comparative study of uranium and plutonium mass transfer in solvent extraction

International audienceFor many years, N,N-dialkylamides have been identified as interesting extractants for the reprocessing of spent nuclear fuels [1-2]. To develop an advanced solvent extraction process for plutonium multi-recycling from Generation IV reactors, many equilibrium data have been collected. However little is known on the mass transfer kinetics. Indeed, the knowledge of the mass transfer coefficients and the understanding of the implied phenomena are essential to simulate the process in contactors with short residence time and for its scale-up in industrial contactors.To supplement kinetic data related to a process using a mixture of DEHBA-DEHiBA as extractant, mass transfer coefficients of uranium(VI) and plutonium(IV) between nitric acid and the monoamide based solvent have been acquired using the Single drop method [3].This experimental technique based on a 1.5 meters height column allows the determination of global mass-transfer coefficients Kg (m.s-1) for cations of interest. It involves the formation of single drops of one phase rising or falling through the continuous phase. The variation of the element (U or Pu) concentration in the drop is measured in the feed and in the raffinate for different travel times.The influence of temperature, solute concentration, interfacial area (drop size), viscosity of the organic phase and emulsion nature (continuous aqueous or organic phase) on the kinetics of uranium and plutonium extraction has been studied. The results have been exploited to determine either the chemistry or the diffusion process controls the kinetic.These data are compared with results obtained in similar conditions with TBP solvent currently used in the PUREX process in order to estimate the difference of kinetics between these two solvents

Microfluidique et cinétique de transfert application à un procédé d'extraction liquide-liquide d'actinides

International audienceL’outil microfluidique pour étudier le transfert de matière présente une alternative aux méthodesclassiques de cinétique de transfert, en permettant un contrôle plus fin de l’hydrodynamique et uneréduction des distances de diffusion, tout en réduisant les volumes mis en jeu grâce à la réductiond’échelle. Le système de référence uranium(VI) - HNO$_3$ 3 M / TBP (30%) - TPH a été utilisé pourles expériences de mesure de cinétique de transfert de matière en microfluidique.Un des verrous de l’exploitation des résultats en expériences de mesure de cinétique de transfertest la connaissance de la géométrie de l’interface liquide-liquide sur la profondeur du micro-canalet dans le sens de l’écoulement

High velocity flows as a tool to determine the kinetics constant of uranium(VI) extraction

International audienc

Development of a high velocities co-flowing stratified microfluidic process to obtained kinetic constants for liquid-liquid extraction

International audiencePresentation des resultats d'extraction L-L de l'U(VI) par le TBP en microfluidique developpement du dispositif de mesure et validation des hypotheses experimentales, explication des travaux de modelisation pour calculer les cinetiques de transfert chimique ou diffusionnelle

Modélisation Simplifiée de Liaisons Collées à l’Aide de la Technique par Macro-Element. Revue des Développements Réalisés depuis 2004

National audienceno abstrac

Microfluidique et cinétique de transfert application à un procédé d'extraction liquide-liquide d'actinides

International audienceL’outil microfluidique pour étudier le transfert de matière présente une alternative aux méthodesclassiques de cinétique de transfert, en permettant un contrôle plus fin de l’hydrodynamique et uneréduction des distances de diffusion, tout en réduisant les volumes mis en jeu grâce à la réductiond’échelle. Le système de référence uranium(VI) - HNO$_3$ 3 M / TBP (30%) - TPH a été utilisé pourles expériences de mesure de cinétique de transfert de matière en microfluidique.Un des verrous de l’exploitation des résultats en expériences de mesure de cinétique de transfertest la connaissance de la géométrie de l’interface liquide-liquide sur la profondeur du micro-canalet dans le sens de l’écoulement