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International audience; Cet article retrace l'histoire d'un partenariat qui, par son organisation et sa stratégie, vient d'aboutir à une certification de compétences en IoT dans le cadre de l'Industrie 4.0. Cette 1 ère mondiale pour le réseau de partages "EduNet" a permis d'associer plusieurs acteurs : universitaires chercheurs, étudiants et industriels. Cette certification dite "PLCnext" offre une lisibilité et de réels atouts dans le cadre de la réforme des diplômes universitaires de technologie (Bachelor Universitaire de Technologie) au sein de nos Universités françaises. De nombreux résultats sont présentés en amont de cette certification puisque le partenariat avait débuté dès l'année 2006. Les Qrcodes proposés permettent également aux lecteurs de pouvoir consulter des résultats significatifs. Ce retour sur expérience montre une nouvelle fois, que l'Université doit s'ancrer dans le tissu professionnel pour réussir sa mission éducative. "Une confiance ne se réclame pas, elle se gagne." (Marc Goldstein).

International audience

International audience; In the present work, we have combined spectroscopic and computational methods to elucidate the structures of plutonium(IV) ions with dialkyl monoamide and tetraalkyl-carbamide ligands in the solid state and in solution.

International audience; Effect of irradiation on palladium behaviour in the TBP-alkane-organic phase

International audience; La spectroscopie RMN est une technique capable de fournir des informations structurales sur des complexes métalliques en solution. Elle peut être appliquée à l’analyse de petites molécules en chimie organique, de protéines (macros molécules) en biologie mais aussi en chimie nucléaire avec la nucléarisation des spectromètres [1]. La présence d’un Actinide (An), avec des électrons 5f non appariés, génère une modification du spectre RMN (un élargissement et/ou une variation du déplacement chimique des pics) caractéristique du paramagnétisme du cation.Dans le cas des complexes paramagnétiques de Ln$^{III}$ (éléments 4$f$), le déplacement chimique total $\Delta _{TOT}$ est modélisé par l’équation de Bleaney (équations (a) et (b)) [2]. Il dépend du déplacement chimique paramagnétique induit $\delta _{para}$ qui peut être décomposé en deux contributions : un terme de contact $\delta _{cont}$ (délocalisation de l’électron $f$ sur l’atome donneur du ligand) et un terme dipolaire $\delta _{dip}$ (interaction entre le spin électronique et nucléaire à travers l’espace). A partir de ce dernier terme, on peut déduire des informations structurales en utilisant les constantes de Bleaney.

International audience

International audience; In nuclear fuel reprocessing, the organic ligands in solution are subjected to radiolysis. The resulting effects can lead to modifications of the solution composition which can alter the extraction properties of the ligands, specifically, their extraction efficiency and selectivity. Therefore, it is important to study the effect of radiolysis on the ligands in the organic phase to identify weak points in their molecular structure. This identification can facilitate the design of more stable ligands and of ligands that generate innocuous degradation products. The aim of this work is to increase the understanding of ligand behavior when exposed to ionizing radiation. Specifically, this work aims to characterize the degradation products formed as a result of radiolysis of monoamide extractants involved in plutonium complexes by electrospray ionization mass spectrometry (ESI-MS). ESI-MS is a powerful technique that can be used to identify products through both charge and mass characterization which is especially useful when trying to determine complex formation between degradation products and metal ions. In addition to in-situ alpha irradiation, non-complexed extractants have been irradiated by a gamma source allowing direct comparisons to be made between the type of irradiation and the resulting degradation products that form. To investigate the effect of the structure on the stability of the ligand, in particular the effect of the alkyl group on the carbonyl function, three extractants were chosen, N, N-di-(2-ethylhexyl)butryamide (DEHBA), N, N-di-(2-ethyhexyl)isobutyramide (DEHiBA), and N, N-di-(2-ethylhexyl)-3, 3-methylbutyramide (DEHDMBA).

International audience

International audience; The PUREX process uses 30 percent Vol tri-n-butylphosphate (TBP) diluted in TetraPropylen Hydrogen (TPH, an hydrocarbon diluent) to selectively extract uranium(VI) and plutonium(IV) towards fission products such as ruthenium, molybdene, cesium, palladium, etc. In this process, the solvent is subject to radiolysis, which could result in a modification of the solution composition and the occurrence of cruds. The main consequence of these phenomena is a change in the extraction properties of the solvent, especially in terms of efficiency and selectivity. Many papers report detailed qualitative and quantitative investigations of TBP-TPH degradation due to radiolysis. However, very few data report the influence of the radiolysis on the palladium behaviour. Indeed, some degraded products could interact with palladium to form either complexes or precipitates.In this study, the impact of the radiolytic degradation of TBP-TPH on the palladium behaviour will be thoroughly discussed. For that purpose, a fine characterization of the precipitates formed by et61543;-irradiation of the biphasic system TBP-TPH//Pd-HNO3 will be detailed.

International audience; The PUREX process uses 30%Vol tri-n-butylphosphate (TBP) diluted in TetraPropylen Hydrogen (TPH, an hydrocarbon diluent) to selectively extract uranium and plutonium towards fission products such as ruthenium, molybdene, cesium, palladium, etc. In this process, the solvent is subjected to radiolysis. The resulting effects are a modification of the solution composition and the occurrence of cruds. The main consequence of these phenomena is an alteration of the extraction properties of the solvent, especially in terms of efficiency and selectivity. Many papers report detailed qualitative and quantitative investigations of TBP-TPH degradation due to radiolysis. However, very few data report the influence of the radiolysis on the palladium behaviour. Indeed, some degraded products could interact with palladium to form either complexes or precipitates.In this study, the impact of the radiolytic degradation of TBP-TPH on the palladium behaviour will be thoroughly discussed. For that purpose, a fine characterization of the precipitates formed by et61543;-irradiation of the biphasic system TBP-TPH//Pd-HNO3 will be detailed.

International audience; The radiolytic degradation of di-ethylhexyl-isobutyramide (DEHiBA) was examined by subjecting the compound to gamma irradiation, measuring the remaining concentration of the intact compound, identifying the degradation products and measuring uranium distribution ratios. The combined effects of radiation dose, contact with aqueous solutions of HNO$_3$, and aeration were also examined. The DEHiBA displayed significant stability at doses up to 1000 kGy, undergoing a slow exponential concentration decrease that was accompanied by the appearance of multiple degradation products. The most abundant compounds that were formed by radiolysis resulted from cleavage of the C$_{carbonyl}$-N and C$_{ethylhexyl}$-N bonds, generating di-ethylhexylamine, and mono- ethylhexyl-isobutyramide. Acid contact did alter the radiolytic pathways, with acid favoring cleavage of the C$_{carbonyl}$-N bond, while a more diverse array of compounds were formed in the absence of acid. Pulsed radiolysis experiments were also conducted, in which picosecond bursts of energetic electrons were used to irradiate solutions of dodecane containing DEHiBA; formation of the dodecane radical cation was implicated, which serially reacted with DEHiBA to form radical or radical cation species intermediate in the formation of the observed products. The slow degradation kinetics suggests that DEHiBA possesses good potential for selective extraction of uranium in fuel cycle extraction operations.

National audience

International audience; Molybdenum is an element which is co-extracted with other lanthanides or actinides by many organic solvents in liquid-liquid separation processes. Thus, it is often necessary to manage this element to prevent any pollution of the process output. This paper describes the studies carried out by CEA - DRCP to model and better understand the behavior of molybdenum in the EXAm process. The originality of this liquid-liquid extraction process is the simultaneous presence of two extractants in the organic phase, following two types of mechanisms: extraction by solvation thanks to DMDOHEMA or HDEHP, extraction by ion exchange with HDEHP. Although these two extractants play a specific role for the extraction of lanthanides in each step of the process, with this organic phase only the HDEHP extracts molybdenum, whatever the acidity of the aqueous phase. Unlike lanthanides or americium, speciation of molybdenum in the aqueous phase varies depending on the experimental conditions (pH, concentration of molybdenum). Extraction mechanisms are in principle different for each species. At high acidity, Mo is well simulated by using a Mo(DEHP)2 organic complex. On the other hand, low acidity leads to a more complicated chemistry of molybdenum involving various species in aqueous and organic phases. For this study, over a range of pH greater than 1, it was decided to limit to three species (one cation, one anion and one neutral species): MoO42-, MoO3 and MoO22+. Therefore, the intermediate species, dimers and polymers are initially represented by with one of those three species. Molybdenum is extracted by one of three types of mechanisms, depending on pH value: cation exchange, extraction by solvation or anion exchange. It should be noted that experimentally only the MoO2DEHP2HDEHP2 complex was identified in the organic phase. Experiments were used to determine the values of the constants associated with equilibrium. The model was implemented in the PAREX simulation code to design flowsheets. The calculation results were compared with experimental data from tests carried out in mixer-settlers. The comparison showed the good accuracy of the model. It can be used to predict behavior of the chemical system, including changes in pH associated with the extraction and back-extraction of Mo at low acidity. This modeling can be easily adapted to other separation processes, such as rare earth extraction processes, for which it is necessary to manage molybdenum as an impurity.

International audience; In the framework of the research of a physical model to predict the occurrence of third phase formation in liquid-liquid extraction, we investigate the malonamide extractant used in the so-called DIAMEX process for partitionning of minor actinides from high-level liquid radioactive wastes. Third phase transition was studied from a fundamental point of view. The organisation of the organic phases of the systems malonamides - alkane - water - nitric acid was studied at three levels 1- at a molecular scale by the determination of the compositions of the extracted complexes; 2- at a macroscopic scale by the determination of the phase transition boundaries quantified by the LOC (limit organic concentration) of solutes; 3- at a supramolecular scale by the analysis of the organisation of the species in the organic phases (measurement of the critical micellization concentration, aggregation number and interactions between aggregates). The instability (third phase apparition) has a supramolecular origin attraction between extractant polar cores containing extracted solutes. The alkyl chains of the extractant and the diluent play a symmetrical role towards the physical stability of the organic phase. The phase split of the organic phase results from an increase of the interactions between the malonamide aggregates with the increase of the diluent chain length and the decrease of the extractant chain length. Extractant organic phase behaves as classical AOT reverse micelles and are stabilised with the same rule.

International audience; This paper describes the way adopted to develop DIAMEX-SANEX process. The organic phase contains two extractants : DMDOHEMA extracting actinides(III) from a high nitric acid medium, and the a cationic exchanger for the extraction at lower acidity. Two concepts are studied : in the first one, extractants mixture is used in the whole process, whereas the second route includes a extractant separation step. In that case, only DMDOHEMA is exposed to high-level raffinate and Mo, Zr extraction could be inhibited. In that case, di-alkyl phosphoric acids with 6 carbon atom on branched chains were the more convenient for actinides and extractant separations. They are lipophilic towards aqueous solutions with pH lower than 4, in order to maintained lanthanides in organic phase. They are moreover soluble in basic aqueous solution, so we could recover a organic phase with only DMDOHEMA and TPH. The route without extractant separation used the well known di-(2-ethyl hexyl) phosphoric acid. The main difficulty in that case, is the management of fission products as molybdenum and zirconium, in order to prevent their stripping with actinides(III) and to back extract them before organic phase recycling. The main goal of theses studies is to carry out experiments useful to elaborate a flowsheet for a genuine hot test on a long duration in 2004.