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International audience; This paper focuses on data reconciliation (DR) applied to the nuclear fuel treatment PUREX process. Data reconciliation improves the degree of confidence in available information and generates consistent data. The inventory and analysis of the plant data (position and type of sensors, flowsheet diagrams ) allow to represent the observability and the redundancy of the process using graph theory methods. The aggregation of the graph is a compulsory step due to the need in redundant measures. When many bias are present in the data, the redundancy is decreasing. This can lead to a loss of information and maybe the incapacity to apply DR. The proposed methodology combines DR and simulation to locate and estimate multiple biases and to make data consistent in the case of many disrupted hard sensors measuring connected flows.

International audience; For the design of purification cycles using liquid-liquid extraction techniques, a process development approach based on process modelling was chosen. This approach involved the development of a qualified simulation tool, which had been successfully used for process flowsheet design of industrial plants, and safety analysis of plant operation. Possible software applications to aid plant operation using this qualified simulation code were proposed, including automatic flowsheet calculations; simulation tools for process monitoring or control; and a diagnostic tool. This third application allows detection of the occurrence of a process malfunction from data obtained in monitoring the state of process parameters. A combination of calculations, using the process simulation code and neural network techniques, is used to determine the nature of the malfunction (i.e. which operating parameter has changed), the amplitude of the parameter change, and the time at which the malfunction has occurred. Such a diagnostic application is possible because of the reliability and speed of the process simulation. The tool's ability, following detection of a malfunction, to identify the changes in operating parameter responsible for the malfunction using an appropriate process monitoring treatment could be an example of a feature of interest for NRTA purposes. This paper will present the process simulation tool and the diagnostic tool, to illustrate what could be achieved using existing qualified simulation tools. There are still further developments required, but the application is considered worthy of further consideration.

International audience; Le traitement du combustible irradié est réalisé à l’aide du procédé PUREX. Aprèsdissolution des pastilles de combustible, les éléments d’intérêt sont séparés puis purifiés en vue deleur recyclage. Le code PAREX, développé par le CEA, simule l’évolution des paramètres duprocédé au cours du temps et a aidé à la conception des ateliers de purification de l’usine de LaHague.L’objet de la thèse est d’estimer en temps réel un ensemble de paramètres caractérisantl’état du procédé grâce à l’exploitation des mesures disponibles sur l’installation, et plusparticulièrement celles représentatives de l’état du procédé nommés indicateurs d’état. Dans lecas des opérations d’extraction-lavage, la charge en uranium et plutonium du solvant est unfacteur déterminant : elle doit être suffisamment élevée pour obtenir une bonne décontamination,sans être excessive afin d’éviter d’altérer le rendement de récupération des cations d’intérêt. Lasimulation du procédé à l’aide du code qualifié PAREX, permet de relier les paramètresopératoires (débits et caractéristiques des solutions d’entrée, etc) aux différentes mesures de suivireflétant l’état du procédé et d’accéder précisément aux paramètres d’état recherché. L’objectif dela thèse est ainsi de bâtir un algorithme réalisant l’estimation des indicateurs d’état du procédé etde vérifier leur cohérence.Pour construire l’outil, deux étapes majeures se distinguent :- la réconciliation des données de l’installation afin de consolider et rendre cohérent l’ensemble dujeu de données;- l’optimisation de ces données d’entrée pour la bonne estimation des indicateurs d’état grâce aucode PAREX.

International audience; In the frame of the development of Generation IV reactors, CEA is developing an advanced liquidliquid extraction process for the multirecycling of plutonium from the spent nuclear fuels. Thermodynamic data have already been acquired for the modeling of the extraction equilibriums in this process, but accurate kinetic data are also required to simulate the process in short-time contactors and for its scale-up in industrial contactors such as pulsed columns. 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: the single drop technique, the Nitsch cell and the rotating membrane cell (RMC). The influence of temperature, nitric acidity, viscosity of the organic phase, the drop size and the nature of the continuous phase (aqueous or organic) on the transfer of uranium and plutonium during the extraction step was studied. The results obtained by the single drop technique showed that U(VI) and Pu(IV) mass transfer constants are quite similar. These data were compared with the literature as with results obtained in similar conditions with the TBP solvent currently used in the PUREX process. They revealed that the kinetics of U(VI) extraction with this monoamide solvent is about three times slower than with TBP, probably because of the higher viscosity of the monoamide-based solvent. The single drop method allowed the most complete study but the other methods brought some qualitative information to better understand the phenomena involved in the transfer of uranium and plutonium with this system. 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. An attempt to estimate the chemical and the diffusionnal kinetic constants based on experimental results led also to the same conclusion. These results lead to a better understanding of this extraction system and will help to simulate experimental profiles of uranium and plutonium concentrations measured in continuous tests performed in mixer-settlers or pulsed columns with this monoamide solvent.

International audience; In the frame of the development of Generation IV reactors, CEA is developing an advanced liquidliquid extraction process for the multirecycling of plutonium from the spent nuclear fuels. Thermodynamic data have already been acquired for the modeling of the extraction equilibriums in this process, but accurate kinetic data are also required to simulate the process in short-time contactors and for its scale-up in industrial contactors such as pulsed columns. 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: the single drop technique, the Nitsch cell and the rotating membrane cell (RMC). The influence of temperature, nitric acidity, viscosity of the organic phase, the drop size and the nature of the continuous phase (aqueous or organic) on the transfer of uranium and plutonium during the extraction step was studied. The results obtained by the single drop technique showed that U(VI) and Pu(IV) mass transfer constants are quite similar. These data were compared with the literature as with results obtained in similar conditions with the TBP solvent currently used in the PUREX process. They revealed that the kinetics of U(VI) extraction with this monoamide solvent is about three times slower than with TBP, probably because of the higher viscosity of the monoamide-based solvent. The single drop method allowed the most complete study but the other methods brought some qualitative information to better understand the phenomena involved in the transfer of uranium and plutonium with this system. 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. An attempt to estimate the chemical and the diffusionnal kinetic constants based on experimental results led also to the same conclusion. These results lead to a better understanding of this extraction system and will help to simulate experimental profiles of uranium and plutonium concentrations measured in continuous tests performed in mixer-settlers or pulsed columns with this monoamide solvent.

International audience; Process development approach adopted in CEA, based on modelling studies, includes the determination of mass transfer efficiency of the contactors used to perform the different process operations. For monoamide based solvents, tests of several process operations as uranium extraction and back extraction, nitric acid stripping from a uranium loaded solvent were performed in laboratory scale pulsed columns of different heights. The recorded concentration profiles of the species of interest (uranium, nitric acid, ..) were simulated using the PAREX code. Mass transfer kinetics of the species of interest realized with that extractant system permit a very good simulation of the concentration profiles. These results will permit to give the ground data to design the process operation in industrial scale contactors, and will be a guide for further development to enhance if necessary the transfer efficiency of the contactor.

International audience

International audience; The PAREX code has been widely used for process designused for the flowsheet design of the purification cycles ofthe La Hague plant build for nuclear fuel treatment. Thispaper focused on the use of the code as an aid for plantoperation through two application examples. The first oneis related to on site flow sheet available marginevaluation of the extraction zone of a first cycle flowsheet. The second example concern the plutoniumstripping operation of a plutonium cycle, where the codehas been used to explain the shift of plutonium leak in thesolvent outlet observed.