Letteratura scientifica selezionata sul tema "MOX (combustibles nucléaires) – Solubilité"
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Articoli di riviste sul tema "MOX (combustibles nucléaires) – Solubilité":
Magnin, Daniel. "Les combustibles MOX et URE à matières nucléaires recyclées". Revue Générale Nucléaire, n. 2 (marzo 1996): 25–27. http://dx.doi.org/10.1051/rgn/19962025.
Crousilles, M., M. Beche e G. Dalverny. "Mesures et système d'informations pour la gestion des matières nucléaires dans l'usine de fabrication de combustibles MOX de COGEMA Cadarache". Revue Générale Nucléaire, n. 1 (gennaio 2001): 37–40. http://dx.doi.org/10.1051/rgn/20011037.
Tesi sul tema "MOX (combustibles nucléaires) – Solubilité":
Thomas, Régis. "MOX dopé chrome : optimisation du dopage et de l’atmosphère de frittage". Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14832/document.
Optimal use of the Mixed Oxide (U,Pu)O2 nuclear fuel in pressurized water reactors is mainly limited by the behavior of gaseous fission produced during irradiation. Within the MOX microstructure, the probability of fission gas release is increased by the presence of rich localized plutonium areas exhibiting a higher local burn-up. A solution consists in optimizing plutonium distribution within the industrial product and promoting the crystalline growth of the fuel grains. For this purpose, addition of chromium sesquioxide during the manufacturing process is currently considered. A previous thesis has shown that the best results are obtained for a Cr addition slightly greater than the solubility limit of Cr in (U,Pu)O2. In order to explain the enhanced plutonium homogeneity, the author highlighted the formation of PuCrO3 precipitates at grain boundaries. A sintering model under reducing atmosphere, with chromium addition, was proposed. However, several points have to be more thoroughly investigated, especially regarding the solubility limit of chromium, as well as the optimal conditions of PuCrO3 precipitates formation. In a first part, speciation of solubilized and precipitated chromium in the mixed oxide (U,Pu)O2 is studied using electron probe microanalysis (EPMA) and X-ray absorption spectroscopy (XAS). It was shown that the oxidation state and the environment of soluble chromium within the (U,Pu)O2 matrix do not depend on the oxygen partial pressure during sintering, neither on the plutonium content of the mixed oxide. However, both chemical nature of the precipitates and chromium solubility depend on the thermodynamic variable and on the plutonium content.Based on these results, a chromium solubility model in the mixed oxide (U,Pu)O2-x was built using the law of mass action governing solubility equilibrium. This model is described as a function of the plutonium content (y) of the solid solution (U1-yPuy)O2-x (y = 0,11 ; 0,275 et 1) and in the oxygen potential range of interest for MOX fuel sintering (-445 kJ/mol < µO2 < -360 kJ/mol). This thermodynamic model contributes to the optimization of the doping stage of fabrication and defines the optimal conditions of PuCrO3 precipitates formation.The aim of the second part is to verify if the thermodynamic conditions of PuCrO3 formation correspond to an optimal plutonium distribution and grain growth of the mixed oxide. Samples manufactured with and without Cr2O3 addition and sintered under various atmospheres were analyzed. It was shown that the U-Pu interdiffusion kinetics is completely modified with chromium addition. Morover, with chromium addition, sintering conditions which increase the U-Pu interdiffusion kinetics, don’t necessarily correspond to optimal grain growth. Based on these results, recommendations for the industrial manufacturing process are proposed. They deal with the choice of the sintering atmosphere and doping concentration to obtain an optimized microstructure
Garzón, Losik Germán Alexander. "Étude et modélisation d’un procédé de dissolution poussée en réacteur continu – application aux oxydes (U, Pu)O₂". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0050.
Plutonium multirecycling aims to stabilise the plutonium inventory and eventually close the fuel cycle in France. This action involves the reprocessing and recycling of plutonium-rich Mixed OXide (MOX) spent fuel, which implies the adaptation of current technologies, in particular dissolution. Therefore, an experimental study of the reaction between uranium-plutonium mixed oxides and nitric acid coupled with chemical reactor modelling is required. In this context, a study of the dissolution of three mixed oxides (30, 40, and 65% Pu/(U+Pu)) and plutonium dioxide in nitric acid is carried out using an optical setup. It can be highlighted that the mixed oxide dissolves according to a similar mechanism as plutonium dioxide when the plutonium content in the solid exceeds 30%. Moreover, only the mixed oxide with the highest uranium content undergoes an autocatalytic reaction mechanism similar to that identified for uranium dioxide. A dissolution model describing the size evolution of a single particle against time was developed. Such model considers the description of particles surface by a fractal geometry approach as well as the surface where the reaction actually takes place. Model was validated by comparison of experimental data from this work and from literature. In addition, a second model was developed, taking into account the single particlemodel, based on population balance equations. The model allows to describe the behaviour of a fluidised bed dissolver, which presents interesting advantages for solid-fluid type reactions. Finally, by implementing the developed model, simulations were performed showing a first estimation of the feasibility of a new dissolution process for current and upcoming MOX fuels
Toury, Grégoire. "Maîtrise de microstructures MOX de type CERCER". Limoges, 2001. http://www.theses.fr/2001LIMO0014.
Since fifteen years, the nuclear fuel MOX, blending of uranium dioxide UO2 and plutonium dioxide PuO2, allow to recycle plutonium derived from the reprocessing of the irradiated fuel UO2. With the aim in view to reach high burnup (70 GWj/t aimed), and particularly to restrain the fission gas release, this work pay particular attention to the realisation of materials with model microstructure
Roussette, Sophie. "Analyse par champs de transformation de matériaux élastoviscoplastiques multiphases : application aux combustibles MOX". Aix-Marseille 2, 2005. http://www.theses.fr/2005AIX22054.
The description of the overall behavior of nonlinear materials with nonlinear dissipative phases requires an infinity of internal variables. An approximate model involving only a finite number of internal variables, Nonuniform Transformation Field Analysis, is obtained by considering a decomposition of these variables on a finite set of nonuniform transformation fields, called plastic modes. The method is initially developed for incompressible elastoviscoplastic materials. Karhunen-Loève expansion is proposed to optimize the plastic modes. Then the method is extended to porous elastoviscoplastic materials. Finally the transformation field analysis, developed by Dvorak, is applied to nuclear fuels MOX. This method enables to make sensitivity studies to determine the role of some microstructural parameters on the fuel behaviour. Moreover the adequacy of the nonuniform method for fuels MOX is shown, the final objective being to be able to apply the model to the MOX in 3D
Oudinet, Ghislain. "Analyse d'images et modélisation 2D/3D de la microstructure du combustible MOX". Saint-Etienne, 2003. http://www.theses.fr/2003STET4011.
The microstructure of the MOX fuel, made with UO2 and PuO2, determines his " in pile " behavior. The french companies CEA and COGEMA are highly interested in its description by image analysis, which is the object of the present work. The segmentation algorithms described here use pictures issued from a microprobe and a SEM, to analyse the plutonium and porosity distribution in the fuel pellets. They are innovating, automated and robust enough to be used with a small data set. They have been successfully tested on different fuels, before and after irradation. Three-dimensional informations have been computed with a genetic algorithm. The obtained 3D object size distributions allowed the modeling of many different industrial and research fuels. 3D reconstruction is accurate and stable, and provides a basis for different studies among which the study of the MOX fuel " in pile " behavior
Bouloré, Antoine. "Etude et modélisation de la densification en pile des oxydes nucléaires UO2 et MOX". Grenoble INPG, 2001. http://www.theses.fr/2001INPG4203.
Amongst the many phenomena which take place in the course of the irradiation of UO2 or (U, Pu)O2 nuclear fuels, one of them involves the elimination of a fraction of the as-fabricated porosity. In-pile densification or sintering can reach 2. 5%, i. E. Approximately half the initial volume of pores is likely to disappear. Our literature survey indicates that the amplitude and kinetics of the phenomenon are both heavily dependent on the initial fuel microstructure. Micro-structural characterisation techniques of oxide fuels have therefore been developed in conjunction with quantitative image analysis methods. The ensuing methodology enables a quantitative comparison of micro-structural features in different fuels and has been applied to ascertaining the influence of the local fission rate and temperature on in-pile densification. It is thus revealed that in-pile operation eliminates a significant fraction of pores smaller than 3 microns in diameter. The experimental data generated has been used to set up a semi-empirical and a mechanistic model. The former is based on experimental results and is not essentially predictive. The inability of this model to predict the in-pile densification of oxide fuels is illustrated by the fact that the maximum fraction of pores that disappears is proportional to an empirical function of fission rate, and temperature. The proportionality factor appears to be difficult to correlate quantitatively to any given micro-structural feature. The model has however been applied to the interpretation of an in-pile densification experiment carried out in the Halden reactor (Norway). The latter model is mechanistic, i. E. It is based on the solution to a set of equations that describe the coupled temperature and radiation induced phenomena which occur in-pile. These can broadly be broken down into three categories : the fission fragment-pore interaction, the creation of point defects as the fission fragments slow down, and the diffusion of these point defects to sinks. The model calculates the evolution of the pore size distribution and has successfully been applied to modelling the in-pile densification behaviour of a fuel pellet characterised before and after irradiation
Mendez, Sandrine. "Etude de l'inerdiffusion U-Pu appliquée au combustible MOX". Aix-Marseille 3, 1995. http://www.theses.fr/1995AIX30036.
Théry, Odile. "Etude de la co-conversion uranium-cérium". Lille 1, 1999. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1999/50376-1999-499.pdf.
Pieragnoli, Adrien. "Influence de l'adjuvant de frittage Cr2O3 sur l'homogénéisation de la répartition en plutonium au sein d'une pastille MOX hétérogène". Limoges, 2007. http://www.theses.fr/2007LIMO4061.
Detalle, Vincent. "Analyse de l'homogénéité du combustible nucléaire MOX par Spectrométrie d'Emission optique sur Plasma Induit par Laser (SEPIL)". Lyon 1, 1999. http://www.theses.fr/1999LYO10267.
Libri sul tema "MOX (combustibles nucléaires) – Solubilité":
IAEA. Safety of Uranium and Plutonium Mixed Oxide Fuel Fabrication Facilities: Specific Safety Guide. International Atomic Energy Agency, 2010.