Academic literature on the topic 'Défauts de radiation'
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Journal articles on the topic "Défauts de radiation":
Laé, Jean-François. "Le clapotis des mots gracieux." Sociologie et sociétés 40, no. 2 (March 10, 2009): 109–29. http://dx.doi.org/10.7202/000649ar.
Administrateur- JAIM, MOULION TAPOUH Jean Roger, BITJONG NDOMBOL Grégory, OUOGUE TEINGUENG Francisse Xavier, DONGMO FOMEKONG Sylviane, SAMBA Odette Ngano, and MOIFO Boniface. "Evaluation of entrance surface dose and justification of pediatrics chest radiography in three university-affiliated hospitals at Yaounde - Cameroon." Journal Africain d'Imagerie Médicale (J Afr Imag Méd). Journal Officiel de la Société de Radiologie d’Afrique Noire Francophone (SRANF). 14, no. 3 (December 19, 2022). http://dx.doi.org/10.55715/jaim.v14i3.389.
Dissertations / Theses on the topic "Défauts de radiation":
Huang, Liangzhao. "Multiscale modeling of the radiation-induced segregation in Ni-based and Fe-based dilute alloys." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP048.
We present a quantitative modeling of the point-defect (PD) redistribution and solute radiation-induced segregation (RIS) at extended defects in dilute Ni(B ≡ Ti, Cr) and Fe(B ≡ P, Mn, Cr, Si, Ni, Cu) alloys. The change in chemical composition, in the vicinity of extended defects, plays a decisive role on the evolution of the microstructure and mechanical properties of materials. Irradiation produces PDs, that diffuse by exchanging with neighboring atoms, annihilate by mutual recombination or by interacting with extended defects (that act as PD sinks). The fluxes of PDs towards sinks lead to atomic fluxes in the same or opposite direction of the PD flux; thereby producing RIS at sinks. We extend the self-consistent mean-field theory to forced atomic relocations (FARs), athermal diffusion mechanisms generated by displacement cascades under irradiation. The implementation of the extended theory in the KineCluE code allows us to compute PD and atomic fluxes, and their couplings. From the calculation of fluxes as a function of temperature, composition, and strain field; and a mean-field treatment of the production and annihilation reactions of PDs, we obtain the steady-state RIS profiles. In each of the particular kinetic regimes for which one of the PD reactions dominates over the others, we derive analytical expressions of steady-state profiles of PDs and solute atoms at planar sinks. To account for the effect of strain generated by an edge dislocation on the RIS and PD elimination rates, we numerically solve the elastodiffusion equations. Based on an ab initio database of binding energies, elastic dipoles, and atom-PD exchange frequencies, we perform a systematic study of the effects of the microstructure and irradiation conditions on diffusion properties, PD elimination rates at sinks, and RIS. We show that: (i) the dislocation loops are enriched in Ni in Fe(Ni) and depleted in Ti in Ni(Ti), and the calculated amounts of RIS are in good agreement with the experimental values measured in model Fe(Ni) and Ni(Ti) alloys irradiated by ions; (ii) at high flux, low temperature, and high sink strength, forced atomic relocations significantly reduce RIS, especially in Ni-based alloys; (iii) the temperature shifts calculated to simulate the effects of neutron irradiation by ion irradiation can be very different depending on the radiation-induced phenomenon, the kinetic regime in which the system evolves, and the chemical nature of the investigated alloy; (iv) the interactions between PDs and solute atoms change the absorption bias between vacancies and interstitials of an edge dislocation, as for instance, the addition of Ni leads to a negative bias while the addition of Mn increases the bias factor (up to 200% of the strained pure Fe value), depending on temperature and composition; (v) the dislocation strain field significantly increases Ni RIS (e.g., about 400% of the strain-free value at 400K) in Fe(Ni), and changes the sign of RIS in Fe(Cr)
Gérardin, Marie. "Etude du comportement thermique des gaz de fission dans l'UO₂ en présence de défauts d'irradiation." Thesis, Orléans, 2018. http://www.theses.fr/2018ORLE2051/document.
During in-reactor irradiation, fission gases such as xenon or krypton are produced. In the fuel, those gases diffuse and precipitate to form bubbles. In addition, fission reactions induce small defects(vacancies and interstitials) and larger defects (cavities and dislocations) formation. Data acquire menton fission gases migration considering radiation-induced defects is thus necessary to better understand and improve models of in-pile fuel behavior. The experimental approach developed in this work aims to study thermal diffusion of rare gases and to understand their interaction with radiation-induced defects.To do this, separated effect studies were performed coupling ion implantations/irradiations to fine characterization techniques. Positron Annihilation Spectroscopy (PAS) coupled to Transmission Electron Microscopy (TEM) observations allows for defects characterizations (vacancies and/or cavities induced by ion implantation) and for their thermal behavior study. On the other hand, gas release measurements are performed by thermal desorption spectrometry. Simulation of gas kinetic release allows to determine diffusion coefficients and to lighten trapping mechanisms. The synthesis of those various experimental results brings us to identify gas migration mechanism and to describe their interaction with radiation-induced defects
Arnolda, Pierre. "Lacréation de défauts de déplacements atomiques dans le silicium et son impact sur les composants électroniques à applications spatiales." Toulouse, ISAE, 2011. http://www.theses.fr/2011ESAE0016.
Goutaland, François. "Processus multiphotoniques, défauts ponctuels et mécanismes de leur formation dans les fibres optiques : étude par spectroscopie laser." Saint-Etienne, 1998. http://www.theses.fr/1998STET4021.
Jin, Xin. "Combining RBS/Channeling, X-ray diffraction and atomic-scale modelling to study irradiation-induced defects and microstructural changes." Thesis, Limoges, 2021. http://www.theses.fr/2021LIMO0017.
Energetic particles are involved in many activities of modern society. They constitute a significant aspect of the semiconductor industry and may play important role in shaping materials in a controllable way in the future. However, their energetic nature also poses grand challenges, especially in the nuclear industry. Thus, it is crucial to have a comprehensive understanding of the underlying mechanisms of irradiation-induced defects and the associated microstructural changes. Experimentally, irradiation-induced effects can be monitored by characterization techniques including, but not limited to, Rutherford backscattering spectrometry in channeling mode (RBS/C) and X-ray diffraction (XRD), because they are extremely sensitive to changes in the crystalline structure. However, it is not straightforward to establish a clear link between the characterization results and the defect quantity and nature, and this connection is usually made according to simple phenomenological models. In this thesis work, in order to cope with this problem, we performed RBS/C and XRD atomic-scale modelling. The first step was to improve a recently developed RBS/C simulation code that can generate RBS/C signals from arbitrary atomic structures. By modifying the algorithms describing ion-solid interactions and adding new features, we enhanced the flexibility of the code and its applicability to different types of materials. Subsequently, we employed the improved RBS/C code with a XRD program to compute disordering and elastic strain kinetics of a model material, namely UO2, as a function of irradiation fluence. Radiation defects in UO2 were simulated by molecular dynamics (MD) calculations. Both the strain and disordering kinetics exhibit qualitatively close agreement with those determined experimentally, indicating the validity of the used methodology. The decomposition of the kinetics was performed in order to study the effect of each defect separately, which enables a quantitative description of the disordering and strain build-up processes. Finally, we computed RBS/C and XRD signals from Fe MD cells, each of which contains one single type of defects. A clear comparison of disorder and elastic strain induced by different types of defects in Fe was made. The relation between RBS/C yield and He energy was also studied using the Fe MD cells, which shows dependency with defect types. The global approach used in this work has the hope to be extended and tested in more materials
Piochaud, Jean-Baptiste. "Modelling of radiation induced segregation in austenitic Fe alloys at the atomistic level." Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10024.
In pressurized water reactors, under irradiation internal structures are subject of irradiation assisted stress corrosion cracking which is influenced by radiation induced segregation (RIS). In this work RIS of 316 stainless steels is modelled considering a model ternary Fe–10Ni–20Cr alloy. For this purpose we have built an Fe-Ni-Cr pair interaction model to simulate RIS at the atomistic level using an atomistic kinetic Monte Carlo approach. The pair interactions have been deduced from density functional theory (DFT) data available in the pure fcc systems but also from DFT calculations we have performed in the Fe–10Ni–20Cr target alloy. Point defect formation energies were calculated and found to depend strongly on the local environment of the defect. As a consequence, a rather good estimation of these energies can be obtained from the knowledge of the number and respective positions of the Ni and Cr atoms in the vicinity of the defect. This work shows that a model based only on interaction parameters between elements positioned in perfect lattice sites (solute atoms and vacancy) cannot capture alone both the thermodynamic and the kinetic aspect of RIS. A more accurate of estimating the barriers encountered by the diffusing species is required than the one used in our model, which has to depend on the saddle point environment. This study therefore shows thus the need to estimate point defect migration energies using the DFT approach to calibrate a model that can be used in the framework of atomic kinetic Monte Carlo simulations. We also found that the reproduction by our pair interaction model of DFT data for the self-interstitial atoms was found to be incompatible with the modelling of RIS under electron irradiation
Tortech, Blandine. "Effets des radiations sur des fibres optiques dopées erbium : influence de la composition." Phd thesis, Université Jean Monnet - Saint-Etienne, 2008. http://tel.archives-ouvertes.fr/tel-00366057.
Piochaud, Jean-Baptiste. "Modelling of radiation induced segregation in austenitic Fe alloys at the atomistic level." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10024/document.
In pressurized water reactors, under irradiation internal structures are subject of irradiation assisted stress corrosion cracking which is influenced by radiation induced segregation (RIS). In this work RIS of 316 stainless steels is modelled considering a model ternary Fe–10Ni–20Cr alloy. For this purpose we have built an Fe-Ni-Cr pair interaction model to simulate RIS at the atomistic level using an atomistic kinetic Monte Carlo approach. The pair interactions have been deduced from density functional theory (DFT) data available in the pure fcc systems but also from DFT calculations we have performed in the Fe–10Ni–20Cr target alloy. Point defect formation energies were calculated and found to depend strongly on the local environment of the defect. As a consequence, a rather good estimation of these energies can be obtained from the knowledge of the number and respective positions of the Ni and Cr atoms in the vicinity of the defect. This work shows that a model based only on interaction parameters between elements positioned in perfect lattice sites (solute atoms and vacancy) cannot capture alone both the thermodynamic and the kinetic aspect of RIS. A more accurate of estimating the barriers encountered by the diffusing species is required than the one used in our model, which has to depend on the saddle point environment. This study therefore shows thus the need to estimate point defect migration energies using the DFT approach to calibrate a model that can be used in the framework of atomic kinetic Monte Carlo simulations. We also found that the reproduction by our pair interaction model of DFT data for the self-interstitial atoms was found to be incompatible with the modelling of RIS under electron irradiation
Kaddissy, Josiane. "Hydrogen production from irradiated aluminum hydroxide and oxyhydroxide." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS253/document.
Dihydrogen production is a critical issue for the current management of nuclear wastes. One potential source of hydrogen generation is the radiolysis of hydrated mineral phases encountered in the nuclear waste transportation and storage casks. We chose to study aluminum hydroxide (Al(OH)3) (Bayerite) and oxyhydroxides (AlOOH) (Boehmite) as model compounds. The determination of molecular hydrogen production was evaluated with respect to structure and particle size at room temperature and after annealing. In order to have a better understanding of the mechanisms and to identify the precursors of molecular hydrogen, we studied the irradiation defects and their stabilities using Electron Paramagnetic Resonance (EPR). The effect of adsorbed water and structural water on the molecular hydrogen production was studied. Different radiation sources were used such as Gamma radiation, electron beam radiations and heavy ions. In the last part, preliminary results related to the impact of impurities on hydrogen production are presented
Hongisto, Mikko. "Développement de verres et vitrocéramiques dopés ytterbium pour l'optique et réponses sous différents types de traitements." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0040.
This thesis studies the modification of the properties of glass compounds doped with Yb3+ ions, through variations in composition, thermal or radiation treatments as well as by immersion in aqueous medium. New Yb3+ doped oxyfluorophosphate glass/glass-ceramics have been developed and characterized to obtain fundamental information on crystallization. The study also proposes the development of cylindrical and rectangular bioactive fibers based on doped and non-doped borosilicate glass constituting the core and the clad of the fiber respectively. The stability of these fibers in aqueous medium is monitored according to the geometry. This study also provides information on resistance to defects depending on the nature of the network and on the development of new bioactive fibers, the emission of which could be used to follow the dissolution of the fiber in aqueous medium. This study contributes to a better fundamental understanding of how composition changes and thermal/radiation processes can modulate the performance parameters of glass materials doped by Yb3+ ions
Books on the topic "Défauts de radiation":
Wood, Roger M. Laser-induced damage of optical materials. Bristol: Institute of Physics, 2003.
Nsambayi, Lukusa. Droit judiciaire congolais: Définitions de lege ferenda des décisions de défaut-congé et de radiation grâce à l'analyse des concepts et expressions biffure, défaut-congé et radiation. Illustrations en matières de procédure civile et sociale congolaises. Paris: Harmattan, 2010.
Wood, Roger M., and R. M. Wood. Laser-Induced Damage of Optical Materials. Taylor & Francis Group, 2003.
Wood, Roger M. Laser-Induced Damage of Optical Materials. Taylor & Francis Group, 2003.
Wood, Roger M. Laser-Induced Damage of Optical Materials. Taylor & Francis Group, 2003.