205 research outputs found
La gestion des déchets nucléaires
La gestion des déchets nucléaires constitue pour le public un problÚme majeur et inquiétant bien que pour la majorité des acteurs du nucléaire, le stockage géologique soit une solution appropriée qui répond parfaitement aux légitimes exigences de sécurité. La loi de 1991 relative à la gestion des déchets nucléaires définit un cadre législatif qui a organisé pendant 15 ans les recherches sur ce sujet, et qui a pris soin d'y associer la société civile. Au vu des résultats obtenus, le parlement a voté en juin 2006 une nouvelle loi permettant de poursuivre et finaliser les recherches, avec pour objectif de proposer au parlement une solution industrielle pérenne à l'horizon 2015. AprÚs avoir appréhendé la complexité du sujet, les principaux acquis de la loi de 1991 seront présentés. Ils permettront d'une part de mieux comprendre les nouveaux enjeux des recherches actuelles et d'autre part de situer les solutions de gestion possible par rapport aux différents scénarios concernant la poursuite de l'utilisation de l'énergie nucléaire
Parametric Resonance in a Vibrating Cavity
We present the study of parametric resonance in a one-dimensional cavity
based on the analysis of classical optical paths. The recursive formulas for
field energy are given. We separate the mechanism of particle production and
the resonance amplification of radiation. The production of photons is a purely
quantum effect described in terms of quantum anomalies in recursive formulas.
The resonance enhancement is a classical phenomenon of focusing and amplifying
beams of photons due to D\"{o}ppler effect.Comment: 7 pages, 1 figure. to be published in Phys. Lett.
Invited letter to editor in response to: Finlandâs handling of selenium is a model in these times of coronavirus infections.
This response by the authors is in reply to a letter from Ulfberg and Stehlik (https://doi.org/10.1017/S0007114520003827) in comment to the authors' orginal article (https://doi.org/10.1017/S0007114520003128) that suggested that SE status was an important factor in determining the host response to viral infections
MURE : MCNP Utility for Reactor Evolution - Description of the methods, first applications and results
PACSInternational audienc
The Thorium Molten Salt Reactor : Moving on from the MSBR
A re-evaluation of the Molten Salt Breeder Reactor concept has revealed
problems related to its safety and to the complexity of the reprocessing
considered. A reflection is carried out anew in view of finding innovative
solutions leading to the Thorium Molten Salt Reactor concept. Several main
constraints are established and serve as guides to parametric evaluations.
These then give an understanding of the influence of important core parameters
on the reactor's operation. The aim of this paper is to discuss this vast
research domain and to single out the Molten Salt Reactor configurations that
deserve further evaluation.Comment: 11 pages, 8 figures, 6 table
Neutronic study of slightly modified water reactors and application to transition scenarios
International audienceIn this paper we have studied slightly modified water reactors and their applications to transition scenarios. The PWR and CANDU reactors have been considered. New fuels based on Thorium have been tested : Thorium/Plutonium and Thorium/Uranium- 233, with different fissile isotope contents. Changes in the geometry of the assemblies were also explored to modify the moderation ratio, and consequently the neutron flux spectrum. A core equivalent assembly methodology was introduced as an exploratory approach and to reduce the computation time. Several basic safety analyses were also performed. We have finally developed a new scenario code, named OSCAR (Optimized Scenario Code for Advanced Reactors), to study the efficiency of these modified reactors in transition to GenIV reactors or in symbiotic fleet
The single-nucleotide polymorphism (GPX4c718t) in the glutathione peroxidase 4 gene influences endothelial cell function : Interaction with selenium and fatty acids
© 2013 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Peer reviewedPublisher PD
Fast Thorium Molten Salt Reactors started with Plutonium
One of the pending questions concerning Molten Salt Reactors based on the 232Th/233U fuel cycle is the supply of the fissile matter, and as a consequence the deployment possibilities of a fleet of Molten Salt Reactors, since 233U does not exist on earth and is not yet produced in the current operating reactors. A solution may consist in producing 233U in special devices containing Thorium, in Pressurized Water or Fast Neutrons Reactors. Two alternatives to produce 233U are examined here: directly in standard Molten Salt Reactors started with Plutonium as fissile matter and then operated in the Th/233U cycle; or in dedicated Molten Salt Reactors started and fed with Plutonium as fissile matter and Thorium as fertile matter. The idea is to design a critical reactor able to burn the Plutonium and the minor actinides presently produced in PWRs, and consequently to convert this Plutonium into 233U. A particular reactor configuration is used, called unique channel configuration in which there is no moderator in the core, leading to a quasi fast neutron spectrum, allowing Plutonium to be used as fissile matter. The conversion capacities of such Molten Salt Reactors are excellent. For Molten Salt Reactors only started with Plutonium, the assets of the Thorium fuel cycle turn out to be quickly recovered and the reactors characteristics turn out to be equivalent to Molten Salt Reactors operated with 233U only. Using a combination of Molten Salt Reactors started or operated with Plutonium and of Molten Salt Reactors started with 233U, the deployment capabilities of these reactors fully satisfy the condition of sustainability
Production of photons by the parametric resonance in the dynamical Casimir effect
We calculate the number of photons produced by the parametric resonance in a
cavity with vibrating walls. We consider the case that the frequency of
vibrating wall is which is a generalization of other
works considering only , where is the fundamental-mode
frequency of the electromagnetic field in the cavity. For the calculation of
time-evolution of quantum fields, we introduce a new method which is borrowed
from the time-dependent perturbation theory of the usual quantum mechanics.
This perturbation method makes it possible to calculate the photon number for
any and to observe clearly the effect of the parametric resonance.Comment: 15 pages, RevTeX, no figure
Probing neutron-hidden neutron transitions with the MURMUR experiment
MURMUR is a new passing-through-walls neutron experiment designed to
constrain neutron/hidden neutron transitions allowed in the context of
braneworld scenarios or mirror matter models. A nuclear reactor can act as a
hidden neutron source, such that neutrons travel through a hidden world or
sector. Hidden neutrons can propagate out of the nuclear core and far beyond
the biological shielding. However, hidden neutrons can weakly interact with
usual matter, making possible for their detection in the context of low-noise
measurements. In the present work, the novelty rests on a better background
discrimination and the use of a mass of a material - here lead - able to
enhance regeneration of hidden neutrons into visible ones to improve detection.
The input of this new setup is studied using both modelizations and
experiments, thanks to tests currently performed with the experiment at the BR2
research nuclear reactor (SCKCEN, Mol, Belgium). A new limit on the
neutron swapping probability p has been derived thanks to the measurements
taken during the BR2 Cycle 02/2019A: at 95% CL.
This constraint is better than the bound from the previous passing-through-wall
neutron experiment made at ILL in 2015, despite BR2 is less efficient to
generate hidden neutrons by a factor 7.4, thus raising the interest of such
experiment using regenerating materials.Comment: 15 pages, 8 figures, final version, accepted for publication in
European Physical Journal
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