36 research outputs found
Histoire d'un livre : l'Histoire de France de Victor Duruy
No full textInternational audienceJean-Charles Geslot sets out to tell the story of an emblematic book of the 19th century, from its conception by its author to its reception by the public, painting a vivid picture of a publishing world in the throes of change.The book in question is a History of France: published in 1858, it enjoyed a success worthy of Michelet or Lamartine, and was reprinted several times until the First World War. Its author, Victor Duruy, historian, Minister of Public Instruction, played a part in the construction and dissemination of the 'récit national', taking advantage of the rise of school publishing and the popularisation of history.Unravelling, step by step, all the threads that go to make up a book, the author investigates, in the historian's and publisher's offices as well as in the workshops of the ink and paper manufacturers; he describes the work of ragmen and printers, stitchers and bookbinders, and takes us into the bookshops and libraries; He meets the readers, schoolchildren and teachers, townsfolk and countrywomen, scholars and even convicts, from Chartres to Nouméa, from New York to St Petersburg, and immerses us in the debates of the time between critics and journalists on their visions of France.Offering an original synthesis, this cultural history essay plunges us into the ways in which books were produced and circulated, and the reading practices of the second 19th century.Faire l’histoire d’un livre emblématique du XIXe siècle, de sa conception par son auteur à sa réception par le public, c’est ce à quoi s’attelle ici Jean-Charles Geslot, en dressant le tableau vivant d’un monde de l’édition en pleine mutation.Le livre en question est une Histoire de France : paru en 1858, il a connu un succès digne de Michelet ou de Lamartine, et été plusieurs fois réédité jusqu’à la Première Guerre mondiale. Son auteur, Victor Duruy, historien, ministre de l’Instruction publique, participe ainsi à la construction et à la diffusion du récit national, en profitant de l’essor de l’édition scolaire et de la vulgarisation historique.Dénouant, étape après étape, tous les fils de ce qui fait le livre, l’auteur mène l’enquête, dans les bureaux de l’historien et de l’éditeur comme dans les ateliers des fabricants d’encre et de papier ; il nous décrit à l’œuvre chiffonniers et imprimeurs, brocheuses et relieurs, et nous fait entrer dans les librairies et les bibliothèques ; il va à la rencontre des lecteurs et des lectrices, écoliers et professeurs, citadins et paysannes, érudits et même bagnards, de Chartres à Nouméa, de New York à Saint-Pétersbourg, et nous plonge dans les débats de l’époque opposant critiques et journalistes sur leurs visions de la France.Proposant une synthèse originale, cet essai d’histoire culturelle nous plonge dans les modes d’élaboration et de circulation du livre et les pratiques de lecture du second XIXe siècle
Method development for discrimination of anodic and cathodic signals in miniature fission chambers for reactor physics applications
No full textIn 2014, a measurement campaign was made at CEA Cadarache using different versions of a high sensibility miniature fission chamber prototype with two fissile layers. The current project studies the possibilities of discrimination between signals coming from a fission in the fissile layer covering the anode or in the fissile layer covering the cathode. A specific fission chamber simulation tool, named Trace, has been developed. Simulation results show the feasibility of discrimination based on pulse shape. A machine learning classification al- gorithm is applied to the available measurement data. Misleading discrimination parameters are identified and the limits of the possible use of the current data for discrimination pur- poses are highlighted. A promising criterium based on the pulse convexity is presented, and recommendations for the development of a future optimized detector are given.LRSHosted by LRS and CEA Cadarach
Correction factors to apply to fission rates measured by miniature fission chambers in various neutron spectra
No full textCEA develops and makes use of miniature fission chambers (MFCs, with radius down to 1.5 mm) for reactor physics conducted in experimental reactors such as EOLE and MINERVE zero power reactors (CEA Cadarache). When measuring fission rate, it is known that the neutron spectrum in the irradiation channel can be modified by the detector and the detector fixture. So the result of the measurement does not give a direct access to the desired quantity (fission rate, neutron flux,etc.) To overcome this problem, it is possible to make use of Monte Carlo calculations based on a detailed modeling of the detector. It could then be included in the 3D reactor model but this leads to large and time consuming calculations. In this case, measurement results can be combined directly with calculated values to produce the desired quantity. Another possibility is to calculate correction factors to apply to the biased measurement, i.e. to perform two-step calculations. Those factors depend on the detector geometry, the neutron spectrum and the fissile isotope at stake. A method to determine those factors is presented in this paper. The previously calculated neutron spectrum is fed to a simplified calculation route that includes only the detector and its close environment. Correction factors are obtained from two calculations results (with and without the detector fixture). In this case, the measured fission rates are corrected before being further processed. This paper details a parameter study on the impact of MFC parts and its environment (cable, connector) on the observed fission rate. Precise models of CEA-made MFCs have been developed for that purpose and used to produce correction factors for various fissile isotopes and neutron spectra. It is shown that fission rates can be greatly underestimated because of neutron radiative capture in MFC parts close to the fissile coating (9% in the worst case). The impact on standard reactor physics measurements is then discussed.IPHY
Review of kinetic modulation experiments in low power nuclear reactors
No full textInternational audienceThe safety improvement of nuclear reactors requires continuous efforts in understanding the fundamental physical quantities related to the fission process. In neutronic models, the reactor dynamics is covered by the kinetic parameters to characterize the temporal behavior of the neutron population subject to perturbations. The reactor transfer function is a frequency domain analogy of this temporal description. It can be measured experimentally through transfer function analysis via noise analysis or kinetic modulation, for the study of reactor stability and kinetic parameters. This paper summarizes the experimental measurements of reactor transfer function through kinetic modulation. Extensive work have been conducted experimentally, starting from the beginning of reactor physics research. An overview is given regarding various experimental designs and conducted analyses. The concepts of the modulation system are also discussed. The current work is limited to online contents and internal archives of CEA Cadarache due to difficulties in accessing references traced back to 1950s
Thermal neutron activation experiments on Ag, In, Cs, Eu, V, Mo, Zn, Sn and Zr in the MINERVE facility
No full textInternational audienceThe MAESTRO experimental program has been designed to improve nuclear data uncertainty on a large range of materials used for detection, absorption, moderation and structures in LWRs. It consists of pile-oscillation and neutron activation experiments, carried out in the MINERVE low power facility. For this program, the core configuration has been designed to be representative of HZP (Hot Zero Power) conditions of a typical PWR. Samples of high purity elements have been manufactured with severe technological constraints to reach a target accuracy of 2% (1) on the measurement. This paper presents a preliminary analysis of activation experiments, based on TRIPOLI4 Monte-Carlo calculations and various nuclear data libraries
Thermal neutron activation experiments on Ag, In, Cs, Eu, V, Mo, Zn, Sn and Zr in the MINERVE facility
No full textThe MAESTRO experimental program has been designed to improve nuclear data uncertainty on a large range of materials used for detection, absorption, moderation and structures in LWRs. It consists of pile-oscillation and neutron activation experiments, carried out in the MINERVE low power facility. For this program, the core configuration has been designed to be representative of HZP (Hot Zero Power) conditions of a typical PWR. Samples of high purity elements have been manufactured with severe technological constraints to reach a target accuracy of ±2% (1σ) on the measurement. This paper presents a preliminary analysis of activation experiments, based on TRIPOLI4 Monte-Carlo calculations and various nuclear data libraries
Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop
No full textPile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop) and another one where the power is free to drift (open loop). First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples
Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop
No full textPile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop) and another one where the power is free to drift (open loop). First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.</jats:p
