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[en] The nuclei of isotopic atoms contain as many protons, but neutrons in different numbers; therefore, isotopic atoms have different nuclear characteristics, whereas they are hardly distinguishable by their other properties. The fact that an isotope industry has been born and developed vigorously is one of the signs of our entry into the nuclear age. After a brief review of the fundamental theoretical notions, some general characteristics of isotopic separations are presented. Then, the separation of uranium-235 by gaseous diffusion and various modes of preparation of heavy water, are briefly described, while insisting on the unsolved problems and on various economic and industrial aspects of these processes. Reprint of a paper published in 'L'Industrie Nationale', April-June 1955, p. 27-36
[fr]Des atomes sont dits isotopes lorsqu'ils appartiennent a un meme element, mais ont des masses differentes. Dans le langage actuel, les noyaux de ces atomes contiennent autant de protons, mais des neutrons en nombres differents. Nous ne serons donc pas surpris que des atomes isotopes aient des caracteristiques nucleaires differentes, souvent meme tres differentes, alors qu'ils se distinguent a peine par leurs autres proprietes. Le fait qu'une industrie des isotopes est nee et se developpe avec vigueur depuis dix ans est un des signes de notre entree dans l'ere nucleaire. Apres un bref rappel des notions theoriques fondamentales, je vais ce soir vous presenter certains caracteres generaux des separations isotopiques. Decrivant ensuite sommairement la separation de l'uranium-235 par diffusion gazeuse et divers modes de preparation de l'eau lourde, j'insisterai sur les problemes non resolus et sur divers aspects economiques et industriels de ces processus. Reproduction d'un article publie dans l'Industrie nationale, avril-juin 1955, p. 27-36
[en] In this article, L. Kowarski, at the time (1952) in charge of the Department of Reactors and Accelerators at the Atomic Energy Commission (CEA), reviews the scientific and industrial advances made in the field of production and use of atomic energy (experimental reactors, interest of heavy water reactors, plutonium production, choice of a moderator and a cooling fluid, power generation) and examines the different directions in which the program of atomic works should be pursued in France. L. Kowarski published in 'La Technique Moderne' journal previous articles such as: 'The very high voltages and their application to elements transmutation' (February 15, 1939), and 'Atomic Energy. Present state and application prospects' (February 15, 1947). Reprint of a paper published in 'La Technique Moderne', t. XLIV, no. 5, May 1952.
[fr]Dans le tres bel article ci-dessous, M. Kowarski, actuellement charge au Commissariat a l'Energie Atomique du 'Departement des Piles et Accelerateurs', fait le point des progres scientifiques et industriels realises dans le domaine de la production et de l'utilisation de l'energie atomique, et examine les differentes directions dans lesquelles pourrait etre oriente le programme des travaux atomiques a poursuivre en France. Il n'est pas necessaire de presenter M. Kowarski aux lecteurs de La Technique Moderne. Ils ne manqueront pas de se reporter a ses precedents articles parus dans notre revue, et en particulier a ceux du 15 fevrier 1939: Les tres hautes tensions et leur application a la transmutation des elements, et du 15 fevrier 1947: L'energie atomique. Etat present et perspectives d'application. Reproduction d'un article publie dans 'La Technique Moderne', t. XLIV, no. 5, mai 1952.
[en] After a brief recall of a few concepts (mass number, charge and beams properties) and the description of used detectors (ionization chamber, Geiger-Mueller counter, scintillation counters), some radionuclides applications are described. In a first part, the well-developed applications are presented in three distinct groups: continuous applications such as β and γ gauges (determination hydrogen content of an hydrocarbon and content of an emulsion; discharge of static electricity), discontinuous applications such as radiography and autoradiography, wear or manufacture problems (distribution of a fungicide on tobacco) and finally, applications in research laboratories such as diffusion, exchange and solubility. It also describes the applications which are still in development such as the action of beams on matter (reticulation and degradation of polymers, monomers polymerisation, cold sterilization). In conclusion, few advices on the opportunity of such applications and the choice of the radionuclides are given. (M.P.)
Nuclear energy and its industrial applications. 1 - Atomic piles and radio-isotopes: The French atomic programme; The future of atomic energy; The Nuclear Study Centre of Saclay; Fundamental notions related to nuclear reactors; Neutron spectrometer used in the Saclay pile; Determination of the transport mean free path of thermal neutrons by measuring a complex length of diffusion; Electronic equipment used in the measurement of the diffusion length in graphite; The non destructive materials test using the oscillation method in the Chatillon pile; An analogue harmonic analyser; Recent progress in reactor control; Analogue calculators pile simulators; The preparation of artificial radio-elements; Problems faced in the prospecting of radioactive ores and used equipment; Radioactive aerosols and gases in the atomic industry; A fixed health monitoring installation at the Laboratoire de Haute Activite of Saclay
[en] This publication gathers several articles which address various aspects of atomic piles and radio-isotopes. More particularly, the addressed topics are: the future of atomic energy; a presentation of the Nuclear Study Centre of Saclay; an introduction to nuclear engineering; a study of the interaction of neutrons with various elements as a function of neutron velocity; a determination of the transport mean free path of thermal neutrons by measuring a complex length of diffusion; the electronic equipment used in the measurement of the diffusion length in graphite; the non destructive test of materials using the oscillation method in the Chatillon pile; an analogue harmonic analyser; recent progress in reactor control; analogue calculators pile simulators; the preparation of artificial radio-elements; the preparation of artificial radio-elements; a general review of radioactive survey equipment; radioactive aerosols and gases in the atomic industry; A fixed health monitoring installation at the High Activity Laboratory of Saclay. Reprint of a dossier published in 'L'Onde Electrique', Vol. XXXV, No. 343, October 1955, p. 783-947
[en] Countries with large stock of fissile material and producing large quantity of nuclear pure 235U and 239Pu are able to allocate part of the stock to non military research. For countries with low stock of fissile material, all the stock is allocated to military research. An economical and technical solution has to be find to dedicate a part of fissile material to non military research and develop the atomic energy industry. It stated the industrial and economical problems and in particular the choice between the use of enriched fuel with high refining cost or depleted fuel with low production cost. It discusses of four possible utilizations of the natural resources: reactors functioning with pure fissile material (235U or 239Pu) or concentrated material (235U mixed with small quantities of 238U after an incomplete isotopic separation), breeder reactors functioning with enriched material mixed with 238U or Thorium placed in an appropriate spatial distribution to allow neutrons beam to activate 238U or Thorium with the regeneration of fissile material in 239Pu, reactors using natural uranium or low enriched uranium can also produce Plutonium with less efficiency than breeder reactors and the last solution being the use of natural uranium with the only scope of energy production and no production of secondary fissile material. The first class using pure fissile material has a low energy efficiency and is used only by large fissile material stock countries to accumulate energy in small size fuel for nuclear engines researches for submarines and warships. The advantage of the second class of reactors, breeder reactors, is that they produce energy and plutonium. Two type of breeder reactor are considered: breeder reactor using pure fissile material and 238U or breeder reactor using the promising mixture of pure fissile material and Thorium. Different projects are in phase of development in United States, England and Scotland. The third class of reactor using natural uranium as fuel are presented as a possibility for double-function reactor with the production of plutonium and energy, but the neutron balance is lower than with breeder reactor. One solution is to increase the temperature of functioning but it induces to change the structure materials and moderators. Different solutions are discussed about the utilization of graphite or heavy water as moderators. The last class of reactors using natural uranium and producing only energy is considered by countries with no uranium stock, the energy efficiency and balance, as well as the costs, are then of more importance. Finally, it presented conclusions about the different economic strategies about the industrial development of atomic energy in countries with and without fissile material resources. (M.P.)
[en] A method of measuring neutron density is presented. It consists of autoradiography, by β rays of the thin detector, irradiated in the neutron flux to be studied. The blackening density obtained by the β rays is then measured with a microdensitometer. The main interest of the method lies in the fact that one can obtain a power of resolution definitely superior to that which one obtains with other methods (G.M. detector-meter, boron ionization chamber, etc.). An example of an application is given. Reprint of a paper published in 'Comptes Rendus des Seances de l'Academie des Sciences', t. 23, sitting of May 12, 1952, p. 1969-1971.
[fr]On presente une methode de mesure de densite de neutrons. Elle consiste a faire l'autoradiographie, par rayons β du detecteur mince, irradie dans le flux de neutrons a etudier. On donne un exemple d'application. Reproduction d'un article publie dans les 'Comptes Rendus des Seances de l'Academie des Sciences', t. 23, seance du 12 mai 1952, p. 1969-1971.
[en] Inelastic scattering of the β- particles on the nucleus gives place to the emission of a X-ray Bremsstrahlung radiation. In view of possible industrial applications, we studied the slowing-down radiation of 90(Sr + Y) sources in various materials. This pure β- emitter of long period is in the fission products of uranium. Among of the industrial applications, these sources of weak X-rays energy can be used for the radiography of thin pieces, for measuring the thickness, or for the analysis by fluorescence. (M.B.)
[fr]La diffusion inelastique des particules β- sur les noyaux donne lieu a l'emission d'un rayonnement X de freinage. En vue de possibles applications industrielles, nous avons etudie le rayonnement de freinage des sources 90(Sr + Y) dans divers materiaux. Cet emetteur β- pur a longue periode se trouve dans les produits de fission de l'uranium. Parmi les applications industrielles a l'etude, ces sources de rayons X de faible energie peuvent etre utilisees pour la radiographie de pieces minces, la mesure d'epaisseurs, ou encore pour l'analyse par fluorescence. (M.B.)