Results 1 - 4 of 4
Results 1 - 4 of 4. Search took: 0.022 seconds
|Sort by: date | relevance|
[en] This article first proposes a presentation of the tidal theory and outlines the roles of Newton (to know the phenomenon), Laplace (to understand it) and Poincare (to act on it). The author then describes some tidal characteristics, notice than they can be different in different locations of the planet in frequency (two tides a day here, one tide a day there, or negligible) as well as in amplitude. Then, he addresses the history of cycles of use of tides, notably by exploiting the filling and emptying of basins by means of turbines (simple effect dam, double effect dam, pumping). He evokes some historical projects of tidal power plants in France, and then more particularly the Rance tidal power plant project, the Chausey and Minquiers projects. Article published in 'L'Astronomie' journal, Vol. 69, Dec. 1955, p.449-469.
[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] 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] After a description of the origin of nuclear energy, the author presents and describes a chain reaction using natural uranium, the notions of flows and cross sections, the multiplication factor, critical dimensions and the reflector role, the evolution of this multiplication factor and the notion of reactivity. He briefly describes a typical pile and its auxiliary components (power measurement, power control, safety). He proposes an overview of the characteristics of a conventional high-power pile, of experimental piles, and of a plutonium-producing pile. He discusses double function piles, the partial multiplication of resources, the threshold value of the conversion factor in a thermal neutron pile, fast neutron piles, and describes the use of uranium as a source of energy. He finally briefly discusses the price of a thermal reactor which produces electricity and plutonium. Reprint of a paper published in 'L'Onde Electrique', no. 321, Dec 1953, p. 1-8.