Results 1 - 8 of 8
Results 1 - 8 of 8. Search took: 0.016 seconds
|Sort by: date | relevance|
[en] Heavy water's superior moderating and neutron-economy characteristics give it an advantage over other moderators for use in natural uranium reactors. Despite its high cost, the use of heavy water is warranted because of the scarcity of enriched uranium and plutonium. Reprint of a paper published in 'Nucleonics', vol.11, no. 12, Dec 1953, p. 10-14.
[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] By integrating the technical chronology with the philosophies underlying construction of the Saclay reactor, the director of the project paints the best available picture of the French advance towards nuclear power. Reprint of a paper published in Nucleonics, Vol. 12, No. 8, August 1954, p. 8-11.
[en] This conference raises an inventory of industrial applications and their perspectives for the year 1955. The speaker extrapolate for the forthcoming years the evolution of the role of the nuclear, the nuclear fuel, the different, types of atomic reactors and the state of advancement for different countries. (M.B.)
[fr]Cette conference dresse un etat des lieux des applications industrielles et de leurs perspectives pour l'annee 1955. L'orateur aborde entre autre l'evolution du role du nucleaire dans les annees a venir, le combustible nucleaire, les differents types de piles atomiques et l'etat d'avancement des differents pays. (M.B.)
[en] It brings together the techniques data which are involved in the discussion about the utility for a research institute to acquire an atomic reactor for research purposes. This type of decision are often taken by non-specialist people who can need a brief presentation of a research reactor and its possibilities in term of research before asking advises to experts. In a first part, it draws up a list of the different research programs which can be studied by getting a research reactor. First of all is the reactor behaviour and kinetics studies (reproducibility factor, exploration of neutron density, effect of reactor structure, effect of material irradiation...). Physical studies includes study of the behaviour of the control system, studies of neutron resonance phenomena and study of the fission process for example. Chemical studies involves the study of manipulation and control of hot material, characterisation of nuclear species produced in the reactor and chemical effects of irradiation on chemical properties and reactions. Biology and medicine research involves studies of irradiation on man and animals, genetics research, food or medical tools sterilization and neutron beams effect on tumour for example. A large number of other subjects can be studied in a reactor research as reactor construction material research, fabrication of radioactive sources for radiographic techniques or applied research as in agriculture or electronic. The second part discussed the technological considerations when choosing the reactor type. The technological factors, which are considered for its choice, are the power of the reactor, the nature of the fuel which is used, the type of moderator (water, heavy water, graphite or BeO) and the reflector, the type of coolants, the protection shield and the control systems. In the third part, it described the characteristics (place of installation, type of combustible and comments) and performance (power, neutron flux ) of already existing type of reactors: low power reactors, graphite and natural uranium reactors, heavy water and natural uranium reactors (with water, gas or heavy water as coolant), heavy water and enriched uranium reactors, 'kettle' type reactors, pool type reactors and high power reactors. Finally, additional factors are considered as the correlation of the reactor type with the research program, safety considerations, size of the construction and economical considerations. (M.P.)
[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.