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[en] The danger of the uranium cans sur-activated by the use in the nuclear reactors is triple: - Irradiation from afar, during manipulations of the cans. - Contamination of air when decladding. - Contamination of air by fire of uranium in a reactor in function The first two dangers are usual and can be treated thanks to the rules of security in use in the atomic industry. The third has an accidental character and claimed for the use of special and exceptional rules, overflowing the industrial setting, to reach the surrounding populations. (authors)
[fr]Le danger des cartouches d'uranium suractive par utilisation dans les reacteurs nucleaires est triple: - Irradiation a distance, lors des manipulations des cartouches. - Contamination de l'air au moment de leur degainage. - Contamination de l'air par incendie d'uranium dans un reacteur en fonctionnement. Les deux premiers dangers sont habituels et peuvent etre traites grace aux regles de securite en usage dans l'industrie atomique. Le troisieme revet un caractere accidentel et reclame l'emploi de regles speciales et exceptionnelles, debordant le cadre industriel, pour atteindre celui des populations environnantes. (auteurs)
[en] The actual CEA program is concerned with the construction of two large graphite reactors, each of those containing at least one hundred tons of uranium metal with nuclear purity. The uranium for these two reactors will be regularly supplied by new resources discovered in France and Madagascar in the last five years. The working and treatment of such ore have led to the creation of an important french industry of which the general outline and principle are described. The operated ores have got different natures and concentration, individual characteristics are described for the main ores.The most high-grade ore are transported to a central plant in Bouchet near Paris; the low-grade ore are concentrated by physical methods or chemical processes of which principles and economy are studied with constancy. The acid processes are the only used until now, although the carbonated alkaline processes has been studied in France. The next following steps after the acid process until the obtention of uranium rich concentrate are described. The purification steps of uranium compounds to nuclear purity material are described as well as the steps to elaborate metal of which the purity grade will be specify. Finally, the economic aspects of uranium production difficulty will be considered in relation with technical progresses which we can expect to achieve in the future. (M.P.)
[en] The author reports the use of the Nordheim formula in the case of Zoe (a pile located in Chatillon), while considering the case bars in natural uranium (instead of UO2), and while taking the effect of geometry on photo-neutron production into account. The Nordheim formula is calculated for two different experimental values of the constants of delayed neutrons. The author discusses the difference between the results obtained for reactivity with these new conditions and with the older ones. He reports the calculation of the geometrical factor
[en] After having published during the year 1953 several articles on atomic piles, written by engineers of the CEA, which gave very interesting information on the construction, the operation and the control of the pile, and at a time when all nations are considering the peaceful uses of atomic energy, this series of articles is concluded by a remarkable study of Mr. Kowarski, one of the most well-known specialists, on using atomic piles for the generation of electrical energy; after a review of uranium nuclear properties this paper gives a clear picture of the opportunities that are available today and those that may be considered in the near future: pure fissile matter combustion, pure fissile matter simultaneous combustion and production, power and plutonium production from natural uranium, natural uranium piles that solely produce power. Reprint of a paper published in 'Electricite' journal, Jan 1954, p. 3-8.
[fr]Nous avons eu le plaisir de publier au cours de l'annee 1953 plusieurs articles sur les piles atomiques, rediges par des ingenieurs du Commissariat de l'Energie Atomique, qui ont donne de tres interessants renseignements sur la construction, le fonctionnement et le reglage des piles. A l'heure ou toutes les nations envisagent les utilisations pacifiques de l'energie atomique, nous sommes heureux de conclure cette serie d'articles par une etude remarquable de M. Kowarski, l'un des specialistes les plus connus, sur l'emploi des piles atomiques pour la production de l'energie electrique. Il y fait le point avec precision des possibilites qui s'offrent actuellement a nous et de celles qu'on peut envisager dans un avenir prochain. Reproduction d'un article publie dans 'Electricite', janvier 1954, p. 3-8.