[en] The CEA actually constructs the G-2 reactor core working with natural uranium, which will use graphite as moderator, and gas under pressure as cooling fluid. This report presents the specificity of the new reactor: - the different elements of the reactor core, - the control and the security of the reactor, - the renewal of the fuel, - the biologic surrounding wall, - and the cooling circuit. (M.B.)

[en] It is declared understood in the pension laws that manage the Jubilations and Pensions Office of the Industry and Commerce the personnel that has lent or lend services in the Laboratories of Clinical analysis and in clinics radiological matters

[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)

[en] The present publication, includes 9 articles, the purpose of this commission objective shall be secure for the state the utilisation of atomic energy for peaceful purposes

[en] The authors propose an overview of the history and development of atomic piles. They first describe the process of evolution from the discovery of radioactivity to the creation of the first atomic pile (emergence of nuclear physics, to draw usable energy from matter, to achieve a chain reaction from uranium fission, creation of atomic piles). They describe various aspects of a typical atomic pile, such as the Chicago's one, by describing operating conditions, practical achievements, the pile control, implemented safeties, power measurement, high power piles, pile lifetime, and personnel protection. Then, they address the use of experimental piles, notably for plutonium production (brief description of some piles, description of the Chatillon pile and of Bepo). They propose an overview of the current status of pile technology (consequences of first acquisitions, trends of evolution), and present some new piles (Lopo-Hypo piles, Los Alamos fast reactor). They give an overview of the main innovations published and implemented in 1952. Reprint of a paper published in 'Electricite' journal, March 1953, p. 3-11.

[en] The author first presents some generalities on the cooling of nuclear reactors, notably in the case of the Saclay pile. He evokes performed calculations, discusses the choice of the cooling fluid. In the next part, he more particularly addresses the case of the cooling circuit of the Saclay reactor: circulation of pressurised nitrogen for the cooling of active bars, blower, control of nitrogen flow rate, personnel safety, heavy water circuit for the cooling of the heavy water vessel. The author then addresses the installation electricity supply: sources, contactors and switches, control console, auxiliary equipment, engines and machines. He describes the operation of electrical installations on main power and in case of emergency-run. Reprint of a paper published in 'L'Onde Electrique' journal, no. 321, dec 1953.

[en] In a nuclear reactor including the bars or plates cooled by a gaseous fluid, burst risks to occur in the sheath assuring the tightness separation between the cooling gas and the fissile materials. It is necessary to be able to detect the formation of these cracks as possible in order to avoid all risk of fission products release or any reaction of uranium to the contact of the refrigerating gas. It is however the increase of the radioactivity in the cooling gas due to the scattering of the fission products that permits to signal the apparition of a crack or to follow its evolution. It is possible to detect cracks of the order of the square millimeter. In this report, we will detail the principle and the realization of a device used for the surveillance of a natural uranium reactor cooled by air circulation. (M.B.)

[en] This paper gives a description of the control installations of the Saclay reactor, a heavy water - natural uranium reactor. The various equipment described here are: ionization chamber, pre-amplifier, amplifier, recording system, safety system, power regulation, power system, heavy water system and control, reactivity measurement, radiation monitoring, temperature measurement, thermodynamic measurements, 'leakage' measurement, safety circuit. Reprint of a paper published in 'L'Onde Electrique' journal, no. 321, dec 1953.

[en] The use of nuclear reactor for energy production induces the installation of automatic control systems which need to be safe enough and can adapt to the industrial scale of energy production. These automatic control systems have to insure the constancy of power level and adjust the power produced to the energy demand. Two functioning modes are considered: nuclear plant connected up to other electric production systems as hydraulic or thermic plants or nuclear plants functioning on an independent network. For nuclear plants connected up with other production plants, xenon poisoning and operating cost lead to keep working at maximum power the nuclear reactors. Thus, the power modulation control system will not be considered and only start-up control, safety control, and control systems will be automated. For nuclear power plants working on an independent network, the power modulation control system is needed to economize fuel. It described the automated control system for reactors functioning with constant power: a power measurement system constituted of an ionization chamber and a direct-current amplifier will control the steadfastness of the power produced. For reactors functioning with variable power, the automated power control system will allow to change the power and maintain it steady with all the necessary safety and will control that working conditions under P_max and R_max (maximum power and maximum reactivity). The effects of temperature and xenon poisoning will also be discussed. Safety systems will be added to stop completely the functioning of the reactor if P_max is reached. (M.P.)