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[en] A burnable poison rod for use in a nuclear reactor comprising an elongated tubular sheath enclosing a neutron absorbing material, characterized in that at least during operation of said reactor said sheath also encloses a neutron moderating material is described
[en] Purpose: To enable the selection for the control range and control accuracy of reactivity over a wide range in a device for controlling the reactor activity by adjusting the amount of fluid poison flowing in fluid poison control pipes in heavy water moderated reactors. Constitution: In a device for controlling the core reactivity by vertically providing a plurality of fluid poison control pipes each formed with a coaxial double tube whose inner tube is formed with communication apertures, the communication apertures are formed in a plurality of positions at different heights in the inner tube. Flow channel switching valves capable of flowing the fluid poison from either one of the inner region or the outer region separated by the inner tube are provided. The amount of the fluid poison and the introducing region thereof are varied by the operation of the switching valves. (Ikeda, J.)
[en] The appearance of efflorescences constitutes a serious problem for ceramic roofing tile quality, since efflorescences affect roofing tile technical and aesthetic qualities. This paper describes a method of determining the soluble salts present in the raw materials used in ceramic roofing tile manufacture and in the resulting roofing tiles, as well as an analysis of the phases in roofing tile efflorescences. The study was divided into three parts. First, a method of determining the soluble salts was developed, optimising the extraction method and fine-tuning an anion measurement method by ionic chromatography. Secondly, the changes in solubility, as well as the chemical and structural changes that occurred when the raw materials were subjected to firing, were studied. Finally, the efflorescences of a group of unfired and fired ceramic roofing tiles were characterised, in order to relate them to the quantity and type of soluble salts contained. The study concludes that it is necessary to conduct solubility tests on fired samples under real conditions, since important structural changes occur in the firing process, which lead to considerable variations in the soluble salts. Furthermore, in addition to analysing Na(I), K(I), and Mg(II) as indicated in the standard, it is advisable to determine Ca(II) and SO42-, since these are the major components in the efflorescences. (Author)
[en] An elongated nuclear reactivity control member, a releasable latching structure useful for releasably attaching the control member at an end to a top nozzle adapter plate of a nuclear fuel assembly is described comprising: (a) a mounting body including an inner plug portion attached to the end of the control member and an outer end portion disposed axially outward from the inner plug portion and the end of the member; and (b) a spring latch disposed about the mounting body and being attached to the outer end portion. The spring latch has at least one latch finger extending toward the inner plug portion of the body and is movable toward and away from the body between an outer latching position in which the finger is adapted to engage a fuel assembly top nozzle adapter plate and retain the elongated member in a stationary relationship with respect to the adapter plate and an inner unlatching position in which the finger is adapted to disengage from the adapter plate and allow removal of the member from the adapter plate
[en] Object: To determine rate of change in reactivity using the integrating power and core flow rate as parameters, to detect the reactivity with high accuracy. Structure: By start signals from an input processor started periodically by means of a timer to incorporate integrating power and core flow rate, a minimum involution operator calculates and outputs a flow rate - reactivity gradient, a secondary operator calculates and outputs a reactivity - flow rate gradient, a reactivity coefficient deciding device decides the reaction coefficient, and a reactivity counter calculates and outputs a changed portion of reactivity. (Kawakami, Y.)
[en] This invention concerns the improvements made to nuclear reactor fuel assemblies, in particular to the procedures and appliances for removably setting up, in the cross-bracing of fuel assemblies, rods of neutron absorbing burnable substances also called 'poisons'
[fr]La presente invention concerne des perfectionnements apportes aux ensembles de combustible de reacteur nucleaire, et, plus particulierement, des procedes et appareils en vue de monter de facon amovible dans les croisillons d'ensembles combustibles des barreaux de substances consommables d'absorption de neutrons, substances appelees aussi 'poisons'