Abstract: Liquid-cooled nuclear reactor having a reactor pressure vessel and a reactor core of fuel assemblies received therein, the fuel assemblies being grouped into core cells each having a control rod containing absorber material and connected to a drive mechanism, including a sheetmetal shaft associated with the core cells, respectively, and extending beyond the length of the reactor core by a length at least equal to that of the respective control rod and having a cross section substantially equal to that of the respective core cell, the sheetmetal shaft being formed with longitudinal channels through which the fuel assemblies are loadable and unloadable.

Abstract: Fuel assembly for a nuclear reactor having a bundle of fuel rods of circular cross section extending parallel to one another and disposed at positions forming a raster, including a guide tube for a control rod extending parallel to the fuel rods in the bundle and occupying the positions for and having a cross section covering the cross section of a plurality of mutually adjacent fuel rods in the raster the cross section of the guide tube being defined by circular arcs conforming with those of the circular cross section of the adjacent fuel rods covered thereby and being connected by concave arcuate sections.

Abstract: Fuel-element spacer grid with a uniform grid field having polygonal grid-field units and grid crosspieces associated therewith, the grid crosspieces being formed with burls, fuel rods receivable in the respective grid field being centerable at the outer periphery of the fuel rods respectively, at centering surfaces of the burls of the grid crosspieces and retainable axially parallel to one another, the grid crosspieces having a transition region extending therefrom to the centering surfaces of the burls and formed with inclined surfaces for facilitating introduction and withdrawal of the fuel rods, the burls extending over only part of the axial length of the grid, and the inclined surfaces having an inclination angle .alpha. with respect to the grid plane and to a normal to the axis of the grid crosspiece such that the inclined surfaces, in turn, extend over only part of the axial length of the burls; and method of producing the spacer grids.

Abstract: A nuclear reactor, control rod holding latch permits rapid insertion of the control rod into a reactor core by a ratchet and pawl mechanism arranged to lock the control rod against withdrawal, this being done through a screw which by rotation permits slow withdrawal of the control rod from the core, while keeping the control rod locked against withdrawal other than through the screw action.

Abstract: In a fuel assembly for gas-cooled nuclear reactors, having a plurality of fuel rods fastened to a mounting plate formed with through bores serving as passageways for a coolant, the fuel rods having respective perforated end caps by which the fuel rods are connected to a fission-gas exhaust system, the end caps being formed with a respective external thread and being threadedly secured thereby in the mounting plate and simultaneously connected to the fission-gas exhaust system through channels formed in the mounting plate, the mounting plate and the end caps having surfaces formed thereon having a residual roughness of from 4 to 16 microns and being sealingly pressable against one another by the threaded connection between the end caps and the mounting plate, includes a threaded sleeve serving as means for threadedly securing the respective end caps to the mounting plate, the threaded sleeve being provided with means for gripping the sleeve by a tool and being formed with an internal thread in threaded engagem

Abstract: Fuel assembly for fast nuclear reactors includes a cluster of parallel-disposed fuel rods, and a casing surrounding the fuel rods and defining a coolant flow configuration, the fuel rods being disposed in a manner that the axes thereof intersect imaginary coaxial circles, and the casing being of circular cylindrical shape.

Abstract: A gas-cooled nuclear reactor, having a tight connection with an intentionally provided leak site between a fission-gas discharge channel formed in a reactor core carrying plate as well as in a head portion of encased fuel elements that are suspended in receiving bores formed in the core carrying plate, the tight connection being formed by an annular member having a sealing surface engaging the core carrying plate at a region thereof in which an opening to the fission-gas discharge channel formed in the core carrying plate is located, a gas-tight, elastic and substantially cylindrical member, variable in length, connecting the annular member to the fission-gas discharge channel formed in the head portion of the fuel element, compression spring means biasing the annular member in a direction away from the fission gas discharge channel formed in the fuel-element head portion, and a sealing abutment plate secured to a central pin and limiting clearance for play of the annular member with respect to an annular zon

Abstract: A reactor has a core formed by a plurality of laterally adjacent fuel assemblies, each assembly comprising a vertically elongated casing containing a bundle of fuel rods and having an upper end connected to a tubular suspension rod forming the primary suspension means for the casing, failure of this means permitting the fuel assembly to drop from the core. In each instance, an instrumentation tube having an upper end supported independently of the primary suspension rod, extends downwardly through the latter, and centrally through the casing to the lower end of the latter. This instrumentation tube and the fuel assemblies adjacent to each other remain suspended so as to form vertically fixed parts relative to any one assembly that might drop accidentally.

Abstract: A nuclear reactor fuel rod is disclosed in which fission gases from the nuclear reaction are retained for a short time period to permit decay of the radioactivity present in the gases and then permit the removal of the gases from the rod. To accomplish this one of the end caps of the rod has a hole drilled in it and is connected to a fission gas removal system in the reactor. A separate container, containing pressed filter material such as, activated carbon, is metallurgically connected to the perforated end cap. At least on the side of the filter into which the fission products initially pass, a porous element is used to permit the fission products to pass into the filter material in a finely divided state without a large pressure drop.

Abstract: A reactor core melt containment receptacle for use beneath a reactor core so that if the core overheats and melts and falls, the resulting core melt is contained by the receptacle, the latter having a bottom wall and an upstanding side wall, the latter being high enough so that the melt forms a melt level below its top. These walls are water-cooled to cool a melt in contact therewith. In addition, the receptacle has water-cooled elements extending upwardly from the bottom wall to above the melt level and spaced from the side wall. In this way heat is removed from the core melt both internally within the melt as well as via the receptacle bottom and side walls. The water-cooled elements extending above the melt level, absorb the heat radiated from the top surface of the melt, upward heat radiation being further reduced by transverse heat shields connected to the tops of the elements. Other features are included.

Abstract: A nuclear reactor fuel element comprised of a plurality of fuel rods disposed in a plurality of spacers in which the tubular casing for each fuel rod is designed without regard to the mechanical stress produced by the spacers and has a reinforced wall thickness adjacent to the spacers which is thicker than the wall thickness of the tubular casing in other areas not adjacent to the spacers. The spacers are arranged in a circular mesh with a center support rod.

Abstract: A gas-coolant nuclear breeder reactor includes a core enclosed by a pressure vessel having a bottom beneath the core potentially capable of burning through if the core melts due to excessive operating temperatures. A basin is positioned beneath the core, either outside or inside of the pressure vessel, to intercept the melted core. The heat of the melted core must be dissipated rapidly because the reactor is enclosed by a steel containment vessel which might be unable to resist the internal pressure that would otherwise result from the heat. Therefore, means are provided for conducting a fluid coolant cooling the metal core, in the basin, from the latter to an extended area of the inside of the steel containment vessel which, being of relatively high heat conductivity, conducts the heat from the coolant to the atmosphere outside of the containment vessel. Cooling water may be sprayed on the outside of this containment vessel to assist in the dissipation of the heat.