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: Device for holding jacketed fuel assemblies of a gas-cooled nuclear reactor in a grid plate disposed beneath a reactor core and formed with cylindrical bores for receiving therein a respective fuel-assembly foot which serves simultaneously as a coolant inlet, including a tubular grid-plate insert member connected respectively to each of the bores for hydraulically holding down the respective fuel assemblies against flow pressure of the coolant, the insert member being closed at the bottom thereof and having at least one lateral opening for passage of coolant to the respective fuel-assembly foot, piston rings peripherally disposed on the fuel-assembly foot above and below the lateral opening for sealing the foot with respect to the inner surface of the insert member, a plurality of wedge-like structural members uniformly distributed about the periphery of the fuel-assembly foot above the lower of the piston rings, and a piston central to the foot and actuatable by a pressure difference of the coolant between a

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