Abstract: A fuel cell with a proton-conducting membrane, on which catalyst material and a collector are arranged on both sides, is characterized by the following features: on the side facing the membrane (14), the collectors (16,18) are provided with an electrically conductive gas-permeable carbon aerogel with a surface roughness of <2 .mu.m; a catalyst layer (15, 17) of platinum or a platinum alloy is in each case applied to the carbon aerogel by material bonding; and a membrane (14), deposited by plasma-chemical means, with a layer thickness of between 3 and 50 .mu.m, is located between the catalyst layers (15, 17).

Abstract: In a fuel assembly, rods are disposed in meshes of a grid. Crossing points of the grid are distributed in a checker-board-like manner, partly in an upstream crossing plane and partly in a downstream crossing plane. Webs of the grid run in zigzag form between the two planes. As a result, flow resistance which is produced by the webs and/or by mixing vanes disposed thereon and by flow turbulences is shifted into different axial planes and is considerably reduced.

Abstract: A fuel assembly of a pressurized water nuclear reactor includes at least two fuel rods, respectively, having a cladding tube of given outer and inner diameters and pellets of given outer diameter received in the cladding tube, the fuel rods being disposed in the fuel assembly at a given mutual spacing of center points thereof, a ratio of the given mutual spacing of the center points of the fuel rods to the outer diameter of the cladding tube being in a range between 1.35 and 1.37.

Abstract: A fuel assembly for a pressurized water reactor includes fuel assembly edges and a fuel assembly interior. A bundle of mutually parallel fuel rods with cladding tubes each contain nuclear fuel. A given number of guide tubes are provided for control rods. A support structure includes an upper end with a fuel assembly head, a lower end with a fuel assembly foot, and a plurality of spacers disposed perpendicular to the fuel rods. The spacers have a uniform grid structure with edge meshes formed therein at the fuel assembly edges and inner meshes formed therein in the fuel assembly interior. Each of the inner meshes are surrounded by four respective immediately adjacent meshes each having the same area and each containing a respective one of the guide or cladding tubes or an instrumentation tube.

Abstract: A fuel assembly with a square cross section for water-cooled nuclear reactors, the fuel assembly having fuel rods disposed in a square array prescribed by spacers defining square grid meshes includes rods without fuel disposed, instead of the respective fuel rods, at individual positions of the square array distant from the marginal edge of the fuel-assembly cross section, for varying moderation ratio of the fuel assembly, the rods without fuel having a square cross section smaller than the cross section of the respective grid meshes only by a clearance sufficient for assembling the rods without fuel in the respective grid meshes and disassembling the rods without fuel from the respective grid meshes.

Abstract: An element for a core of a nuclear reactor, includes a square grid assembly formed of a plurality of spacers distributed over the length of the element, structural elements interconnecting the spacers, rods regularly disposed in the square grid assembly and surrounded by the spacers, including a plurality of the rods disposed at an edge of the core, and neutron-shielding material having a substantially square cross section respectively disposed in each of the plurality of rods at the edge of the core.

Abstract: A nuclear reactor-fuel element with cylindrical fuel rods and a fuel element skeleton formed of a head and foot member and cylindrical control rod-guide tubes connecting the members includes a plurality of mesh-forming spacing holder-grids for the fuel rods fastened to the guide tubes, the control rod-guide tubes being received respectively in the mesh formed by the spacing holder-grids, and flow guide means in vicinity of at least one of the spacing holder-grids largely closing, from a flow-technology standpoint, the cross section of the respective mesh surrounding the guide tube received therein.