Abstract: Nuclear reactor with a radiation-emitting core including a container for conducting a coolant, the radiation-emitting container having a wall formed with a plurality of slots disposed parallel to one another, the slots having a depth within the wall equal to at least one-fourth the thickness of the wall, the slots being spaced from one another a distance which is at most as great as the depth thereof.

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.

Abstract: A pressurized-water reactor pressure vessel has a plurality of inlet openings through which coolant is introduced from the cold legs of a plurality of main coolant loops, into an annular descent space of restricted radial extent and formed between the inside of the vessel's side wall and the outside of a core barrel on the inside of the vessel. To prevent outward loss of coolant from the vessel in the event of a break in any of the cold legs, the vessel is internally provided with a check valve assembly for each of the inlet openings, and to avoid restriction of the normal inlet coolant flow rate, each assembly comprises a plurality or series of flap valves which are each individually of small dimensions so that they can be fitted into the descent space. Therefore, these flap valves are normally held open by the inlet coolant flow but can snap shut to outward coolant flow.