Abstract: A fuel assembly for a boiling water reactor has a plurality of fuel rods which are mounted in a plurality of spacers disposed at a spacing distance from each other in the axial direction of the fuel element. At least one of the fuel rods has a reduced length. Deflection elements are arranged at least in the upper region of the fuel element in order to improve the dry-out behavior of the assembly. The fuel assembly further includes measures that reduce a loss of pressure caused in the upper region by the deflecting elements so as to improve thermo-hydraulic stability and the shutdown behavior.

Abstract: In a boiling water fuel assembly, some of the fuel rods are shortened. It is necessary to establish a sufficiently high maximum power for transition to boiling. To optimize this power, spacers are at a constant distance at a bottom and are at a shorter distance at a top. The spacers belonging to upper group have turbulence-generating vanes which, however, do not project above the shortened fuel rods.

Abstract: A boiling water reactor includes fuel assemblies having a case containing fuel rods which are parallel to walls of the case. Flow subchannels are formed by each four of the fuel rods. At least two and preferably four vanes in the flow subchannels are tapered in a vertical coolant flow direction and are three-dimensionally curved in such a way as to generate a swirl in the coolant flow. It is therefore possible to obtain a relatively high output from the fuel assembly.

Abstract: A fuel assembly for a boiling water reactor includes an elongated fuel assembly case, mutually parallel fuel rods having longitudinal axes and being disposed in the case, and longitudinally extending inner walls having lateral surfaces facing toward the fuel rods. At least some of the lateral surfaces have grooves formed therein extending perpendicular to the longitudinal axes of the fuel rods. A boiling water reactor includes a boiling water circuit having a pressure vessel and a steam turbine. A plurality of the fuel assemblies are disposed mutually parallel in the pressure vessel. The fuel rods are bathed by boiling water flowing around them in the longitudinal direction of the fuel rods.