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: For the redistribution of a coolant flow from a first region into a second region, in particular in boiling-water-reactor fuel elements having an eccentrically disposed water passage, a fuel-rod bundle is constructed in a mirror symmetry manner relative to a diagonal. A distance between adjacent fuel rods increases monotonically in particular along a diagonal. In addition, a fuel-rod bundle as an entity may be offset eccentrically along the diagonal. To compensate for asymmetry in the reactor core, a redistribution of coolant is provided which is advantageous in pressurized-water-reactor fuel elements.

Abstract: A transiently unstable state of a boiling-water reactor is damped by measuring the oscillating neutron flux and, after a first threshold value is exceeded over a plurality of oscillation periods, the rate of increase of the oscillation is determined. Depending on the slope of the increase, and after a further threshold value (in particular one dependent on the rate of increase) for the oscillating flux is exceeded, a selection is made which one of various stabilization strategies for damping the oscillation should be triggered before a SCRAM becomes necessary. A hierarchy of stabilization strategies is available: blocking a power increase, for instance, in the control system, controlled slow reduction of the power, or rapid power reduction by a "partial SCRAM". The monitoring of the unstable state is effected with a system of sensors strategically distributed throughout the core and which redundantly measure the flux in one region of the core.

Abstract: A transiently unstable state of a boiling-water reactor is damped by measuring the oscillating neutron flux and, after a first threshold value is exceeded over a plurality of oscillation periods, the rate of increase of the oscillation is determined. Depending on the slope of the increase, and after a further threshold value (in particular one dependent on the rate of increase) for the oscillating flux is exceeded, a selection is made which one of various stabilization strategies for damping the oscillation should be triggered before a SCRAM becomes necessary. A hierarchy of stabilization strategies is available: blocking a power increase, for instance, in the control system, controlled slow reduction of the power, or rapid power reduction by a "partial SCRAM". The monitoring of the unstable state is effected with a system of sensors strategically distributed throughout the core and which redundantly measure the flux in one region of the core.

Abstract: A transiently unstable state of a boiling-water reactor is damped by measuring the oscillating neutron flux and, after a first threshold value is exceeded over a plurality of oscillation periods, the rate of increase of the oscillation is determined. Depending on the slope of the increase, and after a further threshold value (in particular one dependent on the rate of increase) for the oscillating flux is exceeded, a selection is made which one of various stabilization strategies for damping the oscillation should be triggered before a SCRAM becomes necessary. A hierarchy of stabilization strategies is available: blocking a power increase, for instance, in the control system, controlled slow reduction of the power, or rapid power reduction by a "partial SCRAM". The monitoring of the unstable state is effected with a system of sensors strategically distributed throughout the core and which redundantly measure the flux in one region of the core.