Abstract: In a fuel element for a pressurized-water reactor, in addition to spacers, flow-guiding structural parts are arranged. The flow guiding parts include four outer webs which, in a plane oriented perpendicularly to the central longitudinal axis, surround a square inner region of which the center point lies on the central longitudinal axis. At their lower longitudinal side facing the flowing cooling water in the operating state, the outer webs are provided with deflection lugs pointing towards the inner region and are structurally identical, wherein mutually opposite outer webs are arranged mirror-symmetrically with respect to a center plane extending in the axial direction. Such a structural part forms, at most for a number of fuel rods which is smaller than their total number in the fuel element, cells through which a respective fuel rod is guided. The number of these cells, which are situated in a row or column, is smaller than the number of the fuel rods respectively situated in this row or column.

Abstract: In a computer modeling method for the core of a nuclear reactor the core is divided into a plurality of primary grids in the form of coarse mesh cells. A sub-section of the core relating to at least one grid is assigned to that grid. The sub-section includes that grid and a buffer zone that surrounds the grid horizontally and contains at least the grid that lies immediately adjacent to the first grid. The sub-section is sub-divided into a plurality of secondary grids—fine mesh cells—that are smaller than the primary grids. In a first computing step, a model of the core is calculated using a nodal calculation method, based on a respective dataset that is assigned to each primary grid. In a second computing step, a respective second dataset is assigned to each secondary grid of a sub-section and a model is then calculated for the sub-section, based on the dataset and the flows on the border of the sub-section that have been calculated in the first computing step.

Abstract: In a computer modeling method for the core of a nuclear reactor the core is divided into a plurality of primary grids in the form of coarse mesh cells. A sub-section of the core relating to at least one grid is assigned to that grid. The sub-section includes that grid and a buffer zone that surrounds the grid horizontally and contains at least the grid that lies immediately adjacent to the first grid. The sub-section is sub-divided into a plurality of secondary grids—fine mesh cells—that are smaller than the primary grids. In a first computing step, a model of the core is calculated using a nodal calculation method, based on a respective dataset that is assigned to each primary grid. In a second computing step, a respective second dataset is assigned to each secondary grid of a sub-section and a model is then calculated for the sub-section, based on the dataset and the flows on the border of the sub-section that have been calculated in the first computing step.

Abstract: A pressurized water nuclear reactor includes a reactor core, a nuclear reactor fuel assembly disposed in the reactor core, a fuel rod disposed in the fuel assembly, and a nuclear fuel column disposed in the fuel rod being enriched to a variable extent with fissionable nuclei over the length thereof. The reactor core has an inlet for liquid water acting as coolant closest one end of the fuel rod and of the fuel assembly and an outlet for the liquid water closest to the other end of the fuel rod and of the fuel assembly. A steam generator has a primary tube connected to the inlet and the outlet. One half of the nuclear fuel column at the outlet having an average enrichment being less than the average enrichment of the other half of the fuel column, and/or the nuclear fuel column having a depletion zone with an average enrichment being less than the average enrichment over the entire length of the column.