Fuel assembly for a pressurized-water nuclear reactor
A fuel element for a pressurized water reactor has fuel rods guided through a number of axially spaced spacers. The spacers form a square grid with mesh openings arranged in rows and columns. Support tubes that do not contain fuel pass through a number of the mesh holes and are joined to the meshes . The support tubes are spread out in positions within the grid with a predetermined number of support tubes and a distribution thereof within the grid, which is rotationally symmetric about 90° with regard to a rotation about the central axis of the spacer, the central axis is perpendicular to the grid plane, the number of rows and columns that do not contain any support tubes is minimal. Optionally, remaining inner rows and columns that do not contain any support tubes are not situated next to one another.
1. A fuel assembly for a pressurized-water nuclear reactor, comprising:
a multiplicity of fuel rods;
a plurality of spacers mutually spaced-apart axially along said fuel rods, each of said spacers substantially defining a grid plane and forming a square grid with a multiplicity of meshes arranged in rows and columns, said rows including inner rows and said columns including inner columns;
a plurality of support tubes respectively guided through said meshes and cohesively joined to said spacers at said meshes, said support tubes not containing fuel;
said support tubes being distributed to positions in said grid such that, with a given number of support tubes in said grid, a distribution of said support tubes in said grid does not vary upon a rotation of said grid through 90° about a center axis extending perpendicular to said grid plane of said spacer; and
wherein no inner rows and inner columns without said support tubes adjoin one another;
the number of rows having no said support tubes being minimal and the number of columns having no said support tubes being minimal.
2. The fuel assembly according to claim 1 , wherein, with a predetermined number of support tubes and meshes, said support tubes are distributed in said grid to form rows and columns without said support tubes exclusively at a margin of said spacer.
3. The fuel assembly according to claim 1 , wherein at least one of said rows and said columns without a control rod guide tube is provided with at least one structure tube.
4. The fuel assembly according to claim 1 , wherein at least one of said spacers has a stiffness of less than 10 kN/mm.
5. The fuel element according to claim 4 , wherein said at least one spacer has a stiffness of between 5 and 7 kN/mm.