Abstract: A method for production of spacers to hold at least a number of elongated fuel rods (5) in a fuel unit (20) for placement in a re-actor (1) is described. The method comprises the steps of providing at least two spacers (30), to provide a set of mandrels (40) comprising a number of mandrels (42), to arrange at least two spacers (30) with one on top of the other on the set of mandrels (40), and to heat treat the spacers (30) when they are arranged on the set of mandrels (40) so that the cells (31) in the spacers (30) adapts to the mandrels (42).

Abstract: The present invention relates to a fuel assembly for a light-water nuclear reactor with a substantially square cross section which comprises fuel rods (4) extending between a bottom tie plate (16) and a top tie plate (17). A coolant is adapted, during operation, to flow upwards through the fuel assembly. According to one aspect of the invention, the fuel assembly comprises a plurality of fuel units (3) stacked on top of each other, wherein each fuel unit (3) comprises a plurality of fuel rods (4) extending between a top tie plate (17) and a bottom tie plate (16). The fuel units are arranged attached to a support structure (4a, 14, 14a, 14b) extending through the whole fuel assembly such that axial gaps are formed between the fuel units (3). One of the tie plates is freely movable relative to the support structure.