Patent Number: 053295714
Section: abstract

A reactor core for a boiling water nuclear reactor comprises a plurality of vertical fuel assemblies (40a, 42, 44), each one containing a plurality of fuel rods (10), which are arranged between a bottom-tie plate (11) and a top-tie plate (12) in a surrounding vertical casing (6) and which extend through a number of spacers (13, 13a-f) which are arranged in spaced relationship in the vertical direction and which together with the bottom-tie plate and the top-tie plate retain the fuel rods in spaced relationship in the lateral direction. Each fuel assembly is designed with an inlet (3) for water for conducting water in through the bottom-tie plate, through the space between the fuel rods in the vertical casing, and out through the top-tie plate. Some of the fuel assemblies, at a level located above the center of the active length of the fuel rods and below at least two of the uppermost spacers (13a, 13b), are provided with outlet holes (41, 43, 44) for release of water from the space between the fuel rods to vertically directed spaces (32, 37a, 37b), arranged outside the fuel assembly and traversed by water, or to a vertically directed channel (45), arranged internally in the fuel assembly and traversed by water.