Patent Number: 
Section: claims

1. A spacer grid, comprising:a plurality of strips forming a plurality of grid cells;a plurality of fuel rods;a plurality of springs supporting the fuel rods in predetermined directions on surfaces of the grid cells; anda plurality of mixing vanes, each of the mixing vanes protruding from an upper end of an inner surface of the grid cells toward a downstream direction of coolant,wherein the mixing vanes are arranged such that a pattern of mixing vanes within the left region of a vertical standard line is symmetrical to a pattern of the mixing vanes within the right region of the vertical standard line, and a pattern of the mixing vanes within the upper region of a horizontal standard line is symmetrical to a pattern of the mixing vanes within the lower region of the horizontal standard line,wherein the vertical standard line is defined by a vertical line passing through a centerpoint of the plurality of grid cells, and the horizontal standard line is defined by a horizontal line passing through said centerpoint, andwherein a pattern of the mixing vanes arranged on the vertical standard line is the same as the pattern of the mixing vanes within the left region of the vertical standard line, and a pattern of the mixing vanes arranged on the horizontal standard line is the same as the pattern of the mixing vanes within the lower region of the horizontal standard line.