Distance lattice for fuel rod assembly in nuclear reactor

A grid for a nuclear fuel rod assembly, the grid comprising:

• a plurality of perpendicularly flat plates, the flat plates forming substantially square cells;
• a plurality of deflectors formed integrally with the flat plates, wherein each deflector is oriented at an angle to a longitudinal axis of the grid, and wherein each cell has at least two opposing deflectors;
• each cell having an insertable spacer having a substantially octagonal shape that is [s]ymmetric about a center axis of the cell, the insertable spacer having a constant height along its perimeter, and a uniform cross-section along its height, the insertable spacer having a closed contour in a cross-sectional view, the insertable spacer formed of four convex surfaces and four concave surfaces, the four concave surfaces being in contact with the corresponding flat plates, and the four convex surfaces each having a flat portion for fixing a corresponding fuel rod and which is flat prior to insertion of the fuel rods,
• wherein opposite longitudinal surfaces of the insertable spacer are parallel to each other.