Nuclear fuel rod assembly - with offset spacer grids esp for fast neutron reactors

摘要

Each of the horizontal spacer grids of offset from a truly symmetrical position by a distance of ca. 1 mm., alternate grids from top of bottom of the assembly being offset in opposite directions so that the rods have a very slight vertical undulation. Esp. the grids are hexagonal meshed, each mesh having 3 symmetrical inner lugs of which 2 are in contact with the fuel rod under normal conditions. Due to the permanent sets, distortion due to heating etc. is along predetermined directions so simplifying tolerance calculations.