OPTIMIZED FLOWER TUBES AND OPTIMIZED ADVANCED GRID CONFIGURATIONS

摘要

The present invention is directed to a support grid 26 for a nuclear fuel assembly 20 having a generally cylindrical fuel rod 28 having a diameter and wherein the support grid 26 includes a plurality of outer straps 44, And a frame assembly 40 having a member 50 and / or a spiral frame member 70. The tubular member 50 / helical frame member 70 has contact portions 54 and 55 structured to contact adjacent helical frame members 70 and at least one helical fuel rod contact portion 52 having a smaller diameter. The smaller diameter generally corresponds to the diameter of the fuel rod 28 so that the fuel rod on which the helical frame member 70 is disposed can engage the inner helical frame member 70 at the helical fuel rod contact 52. The helical fuel rod contact portion 52 may have a variable pitch.