Nuclear fuel assembly spacer and loop spring with enhanced flexibility

This patent describes a fuel bundle having a surrounding channel, and upper tie plat, a lower tie plate, fuel rods and a pari of water rods, wherein the fuel rods are arranged in a matrix and positioned in parallel upstanding relation to one another between the upper and lower tie plates, the pair of water rods are arranged side-by-side and positioned centrally of the fuel bundle such that the water rod pair occupies seven matrix positions centrally of the matrix, the pair including a first water rod occupying a first three positions in the matrix and part of a forth position, the second water rod of the water rod pair occupying a second three positions in the matrix and part of the fourth position, a system for the securing of the paired water rods comprising in combination: first and second U-shaped spacers, each spacer having a portion that extends between the water rods, each portion bearing against each water rod to maintain the water rods in spaced relationships; and means for biasing the water rods against the U-shaped spacers