A method for optimally designing a spacer grid strap to support fuel rods of a nuclear fuel assembly and the spacer grid strap designed by the same are provided to implement uniform stress distribution by increasing a contact area between the fuel rod and a spring of the spacer grid strap. A method for optimally designing a spacer grid strap to support fuel rods of a nuclear fuel assembly includes the steps of: designing connection units between outer ends of upper and lower plates of the spacer grid strap and a spacer grid spring(S10); finding an unnecessary part of the spacer grid strap where stress is not distributed by applying values of the connection units between the upper and lower plates and the spacer grid spring(S20); designing an optimized shape of the spacer grid strap by deleting the unnecessary part(S30); and designing an optimized shape of the spacer gird spring(S40).
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