nuclear fuel rod 10 is charged alternatively in consideration of the rigidity of each support 42 the contact portion 43 may protrude toward each dual cooling nuclear fuel rod 10 in a convex shape or in a simple plane shape the support structure 40 is obtained by performing punching and plastic working on a rectangular sheet using a press machine etc so as to form the slits 41 and the supports 42 having the contact portion 43 and the connector portions 44 and then by bending the rectangular sheet into a quadrilateral prism fig1 illustrates an example in which the first grid strap 20 the second grid strap 30 and the support structure 40 are assembled into the spacer grid 1 of the present invention as illustrated in fig1 the second grid strap 30 is assembled to the first grid strap 20 from the top to the bottom such that the second grid slits 31 of the second grid strap 30 are coupled to the first grid slits 21 of the first grid strap 20 then the first and second grid straps 20 and 30 are attached to each other around the intersections thereof by for instance welding then the support structure 40 is fitted into the first and second grid straps 20 and 30 from the top to the bottom such that the slits 41 in the corners of the support structure 40 are.