Patent Number: 040594831
Section: claims

1. In a nuclear reactor fuel assembly, the fuel assembly including a plurality of zircaloy spacer grids which locate and support elongated fuel elements which pass therethrough, said fuel assembly further including a plurality of guide tubes which extend through the fuel assembly parallelly of the fuel elements and which receive movable neutron absorber elements, the improvement comprising: at least a first seismic grid positioned intermediate a pair of spacer grids, said seismic grid having a greater resistance to deformation when compared to the spacer grids and having larger external dimensions than said spacer grids, said seismic grid including:  a central portion, said central portion having said openings and projections formed therein; and  oppositely disposed edge portions, said edge portions being bent inwardly toward the fuel assembly at an angle of less than .  tube segments mounted in said seismic grid so as to be in alignment with the fuel assembly guide tubes, said tube segments having inner diameters greater than the outer diameters of aligned guide tubes;  means joining divider members which intersect said tube segments to said tube segments; and  means attaching said tube segments to the exterior of said guide tubes.  tube segments mounted in aid seismic grid so as to be in alignment with the fuel assembly guide tubes, said tube segments having inner diameters greater than the outer diameters of aligned guide tubes;  means joining divider members which intersect said tube segments to said tube segments; and  means attaching said tube segments to the exterior of said guide tubes.  tube segments mounted in aid seismic grid so as to be in alignment with the fuel assembly guide tubes, said tube segments having inner diameters greater than the outer diameters of aligned guide tubes;  means joining divider members which intersect said tube segments to said tube segments; and  means attaching said tube segments to the exterior of said guide tubes. 2. The apparatus of claim 1 wherein said divider member define grid sectors which each receive a plurality of fuel elements. 3. The apparatus of claim 1 wherein said perimeter strip openings are generally aligned with fuel elements disposed adjacent to said perimeter strip in the outer row of grid sectors defined by said perimeter strip and divider members. 4. The apparatus of claim 3 wherein said perimeter strip projections comprise inwardly extending dimples formed in said perimeter strip, said dimples being located above and below each of said openings. 5. The apparatus of claim 4 wherein said divider members are provided with projections extending into each of said grid sectors so as to limit motions of the fuel elements passing therethrough. 6. The apparatus of claim 5 wherein said divider member define grid sectors which each receive a plurality of fuel elements. 7. The apparatus of claim 1 wherein said perimeter strip comprises: 8. The apparatus of claim 6 wherein said perimeter strip openings are generally aligned with fuel elements disposed adjacent to said perimeter strip in the outer row of grid sectors defined by said perimeter strip and divider members. 9. The apparatus of claim 8 wherein said perimeter strip projections comprise inwardly extending dimples formed in said perimeter strip, said dimples being located above and below each of said openings. 10. The apparatus of claim 9 wherein said divider member define grid sectors which each receive a plurality of fuel elements. 11. The apparatus of claim 10 wherein said perimeter strip edge portions are serrated. 12. The apparatus of claim 1 wherein said means attaching divider members to guide tubes comprises: 13. The apparatus of claim 6 wherein said means attaching divider members to guide tubes comprises: 14. The apparatus of claim 11 wherein said means attaching divider members to guide tubes comprises: