Patent Number: 052710491
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, it is seen in FIG. 1-3 that the invention is generally indicated by the numeral 10. Grid key 10 is formed in the shape of a rectangular bar to provide a main body portion 12 having first and second ends 14, 16. Main body portion 12 is bent near the middle to form an approximate 90 degree angle in main body portion 12. First end 14 is provided with two wings or tabs 18. In the preferred embodiment tabs 18 are integral with main body portion 12 for ease of fabrication and strength. The following terms will be used for the sake of clarity in referring to the various dimensions of main body portion 12 and tabs 18. The dimension of main body portion 12 between first and second ends 14, 16 shall be indicated as the length of main body portion 12. The dimension of tabs 18 from first end 14 back toward the bend in main body portion 12 shall be indicated as the length of tabs 18. The dimension across both tabs 18 shall be indicated as the width across tabs 18 with the corresponding dimension across main body portion 12 being indicated as the width of main body portion 12. The thickness of tabs 18 and main body portion 12 is that dimension perpendicular to the width. Solid lines are used in FIG. 2,3,5, and 6 to clearly distinguish between main body portion 12, tabs 18, and thickened section 20 of main body portion 12. As best seen in FIG. 2-4, tabs 18 extend outward in opposite directions from the width of first end 14 and along a portion of the length of main body portion 12. Although the length of tabs 18 will depend on the type of grid to be keyed, the length of tabs 18 in the preferred embodiment is 0.400 inch +/-0.010 inch when used for zircaloy or inconel grids. As best seen in FIG. 4, one side of tabs 18 is flush with main body portion 12 while the opposing side of tabs 18 tapers inwardly toward main body portion 12 at approximately a 45 degree angle. It is also seen in FIG. 2 and 4 that main body portion 12 is provided with thickened section 20 that is thicker than the remainder of main body portion 12 and has a length equal to that of tabs 18. During loading of fuel rods into the interior grid cells of the fuel assembly, grid key 10 is used in the following manner. Grid key 10 is positioned in interior grid cell 22 as seen in FIG. 5 so that first end 14 is adjacent soft stops 24. A separate tool is then used to press thickened section 20 against soft stops 24 as seen in FIG. 1 and 6 and wedge first end 14 in place. Tabs 18 restrict the installation depth of thickened section 20. FIG. 1 is a cutaway view of a grid assembly 26 that illustrates grid key 10 when in its operative position. Second end 16 is above grid assembly 26 and extends away from cell 22 being keyed at approximately a 45 degree angle. After a fuel rod is loaded into cell 22, grid key 10 is removed by using second end 16 as a lever to twist or pivot thickened section 20 out of its wedge position between soft stops 24. Because many varying and differing embodiments may be made within the scope of the inventive concept herein taught and because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.