Patent Number: 063339579
Section: description

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, particularly to FIG. 1, there is illustrated a schematic representation of a nuclear fuel bundle generally designated 10 comprised of a lower tie plate 12, a pair of water rod assemblies 14 and 15 secured at their lower ends to the tie plate 12, spacers 16 secured to the water rod assemblies 14 and 15 at spaced positions therealong and fuel rods 18 received through openings in the spacers 16 and secured to the lower tie plate 12. Water assemblies 14 and 15 each have threaded lower end plugs 19 for threaded reception in complementary threaded openings in the tie plate 12. The water rod assemblies 14 and 15 are each comprised of essentially two sections, lower water rods 20, 21, respectively, and tie bars 22 and 24. The water rods 20 and 21 and the tie bars 22 and 24 are secured to one another in a length adjustable manner such that the lengths of the water rod assemblies lie within a predetermined range, i.e., on the order of 0.040 inches. As also noted, the adjustment in length of each water rod assembly requires particularly shaped parts, for example, a threaded washer 40 in FIG. 2 having a pair of opposite flats, and upper ends of the tie bars 22 and 24 having heads 26 and 28 which are in a D-shaped configuration. While the D-shaped configuration is used herein as a representative example of the shape of the upper end heads of the tie bars, it will be appreciated that other non-circular shapes, for example, multiple flats, can be employed. Additionally, one of the water rod assemblies is a tabbed rod configuration. For example, the water rod assembly 14 has radially projecting tabs 30 for engaging above and below the various spacers. The other water rod assembly 15 is an untabbed assembly. Releasable locking subassemblies, generally indicated 23 in FIGS. 1 and 2, are provided for respectively securing the tie bars and water rods to one another forming joints therebetween. Referring to FIGS. 1 and 2, the lower end of each tie bar 22 and 24 is threaded and has an axially extending slot 51 in FIG. 5 extending along one side. The upper end of the water rod 20 has an end plug 32 complementarily threaded to the lower end of the tie bar 22. The upper end of the end plug 32 includes a plurality of equally spaced, radially extending slots 34, illustrated in part in FIG. 2. At the lower end of the tie bar 22, there is provided a sleeve cap 36 having a radially extending slot 38. Between the end plug 32 and sleeve cap 36, there is provided a threaded washer 40 and a pair of lock washers 42 and 44. Lock washer 42 has a raised axially projecting portion 46, e.g., a tab, along a radius thereof while lock washer 44 similarly has a raised axially projecting portion 48. Each lock washer has a radially inwardly extending projection or tab 49 for engaging along a slot 51 formed in the lower threaded end of the tie bar 22, as illustrated in FIG. 5. The threaded washer 40 threads on the lower threaded end of the tie bar while the lock washers are unthreaded. It will be appreciated that by threading the tie bar into and out of the end plug 32, the length of the water rod assembly can be adjusted. For example, to shorten the water rod assembly, the, threaded washer 40 is first rotated upwardly sufficiently to remove the lower axially projecting portion 46 of the lock washer 42 from engagement in one of the slots 34 of the end plug 32. The tie bar can then be screwed into the upper water rod end plug and the threaded washer rotated to again bear against the lower lock washer with the tab 46, in one of slots 34. To lengthen the water rod assembly, the reverse procedure is utilized. Referring to FIG. 4, it will be appreciated that the head at the upper end of each tie bar has a D-flat configuration, i.e., the flat appearing at 50. Similarly, the lock washer 40 has a D-flat configuration. As noted previously, to adjust the length of the tabbed water rod assembly 14, the water rod 20 must be within one turn of bottoming out on the lower tie plate 12 and the tabs 30 and D-flat orientation must be maintained in a predetermined direction. A tool kit is provided in accordance with the present invention to effect the adjustment in length of the water rod assemblies and to verify and maintain the correct orientation of the assemblies after fabrication and during handling. To accomplish this, there is provided a tool kit comprised of a wrench for applying to the threaded washer (FIG. 6), a socket (FIGS. 7-9), orientator wrenches (FIG. 10), orientator gauges (FIGS. 11-14), and an orientator cap (FIGS. 15-17). Referring to FIG. 6, there is illustrated the threaded washer wrench 60 for engaging about the threaded washer 40 of the releasable locking subassembly 23 in FIG. 2. It will be appreciated from a review of FIG. 6 that the threaded washer 40 has a pair of flats 62 and 64 on opposite sides thereof. The threaded washer wrench 60 includes a head 66 having a pair of jaws 68 and 70 opposite one another defining an opening therebetween with opposed parallel surfaces 69 and a base 72 along the side of the opening. Significantly, the juncture between each of the jaws 68 and 70 and the base 72 is provided with a relief 74. The purpose of the relief is to prevent the rounding off of the corners of the juncture of the flats 62 and 64 and the arcuate areas of the threaded washer 40 between those flats. The wrench 60 also includes an elongated handle 76. Referring now to FIGS. 7-9, the socket 80 includes a generally cylindrical socket body 82 having a recess 84 opening through one end of the body. As illustrated in FIG. 9, the recess 84 has a cross-sectional shape generally complementary to the cross-sectional shape of the heads 26 and 28 at the upper ends of the tie bars 22 and 24. As illustrated, the heads 26 and 28 have a single flat. Accordingly, the recess 84 of the socket 80 has a corresponding flat 86. On the opposite end of the socket body 82 in FIG. 9 is a socket head 87 having an aperture 88. The socket head 87 and socket body 82 are suitably secured to one another. The aperture 88 is preferably multi-sided, e.g., in this instance, square, to receive a complementary-shaped shank of a tool driver. Thus, with the socket 80 applied over the heads 26 and 28, the tool driver when engaged in the square opening 88, can rotate the tie bars. Referring to FIG. 10, there is illustrated a pair of orientator wrenches 90 and 92. Each wrench has an opening 94 adjacent an enlarged head 96 at one end of the wrench whereby the wrench can be applied to the heads 26 and 28 of the tie bars. Additionally, each head has a witness notch 98. The witness notch is generally a V-shaped notch formed in the middle of the wrench head 96. The wrenches 90 and 92 are utilized in maintaining the D-flats on the heads of the tie bars in proper orientation. By aligning the wrenches generally parallel to one another and aligning the witness notches 98 with one another, it will be appreciated that the D-flats are located on predetermined sides of the wrenches in a generally common plane as illustrated in FIG. 10. Referring now to FIGS. 11-14, there are provided orientator gauges 100a, b and c (FIG. 14). Each gauge 100a, b or c comprises a gauge body 101 having a pair of openings 102 and 104. The gauges are similar to one another with the exception that the openings 102 and 104 of one gauge are reduced in size relative to the size of the openings of the other gauges. In a preferred embodiment of the present invention, there are provided three gauges wherein the size of the openings 102 and 104 are progressively reduced from a maximum to a nominal and then to a minimum size, respectively. The openings 102 and 104 in each gauge are, however, identical in orientation relative to one another, i.e., the D-flats 106 and 108 lie in a common plane. The gauge openings 102 and 104 are spaced one from the other corresponding to the spacing between the tie bars 22 and 24. The openings are also shaped complementary to the shapes of the heads 26 and 28 of the tie bar. In a preferred embodiment, it will be appreciated that the openings 102 and 104 have single flats 106 and 108, respectively, aligned with one another as illustrated in FIG. 11, i.e., in a common plane. As best illustrated in FIG. 12, the openings have axes parallel to one another. However, the body of each gauge 100a, b and c is stepped at 110 such that the margin 112 defining the entrance to opening 102 is axially offset from the margin 114 defining the entrance to the opening 104. Each of the maximum, nominal and minimum gauges 100a, 100b and 100c, respectively (FIG. 14), are applied in sequence to the heads 26 and 28 of the tie bars 22 and 24 in FIG. 13. Thus, once the heads of the tie bars are oriented by the orientator wrenches illustrated in FIG. 10, gauges 100a, 100b and 100c are sequentially applied to the heads to orient the heads within predetermined tolerances. For example, the maximum orientator gauge 100a is first applied to the heads 26 and 28 in FIG. 13. If the heads are not properly oriented, the gauge is applied such that opening 102 engages one of the heads. The engaged head and hence the associated tie bar can then be displaced or rotated a very limited distance about the axis of the engaged tie bar such that the adjoining head can be disposed in the opening 104. That is, with the head in the opening 102, and the head of the adjoining tie bar spaced from the margin 114 of opening 104, the gauge can be displaced, i.e., rotated, to ensure alignment of the opening 104 with the head of the adjacent tie bar followed by the insertion of both heads through the openings. Upon removal of the maximum gauge 100a, a nominal gauge 100b can be applied similarly to the heads followed by a similarly applied minimum gauge 100c. Gauge 100c provides the desired orientation of the heads. With the water rod assemblies in the desired orientation and adjusted length, the fuel bundle is ready for shipment. It will be appreciated that use of one of the gauges 100a, 100b or 100c could be omitted or that additional gauges of different sizes can be used. To ensure that the orientation is maintained during shipment, an orientation cap 118 (FIGS. 15-17) is provided. The orientation cap has a cap body 119 including a pair of openings 120 and 122 through one side of the body. The openings 120 and 122 correspond in shape to the shape of the heads 26 and 28 of the tie bars 22 and 24, i.e., they have a D-flat orientation. With the cap 118 inserted onto the heads of the tie bars, it will be appreciated that the tie bars are prevented from rotation, for example, during shipping. The cap 118 is also provided with a central threaded opening 124 for securing the cap to the fuel bundle or to assist in the removal of the orientating cap from the tie bar heads 26 and 28. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.