Patent Number: 053612833
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, it is seen in FIG. 1 that the invention is generally indicated by the numeral 10. Locking arrangement 10 is integral to the guide tube assembly 12 and is designed to be reusable without the release of loose parts in the system. Locking arrangement 10 is generally comprised of a retainer sleeve 16 that cooperates with slots 18 in upper end fitting 14 to lock the guide tube assembly and upper end fitting together in their installed position. As seen in FIG. 4, retainer sleeve 16 is formed from a cylindrical tube that is provided with a plurality of flexible curved tabs 20 that extend outwardly and are spaced apart around the circumference of the tube substantially at the mid section of the tube. Tabs 20 are curved in the preferred embodiment as seen in FIG. 5 to provide for smoother operation. Tabs 22, which are optional, are located at the lower end of the tube and spaced around the circumference. Tabs 22 serve to center guide tube assembly 12 in the bore through upper end fitting 14 and provide a more rigid connection. Tabs 20 serve to retain guide tube 12 assembly and upper end fitting 14 in their installed position relative to each other. In the installed position, tabs 20 extend outwardly immediately above shoulder 24 defined at the lower end of each slot 18. This prevents upper end fitting 14 from being removed from guide tube assembly 12. As seen in FIGS. 1 and 2, upper end fitting 14 is provided with four vertically extending slots 18 that are spaced apart around bore 26 but do not extend the entire length of the bore. In order to provide the necessary resilient biasing action, retainer sleeve 16 is preferably made from a material that is used for springs and suitable for use in a nuclear application, such as nickel alloy 718. As seen in FIG. 1, guide tube assembly 12 is provided with an upper end sleeve 28 that serves as an attachment point for retainer sleeve 16. Upper end sleeve 28 may be attached to guide tube assembly 12 by any suitable means such as welding as indicated by the numeral 29. As best seen in FIGS. 1, 3 and 4, the retainer sleeve 16 of the invention is attached to upper end sleeve 28 by the use of lugs or rigid tabs 30 that extend around a portion of the circumference of upper end sleeve 28. Retainer sleeve 16 is provided with slots 32 that are sized to receive tabs 30. To provide a permanent connection, retainer sleeve 16 may also be attached to upper end sleeve 28 by any suitable method such as bonding or welding. Since guide tubes are usually relatively thin (approximately 19 mils), an upper end sleeve is normally included on guide tubes to provide a point for attachment to the upper end fitting and to provide the necessary support for a shoulder stop 34 seen in FIG. 1 to prevent the upper end fitting from moving down the guide tube assembly when the fuel assembly is in the vertical position. During assembly, the upper end fitting 14 is pushed over upper end sleeve 28 and sleeve retainer 16. The tabs 20 and 22 are forced inboard as the end fitting slides over the guide tube assembly. When end fitting 14 is fully seated, a rotation tool not shown is received in tooling slots 34 on the upper end of retainer sleeve 16. The tool is used to rotate retainer sleeve 16 until tabs 20 spring outboard into slots 18 in upper end fitting 14. The presence of tabs 20 at shoulders 24 serve to retain upper end fitting 14 and guide tube assembly 12 in their relative installed positions. Tabs 22 maintain pressure against the walls of the bore 26 through end fitting 14 to retain guide tube assembly 12 in a centered position and provide for a more rigid connection. Removal of end fitting 14 is accomplished by engaging a rotating tool with tooling slots 34 and rotating retainer sleeve 16 approximately forty-five degrees to force tabs 20 inboard and then sliding end fitting 14 upward. As seen in FIG. 2, slots 18 are preferably semicircular to provide for ease of operation in forcing tabs 20 inboard during rotation of retainer sleeve 16. 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.