Patent Number: 046876316
Section: abstract

A reusable fastener device includes an attachment nut and a retainer housing mounted to the adapter plate of the fuel assembly top nozzle and removable with the top nozzle upon reconstitution of the fuel assembly. The attachment nut has a central tubular stem and upper and lower flanges connected to and extending radially outwardly from opposite ends of the stem. The stem is internally threaded for mating with the threaded upper end plug extension of the strucutural member. The upper flange of the nut has a conical-shaped lower surface and a periphery adapted for engagement in order to rotate the nut for threading onto and unthreading from the structural member extension between fastened and unfastened positions. The lower flange of the nut is in the form of a plurality of radial segments extending outwardly from the stem and angularly spaced from one another so as to define a plurality of cutouts therebetween which alternate with the segments. The retainer housing has a tubular hollow body and a plurality of upper sectors and lower tabs connected to and extending respectively radially inwardly and outwardly from opposite ends of the tubular body. The upper sectors are angularly spaced from one another so as to define a plurality of openings sized to receive the radial segments of the nut therethrough. Also, the upper sectors extend radially inwardly from the tubular body so as to define a central opening sized to receive the central stem of the nut and to define an interrupted conical-shaped upper surface surrounding the central opening which matches the conical-shaped lower surface on the upper flange of the nut. The lower tabs rest upon and are rigidly connected to the top nozzle adapter plate so as to align the central opening of the retainer housing with the hole through the adapter plate and dispose the upper sectors in a location spaced from the adapter plate at which their interrupted conical-shaped upper surface will be contacted by the conical-shaped lower surface of the upper flange of the nut when the central stem thereof is threaded onto the upper end extension of the structural member to the fastened position. The upper sectors are yieldably deflectible upon being contacted by the upper flange of the nut such that inner edges of the upper sectors engage the central stem of the nut so as to rotationally lock the lower flange of the nut to the adapter plate when the nut is rotated to its fastened position. Finally, the retainer housing also includes auxiliary tabs attached to the upper sectors and being bendable between open and closed positions for respectively allowing and preventing passage of the lower segments of the nut through the openings defined between the upper sectors of the retainer housing.