Abstract: A fuel assembly includes an array of fuel rods and guide thimbles disposed in laterally spaced relation to one another. The guide thimbles have upper ends extending above the upper ends of the fuel rods. The fuel assembly also includes a top nozzle defined solely by a flat rectangular adapter plate having a main central portion and a peripheral portion surrounding and merging with the main central portion. The main central portion of the adapter plate has a plurality of attachment holes receiving the upper ends of guide thimbles for attachment of the adapter plate upon the guide thimble upper ends in spaced relation above the fuel rod upper ends. A first sest of holes are defined through one pair of diagonal corners of the adapter plate for use in attaching sets of spring assemblies directly to and upon the adapter plate for alignment along the peripheral portions thereof.

Abstract: A hand held tool for removing a top nozzle from guide thimbles of a nuclear fuel assembly includes a handling assembly, a lower tool head, a coupling structure, and an actuating mechanism. The handling assembly includes an upper handle and an elongated handle pole attached to the upper handle and extending downwardly therefrom. The lower tool head includes an anchor assembly and a lift assembly. The anchor assembly has elongated probe members insertable into the guide thimbles and expansion sleeves thereon actuatable by the actuating mechanism between disengaged and engaged conditions with the guide thimble. The coupling structure couples both the lift assembly and anchor assembly to the lower end of the handle pole.

Abstract: A debris filter bottom nozzle in a fuel assembly has support structure in the form of four legs adapted to rest on a lower core plate of the nuclear reactor and a nozzle plate fixed one side of the four legs facing toward a lowermost grid of the fuel assembly. The nozzle plate has defined therethrough only a plurality of flow holes individually smaller in size than the maximum dimension of unoccupied spaces through the lowermost grid which allow flow of liquid coolant through the nozzle plate. Therefore, any debris being carried by the liquid coolant flowing through the bottom nozzle from the lower core plate to the fuel assembly which is small enough in size to pass through the flow holes will also pass through the unoccupied grid spaces, whereas any debris which is large enough to not pass through the unoccupied grid spaces and collect in the grid will not pass through the aperture plate flow holes.

Abstract: The invention relates to apparatus and a method for facilitating a scratchless insertion of a fuel rod into cellular grids of a nuclear fuel assembly.The apparatus comprises a thin-walled tubular member having an inner diameter substantially corresponding to the outer diameter of a fuel rod, and having a longitudinal slit formed in its wall so as to render the latter resiliently deflectable in a diameter-reducing sense. The method comprises the steps of mounting the thin-walled tubular member in position for protectively enveloping the fuel rod during insertion thereof; inserting the fuel rod into the grids while the tubular member is in place to envelope it; and withdrawing the tubular member from the inserted fuel rod.

Abstract: A reconstitutable control rod spider assembly includes a spider structure, control rods, and attachment joints for detachably fastening the control rods to the spider structure. Each attachment joint includes a connecting finger of the spider structure having a central bore extending therethrough and a pair of opposing flat segments formed on the interior thereof, and an elongated upper end plug of each control rod inserted through the finger bore and having a pair of opposing flat sectors formed on the exterior thereof beng interfitted with the opposing flat segments on the connectng finger to retain the control rod in a predetermined angular position relative to the finger. The upper end plug also has an externally-threaded portion formed on the exterior thereof above the flat sectors and being disposed above the connecting finger, and a pilot aligning portion formed on an outer terminal end thereof above the externally-threaded portion.

Abstract: A tool for straightening an arched pin into one of a pair of slots orthogonally defined in a screw head including an elongated rod-like member, means mounted on one end of the rod member for applying an axially directed force, an elongated sleeve mounting the rod-like member for reciprocal movement within the sleeve and having an end adapted to seat about the screw head, a tool handle mounted at one end of the sleeve adjacent the force applying means and a pin setting tool bit connected to an opposite end of the rod like member being indexible with one of the slots in the screw head and for delivering an impact force to the arched pin in the other screw head slot.

Abstract: The invention relates to apparatus and a method for facilitating a scratchless insertion of a fuel rod into cellular grids of a nuclear fuel assembly.The apparatus comprises a thin-walled tubular member having an inner diameter substantially corresponding to the outer diameter of a fuel rod, and having a longitudinal slit formed in its wall so as to render the latter resiliently deflectable in a diameter-reducing sense. The method comprises the steps of mounting the thin-walled tubular member in position for protectively enveloping the fuel rod during insertion thereof; inserting the fuel rod into the grids while the tubular member is in place to envelope it; and withdrawing the tubular member from the inserted fuel rod.

Abstract: In a reconstitutable nuclear fuel assembly, a top-nozzle-to-control-rod-guide-thimble attachment system employing a reusable locking tube having dimples. The guide thimble has longitudinal slots defining fingers therebetween. The fingers have rim (bulge) portions which engage a groove in the control rod passageway of the top nozzle adaptor plate for top-nozzle-to-guide-thimble attachment. The finger rim portions are prevented from moving radially inward, and thus leaving the groove, by a locking tube placed in the guide thimble. The locking tube has dimples at two elevations. The dimples interact with the other components of the attachment system to assure proper seating of the locking tube during locking tube installation and to assure against unintentional longitudinal movement of the locking tube during fuel assembly handling. An improperly seated locking tube complicates the underwater fuel assembly reconstitution operation.

Abstract: A fuel assembly skeleton includes a top nozzle, a number of longitudinally-extending guide thimbles having upper ends, a number of joints interconnecting the top nozzle and the upper ends of the guide thimbles. All but a few of the joints are structural joints providing rigid connections between all but a corresponding few of the guide thimble upper ends and the top nozzle. Each of the other few joints is a non-structural joint providing a non-rigid connection between a guide thimble upper end and the top nozzle. The number of structural joints constitutes at least a substantial majority of the joints and, in any event, the number is at least three times the number of non-structural joints. Each non-structural joint is composed of a hollow sleeve rigidly connected to the top nozzle and disposed in a slip fit relationship about the guide thimble upper end. The sleeve is bulge fitted in a passageway defined in the top nozzle.

Abstract: In a reconstitutable fuel assembly, a top nozzle attaching structure, which has an outer socket formed by a circumferential groove defined in the top nozzle adapter plate passageway wall and an inner socket formed by a circumferential bulge defined in the guide thimble upper end portion being capable of seating within the circumferential groove, incorporates an improved reusable tube disposable at a locking position for releasably locking the inner socket in locking engagement within the outer socket when the circumferential bulge is seated within the circumferential groove. The reusable locking tube includes an elongated hollow metal tubular body and at least a pair of small dimples preformed on the tubular body exterior prior to initial insertion of the locking tube to its locking position.

Abstract: A fixture for rectifying one of several different types of repairable and irreparable damage to the upper end portions, or insert sleeves, of the guide thimbles of a fuel assembly held in a work station includes a base having a plurality of tool positioning openings defined therein in a pattern matched with that of the guide thimbles and several aligning holes for mounting the base on guide members of the work station such that the tool positioning openings are disposed in alignment with the guide thimbles. Also, a plurality of different tools are selectively mountable in the openings of the base. Each tool is adapted to operate to rectify a different one of the types of repairable and irreparable damage to the insert sleeves of the guide thimbles.

Abstract: A cutter guide fixture for use in removing a top nozzle from the guide thimbles of a fuel assembly includes upper and lower plates coupled to one another for movement of the upper plate relative to the lower plate between upper and lower positions. The plates include aligned pairs of holes within which are mounted a plurality of cutters such that the cutting elements of the cutters are disposed in a common cutting plane. A pair of expansion locking pins are provided at a pair of diagonal corners of the lower plate for releasably attaching the fixture to the top nozzle and positioning the cutters in general alignment with a plurality of passageways defined in the adapter plate of the top nozzle and with a plurality of hollow upper end portions of the guide thimbles inserted and attached in the passageways.

Abstract: A fixture for removing a top nozzle of a reconstitutable fuel assembly held in a fixed position within a work station includes a pair of guide openings in two diagonally opposed corners of its base to movably mount the base on a pair of upstanding guide members of the work station and on the top nozzle in alignment therewith. Also, the fixture includes a pair of hollow expandable split sleeves with wedge pins inserted therein which are operable to lock the fixture to the top nozzle. An arrangement of drive and driven gears connected with a plurality of reaction pins mounted on the base of the fixture are operable to move the fixture base with the top nozzle thereto away from the guide thimbles of the fuel assembly and thereby cause the top nozzle adapter plate to release its connection with the guide thimbles.

Abstract: A fixture for inserting and removing locking tubes into and from locking positions in a top nozzle includes a lower traveling plate and an upper traveling plate disposed above the lower plate. The lower plate has hollow flexure tubes attached to and projecting downwardly therefrom. Each flexure tube has an axially segmented sleeve portion which terminates in a lower segmented rim, with the rim being expandable to a first outside diameter greater than an inside diameter of the locking tube and collapsible to a second outside diameter less than the inside diameter of the locking tube. The upper plate has actuating rods attached to and projecting downwardly therefrom through the flexure tubes.

Abstract: A method for reconstituting a nuclear reactor fuel assembly having its top nozzle adapter plate welded to its control rod guide thimble sleeves. Circumferentially cut the sleeves from the adapter plate below the weld. Separate the top nozzle from the cut sleeve 5. Obtain a modified top nozzle refashioned with a groove in its adapter plate control rod passageways. Insert the cut sleeves in the passageways of the modified top nozzle. Circumferentially bulge the sleeves into the grooves. A system for attachment of the top nozzle to the sleeves employing the above-described circumferential bulge and groove attachment.

Abstract: A tool for removing a locking tube from a locking position in the upper end portion of a guide thimble inserted within a passageway in a removable top nozzle of a reconstitutable fuel assembly includes an inner tubular member attached at its upper end to a bail assembly and at its lower end to a tubular extension having an expandable and collapsable lower end. Also, an actuatable shaft assembly of the tool is mounted for axial movement within the inner tubular member and lower tubular extension and has a conical nose disposed on its lower end which extends beyond a rim formed on the lower end of the tubular extension and an actuating knob coupled to its upper end. Rotation of the knob in one direction causes insertion of the conical nose into the lower end of the tubular extension and thereby increase in the circumference of the rim such that it will engage a lower edge of the locking tube when the tool is forced in an upward direction.

Abstract: A fixture for inserting locking tubes into locking positions in a top nozzle includes a tool guide with operable devices for locking the guide to the top nozzle such that openings in the guide are aligned above passageways in the adapter plate of the top nozzle. Resiliently deformable sleeves are disposed in the respective guide openings for retaining locking tubes stationarily therein. Each sleeve includes a lower internal ledge which a bottom edge of the locking tube disposed therein rests and an inside diameter smaller than the outside diameter of the locking tube such that the tube is mounted in a stationary position within the sleeve and an interference fit is maintained between the sleeve and the tube. Further, the fixture includes a tool holder mounting tube insertion tools each in the form of an elongated cylindrical plunger rod having a lower cylindrical portion of smaller diameter than an upper cylindrical portion such that a bottom shoulder is formed on the upper portion.

Abstract: A fixture for removing locking tubes from locking positions in a top nozzle includes a tool guide and a tool holder mounted above the tool guide for movement toward and away from the guide. Further, the fixture includes locking member removal tools each in the form of an outer elongated tubular member and an inner elongated actuating shaft. The tubular member is attached to the tool guide in alignment with one of its openings, while the actuating shaft is mounted to the tool holder and extends through the tubular member. When the tool guide is disposed on the top nozzle, both the tubular member and actuating shaft of each removal tool extend downwardly through one locking tube. The lower portion of the tubular member is in the form of a segmented sleeve having a lower segmented rim which is movable between circumferentially-collapsed and expanded positions. The actuating shaft of each tool has an upper cylindrical portion with an outside diameter larger than the inside diameter of the locking tube.

Abstract: A nuclear reactor fuel assembly having an improved attaching structure for removably mounting the top nozzle on the upper ends of the control rod guide thimbles. The attaching structure includes an outer socket defined in the adapter plate of the top nozzle, an inner socket formed on the upper ends of the guide thimbles, and a removable locking tube that is inserted in the inner socket to maintain it in locking engagement with the outer socket. The outer socket is in the form of a complement of special shaped bores having an annular groove. The inner socket is in the form of a sleeve having its lower end attached to the upper end of the guide thimble and with its upper end provided with a circumferential bulge which seats in the annular groove. Three elongated slots are provided in the upper end of the sleeve to permit inward elastic collapse of the slotted portion so as to allow the larger bulge diameter to be inserted through the bore of the adapter plate and expansion into the annular groove.

Abstract: To remove the bottom nozzle of a nuclear fuel assembly, the nozzle plate must be disconnected from the control-rod thimbles. For nozzles whose control-rod thimbles are connected to the nozzle plate by screw fasteners having lock pins welded to the nozzle plate, a cutter for severing the welds is provided. The cutter is rotated by a motor at the work position through a long floating shaft. A long feed shaft operated by a thumb nut at the work position feeds the floating shaft and cutter downwardly through the weld. The bushings extend from a bushing plate, each encircling a screw fastener. Each bushing has a yieldable sleeve for sealing the region around a screw fastener to trap the chips from the severed weld. The cutter is indexed from weld to weld by indexing plates. To remove chips adhering to the cutter, the suction tube of a suction-pump-operated eductor is inserted in the auxiliary hole and the cutter is inserted in the bushing and chips are removed by suction.