Westinghouse Electric Corporation

Stephen J Ferlan

John M Shallenberger

Stanley Kmonk

Pratap K Doshi

Alan Savinell

Dennis J Cadwell

John D Wood

Leonard T Gesinski

John M Schallenberger

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. Abutments formed at the other pair of diagonal corners of the adapter plate define a second set holes through the adapter plate for use in latching handling equipment directly to the adapter plate for lifting of the top nozzle.

Extended burnup top nozzle for a nuclear fuel assembly

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. The coupling structure is operable for connecting the lift assembly and handle pole in a first connected relation in which the lift assembly can be rotated by rotation of the handle pole between unlocked and locked positions relative to the top nozzle and unlatched and latched positions relative to the anchor assembly or in a second connected relation in which the lift assembly can be axially moved by rotation of the handle pole along the handle pole relative to the anchor assembly to cause lifting and detaching of the top nozzle from the guide thimble.

Hand held tool for removing and replacing a removable top nozzle

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.

Nuclear fuel assembly debris filter bottom nozzle

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.

Method for loading fuel rods into grids of nuclear fuel assemblies

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. Also, a securing nut having a central bore, an open bottom end and a closed top end, is inserted over the pilot portion and the externally-threaded portion of the upper end plug and has a radially flexible and expandable thread-defining element captured in the bore of the nut. The element is detachable fastened on the externally-threaded portion of the upper end plug to secure the upper end plug to the connecting finger.

Reconstitutable control rod spider assembly

Apparatus for loading fuel rods into grids of nuclear fuel assemblies

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.

Tool for replacing locking screws in a nuclear fuel assembly

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.

Reconstitutable nuclear fuel assembly having locking tubes with dimples

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.

Fuel assembly skeleton with structural and non-structural top

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. The dimples are so preformed and configured to have a generally pyramidal shape such that the metal forming the dimples substantially resists yielding and dimensional change regardless of the number of insertions and withdrawals of the tubular body into and from the locking position. Also, the dimples are located along the exterior of the tubular body and have outer tips diametrically displaced from one another across the tubular body such that when the body is inserted to the locking position, the dimples extend into the circumferential bulge defined in the guide thimble upper end portion and provide a positive interference fit with the guide thimble upper end portion above the circumferential bulge therein and with the upper portion of the adapter plate passageway wall which prevents inadvertent withdrawal of the tubular body from the locking position.

Reusable locking tube in a reconstitutable fuel assembly

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. Movement of the base toward the guide thimbles causes engagement with a guide thimble, and concurrently therewith operation, of each of the tools being mounted to the base which is adapted to rectify a respective one of the different types of guide thimble insert sleeve damage which is repairable. In addition, movement of the base toward the guide thimbles causes placement at an operative position, relative to a guide thimble, of each of the tools being mounted to the base which is adapted to rectify a respective one of the different types of guide thimble insert sleeve damage which is irreparable. Finally, a group of positioning elements is mounted in selected ones of the base openings for precisely locating the fixture relative to the guide thimble insert sleeves for accurate performance of repairable damage rectifying operations by the tools as the fixture is moved toward the guide thimbles.

Fixture and method for rectifying damaged guide thimble insert sleeves

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. A threaded shaft interconnects the upper and lower plate such that rotation of the shaft in either of two directions will move the upper plate between its upper and lower positions and move the cutters between raised positions withdrawn from the passageways and inserted positions where their cutting elements are disposed in the passageways and hollow upper end portions of the guide thimbles.

Apparatus and method for removing a top nozzle in reconstituting a fuel

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. Each actuating rod has a shaft portion which terminates in a lower enlarged nose disposed below the segmented rim of one flexure tube such that movement of the plates away from one another forcibly inserts each enlarged nose into one segmented rim sufficiently to expand the same to its first outside diameter size wherein the segmented rim will engage the lower end of each locking tube, whereas movement of the plates toward one another withdraws each enlarged nose from each segmented rim sufficiently to allow contraction of the same to its second outside diameter size wherein the segmented rim will fit through the locking tube.

Reusable locking tube insertion and removal fixture and method in a

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. However, prior to removing the top nozzle, a plurality of stop devices of the fixture are preset and operable for establishing a reference representing the distance between the fixture and work station so that the top nozzle can later be replaced at the same axial position on the fuel assembly it was at before removal.

Top nozzle removal and replacement fixture and method in a

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.

Growing community of inventors

Wilkins Township, PA, United States of America

Stephen J Ferlan