Abstract: The invention is directed to an apparatus for pulling a plurality of fuel ds out of a fuel element structure and has a gripping device which is capable of clamping the fuel rods. To reliably pull the fuel rods from an irradiated nuclear reactor fuel element, the apparatus includes an upper guide rod and a lower tension rod which lie horizontally and are arranged one above the other. The rods extend through a plurality of clamping plates in a direction perpendicular to the latter. The clamping plates are mounted so as to be parallel to each other and spacers are arranged between each two mutually adjacent ones of the clamping plates. The spacers are arranged on both rods with the width of the spacers on the lower rod beign slightly less than the diameter of a fuel rod. The clamping plates are pressable together by means of a tensioning device. The apparatus of the invention enables the gripping device to be placed on the fuel element in a simple manner.

Abstract: In an automated first weld apparatus, a transporter conveys nuclear fuel cladding tubes successively to a welding station where a separate end plug is welded to an open end of each tube. Thereafter, the transporter indexes the tubes successsively through a cooldown station where the weld is cooled, to a reader station where a unique end plug serial number is read, and then to a succession of inspection stations where the internal and external weld characteristics are automatically examined. The resulting inspection data is correlated with the associated serial number for record purposes and tested against quality assurance standards pursuant to sorting the tubes into accepted and rejected lots.

Abstract: A system for loading nuclear fuel pellets into tubular fuel pins. The system includes means for locating a fuel pin in registry with a pellet channel to enable a pellet stack to be displaced lengthwise into the fuel pin. The pellet channel and the pin locating means are mounted on a common structure. Linear vibrator means comprise first driving means arranged to urge the common structure in a lengthwise direction, and second driving means arranged to urge the common structure in a substantially perpendicular direction, so that the common structure is driven in a closed loop. Sensing means provide a signal upon cessation of pellet motion upstream of the fuel pin locating means. Means operable in response to said signal automatically adjust the phase relationship between said first and second driving means to effect reverse motion of the pellets.

Abstract: An easily manipulable nut 72 is disposed within a cavity 30 within an environmentally sealed military vehicle, such cavity being designed to hold a standard nuclear biological filter 10 within. The nut transfers a rotational force to a sleeve 16 which engages a seal 28 disposed about an outlet 24 of the filter. The nut ensures that the seal on the filter is compressed to the proper force. A lock mechanism 18 is provided about said sleeve to absorb shock and vibration forces which might tend to disengage the sleeve from the filter.

Abstract: An improved system for removing a plug from the open end of a heat exchanger tube in a nuclear steam generator is disclosed herein. It is particularly adapted for removing a plug formed from an elongated, cylindrical shell of Inconel.RTM. having a closed end, an open ends, and an expander element that radially expands the shell when axially drawn from the clossed to the open end of the shell. The system comprises an expander remover for axially pushing the expander element from the open end completely through the closed end of the plug shell, and a TIG torch for creating beads along the longitudinal axis of the plug shell which relax the engagement between the plug shell and the tube after the weld beams harden. Finally, the system includes a plug puller for pulling the loosened plug from the tube.

Abstract: An apparatus and method for remotely inserting and positioning a sleeve-loaded mandrel within a damaged tube mounted in the tubesheet of a nuclear steam generator is disclosed herein. The apparatus of the invention generally comprises a frame, a mounting mechanism for detachably and pivotally mounting the frame to the open end of one of a first tube in the tubesheet, an advancing assembly supported by the frame for remotely inserting and advancing the sleeve-loaded mandrel to a position across a damaged section of the selected tube, and a drive train for pivotally positioning the advancing assembly into alignment with the open end of the selected tube. In the preferred embodiment, the advancing means is formed from the pair of hydraulically operated grippers, one of which is reciprocably movable with respect to the other.

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 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: In order to transfer a bundle of rods of or from a nuclear fuel assembly into a storage case, the bundle is placed in a waiting position above a cassette provided with recesses. The rods are then introduced into the recesses by lowering them by gravity. When the cassette is full, it is brought into the extension of the case by interposing a transformation member. By simultaneously exerting a thrust on all the rods, the latter are compactly transferred into the case.

Abstract: A servicing machine for a steam generator is accurately set up in the generator channel head with a pivoted arm mounted for rotation in a plane parallel to the tubesheet. The angular position of the arm, the longitudinal position of a carriage mounted on the arm and the vertical position of a platform on the carriage are remotely controlled to maneuver a probe used in mapping the precise location of the thousands of holes in the tubesheet. Various operations are then performed at each precise hole location by tools carried by the arm mounted carriage to prepare for installation of new tubing. The operation of a pair of remotely controlled pivoted arms, one on each side of the channel head divider plate, is coordinated to automatically position the ends of U-shaped tubes in corresponding holes in the tubesheet on opposite sides of the divider plate and to secure the same in place.

Abstract: Process and device for locating the ideal screwing position of bolts of large dimensions wherein a bolt (10) is lowered under control until it engages in the tapping recess of an orifice (5), the bolt (10) is rotated in the opposite direction to screwing, the point of engagement of the threads (11) of the bolt (10) in the threads of the tapped orifice (5) is detected, screwing is started under control by the rotation of the bolt in the normal direction, successive seizures are detected during the screwing, and after each seizure the ideal screwing position is located by means of a suitable path from the center corresponding to the preceding stop previously recorded, screwing is resumed after each detection of the new ideal screwing center, and the screwing of the bolt (10) is continued at a high speed until the end of screwing is detected.

Abstract: The feed device comprises a housing (10) of sufficient size to contain a cylindrical piece (15), equipped with a removable cover (20), through which passes a nozzle (24) connected to a compressed-air distribution source (25, 26). A flexible pipe (11) is fastened at one of its ends to the housing (10). A loading unit (12) consisting of a fixed part (28) and of a rotary arm (29) is connected to the end of the flexible pipe (11) opposite the housing (10). The pieces (15) can, in particular, be plugs for plugging the tubes of a steam generator of a pressurized-water nuclear reactor.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: A tooling system and method for remotely removing a rod or other component located between the top and bottom nozzles of a fuel rod assembly is disclosed herein. Generally, the tooling system comprises a grinding mechanism including a carbide burr and a high speed air motor for grinding an opening through the adapter plate of the top nozzle of a size sufficient to allow the withdrawal of said component therethrough, a housing fixture connected to the carbide burr of the grinding mechanism for positioning the burr over a point in the adapter plate adjacent to the component to be removed, and an engagement assembly connected to the grinding mechanism for moving the carbide burr into grinding engagement with the adapter plate, and a gripping apparatus insertable through the hole produced by the grinding mechanism for gripping the rod or other component and withdrawing it through the opening.

Abstract: For sampling a section of a tube in a nuclear fuel assembly comprising a skeleton formed by two end-pieces joined by tubes fixed to the end-pieces an opening for the extraction of the section through the upper end-piece is cut out with a milling cutter. Through the inside and by means of a cutting tool, the spacer tube is cut off at a level beneath the junction with the upper end-piece by means of a rotary tool introduced through the upper end-piece and the latter is extracted through the opening.

Abstract: Apparatus for releasably engaging an elongated member that is releasably connected to the top nozzle of a nuclear reactor fuel assembly. The top nozzle has an adapter plate disposed at its lower end having at least one passageway therethrough through which the elongated member is disposed. The elongated member has a releasable latching structure at one end that is able to be engaged by the apparatus, having at least one latching member movable between a latched position in which the latching member is able to engage said adapter plate and secure the absorber rod in a stationary relationship with respect to the adapter plate and an unlatched position in which the latching member is able to disengage from said adapter plate so that the elongated member be removed from the fuel assembly.

Abstract: Bodies such as nuclear fuel pellets are formed into a stack in a stacking lane (34) and the length of the stack is measured at intervals by device (40) to determine if the partly-formed stack is drifting away from a target length. Pellets are issued into the stacking zone (34) by a selector mechanism (32), the input of which receives pellets from three lanes (24, 26, 28) containing oversize, undersize and intermediate size pellets and the pellets issued to the stacking lane (34) are selected under the control of microprocessor-based unit (18) according to the extent of any drift from the target value. The pellets in lanes (24, 26, 28) are derived from a common supply (12) following segregation by a diverter mechanism (22) controlled by unit (18) in accordance with length measurements made by measuring device (16).

Abstract: A fuel assembly fabrication apparatus includes a stationary support fixture and a slide fixture mounted to one end portion thereof for movement therealong. Clamp structures are disposed in spaced relation longitudinally along the stationary support fixture. One clamp structure is mounted on the movable slide fixture and supports a top nozzle and an uppermost one of a plurality of grids of a fuel assembly. The remaining clamp structures are mounted on the stationary support fixture and support a bottom nozzle and the remaining grids. The clamp structures respectively support the top nozzle and uppermost grid and the bottom nozzle and remaining grids in generally parallel relationship with passageways defined in the top and bottom nozzles and sleeves connected on the grids being aligned for slidably receiving therethrough a plurality of guide thimbles and an instrumentation tube of the fuel assembly for attachment to the nozzles and grid sleeves.

Abstract: A replacement station includes an old split-pin-assembly (OSPA) removal stand and a new split-pin-assembly (NSPA) installation stand. The removal stand includes a saw and a drill. With the guide tube to which the OSPA is secured in the removal stand, the saw severs each OSPA below the flange which engages the base of the lower counterbore in the lower guide tube (LGT) separating the OSPA into a pin fragment and a second fragment including the flange and the remainder of the split-pin with the nut threaded into it. The second fragment remains secured to the LGT after the sawing operation. The guide tube is rotated so that the drill is coaxial with the shank of the pin of the second fragment. The second fragment is separated into a third fragment including the flange and a fourth fragment including the remainder of the pin and the nut both removable from the LGT. The installation stand has NSPA blades in which the new split pins are mounted. The LGT sans the OSPA's is positioned on the installation stand.

Abstract: A marked reduction in the pressure drop of cooling liquid through a grid spacer of a nuclear fuel assembly is attained by convexly contouring the upstream (usually the lower) edges of the grid members. Preferably, they are made streamlined or semicylindrical. This can be done by first beveling and then etching them, by directing a stream of mixture of abrasive and an organic polymer against them, or by traversing an electron or laser beam along them at a power and velocity such as to cause local melting. A lesser improvement is secured by beveling alone. A still further improvement can be obtained by also tapering the downstream (usually upper) edges.

Abstract: An apparatus for automatically loading one or more kinds of nuclear fuel pellets in fuel cladding tubes for producing nuclear fuel rods comprises at least one pellet transporting tray transferred from a tray stacking unit and provided with a plurality of grooves on which the fuel pellets are mounted, at least one pellet aligning tray provided with a groove selectively connected with one of the grooves of the pellet transporting tray at one end of the aligning tray, and a fuel cladding tube supporting device located in the vicinity of the other end of the aligning tray and adapted to support a number of fuel cladding tubes so that a selected one fuel cladding tube is operatively connected to the aligning tray. The fuel pellets are transferred from the transporting tray into the aligning tray by means of a pushing device and the row of the pellets transferred on the groove of the aligning tray is moved forwardly until it abuts against a stopping mechanism located in association with the aligning tray.

Abstract: A nuclear fuel rod loader for pulling fuel rods into a fuel assembly skeleton has a rod gripper with slots defining fingers. The rod gripper passes through the grids of the skeleton on its way to a fuel rod magazine. An inner shaft of the rod gripper spreads open the fingers to engage a groove in the cavity of the end plug of the fuel rod. The rod gripper is retracted, pulling the coupled fuel rod into the fuel assembly skeleton. The rod gripper has a chamfer surface at the closed slot end of each slot to avoid the rod gripper damaging a dimple during entry into the grids of the fuel assembly skeleton. The rod gripper has a stress relief surface at the closed slot end of each slot to avoid failure in the flexing fingers.

Abstract: An apparatus for the simultaneous shearing of two sides of the boiling water nuclear reactor control rod. The rotation of the rods at 90 degree rotation and the shearing of the second two sides underwater in a nuclear waste storage pool.In a previous application by A. H. Krieg, Ser. No. 692,849, we have seen the crushing of a BWR control rod for the purpose of reducing nuclear radioactive waste. The control rod however has an end referred to as the velocity limiter end, which is round and bulbous. This end can not be crushed practically, due to its mass. The purpose of this invention is to shear or cut-off the velocity limiter from the rest of the control rod thus having the remaining cruciform crushable. Between the velocity limiter and the rest of the control rod are 2 "D" shaped holes, hereafter refered to as the "D" holes. At this point the control rod is solid and does not contain hollow fins or boron rods.

Abstract: A fuel assembly has a plurality of fuel rods arranged and held in parallel with one another in the cells of spacer assemblies arranged at suitable intervals. During the assemblying and transportation of the fuel assembly, flexible sleeves are inserted in respective cells such as to separate the fuel rods from parts provided on the walls of the cells, thereby protecting the fuel rod surfaces against any damage and scratch which may otherwise be caused due to interference between the fuel rod surface and the parts provided on the walls of the cell.

Abstract: This hooking device is fastened to the choke plug (8) for guide tube (2). comprises of catches (54) regularly arrayed along the periphery of the flange (9) of the choke plug (8) and hooks to the upper spacer (4S) of the guide tube (2). It is kept in the engaged position by a spring system (56-58), 63-65) and can disengage by means of a tool means comprising a roller (77) acting on each catch (54) and a rim (68) resting on a muff (56) acting as a rest also for the spring (57).

Abstract: The tube plug removal machine removes any type of tube plug by drilling into a plug portion with a tap drill bit, engaging that plug portion with a threaded section of the tap drill bit after the drilled hole has been threaded by a tapping section thereof, and removing a portion of the tube holding the plug in the tube with a counterbore drill bit mounted concentrically about the tap drill bit. A trip pin and trip spline enable the tap drill bit to be automatically disengaged from the motor once the tap drill bit has been threaded into engagement with the plug. The conterbore drill bit is thereafter self-centered with respect to the tube and plug about the now stationary tap drill bit. After a portion of the plug has been removed by the counterbore drill bit, pulling on the tap drill bit will remove the remaining plug portion from the tube.

Abstract: An apparatus for consolidating the nuclear fuel elements originally arranged in a square pattern into a truss of tightly packed elements comprises a vertical quiver of pyramidal shape having lateral surfaces converging downwardly and a rectangular cross-section. Two opposite faces of the quiver are formed with projections of downwardly increasing amplitude for rearranging the elements in a triangular pattern when they are lowered into the quiver. Dividing walls perpendicular to those faces which are provided with projections separate and guide rows of elements at the top part of the quiver. A grid at the top of the quiver comprises compartments for introducing elements and consists of several fractions which may be moved apart from each other and brought together along a direction parallel to the dividing wall.

Abstract: The apparatus is intended for rebuilding an assembly comprising a skeleton formed by two end members connected by tie rods attached to the end members and grids distributed between the end members along the tie rods and adapted to retain a cluster of fuel rods trapped between the end members. The apparatus comprises a first chamber (AI) for receiving a fuel assembly, a second chamber (AS) for receiving a new skeleton, a repair station comprising a lift adapted to receive the two vertically disposed aligned chambers and to bring the chambers to a level such that there subsists a layer of protective water above the rods, a transfer tool (106) to draw one fuel rod at a time into the skeleton from the assembly contained in the first chamber, and means for mounting the end members on the skeleton.

Abstract: Both a grinding tool and a thimble screw alignment plate are disclosed herein that greatly facilitate the removal and reinstallation of the bottom nozzle of a fuel assembly. The grinding tool includes a base plate, a grinding motor, a grinding head, a housing for isolating the grinding motor from ambient water, and both a guide mechanism and linear drive for guiding and pushing the grinding head into abrasive contact with a screw-obstructing portion of a bottom nozzle. The screw alignment plate includes a plurality of bores registrable with the screw holes of a bottom nozzle, and a resilient sleeve mounted over each bore for receiving, retaining and aligning the threaded end of a screw with each such screw hole.

Abstract: The system of the invention includes a downender station 10 which receives and secures a spent fuel assembly 20 in a vertical disposition and is then pivoted to a horizontal position after the upper nozzle has been removed, and a second station 12 generally aligned with the first station includes a multiple rod gripper 56 which is used to grip onto the exposed fuel rod ends and pull the fuel rods to an upper horizontal location in the second station, with horizontal and vertical combs 60 and 62 maintaining the original square pitch array of the rods, and the rods are then dropped into a reconfiguring structure 70 where they assume a more compact array, the rods then being pushed by pusher 74 into a storage canister 26 carried by the downender below the fuel assembly 20. The arrangement permits compacting fuel rods from two fuel assemblies into a storage canister 26 having approximately the same transverse cross-sectional area as a single fuel assembly.

Abstract: An apparatus for inserting rods of a rod bundle from a nuclear reactor fuel assembly into a vessel includes a dense-setting device including: a holding cage for laterally holding the rods together in a given dense packing with mutually parallel longitudinal axes, the cage having a bottom on which one end of each of the rods stand; an insert associated with the holding cage having two ends and guide channels receiving the rods, the guide channels defining an outlet cross section at one end near the bottom with outlet openings disposed according to the given dense packing, and the guide channels defining an inlet cross section at the other end at which the rods are inserted with inlet openings disposed according to the position of the rods in the rod bundle, the insert including a plate having the inlet openings formed therein defining the inlet cross section, the plate being movable toward the outlet cross section against a spring up to a stop; and a pulling tool for pulling the insert out of the holding cage

Abstract: A method and apparatus for installing a mechanical tube plug 74 to assure the integrity of the seal between the tube plug 74 and tube 66. The actual torque applied in accomplishing each step in the tube plug installation process is monitored and recorded to assure that the integrity of each step of the tube plug installation process is maintained and, therefore, the integrity of the seal is assured.

Abstract: The guide tube is disconnected and removed from the upper internals of the reactor to a work station in a pool of borated water. The work station includes a clamp-and-index tool, a metal-disintegration-machining (MDM) tool, pick-and-put tool, a brush tool, a nut hopper, a pin-insertion/torque tool, and a crimping tool. These tools are hydraulically operable. The clamp-and-index tool positions and, by repeated centering maintains the guide tube in precise position for removal and replacement of its split pins, the MDM burns through an old pin-and-nut assembly severing it into readily removeable fragments. This pin fragment is removed by an expeller on the clamp-and-index tool. This pick-and-put tool removes the burned nut fragment and replaces it with the new nut. The pin-insertion/torque tool inserts the new pin and torques the new nut onto the new pin. The crimping tool crimps a locking cap secured to the nut onto the pin. The tools are controlled from a command center external to the pool.

Abstract: A steam generator for nuclear power plant applications. U-shaped heat exchanger tubes within said steam generator are provided with compliant antivibration bars at the U-shaped portion of the tubes. Flexible plates located at opposite sides of the antivibration bars are placed in contact with the opposite sides of the rows of tubes. Support ribs spaced along the length of the compliant bars limit the deflection of the flexible plates and establish the effective length of the flexible plates. The ribs in successive columns of antivibration bars are located between the ribs of the bars of each preceding and following row.

Abstract: A system for remotely repairing nuclear fuel rod assemblies is disclosed herein. Generally, the system comprises a rod handler for gripping, lifting, lowering and ungripping a selected fuel rod, a work station for securing the nuclear fuel rod assembly to be repaired into a desired location, and a positioner device for laterally positioning the rod handler over a selected rod in the fuel assembly secured within the work station. The rod handler includes a contractable collet for gripping and ungripping a desired fuel rod, and a rod sensor concentrically disposed within the collet for sensing when a rod is in a grippable position. The positioner includes a movable carriage which is slidably mounted onto a frame assembly by means of a pair of rail and bearing mechanisms. The system also includes a microcomputer for controlling the manner in which the positioner positions the rod handler, as well as gripping, lifting, lowering and ungripping motions of the handler itself.

Abstract: An insert for providing a reduced inside diameter for a structural tube, specifically an instrumentation guide tube, of a nuclear fuel assembly. The insert has forming lobes which coact with the structural tube to plastically deform the structural tube and mechanically lock it with respect to grid straps of a grid assembly. The insert also has centering lobes to prevent it from being expanded in other than a coaxial alignment with the structural tube. An expansion tool is provided for sequentially registering with and expanding sequential forming lobes in a simplified manner whereby all of the operations necessary to assemble the structural tube in the fuel assembly can be easily and accurately performed.

Abstract: A remotely controlled tooling apparatus is disclosed for supporting and selectively disposing a tool with respect to a workpiece illustratively taking the form of a core barrel of a nuclear reactor. Illustratively, a core barrel is of a substantially cylindrical configuration and has a plurality of flow holes disposed therethrough. The remotely controlled apparatus comprises a tool carriage, a support table carried thereby for receiving the tool, a strongback assembly for supporting and guiding the tool carriage with respect to the core barrel, and a pair of clamps affixed to the strongback assembly for engaging the core barrel for suspending the strongback assembly upon the core barrel. The tool carriage and its support table carried thereby are selectively disposed with respect to the core barrel, whereby the tool may be engaged and disengaged with and from the core barrel.

Abstract: Horizontal fuel element bundle shears have a stepped blade and a horizontal agazine for accommodating an undismantled uclear reactor fuel element which is to be cut up. In the fuel element bundle shears, the nuclear reactor fuel element, for the cutting operation to be performed, is pushed with a stepwise movement through a magazine opening in front of which the stepped blade is displaceable in a direction perpendicular to the longitudinal axis of the fuel element. Each portion of the stepped blade has a cutting edge. In order to achieve a lower rate of wear of the stepped blade while at the same time obtaining a good cut and a low cutting force, the stepped blade has two cutting edges which are separated from each other by a step, thereby forming two blade portions which are in superposed relationship with each other.

Abstract: A method and apparatus for withdrawing spent fuel rods from a nuclear fuel rod assembly into a different nuclear fuel rod container wherein the spent fuel rods have a higher fuel rod density, whereby a greater number of spent fuel rods can be stored in a water-storage pool. The individual rods are moved from a fuel assembly and through a transition funnel by movable grippers at opposite ends of the funnel. One movable gripper reciprocates between gripping and release positions in a gap between the fuel assembly and the transition funnel. A stationary gripper can be located in the gap at the entry side of the funnel to hold the fuel rods while the movable gripper returns from a release position to the gripping position. Both grippers include members which can be pressed into frictional engagement with the spaced apart array of fuel rods. All of the fuel rods are withdrawn concurrently and are merged toward one another into a tighter array within the transition funnel and emerge as a bundle.

Abstract: A grid assembly fixture for use in assembling grid straps to form a grid comprises a generally flat plate having first and second sets of parallel grooves, with the grooves of the sets at right angles. A retention strap comprises first and second pairs of bars, the bars of each pair hinged together adjacent their ends, and releasable joining elements for joining the pair of bars.A method of assembling the grid straps includes positioning a first set of straps in a grid assembly fixture, positioning a second set of straps at right angles to the first set to form a grid, placing outer straps on the grid, and placing a retention strap on the outer straps.

Abstract: A method of repairing under water a boiling water reactor-fuel assembly having a fuel assembly channel and an upper grid plate by means of a channel stripping machine, disassembling the upper grid plate, determining a damaged fuel rod and exchanging the damaged fuel rod for another fuel rod by means of a fuel rod exchanging device, which includes, after stripping off the fuel assembly channel and disassembling the upper grid plate at the location thereof in the channel stripping machine, placing on the fuel assembly a guide box with which the fuel rods of the fuel assembly are centered, then placing thereon an indicator plate and determining the varying growth of the fuel rods, and replacing the indicator plate by a centering plate to which the fuel rod-exchanging device is coupled and a device for carrying out the method.

Abstract: The invention relates to a spacer arranged to retain and fix elongated fuel rods into bundles insertable into a nuclear reactor fuel assembly, said spacer being of a zirconium alloy having a low neutron absorption. To counteract play and hence wear in case of increasing burnup when the springs relax and the rod diameter is reduced by shrinkage, the spacer is made with different textures in the springs (2, 3) and the surrounding structure (1, 6). The difference in texture gives the springs a great axial irradiation growth and the surrounding structure a small axial irradiation growth, which contributes to a remaining deflection tendency of the springs in relation to the surrounding structure during the life of the fuel assembly.

Abstract: A cutting tool is manually operable from above the water level in a reactor cavity pool to sever locking cups from the socket-head cap screws which hold guide tubes to the upper support plate of the upper internals of the reactor. The tool includes a support assembly adapted to be mounted on the guide tube. A motor frame is mounted on the support assembly for limited vertical movement with respect thereto and carries a hydraulic motor coupled by a vertically depending shaft to a tubular cutter for rotating same about its axis. The shaft extends through an opening in the support assembly and through a locating tube which surrounds the cutter and is receivable over the associated locking cup when the support assembly is mounted in place. A drive screw is coupled to the frame and to a shaft which extends up to the coupling tube to a manually operable crank to effect vertical movement of the frame and the cutting means coaxially with respect to the locking cup to sever its top wall from its side wall.

Abstract: Apparatus for processing the damaged tubes of a steam generator. This apparatus includes a sleeving tool for inserting sleeves in the tubes, a high-roller tool for rolling the sleeves at their upper ends where they have been expanded, and a low-roller tool for rolling the sleeves at their lower ends in the tube sheet. Each tool is provided with locking pins which engage tubes adjacent to a tube to be processed and suspend the tool in processing position. The sleeves are inserted in the tubes and are rolled by rolls driven by a hydraulic motor. For sleeve insertion and for high and low rolling, the motor is controlled by a servo control valve. The feedback signal to this valve is derived from a flow transducer in the feed line for the motor. The feedback for the force of sleeve insertion is the pressure across the motor derived from pressure transducers in the conductors through which the motor is supplied. For insertion speed and for rolling speed, the feedback is derived from a fluid-flow transducer.

Abstract: Neutron absorber rods are mounted with their upper ends in bores formed in a mounting device and the absorber rods are movable within guide tubes of a nuclear reactor fuel assembly. A holding device is firmly attached to a fixed location of the storage pit. The holding device has holder tubes for absorber rods. In order to replace the absorber rods, the mounting device with the neutron absorber rods is placed and locked in the holding device, the mounting device is disconnected from at least one neutron absorber rod to be replaced, the mounting device with any neutron absorber rods still attached to it is removed from the holding device, the disconnected neutron absorber rods remaining in holder tubes of the holding device are removed for storage, new neutron absorber rods are placed in the empty holder tubes and the mounting device with any neutron absorber rods still connected to it are placed in the holding device and the mounting device is connected to the new neutron absorber rods.

Abstract: An improved apparatus for applying an end plug to an end of a fuel rod tube includes a housing having spaced inlet and outlet ends adapted to receive the end plug and tube end, respectively, one of three alternative embodiments of a guide arrangement which defines an internal guide channel aligned in tandem with the inlet and outlet ends of the housing along a common axis, and cylindrical ram movable along the axis for engaging and moving the end plug from the inlet end through the guide channel to the outlet end where the plug is applied to the tube end.

Abstract: The old split-pin assemblies of the lower guide tube of a nuclear reactor are replaced by new split-pin assemblies in a robotic work station under a pool of water. The work station includes a plurality of robotic tools which are remotely actuable from a robotic command center outside of the pool to position the guide tube precisely for a replacement operation, to fragment the old split-pin assemblies and dispose of the fragments under water, and to install a new split-pin assembly. The lower-guide-tube positioning means has a hydraulic cylinder, also remotely actuable externally to the pool, for rotating the guide tube so that it may be oriented properly to be processed by different tools in succession and also so that both split-pin assemblies in each guide tube may be replaced by the same set of tools.

Abstract: An apparatus for moving and positioning a tool for plugging a defective heat exchanger tube of a steam generator in a nuclear reactor includes a base, a plug magazine supported on the base, a guidance mechanism mounting the plugging tool and a positioning mechanism supported on the base and mounting the guidance mechanism. The guidance mechanism is operable to align and position the tool relative to the plug magazine and the defective heat exchanger tube to correspondingly effect, upon operation of the tool, plug loading when the tool is located in a plug dispensing position adjacent to the plug magazine and plug unloading when the tool is located in a plug applying position adjacent to the defective tube. The positioning mechanism is operable to assume folded and unfolded conditions to transfer the guidance mechanism and the plugging tool therewith respectively between the plug dispensing and applying positions.

Abstract: A pushing device for removing spent fuel rods from a nuclear reactor fuel assembly comprises a plurality of axially shiftable rods disposed in the same geometric pattern and with the same pitch as the fuel rods. The push rods are mounted at their upper ends to a pressure strip or plate and traverse at their lower ends bores in a guide plate fixed via guide rods to a base plate located on the other side of the pressure plate, the pressure plate being movably secured to the guide rods for linear motion between the base plate and the guide plate. A drive mounted to the base plate is connected to the pressure plate for shifting the latter, while a safety mechanism is provided for interrupting the motion of a push rod if the respective fuel rod is jammed in the fuel assembly.

Abstract: An improved apparatus for applying an end plug to an end of a fuel rod tube includes a housing having spaced inlet and outlet ends adapted to receive the end plug and tube end, respectively, one of three alternative embodiments of a guide arrangement which defines an internal guide channel aligned in tandem with the inlet and outlet ends of the housing along a common axis, and a cylindrical ram movable along the axis for engaging and moving the end plug from the inlet end through the guide channel to the outlet end where the plug is applied to the tube end.