Abstract: A fast neutron nuclear reactor contains a nuclear reactor core having an array of device locations. Some device locations in the nuclear reactor core contain fissile and fertile nuclear fuel assembly devices. One or more other device locations in the nuclear reactor core contain Doppler reactivity augmentation devices that amplify the negativity of the Doppler reactivity coefficient within the nuclear reactor core. In some implementations, a Doppler reactivity augmentation device can also reduce the coolant temperature coefficient within the nuclear reactor core. Accordingly, a Doppler reactivity augmentation device contributes to a more stable nuclear reactor core.

Abstract: A tubular delivery arm that travels vertically along a rail on the front of a drilling mast in generally parallel orientation to the travel of a top drive. The tubular delivery arm has a dolly vertically translatably connected to a mast of the drilling rig. An arm is rotatably and pivotally connected to the dolly at its upper end. A tubular clasp is pivotally connected to the arm at its lower end. The dolly vertically translates the front side of the mast in response to actuation of a hoist at the crown of the mast. The tubular delivery arm translates the mast in non-conflicting passage of a top drive connected to the same mast, for positioning a tubular stand over the centerline of the wellbore, a mousehole, or a stand hand-off position.

Abstract: A tubular delivery arm that travels vertically along a rail on the front of a drilling mast in generally parallel orientation to the travel of a top drive. The tubular delivery arm has a dolly vertically translatably connected to a mast of the drilling rig. An arm is rotatably and pivotally connected to the dolly at its upper end. A tubular clasp is pivotally connected to the arm at its lower end. The dolly vertically translates the front side of the mast in response to actuation of a hoist at the crown of the mast. The tubular delivery arm translates the mast in non-conflicting passage of a top drive connected to the same mast, for positioning a tubular stand over the centerline of the wellbore, a mousehole, or a stand hand-off position.

Abstract: A transfer system for spent fuel canisters includes a carrier, a shielded bell trolley movable along the carrier and carrying a shielded bell, and a canister trolley movable along the carrier and carrying a lifting mechanism for raising and lowering the spent fuel canister into and out of the shielded bell. The canister trolley can move along the carrier independent of the shielded bell trolley and the shielded bell trolley can move along the carrier independent of the canister trolley. The shielded bell trolley and the canister trolley can be selectively interlocked for selected transfer operations.

Abstract: The cooling duct assembly for a control element drive mechanism (CEDM) includes a skirt that is combined on a circumference of a reactor head and has first air channels in an inner side thereof; a lower duct that is combined with an upper side of the skirt, has second air channels that are connected to the first air channels, and is disposed to surround a circumference of the CEDM; and an upper duct, an edge of which is combined with the cooling air handling device, and other edge of which is detachably combined with the lower duct, wherein air that cools the CEDM is discharged to the outside after sequentially passing the first air channels, the second air channels, the upper duct, and the cooling air handling device, and the upper duct separated from the lower duct is lifted together with the cooling air handling device.

Abstract: Detecting diversion of spent fuel from Pressurized Water Reactors (PWR) by determining possible diversion including the steps of providing a detector cluster containing gamma ray and neutron detectors, inserting the detector cluster containing the gamma ray and neutron detectors into the spent fuel assembly through the guide tube holes in the spent fuel assembly, measuring gamma ray and neutron radiation responses of the gamma ray and neutron detectors in the guide tube holes, processing the gamma ray and neutron radiation responses at the guide tube locations by normalizing them to the maximum value among each set of responses and taking the ratio of the gamma ray and neutron responses at the guide tube locations and normalizing the ratios to the maximum value among them and producing three signatures, gamma, neutron, and gamma-neutron ratio, based on these normalized values, and producing an output that consists of these signatures that can indicate possible diversion of the pins from the spent fuel assembl

Abstract: The invention refers to a device and a method for handling a fuel assembly (3), which comprises a number of fuel rods extending between a lower part and an upper part of the fuel assembly, a debris filter located in the lower part of the fuel assembly and a casing surrounding the fuel rods. The device comprises a lifting device (15) for engaging, during a lifting operation, a fuel assembly located in a reactor vessel (1) and lifting the fuel assembly upwards and out from the reactor vessel. A conduit member is connected to the upper part of the fuel assembly. A pump (32) creates a flow of water through the conduit member and the fuel assembly during the lifting operation. The flow has such a size that possible debris particles contained in and/or immediately beneath the debris filter at least are retained in and/or immediately beneath the debris filter during the lifting operation.

Abstract: A storage container is carried into a nuclear-reactor containment, and then, the core structure is housed in the storage container. In this process, a bottom cover is carried to a storage-container body by using a moving device. The storage-container body and the bottom cover are positioned by adjusting the position of the bottom cover on the moving device while the bottom cover is supported by free bearings. The bottom cover is then attached to the storage-container body.

Abstract: A fuel exchange apparatus, comprising: a traveling carriage moving horizontally in one direction; a traversing carriage moving horizontally on the traveling carriage in a direction orthogonal to the one direction in which the traveling carriage moves; and a fuel holding unit attached to the traversing carriage, and including an telescopic tube enabling to extend and contract, a holding tool for holding a fuel assembly and releasing the held fuel assembly, and a lifter for raising and lowering the holding tool by winding and running out linear members for suspending and supporting the holding tool from the traversing carriage, wherein the holding tool is selectively placed in a constrained state in which the holding tool is subject to a constraint by the telescopic tube and in a freely suspended state in which the holding tool is released from the constraint by the telescopic tube and freely suspended by the linear members.

Abstract: A method of aligning a nuclear fuel bundle and handling selected fuel rods within the fuel bundle located in a spent fuel pool of a nuclear power plant. The bundle includes water rods, full-length and part-length fuel rods extending through a plurality of fuel spacers provided between top and bottom ends of the bundle, each spacer having a plurality of cells accommodating corresponding fuel and water rods. The method includes insertion of a rod grapple tool into a top end of a fuel bundle and down to a desired location within the bundle. A guide pin retrieval tool inserts into a side of the fuel bundle to remove a guide pin from a distal end of a gripper of the rod grapple tool, allowing the guide pin retrieval tool to grip a part-length fuel rod within the fuel bundle.

Abstract: A signal processing apparatus includes: a digital processing unit to which a digital input signal is supplied, which performs a digital process on the digital input signal to produce a digital signal, and which produces a control signal designating a specific time period when an amplitude of an analog output signal is to be lowered; a DA-conversion unit which converts the digital signal to produce an analog signal; and a variable gain unit which adjusts an amplitude of the analog signal to produce the analog output signal, and which lowers the amplitude of the analog output signal during the specific time period designated by the control signal.

Abstract: An outer filter removal tool for a boiling water reactor control rod drive that uses a mechanical advantage obtained through the use of lead screw threads to pull the outer filter off of the control rod drive. Fingers on the tool are closed around the upper flange of the outer filter by sliding a collar over the outwardly biased fingers. A shaft extending through the tool is rotated which in turn extends a push plate against the control rod drive index tube causing the fingers to pull against the upper flange on the outer filter until the filter is freed from the control rod drive. The tool will hold the filter in place until affirmatively released for proper disposal.

Abstract: In a spent fuel pool of a nuclear power plant, there is provided a system for aligning a nuclear fuel bundle and handling selected fuel rods within the fuel bundle. The bundle includes water rods, full-length and part-length fuel rods extending through a plurality of fuel spacers provided between top and bottom ends of the bundle, each spacer having a plurality of cells accommodating corresponding fuel and water rods. The system includes a bundle alignment system for aligning the fuel rods and water rods, a rod grapple tool to extract selected part-length rods from the bundle, and a fuel rod guide block slidable onto the top end of the bundle for protecting an uppermost fuel spacer of the bundle, and for aligning fuel rods within individual cells of all the fuel spacers in the fuel bundle.

Abstract: The invention relates to a method for transferring an article from a fluid-filled first vessel into a fluid-filled second vessel or in the opposite direction. The vessel is connected by a connecting element, in which there is a transport device for moving the article. A fluid flow flowing out of the first vessel is maintained in one part of the connecting element, while the article is transported through the connecting element. An apparatus for transferring an article, in particular a nuclear fuel element, between the vessels is also described, in which an extraction device for the discharge of fluid is located on the connecting element.

Abstract: A method and apparatus is disclosed for smoothly inserting a fuel rod loader through the skeleton of a fuel cell and then for pulling an attached fuel rod into the fuel rod skeleton while keeping the fuel rod under constant tension and preventing the bowing of the fuel rod. The pulling mechanism comprises a smooth collet with a smooth bullet end cap for guiding the puller mechanism into and through the skeleton where the bullet end cap is removed and the fuel rod is attached with a unique ball and slide mechanism actuated by a long puller rod that grabs the end of the fuel rod by a forward motion of the puller rod and is easily removed from the fuel rod by reversing this motion once the fuel rod is in place.

Abstract: The invention relates to a method for transferring an article from a fluid-filled first vessel into a fluid-filled second vessel or in the opposite direction. The vessel is connected by a connecting element, in which there is a transport device for moving the article. A fluid flow flowing out of the first vessel is maintained in one part of the connecting element, while the article is transported through the connecting element. An apparatus for transferring an article, in particular a nuclear fuel element, between the vessels is also described, in which an extraction device for the discharge of fluid is located on the connecting element.

Abstract: A removable rail assembly for use with a spent fuel handling machine, including a support rail, a rail guide carried by the support rail, a rail joint connector supported by the rail guide for coupling the rail guide to adjacent rails, and at least one jacking screw supported by the support rail for lifting the support rail assembly. Another embodiment of the invention includes a second jacking screw received in the top surface of the rail guide. The joint connector is tongue and groove joint with a tapered parting line that permits a tight fit between the removable rail and adjacent fixed rails. During removal of the removable rail, the jacking screw distributes a uniform lifting force along the length of the rail, loosening the joint connector. Once the joint connector is loosened, the rail is coupled to a lifting crane and transported to a storage area.

Abstract: A loading machine for simultaneously transferring fuel elements between a reactor core and a storage rack in a nuclear power station has a mast divided into individual mast parts. Each mast part has its own gripping and guiding devices for gripping and holding the individual fuel elements. The mast is provided on a trolley. At least one of the mast parts is movable horizontally on the trolley and is rotatable about its longitudinal axis. The individual fuel elements can be lifted out of the reactor core simultaneously, their position relative to each other can be changed, and the fuel elements can be set down on a storage rack or a workplace. A method for transferring fuel elements in a nuclear power station is also provided.

Abstract: The present invention provides a method and apparatus for fuel handling in a nuclear reactor. The nuclear reactor has a reactor vessel comprising a reactor core with a plurality of fuel assemblies and control rods. A fuel pool is arranged adjacent to the reactor vessel. A group comprising at least a plurality of fuel assemblies is simultaneously lifted out of or into the reactor vessel with a single gripper, the gripper having a plurality of gripping devices. The group is transported between the reactor vessel and the fuel pool by means of the gripper.

Abstract: A refueling machine having relative positioning capability for refueling a nuclear reactor. The refueling machine includes a pair of articulated arms mounted on a refueling bridge. Each arm supports a respective telescoping mast. Each telescoping mast is designed to flex laterally in response to application of a lateral thrust on the end of the mast. A pendant mounted on the end of the mast carries an air-actuated grapple, television cameras, ultrasonic transducers and waterjet thrusters. The ultrasonic transducers are used to detect the gross position of the grapple relative to the bail of a nuclear fuel assembly in the fuel core. The television cameras acquire an image of the bail which is compared to a pre-stored image in computer memory. The pendant can be rotated until the television image and the pre-stored image match within a predetermined tolerance.

Abstract: An extraction tool for removing a partial length fuel rod from a fuel bundle assembly, wherein the partial length fuel rod has an upper end plug, the tool comprising an extension rod having a pair of gripper jaws mounted at one end thereof, the gripper jaws shaped and sized to engage the upper end plug; and a locking tube slidably received over the extension rod and engageable with the gripper jaws to lock the gripper jaws to the upper end plug.

Abstract: A tool for vertically supporting a shroud repair tie rod assembly having a clevis hook by bracing the clevis hook against a clevis pin installed in a gusset plate. This allows the vertical support at the upper end of the tie rod assembly to be removed, so that the upper support structure can be coupled to the tie rod. The lower end of the tie rod assembly is supported on both sides of the gusset plate. The tool for vertically supporting the lower end of the tie rod assembly is designed to fit in the narrow space bounded by a jet pump diffuser, the gusset plate and the reactor pressure vessel. The vertical support tool includes a pole adaptor for coupling to the end of a service pole, a pole adaptor extension having one end connected to the pole adaptor, a mounting block connected to the other end of the pole adaptor extension, and a hydraulic spreader mounted on the mounting block. The hydraulic spreader opens in response to actuation of a hydraulic cylinder.

Abstract: A refueling machine for refueling a pressurized water reactor has a trolley which travels on rails mounted on a transversely movable bridge. The trolley supports a refueling mast which includes an outer mast and two horizontally spaced apart, vertically movable gripper masts disposed within the outer mast. This design permits the machine to safely handle two fuel assemblies simultaneously in order to substantially reduce refueling critical path time. The two gripper masts can be raised, lowered and otherwise operated independently of each other. A partition plate extending through the stationary mast between the two movable gripper masts permits each fuel assembly held in the refueling mast to be independently leak tested.

Abstract: An apparatus for removing and installing a reactor component, such as a circulating pump, by remote operation. The apparatus includes a handling mechanism for transporting various interchangeable containers and tools along a path between a position on top of the suppression pool and a position overlying the reactor component. The handling mechanism has a yoke assembly adapted to receive and support the trunnions of any container or tool, lifting screws for raising and lowering the yoke assembly and an arcuate rack mounted on the shield wall for rotating the yoke assembly around the circumference of the shield wall. A transition collar is latched onto the pump pressure housing. The transition collar has a valve at the top for closing off its interior. Seals arranged between the transition collar and pressure housing to ensure water-tightness.

Abstract: An accelerometer is mounted onto the releasable fuel gripper structure of a refueling machine to form a mechanical interconnection between an accelerometer and a nuclear fuel assembly during removal from a core of a nuclear reactor. An electrical signal is received and processed through an analyzer and recorded corresponding to mechanical vibrations occurring due to the passage of a fluid medium through a porous sidewall defect in a fuel rod of the fuel assembly which is induced by a hydrostatic pressure change on the fuel assembly during upward movement from the reactor core.

Abstract: The guide elements (18) for the internal mast (13) include at least two straight beams (28), on each of which at least two sets of rotatable rollers (19) are mounted which are spaced apart from one another in the axial direction (11) and are on the exterior surface of the external shaft (10) of the fuelling machine. The external shaft (10) includes a through opening (27) for passage of each of the sets of rollers (19) of each of the beams (28), inside the external shaft (10) in order to guide the internal mast (13).

Abstract: A method and an apparatus for testing, repairing or exchanging nozzles of the bottom of a reactor pressure vessel include inserting individual shielding containers into the reactor pressure vessel. Shafts pass through a shielding container and water-filled cartridges can be inserted into the shafts. Tubes for receiving probes of an in-core instrumentation are embedded into bottom plates of the remaining shielding containers and into bottoms of the cartridges. After removing a cartridge, a carrier for working tools can be introduced into the shaft. In this way the radioactive loading is considerably reduced by the probes inside or outside the reactor pressure vessel.

Abstract: An improved system for transferring fuel bundles and control blades between a fuel storage pool and a fuel core of a nuclear reactor. The transfer system includes a carriage which is movable horizontally along a track which is submerged in a transfer pool. The carriage has a slot for receiving interchangeable baskets of different configurations and capacities. One basket is designed to receive a fuel bundle assembly; another basket is designed to receive a control blade. These baskets have the same mounting hardware. The basic construction of the carriage and baskets is aluminum with accessories of stainless steel. Each basket can be hung on the carriage and locked in place with a bolt. Each basket has a bail for handling with existing grapples. When not in use, the baskets are stored and locked in place on a storage rack.

Abstract: A reactor refueling mechanism includes a bridge, a trolley on the bridge, and an elevator on the trolley, with the elevator including a mast with a grapple at the lower end thereof. The bridge spans a reactor core and is rotatable therearound, with the trolley being translatable over the bridge. The elevator is also rotatable on the trolley, and the mast is vertically movable for positioning of the grapple. The combined movement capability of the mechanism allows the shuffling of fuel bundles between cells in the reactor core, and the accurate placement of square fuel bundles in complementary square cells in the core.

Abstract: A part length fuel rod tip and group of tip grasping tools is set forth for the removal, inspection and replacement of part length fuel rods from a fuel bundle having a part length rods interspersed with a majority of conventional full length rods. The part length fuel rod tip includes a longitudinal keyway allowing torque to be exerted on the fuel rod and a horizontal slot enabling grasping of the fuel rod for vertical withdrawal and replacement movement of the fuel rod. The tools include a torque socket for applying high torque forces to the part length rod for unscrewing the rod when the rod becomes stuck at its threaded connection to the lower tie plate, a tip grasping tool for permitting normal unscrewing torque and grasping for vertical withdrawal and replacement, and finally a tool having both high torque and grasping characteristics.

Abstract: The device comprises two winches (12, 12') fastened to the outer surface of a hollow body (2) having a vertical channel (3) in which the load (4) is displaced. Each of the winches (12, 12') comprises two drums (13a, 13b) driven by a common motor (14). The drums (13a, 13b) of a first winch (12) are each arranged opposite a drum of the second winch (12') in relation to the axis of the channel (3). The device comprises two cables (15a, 15b) which are common to two drums located opposite one another around the body (2). The cables (15a, 15b) are wound with their end part on the drums located opposite one another and on their run between the drums pass over deflecting pulleys (16a, 16b), the axis of which is stationary, and over load-supporting pulleys (34a, 34b), the axis of which is movable and accompanies the load. The device ensures that the load is held and displaced in the event of a failure of one of the motor assemblies (14) and in the event of a break of one of the cables.

Abstract: The device comprises, in positions adjacent to the bearing surface (15) of the transportable container (1) on the fixed structure, a first member (16) for plugging the central channel (3) of the container (1), and a second member (17) for plugging the upper end of the well (18). These members are arranged inside a zone of contact of at least one o-ring seal (13) with the bearing surface (15). Each of the plugging members (16, 17) comprises a planar surface arranged, in its closing position, in the planar bearing surface (15) of the container or in the planar bearing surface of the fixed structure, respectively. At least one of the plugging members (16, 17) can move in the axial direction of the well (18) and of the central channel (3) of the container (1) and in a transverse direction perpendicular to the axial direction, between its closing position and its opening position.

Abstract: The grab (1) comprises a tubular body (2) connected to a lifting means and a slide (3) mounted axially movably in the tubular body (2), so as to ensure the actuation of gripping pawls (20) carried by the tubular body (2). The tubular body (2) has a bell-shaped open end part (16), within which the slide (3) is connected to the inner surface of the tubular body over its entire periphery by means of an axially deformable gas-tight elastic member (30). The gripping pawls (20) are arranged within the bell-shaped end part (16) of the tubular element between the elastic member (30) ensuring its closure and its open end (16a). During the introduction of the lower part of the tubular body (2) into the liquid metal (8) in order to carry out the pick-up and displacement of an object (15), gas is trapped inside the bell (16) and forms a reserve, in which the gripping pawls (20) and their control means are located during the pick-up and displacement of the object (15) below the level (8a) of the liquid metal.

Abstract: A refueling mast for a reactor complex includes four generally cylindrical tubes. Each inner tube has vertical grooved tracks formed therein. Each outer tube has a guide roller mounted thereon with grooves which mate with track grooves of a respective track on the adjacent inner tube. Track grooves are cold formed moving a roller die tool up and down each inner tube, while increasing pressure on the incorporated die rollers. This process flattens the inner tube where the tracks are being formed. The grooved tracks and the associated flattening provide the torsional rigidity required on the mast tubes for precise positioning and orientation of fuel elements.

Abstract: A thimble grip fuel assembly handling tool (20) for transporting fully loaded fuel assemblies (52) is disclosed. The tool (20) comprises an elongated mast (23) slidingly disposed within an elongated cylinder (113), the cylinder being of a length less than the mast (23) such that the tool defines a mast fill-up position (126) and a mast full-down position (128). A cage (110) assembly acts to protect the gripping means (32) when the tool is transported in the mast full-up position (126). The gripping means (32) is comprised of a plurality of gripping members (49) which grip the inside diameter of control rod guide thimbles (50). The load path is distributed in the tool such that when the fuel assembly (52) secured to the gripping means (32) is raised, the weight of the fully loaded fuel assembly (52) acts to increase the gripping force on the fuel assembly.

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: A method and an apparatus for controlling a reactor refuelling machine including a plurality of grippers comprised of a plurality of telescopic bars which are telescopically actuatable independently of each other and at least one gripping member mounted to each telescopic bar. A decision is made as to whether the movement of a particular gripper in the Z direction is constrained by a status of the movement of a different gripper. The parallel operation is performed when the movement of the particular gripper in the Z direction is not constrained and when constrained, the particular gripper is placed in condition for waiting.

Abstract: An improved system for repairing and reconstituting a fuel rod assembly in the spent fuel pool of a nuclear power plant is disclosed herein. The improved system includes a height-adjustable elevator and carriage assembly for lifting and inverting a pair a fuel assemblies with their bottom ends adjacent one another, a length-adjustable rod handling tool having a gripper for gripping, lifting, lowering and ungripping a fuel rod, and a dual-axis tool positioner mountable over the bottom ends of the inverted, adjacent fuel assemblies. The tool positioner includes a funnel-shaped tool guide that is movable over the bottom ends of the fuel assemblies for receiving and positioning the gripper of the rod handling tool. The improved system may be adjusted for use in spent fuel pools of substantially different dimensions and water levels without the need for additional parts, and may be operated by only two technicians.

Abstract: An apparatus for loading and unloading a fuel assembly in a nuclear reactor has a bridge and trolley for positioning the fuel assembly and a pair of concentric inner and outer masts with the inner mast vertically movable in the outer mast and guide means to concentrically position the inner mast within the outer mast during such vertical movement. The guide means comprises inner members on the inner mast which cooperate with outer members on the outer mast, the outer members pivotally mounted on a framework on the outer mast for movement towards or away from the inner members. An alignment device is provided to precisely align superimposed outer members and provide vertical alignment therebetween, with an adjustment device provided to aid in the precise alignment of the same.

Abstract: A tool for inserting sleeve blanks in damaged steam-generator tubes of light weight capable of being manipulated by ROSA, a remotely operated service arm. ROSA permits the tool to be attached externally of the channel head of the steam generator.The tool includes a fixed gripper and a moveable gripper. The gripping member of each gripper is a flexible sheet or bladder which conforms readily to the surface being engaged. For insertion, the sleeve blank is mounted on a mandrel. The insertion is carried out by operating the grippers repeatedly through the following cycle until the sleeve blank is inserted into the damaged tube:(a) The moveable gripper is set in the lowermost position.(b) The fixed gripper is open.(c) The moveable gripper engages the sleeving assembly.(d) The moveable gripper raises the sleeving assembly to the uppermost position.(e) The sleeving assembly is engaged by the fixed gripper.(f) The moveable gripper is disengaged from the sleeving assembly.

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: 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: A fast neutron nuclear reactor having a vessel filled with liquid metal and sealed in its upper part by a box slab having a central opening in which is placed a plug-cover-core overhanging the core of the reactor. The central opening is surmounted by a cell containing the handling and storage mechanism for the plug-cover-core and a mechanism for handling the assemblies. The latter can be moved on annular rails and can be collapsed against the wall of the cell, in order to permit the manipulation of the plug-cover-core. A radial passage connects the cell to a transfer station.

Abstract: A liquid metal cooled fast breeder reactor which permits a closer installation of a fuel handling mechanism relative to an upper reactor core structure of the reactor. The fuel handling mechanism has a fuel handling body without a housing, and has a rotational driving device on a rotating plug of a shield plug device of a reactor vessel. The fuel handling mechanism has an aseismatic support extending outwardly from the upper reactor core structure. The fuel handling mechanism is supported, at its upper portion, by the rotational driving device, and secured, at its lower protion, by the aseismatic support.

Abstract: A tool (78) for grasping a multiplicity of nuclear fuel rods (42) to remove them from a nuclear fuel assembly (32) and relocate them, preferably, into a fuel consolidation device (86). The tool has a gripper head (200) reciprocably guided within a shroud (80). A distinct jaw mechanism (216) for grasping each of the multiplicity of fuel rods is carried by a common frame (214) and actuated and controlled by a distinct means (232, 234, 242). A key feature of the gripper head is that each jaw mechanism (216) has an neck portion (244) to offset the actuation means (232, 234) from the moving jaw portion (220). The shroud carries alignment means (82, 206) for precisely orienting the tool relative to a targeted group of rods within the assembly, so that the spacing of the rods is maintained as they are pulled up into the shroud by the gripper head.

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: 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: The invention relates to an apparatus for handling nuclear fuel assemblies, as well as to an assembly for use with such an apparatus.The apparatus comprises a vertically axed guide tube in which is displaced a grapnel, suspended on a flexible connection such as a chain, under the action of a reduction gear. As the grapnel is immobilized in rotation in the guide tube, an assembly is gripped by means of a bayonet system by controlling the rotation of the guide tube-grapnel assembly by a reduction gear. The apparatus can in particular be suspended on the small and/or large rotary plug of a fast neutron nuclear reactor. It can also be used in a handling hod under gas.

Abstract: A fuel rod-loading fixture for expediting the loading of fuel rods in an empty skeleton of a fuel rod assembly is disclosed herein. The fuel rod-loading fixture generally comprises a square array of non-radioactive "dummy" rods which are all connected at their top ends to a top guide plate. When the rods of the fixture are lowered through the rod-receiving apertures of the grids in the fuel assembly skeleton, they effectively obstruct every other set of mutually aligned, rod-receiving apertures in the grids of the skeleton. The top guide plate includes a plurality of apertures which will automatically register with the remaining sets of mutually aligned apertures in the grids, in order that fuel rods may be inserted through the top guide plate and into the remaining sets of apertures in the grids.

Abstract: A tool for positioning a lower guide tube of a reactor for replacement of old split-pin assemblies by new split-pin assemblies. The lower guide tube has an upper and a lower flange and has a length typically between 124 and 150 inches. The split-pin assemblies are secured in counterbores in the lower flange. The tool includes an upper deck and a lower deck. The LGT is suspended from the upper deck from pins which engage holes in the upper flange. With the LGT so suspended the lower flange extends into the lower deck in position to be processed for the replacement. A rotary hydraulic cylinder is provided in the upper deck to rotate the LGT in positions to be processed by other tools involved in the replacement and also so that both of the old split-pin assemblies which are spaced 180.degree. around the periphery of the LGT may be replaced by a single set of robotic tools. A hydraulic lift cylinder is also provided at the upper level to raise the LGT so that it clears the pins when the LGT is to be rotated.