Abstract: A lifting support for a boiling water reactor nuclear fuel assembly comprising a grappling head configured to allow attachment to a lifting device, a body with an upper end and a lower end, the upper end connected to the grappling head, the body configured to be inserted into a water channel of a boiling water reactor nuclear fuel assembly, and an end connected to the lower end, the end configured to be accepted by the nuclear fuel assembly.

Abstract: According to the method, a reactor core is shut down during the operation cycle. One or more fuel bundles of the reactor core are then moved to new positions within the reactor core to increase a total energy, output of the reactor core as compared to continuing operation of the reactor core without the shutting down and moving steps.

Abstract: An apparatus, transfer cask, system, and method for defueling a nuclear reactor and transferring spent nuclear fuel from a spent nuclear fuel to a storage cask for long terms storage. In one aspect, the invention is an apparatus for use in transferring a canister of spent nuclear fuel from a transfer cask to a storage cask, the apparatus comprising a radiation absorbing shield surrounding a portion of a hole through which the canister can pass; means for securing the apparatus to the top surface of the storage cask; means for securing the bottom surface of the transfer cask to the apparatus; wherein the transfer cask securing means and the storage cask securing means are positioned on the apparatus so that when the apparatus is secured to both the transfer cask and the storage cask, the cavity of the transfer cask, the hole, and the cavity of the storage cask are substantially aligned; and means for moving the bottom lid in a horizontal direction once the bottom lid is unfastened from the bottom surface.

Abstract: The invention comprises an apparatus to repair a fuel assembly to accomplish a load lift comprising a main body, an upper section, a connection configured between the main body and the upper section and a lower section connected to the main body. The invention also comprises an inner adjusting body with a top and a bottom wherein a mandrel is connected to the bottom, the mandrel configured to actuate a holding body upon actuation of the inner adjusting body, the inner adjusting body positioned inside the upper section, the main body and the lower section and an actuator connected to the upper section, the actuator configured to actuate the inner adjusting body.

Abstract: An apparatus and method for maximizing the radiation shielding for spent nuclear fuel during cask transfer procedures. In one aspect, the method comprises submersing an apparatus having a jacket and a cavity for receiving spent nuclear fuel into a pool, wherein the jacket is empty and hermetically sealed; placing spent nuclear fuel into the cavity of the apparatus; lifting the apparatus from the pool; placing the apparatus in a staging area; filling the jacket with neutron absorbing liquid; draining the pool water from the cavity; and lifting the apparatus from the staging area.

Abstract: A control rod/fuel support grapple is provided which is capable of pulling up simultaneously a control rod and a fuel support from a reactor and also uncoupling the control rod and control rod drive mechanism. The control rod/fuel support grapple comprises a control rod holding unit for holding a control rod's hoist handle, a fuel support holding unit for holding a fuel support, and a coupling releasing unit or uncoupling the control rod and the control rod drive mechanism, coupled by virtue of a spud coupling. These three units are attached to a main body frame which is lowered into a reactor pressure vessel.

Abstract: The extraction tool includes an inner rod pivotally mounting at its distal end a pair of collet sections having mechanical clamping jaws. An outer tube may be advanced and retracted axially relative to the inner rod by a locking tube nut threaded on a sleeve forming part of the inner rod. The inner rod and outer tube are non-rotationally engaged with one another. By axially displacing the outer tube relative to the inner rod, the collet sections are movable between collet-open and closed positions such that the jaws of the collet can respectively grasp and release the barbed end of the end plug of the fuel rod.

Abstract: A transfer device for moving a poison rod assembly between fuel cells in a nuclear fuel storage facility, where the poison rod assembly has a plurality of poison rods depending from a web. The transfer device includes a frame assembly, a poison rod assembly lifting assembly, which is moveable between an upper position and a lower position, a plurality of comb assemblies. The comb assemblies are slidably mounted on the frame so that the comb assemblies slide between an open position and a closed position as the lifting assembly moves from its lower position to its upper position.

Abstract: Methods and apparatus for moving fuel bundles in a reactor pressure vessel (RPV) of a nuclear reactor are described. In one embodiment of the apparatus, a support tube facilitates the positioning of a multiple channeled magazine within the RPV, especially at locations adjacent fuel bundles. In the one embodiment, the support tube extends in the reactor pressure vessel into the area above the top guide. A magazine assembly is coupled to the support tube, and includes a magazine having a plurality of fuel bundle receiving channels. The magazine extends from the support tube so that it is adjacent the fuel bundles and the top guide. Grapples extend through the magazine channels, engage the fuel bundles, and retract the bundles into the magazine channels. The magazine and support tube, and thus the bundles, are then moved.

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 fuel assembly locator for guiding and inserting nuclear fuel assemblies into a grid plate of a reactor vessel during reload. In the preferred embodiment, the fuel assembly locator includes a plurality of generally trapezoidal guides each having a multiplicity of serially increasing tiered slope regions for gradually directing the fuel assembly precisely into a grid plate opening. The increasing slope regions allow greater positional tolerance between the exterior of the fuel assembly and the interior opening of the grid plate opening initially, thus requiring less time and precision to align the fuel assembly with respect to the grid plate opening. The tolerance then gradually decreases since the slope of each successive tier is greater than the previous tier, thus precisely directing the fuel assembly into alignment with the grid plate opening for insertion therein.

Abstract: The present invention is used in fuel handling for lifting of fuel assemblies and/or control rods out of/into a reactor vessel in a nuclear reactor. The reactor vessel comprises a reactor core with a plurality of fuel assemblies and control rods. A fuel pool is arranged adjacent the reactor vessel. A cassette comprising a plurality of storage positions for fuel assemblies and/or control rods is arranged near the reactor core, whereupon fuel assemblies and/or control rods are lifted out of the reactor core and arranged in the cassette. The cassette is then transported to the fuel pool for temporary storage.

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: The guiding device comprises a body, the size of which corresponds to that of a fuel assembly, intended to rest on the lower core plate (20), equipped with holding means intended to be grasped by an assembly-handling machine, extended downwards by means (18) for positioning it on the lower core plate at an assembly location adjacent to the one intended to receive the assembly to be guided, and two wings (30) carried by the bottom part of the body, forming an angle of 90.degree. in a horizontal plane, each one having an inclined guide face (32) ending at the bottom above the location intended to receive the assembly when the device is in place. Each wing (30) can be retracted, starting from a deployed state, towards a position in which it is withdrawn within the horizontal size of the body.

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: 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 vent tube (66) and housing nut (62) replace the original housing plug (52) on a pressurized water nuclear reactor. The vent tube engages the installed vent stem (38) cross-slot (48) with a cross-shaped projection (70). During operation, the vent tube (66) is pushed down to engage the vent stem (38) and rotated to allow vented air to travel through stem (38) and tube (66). After venting, the vent stem is rotated back and tightened. The invention provides visual indication of a leaking ball (32) since any leakage lifts vent tube (66). Time required for venting is reduced and no removal of installed ball seal (32,34), a proven primary seal, is required.

Abstract: A removable and reusable cap for fuel rod ends to prevent grid damage during loading permits fuel end configurations to match utility's special tooling for fuel assembly repair and reconstitution. The elastomeric transitory fuel rod guidance ends expand over a flange and temporarily snap into place in a groove in the fuel rod end to provide a tapered guiding surface.

Abstract: A method of removing bow in a nuclear fuel assembly is disclosed. The fuel assembly has top and bottom ends fittings and a plurality of longitudinally extending thimble tube members interconnecting top and bottom end fittings. At least two transverse fuel rod support grids are axially spaced along the thimble tube members. A plurality of fuel rods are transversely spaced and supported by the fuel rod support grids. In one embodiment, a weight of known magnitude is secured on the bottom end fitting and the fuel assembly is raised with the weight secured thereon so that the weight exerts a downward force on the fuel assembly for straightening the fuel assembly and eliminating compressive stresses within the fuel assembly. In another embodiment, the bottom end fitting is secured onto the upender used for transporting fuel assemblies into and out of the containment building and the fuel assembly is pulled for straightening the fuel assembly and eliminating compressive stresses within the fuel assembly.

Abstract: A permanent pool seal and neutron shield 30 for providing an effective water barrier over the annular space 28 between a nuclear reactor vessel flange 24 and a surrounding annular ledge 22 includes annular deck sections 32 supported on spaced ribs 46.Flexible membranes 50,52 on the deck section peripheries accommodate relative movement. Openings 42, each with a removable plug structure which includes cover 44 and tapered can 60, provide vessel cavity 14 with ventilation and maintenance access. All cans 60 and similar containers 56 and 59 under the deck structure and flange 24 contain a shielding material 58 in the form of a boron-containing concrete. Supported below the cans is refractory insulating material 54.

Abstract: An end cap is mounted on a fuel rod gripper to cover the end portions of fingers thereon to minimize impacts with grid cell dimples. The fingers are defined by circumferentially-spaced and longitudinally-extending slots in the gripper which permit the finger end portions to radially expand and retract between corresponding expanded and collapsed conditions. The end cap includes a body having a forward camming portion and a rearward mounting portion. The rearward mounting portion is hollow and configured to fit over and cover the end portions of the gripper fingers with the forward camming portion extending forwardly thereof. Also, circumferentially-spaced and longitudinally-extending attachment flutes are disposed internally of the hollow mounting portion of the body and project radially inwardly therefrom.

Abstract: An apparatus is used for cutting guide tubes of a nuclear fuel assembly below an end-piece and removing the end-piece. The apparatus includes a mount which may be removably locked and centered on the end-piece. Cutting tools insertable in the guide tubes each include a hollow shaft whose end part is split by longitudinal slits into radially expandable fingers each having a cutting edge. A stem movable axially along each shaft cooperates therewith for spreading the fingers out radially and retracting them. The shafts are mounted for rotation on a plate which is vertically movable with respect to the mount by a jack and carries a motor for simultaneously rotating all shafts. The shafts are carried by an expansion unit movable vertically with respect to the plate by a jack and including the stems. A method for separating the end-piece with the apparatus is also described.

Abstract: Waste material is passed from a cell 10 through a port 12 into drum 48 which has a mouth 49 with a removable lid 54. A port door 28 includes an electromagnet 54a to hold the lid to the door 28 and both are moved into the cell to allow loading of the drum and after re-closure of door and lid swaging tools 34 operate to deform the lid to form one or more lips which engage under the margin around mouth 49 to resist separation of the lid from the drum.Seals 30, 32, 52 are provided.

Abstract: An end cap is mounted on a fuel rod gripper to cover the end portions of fingers thereon to minimize impacts with grid cell dimples. The fingers are defined by circumferentially-spaced and longitudinally-extending slots in the gripper which permit the finger end portions to radially expand and retract between corresponding expanded and collapsed conditions. The end cap includes a body having a forward camming portion and a rearward mounting portion. The rearward mounting portion is hollow and configured to fit over and cover the end portions of the gripper fingers with the forward camming portion extending forwardly thereof. Also, circumferentially-spaced and longitudinally-extending attachment flutes are dispsoed internally of the hollow mounting portion of the body and project radially inwardly therefrom.

Abstract: A robotic system for remote underwater withdrawal of the fuel rods from fuel modules of a light water breeder reactor includes a collet/grapple assembly for gripping and removing fuel rods in each module, which is positioned by use of a winch and a radial support means attached to a vertical support tube which is mounted over the fuel module. A programmable logic controller in conjunction with a microcomputer, provides control for the accurate positioning and pulling force of the rod grapple assembly. Closed circuit television cameras are provided which aid in operator interface with the robotic system.

Abstract: A nuclear reactor includes a reactor vessel, a reactor core disposed within the vessel and including fuel rods, a primary cooling system disposed in the vessel and including a steam generator and a pump and a poison tank disposed within the vessel and containing high concentration boric acid solution. The poison tank surrounds the reactor core, and the steam generator surrounds a portion of the poison tank.

Abstract: A diverter assembly for diverting a pneumatically conveyed holder for a radioactive material between a central conveying tube and one of a plurality of radially offset conveying tubes includes an airtight container. A diverter tube having an offset end is suitably mounted in the container for rotation. A rotary seal seals one end of the diverter tube during and after rotation of the diverter tube while a spring biased seal seals the other end of the diverter tube which mvoes between various offset conveying tubes. An indexing device rotatably indexes the diverter tube and this indexing device is driven by a suitable drive. The indexing mechanism is preferably a geneva-type mechanism to provide a locking of the diverter tube in place.

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: Method and apparatus for assisting the loading of a reactor core with new and/or irradiated elongated fuel assemblies which includes inserting a fuel assembly with a fuel assembly carrier from a storage pit into a grid position of a reactor core with a refueling machine having propelling equipment, supplying an actual position of the fuel assembly carrier to the propelling equipment of the refueling machine during movement of the refueling machine between the storage pit and the reactor vessel, comparing the actual position of the fuel assembly carrier with a desired position of the fuel assembly carrier to find a deviation, and carrying out a correction of the deviation in the travelling movement of the refueling machine based upon the comparison.

Abstract: A machine for handling nuclear fuel assemblies includes a horizontally movable platform having a vertical telescopic mast whose lower part has a gripper for gripping the upper end piece of the assembly. The mast has several vertical rigid elements ending with segments which bear laterally each on a face of the lower part of the assembly to be inserted. The shoes are independently retractable. They index and center the assembly during reloading already irradiated assemblies. The machine may be used for reloading fuel assemblies into a nuclear reactor.

Abstract: A pressurized water nuclear reactor has a reactor vessel arranged in a pool, which is filled with a neutron absorbing liquid, for example borated water. The reactor vessel is closed except for tubes connecting it with a tray above it. The coolant in the circuit rises from the vessel to the tray, gives up its heat by flashing, and flows back to the bottom of the vessel, driven by natural circulation. The tray is separated from the pool by a vapor-filled bell, which surrounds it. In the bell the vapor gives up its useful heat to a condenser. The relatively low boron content of the cooling circuit, compared to the pool, is achieved by continuous dilution of the condensate from vapor additionally generated out of the pool water. The dilution process is an equilibrium with continuous inflow of the pool water. The inflow is automatically controlled by the pool level, which rises when the pool water is pressed out from below the bell by overproduction of vapor.

Abstract: A swing gate closure assembly for nuclear reactor tipoff assembly wherein the swing gate is cammed open by a fuel element or spacer but is reliably closed at a desired closing rate primarily by hydraulic forces in the absence of a fuel charge.

Abstract: Apparatus for transferring components, particularly rod control cluster elements for a nuclear reactor, to and from containers, particularly fuel assemblies, with the aid of a movable carriage containing compartments for receiving at least one fuel assembly and at least one rod control cluster element. The carriage is mounted on tracks and carries an abutment member arranged to cooperate with stops which delimit respective positions of the carriage along the tracks. When the carriage is at least in some of its positions, a respective compartment is located directly below a vertically movable gripper which is operable for gripping a rod control cluster element. In order to allow the carriage to have more than two positions, there is provided a movable stop which can be lowered to permit the carriage abutment member to move therepast and raised to be contacted by the abutment member.

Abstract: For safety in storage and transport of nuclear fuel elements outside a nuclear reactor core, they are provided with a coating of a neutron-absorbing substance from a liquid phase, e.g. by immersion, spraying or pouring, utilizing a melt, a solution or immersion so that the possibility of critical mass attainment is eliminated or minimized.

Abstract: For safety in storage and transport of nuclear fuel elements outside a nuclear reactor core, they are provided with a coating of a neutron-absorbing substance from a liquid phase, e.g. by immersion, spraying or pouring, utilizing a melt, a solution or immersion so that the possibility of critical mass attainment is eliminated or minimized.

Abstract: Apparatus and process for supervising and controlling the operations of loading and unloading of fuel of a nuclear reactor comprising an information processor 30 formed from several units. A treatment unit 31 receives control signals giving notably the position, the speed, the load of machines 7 and 16 operating the loadings and unloadings of groups in the core 2, the reactor pool 3, and the spent fuel pit 14. A programmable unit 34 furnishes command signals, previously recorded, representing the loading sequence.

Abstract: A closure for an inclined duct having an open upper end and defining downwardly extending passageway. The closure includes a cap for sealing engagement with the open upper end of the duct. Associated with the cap are an array of vertically aligned plug members, each of which has a cross-sectional area substantially conforming to the cross-sectional area of the passageway at least adjacent the upper end of the passageway. The plug members are interconnected in a manner to provide for free movement only in the plane in which the duct is inclined. The uppermost plug member is attached to the cap means and the cap means is in turn connected to a hoist means which is located directly over the open end of the duct.

Abstract: An emergency transfer tube closure for a nuclear reactor well comprising an elongated, vertically-extending, U-shaped guide laterally disposed on each side of the transfer tube, a closure plate vertically disposed between the guides having rollers thereon riding within the guides permitting movement of the closure plate downwardly into sealing engagement with the transfer tube under emergency conditions.

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: In accordance with the present invention, use is made of the adjacent vertically arranged fuel bundles which surround the empty core position to be filled with the fuel bundle to be inserted. Such use of the adjacent bundles involves the placement upon the top tie plate of each bundle of a separate and individual centering device, each centering device being of a generally box-like cap configuration and engaging the upper tie plate of each fuel bundle. Preferably, each such centering device includes a pair of tapered dowel pins which engage apertures formed in the upper surface of the fuel assembly tie plate so that lateral forces imposed upon the centering device will be transmitted to the upper end of the fuel bundle assembly that may be bowed into the empty core position.

Abstract: A refueling machine (100) is provided with a latching/unlatching rod (116) which is provided with a hexagonally configured head portion for mated engagement with a hexagonally configured socket (34) defined within a latching/unlatching screw (22) of a fuel assembly (10) whereby the fuel assembly (10) may be securely mechanically connected to the lower core support plate of the reactor internals. The latching/unlatching rod (116) is fixedly connected to a housing (118) which is co-axially disposed within a torque tube (140), the latter of which is fixedly secured to the lower end of a spur gear (130). The spur gear (130) is rotatably engaged with a drive spur gear (148) through means of an idler gear (128), whereby torque is transmitted to the torque tube (140).

Abstract: Fuel handling apparatus for transporting fuel elements into and out of a nuclear reactor and transporting them within the reactor vessel extends through a penetration in the side of the reactor vessel. A lateral transport device carries the fuel elements laterally within the vessel and through the opening in the side of the vessel, and a reversible lifting device raises and lowers the fuel elements. In the preferred embodiment, the lifting device is supported by a pair of pivot arms.

Abstract: A nuclear reactor refueling system for a liquid metal-cooled fast breeder reactor includes a large rotatable plug (18) eccentrically mounted relative to the reactor core (12), and a small rotatable plug (24) mounted within the large plug (18). A fuel handling machine (28) is rotatably mounted upon the small plug (24), and the eccentric mounting of the large plug (18) permits the fuel handling machine (28) to access all areas of the reactor core (12) as well as a fuel transfer station or port (34) located externally of the reactor core barrel (16) yet internally of the reactor pressure vessel. A unique six-fingered star-shaped upper internals structure (36) is eccentrically mounted upon the large plug (18) so as to be concentrically disposed relative to the core (12) when the reactor is in operation yet permitting access to the central-most fuel assemblies (14) of the core (12) as the large rotatable plug (18) is rotated during refueling operations.

Abstract: A tool for removing split pin remnants which remain in anchor bores in the upper core plate of a nuclear reactor vessel after removal of guide tube assemblies therefrom, includes an elongated mast having parallel tubular members with handle apparatus at the upper end thereof and carrying at the lower end thereof a ram platform having an upstanding pin removal member. The ram platform is dimensioned to be lowered through any one of the guide tube seating apertures in the upper core plate. A locating plate mounted on the mast above the ram platform seats in the seating aperture and accurately positions the ram platform below the upper core plate with the pin driving member in registry with the pin bore. A hydraulic cylinder is mounted on the mast above the locating plate and has a piston rod extending through the locating plate and fixedly secured to the ram platform for moving it up and down to drive the pin from the bore. Hydraulic fluid is carried to and from the cylinder through the mast tubes.

Abstract: A crane for use in a nuclear waste handling facility is disclosed. The crane includes a bridge of sufficient transverse dimension to span the width of the area being serviced, a bridge drive for moving the bridge along spaced rails extending longitudinally along opposite sides of the area being serviced, and a crane control cabinet depending from a cantilevered support extending from one end of the bridge. The nuclear waste handling facility includes a stationary radiation barrier extending longitudinally in spaced relationship to one of the rails supporting the crane. The barrier is positioned between the bridge and the crane control cabinet.

Abstract: A latching device for use in nuclear reactors. The device is used to latch outer housing assemblies to the reactor core. The device contains a shear pin which does not break under normal loading imposed by movement of absorber rod assemblies, but which shears when it is desired to remove the housing from the core.

Abstract: Method of loading or unloading or both loading and unloading a nuclear reactor, wherein control rods of cruciform cross section are at least partly withdrawn, each of the control rods being associated with a respective group of four fuel assemblies respectively having elongated duct tubes of rectangular cross section and being disposed in respective corners of a rectangular mesh of a transverse support grid, the duct tubes forming therebetween a gap-shaped intermediate space of cruciform cross section for accommodating a respective one of the control rods of cruciform cross section, which includes, prior to withdrawing a respective control rod associated with the respective group of four fuel assemblies, unloading from the nuclear reactor at least one of the four fuel assemblies of the group thereof, and inserting a support member into the respective mesh so as to fix in the respective corners of the mesh the ends of two diagonally opposed fuel assemblies of the group remaining in the nuclear reactor; and sup

Abstract: Device for the underwater disengagement of a nuclear reactor fuel element from a grapnel with at least two articulated fingers. The device is designed to be placed on the end of a duct for positioning fuel elements and includes jacks for adjusting the relative positions of the device and of the grapnel-fuel element unit and for maintaining these positions, further jacks for unfastening the fingers of the grapnel from the body of the grapnel and still further, jacks for tilting the fingers of the grapnel so as to enable the fingers to release their hold on the fuel element.

Abstract: This system incorporates a uniquely coded longitudinally extending absolute distance standard or code chart. The code chart includes bars and segments of different light reflectivity characteristics which uniquely define every different distance increment along the chart. Preferably the chart is binary coded. A transducer optically detects the code at each different distance measurement increment and converts the code into electrical signals. The electrical signals operatively control a manipulator device which moves along a movement track parallel to the stationarily positioned chart. The transducer includes means for detecting the code at or near the center of each distance measurement increment, rather than at the edges of the distance measurement increments where the code on the chart undergoes transitions. A sample bar extending along the chart defines the distance measurement increments and the points at which the code at or near the center of the distance measurement increments is to be sampled.

Abstract: A pool type nuclear fission reactor has a core, with a plurality of core elements and a redan which confines coolant as a hot pool at a first end of the core separated from a cold pool at a second end of the core by the redan. A fuel handling system for use with such reactors comprises a core element storage basket located outside of the redan in the cold pool. An access passage is formed in the redan with a gate for opening and closing the passage to maintain the temperature differential between the hot pool and the cold pool. A mechanism is provided for opening and closing the gate. A lifting arm is also provided for manipulating the fuel core elements through the access passage between the storage basket and the core when the redan gate is open.