Abstract: A method and apparatus for inspecting cylindrically configured pellets for surface defects is disclosed. At least one axially extending linear portion of the peripheral surface of the pellet is optically sensed. A set of discrete digital values representative of the optically sensed linear portion of the pellet surface is generated and the set of digital values is compared to a predetermined standard. Groups of digital values representative of adjacent locations on the surface of the pellet having values greater or less than the predetermined standard are identified. The area of adjacent digital values having a value above the standard, and the area of adjacent digital values having a value below the standard are calculated and compared to a predetermined area. The pellet is rejected when the calculated area exceeds a predetermined area.

Abstract: A fuel rod alignment template and method for loading fuel rods in a nuclear fuel assembly. Front and rear guide plates are provided with a plurality of holes corresponding to cells in the fuel assembly to be loaded. The guide plates are rigidly connected together by connecting rods that extend beyond the front guide plate and are sized to be received in the guide tubes of the fuel assembly. When attached to the fuel assembly with the front guide plate abutting the guide tubes the holes in the guide plates and cells in the grid assemblies of the fuel assembly are in coaxial alignment. This provides positive guidance to the fuel rods as they are inserted into the fuel assembly to prevent mis-tracking and damage to the fuel assembly.

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 grid key and method for keying exterior grid cells in a nuclear fuel assembly. The grid key has a main body portion having first and second ends and is bent at approximately a 45 degree angle near the first end. Two tabs extend outward from the first end at a right angle to the main body portion to define a T-shape. The T-shaped end is inserted into the window of the exterior grid strip such that the top of the T-shape is parallel to the longitudinal axis of the grid assembly. The main body portion is then rotated 90 degrees to position the top of the T-shaped end to be perpendicular to the longitudinal axis of the grid assembly and behind the exterior grid strip. The main body portion is then pulled away from the exterior grid strip in a vertical rotating motion, causing the top of the T-shaped end to pull the exterior grid strip away from the center of the cell defined by the grid assembly.

Abstract: A device for aligning nuclear fuel pellets, for insertion into fuel rods, comprises a vibrating table and a conveyor assembly adapted to receive pellets poured from a container and to deposit them in a single layer on the table. The upper surface of the table is formed with a number of parallel, substantially v-shaped grooves in which the pellets become aligned. The conveyor assembly, which comprises a horizontal traveling belt and an inclined planar slide, is slid along above the table to facilitate the distribution of pellets thereon. An inspection station, adjacent the table, comprises a number of rotating, parallel rollers in columnar-flow communication with the table grooves. Aligned pellets from the table are delivered onto the rollers where they slowly rotate, presenting their circumferential surfaces for visual inspection. A displaceable control member, transversely disposed between the table and the inspection station, controls transfer of pellets therebetween.

Abstract: The device comprises a pole fastened to a handling and lifting apparatus arranged above the pool in which the fuel assembly is placed under water. The pole has at least one lower end part (32), the diameter of which is less than the inside diameter of the blocking sleeve (25). This part (32) is pierced with a central bore (40) and with at least two radial orifices (56), in each of which is located a retention claw (57). A rod (41) sliding in the axial bore (40) makes it possible to control the extraction of the claws. The vertical movement of the pole makes it possible to extract the blocking sleeve (25).

Abstract: The device comprises a pole (31) fastened to a handling and lifting means arranged above the pool in which the fuel assembly is placed underwater. The pole has at least one lower end part (32) or spindle, the diameter of which is less than the inside diameter of the blocking sleeve (25). This part (32) has a spring means (48) for retaining the blocking sleeve in the position engaged on the spindle, and a transversely arranged surface (38) for bearing on part of the sleeve (25), and a means (40) for the vertical movement of the pole (31).

Abstract: In an assembly method for a nuclear fuel assembly, a grid member with springs and a grid member with dimples of the grid are arranged face to face such that grid cells of the grid member with springs and the grid member with dimples communicate with each other. Fuel rods are inserted into the grid cells of the respective grid members while the springs and the dimples are shifted sufficiently relative to each other so as not to contact the fuel rods. Subsequently, the grid members are moved to align the respective grid cells whereby the fuel rods are clamped by contacting with the dimples and springs. The grid members are then connected to each other.

Abstract: A method and apparatus for providing a permanent identification of reactor fuel assemblies with an in-reactor remote readout capability. A bar code type code assemblage is permanently coupled with the upper portion of the fuel assembly which is comprised of alternating components of magnetic and non-magnetic metal such as stainless steel. An active sensor including a magnetic core, excitation winding, and sensor or pick-up winding is employed to interact with the individual code components of the bar code assembly. The latter assembly may be formed as a sequence of rings through which the sensor is passed during a grappling procedure or as a sequence of vertically-oriented bar segments positioned outwardly of the fuel assembly and readable by rotating the fuel assembly before the active sensor.

Abstract: An apparatus for the consolidation of spent nuclear fuel rods within a storage pool uses a robot in conjunction with long reach tools to remove spent fuel rods from a rod assembly and transfer them to a fuel rod consolidation canister. A movable curtain within the canister aligns and locates the rods for most efficient use of space. A tool guide plate enables the long reach rod grasping tool to locate each rod in the fuel cell accurately.

Abstract: Each of the zones of the ferrule (25) comprising a radially projecting deformed part (29) is deformed by inward bending, so as to extract the deformed part (29) from a corresponding cavity (22) of the end block. The locking sleeve (20) is then extracted by exerting a pulling force on this sleeve (20) in the axial direction (ZZ') of the guide tube (4). Preferably, the ferrule (25) consists of cylindrical segments separated by slits arranged along the generatrices of the ferrule (25). A tool (31) is used to fold the segments of the ferrule (25) and to grip these segments so as to extract the locking sleeve (20). Extraction is performed underwater in a fuel storage well.

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

Abstract: The positively acting mechanism comprises a jack (2) with a rod (10) connected, at one of its ends, to a member whose actuation or retention it ensures, and, at its other end, to a thrust piece (16), on which a spring (18) comes to bear, in order to actuate or retain the member. An axle (25) parallel to the rod (10) of the jack is rotatably mounted in a housing (14) fixed relative to the body (3) of the jack (2) and has a threaded part (26) in engagement with a nut (34) forming an engagement fork for the thrust piece (16) of the rod (10). The axle (25) has an end part (30) engaging with a tool allowing the axle (25) to be set in rotation remotely. It is thus possible, in the event of failure of the jack, to rotate the axle (25) and displace the rod (10) of the jack (2) in the direction of release of the mechanism.

Abstract: An inspection system has a pellet diameter inspecting station and an apparatus for transferring pellets past the station. The apparatus includes a stationary support track for aligning and guiding pellets in a row along a linear path, and a transfer mechanism operable through forward and reverse strokes. The transfer mechanism has first and second grippers actuatable between pellet gripping and releasing positions and operable to grip respective rearmost pellets in a first row of pellets to be advanced past the inspecting station and in a second row of pellets previously advanced past the inspecting station. The transfer mechanism is operable to move from an initial position through the forward stroke to advance the pellets at a constant velocity along the linear path.

Abstract: A method of evacuating a container to a vacuum for use in treating radioactive wastes by placing the waste into the container, evacuating, sealing off and thereafter compressing the container, the method being characterized by placing the waste into the container, forming over the waste a filter layer of particulate material fulfilling one of the following requirements: and sealing off and compressing the container.(1) A layer having a thickness of at least 5 mm and formed of a particulate material not smaller than 40 .mu.m to less than 105 .mu.m in mean particle size;(2) A layer having a thickness of D in mm and formed of a particulate material not smaller than 105 .mu.m to not greater than 210 .mu.m in mean particle size d in .mu.m, the thickness D and the mean particle size d having the relationship represented by:D.gtoreq.(20/105).times.d-15;and thereafter aspirating a gas through the filter layer from thereabove to evacuate the container and sealing off and compressing the container.

Abstract: In a method of assembling a nuclear fuel assembly, a deflecting jig is inserted into grid cells in each of a plurality of grids. The diameter of the deflecting jig is enlarged to urge a spring of at least one pair of dimples and spring associated with the grid cell to deflect the spring away from the dimple. A plurality of elongated key members are inserted into the grid cells through a plurality of openings defined at intersections between the straps forming walls of the grid cells. Each key member is rotated about its axis to cause hooks of the key member to project from a wall surface of the strap in a direction opposite to the projecting direction of the springs. The key member is then moved in a direction to engage the hooks with the wall surface of the strap. Urging of the spring by the deflecting jig is released to allow the same to be withdrawn from the grid cells and, subsequently, the fuel rods are inserted into the respective grid cells.

Abstract: A channel box removing apparatus which permits a removal of the channel box from a nuclear fuel assembly while being placed on a fuel rack in a spent fuel storage pool without transferring to a preparation machine. The apparatus includes a pair of pivotally mounted, releasable hooks movable between a latched position where the hooks are in lifting engagement with the undersurfaces of clips provided on a pair of diagonally opposed top corners of the channel box and an unlatched position where the hooks are out of engagement with the associated clips. The apparatus also includes a bail cap mounted thereon for vertical movement and adapted to cooperate with a bail of the fuel assembly to guide the apparatus into an operative position with the fuel assembly during lowering of the apparatus. A locking mechanism is provided for preventing accidental disengagement of the hooks from the associated clips when the channel box is being lifted.

Abstract: A nuclear fuel body provided by doped uranium dioxide grains having kernels of undoped uranium dioxide. The body is produced by mixing single crystal seeds of uranium dioxide with doped uranium dioxide granules. The mixture is compacted and subsequently sintered. Gadolinia is a preferred dopant for the uranium dioxide.

Abstract: A grid key and method for keying exterior grid cells in a nuclear fuel assembly. The grid key has a main body portion having first and second ends and is bent at approximately a 45 degree angle near the first end. Two tabs extend outward from the first end at a right angle to the main body portion to define a T-shape. The T-shape end is inserted into the window of the exterior grid strip such that the top of the T-shape is parallel to the longitudinal axis of the grid assembly. The main body portion is then rotated 90 degrees to position the top of the T-shaped end to be perpendicular to the longitudinal axis of the grid assembly and behind the exterior grid strip. The main body portion is then pulled away from the exterior grid strip in a vertical rotating motion, causing the top of the T-shaped end to pull the exterior grid strip away from the center of the cell defined by the grid assembly.

Abstract: Apparatus for cutting a cruciform shaped radioactive control rod into three separate cut sections, the cruciform shaped radioactive control rod being of the type having four substantially equidistantly spaced sheaths extending from and along a large portion of the length thereof, each sheath containing at least one radioactive rod, and a velocity limiter at one end thereof, the apparatus including a first cutting device for cutting the velocity limiter away from the remainder of the control rod to form a first one of the cut sections; and a second cutting device for simultaneously cutting the remainder of the control rod along the lengthwise direction thereof and substantially transverse to the first cutting device, to form two chevron shaped sections as the remaining two of the cut sections.

Abstract: Molds for making metallic nuclear fuel rods are provided which present reduced risks to the environment by reducing radioactive waste. In one embodiment, the mold is consumable with the fuel rod, and in another embodiment, part of the mold can be re-used. Several molds can be arranged together in a cascaded manner, if desired, or several long cavities can be integrated in a monolithic multiple cavity re-usable mold.

Abstract: Apparatus for loading fuel rods in a desired enrichment pattern includes a carrousel, an elongated fuel rod storage magazine, and a fuel rod verify and feed workstation and a magazine holder and indexing mechanism disposed between the carrousel and the magazine. The carrousel has a plurality of gondolas movable mounted thereon for stocking fuel rods of known enrichments. The magazine defines a matrix of elongated slots open at their forward ends for receiving fuel rods. The workstation defines a fuel rod feed path extending between the carrousel and the magazine and is adapted to receive successively one at a time along the feed path at its upstream end fuel rods from selected ones of the carrousel gondolas.

Abstract: A filling apparatus for the ordered, complete filling of a container with rods, such as spent nuclear fuel rods, in a hexagonally close-packed structure, includes a device for orderly positioning a first row of rods at predetermined positions in a container which has an opening formed in a side thereof opposite the positioning means and an interior with a given width. Two slides disposed one above the other can reach through the opening over the entire given width of the interior of the container. Each of the slides has depressions formed therein defining support teeth. The depressions define openings at predetermined positions for receiving rods of a row. The depressions in one of the slides is offset relative to the depressions in the other of the slides so that the support teeth in one of the slides covers the openings in the other of the slides when the slides are superimposed.

Abstract: The disclosed invention comprises a method for assembling fuel bundles for service in nuclear reactors which minimizes damage to the assembled components of a nature that renders the components susceptible to destructive corrosion in service, and the enhanced product of the improved method. The invention includes the utilization of a temporary protective barrier, such as water soluble sodium silicate or gelatin, intermediate the components during assembly.

Abstract: A drive unit for gripping and rotating a fuel rod during inspection of the fuel rod. A housing has a drive motor mounted at its first end with a spindle rotatably mounted in the housing and directly coupled to the drive motor. A recess at one end of the spindle adjacent the second end of the housing receives a substantially donut shaped rubber bladder. A flanged port that extends radially from the bladder and is in fluid communication with the interior of the bladder provides a means for pressurizing the bladder. This causes radial inward expansion of the bladder for gripping a fuel rod to be inspected.

Abstract: The present invention provides a pellet handling equipment for conveying pellets. The pellet handling equipment is essentially composed of a first roller device, a second roller device, and a pellet supplying device. The first roller device is supported generally horizontal and rotatable about an axis thereof for a rotation in a predetermined direction. The second roller device is disposed parallel and adjacent to the first roller device, supported rotatable about an axis thereof for a rotation in a same direction with the first roller device. The second roller device is provided with a slot formed in a circumferential surface thereof and extending in the axial direction. The slot is capable of receiving each one of the pellets. The pellet supplying device intermittently supplies the pellets to the first and second roller device.

Abstract: An apparatus for the insertion of mutually parallel, elongated fuel rods into an elongated can having a rectangular cross section, a longitudinal direction and a lateral transverse slit formed therein, includes a holder for holding a can. A fuel rod positioning arm has an insertion end for insertion through the slit in the can in an insertion direction at right angles to the longitudinal direction of the can. A support structure is attached to the insertion end of the arm for supporting fuel rods. The support structure has a pivot axis at right angles to the insertion direction of the arm and to the longitudinal direction of the can about which the support structure is pivotable back and forth within a given pivot angle. The support structure has a jacket surface with two fuel rod support surfaces being curved outwardly about the pivot axis and offset alongside one another in the direction of the pivot axis.

Abstract: The invention is directed to an arrangement for transferring irradiated f rods from a trough-shaped receptacle into a canister intended for terminal storage. The canister is docked at a pass-through opening formed in a partition wall of a nuclear facility. The arrangement includes a trough-shaped insert which is movable out of the terminal storage canister while empty and through the pass-through opening into the trough-shaped receptacle whereat it is filled with the irradiated fuel rods and then returned back through the opening and into the terminal storage canister. In this way, and with little effort, a transfer of fuel rods is achieved without components disposed between the receptacle and canister becoming contaminated by radioactive particles.

Abstract: A modular fuel assembly has a plurality of axially stacked subassemblies. The stacked subassemblies includes upper and lower subassemblies which incorporate top and bottom nozzles, and a plurality of intermediate subassemblies disposed between the upper and lower subassemblies. Each subassembly includes a plurality of elongated guide thimble segments, a plurality of fuel rod segments and a pair of support grids mounted to the guide thimble segments and supporting the fuel rod segments. The guide thimble segments of the upper and lower subassemblies are releasably mounted to the respective top and bottom nozzles thereof.

Abstract: A system and a method for removing and consolidating the spent fuel rods of a fuel assembly is disclosed herein. The system comprises a pushing assembly having a push rod for pushing a selected fuel rod out of a fuel assembly, a fuel assembly positioner including an elevator for conveniently positioning a fuel assembly within the spent fuel pool of a nuclear facility, a rod catching grid for preventing the pushed-out fuel rods from falling to the bottom of the pool and a transition cannister for funneling the rods into a consolidated arrangement within a storage cannister. In operation, the push rod is positioned over and engaged against the upper end of a fuel rod to be removed from the assembly. Thus engaged, the push rod is inserted through the cells in the grids of the fuel assembly that surround the selected fuel rod, thereby pushing it out of the fuel assembly. Thus the grid cells are used as an alignment means for the push rod during the rod-pushing operation.

Abstract: A blending/loading system wherein an elongated cylinder or fuel rod is positioned on a turntable underneath a series of hoppers containing the particulates to be blended/loaded. Separate transfer tubes from each hopper are aligned with the cylinder and are subsequently lowered into the cylinder. Upon lowering, the cylinder is rotated and nozzles at the ends of the transfer tubes are activated to discharge, disperse and mix the stored particulates into the rotating cylinder. As the cylinder fills up, the transfer tubes are withdrawn from the rotating cylinder until the desired amount of fill is reached. Afterwards, the nozzles block any additional flow from occurring as they are raised out of the cylinder.

Abstract: A method of inspecting the quality of both ends of nuclear fuel rods and which includes a housing with longitudinally separated slots for receiving X-rays downwardly therethrough to define first and second operating positions so that the forward ends of nuclear fuel rods can be aligned below the first operating position and the rear ends of nuclear fuel rods can be aligned below the second operating position. An endless conveyor belt system, having at least three longitudinally spaced apart cleats mounted thereon to define first and second film cartridge receptacles, is adapted to advance X-ray film cartridges longitudinally through the housing. A table is included for selectively lifting the film cartridges from the belt system to maintain the film cartridges stationary while the conveyor belt system is advanced.

Abstract: Process and holding component for repair of a nuclear reactor fuel assembly spacer support. The holding component is formed from a metal strip, on the free ends of which are introduced elastic projections. After removal of the damaged crosspiece, a holding component partly embracing the fuel rod is locked into a slot of a spacer support by means of its projections.

Abstract: The device comprises a rod (20) on which is mounted a means (22, 24, 25) for the support and displacement of a work tool which is movable in an axial direction of the rod (20) and in two directions perpendicular to this axial direction. The tool comprises tongs consisting of two arms which are articulated together about a spindle fixed on the means (22, 24, 25) for support and displacement in a direction parallel to the axis of the rod (20). The tongs comprise end jaws which are capable of gripping a fuel rod. The gripping of the tongs is controlled remotely and the positioning of these tongs on a fuel rod to be removed is checked by means of a video camera (26).

Abstract: Each of cylindrical members composing a fuel spacer of separate cell type is formed at a edge portion thereof with a positioning notch or a positioning projection, which is located just opposite to one of fuel rod supporting projections formed on the inner surface of the cylindrical member. In manufacturing of the fuel spacer, the positioning notches or projections of the cylindrical members are engaged with the positioning projections or recesses formed on fuel spacer assembly jigs for precise and easy positioning of cylindrical members.

Abstract: A vertical cell is provided for receiving a nuclear fuel assembly having a bundle of fuel rods retained at the nodes of a regular lattice and a skeleton formed of two end pieces connected together by tie rods and grids spaced apart along the tie rods. The structure of the cell has a cross-section corresponding to that of the assembly to be received and carries mechanisms for retaining the grids and the lower end piece, and a comb mechanism for holding the rods at their nominal spacing. The comb mechanism comprises at least two sets of combs carried by a frame fixed to the structure. The combs of each set are guided on the frame, and jacks move them towards and away from each other in a direction transversal to the movement of the combs of the other set.

Abstract: Pellet trays bearing rows of fuel pellets of known enrichment concentrations are retrieved from selected storage elevators and successively conveyed to a zone makeup machine. Parallel rows of pellets are raked from each tray and advanced over a longitudinally elongated, grooved loading surface into abutment with a selectively longitudinally positioned stop. A zone makeup carriage makes up the pellet rows to a prescribed, common zone length, which are then weighted and advanced in parallel by a vibratory loader into a plurality of cladding tubes arranged in parallel loading positions by tube handling apparatus. Overall operation is coordinated by a system controller to concurrently load the cladding tubes with multiple pellet zones of varying enrichments and lengths in automated fashion.

Abstract: A modified inspection apparatus for inspecting nuclear fuel pellets for surface defects includes a pellet guide chute assembly extending through an ultrasonic inspection chamber. The guide chute assembly has a support substrate and a pair of elongated plates attached on respective upper adjacent sides of the substrate. The substrate is composed of a pair of elongated wall sections rigidly attached together to have a V-shaped configuration in cross section. The plates are adjustably attached on the substrate wall sections for supporting a nuclear fuel pellet between and on adjacent longitudinal portions of the plates located in the inspection chamber.

Abstract: An end stop is adapted for engaging the sealing plug positioned in the end of a nuclear fuel rod and so as to permit the evacuation of the fuel rod to facilitate girth welding of the plug onto the rod, and to permit pressurization of the fuel rod and an enclosing welding chamber to facilitate the seal welding closure of the axial opening in the end stop. The end stop includes an axial passage extending therethrough having a welding electrode coaxially positioned therein to facilitate the seal welding closure of the fuel rod sealing plug. An air channel extends between the axial passage and an outlet on the surface of the end stop. A one-way valve is positioned in the air channel for permitting the free passage of a gas from the axial passage to the outlet into the welding chamber while precluding passage of a gas in the reverse direction.

Abstract: A method and system for removing fuel rods from a fuel assembly having top and bottom nozzles that are removed and a plurality of grids for uniformly spacing apart the fuel rods is disclosed. The system includes a rod pushing mechanism which pushes a first end of a selected fuel rod such that a second end of the fuel rod extends out of the fuel assembly. The system also includes a removal device adjacent the second end of the selected fuel rod. The removal device engages and pulls the fuel rod completely from the fuel assembly when the second end of the fuel rod extends out of the fuel assembly a distance sufficient to engage the removal device. The method includes the following steps. First, a first end of a selected fuel rod is pushed such that a second end of the fuel rod extends out of the fuel assembly. Then, the second end of the selected fuel rod is engaged with a removal device. Finally, the selected fuel rod is pulled completely from the fuel assembly with the removal device.

Abstract: A capture row storage tray for holding rows of nuclear fuel pellets includes an array of laterally spaced elongated guide members extending parallel to one another, and stiffening members attached to the guide members for mounting them in the array. Pairs of adjacent guide members define elongated channels therebetween which extend parallel to one another. Each channel is open at one end for receiving a plurality of nuclear fuel pellets therethrough. The adjacent guide members of each pair have laterally spaced bottom portions attached to the stiffening members, laterally spaced and converging side portion with inclined surfaces for confining the pellets in the channel and for guiding and supporting the pellets into and at an end-to-end aligned relationship within the channel, and laterally spaced top portions which define an elongated open slot of a width less than the diameter of the pellets for capturing the pellets in the channel.

Abstract: A system and a method for removing and consolidating the spent fuel rods of a fuel assembly is disclosed herein. The sytem comprises a pushing assembly having a push rod for pushing a selected fuel rod out of a fuel assembly, a fuel assembly positioner including an elevator for conveniently positioning a fuel assembly within the spent fuel pool of a nuclear facility, a rod catching grid for preventing the pushed-out fuel rods from falling to the bottom of the pool and a transition cannister for funneling the rods into a consolidated arrangement within a storage cannister. In operation, the push rod is positioned over and engaged against the upper end of a fuel rod to be removed from the assembly. Thus engaged, the push rod is inserted through the cells in the grids of the fuel assembly that surround the selected fuel rod, thereby pushing it out of the fuel assembly. Thus the grid cells are used as an alignment means for the push rod during the rod-pushing operation.

Abstract: A device for compacting a nuclear fuel assembly structure comprises a vertical compacting chamber having a cross-section matching that of the structure, structure guiding means and a jack for longitudinally compressing the structure against a movable member closing one end of the chamber. The compacting chamber is of sufficient length for receiving a non-fractionated structure and is provided, at the end opposite the compacting jack, with a unit movable transversely to the chamber between a position making possible the introduction of a structure and a position in which a reception box equipped with an ejection jack and forming the removable member is aligned with the compacting chamber.

Abstract: A fuel rod directing chamber for compacting an array of fuel rods from an uncompacted array corresponding to the spacing of fuel rods in a fuel rod assembly to a compacted array in which no spacing exists between the individual fuel rods. The chamber is comprised of an elongated funnel containing a plurality of cavities extending longitudinally therethrough. The cavities form a plurality of holes at an entry end of the funnel corresponding in number and array to an array of fuel rods in a fuel rod assembly. The spacing between the cavities decreases along the length of the funnel until no spacing exists between the cavities. By causing fuel rods of a spent nuclear fuel rod assembly to pass through the cavities of the directing chamber, the spacing between the individual rods decreases, thereby reducing the reactivity of the rods, and increasing the density thereof.

Abstract: The fuel rods located in areas of a nuclear reactor core where water jetting damage to the rods can occur are secured together by a clip, in order to change the mass subject to fretting damage. The change of mass changes the amplitude of the induced fuel rod vibration, thus reducing possible fuel rod fretting and/or damage. To repair such damage, the combination of clip(s) and an inert rod are used to replace a damaged fuel rod.

Abstract: To ensure proper registry of nuclear fuel pellets with fuel pins during loading of pellet stacks into the pins, the pellets are guided through a passageway 28 formed with ribs 42 and pins are located in coaxial passageway 30 also formed with ribs 44. The ribs 42, 44 make substantially line contact with the pellets and pins to reduce the risk of jamming, particularly in the case of the pellets, and the inter-rib spaces serve to collect any dust generated from the friable pellets during feed thereof. Instead of ribs, the passageways may be of polygonal cross-section such that the flat faces of the polygon make substantially line contact with the pellets and pins.

Abstract: The zirconium cladding of a coolant-displacement rod of a nuclear reactor is precollapsed in the zirconium oxide stack of pellets which supports the cladding. Current is conducted through the cladding in an atmosphere at reduced pressure containing residual oxygen, to heat the cladding to a temperature at which its yield strength is reduced. Then, while the rod remains at this temperature, it is subjected to isostatic pressure which collapses the cladding uniformly. The formation, by reason of exposure to neutron flux, of a long unsupported gap in the cladding which might be collapsed under the pressure of the coolant is precluded. In addition, the rod retains its symmetry. The outer surface of the cladding is oxidized, facilitating the movement of the rod into its thimbles of the core and improving the resistances of the cladding to reaction with the coolant.

Abstract: An nuclear fuel assembly including an instrumentation tube adapted for insertion of an in-core detector tube and at least two equi-angularly disposed springs for holding the in-core detector tube concentrically within the instrumentation tube to prevent detector tube vibration is related herein. The springs are preferably secured to the inner surface of the instrumentation tube immediately above the bottom nozzle. An extension sleeve may be provided which extends upwardly or downwardly from the bottom nozzle to surroundingly receive the in-core detector tube. This will effectively increase the axial length of the in-core detector tube that is likely to abut the inner surface of the extension sleeve thus rendering the in-core dectector tube less susceptible to wear due to reactor coolant flow induced vibration.

Abstract: The invention relates to a method for handling a fuel element skeleton of an irradiated nuclear reactor fuel element from which the fuel rods have been removed. The fuel element skeleton is placed horizontally in a compacting shaft of a ram-type press in order to obtain a simple and reliable compaction of the skeleton. After the compacting shaft is closed, the fuel element skeleton is compacted against a press base. The compacted fuel element skeleton is pushed out of the compacting shaft and into a transportable transfer shaft. The loaded transfer shaft is removed from the ram-type press and transported away to a transfer loading location.

Abstract: An end plug is welded to a nuclear fuel rod tube by a girth weld having a melt-zone arcuately extending through the tube wall and into the plug, wherein the melt-zone and the end of the tube are separated by a predetermined distance. The distance is chosen such that heat is dissipated from the weld-zone to prevent damage to the rod and to prevent damage to the weld end stop. This weld enables the use of a substantially solid cylindrical end plug having a first end disposed inside the tube, a second end, and a hollow cavity extending to the second end for axially aligning the cylinder and fuel rod with a frictionally engaging weld stop during formation of the girth weld.