Abstract: A fuel bundle surrogate for the irradiation of a target material, having a plurality of tube sheaths, each tube sheath being parallel to a longitudinal center axis of the fuel bundle surrogate, a plurality of end caps, a pair of end plates, wherein the end plates are disposed at opposing ends of the plurality of tube sheaths, and a first target comprised of a first target material suitable for producing the isotope by way of a neutron capture event, wherein the first target is disposed in a first tube sheath, and wherein the first tube sheath of the plurality of tube sheaths comprises an elongated thickened wall portion and a pair of annular end portions, each annular end portion being disposed on a corresponding end of the thickened wall portion and having a wall thickness that is less than a wall thickness of the thickened wall portion.

Abstract: The invention relates to compositions and methods for coating a zirconium alloy (e.g., ceramic-containing) cladding tube for use with fuel rods in a nuclear water reactor. The coating includes an intermediate oxidation resistant layer and a SiC containing layer at least partially deposited on the intermediate oxidation resistant layer. The SiC containing layer can include a plurality of fibers. The SiC containing layer may also be on the outer surface of end plugs. The invention provides improved capability for the zirconium alloy cladding to withstand normal and accident conditions in the nuclear water reactor.

Abstract: A fuel rod and a fuel assembly for light water reactors, in which crack penetration to a fuel cladding tube or an end plug can be prevented, are provided. The fuel rod 10a includes: a cylindrical cladding tube 11 formed of a ceramic base material; a connection 21 formed of the same material as the cladding tube 11; and an end plug 12a having a concave portion 12f of a continuously curved surface shape adapted to house the connection 21. The end plug 12a is formed of the same material as the cladding tube 11. A slanted surface 11a formed at an end portion of the cladding tube 11, and a slanted surface 12d formed at an end portion of the end plug 12a are joined in contact with each other with a metallic joint material 20. The joint is supported by the connection 21.

Abstract: An open end of a cladding tube of a nuclear fuel rod is plugged with an end plug having a main body and a cylindrical bond portion extending from the main body and terminating in a cladding seat with reduced diameter compared with the cylindrical bond portion. The plugging includes clamping the open end of the cladding tube against the cladding seat of the end plug and, while clamping, applying electrical current between the end plug and the open end of the cladding tube so as to force the open end of the cladding tube over the cladding seat and slide over the cylindrical bond portion of the end plug and to generate a resistance weld between a cylindrical bonding surface of the cylindrical bond portion of the end plug and the inside surface of the open end of the cladding tube.

Abstract: A sheathed, annular metal fuel system is described. A metal fuel pin system is described that includes an annular metal nuclear fuel alloy. A sheath may surround the metal nuclear fuel alloy, and a cladding may surround the sheath. A gas plenum may also be present. Mold arrangements and methods of fabrication of the sheathed, annular metal fuel are also described.

Abstract: A method of providing an end-capped tubular ceramic composite for containing nuclear fuel (34) in a nuclear reactor involves the steps of providing a tubular ceramic composite (40), providing at least one end plug (14, 46, 48), applying (42) the at least one end plug material to the ends of the tubular ceramic composite, applying electrodes to the end plug and tubular ceramic composite and applying current in a plasma sintering means (10, 50) to provide a hermetically sealed tube (52). The invention also provides a sealed tube made by this method.

Abstract: Disclosed embodiments include methods of assembling a vented nuclear fission fuel module. Given by way of non-limiting example and not of limitation, an illustrative method of assembling a vented nuclear fission fuel module includes receiving a nuclear fission fuel element capable of generating a gaseous fission product. A valve body is coupled to the nuclear fission fuel element, and the valve body defines a plenum therein for receiving the gaseous fission product. A valve is disposed in communication with the plenum for controllably venting the gaseous fission product from the plenum. A flexible diaphragm is coupled to the valve for moving the valve. A cap is mounted on the valve, and a manipulator extendable to the cap for manipulating the cap is received.

Abstract: A device for measuring and correcting a parallelism error of an upper plug end of a nuclear fuel rod comprising mechanisms for measuring a parallelism error and for correcting said error, and a mechanism for positioning said device on the fuel rod and cooperating with a rack on which the fuel rod is stored, said correction means being arranged opposite the measuring mechanism relative to the location of the fuel rod, in order to allow a measurement of the parallelism error during correction of said error.

Abstract: A rod assembly for a fuel bundle of a nuclear reactor may include an upper end piece, lower end piece and a plurality of rod segments attached between the upper and lower end pieces and to each other so as to form an axial length of the rod assembly. The rod assembly may include an adaptor subassembly provided at given connection points for connecting adjacent rod segments or a given rod segment with one of the upper and lower end pieces. The connection points along the axial length of the rod assembly may be located where the rod assembly contacts a spacer in the fuel bundle. One (or more) of the rod segments may include an irradiation target therein for producing a desired isotope when a fuel bundle containing one (or more) rod assemblies is irradiated in a core of the reactor.

Abstract: The invention pertains to a nuclear fuel assembly in a nuclear water reactor. The fuel assembly includes an array of a plurality of axially extending elongated tubular nuclear fuel elements having first and second closed ends and encapsulating a fissionable material axially along at least a portion of an interior volume thereof and an exterior of at least one of the fuel elements. The fuel elements include a cladding that extends substantially axially between the first and second closed ends. The exterior surface of the cladding is modified to include a surface texture varying axially in a prescribed pattern along at least a portion of an axial length of the cladding. The surface texture includes a plurality of ribs placed parallel to one another and circumferentially around one or more of the fuel elements. Each of the plurality of ribs has a specified height, width, and pitch between each of the plurality of ribs.

Abstract: A guide thimble plug for a nuclear fuel assembly is provided, in which an internal threaded hole is formed through a main body so that the main body is coupled to a bottom nozzle by a screw coupling. An upper insert part is formed in the upper end of the main body. The upper insert part is inserted into a shock absorption tube. A thermal deformation prevention part is formed on the main body below the upper insert part and is recessed inward from the outer surface of the main body such that, when the main body is coupled to the guide thimble, a gap is defined between the thermal deformation prevention part and the guide thimble. The guide thimble and the shock absorption tube can be reliably fastened to the bottom nozzle, and thermal deformation of the guide thimble can be minimized.

Abstract: A nuclear fuel element for use in water-cooled nuclear power reactors. The fuel element includes a multilayered silicon carbide cladding tube. The multilayered silicon carbide cladding tube preferably includes an inner layer and a central layer. Also, in one embodiment, the ends further include hermetically sealed end caps. The cladding tube is sized to receive a stack of individual fissionable fuel pellets. In one embodiment, the fuel pellets comprise a mixture of thorium oxide and plutonium oxide.

Abstract: Illustrative embodiments provide a nuclear fission reactor, a vented nuclear fission fuel module, methods therefor and a vented nuclear fission fuel module system.

Abstract: An open end of a cladding tube of a nuclear fuel rod is plugged with an end plug having a main body and a cylindrical bond portion extending from the main body and terminating in a cladding seat with reduced diameter compared with the cylindrical bond portion. The plugging includes clamping the open end of the cladding tube against the cladding seat of the end plug and, while clamping, applying electrical current between the end plug and the open end of the cladding tube so as to force the open end of the cladding tube over the cladding seat and slide over the cylindrical bond portion of the end plug and to generate a resistance weld between a cylindrical bonding surface of the cylindrical bond portion of the end plug and the inside surface of the open end of the cladding tube.

Abstract: A pedestal plug is sized to fit into a cladding of a nuclear fuel rod. A lower end plug is sized and shaped to plug the lower end of the nuclear fuel rod. One of the pedestal plug and the lower end plug includes a protrusion and the other of the pedestal plug and the lower end plug includes a hollow region into which the protrusion fits. In one embodiment the pedestal plug is a hollow cylindrical pedestal plug and the protrusion is disposed on the lower end plug. The protrusion disposed on the lower end plug suitably press fits into the hollow cylindrical pedestal plug. In a method of assembling a fuel rod of a nuclear reactor, the pedestal plug and the lower end plug are press fit together, and after the press fitting the lower end plug is welded to a cladding of the fuel rod with the pedestal plug disposed inside the cladding.

Abstract: A lower end plug for an annular nuclear fuel rod includes a support with a great slenderness ratio, a coolant inflow part with an inner inflow space and a plurality of inflow holes in a wall thereof so as to interact with the inflow space, coupled to a lower end of the annular nuclear fuel rod at an upper end thereof, and extending from an upper end of the support in a reverse conical shape such that the inflow space interact with an inner channel of the annular nuclear fuel rod, and a coupler extending from a lower end of the support and coupled with a handing tool of the annular nuclear fuel rod. Thus, although a bottoming phenomenon of the annular nuclear fuel rod occurs, the coolant can be supplied to the inner channel of the annular nuclear fuel rod through the inflow holes of the lower end plug.

Abstract: An intermediate end plug assembly for a segmented fuel rod can stably support the fuel rod to the end of its cycle even if an interval between the fuel rods becomes narrow due to application of a dual-cooled fuel rod, and reduce excess vibration induced by flows of interior and exterior channels of the dual-cooled fuel rod for obtaining high burnup and output. To this end, the fuel rod has a segmented structure so as to make its length short. A lower intermediate end plug includes at least one channel hole, through which a coolant flows into an internal channel of the fuel rod, so that a possibility of causing departure from nuclear boiling ratio (DNBR) of the dual-cooled fuel rod is reduced.

Abstract: Illustrative embodiments provide a nuclear fission reactor, a vented nuclear fission fuel module, methods therefor and a vented nuclear fission fuel module system.

Abstract: A terminal end-piece for a fuel assembly of a pressurized water nuclear reactor, the assembly having fuel rods and a skeleton for supporting the fuel rods, the fuel rods extending in a longitudinal direction and being arranged at the nodes of a substantially regular network, the support skeleton comprising two terminal end-pieces and guide tubes that connect the terminal end-pieces, the fuel rods being arranged longitudinally between the terminal end-pieces, characterized in that the end-piece comprises noses for orientating the flow of a coolant fluid of the reactor along the adjacent longitudinal ends of the fuel rods, the noses being arranged in nodes of the substantially regular network in order to be positioned in a longitudinal continuation of at least some of the fuel rods and/or at least some of the guide tubes of the support skeleton.

Abstract: A nuclear fuel element having a thick walled lower section that transitions to a thinner walled upper section with the transition forming an annular interior ledge that supports the fuel pellets spaced above a bottom end plug. The space between the fuel pellets and the bottom end plug forms a gas collection plenum that assures the necessary void volume exists to maintain margin to rod internal pressure limits.

Abstract: A lower and upper end plugs of an annular fuel rod, into and out of which cooling water flows, comprises: a lower end plug including a filter for debris which has a plurality of pins intersecting each other at the proper position of an inner channel main inlet, through-holes into which the pins of the debris filter are fitted, and at least one inner channel auxiliary inlet through which the cooling water flows into a lower inner channel thereof when the inner channel main inlet is blocked by debris, and which has a through-hole shape; and an upper end plug including at least one upper handling groove and hole, into which a fuel rod handling tool is coupled, at a proper position of an inner circumference of the inner channel main outlet in a circumferential direction.

Abstract: A nuclear fission reactor fuel assembly adapted to permit expansion of the nuclear fuel contained therein. The fuel assembly comprises an enclosure having enclosure walls to sealingly enclose a nuclear fuel foam defining a plurality of interconnected open-cell voids or a plurality of closed-cell voids. The voids permit expansion of the foam toward the voids, which expansion may be due to heat generation and/or fission gas release. The voids shrink or reduce in volume as the foam expands. Pressure on the enclosure walls is substantially reduced because the foam expands toward and even into the voids rather than against the enclosure walls. Thus, the voids provide space into which the foam can expand.

Abstract: A fuel assembly (16) for a nuclear reactor contains fuel rods (48) which contain nuclear fuel pellets (62) held in place by a spring means or a like device (64) and end plugs (56,58) where a hollow gas absorber structure (80) is also disposed within the fuel rods (48) where at least one surface of the absorber structure (80) is coated with a catalyst material (83) that absorbs and retains at least one of hydrogen and tritium.

Abstract: A method and device to repair nuclear fuel assembly structural defects in the top nozzle to guide thimble connection, wherein the device includes a repair sleeve comprising tendons configured to deflect to allow establishment of a structural connection between a projection on each tendon and a dimple area of a guide thimble.

Abstract: A method of controlling the criticality of a nuclear fuel cycle facility includes steps of producing a reactor fuel by adding less than 0.1% by weight of gadolinia to a uranium dioxide powder with a uranium enrichment of greater than 5% by weight and controlling the effective neutron multiplication factor of a uranium dioxide system in a step of handling the reactor fuel to be less than or equal to the maximum of the effective neutron multiplication factor of a uranium dioxide system with a uranium enrichment of 5% by weight.

Abstract: A method for installing a locking retainer in a tube to maintain internal components within the tube under compression comprising the steps of: a) providing an elongated retainer spring having large and small diameter sections with the large diameter section of a size for an interference fit with the interior diameter of the tube and the smaller diameter section of a size having a clearance with the interior diameter of the tube; b) inserting a smaller diameter section of an elongated tool into the larger diameter section of the elongated retainer spring; c) engaging a transition between the smaller and larger diameter sections of the tool against a transition between the larger and smaller diameter sections of the elongated retainer spring; d) inserting the combined tool and retainer spring into an open end of the tube containing internal components with an end of the smaller diameter section of the retainer spring entering the tube first; e) advancing the combined tool and retainer spring within the tube to

Abstract: An fuel assembly with a connection between a fuel channel and a lower tie plate to allow the fuel channel to be removed from an internal fuel rod assembly without the necessity of moving interior fuel rods during removal of the fuel channel.

Abstract: A seal arrangement for providing a seal between a nuclear reactor in-core instrument housing and an instrument contained within the housing includes a lower seal assembly surrounding an outer portion of the in-core instrument housing, an upper seal assembly surrounding an outer portion of the in-core instrument, a seal housing enclosing the lower and upper seal assemblies, and lower and upper compression assemblies positioned on respective ends of the seal housing. The compression assemblies each include a drive nut and a compression collar. The compression collars engage and apply an axial load on the seal assemblies to maintain a reliable seal between the seal housing and the outer portion of the in-core instrument housing, and between the seal housing and the outer portion of the in-core instrument.

Abstract: This disclosure describes a method for metallurgically bonding a complete leak-tight enclosure to a matrix-type fuel element penetrated longitudinally by a multiplicity of coolant channels. Coolant tubes containing solid filler pins are disposed in the coolant channels. A leak-tight metal enclosure is then formed about the entire assembly of fuel matrix, coolant tubes and pins. The completely enclosed and sealed assembly is exposed to a high temperature and pressure gas environment to effect a metallurgical bond between all contacting surfaces therein. The ends of the assembly are then machined away to expose the pin ends which are chemically leached from the coolant tubes to leave the coolant tubes with internal coolant passageways. The invention described herein was made in the course of, or under, a contract with the U.S. Atomic Energy Commission.

Abstract: A method of inspecting an operation of sealed closure by welding an end opening of a filling channel axially traversing an upper plug for closing the cladding of a fuel rod for a nuclear reactor, the cladding of the rod containing a plurality of pellets of nuclear fuel stacked in the axial direction of the cladding and two closure plugs, one of the plugs or the upper plug being traversed axially by the channel for filling the cladding of the rod with an inert gas and the sealed closure by welding of the filling channel of the upper plug being carried out after filling the cladding with inert gas, in a filling apparatus, by melting central part of the end of the upper plug adjacent to the opening of the filling channel, this method allowing for inspection of the conditions for implementing and carrying out the sealed closure of the upper plug by welding, efficiently and without extending the time needed for the manufacture of the fuel rod.

Abstract: Before welding, the plug and the sleeve of the fuel rod being in the welding position at the welding station, the sleeve and the plug of the fuel rod are rotated about their common axis with the aid of rotation means, images are taken along the periphery of the fuel element to obtain digitized images, the digitized images are analyzed to determine the position of the joint plane between the sleeve and the plug of the fuel rod, and the rotation of the fuel element is verified. It is deduced whether it is possible to perform the welding or not. If welding is performed, images are taken of the fuel element along the periphery of the fuel element, in the vicinity of a joint line between the sleeve and the plug, to obtain digitized images which are analyzed to check the conformance of a weld made along the joint line.

Abstract: There is provided a nuclear power station primary pump of the type comprising a drive shaft for rotating a wheel, a heat exchanger, a thermal barrier cover comprising a peripheral skirt provided at its base with a circular end wall, and a diffuser comprising a peripheral skirt provided at its base with a rim. The circular end wall co-operates with the base of the heat exchanger to define a bottom chamber for cold water and includes a central bore provided with a succession of circumferential and superposed rings forming a lip seal of the labyrinth type, and a space is formed between the thermal barrier cover and the diffuser to maintain stagnant cooling fluid.

Abstract: A seal arrangement for providing a seal between a nuclear reactor in-core instrument housing and an instrument contained within the housing includes a lower seal assembly surrounding an outer portion of the in-core instrument housing, an upper seal assembly surrounding an outer portion of the in-core instrument, a seal housing enclosing the lower and upper seal assemblies, and lower and upper compression assemblies positioned on respective ends of the seal housing. The compression assemblies each include a drive nut and a compression collar. The compression collars engage and apply an axial load on the seal assemblies to maintain a reliable seal between the seal housing and the outer portion of the in-core instrument housing, and between the seal housing and the outer portion of the in-core instrument.

Abstract: A welded MOX fuel rod having a cladding and an end plug joined by a circumferential weld, the weld bead being designed to affect equivalent masses in both the cladding and end plug.

Abstract: A fuel assembly for a boiling water reactor comprising a plurality of fuel units, stacked on top of each other, each of which comprising a plurality of fuel rods extending vertically between a top tie plate and a bottom tie plate, and means for keeping the fuel elements together. The fuel elements are surrounded by a fuel channel with a substantially square cross section. At least two of the fuel units differ from each other in regard to fuel distribution or free flow area.

Abstract: The present invention relates to a fuel assembly (1) and a method therefor. The fuel assembly is intended for a light-water cooled nuclear reactor and comprises a first and a second locking member (9a, 9b, 10), a plurality of elongated elements (3, 3a) wherein each of the lower ends of the elongated elements is provided with an end plug (3b). The end plug (3b) is arranged guided or locked in an end plate (6) which comprises at least two adjacently disposed plug holes (6b) for receiving one end plug (3b) each. The first locking member (9a, 9b) is made in an end plug (3b) and has a concave shape and the second locking member (10) is arranged slidable in a locking hole (6c) which is adapted to extend between the two adjacently disposed plug holes (6b) and opening out into these. The second locking member (10) is made with a length exceeding the length of the locking hole (6c) and has end surfaces with shapes intended for cooperation with the concave surface of the first locking member (9a, 9b).

Abstract: The present invention relates to a fuel assembly with a substantially square cross section for a light-water reactor. The light-water reactor comprises a plurality of fuel rods (4) extending between a top tie plate (5) and a bottom tie plate (6). A fuel rod (4) comprises a cladding tube (7a) with a first and a second end which surround a column with fissionable material (7b). According to one aspect of the invention, at least one fuel rod (4) is provided with an axial gap (19) in the fissionable material (7b), such that fissionable material (7b) is arranged on both sides of the axial gap (19) in the fuel rod (4).

Abstract: A method for providing a leak-tight metal enclosure to a fuel matrix penetrated by coolant channels, wherein the mutually contacting surfaces of said metal enclosure and said fuel matrix are metallurgically bonded, comprising placing a metal cladding about the lateral surface of said fuel matrix; disposing metal coolant tubes within said coolant channels; placing a perforated header plate having tubular extensions at each end of the fuel matrix from which the coolant tube ends protrude, said coolant tubes passing through said perforated header plate and said tubular extensions and terminating even with the ends of said extensions; welding, under vacuum, said cladding to said header plates, and the ends of said coolant tubes to the ends of said tubular extensions; exposing the assembly comprising the fuel matrix and enclosure to a gas at high temperature and pressure; and machining said header plates to provide a finished fuel element.

Abstract: The present invention relates to a fuel assembly with a substantially square cross section for a light-water reactor. The light-water reactor comprises a plurality of fuel rods extending between a top tie plate and a bottom tie plate. A fuel rod comprises a cladding tube which surrounds a column with fissionable material. According to one aspect of the invention, at least one fuel rod is provided with an axial gap in the fissionable material. Around this axial gap, the mass of the material is greater than the mass of the material in the main part of the cladding tube.

Abstract: A fuel rod for a nuclear reactor includes a metal cladding tube being filled with nuclear fuel and having ends, an outer surface, and a longitudinal axis. A metal seal plug is welded to one of the ends of the cladding tube at a transition point, defining an annular bead disposed on the outer surface of the cladding tube at the transition point. The annular bead has a cylindrical outer jacket surface extending substantially parallel to the longitudinal axis of the cladding tube. The annular bead has material being formed of the metal of the cladding tube and the metal of the seal plug. A welding apparatus for producing the fuel rod includes an electrode having a through bore formed therein for receiving one end of a cladding tube. A counter electrode is displaceable relative to the electrode for holding a seal plug to be welded to the one end of the cladding tube. The electrode has a cylindrical step formed therein at an end of the through bore facing toward the counter electrode.

Abstract: A fuel rod for a light water reactor comprises a cladding tube which comprises a zirconium alloy having a composition including 0.6 to 2.0% by weight of Nb, 0.5 to 1.5% by weight of Sn, 0.05 to 0.3% by weight of Fe, and the balance being Zr and incidental impurities; uranium oxide fuel pellets packed in the cladding tube; and end plugs comprising a zirconium alloy and closing both ends of the cladding tube. The cladding tube is sealed by TIG welding with the end plugs. Grain boundaries in each heat affected zone of the cladding tube, which are adjacent to a bead formed by TIG welding, have structural compositions including 4 to 30% by weight of Nb, and 0.9 to 20% by weight of Fe.

Abstract: A fuel assembly for a boiling water reactor where the fuel assembly during operation is arranged vertically in the core of the reactor. The fuel assembly comprises a plurality of vertical fuel rods (22) arranged in one or more fuel bundles, wherein at least the majority of the fuel rods comprise a stack of fuel pellets (7) surrounded by a cladding tube (8b) and a plenum tube (23) which is connected to the upper part of the cladding tube (8b), the plenum tube having a cross-section area which is smaller than the cross-section area of the cladding tube.

Abstract: In order to reduce the flow resistance of a coolant flowing through a passage in a support plate of a boiling water reactor and entering a transition piece at a lower end of a fuel assembly resting on the support plate, a lower rim of the transition piece forms a conically tapered surface which fits into a corresponding conical counter-surface at an upper edge of the passage. The lower rim of the transition piece forms a circular inlet which is concentric with the passage and has a size equal to or slightly larger than the passage. Fingers protruding laterally into the passage and extending down into the passage are used to center the lower rim within the passage. Additionally, end caps of the fuel rods may be stream-lined and the lower tie plate of the fuel assembly may be spaced apart from an inner surface of a fuel channel by a plurality of ribs which form a plurality of peripheral through holes on each of the four inner surfaces of the rectangular-shaped fuel channel.

Abstract: A fuel rod for a light water reactor comprises a cladding tube which comprises a zirconium alloy having a composition including 0.6 to 2.0% by weight of Nb, 0.5 to 1.5% by weight of Sn, 0.05 to 0.3% by weight of Fe, and the balance being Zr and incidental impurities; uranium oxide fuel pellets packed in the cladding tube; and end plugs closing both ends of the cladding tube. The cladding tube is sealed by TIG welding with the end plugs. Precipitates having grain diameters of 0.01 to 0.5 .mu.m and comprise intermetallic compounds containing Zr, Nb and Fe are present at grain boundaries in the structure of heat affected zones of the cladding tube, the heat affected zone being adjacent to a bead formed by TIG welding.

Abstract: A fuel assembly for a boiling water reactor comprises a plurality of first full-length fuel rods arranged in an orthogonal lattice, wherein each fuel rod is included in two rows of fuel rods perpendicular to each other, and a number of second fuel rods arranged in parallel with the first fuel rods and having the length considerably smaller than the length of the first fuel rods. The second fuel rods are arranged in the lower part of the fuel assembly in the space which is formed between a number of first fuel rods located adjacent to each other, that is, in a position which does not belong to the orthogonal lattice.

Abstract: End plugs for nuclear fuel rods are provided with a spot weld along the interior end face of the end plugs to seal any streamer openings or passages along the axis of the end plugs, thereby maintaining the fuel rods sealed at its opposite ends. The spot welds are applied by an automated laser welding system in which pallets of end plugs are supported on X-Y positioning tables below a laser movable in a vertical direction. By successively locating the end plugs in the pallet below the laser, the spot welds are formed along the axis of the end plugs and along the interior faces thereof sealing the end plugs.

Abstract: In order to support a shroud against bending, shear, stress and torsion, straps which are preferably formed of the same material as the shroud, are placed in strategic positions with respect to cracks or the like type of weaknesses which have been detected, and fastened in place using a suitable fastening technique. In the preferred embodiments of the invention holes a formed using an EDM technique and bolt units which have an expanding portion are inserted into the holes, torqued and expanded in a manner which fastens the strap to the shroud. Welding and the like type of fastening techniques are not excluded and may used alternatively or in combination with the bolting technique as required.

Abstract: A fluid tight mechanical clamp for creating a compressed graphite seal between a resistance temperature detector nozzle and a NSSS piping hot or cold leg pipe is provided which includes a split graphite seal ring, a peripheral seal back-up ring, a split load sleeve to axially compress and radially expand the split seal ring, a reactor plate and load ring with bolts to drive the load sleeve and compress the seal, and a blowout retainer to prevent the nozzle from blowing out of its seat in the pipe wall in the event of a weld failure. Extensive welding procedures to repair nozzle leaks are thus eliminated.

Abstract: In a fuel bundle assembly for a nuclear reactor wherein a plurality of fuel rods and tie rods extend between upper and lower tie plates and wherein some of the fuel rods are partial length fuel rods extending between the lower tie plate and a spacer located between the upper and lower tie plates, an improved end plug is provided for at least each of the partial length fuel rods, each end plug secured between a respective partial length fuel rod and the lower tie plate. The end plug includes an upper portion constructed of a first alloy material and including an exterior fuel rod receiving surface and a tapped hole in a lower end thereof, and a lower portion constructed of a second alloy material and including upper and lower threaded sections, the upper threaded section receivable within the tapped hole and the lower threaded section receivable within a tapped hole in the lower tie plate. The threaded end plug may be used with full length fuel rods as well as bundle tie rods.

Abstract: The girth welds joining the end plugs and the hollow tubes of nuclear fuel rods are inspected automatically using a technique that averages reflectance values, compares the reflectance values to standards defined as proportions of the average, and counts adjacent pixels outside the standards to analyze for defects exceeding a minimum defect size. The minimum defect size is checked by counting the adjacent pixels in mutually perpendicular directions, such as rows and columns in the collected matrix of pixel data. The maximum count in the two directions can be different, for profiling the maximum acceptable defect as to the direction of its extension relative to the tube and/or weld. Tubes are inspected prior to surface treatments that may conceal defects.