Abstract: A nozzle dam for providing a fluid-tight seal across a primary fluid nozzle in the plenum of a nuclear steam generating vessel includes two fluid-impermeable seals, each comprising a circular three-section foldable seal plate covered with a flexible diaphragm and circumferentially encompassed by an inflatable seal member disposable in frictional sealing engagement with the inner surface of the nozzle. The two seal apparatuses are interconnected by a central tubular coupling coaxial with the nozzle and non-rotatably fixed to each seal, the coupling having a quick-disconnect feature operable from outside the nozzle dam. The coupling provides a conduit for inflation of one of the seals. The two seals are also interconnected by four post assemblies to maintain the seal plates parallel with each other, each post assembly including a cylindrical member pivotally movable between a release position and a supporting position, and provided with a slidable encompassing sleeve to lock it in the supporting position.

Abstract: In the replacement of old split-pin assemblies of a guide tube of a nuclear reactor by new split-pin assemblies, each old split-pin assembly is severed into readily removable fragments by metal disintegration machining apparatus. This apparatus includes a metal disintegration machining tool having an electrode which is guided precisely into arc-disintegrating relationship with the assembly by a glass block in such a way that the assembly is successfully severed into fragments without damaging the guide tube. The electrode is progressively fed into the assembly producing the separation by arc disintegration as it penetrates. The electrode is axially perforated and water under pressure is injected into the arc region through the perforation. A hole is produced in the assembly disintegrating the assembly into a fragment which includes a portion of the nut with a portion of the pin threaded to it and the remaining portion of the pin. The entrance to the hole is a short distance, about 0.

Abstract: An inflatable eddy current inspection probe having a molded central body embedding therein a plurality of eddy current coils and the leads therefore. The central body is expanded at will by introduction of water or air through a pressure hose connected to the central body to produce effective contact between the coils and the inside wall of a tube.

Abstract: An improved, grid-type flow distribution baffle for both providing lateral support for an array of heat exchange tubes and for generating a sludge-sweeping water current within a steam generator is disclosed herein. Generally, the improved baffle comprises a plurality of grid members for defining an array of square, tube-capturing cells, wherein each wall of the cell is closely adjacent and contactable with the side of the tube. Each of the cells is circumscribed by a flange at one of its ends which includes a substantially circular opening for allowing the tube to extend through the cell. The flange includes four flat portions spaced 90.degree. apart for rendering the flange flush with the center portion of each of the square walls which form the cells of the baffle. These flat portions allow the flange to closely circumscribe the tube without coming into contact with it, thereby avoiding "point contact" between the flange and the tube.

Abstract: A model steam generator for simulating the environment inside a nuclear steam generator in order to monitor the condition of the heat exchange tubes of the nuclear steam generator is disclosed herein. The model steam generator includes an electrically-powered thermosyphon heating means for circulating a flow of vapor and condensate through the sample tube in a closed loop. The thermosyphon includes riser tubes which are concentrically disposed within the sample heat exchange tube along a substantial portion of the longitudinal axis thereof for both directing a stream of steam into the inside walls of the heat exchange tubes, and for insulating this flow of steam from the resulting stream of condensate which flows down from the inner walls of the sample tubes. The elimination of the counter-current forces between the stream of steam and the downflowing film of condensate prevents the formation of heat-obstructing ripples of condensate on the inner walls of the sample heat exchange tubes.

Abstract: A method and apparatus for both implementing a braze melt and detecting the time, rate and direction of the braze melt along the longitudinal axis of the tube or sleeve being brazed. Generally, the invention comprises a radiant brazing heater having an electrical resistance coil assembly which serves the dual functions of providing a brazing heat onto a brazing material while simultaneously acting as an eddy current probe. In the preferred embodiment, the electrical resistance coil assembly consists of a pair of coils wound clockwise and counterclockwise, respectively, around the mandrel of the heater assembly. The invention further includes a control circuit having a mechanical relay for alternately switching the two coils of the coil assembly to a heater power source, and to an eddy current generator and detector circuit.

Abstract: A method for detecting radiation emanating from a container comprising the steps of providing shields which define a sector from which radiation can be detected. A sample from which radiation is believed to be emanating is placed in the sector so that radiation emanating from it can strike the detector. The shielding prevents background radiation from striking the detector. Also claimed is an apparatus for detecting radiation emanating from a sample comprising first and second shields and a detector. The shields define a sector from which the detector can detect radiation. Means for supporting the sample is disposed in the sector.

Abstract: A flexural pivot device and method for producing same, wherein rotational motion of a first tubular member relative to a second tubular member is obtained by: forming flexural members from a shape memory alloy into a first shape in the austenitic phase at a first temperature; cooling the flexural members into the martensitic phase at a second temperature; forming the flexural members into a second shape; installing the flexural members between the first and second tubular members; and recreating the first temperature, thus returning the flexural members to the first shape in the austenitic phase and rotating the second tubular member relative to the first tubular member.

Abstract: A light-weight, portable, pipe crawler vehicle includes a four-wheeled chassis, with the sets of wheels along the opposite sides of the chassis being respectively driven by two hydraulic motors. A foldable mast is removably pivotally mounted on the chassis and carries a pneumatic cylinder which, when the mast is in its erected position, forces bearing wheels against the opposite side of the pipe to force the chassis wheels into firm frictional engagement with the pipe so that it can traverse vertical pipe sections while remaining under control. The dimensions of the vehicle are such that when the mast is folded the vehicle will fit through a 16"-diameter manway of a nuclear steam generator vessel. The chassis also carries a three-axis remote manipulator and one or two remotely-controlled video cameras. A position indicator including a star wheel and proximity sensor is disposed for rolling engagement with the pipe to sense distance travelled.

Abstract: A steam generator for use with a nuclear power plant is provided with expandable antivibration bars. The antivibration bars are positioned between columns of tubes in the steam generator and are attached to retaining rings surrounding the bundle of tubes. The antivibration bars are provided with upper and lower bars having mating surfaces comprising series connected inclined planes which allow for relative motion between the upper and lower bars and provide a means to increase the overall thickness across the two bars. Take-up means are provided to guide and assure proper relative motion. The antivibration bars are divided into two elongated lengths each of which forms one of the legs of the "U" shape which the antivibration bar assumes at installation. A double pivot is provided at the connection between the two legs to allow side-by-side positioning of the legs which facilitates installation into an already built steam generator.

Abstract: Both an apparatus and a process for removing fuel rods from spent fuel assemblies is disclosed herein. The apparatus of the invention includes a locking plate having a plurality of tapered holes registrable with the rods of a fuel rod assembly, a plurality of tapered collets, each of which includes a hollow portion for receiving the ends of the fuel rods, and a plurality of hydraulically operated plungers for withdrawing each of the tapered collets into its respective tapered hole in the locking plate, thereby contracting the hollow portion of the collet around its respective rod in gripping engagement. The use of hydraulic plungers causes each of the collets to apply substantially the same gripping force onto its respective fuel rod. Additionally, the apparatus includes a means for confirming whether each of the collets has grippingly engaged its respective rod.

Abstract: A tool is insertable in the narrow annular access space between the cylindrical core barrel and the thermal shield of a nuclear reactor for testing and removing a plug from a flow hole in the core barrel. The tool includes two hydraulically driven jaws which have gripping flanges receivable in a peripheral groove in the plug head for gripping same. The jaws are thin plate-like members and each carries two short pistons having a length less than the thickness of the jaws and hydraulically extendable into engagement with the core barrel for exerting on the jaws and the gripped plug a predetermined force in a plug-removing direction. The jaws are preferably substantially coplanar and carried by a flat arm with the plane of the jaws disposed at a slight angle to the plane of the arm, which angle is selectively variable. Means are provided for pivotally moving the arm about an axis substantially parallel to the axis of the plug.

Abstract: A nuclear reactor fuel assembly grid measuring method and device, including a grid measuring tool mounted on an X, Y, X positioner having a force limiter for each of these three axes and a grid clamping tool. The grid measuring tool is a combination of: a movable, spring-loaded, caliper assembly; a caliper stand assembly; and a base assembly. TV cameras are mounted on the base assembly to allow remote viewing and positioning of the caliper assembly and monitoring of the overall measuring process. An additional separate force limiter is provided near the caliper assembly to prevent excessive force from being applied to the delicate fuel assembly grids. Measurements are taken only after the caliper assembly is positioned upon the grid. Finally, a linear variable differential transformer is associated with the caliper assembly for enhancing accuracy of the measurements.

Abstract: An improved process for brazing a sleeve within a tube is disclosed herein. In the first step of the process, a radial expansion is induced in the tube in a first longitudinal section which does not include the ring of brazing alloy which circumscribes the sleeve. In the second step of the process, the heat source which applies the heat to the tube is gradually translated from a position adjacent to the first longitudinal section of the tube, to a position adjacent to the ring of brazing alloy which circumscribes the sleeve. The resulting thermal expansion which is induced in the length of the tube between the first longitudinal section where the heat source is initially placed, and the ring of brazing alloy avoids the creation of gaps in the resulting braze joint by producing a tapered, stress-absorbing expansion in the tube having a minimum profile in the region where the brazed joint is formed.

Abstract: Both an apparatus and process for providing a coolant flow path in the top former plate of the core of a nuclear reactor are disclosed. The apparatus of the invention generally comprises an elongated tool support member having a tool mounting means for detachably mounting various tools in the vicinity of the top former plate, and a clamp assembly for securing and positioning the tool mounting means over the plate. The apparatus also includes an ultrasonic transducer (or probe) for measuring the thickness of the plate, a rotabroach device having a feed and drive assembly for driving a pilot drill bit and a rotabroach bit toward the top former plate, and a piercing tool for removing the slug formed by the rotabroach bit. In the process of the invention, an alternate coolant flow path is provided in the top former plate by boring a plurality of holes therethrough.

Abstract: A sludge trap, or mud drum, for use in nuclear steam generators includes internal baffles defining multiple laminar flow paths having decreased vertical settling distances. The baffling arrangements take advantage of the diverging nature of circular geometry of sludge traps such that flow path cross-sectional areas are maintained and increased in the direction of flow, to avoid undesired, detrimental flow acceleration; turbulence as well is minimized, thereby to achieve a desired quiescent environment for effective gravitational settlement of sediment and particulate matter.

Abstract: A process for the controlled expansion of a conduit against the walls of a circumscribing structure is disclosed herein. The process generally comprises the steps of applying a radially expansive force to the conduit, while monitoring a variable associated with the elastic and plastic properties of the particular conduit being expanded in order to determine a final swaging force which will complete the expansion process. The process of the invention is particularly useful in eliminating the clearance between heat exchanger tubes and baffle plates in a nuclear reactor, and in sleeving operations wherein an internally inserted sleeve is plastically deformed against a heat exchanger tube in order to affect an interference joint therebetween.

Abstract: An apparatus for expanding a tube against the walls of a circumscribing bore, or a sleeve within a tube to effect an interference joint therebetween, is described herein. The tube expansion apparatus generally comprises a fluid mandrel connected to a hydraulic expansion unit for applying a radially expansive force to the tube or sleeve, and a control circuit electrically connected to the expansion unit and fluidly connected to the mandrel for sensing fluctuations in the pressure of the fluid discharged from the mandrel during the elastic and plastic deformation of the tube or sleeve during the expansion process, computing a final swaging pressure on the basis of these pressure fluctuations, and deactuating the hydraulic expansion unit when this final swaging pressure is attained within the tube or sleeve. The invention is particularly adapted for minimizing or eliminating the clearance between the heat exchange tubes of a nuclear reactor, and the baffle plate bores through which they extend.

Abstract: This invention relates to a method for examining dry material, components of which may have a low level of radioactivity, to sort the radioactive components from the nonradioactive components.

Abstract: A surge suppressing check valve, in its closed condition, closes a fluid passage and separates it into inlet and outlet portions. A cylinder communicates with the outlet portion. A first piston closes the cylinder adjacent to the outlet portion and is axially movable against the urging of a compression spring to enlarge the volume of the outlet portion of the fluid passage for suppressing pressure surges therein. A second piston is provided for pre-loading the bias spring, the pre-loading being selectively variable via a threaded stem and nut connected to the second piston. The first and second pistons are coupled together so that the entire assembly can be removed from the housing. Means are provided for removing fluid from the housing.