Abstract: A method for electromagnetic ultrasonic conversion includes exerting dynamic-mechanical forces upon particles of an electrically conductive material of a test sample by superimposing quasi-static magnetic and electromagnetic high-frequency fields of a transmission converter for generating ultrasonic vibrations when transmitting. Electrical fields are induced by waves arriving in the test sample resulting in vibrations of the particles of material inductively affecting the fields of a receiver converter when receiving. The excitation of the vibrations when transmitting and the induction of electrical fields when receiving are effected by Lorentz and magnetic forces as well as by magnetostriction forces if the test sample is ferromagnetic. Fill level and bubble formation are monitored in enclosures in the form of containers and pipelines for liquid, by coupling a transmission converter and a receiver converter to an enclosure wall.

Abstract: The present invention obtains enthalpy rise deviations in core power distribution using core exit thermocouples 18 and an inlet temperature detector 20. The enthalpy rise deviations are used to determine control rod position change relative a rod reference position. Because rod position change is linear with respect to enthalpy deviation, the change can be determined from the slope using the deviation. By adding the change to a reference rod position the actual rod position can be determined.

Abstract: An apparatus is disclosed for determining pressurization in a nuclear fuel rod and the like by measuring the increase in diameter of the fuel rod occasioned by the internal pressurization of the rod, and which includes an elongate receiving member having front and rear ends and an axial opening extending therein. A gauge is positioned in the axial opening and is adapted to coaxially surround the fuel rod and then measure an increase in diameter of a fuel rod caused by a pressure increase within the rod. The gauge is formed from a substantially C-shaped bracket having inner and outer surfaces, spaced distal end portions and a more thin medial portion, and with a strain gauge mounted on both the inner and outer medial surfaces. A microprocessor is connected to the strain gauges so that changes in electrical output from the strain gauges can be measured to determine the increase in diameter of the fuel rod upon pressurization of the fuel rod.

Abstract: A device for measuring and remotely checking external dimensions of an external lateral face of a part of a work piece. The device comprises measuring means for measuring the length of the part and including a set of two ultrasonic transducers arranged to transmit and receive ultrasound pulses, a movable support for supporting the transducers, abutting means, first rotation means for rotating the supporting means about an axis parallel to the longitudinal axis of the workpiece, and second rotation means for rotating the supporting means between an initial position where the two transducers are substantially directed along a line perpendicular to the longitudinal axis of the workpiece and two predetermined angular positions symmetrical with respect to the initial position, and means for rectilinearly displacing the movable support for bringing the movable support into and out abutting contact with the lateral face to be measured.

Abstract: Eddy current probe apparatus having an expansible sleeve thereon capable of hydraulically diametrically expanding a tubular member into engagement with an adjacent structure and capable of hydraulically diametrically expanding a tubular sealing member disposed in the tubular member into engagement with the interior wall of the tubular member, which probe is capable also of detecting the location of the structure and the extent of diametrical expansion of the sealing member and tubular member. The apparatus comprises a support body, expansion means sealingly attached to and surrounding the support body for diametrically expanding the tubular member or sealing member, and electromagnetic means connected to the support body for continuously electromagnetically detecting the variations in the electromagnetic characteristics of the tubular member, sealing member, and structure and the extent of diametrical expansion of the tubular member and sealing member.

Abstract: A level sensor system for liquids and liquid slurries utilizes a capacitive probe which extends longitudinally into a liquid or liquid slurry containing vessel, and which may contain inner and outer sensors spaced from each other in an assembly with a flow control screen at its lower end to permit egress of liquid and exclusion of the solid slurry material, thereby enabling both liquid and slurry level to be determined. The capacitance presented by each sensor is converted into a digital output in repetitive cycles having a reference phase, where a reference voltage is generated by charging a reference capacitor while a counter is registering counts and until a pre-determined count is reached, and in a computing phase while counts are accumulated until the capacitance presented by the probe charges to a voltage equal to the reference voltage.

Abstract: An apparatus for the inspection of nuclear reactor fuel rods combined in fuel rod clusters with spaces therebetween in a fuel assembly includes test probes each being disposed at a different respective level along the fuel assembly. Fingers are each part of a respective one of the test probes. Ultrasonic test heads are each disposed on a respective one of the fingers. The test heads are inserted into the spaces between the fuel rods, and the insertion position of each of the test probes is corrected independently of the insertion position of the others of the test probes, before insertion of the test probes.

Abstract: The method consists in separating the worn-out steam generator (1) from the primary circuit, by sectioning the pipes (3, 5) in the vicinity of the steam generator pipework, withdrawing the worn-out steam generator, placing a replacement steam generator in position and welding the pipe work of the replacement steam generator to the primary pipes (3, 5). Topometric measurements are carried out on the replacement generator, on the worn-out steam generator (1) in position in its compartment (11) and in the compartment (11) after the removal of the worn-out generator (1). Comparison of the topometric measurements enables the replacement procedure to be determined, i.e., the number of cuts to be made on the primary pipes (3, 5), the modifications to be made to the supporting and positioning devices (8, 17) and the position of the chamfers for welding the pipes (3, 5) and the pipework of the replacement steam generator.

Abstract: A device for measuring cycles of random reciprocal motion of an object, such as a control valve which moves in discrete movements of varying length between an opened and closed position, includes a cylindrical travel translator member biased within a housing by a coil spring to maintain tension on a cable connecting the travel translator member to the object, so that the travel translator member moves in a direction corresponding to and a distance proportional to that of the object. An elastomeric wheel frictionally engages the travel translator member to rotate a shaft which operates a mechanical counter, and through a cam, a limit switch which generates pulses representative of the random cycles of the object.

Abstract: Refueling apparatus for a nuclear reactor including a bridge and a trolley. The bridge is moveable in tracks along the containment of the pit in which the reactor is immersed in water and the trolley moveable in tracks on the bridge at right angles to the tracks on the bridge. The trolley carries a mast assembly for engaging, raising, lowering a nuclear-reactor component assembly involved in refueling. The mast includes an elongated member for engaging control-rod and thimble plug assembly and a gripper for raising fuel assemblies. The elongated member is moveable upwardly or downwardly.The bridge, trolley and mast assembly each has a pulse generator which produces pulses in accordance with the movement of each. The number of pulses produced when the bridge, trolley or elongated member move to a position at a predetermined distance from a reference position is a measure of the new position of each.

Abstract: A test tool for a reactor vessel level instrumentation system which simulates and verifies the values of input signals applied to the instrumentation system. The test tool includes potentiometers for simulating the signals produced by resistance temperature detectors, switches for simulating pump status and isolator overrange limit signals, a power supply, resistors and potentiometers for simulating temperature hot sensors and a pressure wide range sensor, and potentiometers and resistors for simulating differential pressure cell signals. The invention also includes a switchable meter for verifying the values of the various input signals simulated.

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

Abstract: A Local Power Range Monitor (LPRM) string is employed between BWR fuel assemblies arranged in side-by-side spaced positions. The string has a hollow tube and neutron detectors located therein at spaced axial locations and being adapted to provide local power monitoring information. The hollow string tube is adapted to receive a neutron flux sensitive probe for calibrating the detectors. Each fuel assembly has an outer hollow tubular channel surrounding fuel rods and spacers disposed within and axially along the channel and about the fuel rods. The spacers are composed of a material incapable of producing a localized change in neutron flux. Elements in the form of strips of a neutron absorber material are attached to the exterior of the channel of each fuel assembly at a respective corner thereon and located axially at different known positions therealong and adjacent to the hollow string tube.

Abstract: A fuel assembly grid inspection apparatus includes a precision noncontact measurement device having a source of illumination and a viewing system which define an inspection field of view. The viewing system is adapted to view and record one or more images of an object, such as a fuel assembly grid, located in the field of view to provide information from actual measurements of the grid which can be calculated to determine whether or not it comes within acceptable tolerances of the measurements of a standard grid of the same design. The apparatus also includes a universal fixture adapted to support any one of a variety of grids of different designs within the field of view such that portions of the fixture within the field of view are substantially transparent to the viewing system. The viewing system and the fixture are movable relative to each other in X, Y and Z directions for achieving a complete inspection of all parts of the grid.

Abstract: A method for measuring the filling level of a liquid in a pressure vessel of a boiling-water reactor, includes measuring the pressure difference between a lower subspace and a reference column, determining steam density in an upper subspace from the measured pressure, determining liquid density in the lower subspace, determining the liquid density in the column, subsequently determining the level in the vessel from the liquid densities in the lower subspace and column, from the steam density in the upper subspace and from the pressure difference and from taking into account time-dependent transient alterations of the values of the densities by measuring the pressure change over time in the upper subspace, the power output and the temperature of the liquid in the vessel, determining therefrom the liquid density in the lower subspace and the steam density in the upper subspace with the measured pressure in the steam space and with known dimensions and quantities, and measuring ambient temperature in the vicinit

Abstract: An electromechanical measurement system for acquiring dimensional data from a nuclear fuel assembly includes an underwater measurement assembly, support means for mounting same on the edge of a spent fuel pool, and a control and data acquisition and processing unit. The underwater measurement assembly includes an elongated strongback disposable vertically along a pool wall, adjustment mechanism on a support assembly permitting accurate positioning of the strongback. A support plate carries hydraulic clamps for clamping the top nozzle of a fuel assembly while it is supported from overhead, a clamp carried by the lower end of the strongback being engageable with the bottom nozzle for holding the fuel assembly in a selected orientation with the faces of the top nozzle vertical.

Abstract: A vent system for controlling hydraulically actuated drive means for selectively moving pluralities of rod clusters respectively connected to the plurality of drive means between fully inserted positions within the lower barrel assembly of the vessel in telescoping relationship with fuel rod assemblies contained therein, and a fully withdrawn position. Each drive means responds to the reactor coolant fluid pressure and includes a leakage passage and an outlet channel through which a leakage flow may pass under control of the vent system, the latter comprising a valve arrangement, flow restrictors and a common orifice through which the outlet channels are selectively connected to essentially ambient pressure, for establishing a pressure differential within each drive means producing a net force for moving the drive rods and associated clusters to the withdrawn position at which the drive means mechanically latch the fully withdrawn clusters for mechanically supporting same in the fully withdrawn position.

Abstract: A position sensing mechanism, for use with a nuclear fuel transfer system which employs an underwater cart having a pivotable container to receive fuel assemblies, employs mechanical elements below water and a cable which carries movement of the mechanical elements to a switch assembly at a dry location. The mechanical elements include an anchor element which is affixed to an upender mechanism, which selectively moves the container between horizontal and upended positions when the cart is located at a fuel transfer station, and a feeler mechanism which is displaced by the cart. The feeler mechanism includes a pivotably mounted swing arm and one or more pulleys. The cable is attached to the anchor elements and is guided by the pulleys. The switch assembly includes a further pulley having cams to actuate microswitches when the cable is displaced by the anchor element and feeler mechanism. A temperature compensator is spliced into the cable to keep its length constant despite temperature variations.

Abstract: The specification discloses a boundary detector for locating the boundary between two substances having different thermal absorption characteristics. In one embodiment, the detector monitors the level of a coolant in a vessel in which case the upper surface of the coolant constitutes the detected boundary. An elongate sensor is constructed of a plurality of segments of different material connected end-to-end to form a series of thermocouple junctions. This sensor is disposed across the boundary in the two substances, and a segmented heater cable is used to heat selected ones of the thermocouple junctions. The sensor and the heater cable are electrically insulated by thermally conductive material that will transfer heat to the substances in which the sensor is disposed, and because of this heat transfer, the temperatures of the heated junctions are, in part, dependent upon the substance in which it is located. By monitoring the voltage potential across the sensor, the boundary may be detected and located.

Abstract: Disclosed is a nuclear reactor employing a liquid metal and containing a reactor vessel, and at least one satellite vessel, and a hot and a cold leg connecting means which combine to form a continuous pathway for the flow of the liquid metal between the reactor vessel and the at least one satellite vessel. Each of the hot leg and cold leg connecting means contain a bellows assembly which are readily accessible for repair or replacement without draining the reactor vessel of the liquid metal.

Abstract: An apparatus for an integrated and automated fuel assembly inspection system includes a support base, an elongated fixture, top and bottom carriages and a pedestal. The top carriage is mounted to a pair of tracks on the fixture for vertical movement therealong. The pedestal is mounted on the base and aligned with the top carriage for supporting a nuclear fuel assembly therebetween. The bottom carriage has a central opening adapted to receive the fuel assembly therethrough such that the bottom carriage surrounds all sides of the fuel assembly. Also, the bottom carriage is mounted to the tracks for generally vertical movement along the fixture and the fuel assembly. D.C. stepping motors are mounted on the top and bottom carriages and coupled to a gear track for selectively driving the carriages along the fixture.

Abstract: The invention relates to an apparatus making it possible to measure the position of a moving bar in a non-magnetic guidance enclosure. The bar carries a permanent magnet, whose position is detected by at least one group of magnetometer transducers, arranged along a generatrix of the enclosure. The transducers of the same group are connected so as to form a matrix of n rows and p columns. The exciting windings of the transducers of the same row are connected in series and each row is supplied in turn by a multiplexing circuit. In the same way, the reading windings of the transducers of the same column are connected in parallel and each column is scanned in turn by a multiplexing circuit.

Abstract: A steam generator level measurement system of the type having a reference leg which is kept full of water by a condensation pot, has a separator pot in the connecting line between the condensation pot and the steam phase in the steam generator to remove excess liquid from the steam externally of the steam generator. The separator pot has an expansion chamber which slows down the velocity of the steam/liquid mixture to aid in separation, and a baffle, which directs steam introduced at the top of the chamber on one side of the baffle to flow downward and then upward for discharge on the other side of the baffle to avoid direct liquid penetration into the line connected to the condensate pot.

Abstract: A system for remotely repairing nuclear fuel rod assemblies is disclosed herein. Generally, the system comprises a rod handler for gripping, lifting, lowering and ungripping a selected fuel rod, a work station for securing the nuclear fuel rod assembly to be repaired into a desired location, and a positioner device for laterally positioning the rod handler over a selected rod in the fuel assembly secured within the work station. The rod handler includes a contractable collet for gripping and ungripping a desired fuel rod, and a rod sensor concentrically disposed within the collet for sensing when a rod is in a grippable position. The positioner includes a movable carriage which is slidably mounted onto a frame assembly by means of a pair of rail and bearing mechanisms. The system also includes a microcomputer for controlling the manner in which the positioner positions the rod handler, as well as gripping, lifting, lowering and ungripping motions of the handler itself.

Abstract: A position indication system for detecting the position of an elongated, metallic member which is linearly movable between first and second positions along an axis corresponding to its longitudinal dimension. A sensor is operatively associated with the member for producing a first output signal which corresponds to the position of the member and which fluctuates with changes in the temperature of the member. A temperature monitoring device is operatively associated with the member for monitoring its temperature and for producing a second output signal which varies in direct response to changes in the temperature of the member. A combining circuit is connected to the sensor and to the temperature monitoring device for receiving the first and second output signals and for producing a third output signal which represents the position of the member compensated for changes in temperature of the member.

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 drain recovery system for the condensate feedwater system of a nuclear power plant having condensate pumps for boosting the condensate from a condenser, and feedwater heaters for heating the condensate from the condensate pumps.

Abstract: Position indicating device for producing an indication of the position of a displaceable structure, the device including:a plurality of sensing elements extending along a defined path such that each element is associated with a respective location along the defined path, each element being operative to respond to the presence of a position representing member when the member extends from a starting point to the respective location associated with that element, the elements being coupled into respective pairs of elements, with each pair of elements having an output producing a signal only when a single element of its respective pair is responding to the presence of the member; a plurality of signal producing members each operative for producing a signal representing a predetermined logic state in response to a predetermined input signal; and circuit components operatively connecting the outputs to the signal producing members for causing a signal at each output to produce a predetermined input signal at a corr

Abstract: A combined in-core flux detector and thermocouple assembly for a nuclear reactor composed of an outer tube which is sealed at its upper end; an inner tube disposed within, and extending along the length of, the outer tube; a neutron detector means disposed within the inner tube; an element connected to the neutron detector for displacing the neutron detector along the length of the inner tube; and a plurality of thermocouples disposed outside of the inner tube and enclosed within the outer tube.

Abstract: Device for checking the vertical alignment of the upper and lower internal equipment of a pressurized water nuclear reactor comprising a vertical tubular body (14) onto which are fixed a flange (15) for centering the upper internal equipment on the upper plate (2), a flange (16) for centering on the upper core plate (3) and a lower end member (17) which enables the device (1) to be centered on the lower core plate (4). A metal wire (24) is aligned along the axis of the tubular body (14), its lower part being fixed to the end member (17) and its upper part to a fitting (20) which can move in two horizontal directions at 90.degree.. Electrodes are arranged in the flange (16) around the wire (24), to detect, by virtue of an electrical monitoring circuit (90), contact between the wire (24) and the electrodes when the upper part of the wire is moved by the fitting (20).

Abstract: A gap measurement probe for measuring the gap between a tub and an antivibration bar in a steam generator includes a shaft and first and second sensors mounted on one end of the shaft. Each of the sensors includes a coil form having a first portion fastened to the shaft and having a second C-shaped portion surrounding a portion of the periphery of the shaft. A test coil is mounted on the second C-shaped portion of each of the coil forms and the test coils are arranged such that they extend about different portions of the circumference of the shaft so as to sense different portions of the circumference of the tube when the gap measurement probe is inserted in the tube. The coil forms are flexible and have a circumference which is sufficiently large to press the test coils against the inside of the tube to provide for accurate sensing.

Abstract: In a system for inspecting fuel assembly guide thimbles, an apparatus for handling drag gages insertable within the guide thimbles includes a spider rotatably mounted to an upright support structure and supporting drag gages in a series of angularly-displaced storage positions about the support structure, and a drive operable to rotate the spider relative to the support structure and thereby moving the gages about an endless path to dispose a selected one thereof at a retrieval-and-return station. An elongated track mounted to the support structure extends outwardly above the spider, and a trolley is movable along the track between a remote position overlying a work station containing the fuel assembly to be inspected and a position adjacent to the support structure and overlying the drag gage retrieval-and-return station.

Abstract: With the reactor vessel (1) open and filled with water, and the core assemblies removed, means for measuring alignment (50) and means for measuring clearances (56, 58, 59) are mounted on the upper internal equipment (13). The upper equipment (13) is introduced into the vessel and is deposited on the lower equipment (3). Measurements of alignment are carried out and, if appropriate, the alignment is corrected by moving the upper internal equipment on the lower equipment (8). The clearances of the upper core plate are measured and, if appropriate, the upper internal equipment (13) is moved as a function of these measurements. The clearances around the centering and alignment pins are measured and adapters are machined and then fixed to the upper internal equipment (13) to reduce the clearances around the pins to a low, predetermined value. The invention also relates to the device for measuring and adapting the position of the internal equipment.

Abstract: The overflow in the secondary of a steam generator of a nuclear-reactor plant, which occurs when one or more primary tubes conducting the coolant are ruptured, is controlled. The secondary of the steam generator, which contains the water that is converted to steam, is connected through valves to the pressurizer relief tank. The level of the liquid in the shell is monitored. An alarm is sounded when the level of the liquid in the generator reaches a predetermined height alerting the operator. When the level reaches a greater height, the valves are opened and the liquid in the shell is discharged into the pressurizer relief tank. The liquid in the tank is discharged into the containment sump when a disc is ruptured. The time taken after the rupture is 30 minutes as mandated by safety regulations. If, after the liquid in the shell reaches the level at which the valves are opened, the level drops to a height at which steam may be injected into the pressurizer relief tank, the valves are automatically closed.

Abstract: Installation for electric connection of devices placed inside the containment of a PWR, comprising a first cable associated with each electric device, extending from the device and connected to a fixed connector installed above the cover of the reactor vessel. A second cable is connected to the connector and to a connector fixed to a plate remote from the reactor vessel. Each second cable is formed from several sections including a first section for connection to the fixed connector above the cover and to a lead-in connector at the end of a leak tight conduit installed horizontally above the cover and a second section inside the conduit. A third section is adapted for connection to a lead-out connector from the conduit and to the connector fixed to the plate at a distance from the reactor.

Abstract: A system for removing debris from a nuclear fuel assembly includes a work platform disposable on the fuel assembly racks in a spent fuel pol. A support stand is mounted on the work platform and has a sliding support plate movable between a support position engageable with the lower end of the fuel assembly, and a retracted position permitting lowering of the fuel assembly through an opening in the work platform into one of the racks. A tool manipulation assembly is disposable on the platform and includes a rotatable turret-type tool mount carrying four different cleaning tools, including a pick, a brush, a water lance and a water-actuated tweezers. The tool manipulating assembly includes drive means for effecting X-Y-Z movement of the tool mount for working on the fuel assembly. Each tool is resiliently mounted in a tool holder which yields if the tool engages the fuel assembly in a given direction with a predetermined force, generating an alarm signal to prevent damage to the tool assembly.

Abstract: A fluid-filled network of connected conduits and valves receives an acoustic signal in the form of waves of predetermined frequency, amplitude, and time sequence. At a second location, an acoustic receiver senses the form of the waves in frequency, amplitude, and time sequence arriving from the transmitter. The comparison between the acoustic signal introduced into the network and the signal received from the network represents whether the valve settings are satisfactory for using the network as a unit.

Abstract: A control rod testing apparatus with a testing subassembly (30) floatingly secured in a guide structure (20, 48, 50). Two centering means (64, 76) center the subassembly (30) around the rod being tested. Pancake coils (72) sense the proximity of sensing fingers (82) which side against the periphery of the rod being tested for the purpose of determining the geometry of the rod.

Abstract: A rod position indicating system for a pressurized water reactor generates within containment redundant sets of digital detector signals and applies both sets to each of two communications buses each controlled by a separate bus controller/serial output device located inside of containment. A pair of redundant serial data links transmits the redundant data from each bus controller/serial output device through containment to a dedicated CRT display and the plant computer each of which generates rod position displays from redundant information selected from one of the data links. The data for each rod is selected individually from the redundant signals received on the one data link. Rod position is presented in bargraph form on a multi-page display which includes overall status information along with the detailed presentations.

Abstract: A monitoring system for detecting changes in the liquid levels in various regions of a water-cooled nuclear power reactor, viz., in the downcomer, in the core, in the inlet and outlet plenums, at the head, and elsewhere; and also for detecting changes in the density of the liquid in these regions. A plurality of gamma radiation detectors are used, arranged vertically along the outside of the reactor vessel, and collimator means for each detector limits the gamma-radiation it receives as emitting from only isolated regions of the vessel. Excess neutrons produced by the fission reaction will be captured by the water coolant, by the steel reactor walls, or by the fuel or control structures in the vessel. Neutron capture by steel generates gamma radiation having an energy level of the order of 5-12 MeV, whereas neutron capture by water provides an energy level of approximately 2.2 MeV, and neutron capture by the fission fuel or its cladding provides an energy level of 1 MeV or less.

Abstract: For holding the reactor core in the confining reactor vessel, a support is disclosed that is structurally independent of the vessel, that is dimensionally accurate and stable, and that comprises tandem tension linkages that act redundantly of one another to maintain stabilized core support even in the unlikely event of the complete failure of one of the linkages. The core support has a mounting platform for the reactor core, and unitary structure including a flange overlying the top edge of the reactor vessels, and a skirt and box beams between the flange and platform for establishing one of the linkages. A plurality of tension rods connect between the deck closing the reactor vessel and the platform for establishing the redundant linkage. Loaded Belleville springs flexibly hold the tension rods at the deck and separable bayonet-type connections hold the tension rods at the platform.

Abstract: Apparatus for measuring the pitch between adjacent rods in a row of spaced-apart rods in a nuclear fuel assembly at selected points along the length of the rods, wherein the fuel assembly is relatively positioned angularly about its longitudinal center line with respect to a wand positionable to any selected point along the length of the rods carrying two spaced-apart, non-contact proximity sensors is transversely moved along the row of rods. An output signal of unique value is generated when the sensors are equally distant from a rod or adjacent rods. Means are provided for measuring the distance between the occurrence of the alternate unique signals as a measure of the pitch between adjacent rods.

Abstract: A digital rod position indicator having discrete coils spaced along the travel path of an elongated magnetically permeable member stores in digital form compensation signals for automatically adjusting the location relative to the coils at which the digital output signal representative of the position of the end of the elongate member transitions from one code to the next. The appropriate compensation signal is addressed using the digital output signal and a correction factor which takes into account the direction of movement including reversals.

Abstract: A repair device for removing an inner surface layer on a feed-water connector of a reactor pressure vessel received in a reactor housing having an assembly platform with a carriage displaceable thereon transversely to the reactor pressure vessel, the repair device includes centering means located at a lower end of a telescopically extensible upright tube suspended from the carriage for centering the lower end of the upright tube in the pressure vessel, the centering means having at least two outwardly swingable supports and a hydraulic system for swinging the two supports outwardly umbrella-like; a supporting frame for a feed rod also disposed at the lower end of the upright tube, the feed rod being horizontally self-supporting at an end thereof; a drive motor connected to the feed rod for rotating the feed-rod; means located at the self-supporting end of the feed rod for centrally fixing the self-supporting end in the feed-water connector of the reactor pressure vessel; and a horizontally displaceable turnin

Abstract: A method and means of non-invasively determining the liquid level and density in a nuclear power reactor pressure vessel is disclosed. In general the method consists of detecting neutron levels external of the pressure vessel at least at positions adjacent the bottom of the fuel core, the center of the fuel core and the top of the fuel core; and the detected neutron level signals are directed to monitoring means.The detecting means may comprise fission chambers and monitoring means may comprise simple electric meters.

Abstract: Coils placed at spaced locations along the path of an axially movable magnetically permeable and/or electrically conductive rod, which changes the impedance of each coil as it passes through, are connected in sets with each set comprising two series connected groups of equal numbers of parallel connected, non-adjacent coils energized by an a-c source. The voltage at the common node of each set of coils, which fluctuates as equal and unequal numbers of coils in the two groups in a given set are penetrated by the end of the rod, is compared with the voltage at the common node of a pair of series connected resistors, also energized by the a-c source, to generate one digit of an unambiguous, multi-digit, digital rod position signal. Since only one signal wire to the remote electronics is required for each set of coils, and since they only carry a voltage signal, the required wiring is minimized.

Abstract: A wide range flux monitoring assembly is provided for in-core neutron flux monitoring in a nuclear reactor vessel. The assembly comprises a fixed in-core power range monitor and a fixed in-core extended range start-up monitor which are connected to signal processing circuitry means for generating signals representative of neutron flux in the reactor vessel. The extended range start-up monitor includes a fission chamber including an anode, a cathode, a neutron sensitive material interposed between the anode and the cathode and a cable assembly for communicating electrical signals between the anode and the cathode to the signal processing circuitry means. An insulating oversheath is disposed about the extended range start-up monitor for insulating the fission chamber from reactor vessel potential. The oversheath comprises a casing having an inner wall and an outer wall and includes an insulating layer interposed between the fission chamber and the inner wall.

Abstract: Device for locating the position of a nuclear reactor control rod which is suspended from a shaft (12) sliding vertically inside an adaptor tube (10, 11) under the effect of a screw-nut mechanism which comprises a nut-forming rotor (14) mounted to rotate around the vertical axis of the tube (10) and provided with a threaded bore in which is engaged a corresponding threaded part (13) of the shaft (12).

Abstract: The invention provides an electromagnetic technique for repositioning garter springs, located between the coolant tubes and calandria tubes of fluid cooled nuclear reactors in which the garter springs are not directly accessible by mechanical means. An electromagnetic coil is advanced along the selected fuel channel to a position adjacent the garter spring, and a current pulse is passed through the coil thereby to exert an electromagnetic repulsive force on the garter spring having a component in the direction of the required displacement.