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: A guide tube inspection camera fixture for inspecting internal surfaces of nuclear reactor control rod guide tubes is provided. In an exemplary embodiment, the guide tube camera fixture includes a base plate, a unit-body tower having a first end and a second end, and a support bracket coupled to the unit-body tower. The unit-body tower is coupled to the base plate, and the support bracket is configured to support an inspection camera.

Abstract: The measurement device comprises a real-time measurement-signal acquisition module (25) and means (23, 24) for connecting the cables for picking up the voltage from electrical windings for measuring the movement of the control rods to the acquisition module (25), in order to deliver, to the acquisition module (25), voltage signals corresponding to the voltage induced in the windings while the control rods are being dropped. The signal acquisition module (25) is thus permanently connected to the voltage-signal pickup cables (29) and the signals relating to the set of nuclear reactor control rods may be recorded simultaneously. Means (26, 27) for using the voltage signals delivered by the acquisition system (25) allow the drop times of the control rods to be determined.

Abstract: With this method it is possible to evaluate opposing friction forces occurring after a certain operating time on a mobile object in a guide.

Abstract: A method for inspecting an irradiated fuel element in a nuclear power plant includes the step of measuring, with a measuring device, a spacer of a fuel element for providing measurements of the spacer. The measuring device also measures a calibration rod for providing measurements of the calibration rod, the calibration rod having known dimensions. The measurements of the spacer are calibrated by using the measurements of the calibration rod. It is possible thereby to measure at least the maximum width of the spacer with a measuring error of less than 20 &mgr;m. A device for inspecting an irradiated fuel element in a nuclear power plant is also provided.

Abstract: An inspection apparatus for inspecting welds in a nuclear reactor jet pump includes a probe subassembly rotatably and linearly movably coupled to a frame structure configured to attach to a top flange of the reactor pressure vessel. The probe subassembly includes a plurality of probe arms pivotably coupled to a housing, with each probe arm including a sensor. The probe arms are pivotably movable between a first position where the probe arms are parallel to a longitudinal axis of the probe subassembly, and a second position where the probe arms are at an angle to the longitudinal axis of the probe subassembly. An insertion subassembly couples to the jet pump suction inlet. The insertion subassembly is sized to receive the probe subassembly and guide the probe subassembly into the jet pump through the jet pump suction inlet.

Abstract: In order to control the perpendicularity of a component (10) such as a nuclear fuel pellet, this component is placed upon a support plane and measurements are taken, by means of two pairs of laser micrometers (A1, A2; B1, B2), of the distances separating diametrically opposed generators of the component from a rod of reference (T, T′), at two different levels and in two measuring planes (P, P′) perpendicular to each other. From this is derived a maximum out-of-true perpendicularity of the component being controlled.

Abstract: Compliance with administrative limits on cumulative exposure of control rod groups in the reactor core, is monitored by computing the incremental effective exposure for each group commensurate with core power, for each time increment at which each group is within the position range where an administrative limit is imposed. The increments of effective exposures for each group are accumulated, and the accumulated effective exposure for each group is compared with the administrative limit to each group. This comparison is then displayed to the reactor operator, preferably using either a “rolling wheel” or “sliding bar” format.

Abstract: A method for measuring the drop time of a rod in nuclear reactor with the rod position indication system coils remaining energized. The signal generated at the coils includes both the rod drop trace and the coil power. A filter is applied to separate the rod drop trace from the coil power. The drop time of all rods in a reactor can be measured simultaneously in a single test. Furthermore, the test data results are plotted automatically with plot overlay capability to compare rod drop traces to the results of previous tests or to compare an individual rod to another within the same test.

Abstract: A position verification apparatus comprising a movable member disposed within and movable with respect to a housing containing the movable member, a means for generating a magnetic field within the housing, a first magnetically responsive means for sensing the position of the movable member and outputting a signal indicative of the position of the movable member, a second magnetically responsive means for sensing the presence of the movable member and outputting a signal indicative of the position of the movable member and a means for comparing the signal output from the first magnetically responsive means and the signal output from the second magnetically responsive means.

Abstract: A reactor-internal equipment handling apparatus which is capable of reducing work required to load/unload control rods, fuel supports, and control rod guide tubes, includes a control rod holding unit (16) for releasably holding a control rod (7) which is loaded into a reactor vessel (1), and fuel support/control rod guide tube holding unit (17) for releasably holding a fuel support (8) which supports a bottom end of a fuel assembly (10) and a control rod guide tube (6) on which the fuel support (8) is placed. The control rod holding unit (16) and the fuel support/control rod guide tube holding unit (17) are fitted to a main body frame (26) which can be hoisted down inside the reactor vessel (1).

Abstract: Compliance with administrative limits on cumulative exposure of control rod groups in the reactor core, is monitored by computing the incremental effective exposure for each group commensurate with core power, for each time increment at which each group is within the position range where an administrative limit is imposed. The increments of effective exposures for each group are accumulated, and the accumulated effective exposure for each group is compared with the administrative limit to each group. This comparison is then displayed to the reactor operator, preferably using either a “rolling wheel” or “sliding bar” format.

Abstract: An improved heated junction thermocouple cable arrangement for use with a nuclear reactor heated junction thermocouple having sensors with an unheated thermocouple, a heated thermocouple, and a heater coil, shares power conductors between multiple heater coils. The thermocouple conductors are separated from the power conductors to eliminate the possibility of interference with the thermocouple conductor signals. The heater coils are ganged in parallel and if one heater coil fails, power is still supplied to the remaining heater coils connected to a pair of power conductors.

Abstract: A magnetostrictive wire control rod position detector assembly which will allow nuclear reactor output to be increased, control performance to be improved, and peripheral equipment to be rationalized by continuously and accurately detecting the position of a control rod in a reactor core is provided. A magnetostrictive wire control rod position detector assembly (20) comprises: a magnet or magnets (21) mounted on a non-magnetic portion of a movable member (3) which is free to move in the longitudinal direction on the inside of a cylindrical member (1) and is partly composed of a non-magnetic material; a magnetostrictive wire detector (22) longitudinally mounted on the outer circumference of said cylindrical member, which is provided with a receiver (26); and a pulsed current generator circuit (37) which supplies a pulsed current from the receiver end to the magnetostrictive wire of the magnetostrictive wire detector.

Abstract: Methods and apparatus for examining a nuclear reactor shroud are described. In one embodiment the inspection apparatus includes a drive system, a mast subassembly, and a scanner subassembly. The drive system includes at least two drive assemblies that engage the shroud top to move the inspection apparatus relative to the shroud. The mast subassembly is coupled to the drive system and includes a roller foot which engages the shroud bottom flange to prevent movement of the inspection apparatus during scanning of the shroud. The scanner subassembly is movably coupled to the mast subassembly and includes a horizontal frame, a scanner carriage having a turntable, a movable plate and a scanner. The scanner subassembly coupled to the mast subassembly provides the scanner with four degrees of motion.

Abstract: The spacer envelope measurement system includes a generally U-shaped fixture having support plates extensible into positions overlying the spacer for supporting the fixture from the spacer. Extensible heads are carried by the fixture for engaging the spacer, followed by the heads of measurement gauges whereby, upon extending the heads into clamping engagement with the spacer along opposite sides thereof, the measurement gauges accurately determine the lateral dimensions of the irradiated spacer. A spacer bar clamp member is pivotal between positions opening the fixture opposite the base leg of the U-shaped fixture, enabling the bundle to reside within the U-shaped opening and a second position closing the opening for aligning the fixture and the bundle. The measurements are taken under water in a nuclear fuel service pool.

Abstract: A method for detecting the dropping of at least one control element in a reactor core of a power station by delaying signals output by detectors disposed along a fall path of the control element in such a way that they are approximately simultaneous. This improves a registration of the dropping of the control element by improving a ratio between a useful signal and a noise signal.

Abstract: The length gauge includes an elongated standards rod, an indicator location block carrying a gauge and an indicator set block. The set block is applied to the location block and the gauge is zeroed out at a known distance between the movable element on the gauge and a reference surface. Water rods are assembled to a tie plate and the gauge is used to measure the length of the adjustable length water rods. The location block receives in a recess a portion of the tie bar of the water rod. The standards rod engages the tie plate and the gauge pin engages the opposite end of the standards rod. Any deviation in the length of the water rod from a designed length is indicated on the gauge.

Abstract: A CEDM data acquisition system (40) receives analog coil-current signals from control element drive mechanism coils (18, 20); conditions the analog signals to remove noise induced therein by the electronic circuitry (44) associated with the control element drive mechanisms; digitizes the conditioned analog signals; displays the acquired test data; and records the data for future use. The inventive data acquisition system preferably has the ability to simultaneously measure, display and record coil-current data for all of the five coils associated with each CEDM rod-group with respect to time. Further, the inventive data acquisition system preferably allows the user to monitor, display and record data for up to eight CEDMs simultaneously. It also allows the measurement of rod-drop times during rod-drop testing of the CEDMs.

Abstract: A method and an apparatus detect the dropping of at least one control element in a reactor core of a power station by delaying signals output by detectors disposed along a fall path of the control element in such a way that they are approximately simultaneous. This improves a registration of the dropping of the control element by improving a ratio between a useful signal and a noise signal.

Abstract: Apparatus for rectifying the tendency of a fuel assembly (1) to incline from the perpendicular has a top nozzle support (19) and a base assembly (18) for supporting, respectively, a top nozzle (7) and a bottom nozzle (2) of the fuel assembly. Incorporated in the base assembly is an elevating device (78, 79) which is operable to raise the fuel assembly. When raised, a grinding assembly (62) in the base assembly is able to remove material from the lower surfaces of the bottom nozzle so that they lie in a horizontal plane. The elevating device comprises a gimbal mounting arrangement which includes a gimbal (94) movably supported on a gimbal mount (88) by means of cooperating male and female spherically-shaped bearing surfaces. The grinding assembly includes a grinding wheel (66) which is mounted on a rotor (43) arranged for rotation about an axis along which the elevating device raises the fuel assembly so that material can be removed from each of the lower surfaces during one revolution of the rotor.

Abstract: Changes in the value of the control element assembly position signal (26,28) are monitored over a preselected time period, and a determination is made whether these changes conform to a regular, predetermined pattern (S.sub.1), characteristic of normal control element assembly motion. If any change deviates (S.sub.2,S.sub.3) from the pattern by more than a permissible tolerance, a position invalidity signal is generated.

Abstract: A measurement chamber (18) having an upper and a lower region is at substantially the same elevation as a horizontal pipe (12) having a top region and a bottom region. An equalization line (14) fluidly connects the top region of the pipe (12) to the upper region of measurement chamber (18). A sample line (16) fluidly connects the bottom region of pipe (12) to the lower region of the measurement chamber (18). Heat junction thermocouples (22) generate a signal indicative of the level of fluid in the measurement chamber (12) which is equal to the level of fluid in the pipe (12). The signal is transmitted to a remote location by line (24).

Abstract: The apparatus is for internal inspection of a guide tube of a nuclear fuel assembly and measurement of deformations of a zone of smaller diameter in a terminal portion of the tube. The apparatus has a stick whose distal portion presents, in succession, starting from a distal end of the stick-shaped means, a guiding swelling having an easy fit in the zone of smaller diameter and two projections. The first projection carries two sets of diametrically opposite strain sensors provided with conductors linking them to a proximal end of the stick. A sleeve slides in a running portion of the guide tube above the zone of smaller diameter and slides over the stick. The sleeve and said stick-shaped means have mutually cooperating abutments for limiting displacement of the sleeve towards the distal portion to a position where the sleeve surrounds the stick.

Abstract: A refueling machine having relative positioning capability for refueling a nuclear reactor. The refueling machine includes a pair of articulated arms mounted on a refueling bridge. Each arm supports a respective telescoping mast. Each telescoping mast is designed to flex laterally in response to application of a lateral thrust on the end of the mast. A pendant mounted on the end of the mast carries an air-actuated grapple, television cameras, ultrasonic transducers and waterjet thrusters. The ultrasonic transducers are used to detect the gross position of the grapple relative to the bail of a nuclear fuel assembly in the fuel core. The television cameras acquire an image of the bail which is compared to a pre-stored image in computer memory. The pendant can be rotated until the television image and the pre-stored image match within a predetermined tolerance.

Abstract: An improved system and method for testing the free fall time of nuclear reactor control rods. The system employs a plurality of sensor coils which are arranged in tandem along the control rod drive rod housing, having a plurality of the sensors energized by a single transformer. During the rod drop test, the transformers' primary windings are shorted.

Abstract: A system for seating at least one gasket member used to seal a pressure vessel penetration where a column penetrates therethrough includes a tubular member, a column which penetrates through the tubular member in a telescoping manner and is normally movable axially relative to and in axial sliding communication with the tubular member before assembly of hardware used to seat the gasket member, and at least one gasket member for sealing the interfaces between the tubular member and the column. The system also includes spacer for filling the axial gap in series with at least one properly seated gasket member between the column and the tubular member and at least one properly seated gasket member when the column cannot be suitably positioned axially relative to the tubular member in order to properly seat at least one gasket member during assembly of hardware utilized to seat at least one gasket member.

Abstract: In a boiling water reactor having a core shroud disposed within a reactor vessel and a plurality of tie rods installed between vertically spaced sites on the core shroud as part of a core shroud repair, a method of measuring tie rod preload after installation includes the steps of lowering a tool into the reactor vessel from a remote location positioned externally of the reactor vessel, attaching the tool to an upper portion of a tie rod, using the tool to apply a tensile load along a longitudinal axis of the tie rod, measuring the tensile load applied to the tie rod, measuring axial displacement of the tie rod in response to the applied tensile load, plotting the applied load versus the axial displacement measured, and identifying a change in slope on the load-displacement plot occurring at a load corresponding to the tie rod preload.

Abstract: This invention provides a device for capacitively measuring the distance to an object, which comprises an electrode that will couple capacitively with the object, a shield that surrounds the electrode and is electrically isolated from the electrode by means of insulation, and a layer of insulation that surrounds the shield, wherein the insulation between the electrode and the shield, and the insulation that surrounds the shield, are formed by deposition.This invention further provides a method for measuring the distance to a solid object, which comprises forming an electrode that will capacitively couple with the object, depositing a layer of insulation over at least part of the electrode so that the insulation surrounds the electrode, depositing a layer of metal over the insulation to form a shield, and depositing a second layer of insulation over the shield.

Abstract: An eddy-current probe (10) is moved in the axial direction of the clad of the rod (1), a first position of the probe (10) is determined in the axial direction, for which a signal from the probe is representative of the presence of the internal surface of the bottom end plug of the rod (1) and at least one second position for which the signal from the probe is representative of the presence of the end part of the spring of the fuel rod (1) or of the internal surface of the top end plug of the fuel rod (1). The total length and/or the length of the fissile stack are calculated from the first position and from the second position of the probe (10). The measurements may be performed inside the spent fuel storage pond of a reactor.

Abstract: A condensation vessel for the measurement of steam pressure includes a steam zone, a steam line which opens in the steam zone at an entrance, a condensate zone which is directly adjacent the steam zone and geodetically below the entrance, and a discharge device which is connected to the steam zone and which serves for a discharge of steam and noncondensable gases from the condensation vessel. A method for operating the condensation vessel includes condensing steam which contains an increased fraction of a noncondensable gas, in particular radiolysis gas, out of the steam zone. The gas is led out of the condensation vessel in dissolved form through the discharge device, with the result that the risk of faulty measurement is largely ruled out, since virtually no gas is dissolved in the condensate within the condensate zone. The condensation vessel can be installed in a simple way, even in the course of retrofitting, for measuring the filling level of a reactor pressure vessel.

Abstract: In a method of and an apparatus for checking the degradation of the pressure vessel of a nuclear reactor with the pressure vessel of the nuclear reactor being directly measured in a non-destructive manner, a magnetic yoke having an exciting coil and a magnetic flux measuring coil is closely placed in contact with the inner wall of the pressure vessel of the nuclear reactor. The hysteresis magnetization characteristics of the closed magnetic path formed by the magnetic yoke and the pressure vessel of the nuclear reactor are measured. The coercive forces are obtained by the hysteresis characteristics. The hardness of the material comprising the pressure vessel of the nuclear reactor at the part of the magnetic path formed in the pressure vessel of the nuclear reactor is obtained from the coercive forces and the degradation of the material comprising the pressure vessel is checked from the hardness.

Abstract: An apparatus for measuring fuel assembly bow and twist comprising a fixturing apparatus, a reference device and an ultrasonic measuring device.

Abstract: A device for the measurement by induction of a medium through a metal wall using a transmission portion permitting the induction of a signal in the medium beyond the metal wall and a receiver for receiving a signal transmitted by the medium in response to the induced signal. The transmission portion includes at least one current generator directly connected to the metal wall in such a way that the current passing into the wall induces a signal beyond the wall.

Abstract: An automatic refueling apparatus has a travel carriage, a traverse carriage and a fuel assembly grappling apparatus composed of a grapple, an extension pipe and a hoist. The automatic refueling apparatus also includes a system for controlling automatic fuel transferring operations, in which a calculation unit and a control unit are provided. After the positions of a start point and a target terminal point of a fuel assembly transfer are input through an input device, the calculation unit determines the shortest route from the start point to the terminal point in a preset fuel transferring permitted region, and the control unit generates driving command signals for moving the fuel assembly grappling apparatus along the obtained shortest route through a simultaneous control along X, Y, Z (Z: an elevation direction vertical to a X-Y horizontal plane of the grapple) and .theta. (a rotation direction in a X-Y horizontal plane of the grapple) axes.

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.

Abstract: An automated system for determining positions of a plurality of nuclear fuel assemblies organized in an array within a housing of a nuclear power plant includes a radiation hardened, underwater camera for inputting images of the nuclear fuel assemblies with respect to each other or with respect to a baffle wall of a nuclear reactor core, a digital signal processor for generating a second digitized image including a plurality of pixel elements of the nuclear fuel assemblies from the first image, and a workstation for determining the positions of the nuclear fuel assemblies with respect to the baffle wall from counts of the pixel elements.

Abstract: A method and an apparatus for inspecting a core shroud by remote operation. The apparatus is a robotic scanning device which can be installed in the narrow space between the core shroud and the jet pumps and which can scan azimuthally and vertically around the circumference of the core shroud. The scanning device provides gross positioning to the area of interest and precise motion control in a limited scanning range. The scanning uses a thin wide arm to support a bank of transducers at its bottom end, and is rigidly mounted to a precision two-axis positioner at its top end. The arm is of narrow thickness to pass through the 0.5-inch access opening and to allow radial flexibility to absorb surface contour variation over the inspection area. The transducer mounting includes a water jet thruster to provide a radially inwardly directed reaction force to maintain the transducers in contact against the shroud. The arm is fabricated with a row of longitudinal holes extending throughout its length.

Abstract: In a drive device of control rod drive mechanisms, a large number of control rod drive mechanisms are divided into a plurality of groups, and there are provided, for each group, a control rod changeover device, and an inverter power source and inverter controller constituting the drive power source. The drive device comprises a control unit that receives control rod position signals from each of the control rod drive mechanisms and that outputs control signals to the control rod changeover device and inverter controller, and a man-machine device constituting an interface with the operator, that outputs control rod drive information to this control unit.

Abstract: The tubular cladding (1) comprises an internal surface of substantially prismatic shape, having successive faces. An ultrasonic examination head (3) makes it possible to emit ultrasound waves in the form of pulses from the outside of the cladding (1), so that the ultrasound waves pass through the wall of the cladding (1) and scan the wall over its entire periphery. The frequency of the ultrasound pulses is adjusted as a function of the circumferential scanning speed of the cladding (1). An ultrasound signal reflected by the internal surface of the cladding (1) is recorded and the reflected signal is analyzed in order to examine the number and the amplitude of the faces and the variation in thickness of the tubular cladding (1) over one revolution.

Abstract: A method for compensating a rod position indication system for non-linearity comprises the steps of applying an excitation current to a primary of a sensor for inducing a generally linear voltage that is representative of the position of a control rod on a secondary of the sensor. The excitation current includes a first frequency which is sufficient to provide the generally linear output for the sensor. The excitation current is then modified to include a second frequency which is sufficient for providing the generally linear output when the first frequency is insufficient to provide the generally linear output.

Abstract: A differential pressure detection equipment typically represented by a water level measuring apparatus provided for a nuclear power plant includes a condenser having a steam flow-in port connected to a steam phase side pressure detector through a connection pipe, a reference water column side instrument pipe connected to a bottom portion of the condenser, a variable water column side instrument pipe connected to a liquid phase side pressure detector and a pressure difference detector connected to both the instrument pipes for detecting a pressure difference between a reference water head pressure of the reference water column side instrument pipe and a variable water head pressure of the variable water column side instrument pipe. The connection pipe has an upward inclination .theta. from the steam phase side pressure detector to the condenser so as to satisfy an equation of 0<tan .theta.<D/L, in which D is an inner diameter of the connection pipe and L is an axial length of the connection pipe.

Abstract: A tool which can be remotely operated to precisely measure the downcomer annulus width at the elevation of the top guide support ring. The measuring tool has a support frame adapted to be grappled and then hooked onto the upper rim of the shroud, and a measuring subassembly mounted on the support frame. The measuring subassembly has a contact block mounted on a bearing-mounted slider. The slider is translatable between a retracted (i.e., "home") position and an extended position in response to actuation of a cylinder mounted on the support frame. When the tool is properly installed on the rim of the shroud, the slider travels radially outward in response to actuation of the cylinder until the contact block abuts the opposing inner surface of the reactor pressure vessel wall, i.e., the slider is stopped.

Abstract: A method and system for indicating the position of a nuclear reactor control rod which is suspended from a shaft sliding vertically inside a travel housing. Primary and secondary coils are wound around the travel housing and an AC current travelling through the primary coil induces a secondary voltage across the secondary coil and a primary voltage across a secondary coil of an isolation transformer. The primary and secondary AC voltages are low pass filtered, rectified into DC voltages, and low pass filtered a second time. The secondary DC voltage is divided by the primary DC voltage and a ratiometric signal is produced. The ratiometric signal is compensated by decoupled zero and span adjustments and by a temperature compensation adjustment. A linear correction offset is calculated from data stored in an EPROM and summed with the ratiometric signal yielding a module output signal which is a linear representation of the control rod position.

Abstract: A tank (18) forms a chamber having an upper and lower region. The tank (18) is in even elevation with a horizontal pipe (12) having a top region and a bottom region. An upper connecting pipe (14) fluidly connects the top region of the pipe (12) to the upper region of tank (18). A lower connecting pipe (16) fluidly connects the bottom region of pipe (12) to the lower region of the tank (18). Heat junction thermocouples (22) generate a signal indicative of water in the pipe (12). The signal is transmitted to a remote location by line (24).

Abstract: A system for determining the level of coolant in a depressurized nuclear reactor comprises a first set of pressure transducers located in the coolant piping and a second set of pressure tranducers located at the top or near the top of the pressurizer. Electrical signals from these independent transducers are fed by cable to a controller with a microprocessor in the reactor control room where the coolant level is calculated and displayed. Compensations for signal error, coolant temperature and coolant chemistry are provided.

Abstract: An alignment device is used with a spent fuel shipping container including a plurality of fuel pockets for spent fuel arranged in an annular array and having a rotatable cover including an access opening therein. The alignment device includes a lightweight plate which is installed over the access opening of the cover. A laser device is mounted on the plate so as to emit a laser beam through a laser admittance window in the cover into the container in the direction of a pre-established target associated with a particular fuel pocket. An indexing arrangement on the container provides an indication of the angular position of the rotatable cover when the laser beam produced by the laser is brought into alignment with the target of the associated fuel pocket.

Abstract: An uncoupling tool has a two-module design: one module being a driver assembly for developing the uncoupling movement and the other module being a probe assembly for verifying the uncoupled condition. The probe assembly attaches to the threaded end of the piston tube with its probe extending inside the piston tube. The driver assembly attaches to the CRD ring flange. The probe assembly detects the ring magnet in the drive piston using analog position sensors which operate on the principle of the Hall effect and solid state circuitry. A top sensor provides a signal indicating that the control rod is in its "full out" position; a bottom sensor provides a signal indicating that the control rod is uncoupled; and an intermediate sensor provides a signal indicating that the control rod is in a transition position between the "full out" and uncoupled positions. The probe incorporates spacers which focus the magnetic flux onto the sensors.

Abstract: A system for inspection and mending in a reactor vessel of a nuclear reactor comprises a track mechanism, support mechanisms for supporting the track mechanism, an inspection apparatus traveling on the track mechanism, at least one mending apparatus traveling on the track mechanism, a setting mechanism for lowering all the above-described mechanisms and apparatus in the reactor vessel, each of which is composed so as to pass through a hole of an upper grid of a reactor, and an installing mechanism for positioning the support mechanisms fixed with two of the upper grid, a core support plate and internal structures below the core support plate and the track mechanism at the inside of the reactor vessel by remote control and for attaching the inspection apparatus and the mending apparatus to the same track mechanism by remote control.

Abstract: A system for mapping absolute acoustic noise intensity in a three-dimensional acoustic noise field, and using three-dimensional absolute noise intensities to infer operational or performance characteristics of components or structures within the monitored field. Localized noise sources are extracted using a distant array of transducers, and the absolute intensity can be measured even when totally masked by background noise at the transducer locations. The system includes an integrated sensor installation; a neural network detection system algorithm; a zoom system to precisely examine a small region in the steam generator vessel; a fuzzy logic system detection algorithm; and an expert detection system. The signal processing subsystem operates at three different levels of detection. At the top level of detection a trained neural network system monitors the vessel length for any indication of a leak. The proposed approach uses discriminators which do not require any beamforming of the sensor signals.