Abstract: A maintenance of a suppression pool or spent fuel storage pool in a reactor primary containment vessel of a nuclear power plant includes a cleaning step of a water in the suppression pool and a decontamination step of an interior of the suppression pool, and in the maintenance, the coated film applied on an inner surface of a wall portion of the suppression pool is inspected. These cleaning, decontaminating and inspecting steps are performed by divers while maintaining a water level in the suppression pool.

Abstract: An apparatus for ultrasonically examining a weld in a nuclear steam supply system includes an elongated guide rod for positioning within a pipe of the nuclear steam supply system. An ultrasonic transducer is positioned at an end of the elongated guide rod. A collapsible shoe encloses the ultrasonic transducer. The collapsible shoe includes a biasing mechanism to allow the collapsible shoe to pass through the pipe while the pipe is at a first circumference and while the pipe is at a second circumference. The collapsible shoe continuously contacts the pipe to establish ultrasonic coupling for the ultrasonic transducer.

Abstract: A flexi-rail assembly for supporting and positioning tools for inspecting a nuclear power plant steam generator. The flexi-rail assembly includes a housing; at least one lock assembly carried by the housing for coupling the housing to a support structure; and a carriage assembly movably supported by the housing for supporting and positioning inspection tools such as a robot manipulator arm and leg assembly. The housing includes a hollow rear portion for receiving at least one cylinder supporting a movable surface, wherein the cylinder is coupled to a source of pressurized fluid. The housing also supports at least one recessed surface for receiving the lock assembly. The lock assembly includes the cylinder and at least one tubular member. The tubular member includes an open center and at least two openings formed in the surface of the tubular structure.

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: An EMAT testing device for nondestructively testing tubes for surface defects and displaying the results has a EMAT transmitter arranged collinear with a pair of EMAT receivers. The EMAT receivers each receive a pair of oppositely propagating circumferential acoustic surface waves from the transmitter at different times and the relative amplitudes of the received waves are compared to located defects adjacent the receivers in the tube.

Abstract: A device for inspecting the interior of steam generators capable of visually inspecting interior of tubes in steam generators, including upper portions steam generator tubes, tops and bottoms of support plates, wrapper-to-support plate welds, and other internal structures.

Abstract: A method and an apparatus introduce a self-propelled in-pipe manipulator into the interior of a pipeline. A hollow body receives the in-pipe manipulator, is open at least at one end surface and is positioned at an opening of the pipeline, from where the in-pipe manipulator can drive on its own into the pipeline.

Abstract: A sinusoidal voltage is appied to a zirconium alloy clad fuel rod. The current is measured and the impedance is determined to provide a check for the compactness and adhesion of an oxide surface layer on the fuel rod.

Abstract: An underwater inspection/repair apparatus comprises a sealing device provided around an opening portion of a watertight vessel, a pushing mechanism provided to the watertight vessel, a water discharge pump provided to the watertight vessel for discharging water in an inside of the watertight vessel, and a compressed air supplying device for supplying a compressed air into the inside of the watertight vessel. A top end of the sealing device is pushed against an inner wall surface of the reactor vessel by a reaction force generated when the pushing member of the pushing mechanism is pushed against the reactor internal structure, so that the inside of the watertight vessel can be isolated in a watertight manner. The pneumatic water discharge pump includes a pneumatic pressure cylinder driven by a pneumatic pressure, and a water discharge cylinder cooperated with the pneumatic pressure cylinder.

Abstract: A preventive maintenance apparatus for structural members inside a nuclear reactor pressure vessel includes a ring-shaped guide rail having a plurality of lugs which is placed on an upper flange of a core shroud provided inside a reactor pressure vessel. At least some of lugs separately engage with a plurality of guide rods provided on an inner surface of the reactor pressure vessel. A turntable is rotated on the guide rail. A first discharging nozzle moving apparatus placed on the turntable moves a first discharging nozzle for adding compressive remaining stress to an outer surface of the core shroud in a radial direction of the core shroud and in an axial direction of the core shroud. A second discharging nozzle moving apparatus placed on the turntable moves a second discharging nozzle for adding compressive remaining stress to an inner surface of the core shroud in a radial direction of the core shroud and in an axial direction of the core shroud.

Abstract: Automated inspection assemblies for scanning pipes of a nuclear reactor are described. In one embodiment, the assembly includes a mounting subassembly and a scanning subassembly. The mounting subassembly includes a clamp configured to be mounted to selected pipes in a nuclear reactor pressure vessel, and the scanning subassembly is movably coupled to the mounting subassembly. The scanning assembly includes a scanning head configured to scan at least a portion of the circumference of the pipe to be inspected, and the scanning head includes a substantially "U" shaped transducer support assembly sized to receive the pipe. Transducer elements are coupled to the transducer support assembly legs, and the transducer support assembly is configured to rotate about the pipe to inspect the pipe.

Abstract: Methods and apparatus for examining a nuclear reactor shroud are described. In one embodiment the inspection apparatus includes an elongate tubular upper section, an elongate middle section, an elongate lower section, and a scanner arm assembly movably coupled to the middle section. The inspection apparatus is configured to be inserted into the reactor pressure vessel through one of the openings in the reactor core plate. The upper section includes a bail handle and an indexing ring having an alignment lug, a plurality of slots and a movable locking tab configured to engage the slots. The lower section includes a rotary bearing located at the bottom end. The lower section is configured to engage and rest on a control rod drive housing. The middle section includes a movable door and a movable traveler plate movably coupled to the scanner arm assembly. The scanner arm assembly includes a fixed track, a movable track, a scanner carriage, and a scanner array.

Abstract: A nuclear fuel identification system for use in nuclear power plants has an imaging system having a video camera and an array of illuminators surrounding the video camera and positioned to shine onto a nuclear fuel cell. The illuminators are sequentially activated to provide a series of images each having a different shadow pattern. These images are then digitized and stored until a complete set of the images are available. At that time, the images are superimposed and optimized for improved contrast. By viewing the distinct shadow patterns on the nuclear fuel cell, the identifying markings are readily visible. In addition to the shadow imaging system, a variety of laser devices are used to accomplish similar image generating functions. Such laser devices include a laser scanner, a distance laser device, an interferometer, a holographic interferometer, and a bi-refringent crystal prism.

Abstract: An electrochemical corrosion potential sensor is fabricated by initially joining an electrical conductor to a sensor tip. An electrical cable is joined to the tip conductor. Ceramic powder is fused under heat around the tip conductor to form an integral annular electrically insulating band therearound to insulate the tip from the cable. The band may be formed by plasma spraying, or it may be molded and sintered to seal it to the tip and conductor without brazing. In a preferred embodiment, the band is formed of yttria-stabilized-zirconia or magnesia-stabilized-zirconia.

Abstract: Methods and apparatus for enabling repeatable positioning of inspection and other service tools on an inner diameter of a shroud wall between a top guide and core plate in a boiling water nuclear reactor are described. In one embodiment, the delivery system includes a positioning unit configured to attach to a shroud head flange, a strong back assembly, and a rail assembly connected to the strong back assembly. The positioning unit includes a horizontal member having a plurality of slots and circular shaped openings to mate with seismic pins on the shroud head flange, a radial member and a z-axis adjustment assembly. The radial member extends from the horizontal member to the z-axis adjustment assembly. The z-axis adjustment assembly includes a mast coupling and an elongate screw threadedly attached to the coupling so that as the screw rotates, the coupling moves relative to the radial member. The strong back assembly includes a mast and an extension unit.

Abstract: A coolant pipe blocking device for use in a nuclear power plant is provided to temporarily choke up a coolant inlet pipe to thereby inhibit fluid communication between a reactor and a steam generator, the steam generator having a coolant chamber in communication with the reactor via the coolant inlet pipe and a manway providing access to the coolant chamber. The pipe blocking device includes a plurality of hub segments(42-48) arranged along a longitudinal axis substantially with a uniform spacing to one another and an elongated, flexible, support rod(50) extending in a coaxial relationship with the longitudinal axis for interconnecting and keeping spaced apart the hub segments. A plurality of bladders(52-60) are arranged in an end-to-end relationship with respect to one another and attached to the hub segments to define a series of hermetically sealed air chambers.

Abstract: An actuator for performing work in a nuclear reactor is described. In one embodiment, the actuator includes an x-axis linear slide assembly, a y-axis linear slide assembly, and a z-axis linear slide assembly. The x-axis linear slide assembly is mounted to a junction box, the y-axis linear slide assembly is mounted on a carriage of the x-axis assembly, and the z-axis linear slide assembly is mounted on a carriage of the y-axis assembly. The actuator also includes motor assemblies coupled to respective linear slide assemblies. Each motor assembly includes a motor and a resolver sealed in a leakproof can. Pulley-timing belt assemblies couple each motor to a respective lead screw. Specifically, a drive pulley is connected to a rotor shaft of each motor, and a lead screw pulley is secured to an end of each lead screw. Each pulley-timing belt assembly also includes an idler pulley, and a belt extends around the lead screw pulley, the idler pulley, and the drive pulley.

Abstract: An electrochemical corrosion potential sensor includes a sensor tip electrically joined to a conductor, and a ceramic insulator joined to the tip around the conductor. A sleeve is joined to the insulator around the conductor, and is electrically insulated from the tip by the ceramic insulator. The insulator has an exposed surface axially separating the tip and sleeve, and a ceramic coating is bonded thereto for preventing dissolution of the insulator by reactor water. In a preferred embodiment, the ceramic insulator is sapphire, and the ceramic coating is yttria-stabilized-zirconia or magnesia-stabilized-zirconia which may be plasma sprayed over the insulator.

Abstract: An apparatus and a method for inspecting an outer jacket of a core containment in the vicinity of a heat shield surrounding the core containment, include an annular rail to be fixed to the core containment. A carriage is disposed on the annular rail for circumferential movement. A mast is supported on the carriage for axial displacement. A vertical carriage is movable along the mast in the direction of the longitudinal axis of the mast. An outrigger is disposed on the vertical carriage. An inspection device is carried by the free end of the outrigger for movement into a region between the outer jacket and the heat shield.

Abstract: An apparatus and a method for inspecting an outer jacket of a core containment in the region of a heat shield surrounding the core containment, include a plate mounted rotatably on a bottom of a storage basin. The core containment is deposited on the bottom. A mast is deposited on the bottom next to the core containment. A vertical carriage is disposed on the mast for movement in the longitudinal direction of the mast. An outrigger which is disposed on the vertical carriage can be introduced into a region between the outer jacket of the core containment and a heat shield and has a free end which carries an inspection device.

Abstract: At a reactor bottom, varieties of work are performed by a working apparatus, the work includes inspecting, cleaning and recovering radioactive corrosion products and other foreign matters deposited or stuck onto a foot mirror of a reactor pressure vessel in a light-water cooling reactor, and cutting, grinding and welding structural members in relation to the foreign matters. The working apparatus includes a body case having a shape of a vertically long tube, having an opening formed in a peripheral surface thereof. The body case being suspended from above the reactor pressure vessel to be installed over an upper end of a control rod driving mechanism housing which is vacant after withdrawal of a control rod driving mechanism from the housing.

Abstract: The apparatus for inspecting the rods of a cluster insertable in the core of a nuclear reactor comprises a body provided with sliding guide means for rods in m different orientations of the cluster, m being a submultiple of the number n of rods in the cluster, and a measurement jig carrying n/m heads (16) for eddy current examination and n/m probes (18) for ultrasound scanning placed on different guide paths. Each ultrasound probe (18) is constituted by an annular support surrounding a rod path and carrying a ring of individual transducers. The transducers are connected to a circuit for sequentially exciting the transducers in successive groups, causing the tube to be scanned circumferentially, and for electronic focusing towards the surface of a tube travelling on the path.

Abstract: An apparatus for inspection of a reactor pressure vessel uses a laser driven type underwater wall climbing robot guided by a laser pointer. The inspection apparatus uses a small and light underwater wall climbing robot for the quick and adequate inspection of weld lines of a reactor pressure vessel. Position control methods are provided for the stable guidance of the robot to desired three dimensional inspection positions on the reactor pressure vessel.

Abstract: A measurement system for measuring material deterioration in accordance with a magnetic field of the material in the presence of radiation. The measurement system includes a detection circuit which detects a magnetic field of the material and generates a signal indicative thereof which signal includes noise due to the radiation, a signal processing circuit including semiconductor devices to process the signal generated from the detection circuit and a noise reducing circuit for at least reducing noise in the generated signal which is due to the radiation. The signal processing circuit is installed at a place where a dose equivalent of radiation is equal to or smaller than that of a place where the detection circuit is installed.

Abstract: Methods and apparatus for performing repairs and inspections in a reactor pressure vessel (RPV) of a nuclear reactor are described. In one embodiment of the apparatus, a support mast facilitates the positioning of tools within the RPV, especially at locations that are extremely difficult to access using known methods and apparatus. In the one embodiment, a mast extends in the reactor pressure vessel and through an opening in the top guide and through an opening in the core plate. The mast includes an outer tube and an inner tube positioned at least partially within the outer tube. The inner tube is connected to a robotic arm. A slot is formed in the outer tube and the slot extends at least partially along the axial length of the mast. The portion of the inner tube positioned at the location of the slot is in free communication with the reactor components when the mast is positioned within the RPV. The robotic arm can access the reactor components through the slot in the outer tube.

Abstract: An inspection apparatus is suspended from a robotic positioning arm and is operable to inspect the surface of a boiling water reactor core shroud. The apparatus includes an attachment bracket connected to the robotic positioning arm. A guide is connected to the attachment bracket and receives an arcuate rail having a first end portion and an opposite second end portion. A motor assembly drives the rail within the guide to position the rail at a desired location along the core shroud surface relating to the guide. The rail carries a transducer assembly which is moved along the rail by a chain and sprocket assembly. As the motor assembly drives the rail, the chain and sprocket assembly simultaneously moves the transducer assembly along the rail to inspect the core shroud surface.

Abstract: Prompt Gamma Neuteon Activation Analysis (PGNAA) is employed to determined in situ the content of nickel, copper, or other embrittlement-enhancing elements within the weld metal joints of nuclear reactor pressure vessels.

Abstract: A probe inspects steam generator tubing for defects. The probe includes a transducer which generates a localized ultrasonic Lamb wave. The ultrasonic wave is transferred to the tubing by a coupling medium, such as water, that physically couples the transducer and the tubing. Defects in the tubing reflect the ultrasonic wave to the probe which detects the reflections. The results are then used to determine the length and depth of such defects as cracks, pitting, and thinning. The localized ultrasonic wave performs an inspection sensitive enough to detect ligaments between crack segments. This allows highly accurate predictions of tubing integrity and rupture strength.

Abstract: A system for ensuring the distribution of noble metal in the reactor circuit during plant application without measuring the reactor water for noble metal content by chemical analysis. The system performs the measurement of electrochemical corrosion potential in an autoclave or a high-flow test section that is connected to the reactor water circuit through sample lines downstream of the injection port, preferably the point in the reactor circuit which is furthest from the injection port. If the noble metal flows into the autoclave or test section at these distant points in the reactor circuit, then the noble metal will deposit on the test specimens inside the autoclave or test section.

Abstract: The detection device includes at least one thermocouple (10) arranged aligned with the bottom head of the vessel of the nuclear reactor, having a first branch (9) made of a first metallic material and at least one second branch (11) made of a second metallic material, different from the first material, welded to a point on the first branch constituting a hot junction of the thermocouple (10). The first branch (9) of the thermocouple has the form of an elongate hollow section. The device furthermore includes means for analyzing the measurements taken by the thermocouples (10).

Abstract: An integrated apparatus for inspecting the arms of jet pump beams using eddy current technology, while also scanning the borehole region using ultrasound technology. In order to inspect the jet pump beam arms, a special scanner is required to properly move an eddy current coil in two dimensions over the complex machined surface on top of the arms. The scanner has two axes of motion and can perform a raster scan in either direction. The inspection payload, an eddy current probe, moves the length of the scanning axis and then the payload is indexed (i.e., moved a small distance) along the indexing axis. The payload is then moved smoothly back along the length of the scanning axis. Data is collected only during motion along the scanning axis. The scanner has a unique curved track design for maintaining the orientation of the eddy current probe perpendicular to the inspection surface. It allows inspecting the top flat surface and the curved edges of the jet pump beams.

Abstract: A reactor pressure vessel top guide structure inspection and transport system comprising a remotely operable and positionable underwater vehicle for traversing the top guide structure of a reactor pressure vessel and for positioning an inspection system for detecting defects in the top guide structure.

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 carrying out a surveillance program to monitor the neutron fluence and its effect on vessel materials at a position in the annular space between the pressure vessel and core shroud of a boiling water reactor for the purpose of monitoring vessel embrittlement. The apparatus includes an offset capsule holder assembly which fits in an existing capsule holder attached to the inner surface of the pressure vessel wall. The offset capsule holder assembly positions a new capsule holder radially closer to the core, by an amount determined by neutron transport calculations. The new capsule holder is geometrically identical to the original, or a "replacement in kind", allowing the original surveillance capsules to be immediately reinstalled. With the water moderator in the downcomer annulus, the fluence rate increases significantly when the surveillance capsule is moved radially inward from the pressure vessel inside surface toward the core.

Abstract: An ultrasonic flaw detecting apparatus for efficiently detecting a flaw existing in a deep portion of a multi-layer structure includes a first sensor arranged so as to transmit an ultrasonic wave into a different property layer surrounded by a medium having a different acoustic impedance in the multi-layer structure, a function generator for generating a pulse-shaped sine wave, a power amplifier for amplifying and supplying the pulse-shaped sine wave to the first sensor, a second sensor arranged so as to receive a boundary echo from the different property layer, a first amplifier for amplifying the boundary echo received by the second sensor, an intensity detector for judging the intensity of an amplified signal of the boundary echo, a third sensor arranged so as to receive an echo from a flaw inside a layer in a deep portion of the different property layer, a second amplifier for amplifying the flaw echo received by the third sensor, a recorder for recording the amplified flaw echo signal, and a control unit

Abstract: A process and an apparatus for the ultrasonic testing of a component accessible only through a gap, includes driving a carrier accommodating an ultrasonic testing head into an annular gap and bringing the ultrasonic testing head into a position of alignment with the component, for the purposes of repeated testing of components disposed in the poorly accessible gap. Subsequently, the ultrasonic testing head is driven out from the carrier approximately at right angles to the driving-in movement, and is brought into contact with the component. After completing the testing process, the ultrasonic testing head is driven once more into the carrier and brought into a position of alignment with the next component.

Abstract: The device includes a blade (1), one end of which carries a testing probe (2). The probe (2) includes a first ultrasonic transducer (23) constituting an emitter and a second ultrasonic transducer (24) constituting a receiver, which are pivotably mounted at the end of the blade (1) about two axes parallel to the longitudinal direction of the blade (1), arranged separated from one another in the transverse direction of the blade (1), so as to be placed in a narrow annular passage, in contact with a cylindrical wall to be tested, in two positions separated from one another in a circumferential direction of the annular passage.

Abstract: A sensor system for mapping absolute acoustic noise intensity in a three-dimensional acoustic noise field. Localized noise sources within a vessel are extracted using a distant array of transducers mounted on the vessel wall. The absolute intensity can be measured even when totally masked by background noise at the transducer locations. The system includes an integrated transducer installation. Each transducer is an accelerometer which is mounted on the vessel wall using a rigid attachment rod which serves as an ultrasonic waveguide. The output of each transducer is split into low- and high-frequency components, the low-frequency component being a function of the vibrational displacement of the localized portion of the vessel wall and the high-frequency component being a function of the vibrational/ultrasonic waves propagating through the localized portion of the vessel wall.

Abstract: An apparatus for use with a search device and a foreign object extrication device in a steam generator includes a router having two conduits for routing the search and extrication devices, and a positioning mechanism for positioning the conduits. The extrication device may include a cable having a pushing mechanism for pushing a foreign object within the steam generator and a hook mechanism for pulling the foreign object. Alternatively, the extrication device may include a loop mechanism for pulling. The extrication device may include a cable having a slotted end for pushing. Alternatively, the cable may have an anvil for pushing. The router may include a guide tube interconnected with the first conduit for guiding the search device from the tube lane into a selected one of the tube rows of the steam generator and another guide tube interconnected with the second conduit for guiding the extrication device from the tube lane into the selected tube row.

Abstract: An apparatus for positioning a search device and a retrieval device in a steam generator includes a guide mechanism for guiding the devices through the annulus to the tube sheet and drive mechanisms for driving the cables of the devices. Alternatively, a plurality of guide mechanisms and a plurality of drive mechanisms may be provided for a plurality of search and retrieval devices. The guide mechanism may include two double-dog-leg, single-piece, guide tubes between the handhole and the tube sheet for guiding the cables. The drive mechanisms may each include a pair of pinch rollers for driving a corresponding cable, a remote energizing mechanism for independently energizing the corresponding drive mechanism, and a reversible motor having a drive shaft. One pinch roller is driven by one drive shaft and the other pinch roller freely rotates about the other drive shaft. The guide mechanism may also include a guide plate mounted to the handhole and dual sets of guide tubes for the two halves of the tube sheet.

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: 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: A debris box, for use with a search and retrieval device for searching and retrieving a plurality of foreign objects within a heat exchanger, includes a holder mechanism, such as a container, for containing the foreign objects which are retrieved by the search and retrieval device within the heat exchanger; and an insertion mechanism, such as a snake, for inserting the holder mechanism into the heat exchanger.

Abstract: An apparatus for detecting defects comprises a pair of ultrasonic probes which are gimballed onto a pair of elongate members. A pair of yokes are gimballed onto the elongate members. Springs cause an interaction between the yokes and the ultrasonic probes such that the ultrasonic beams travel in a plane parallel to the longitudinal direction of the elongate members. The elongate members are slidably mounted on a carriage and the elongate members are arranged apart at a predetermined angle. The carriage is mounted to travel on an arcuate member to scan the corner of joint between a pressure vessel and a nozzle in a direction radially with respect to the axis of the nozzle. The arcuate member is rotatably mounted to a support member to scan the corner or the joint circumferentially with respect to the axis of the nozzle.

Abstract: A method and an apparatus for in situ ultrasonic inspection of the core spray T-box to thermal sleeve attachment weld and the core spray T-box to cover plate attachment weld in BWRs. The apparatus incorporates a stationary clamping mechanism and sliding and rotational mechanisms which are operated remotely to scan the transducer over the T-box welds and heat-affected zones thereof.

Abstract: An irradiated steel pressurized nuclear reactor pressure vessel 10 is provided with a crack initiation retarding and crack extension retarding reactor vessel integrity girdle 20 or 120 made up of shoes or links 22, with mechanical take up joints (26 to 34a or 126 to 134a). Instead of pivoted shoe links 22, the girdle 120 may be made using constricting roller chain links 122. In any event, crack initiation and crack extension which may result from pressure loading or vessel material embrittled in the beltline region by neutron bombardment is retarded by maintenance of a prestress under the nozzles during all periods of operation of the reactor.

Abstract: Corrosion damage to the tubes of power plant boiler waterwalls is detected by a portable hand-held ultrasonic scanner probe equipped with plurality of dual element transducers having concave cylindrically curved surfaces for simultaneously examining arcuate areas of walls of several tubes as the probe is moved along the waterwall. Tube wall thickness and probe location data are processed by a computer for detection, display and recording of places where significant tube damage has occurred.

Abstract: A method of and an apparatus for measuring the thickness of the overlay clad of the pressure vessel of a nuclear reactor with good accuracy are disclosed. A magnetic yoke having an appropriate length and cross-sectional area of the magnetic path is placed closely in contact with the surface of the overlay clad of the pressure vessel of the nuclear reactor to form a magnetic path by the magnetic yoke and the pressure vessel of the nuclear reactor, the magnetic yoke is magnetized, the distribution of the magnetic field on or near the surface of the overlay clad in contact with which the magnetic yoke is closely placed is measured and the thickness of the overlay clad of the pressure vessel of the nuclear reactor is identified from the medium value or the half value width of the distribution of the magnetic field thus measured.

Abstract: Apparatus for inspecting the nuclear reactor comprising a boom rotatably connected by a pivot point to the top of a reactor head, a mechanism for rotating the boom with respect to said pivot point, a camera affixed to said boom and being slidingly affixed thereto such that the camera may be slidably adjusted in a longitudinal direction with respect to said boom.

Abstract: The length of an object, particularly a spent fuel rod, is measured by taking an optical image of a support surface and then taking an optical image of a fuel rod when placed on the support surface. The two optical images are digitised, stored and then processed to obtain a difference in grey level values between the two stored images. The two images are stored as a plurality of columns each containing pixels having a grey level value. Using an algorithm, the difference between these values in corresponding columns of the two images are determined as root mean square values. The columns are processed in turn to determine which have a root mean square value above a threshold value, these being representative of the presence of a fuel rod. The number of such columns is a measure of the fuel rod length.