Abstract: A laser welding apparatus and method are used to weld the inner surface of small diameter tubes such as nuclear heat exchanger tubes. A weld filler metal carried by a rotatable laser weld head is fed into the weld zone to produce deeply penetrating weldments of low profile. The apparatus and method can effectively be used to repair cracks in heat exchanger tubes to thereby provide extended service life.

Abstract: System and method for laser welding an inner surface of a tubular member, which tubular member may be a repair sleeve disposed in a nuclear heat exchanger heat transfer tube. The system includes a laser for generating high intensity laser light sufficient to fuse the sleeve to the inside diameter of the heat exchanger tube, the tube being of the type typically found in nuclear heat exchangers. A fiber-optic cable is optically coupled to the laser for conducting the laser light therethrough. The fiber-optic cable has a predetermined configuration to homogenize the laser light so that the laser light obtains the desired spatial coherency as the light is emitted from the fiber-optic cable. A mirror is optically coupled to the fiber-optic cable so as to receive the homogenized light beam emitted from the fiber-optic cable.

Abstract: A frame is coupled to a remotely operable service arm (ROSA), and a rotatable carousel, in turn, is carried by the frame to position several tool modules used in a welding operation adjacent to a damaged tube in a tubesheet of a nuclear steam generator. The arm positions an alignment module directly beneath the damaged tube and the module aligns the carousel. The carousel is rotated to sequentially align and register a laser welding module, a cleaning module, and an inspection module with the damaged tube for a welding operation on a lower portion of the damaged tube in the tubesheet area. One embodiment for the alignment module has a pneumatically operated pin which is operator controlled, and which has an increasing diameter from its distal end to obtain a gross to a vernier alignment of the carousel and, thus, a proper alignment for the remaining modules. A further embodiment provides an alignment pin which is automatically computer controlled without operator intervention.

Abstract: System and method for laser welding an inner surface of a small diameter tubular member. The system includes a laser for generating laser light and a mirror optically coupled to the laser for reflecting the light onto the inner surface of the tubular member to laser weld the inner surface of the tubular member. A rotator assembly is connected to the mirror for rotating the mirror in order to weld around the inner surface of the tubular member. The mirror and rotator assembly are each sized to be disposed in the tubular member at a location adjacent the portion of the tubular member to be welded. The rotator assembly has a spiral groove formed in the exterior thereof for receiving a cord wrapped around the exterior of the rotator assembly. An end of the cord is connected to a motor located externally to the tubular member, so that the cord is pulled as the motor is operated. As the cord is pulled, the rotator assembly rotates for rotating the mirror.

Abstract: Both a system and method are provided for laser welding the inner walls of conduits, such as the sleeves used to repair the heat exchanger tubes of nuclear steam generators. The system generally comprises an elongated tubular housing, a fiber-optic cable for conducting remotely generated laser light into the tubular housing, a beam deflection mechanism supported within the distal end of the tubular housing and including a rotating mirror for radially reflecting and focusing light received from the fiber-optic cable around the inner wall of the sleeve, and a tracking assembly mounted on the distal end of the tubular housing for maintaining a constant radial distance between the mirror of the beam deflection mechanism and the inner wall of the sleeve despite any irregularities which may be present in the roundness of the sleeve.

Abstract: A flexible, hose-like delivery system for positioning and rotatably supporting a probe which may be a pancake-type eddy current probe at a desired position along the longitudinal axis of a small-diametered conduit such as the heat exchanger tube in a nuclear steam generator is disclosed. The system comprises a flexible inner shaft formed from a plurality of short segments of Bowden shafting which is connected to a drive train located remotely from the interior of the heat exchanger tube, a flexible outer housing preferably formed from a plastic conduit concentrically disposed around the inner shaft, and a plurality of ball bearing assemblies which interconnect the short shaft segments for minimizing the frictional engagement between the inner shaft and the interior walls of the flexible outer housing.

Abstract: System for inspecting the interior of tube plugs, particularly tube plugs of the type having expander elements disposed therein. The system includes a probe assembly connectable to the tube plug, the probe assembly having a rotatable and translatable probe carrier housing for housing a sensor probe capable of inspecting the tube plug. The probe assembly also includes a leaf spring extending through the probe carrier housing and attached to the sensor probe for radially outwardly biasing the sensor probe into sensing contact with the interior of the tube plug, particularly the interior of the tube plug located between the top of the tube plug and the expander element. A tangle-free flexible hose is connected at one end thereof to the probe carrier housing for transversely rotating and longitudinally translating the probe carrier housing. The flexible hose is also connected at the other end thereof to a probe driver assembly that rotates the flexible hose which in turn rotates the probe carrier housing.

Abstract: Both a system and method for laser welding the inner surface of a metallic tube, which may be a sleeve inside a heat exchanger tube of a nuclear steam generator, is disclosed. The system comprises an elongated tubular housing that is insertable within a reinforcing sleeve disposed within a heat exchanger tube, a laser unit for generating a beam of light, a fiber optical conduit for conducting light from the laser unit through the interior of the tubular housing, a beam deflection assembly including a mirror canted at an angle of 45.degree. that is rotatably mounted on the distal end of the housing and optically connected to the fiber optical cable, and a remotely powered rotary drive assembly for rotating the beam deflection assembly to direct laser light around the inner surface of the tube that includes a transducer for converting linear to rotary motion.

Abstract: A system for helically driving an inspection probe within a tube of a nuclear steam generator is provided, wherein the system is particularly useful in driving a combination eddy-current and ultrasonic probe. The system generally includes a head assembly insertable with the tube for inspection, a drive frame assembly to be located external of the steam generator, and a conduit system connecting the head assembly and drive frame assembly. Particularly, the head assembly includes a portion fixable to the tube by a pressure bladder and a movable portion helically movable with a probe to the fixable portion. The drive motor and electrical pick-up are slidably movable on the drive frame assembly to move linearly with the probe during inspection so as not to limit the stroke of the probe, wherein the drive motor and pick-up are connected with the head assembly by way of two flexible coaxial conduits.

Abstract: An apparatus and method for remotely inserting and positioning a sleeve-loaded mandrel within a damaged tube mounted in the tubesheet of a nuclear steam generator is disclosed herein. The apparatus of the invention generally comprises a frame, a mounting mechanism for detachably and pivotally mounting the frame to the open end of one of a first tube in the tubesheet, an advancing assembly supported by the frame for remotely inserting and advancing the sleeve-loaded mandrel to a position across a damaged section of the selected tube, and a drive train for pivotally positioning the advancing assembly into alignment with the open end of the selected tube. In the preferred embodiment, the advancing means is formed from the pair of hydraulically operated grippers, one of which is reciprocably movable with respect to the other.

Abstract: A tool for inserting sleeve blanks in damaged steam-generator tubes of light weight capable of being manipulated by ROSA, a remotely operated service arm. ROSA permits the tool to be attached externally of the channel head of the steam generator.The tool includes a fixed gripper and a moveable gripper. The gripping member of each gripper is a flexible sheet or bladder which conforms readily to the surface being engaged. For insertion, the sleeve blank is mounted on a mandrel. The insertion is carried out by operating the grippers repeatedly through the following cycle until the sleeve blank is inserted into the damaged tube:(a) The moveable gripper is set in the lowermost position.(b) The fixed gripper is open.(c) The moveable gripper engages the sleeving assembly.(d) The moveable gripper raises the sleeving assembly to the uppermost position.(e) The sleeving assembly is engaged by the fixed gripper.(f) The moveable gripper is disengaged from the sleeving assembly.

Abstract: An improved heater assembly and method for applying a brazing heat across a selected longitudinal section of a tube is disclosed herein. The heater assembly generally comprises a heater mandrel having an electrical resistance heating element coiled thereabout, and a support mandrel for supporting and centering this heating element. The heater mandrel further includes a means for directing a flow of inert gas in the space between the coiled heating element and the inner walls of the tube being brazed in order to purge this space of ambient atmospheric oxygen and prevent the heater mandrel from oxidizing. The support mandrel includes a centering means in the form of two roller assemblies, each of which has three spring-loaded rollers equidistantly spaced 120.degree. around its diameter. In the method of the invention, the heater mandrel is inserted into the tube and slid across the longitudinal section to be brazed.

Abstract: An improved apparatus and process for rotopeening metallic conduits of limited accessibility, such as the peripherally located heat exchange tubes around the tubesheet of a nuclear steam generator, is disclosed herein. The bowl-like inner wall which lies directly adjacent to such peripherally-located tubes renders it difficult to insert a rotopeening spindle into the open ends of these tubes in order to work-harden these tubes in the tubesheet region. Generally, the apparatus of the invention comprises at least one flexible rotopeening spindle, an advancing mechanism for remotely and incrementally advancing the flexible spindle through an open end of a selected peripheral tube, and a frame for supporting both the flexible spindle and the advancing mechanism. The length of the advancing mechanism is substantially shorter than the length of the flexible spindle so that the spindle and the advancing mechanism may be easily placed into a peening position with respect to the most remotely located tubes.

Abstract: A gripper assembly whose gripping member is a thin (0.050" to 0.060") pliable elastometer, typically of a Pelethane compound having high coefficient of friction with respect to the surface to be gripped. The assembly includes a hollow retainer formed of abutting retainer sections. Internally the sections form a circularly cylindrical surface. The gripping member is circularly cylindrical and is mounted on the retainer so that it extends over the internal cylindrical surface. The ends of the gripping member have rings which are sealed pressure-tight in slots in the end surfaces of the retainer. Within the gripping member there is a cage formed of rods joined by rings for centering an object to be gripped by windows and defined between the rods and rings of the cage. The retainer has a port through which a fluid (air) under pressure is injected.

Abstract: Both an apparatus and a process for accurately applying a correct amount of brazing heat to a conduit are disclosed herein. The apparatus generally comprises a mandrel including an electrical resistance wire heating element and a heat sensor for sensing the temperature of the inside walls of the conduit which were heated. The mandrel is preferably formed from a refractory material, and the heat sensor is located beneath the surface of the mandrel in order to insulate it from heat radiated from the electrical resistance wire wound about the mandrel body. The mandrel further includes an opening in the portion of the mandrel which surrounds the heat sensor in order that the sensor may be selectively exposed to a section of conduit to which heat was applied by sliding the mandrel to a position which aligns the opening with the wall of the heated conduit. The temperature of the conduit may then be determined as a function of the radiant heat received by the heat sensor.

Abstract: The hollow tubular member or blank which is to serve as a sleeve for a corroded tube of the steam generator of a nuclear reactor plant and which is too long to be manipulated under the tube sheet of the reactor, is prebent into a shape such that it can be manipulated and is then progressively straightened under the tube sheet as it is progressively inserted into the tube. The straightener includes a plurality of grooved rolls mounted staggered and rotatable in a train. Each roll forms a channel engaging half of the periphery of the member. The contour of the engaging surface of each roll is the same as the contour of the member over half of its peripheral surface so that each roll mates with the member over half of its peripheral surface.