Abstract: An improved robotic arm system for servicing the tubesheet located within the channel head of a nuclear steam generator is provided. The system includes a robotic arm whose shoulder and elbow joints are rotatable only in the plane parallel to the tubesheet in order to eliminate the imposition of cantileverly-induced torques on the electric motors driving these joints, as well as to minimize the possibility of mechanical interference between the arm and the walls of the channel head. Each of the motorized joint assemblies of the arm includes resolvers connected not only to the output of the drive train that moves the joint, but also to the drive shaft of the electric motor that drives the drive train, wherein the feedback signal generated by the resolver connected to the drive shaft of the electric motor is the primary signal used to modulate the amount of electric power conducted to the motor of the joint. Such a configuration advantageously results in smoother robotic arm movement.

Abstract: A flexible hardrolling mandrel for expanding a sleeve within a tube of a nuclear steam generator is disclosed herein. The flexibility of the tool facilitates the insertion of the tool into tubes of the nuclear steam generator that have only a limited accessibility, and the tool is designed to transfer sufficient torque as required for hardrolling by way of the flexible design. Generally, the hardroll mandrel assembly includes an elongate housing with flex joints along its length, a roller cage rotatably mounted to the housing supporting at least one roller, a tapered actuator shaft slidable within the roller cage to extend the roller, a flexible inner shaft connected to the actuator shaft and drivingly connected to the housing near the roller cage, and an end effector and drive device for imparting torque to the housing.

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 vehicle and its control system is disclosed for inspecting or servicing a remote limited access location. The vehicle has a drive frame comprised of first and second opposing legs, and third and fourth opposing legs pivotable connected to the first and second legs to form a parallelogram. A drive mechanism is interconnected between the first and second legs of the parallelogram drive frame for opening and closing the drive frame. First and second attachment devices, illustratively in the form of magnets, are also attached to the first and second legs. The vehicle control system taking the form of a programmable computer in an illustrative embodiment of this invention responds to the opening and closing of the drive frame for alternatively actuating and deactuating the first and second attachment devices, whereby the vehicle is controllably driven.