Apparatus and process for simultaneously positioning and oscillating a

Abstract

An apparatus and process for positioning and for simultaneously oscillating a plurality of heater probes within a plurality of heat exchanger tubes mounted in a tubesheet of a nuclear steam generator is disclosed herein. The apparatus generally comprises a frame, a plurality of probe drivers mounted onto the frame, wherein each driver includes a pneumatically operated, bladder-type gripper for selectively gripping and ungripping the push-cable of one of the heater probes, as well as an oscillating mechanism powered by a variable voltage d.c. motor. A controller connected between the d.c. motor and a power source separately controls the frequency and the amplitude of the cycle that the oscillating mechanism moves the gripper in, and further controls the alignment between the midpoint of the oscillatory cycle and a selected point along the longitudinal axis of the tube. The apparatus is movable to a selected position on the tubesheet by means of a robotic arm, and includes a coupling for remotely attaching and detaching the arm from the frame of the apparatus. The frame of the apparatus includes a pair of opposing cam-locks for detachably securing the apparatus at a selected position on the tubesheet, thereby advantageously freeing the robotic arm that delivered the apparatus. Finally, the frame is contoured to the shape of the inner walls of the steam generator so that the apparatus can service heat exchanger tubes located on the periphery of the tubesheet.