Remote automated ultrasonic inspection: New approaches to reduce radiation exposure and shorten inspection time

Since 1977 General Electric (GE) has pioneered the use of trackless, remote inservice inspection (ISI) for boiling water reactor (BWR) vessels. Eleven baseline inspections and two inservice inspections have been performed using four different inspection systems. Since the first GE remote ISI system was placed into service in 1977, many advances in the technology have been made and development work is continuing. This paper describes some of those advances, and the development work currently in progress. The basic operating principles of the GE remote ISI system remain unchanged from the original concepts: a trackless vehicle featuring magnetic wheels is used for reactor pressure vessel (RPV) weld inspection, and removable tracks are used for nozzle inspection. Location on the RPV surface is accomplished by acoustic emission (AE) principles, ie., acoustic triangulation while vehicle positioning control, scanning and mapping of indications are done by a precision digital encoder guidance system. All of the above systems and the inspection itself, are controlled by a minicomputer