Development of advanced ultrasonic inspection system for nuclear power plant reactor vessels

An ultrasonic inspection machine consisting of large and stiff columns and guide rails has usually been used in the pre-service inspection (PSI) and inservice inspection (ISI) of nuclear power plant reactor vessels. However, the machine is so large and heavy that maintenance and handling are different. To solve these problems, our robotics technology and experience from reactor vessel II have been applied to develop a new second generation machine that can dramatically reduce the critical path time of reactor vessel II. This system is characterized by the following features: (1) It can move automatically and can set its position accurately using under-water positioning system; (2) Inspection is made by an articulated manipulator which is high-rigid and accurate; (3) The total weight is approx. 300 kg in air (O kg underwater), so the plant's polar crane is not required during inspection. We have fabricated a prototype machine to test a full scale mock up of the reactor vessel