Using recently established intelligent mobile robot theory and high technologies in computer science, we have designed an inspection automation system for welded parts of the reactor vessel, and we intend to establish basic technologies. The recent status of those technologies is surveyed for various application areas, and the characteristics and availability of those techniques such as intelligent mobile robot, digital computer control, intelligent user interface, realtime data processing, ultrasonic signal processing, intelligent user interface, intelligent defect recognition, are studied and examined at first. The high performance and compact size inspection system is designed, and if implemented, it is expected to be very efficient in economic point of view. In addition, the use of integrated SW system leads to the reduction of human errors. Through the analysis results and experiences, we investigated the further feasibility of basic technology applications to the various similar operation systems in NPP. (Author).