Development of automatic ultrasonic inspection system for bent pipes

In Service Inspection (ISI) is performed to confirm the integrity of operating nuclear power plants. ISI, which is mainly an ultrasonic inspection technique, has to be done in a radioactive environment. Therefore, the inspection personnel's exposure to radiation is one of the most serious problems. Many attempts have been made to minimize the radiation exposure. However, ultrasonic inspection of the piping welds, to be performed manually, makes it difficult to reduce the radiation exposure, because of the crammed spatial conditions. In addition, ultrasonic inspection of piping welds is technically difficult, since they often have a very complicated configuration such as pipe bents (elbows). In order to solve the above problems, an automatic pipe inspection system has been developed. The system consists of special probe for bent pipes (including holder units), scanning tool, tool controller, multifunctional ultrasonic instrument, and data processing equipment. The development work of the system and the subsequent functional tests and field tests are described in this paper. (author)