The state of Japanese remote technology in nuclear fuel cycle

There are many plants of nuclear fuel cycle in Japan. Fifty-one commercial nuclear reactors are operating. There are also another nuclear plants that include two uranium enrichment plants, five fuel conversion and fabrication plants, two reprocessing plants and other waste management facilities. Some plants are operated, maintained or inspected under a high-level radiation condition because spent fuel and high level radioactive waste are treated. Therefore many kinds of remote technologies have been applied to operation, maintenance and inspection of nuclear plants on the base of the Japanese robotics technologies that have been developed in many manufacturing industries like an automobile one. This paper will report the remote technology for Japanese nuclear plants. In early days of nuclear, repair and inspection robots for nuclear power plant have been developed for reduce of operator's radiation exposure and increase of plant operation ratio. For further technical development, the project named 'Advanced robotics technology' has been carried out from 1983 until 1990 by Advanced Robot Research Association. After this project, each company that was a member of the association applied these developed technologies to nuclear plant. In Tokai reprocessing Plant, a radioactive leakage occurred in one of two dissolvers in April 1982 and the similar leakage occurred in another one in February 1983. JNC examined the leaked dissolver and planned to make repair using remote weld device. After the examinations of weld repair condition, design of devices, manufacturing and mockup test, repair work of the dissolvers started in September 1983 and completed during period of two and a half months. In another case, JNC has adopted full remote maintenance concept in a large cell to Tokai Vitrification Facility and Recycle Equipment Test Facility that will be used as a FBR fuel reprocessing test field. This remote maintenance concept consists of Two-arm Bilateral Servo Manipulator system and In-cell Crane in a large cell. (author)