Current development of insulating cables for nuclear power generating stations

Though ample testing and investigation have been carried out on the engineering safety for nuclear reactors and fuel materials, radiation-resistivity tests have not been taken into consideration for electrical machinery and electric cables, and their testing facilities are not sufficient. Institute of Electric and Electronic Engineering (IEEE) has already established the IEEE standard 323 and 383 (Type testing method for class 1E equipments for nuclear power generating stations) in April, 1974. Further, Nuclear Regulatory Commission (NRC) issued the Regulatory Guide 1.120 (June, 1976), and has endeavored to secure the reliability and safety of cables, in view of the fire accident in Browns Ferry nuclear power station in Alabama occurred on March 22, 1974. While in Europe, active discussion is to be developed on the problems of composite deterioration involving heat, radiation and stress in SC committee of IEC (International Electrotechnical Commission). In Japan, the investigation committee in the Institute of Electrical Engineers of Japan has started regular study. Takasaki Laboratory of JAERI has held regularly ''the meeting for studying the technical criteria on cable materials for nuclear power stations'', associated with electric power companies and major cable manufacturers since the beginning of 1977, to improve technical level. The state of research on the radiation resistance of polymer insulating materials in Takasaki Laboratory is described. Next, necessary conditions and testing methods for cables to be used for nuclear reactors are presented. (Wakatsuki, Y.)