Development of FBR piping bellows joints in Japan

For the practical use of fast breeder reactors (FBRs) reduction of construction costs is one of the most important factors. If the long and winding route of piping systems (needed to absorb the thermal expansion) can be shortened and simplified, sharp reductions in related apparatus, equipment and reactor building etc. can be expected (especially in the case of loop type FBRs). The use of bellows joints, which possess good ability to absorb thermal expansion, is one of the best means of shortening the piping system. From 1983 to 1988, the Power Reactor and Nuclear Fuel Development Corporation promoted extensive research and development on FBR piping bellows joints, which covered areas such as strength evaluation methods, manufacturing and inspection techniques, maintenance and repair techniques, investigation of safety logic etc. The purpose of that work was to ensure that the application of bellows joints to FBR main piping systems was a technical and practical possibility. The conclusion was that the use of FBR piping bellows joints was feasible. Consequently, both draft structural design rules and draft manufacturing and maintenance rules were formulated based on the results. This paper presents a summary of the program and the results of the research and development. (orig.)