Study on application of seismic isolation system to ABWR building

This paper reports the result of a study that evaluated the applicability of the seismic isolation system to nuclear power plants. The study focuses on possibilities of a standard design with improved seismic safety of building and equipment for ABWR. A base isolation system with laminated lead rubber bearing was applied in the study. Based on the structural design of isolated buildings, it was confirmed that the design seismic loads can be largely reduced and that seismic elements of buildings and equipment can be easily designed compared with non-isolated buildings. Improvement in the building construction cost and period was also confirmed. The analytical results of seismic probabilistic safety assessments showed that an isolated building has a much higher degree of the seismic safety than a non-isolated building. The study concludes that the seismic isolation system is well applicable to ABWR plants. In addition, with an aim to enhance the earthquake-resistance of future ABWR plants, a building concept was developed, in which a lot of important equipment are laid out on a floor directly supported by the base isolation system. On this plant, further improvement of the seismic reliability is expected due to reduction of the seismic responses of important equipment. (author)