Research and Development of Three-Dimensional Isolation System

Abstract

The design basis ground motions have been revised to improve the seismic resistance of nuclear power plants. The reduction of seismic forces not only horizontally but also vertically has required more critical than in the past to ensure the seismic resistance of components. Notably, the design of a Sodium-Cooled Fast Reactor will require reducing the seismic forces applied to the components because of the components with thin wall thickness. To overcome this problem, the authors have been developed an innovative three-dimensional seismic isolation system. This seismic isolation system will be applied to the reactor building, as the isolated reactor building. Investigating the force and displacement relationships of this seismic isolation system is an essential process to verify the feasibility of the design for the isolation system. The static loading tests were conducted to verify the force and displacement relationships in horizontal and vertical directions, which used a half scale three-dimensional isolation system. This paper demonstrates that the horizontal supporting function enables a stable load path and the independence of the force and displacement relationships in horizontal and vertical directions to ensure even under simultaneous horizontal and vertical loading assumed in the design basis ground motion.