Takahiro Shimada

Study on Three-Dimensional Seismic Isolation System for Next-Generation Nuclear Power Plant: Hydraulic Three-Dimensional Base Isolation System

In Japan, a number of three-dimensional base isolation systems have been studied for application to new nuclear plant concepts such as the FBR, but these efforts have not so far yielded practically applicable results. The impeding factor has been the difficulty of obtaining an adequate capacity on the vertical isolator for supporting the mass of an actual structure and for suppressing rocking motion. In this paper, we propose a new three-dimensional isolation system that should solve the foregoing problem. The system is constituted of a set of hydraulic load-carrying cylinders connected to accumulator units containing compressed gas, a set of rocking-suppression cylinders connected in series, and a laminated rubber bearing laid under each load-carrying cylinder. The present paper covers a basic examination for applying the proposed system to a FBR plant now under development in Japan. In order to verify expected system performance, the load-carrying cylinders were first tested independently of rocking-suppression cylinders, and this was followed by integrated dynamic test of the system incorporating both load-carrying and rocking suppression cylinders. Response analysis reflecting the test results has indicated the proposed system to be well applicable to the envisaged commercialized FBR. The study was undertaken as part of a research and development project sponsored by the government for realizing a three-dimensional seismic isolation system applicable to future FBR.Copyright

Feasibility Tests on a Three-Dimensional Base Isolation System Incorporating Hydraulic Mechanism

In Japan, a number of three-dimensional base isolation systems have been studied for application to new nuclear plant concepts such as the FBR, but these efforts have not so far yielded practically applicable results. The impeding factor has been the difficulty of obtaining an adequate capacity on the vertical isolator for supporting the mass of an actual structure and for suppressing rocking motion. In this paper, we propose a new three-dimensional base isolation system that should solve the foregoing problem. The system is constituted of a set of hydraulic load-carrying cylinders connected to accumulator units containing a compressed gas, another set of rocking-suppression cylinders connected in series, and a laminated rubber bearing laid under each load-carrying cylinder. The present paper covers a basic examination for applying the proposed system to a commercialized FBR now under development in Japan, together with static and dynamic loading tests performed on a scale model to verify expected system performance. Response analysis reflecting the test results has indicated the proposed system to be well applicable to the envisaged commercialized FBR. The study was undertaken as part of an R&D project sponsored by the government for realizing a three-dimensional seismic isolation system applicable to future FBR’s.Copyright