Experimental study on vertical component isolation system

In Japan, several kinds of three-dimensional seismic isolation system for next-generation nuclear power plant such as fast reactors have been studied in recent years. We proposed a structural concept of a vertical component isolation system, assuming a building adopting a horizontal base isolation system. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by vertical isolation devices consisting of large coned disk springs. In order to verify the isolation performance of the vertical component isolation system, shaking table tests using a 1/8 scaled model were conducted. The test model was composed of 4 vertical isolation devices, common deck and horizontal load support structure. For the design earthquake, the system smoothly operated, and sufficient isolation characteristics were shown. The simulation analysis results matched well the test results, so the applicability of the design technique was verified. As the result, the prospect that the vertical isolation system applied to the FBR plant could technically realize was obtained. (authors)