Session: SE-02-01 Seismic Isolation

Paper Number: 153210

153210 - Performance Evaluation of Floating Seismic Isolation System 

Abstract: 

Floating-type nuclear plants have been studied, and in some cases deployed, as marine systems. Although horizontal components of seismic waves may be naturally isolated from the floating plant due to little transfer of shear forces in water, the vertical component can propagate through water to the plant from seafloor in what is called a “seaquake” phenomenon.

A concept of floating seismic isolation system (FSIS) has been proposed by the authors. The FSIS is a unique seismic isolation mechanism having a number of cavities and orifices embedded in the bottom of the floating structure. The cavity is designed to reduce peak vibration response of the structure to vertical seismic input whereas the orifice is used to add damping for residual vibration reduction,

 A series of shaking tests to verify the performance of FSIS have been recently completed on the 3D Full-Scale Earthquake Testing Facility called "E-Defense" in Japan. The test model is a 1/15 scale mockup down-sized by similarity from a FSIS-paired SMR plant design for floating in a pool. The peak acceleration input is up to 1.3G horizontally and 1.0G vertically with three sets of frequency spectra selected from among the most significant earthquakes recorded in Japan.

This paper presents post-test analysis of the measurements and evaluation of the seismic isolation potential of the FSIS. The results presented herein support that the FSIS can reduce seismic responses of a floating nuclear reactor plant by substantial levels in horizontal and vertical directions.

Presenting Author: Takashi Mori IHI Corporation

Presenting Author Biography: The author obtained a Master's degree from Kyoto University Graduate School. Since 2018, he has been working at IHI Corporation, where he has been engaged in the seismic evaluation and development of base isolation devices for cranes and unloaders used in nuclear and coal-fired power plants, utilizing advanced seismic and base isolation technologies.

Authors:

Takashi Mori IHI Corporation
Takahiro Shimada IHI Corporation
Haruki Motegi IHI Corporation
Satoru Kai IHI Corporation
Akihito Otani IHI Corporation
Tomohiko Yamamoto Japan Atomic Energy Agency
Xing L Yan Japan Atomic Energy Agency