Effect of Structure-Soil-Structure Interaction on the Seismic Response of the Nuclear Building of Small Modular Reactor

Abstract The seismic Category I structures within the nuclear island of the Small Modular Reactor (SMR) are densely clustered and connected through the underlying foundation soil. This study discusses the phenomenon of structure-soil-structure interaction (SSSI), where the soil medium transmits seismic responses from one structure to its adjacent structures, employing the sub-structuring method. Seismic response analyses are conducted for the nuclear island structures of SMR, with and without considering the SSSI effect. The impact of SSSI on the seismic responses of the nuclear buildings is investigated by comparing their in-structure response spectra (ISRS). The results indicate that SSSI has a minimal influence on the dynamic response for structures with large volumes, as no significant changes are observed in the acceleration response spectra shape, dominant frequency position, peak acceleration, and zero period acceleration value of the ISRS. However, an evident impact is observed on the dynamic response for the standby diesel generator building due to the SSSI effect. Although the response spectra shape remains virtually unchanged, a slight decrease in main frequency is detected after considering the SSSI effect, along with variations in the spectral peak acceleration value and zero period acceleration value to a certain extent.