Session: 05-04: Nuclear Engineering and Safety Analysis

Paper Number: 136085

136085 - Effect of Structure-Soil-Structure Interaction on the Seismic Response of the Nuclear Building of Small Modular Reactor 

Abstract: 

The structures on the same construction site are typically interconnected through the foundation soil layer. During an earthquake event, the interaction between a structure and the surrounding soil is transmitted through the foundation, influencing neighboring structures while being influenced by their own interactions with the soil. As a result, the dynamic characteristics and seismic response of a group of structures on a site differ from those of individual structures. Therefore, it is crucial to analyze the dynamic interaction between adjacent structures, known as Soil-Structure-Soil Interaction (SSSI), which represents an extension of traditional research on Soil-Structure Interaction (SSI).

In the nuclear power industry, the SSSI effect is often disregarded in the calculation of in-structure response spectra (ISRS) due to computational limitations of analytical tools. As a result, the investigation into the impact of the SSSI effect on seismic response of nuclear island buildings is still in its early stages of research. However, upon examining the layout scheme of a small modular reactor (SMR) , there is only a 100 mm separation between plants within the nuclear island area. The close proximity of the plant and significant variation in volume necessitate considering the transmission of vibration effects from neighboring plants through the foundation medium during seismic analysis of a single plant. This can result in significant alterations in the plant's response at specific frequencies.

This study provides a concise description of the fundamental principle governing the motion of SSSI system in substructure method, while shedding light on the primary factors contributing to the dynamic interaction between adjacent structures. Subsequently, an investigation is conducted on the influence of SSSI on the seismic response of SMR nuclear island structures. By comparing the ISRS results with and without SSSI at key elevations, the following conclusions can be drawn.

Firstly, the presence of a densely clustered group of plants has minimal impact on the dynamic response of a relatively large nuclear island facility, as evidenced by the negligible alteration to the shape and position of the acceleration response spectrum, peak acceleration, and zero-period acceleration.

Secondly, the shape of the response spectrum remains virtually unchanged; however, the dominant frequency of the structure will decrease after SSSI activation. A significant shift of the response spectrum curve towards the left is observed, accompanied by varying degrees of increase or decrease in spectral peak acceleration and zero-period acceleration.

The findings of this study are derived from the site conditions of the SMR demonstration project. The dynamic interaction between structures is influenced by numerous factors. In addition to the structural layout and size, both the structural spacing and ground characteristics contribute to the SSSI action. Future research can explore the governing principles of SSSI effect more comprehensively through further parameter sensitivity analysis.

Presenting Author: Dongyang Wang China Nuclear Power Engineering Co.,Ltd.

Presenting Author Biography: Dongyang Wang, Ph.D., senior engineer, whose research field is seismic response analysis of nuclear engineering structures.

Authors:

Dongyang Wang China Nuclear Power Engineering Co.,Ltd.
Xiaoying Sun China Nuclear Power Engineering Co., Ltd.
Chaoqi Zhang China Nuclear Power Engineering Co.,Ltd.