Abstract:
This study focuses on the modular design and construction technology of generation III nuclear power plants (NPP), with particular emphasis on design specifications of steel-concrete-steel (SCS) structures, modular construction techniques, and seismic performance evaluation of pile rafted small modular reactors (SMRs). Based on the Technical Standard for Steel Plate Concrete Structures in NPP (GB/T 51340-2018) issued by China, the excellent mechanical and seismic performance of SCS structures under static and seismic loads was validated. Specifically, under a 0.3g safe shutdown earthquake (SSE) level, the steel plates remained elastic, and concrete cracking did not lead to structural failure. Modular construction technology, incorporating 3D laser scanning and digital pre-assembly methods, significantly improved construction accuracy and efficiency, thereby reducing the construction period. Furthermore, large-scale shaking table tests were conducted to investigate the seismic response characteristics of the sandy sites-pile rafted foundations-SMR structures system. The results demonstrated that the pile rafted foundations effectively filtered high-frequency components of seismic loads, significantly reducing acceleration sensitivity, and enhancing the overall seismic performance. In nuclear island building test model, horizontal acceleration amplification effect was most pronounced in external plant and internal nuclear equipment components, while internal steel containment vessel component exhibited a weaker acceleration amplification effect due to the top weight. Seismic response spectrum analysis further revealed that the combined action of pile rafted foundations and superstructures significantly altered the frequency characteristics of the test model, underscoring the critical role of pile foundations in improving the seismic performance of SMR structures. The new findings of this study provide important theoretical and technical supports for the modular design as well as seismic performance evaluation and optimization of NPP in nonrock sites.