A Substructure-Based Response Spectrum Methodology for Seismic Assessment of Large-Scale Tokamak Components: Implementation and Validation on the CFETR Vacuum Vessel

Seismic safety represents a critical design challenge for large-scale tokamak components in fusion reactors, necessitating robust yet computationally efficient analytical methods. This paper presents a substructure-based response spectrum methodology specifically developed for the seismic assessment of massive tokamak structures, integrating Component Mode Synthesis (CMS) and the Square Root of the Sum of the Squares (SRSS) modal combination scheme within the ANSYS finite element environment. The proposed approach partitions the global structure into manageable substructures, condenses their dynamic characteristics via fixed-interface modal reduction, and efficiently assembles the system response using CMS. Validation against conventional full-model analysis, conducted on the China Fusion Engineering Test Reactor (CFETR) vacuum vessel under multi-directional seismic excitation, demonstrates that the substructure method achieves high computational efficiency, with calculation times reduced by 52.1% to 54.6% across different seismic directions compared to the conventional approach, while maintaining accuracy within acceptable nuclear engineering tolerances. Key results show deviations of less than 1.6% in displacements and 5.5% in stresses compared to full-model benchmarks, with successful identification of critical response regions such as support attachments and port openings. The methodology significantly reduces solution time and resource requirements, offering a practical tool for iterative design and optimization of fusion components without compromising safety standards.