Reliability analysis of impeller and shaft system in shaft-sealed reactor coolant pump

This study addresses the reliability issues of the axial seal main pump (RCP) impeller and shaft system under high-temperature and high-pressure water conditions. It employs fluid–structure interaction (FSI) theory and modal analysis to conduct a systematic study of dynamic characteristics and fatigue life. Using FSI simulation model, this study compares the natural frequency variations under dry and wet modal conditions to reveal the influence of added water mass on structural dynamics. Transient dynamic stress calculations are completed on the ANSYS Workbench platform. The fatigue life of the impeller is predicted using Miner’s linear cumulative damage theory and nCode DesignLife software. The results indicate that most regions of the impeller have a lifespan exceeding 7.223 × 10¹⁰ cycles (approximately 92.5 years). Localized fatigue risks are identified only at the blade roots. Campbell diagram analysis shows that the rated speed of the nuclear main pump avoids the main resonant critical speeds, but attention should be paid to the influence of low-frequency excitation on stability. The findings of this study provide a theoretical basis for the structural optimization and reliability enhancement of nuclear main pumps.