Analysis and study on vibration characteristics of main steam isolation valve based on simulation and vibration monitoring

Flow-induced vibrations of main steam isolation valves (MSIVs) in nuclear power plants present significant risks to equipment reliability and system safety. Currently, effective fault monitoring techniques and comprehensive analyses of vibration mechanisms are lacking. This paper focuses on the valves of Unit 1 at the Qinshan Phase II Nuclear Power Plant, developing a multi-dimensional analysis framework that integrates "flow field-modal-response-monitoring-prediction." The study employs a combination of methods, including computational fluid dynamics (CFD) flow field analysis, finite element modal calcu lation, on-site vibration measurements, and Long Short-Term Memory (LSTM) trend prediction, to uncover the vibration induction mechanism under fluid-structure interaction (FSI) effects. Through both simulation and monitoring verification, key vibration-sensitive regions and vibration source locations are identified. These findings offer valuable technical support for valve structural optimization as well as for the intelligent operation and maintenance of the system.