A novel component mode synthesis-proper orthogonal decomposition-reduced-order model for flow-induced vibration prediction of nuclear fuel rods using limited measurement samples

Flow-induced vibration of nuclear fuel rods is a critical issue affecting the structural integrity, operational safety, and long-term reliability of advanced nuclear energy systems. However, high-fidelity fluid–structure interaction simulations required for accurate flow-induced vibration prediction are often computationally expensive, limiting their use in rapid assessment and design optimization. To address this challenge, this study proposes a reduced-order model based on component mode synthesis and proper orthogonal decomposition for reconstructing full-field flow-induced vibration responses of fuel rods from sparse measurements. The fuel rod is first partitioned into subcomponents according to the locations of measurement and target points, and the structural degrees of freedom are reduced using the Craig-Bampton component mode synthesis method. Static loading cases are then designed to construct snapshot matrices, from which dominant modes are extracted. Based on sparse measured displacement responses, the corresponding mode coefficients are identified through Tikhonov regularization, enabling efficient prediction of full-field dynamic responses. The proposed method is applied to circular and helical cruciform fuel rods immersed in lead–bismuth eutectic coolant. Results show that the method accurately predicts both natural frequencies and flow-induced vibration responses, achieving model reduction ratios of 98.21 percent and 97.81 percent, respectively. Even under 20 percent measurement noise, the coefficients of determination remain as high as 0.957 and 0.934, demonstrating strong robustness and prediction accuracy. The proposed method provides an efficient and reliable tool for rapid flow-induced vibration response prediction and can support the vibration-resistant design and safety assessment of nuclear fuel rods in advanced energy systems.