Research on Flow Induced Vibration Characteristics of Plate Fuel Assembly in High-Flow Lead-bismuth Environment

Liquid lead-bismuth alloy has the characteristics of good thermal conductivity and high heat capacity, making it an ideal coolant for the new generation of advanced reactor. In this article, a full-scale computational fluid dynamics (CFD) model for plate fuel assembly in high-flow lead-bismuth environment was established, the transient fluid dynamics analysis based on large eddy simulation (LES) turbulence model was carried out and the fluid excitation force on the fuel plate was obtained. The dynamic analysis model of fuel plate was established, the structural dynamics calculation based on time domain was carried out according to the transient fluid excitation data, and the displacement response of fuel plate was obtained. The calculation results show that the fluid excitation force on the fuel plate in the middle position is much greater than that on the two sides because of the vortex shedding formed by the hoisting structure. The displacement response of the fuel plate concentrates on its own first-order frequency, and the first-order frequency of single fuel plate is much greater than the main frequency of turbulent excitation, so there is no risk of resonance of the fuel plate under fluid excitation. Considering the influence of inlet turbulence intensity, the conservatism of the flow induced vibration analysis method based on rectangular channel power density spectrum may be insufficient. This research can provide a reference for the development of new generation high-performance fuel assemblies.