Random Response Analysis of PWR Fuel Rod Effect on Axial Flow

Based on random vibration theory, the random response analysis method of PWR fuel rods under axial flow was established. The fluid force along the axial of rod was treated as a fluctuant random load, and the mode shape method and power spectrum analysis method were used to derive the empirical formula of RMS response. This article provides a theoretical analysis method which does not rely on the flow induced vibration test of fuel assembly. The effects for the RMS response of fuel rods by the equivalent velocity, turbulence intensity, and correlation length factor were discussed. The method can meet the requirements of engineering analysis. The results show that the RMS response of fuel rods will increase with the equivalent velocity, turbulence intensity and the correlation length factor. The response is more sensitive to the equivalent velocity and coefficient length factor changes, and linearly with the turbulence intensity. In the operating condition of the pressurized water reactor (PWR), the RMS amplitude of fuel rods is about micrometers.