LAUSR

Abstract The prediction of fuel rod vibration is of importance in the designing of reactor core. A precise simulation of the vibration amplitude of fuel rods is necessary. It is disappointed that the mode shape equation of a spring-supported fuel rod with multi spans is not available in previous literature, due to the singularity of coefficient matrix. In this work, a theoretical model for the vibration of spring-supported rod with multi spans is established. The fuel rod is assumed to be a homogeneous beam. The flexural displacement of the rod is represented as the combination of Fourier series and auxiliary trigonometric functions in order to overcome the discontinuity and singularity of mode shape. The vibration frequency and mode shape are obtained. The calculation results are in satisfactory with theoretical results. The variation of spring constant and its effect could be simulated.