Free vibration of a simulation CANDU nuclear fuel bundle structure inside a tube

This paper presents a numerical rigid-elasto model for vibration of a simulation nuclear fuel bundle structure confined in a circular tube.The model is developed using the finite element method combined with the floating frame formulation.The nonlinear dynamic equations are derived using the Lagrange equations.Small-amplitude vibration about the static equilibrium position is obtained through linearization.Numerical results show that the fundamental mode is a rocking-like mode, in which rigid body translation and rotation are coupled with elastic deformations.Gravity is found to reduce the frequency of the fundamental mode without affecting the higher modes.Experiments are conducted for a single fuel bundle structure to validate the numerical results.