Seismic design of a spent fuel storage rack

This paper deals with the design analysis of a spent fuel storage rack performed for a N325 PWR. It concerns the aspect of the problem related to the possible out of phase motion of adjoining modules, whether partially or fully loaded, in case of seismic event. The spent fuel storage rack consists in a certain number of independent rectangular modules free-standing on the pool floor and immersed in water. For studying the seismic behavior of the system, each module is considered as a flexible beam pinned to the pool floor through a rotational stiffness. Using the finite element method, it may be shown that the main vibration mode of a module corresponds to its rotation around the neutral axis of the base plate