Flow induced damping of a PWR fuel assembly

In the justification of the lateral strength of PWR fuel assemblies under seismic accident, the impact forces on grids are usually the most limiting ones. The knowledge of the fuel assemblies behavior or kinematics is essential in order to compute these maximum loads. The aim of the study is to measure the mechanical characteristics of a fuel assembly in semi-realistic conditions and to extend these measurements to in-core environment. Both experimental tests and theoretical developments are necessary. We present the test conditions and the methods used to determine the fuel assembly characteristics. The nonlinear computations are introduced and commented. (authors)