Analysis of impact phenomena between PWR fuel assemblies in earthquake situations

To qualify fuel assembly seismic resistance and to promote the development of new grid designs, FRAMATOME (Fuel Division) in cooperation with CEA have launched a large scale experimental program which will lead to the design of improved models for safety analyses. The tests performed on full scale mock-ups were devoted to analyse: - the vibratory behaviour (frequency, damping) of the fuel assembly as a function of two important parameters: the motion amplitude and the holddown force. The effect of the fluid on these characteristics has been also investigated. - The behaviour of the assemblies during impacts (impact against a rigid wall and impact between two assemblies). The aim of this paper is to present the main results of these tests and the modelisation of the fuel assembly, developed to interpret these tests. Some correlations between experimental and calculation results will be shown