PRELIMINARY ASSESSMENT OF THE FLUID-STRUCTURE INTERACTION EFFECTS IN A GEN IV LMR

The devastating Fukushima 2011 earthquake and tsunami and their consequent multi-reactor damages in Japan, mainly due to the hydrodynamic effects arisen from the fluid-structure interaction, had a significant impact on the global nuclear energy industry. These events highlighted the need to design the future/existing nuclear installations in order to be able to assure a huge safety level in reference accident configuration and, also, in beyond design conditions. In this framework it is extremely important to analyze the lessons learnt from the Fukushima events and to evaluate the safety margins of the nuclear power plants in particular, under ongoing unexpected severe earthquake, such as a beyond design basis one (BDBE). The aim of this paper deals with the evaluation of the dynamic effects seismically induced by the fluid-structure interaction in an under development Gen IV Liquid Metal Reactor (LMR), specifically with reference to the European reactor configuration. The fluid-structure interaction and sloshing phenomena were numerically analyzed taking into account the non linearities and instabilities due to the influence of material and geometrical parameters. In order to attain the mentioned goal a suitable numerical procedure based on an external coupling between dynamic and structural codes (as MSC.Dytran and MARC) was applied, setting up a detailed 3-D FEM model as well as implementing a specific algorithm capable to analyze the coupling effects between the considered fluid and the structures and the sloshing phenomenon. Numerical results were presented and discussed highlighting the importance of the fluid-structure interaction effects in terms of stress intensity as well as the capacity of internals and vessel walls to withstand wave’s impacts