The present paper exposes the main directions of a R&D program that DCN and CEA are currently developing to study the dynamic response of the steam generator of a naval nuclear propulsion reactor submitted to a shock. The structure is composed of tube bundles, immersed in a two phase flow fluid (steam and water). The dynamic solicitation contains high accelerations and high frequencies. It is thus necessary to establish which kind of physical phenomena can take place, and which kind of numerical tool can be used to study the dynamic behavior of the system. If the acceleration and the frequencies are very high, it will be necessary to consider highly non linear physical phenomena, with large deformation within short time duration. If the acceleration and (or) the frequencies are lower, simpler methods can be considered, assuming a linear behavior for the structure. In the latter case, as the frequencies still remain higher than the seismic ones, it might be necessary to take into account different kind of eigenmodes, as those depending on the fluid compressibility. As the fluid is a two phase medium, the use of homogenized fluid model has to be investigated. Since the tube bundle is a periodic structure, a homogenization technique can be used. Basic principles of the method are recalled as well as potential developments of existing methods. Influence of dissipative effects has also to be evaluated. The paper exposes the various problems that have to be addressed in order to produce a physical model of the structure that takes into account the various fluid-structure interaction effects for the shock analysis of the steam generator.

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