Gonzalez Merino, AlbertoAlbertoGonzalez MerinoCostas de la Peña, LuisLuisCostas de la PeñaGonzález, ArturoArturoGonzález2016-08-222016-08-222016-07-30http://hdl.handle.net/10197/78109th International Youth Nuclear Congress (IYNC 2016), Hangzhou, China, 24-30 July 2016High Density Spent Fuel Storage (HDSFS) racks are structures designed to hold nuclear spent fuel assemblies removed from the nuclear power reactor after having been irradiated. They are used in the first step of the waste management process, during the wet storage. The underwater seismic response of HDSFS racks is a troubling safety issue. Since they are 12 m submerged free standing multi-body structures loaded with radioactive fuel, their design remains as complex as crucial [1] [2]. The design deals with a Fluid-Structure Interaction (FSI) problem, a transient dynamic response and a very highly nonlinear behaviour. Several cost-effective industrial approaches have been used in these calculations to date, but some dispersion of results still exists. Therefore, the regulatory authorities are requiring an evaluation of the uncertainties in the methodology. Equipos Nucleares, S.A. (ENSA) is a worldwide expert in racks design and construction [3] and has recently launched a research project to improve the understanding of the phenomena. The latter is funded by the European Comision1 and aimed to identify, evaluate and reduce the uncertainties involved in the calculations. In this paper, the state of the art and the current sources of uncertainty are discussed.enRacksFree-standingFEMDynamic analysisNonlinearFluid-structure interactionHydrodynamic massConference Publication2016-08-09https://creativecommons.org/licenses/by-nc-nd/3.0/ie/