ABSTRACT
After Fukushima, the question arises, how strongly the nuclear power plants could be impacted by the natural extreme flood events in Switzerland. The Swiss Federal Nuclear Safety Inspectorate (ENSI) requires new investigation from all plant operators in Switzerland in this regard. The two-dimensional modeling of the multi-grain sediment transport considering bed load and suspended load during an extreme event, with an annual probability of occurrence of 10-4, should be considered in such an investigation. The nuclear power plant Gösgen-Däniken AG at the River Aare close to Olten has investigated the impact of the flood event with sediment transport. In order to simulate the sediment transport in the Aare a two-dimensional (2D) model has been adopted. This model is using the finitevolume method based on an unstructured mesh and is performed with the software tool BASEMENT. BASEMENT consists of all necessary modules for such simulations: depth-averaged flow of Shallow Water Equations (SWE) module, 2D bedload transport module and 2D advection-diffusion module for suspended sediment transport. This paper presents the results of the simulations with a special focus on challenges of the modeling and the boundary conditions.
