Hints to discriminate the choice of wet deposition models applied to an accidental radioactive release

Atmospheric dispersion models are especially helpful for nuclear crisis management to anticipate the dispersion of the plume during the first hours following the release and later to analyze the transport and fate of radionuclides. In this process, the modelling of the wet deposition is a crucial point to correctly evaluate the ground contamination. The wet deposition is generally divided in two main different mechanisms, the in-cloud scavenging (rainout) and the below-cloud scavenging (washout). For both of them a large number of models are proposed in the literature reflecting the uncertainties in our understanding of these phenomena. Currently there is no scientific consensus to discriminate between these models. In order to improve our understanding on the magnitude of the modelling uncertainties a comprehensive sensitivity analysis was performed and it focused on the representation of the wet deposition fluxes. A large number of model combinations are evaluated by comParison to the available observations of ground contamination. The hierarchies of models established from different statistical indicators show the lack of robustness of the wet deposition models. The aim is to establish a list of priority parameters for the ground contamination.