Earthquakes induced sloshing may lead to dangerous effects in a nuclear reactor pool during a seismic events. The objective of this thesis is to investigate sloshing processes in the Advanced Lead Fast Reactor European Demonstrator (ALFRED). Model scale experiments (1:18.4) have been carried out. The model of ALFRED is a reproduction in plexiglass of the very hot plenum of the actual demonstrator, based on Froude number scaling. Distilled water is used in similarity with the lead in the demonstrator. The model consists of an annular tank, as nuclear pool and internal primary core are simply reproduced. In the peripheral, nine cylinders are distributed and represent the internal structures of the demonstrator.