The study investigatecl the physical phenomena involved in the aerosols washout by water droplets for thermal hydraulic conditions representative of a severe accident in a PWR simulated into the TOSQAN vessel. A aerosols characterization (WELAS, turbiditimeter) coupled with the spray characteristics measurements (pDA, PIV), provided detailed information allowing to obtain reproducible results showing that aerosols collection dynamics has two phases characterized by two distinct removal rates. The average elementary collection efficiency per aerosols dass was estimated according to the water flow rates and the droplets temperature injection. The comparison between the numerical approach (A5TEC's code) and the experimental results on the collected mass by the droplets showed a good agreement at the test beginning, then a light dissension after a certain time related on the experimental limits of measurernent and the limits of the code.