Liquid sodium vessels of sodium cooled fast reactors (SFR) are topped with inert cover gas blanket. Temperature of sodium varies from 200°C to 550°C and due to lower temperature of the roof of the gas space, there exist natural convection loops within the cavity causing convective mass transfer of sodium vapour from the pool surface into the gas space. This coupled with lower temperature of gas away from the sodium pool results in higher sodium vapour concentration than the saturation vapour concentration. At places where the saturation ratio exceeds a critical saturation ratio, nucleation of aerosol droplets occurs. The liquid droplets thus formed can further grow in size due to condensation of vapour on the droplets. Present study is on numerical simulation of generation and distribution of sodium aerosols in the cover gas space using multiphase mixture model. However, the sizes of particles are limited to only two sizes in the present simulation for demonstration of the model.