Investigation on the effect of polydisperse spray droplets distribution on aerosol particles removal efficiency

Aerosol is the primary carrier of fission products in the containment under severe accidents. Spray systems are one of the most effective ways to remove radioactive aerosols. Therefore, it is important to investigate the measures of aerosol particle removal by spray systems under severe accidents. In order to investigate the aerosol removal performance of the spray system in containment under severe accidents, an improved model for predicting the evolution of the aerosol particle with the spray system activation is presented. The presented model allows to simulate the interactions between monodisperse spray droplets and polydisperse aerosol particles as well as polydisperse spray droplets and polydisperse aerosol particles. In this paper, the data of the TOSQAN facility is utilized to validate the developed model, while the model analyzes the effect of the spray system on aerosol particles. The analysis of aerosol removal results shows that the activation of the spray system leads to large aerosol particles more easily trapped by spray droplets, which also causes the aerosol mean diameter to decrease. Analysis of monodisperse droplets demonstrates that small spray droplets are more effective for aerosol removal. For the spray droplet Log-Normal distribution with different standard deviations, the removal rate of aerosol particles is faster when the standard deviation of the spray droplet distribution is larger. Whereas, for the spray droplet Log-Normal distribution with different mean diameters, the removal rate of aerosol particles is faster when the mean diameter of the spray droplet distribution is smaller. The developed model is very useful for predicting the evolution of the fission product aerosol under spray action.

Automated summary

Spray systems are effective in removing radioactive aerosols in severe accidents. In this study, an improved model is presented to predict the evolution of aerosol particles with the activation of the spray system. The model is validated using experimental data and it is found that the activation of the spray system leads to easier capture of large aerosol particles and a decrease in the aerosol mean diameter. The analysis also shows that small spray droplets are more effective in aerosol removal and the removal rate is faster when the standard deviation of the spray droplet distribution is larger or when the mean diameter is smaller.