Entraining of dust and steam flux in water pool: Experimental and numerical simulations of vapor condensation and dust deposition

This paper deals with experimental tests of steam condensation in a water pool at atmospheric pressure and temperature in the range 15-100 °C. The activity is performed in the frame of a research program, funded by the ITER organization, for the study of dust deposition, produced in the ITER Vacuum Vessel and entrained by the steam and non condensable gas into the Pressure Suppression Tanks in the case of a Loss of Coolant Accident. The steam condensation into a subcooled water pool has been investigated to characterise the condensation regimes occurring during dust deposition tests. The dust distribution on the tank walls strongly depends on the steam jet length and on the effective heat transfer coefficient. Few grams of dust reduce the water transparency, therefore separated tests without dust overcome this drawback. Measurements of the lengths and surfaces of the steam jets (which permit to calculate effective average heat transfer) have been performed by means of image analyses and have been compared with theoretical correlations. The comparison showed a good agreement between the experimental data and theoretical correlations. Useful data have been obtained for implementing numerical models of dust deposition and for understanding the dust distribution on the tank wall obtained in the experimental tests.