Aerosol behavior in two-phase flow during a pool scrubbing

Abstract

As in clear from Fukushima Daiichi nuclear disaster, it is expected that the removal effect of Fission Products (FP) by the scrubbing effect in the pool water in the process of BWR containment vessel. In the PWR plants, we should eliminate the steam including fission products with gas by using the pool scrubbing effect, for the case that an accident occurs in the heat-transfer-tube of steam generator. The gas in the containment vessel and primary system including the FP aerosol spread into the pool water, the aerosol in the gas is scavenged in the scrubbing water. We predict the reduction of aerosol which shifts to containment space by the aerosol removal effect of the scrubbing. Hence, the aerosol removal by the pool scrubbing is important to evaluate the source term. In terms of the scrubbing effect for describing the real phenomena, in addition to boiling under reduced pressure conditions of the pool water, in the range that non-condensable gas flowing into the pool water is suitable, the two-phase flow behavior and aerosol behavior are required to elucidate the detailed correlation. This study experimentally examines the relationship between aerosol behavior and bubbles. We obtain the basic data for evaluating quantitatively the effect of removing the nuclear product. Based on these results, we improve the model for the validity confirmation of the severe accidents predictive code such as the MELCOR under the present conditions. We thereby visualize on a rising motion of single air bubble including the aerosol visualization. In this draft paper, we conducted preliminary experiments focused on behavior of single air bubble and bubbles including aerosol. After that we confirmed problems about design of experiment and have devised experimental apparatus systems.