Experimental research on pool scrubbing of particles of radioactive materials

Tests at three different scales were conducted in order to understand the mechanisms of pool scrubbing under a wide range of two-phase fluid dynamic conditions with a special focus on rapid depressurization caused by venting. In the small-scale separate effect test, high resolution two-phase flow measurement techniques utilizing equipment such as a high-speed digital camera, wire mesh sensor and PIV were applied to capture the behaviors of a single bubble（deformation, rising velocity and aerosol tracks）and the evolution of two-phase flow structures（bubble globule breakup, bubble sizes, bubble shapes and swarm rising）. In the large-scale integral effect test, the dependence of the aerosol removal efficiency on submergence and pool temperature was measured under constant pressure and depressurized conditions. Attention was also paid to aerosol materials with different particle size distributions, hydrophilicity and solubility from the viewpoint of their importance for aerosol removal efficiency. To clarify relationships between individual phenomena and combined phenomena observed in two tests, the mid-scale integral effect test was undertaken. In this paper, we overviewed existing analytical models of pool scrubbing, their deficiencies to be improved, the purpose of this experimental project, an outline of experimental approaches and findings obtained so far. © 2020 Atomic Energy Society of Japan, All Rights Reserved.