Visualization of two-phase flow through a packed bed of spheres in a circular pipe

Ito, Daisuke*; Rivera, M. N.*; Ito, Kei*; Saito, Yasushi*; Aoyagi, Mitsuhiro ; Matsuba, Kenichi  ; Kamiyama, Kenji  

Two-phase flow through porous media is an important phenomenon to develop a severe accident analysis code for nuclear reactors. When a core disruptive accident occurs in sodium-cooled fast reactor, the fuel inside the core become melted and interacts with the coolant. As a result, gas-liquid two-phase flow will be formed in the debris bed, which may have porous nature depending on the cooling process. Thus, the present work focuses on the two-phase flow structure in different porous media conditions (porous size, liquid and gas flow velocity). In this study, X-ray radiography, which is very helpful to understand the two-phase structure inside the porous media, was applied to measure porosity and void fraction distribution in the packed bed of spheres.