Numerical analysis of liquid fall type gas entrainment in pool-type fast reactor

摘要

Argon covering the free surface of the pool-type sodium-cooled fast reactor may be mixed into the coolant in form of entrainment bubbles due to the fluctuation of liquid surface, which introduces positive reactivity to the core, reduces the heat exchange capacity of the core and intermediate heat exchangers (IHXs), and possibly leads to the cavitation of the primary sodium pump (PSP), threatening the safe operation of the reactor. In this study, the computational fluid dynamics (CFD) simulation of liquid sodium fall entrained argon was carried out based on the Volume of Fluid (VOF) interface tracking method to describe the entrainment process in detail, and the influences of geometry size, initial liquid level height and inlet velocity on entrainment were analyzed successively. It was found that the re-submergence velocity, having a linear relation with the re-submergence angle, is the key factor of the liquid fall type gas entrainment. It can be used to judge whether the liquid fall type entrainment occurs conservatively. In addition, the parameters affecting the re-submergence velocity are specifically analyzed from the supplementary cases, according to the results of which, the empirical relation of the re-submergence velocity is obtained. Therefore, the situation of liquid fall type gas entrainment under various working conditions can be predicted numerically. (C) 2021 Elsevier Ltd. All rights reserved.