Numerical simulation of flow with volume condensation in a model containment

Abstract

One severe accident scenario is a leak in the primary circuit of a PressurizedWater Reactor (PWR) resulting in steam injection into the containment. In this case, wall and volume condensation can occur in the containment. The condensation phenomena are of interest for safety considerations. This paper presents a newly developed volume condensation model with a two-phase flow for the ANSYS CFX code. A two-fluid model with a continuous gas phase consisting of a steam-air mixture and a dispersed liquid phase composed of water droplets in thermal and mechanical non-equilibrium is applied, so that both phases are modeled with separate temperatures and velocities. The motion of the droplet due to gravitational force is considered. Volume condensation is modeled as a sink of mass and source of energy at the droplet interfaces. In order to focus on the volume condensation, the new model is applied to a simple two-dimensional steady state test case. The volume condensation model is validated with a condensation experiment TH2, which was performed in the German THAI facility.