Development of a Simplified Model for the Passive Containment Cooling System

Abstract

A simplified model for the passive containment cooling system (PCCS) has been developed in a three-dimensional CFD code CYCAS. To evaluate the performance of the PCCS, a transient liquid-film tracking model has been developed and a set of heat and mass transfer models were applied based on the assumption of heat and mass transfer analogy. For the condensation on the inner surface of containment vessel, the condensation rate was computed with the assumption of mass and heat analogy and the effect of non-condensed gas was considered to correct the phase-change rate. In the end, the condensing model and the evaporating model were coupled to establish the complete model for the PCCS. To validate the PCCS model, the condensation model and the film-cooling model were separately validated firstly, which agrees well with the experimental data. In the absence of relative tests, a test case of a small scale AP600 was implemented in the complete PCCS model. The computational results of the film thickness agree well with the COMMIX results at both transient and stable states. Effects of the film cooling on the thermal hydraulics in containment were investigated.