CFD methodology and validation for IVR-ERVC under severe conditions

ERVC (External Reactor Vessel Cooling) strategy is proposed to be adopted as a key issue of IVR (In-Vessel Retention) which is applied in AP1000, VVER-640 and APR1400 as an important method to avoid the consequences of severe accidents. Most researches concerned about the CHF of ERVC are based on experiments of which the scale is large and costly and only afforded by national research institutions. Recent days, some people use thermal-hydraulic cods to deal with CHF of ERVC, which cannot obtain physical mechanisms leading to the CHF. So this paper is dedicated to explore a way with CFD method to solve where CHF happens and predict the value. The framework for simulations is the commercial CFD code CFX. And Eulerian multiphase CFD models are developed to resolve wall boiling and CHF. The numerical results for CHF of ERVC are validated against existing experimental data in this paper. With the CFD simulations, the physical mechanism of CHF occurring in experiments of ERVC is to be discussed. (author)