SAMPO-P Test Facility and Numerical Pretest

Abstract The in-vessel retention (IVR) strategy was developed to retain the corium within the reactor pressure vessel (RPV) to prevent the release of radioactive products during severe accidents. However, the RASPLAV study reveals the potential formation of a two-layer melt pool pattern, wherein the heat flux in the top metal layer significantly exceeds the average heat flux density, posing a considerable threat to the integrity of the pressure vessel and the success of the IVR strategy. Previous studies on stratified melt pools have primarily concentrated on the natural convection behavior within the melt pool using scaled facilities. To better understand the thermal behavior of the two-layer melt pool heat transfer, this study constructed a 1:1 ratio-sized 2D stratified melt pool experiment facility ‘SAMPO-P’ based on the HPR1000 RPV lower head. The numerical pre-test simulations are conducted using in-house code to help determine the experimental conditions and test matrix. The simulants of the oxide layer and metal layer were Chlorine salt and Al-Mg alloy. The results indicate that as the heating power increases from 180 kW to 255 kW, the temperature and heat flux increase while the thickness of the bottom crust decreases with no significant heat flux peak in the metal layer observed. The first experiment is scheduled for this year. The experimental results are expected to provide essential insights into understanding the flow and heat transfer characteristics and further improve the numerical model in future research.