Heavy liquid-metal pool thermal-hydraulic experiments and simulations

The validation of decay heat removal (DHR) systems and the characterization of thermal hydraulic phenomena in the plena of the liquid metal-cooled, pool-type research reactor MYRRHA, under design at SCK CEN, the Belgian Nuclear Research Centre, is accomplished by experiments and numerical investigations. For this purpose, the E-SCAPE facility at SCK CEN is a thermal hydraulic 1/6-scale 3-D model of the primary system of MYRRHA, with an electrical core simulator, and cooled with Lead Bismuth Eutectic (LBE). Its scaling is based on the preservation of the overall system behavior and the reproduction of the major thermal hydraulic phenomena under DHR conditions. Results from steady-state and transient thermal hydraulic experiments in forced and natural circulation demonstrate that in loss of flow conditions, a natural circulation flow establishes, driven by buoyancy, that can remove the core power, with fuel cladding and reactor structure temperatures that are within safety limits. In natural circulation, thermal stratification occurs in the upper plenum of the facility. System Thermal Hydraulics (STH), Computational Fluid Dynamics (CFD) and coupled STH/CFD models of E-SCAPE have been built in different phases of its lifecycle for scaling, design, pre-test and post-test analyses. The results of post-test simulations are compared with experimental data, showing that the phenomena driving the flow are accurately represented in both the numerical models and the experimental facility.