Gas Ingress during Side Vessel Break: Experiments and Numerical Simulations with a Simplified Pool-type Scaled Water Model

In the safety analysis of a pool-type liquid metal cooled reactor, the scenario of a large break of the reactor vessel is evaluated. Among the different possibilities the fall of the full bottom of the reactor vessel is analyzed as a bounding case for possible ingress of gas. It is analysed whether gas from the surroundings might enter the system and, more specifically, enter the core. The presence of gas would interrupt the cooling of the core region. A water model has been designed and studied both experimentally and numerically in several conditions, to evaluate the amount of gas entering from the side break of the vessel, taking into account different falling heights of the bottom of the vessel and to validate the ability of CFD to correctly reproduce the phenomena observed. The experimental data obtained with water with the simplified configuration were compared with a predictions by a CFD model with a 2D-axisymmetric domain. This confirmed the ability of CFD model to correctly predict the phenomena.