BORA4-PTS: Experimental reproduction of a Pressurized Thermal Shock, and building of numerical simulation with the CATHARE Code

When a break occurs in a nuclear reactor, a fast cooldown has to be down to prevent the melting of the core. This is done by the injection of cold water at 7 °C, in a pressurized vessel at 295 °C. This is a Pressurized Thermal Shock. To improve the safety of the nuclear reactor, an experimental facility was built to analyze the mix of hot and cold water in the downcomer of the vessel. This is the BORA4-PTS experiment. Salt water at 45 °C is injected into stagnant pure water at 20 °C, to represent the injection of cold water in hot water. Through this experiment, a scaling was establish to compare it with the reactor case. We then made a numerical simulation of this experimental facility with the CATHARE code. With this simulation come another scaling, in order to properly compare the numerical and the experimental results. The numerical simulations give results that are very similar to the experimental ones. With this experiment, we show the excellent capacity of CATHARE to simulate and model the complex thermohydraulic inside a downcomer.