Abstract

The goal of this work is to design a nozzle system around the Reactor Pressure Vessel (RPV) of a VVER-1000 nuclear reactor which would ensure successful melt retention during a severe accident. Simulations were performed with a multiphase model in ANSYS Fluent 19.1 to determine this. The results suggest that an efficient cooling can be achieved by inducing a flow rising parallel to the RPV walls in the flooded reactor cavity. In order to do this, it is proposed to use one central nozzle below the RPV and a ring of 32 nozzles 0.5 m above the RPV bottom. Assuming a 2 bar pressure, injection of 750 m³/h water at 80^oC through the nozzles led to little steam production and a heat flux below the critical value.