A complete CFD study on natural convection in the TRIGA Mark II reactor

This work describes the most complete and up-to-date thermal-hydraulics CFD model for studying the natural circulation regime within the entire TRIGA Mark II reactor at the University of Pavia. Building on preliminary works, this paper tackles the treatment and investigation of natural circulation in the reactor core and pool, highlighting the coupling between the two components. Despite the assumptions behind the model – such as the use of an unsteady RANS turbulence model and the treatment of the supporting grids as a porous media – the validation compared to experimental data shows quite a good agreement. The model is thus accurate enough to describe the natural convection regime within the core and the pool and highlight local phenomena, such as localised sub-cooled boiling and recirculation.