Porous Media Applied To Pebble Bed Modular Reactor Thermal-hydraulics

Résumé: Among the SMRs (Small and Medium sized Reactors) for electricity generation currently under development we find the PBMRs (Pebble Bed Modular Reactors). These nuclear reactors work at very high temperature and are cooled generally by helium flowing through spherical fuel pebbles. In this work we focus on the thermal hydraulic differences when using air or helium as a cooling fluid. The porous media model can be used for PBMR thermal-hydraulic studies. A mathematical model is developed thanks to the conservation equation of mass, momentum and energy. The model is made for a two-dimensional permanent flow regime in an annular cylindrical geometry filled with a porous media saturated by a single fluid phase. The convective heat transfer is evaluated for different ratios of internal and external radius and for different Biot numbers, for both air and helium. The results show that helium still the best cooling fluid. Air can ensure the transfer of less than 40% of the heat generated in the nuclear reactor core. In some particular situations: as cooling accidents or when removing the residual heat, air can then play a significant role.

Publié dans la revue: Journal of Scientific Research