Numerical simulation of purge gas flow characteristics in randomly packed tritium breeder pebble bed

Solid tritium breeder blanket is one of the most important blanket candidates for fusion reactor and fusion-fission hybrid reactor. The purge gas flow characteristics in the channels of pebble bed are important for the effective extraction of bred tritium from the solid breeder materials. A random packed structure of breeder pebbles, generated by Discrete Element Method (DEM), is verified by radial porosity distribution. The flow field parameters of the purge gas in channels are solved by Computational Fluid Dynamics (CFD) solver. The numerical analysis shows the velocity of the purge helium fluctuates with porosity distribution and uniformly increases with increasing inlet velocity, remarkable changes of flow direction and velocity occur in the channels. Blake-Kozeny equation is well applied to predicting the pressure drop in this random packed pebble bed. (authors)