A Numerical Study of Particle Deposition Through Fuel Pebble Bed in HTGR

Abstract

The study on the deposition of graphite dust is significant to the safety of High-Temperature Gas-cooled Reactor (HTGR) due to potential accident such as localized hot-spots and intensity change which is caused by the graphite dust generated by abrasion of fuel elements. Based on the steady flow and three-dimensional face centered structures of fuel pebble bed, the discrete phase model (DPM) were applied to simulate trajectory of graphite dust in conditions of HTGR. To determinate the deposition of particle, the present study introduces a rebound condition with critical velocity by a user defined function. The particle trajectories show most of particle deposition can be summed up as the effect of backflow region, turbulent diffusion and inertial impact. The original trap condition overestimates the deposition fraction especially for large particles compared with involving rebound condition. In addition, the trend of deposition fraction shows as the dimeter of particle increases, deposition fraction decreases first and then increases.