Abstract: Resuspension of radioactively contaminated soil particles represents one of the key environmental release pathways and critical source terms in radiological environmental safety assessment. This study employs a bidirectional DEM-CFD coupling approach to perform microscopic analysis of the incipient motion process of 10 μm ordinary dust particles (SiO₂) and typical radioactive particles (U₃O₈ and PuO₂) on rough particle bed surfaces. The results reveal that the geometric morphology of densely packed rough beds exerts a significant influence on boundary layer flow; compared to an ideal smooth wall, the rough bed markedly displaces the boundary layer structure upward and increases the near-wall vertical velocity component. Particle resuspension initiation emerges as a complex spatiotemporal evolutionary process involving in-situ micro-vibration, rolling ascent, and eventual detachment. Simulation results indicate that the critical threshold wind speed for ordinary dust is 1.60 m/s, whereas for the typical radioactive particles U₃O₈ and PuO₂ it rises to 2.05 m/s and 2.21 m/s, respectively—an increase of approximately 28% and 38% respectively. This clearly demonstrates the synergistic inhibitory effect of enhanced gravity and stronger surface adhesion resulting from the higher density imparted by radioactive nuclides. The present work provides microscopic mechanistic insight and more accurate threshold references for parameterizing radioactive particle resuspension and for environmental risk assessment models at contaminated sites.

Key words: radioactive contamination, particle resuspension, discrete element method, computational fluid dynamics