Numerical study of aerosol dispersion following the chemical explosion of plutonium-containing explosives under different wind speeds

The regional atmospheric dispersion of radioactive smoke clouds generated by chemical explosions presents significant radiological hazards, necessitating accurate predictive modeling for effective emergency response and risk mitigation. This study utilizes an integrated large eddy simulation (LES) framework enhanced with density-gradient-based adaptive mesh refinement (AMR) to resolve diffusion flow fields, coupled with a discrete phase model (DPM) to investigate the multiscale transport behavior of plutonium aerosols within explosion plumes., This simulation framework addresses key limitations in existing models related to turbulent diffusion, particle inertia, and variability in wind fields. Validation against experimental data from the Green Field (GF) study demonstrates strong agreement with observed plume rise dynamics, achieving an error range of less than ±0.5 m (p > 0.05) during late-phase dispersion. Key findings indicate that particle size is a dominant factor influencing diffusion efficiency, with smaller particles (<2 μm) exhibiting a 30% greater radial displacement compared to larger particles (12 μm) under identical flow conditions. The temporal evolution of velocity distributions reveals a systematic transition from high-energy, turbulent dispersion (mean velocity of 3.7 m/s at 2.5 s) to quiescent settling (mean velocity of 0.80 m/s at 50 s), quantifying a tenfold decrease in kinetic energy due to turbulent dissipation and gravitational work. Additionally, wind-speed modulation significantly enhances horizontal dispersion asymmetry, with wind speeds of 4 m/s resulting in double the lateral cloud expansion compared to stagnant conditions. This study provides a predictive framework for optimizing emergency protocols and improving global preparedness for radiological threats, offering critical insights into aerosol inertial-turbulent transitions, buoyancy-driven transport, and long-range deposition dynamics.