Dispersion, radiological dose assessment, risk evaluation, and emergency response of radioactive materials based on WRF-HYSPLIT modeling.

Accurate prediction of radionuclide dispersion is essential for radiation hazard prevention, yet predictive studies remain limited. This study employed the weather research and forecasting (WRF) model to generate a high-resolution meteorological data for the hybrid single particle lagrangian integrated trajectory (HYSPLIT) model to simulate the atmospheric transport of iodine-131 (131I). The calculation results of the real-time impact of radioactive emissions were obtained by first solving the gridded standard response distribution, then multiplying the coefficients according to the actual emission situation. Results revealed that the diffusion range of the nuclide 131I in the horizontal direction increased rapidly with the increase of altitude. Horizontal diffusion peaked at 1500 m altitude and declined above 2000 m, while vertical transport reached 1000 m within 2 h and 2000 m by 8 h, with effects lasting over 720 h. Deposition peaked 8 h post-release, particularly between 100 and 1000 m. Integrated dose assessment across multiple exposure pathways (e.g., dry/wet deposition and inhalation) showed negligible differences between adults and children, supporting unified evacuation planning. This study also revealed the potential threats to human health posed by various radiation dose pathways, such as environmental immersion external exposure, dry deposition, wet deposition external exposure, and internal exposure. Emergency response zones and timeframes were defined using international atomic energy agency (IAEA) standards. Though focused on 131I, the approach applies to other fission products. In addition, by combining field monitoring data and remote sensing technology to verify and optimize the simulation results, not only can the impact be calculated quickly after a real nuclear accident, but also the impact can be predicted rapidly after a hypothetical accident, which significantly improve the reliability and practicality of the emergency response plan.