Preliminary study on atmospheric dispersion modeling of Cesium-137 radioactive incident at KIM Cikande, Indonesia: General analysis.

The discovery of a Cesium-137 (Cs-137) radioactive source in the Modern Industrial Estate (KIM) Cikande, Indonesia, in 2025 highlighted the need to evaluate the potential atmospheric dispersion of radionuclides in industrial areas. This study aimed to investigate the influence of different meteorological datasets on the atmospheric dispersion of Cs-137 using the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model. A descriptive-comparative numerical simulation approach was employed using three meteorological datasets with different spatial resolutions: the Global Data Assimilation System (GDAS) 1°, GDAS 0.5°, and the Global Forecast System (GFS) 0.25°. The simulation outputs were evaluated based on plume direction, concentration distribution, affected area, hotspot identification, and peak concentration. The results showed that Cs-137 concentrations were highest near the release source and gradually decreased with increasing distance because of advection, turbulent diffusion, and atmospheric dilution. Higher-resolution meteorological datasets produced more detailed plume structures and improved hotspot identification, with GFS 0.25° producing the most spatially detailed plume representation among the datasets evaluated. However, the relative accuracy of the datasets could not be determined because independent meteorological and radiological observations were unavailable for validation for regional-scale assessments. Future studies should incorporate measured source-term data, field monitoring, and effective dose assessments to improve model validation and support more comprehensive radiological risk analyses and emergency preparedness planning.