Assessment of Radiological Dispersal Devices in Densely Populated Areas: Simulation and Emergency Response Planning

The increasing threat of terrorism involving Radiological Dispersal Devices (RDDs) necessitates comprehensive evaluation and preparedness strategies, especially in densely populated public areas. This study aims to assess the potential consequences of RDD detonation, focusing on the effective doses received by individuals and the ground deposition of radioactive materials in a hypothetical urban environment. Utilizing the HotSpot code, simulations were performed to model the dispersion patterns of 137Cs and 241Am under varying meteorological conditions, mirroring the complexities of real-world scenarios as outlined in recent literature. The results demonstrate that 137Cs dispersal produces a wider contamination footprint, with effective doses exceeding the public exposure limit of 1 mSv at distances up to 1 km, necessitating broad protective actions. In contrast, 241Am generates higher localized contamination, with deposition levels surpassing cleanup thresholds near the release point, creating long-term remediation challenges. Dose estimates for first responders highlight the importance of adhering to operational dose limits, with scenarios approaching 100 mSv under urgent rescue conditions. Overall, the findings underscore the need for rapid dose assessment, early shelter-in-place orders, and targeted decontamination to reduce population exposure. These insights provide actionable guidance for emergency planners and first responders, enhancing preparedness protocols for RDD incidents in major urban centers.