Simulation of a Nuclear Fallout Scenario in the Zaporizhzhia Nuclear Power Plant During the Ukraine Conflict: Implications of Dose Rate Distributions for Downwind Populations

Introduction Russia's full-scale attack on Ukraine and direct targeting of power infrastructure underscores a heightened risk for nuclear reactors. This study explores the potential of a radiological release at the Zaporizhzhia Nuclear Power Plant amid the ongoing large-scale combat operations (LSCO), using dispersion modeling to estimate and discuss the impact on health security across the NATO alliance. Materials and Methods The developed scenario uses the FLEXPART dispersion model to simulate the release and resultant ¹³⁷Cs surface concentration. The values serve to estimate effective radiation dose and absorbed thyroid dose over 1 year and three age groups. Results are compared to public protection guidelines. Results It is determined that in this scenario, only the most contaminated 1-2 km² next to the source would require evacuation, although populations up to 50 km away from the source should follow food consumption restrictions and iodine thyroid blocking measures, especially for young children. Discussion This study underlines the importance of immediate informing of affected populations, especially considering the war and rurality in Ukraine, as well as preparedness regarding foodstuff restrictions and availability of iodine thyroid blocking tablets. Reducing assumptions regarding dose estimation and the dispersion simulation input parameters forms a clear avenue for further research to provide a more comprehensive risk analysis. Conclusion This study models radionuclide surface concentration and subsequent radiation dose estimates, following a hypothetical radiological release at the Zaporizhzhia Nuclear Power Plant. Localized evacuation, immediate and clear informing of the population, paired with food consumption restrictions and iodine thyroid blocking measures in the close vicinity of the release, seem to be the most likely and critical actions to follow. These insights are valuable for the authorities in charge of disaster preparedness, response, and medical planning in Ukraine and neighboring NATO countries. Further work is needed to account for variability in meteorology and release terms.