Atmospheric Dispersion Patterns of Radionuclides Originating from Nuclear Power Plant Accidents under Various Release Types

Abstract

Nuclear power has begun to lose its popularity after the major catastrophes of Chernobyl and Fukushima that caused a global environmental and public health problem. Radioactivity released from these accidents spread all around the world and negatively influenced large areas as a result of different meteorological conditions prevailing at the time of the accidents. Another particularly important parameter used in assessing the atmospheric dispersion of radioactivity is the characteristics of the source term that defines the release pattern of radionuclides from the accident site. Core inventory and shape and extent of the release define the source term to be used in simulating the dispersion pattern of radioactivity. Thus, mathematical representation of the source term is a crucial part of the dispersion modeling of radionuclides. Ideal types of releases (such as pulse, step, linear, sinusoidal) can occur in an accident or a combination of these types can constitute the real pattern of the release from the accident’s source. The mathematical character of the release is influential in the overall dispersion and deposition of radioactivity. Based on this premise, this study is conducted to assess the possible differences in the spatial distribution of dispersed and deposited radionuclides that can originate from a potential accident in Akkuyu nuclear power plant (NPP) in the southern Mediterranean coast of Turkey. Simulations are performed with FLEXPART model to predict the atmospheric dispersion and ground level depositions of radionuclides to be released from a hypothetical accident in Akkuyu under various release patterns and different meteorological conditions representing extreme conditions. Model simulations considered a 10-day release duration with distinct release patterns under extreme meteorological conditions for the site. A comparative assessment is then conducted to evaluate the extent and magnitude of Cs-137 dispersion and deposition, which is the most commonly used radionuclide in NPP accident simulations.