Evaluating local wind circulation metrics for radionuclide transport and dispersion: A practical approach for radiological safety

Abstract

Understanding the atmospheric dispersion and transport of radioactive materials is crucial for assessing radiological exposure and potential health risks, as well as for optimizing radiological environmental impact assessment and radiological monitoring networks. The dispersion of radionuclides following an accidental release from a nuclear facility is highly influenced by local wind circulation patterns, yet these effects are often overlooked in routine atmospheric dispersion assessments. This study evaluates the role of simple wind circulation indices—stagnation, recirculation, and ventilation—in shaping the dispersion of radioactive material, demonstrating their relevance for nuclear safety planning. The analysis focuses on the Almaraz Nuclear Power Plant (ANPP), where 1.256 atmospheric dispersion simulations were conducted using the RIMPUFF model over a four-year period (2012–2015) under different meteorological conditions. Considering the existing set of 84 monitoring stations included in the EURDEP system in an area of 200 km around the ANPP, the influence of each local atmospheric process is analyzed and characterized by taking the TGDR maximum values reached, and the number of monitoring stations affected in each simulation. On average, results demonstrate that high stagnation confines radionuclide plumes near the source, with maximum TGDR reaching 0.005 μSv/h and affecting up to 14 monitoring stations. In contrast, high recirculation enhances local accumulation, leading to, on average, peaks of 0.035 μSv/h and reducing the number of stations impacted (12 monitoring stations). High ventilation conditions promote wider dispersion, with maximum TGDR of 0.002 μSv/h affecting 10 monitoring stations. Extreme cases of each atmospheric process are also analyzed, showing distinct effects on the spatial distribution of affected monitoring stations. These findings highlight that wind circulation indices, derived from routine meteorological data, offer a straightforward yet effective means of anticipating dispersion behaviour in emergency scenarios.