Evaluation and Sensitivity Study of Uniform Kernel Method in Atmospheric 41Ar Dispersion Against the Belgian Field Experiment

Abstract The Uniform kernel is an effective kernel density estimator used in the Lagrangian Particle Dispersion Model (LPDM), estimating the dispersion trajectory of radionuclides, and determining radioactive concentration to assess environmental contamination levels. This method significantly decreases computational resources compared to the traditional box counting concentration calculation in LPDM, serving as a fast and accurate tool to ensure effective nuclear emergency response in the early stages. In this paper, the effectiveness of the Uniform kernel is evaluated systematically via the measurements from eight gamma dose rate monitoring sites deployed at the Belgian field experiment by coupling the California Meteorological Model (CALMET) and the Lagrangian Particle Model (LAPMOD). Sensitivity studies are performed on three important parameters, including bandwidths multiplication factors, horizontal grid size, and particle numbers. The results demonstrate satisfactory agreement between simulations and measurements, with acceptable statistical metrics. The sensitivity analysis highlights the significant impact of bandwidths multiplication factors on the Uniform kernel, summarizing appropriate parameters for applying the Uniform kernel in small-scale dispersion for the nuclear power plant scenarios.