Development of local-scale high-resolution atmospheric dispersion model using large-eddy simulationpart 6: introduction of detailed dose calculation method. Issue 9 (2nd September 2021) - Nakayama, Hiromasa
ABSTRACT: We developed a LOcal-scale High-resolution atmospheric DIspersion Model using Large-Eddy Simulation (LOHDIM-LES) for the safety assessment of nuclear facilities and emergency responses to accidental or deliberate releases of radioactive materials. In parts 1–5 of this series, the basic performance was examined by comparing with wind tunnel or field experimental results on plume dispersion over various complex surface geometries under ideal and realistic atmospheric conditions. In this study, we introduced a dose calculation method that can simulate air dose rate distributions by considering shielding effects and inhomogeneous distribution of radioactive materials in the air and on the ground and building surfaces. First, we conducted LESs of radioactive plume dispersion and dry deposition in building array and investigated the basic performance of the dose calculation method by comparison with that of Monte-Carlo based three-dimensional radiation transport simulations by Particle and Heavy-Ion Transport code System (PHITS). Then, we compared the LOHDIM-LES results with actual air dose rate obtained from the monitoring posts in a nuclear facility. The observed data were reasonably simulated. Thus, we completed LOHDIM-LES, which can simulate plume dispersion, dry deposition, and air dose rates from complex distributions of radionuclides considering the influence of individual buildings under realistic meteorological conditions.