Large-eddy simulation of turbulent winds during the Fukushima Daiichi Nuclear Power Plant accident by coupling with a meso-scale meteorological simulation model

摘要

A significant amount of radioactive material was accidentally dischargedinto the atmosphere from the Fukushima Dai-ichi Nuclear Power Plant from12 March 2011, which produced high contaminated areas over a wide region inJapan. In conducting regional-scale atmospheric dispersion simulations, thecomputer-based nuclear emergency response system WSPEEDI-II developed byJapan Atomic Energy Agency was used. Because this system is driven by ameso-scale meteorological (MM) model, it is difficult to reproducesmall-scale wind fluctuations due to the effects of local terrainvariability and buildings within a nuclear facility that are not explicitlyrepresented in MM models. In this study, we propose a computational approachto couple an LES-based CFD model with a MM model for detailed simulations ofturbulent winds with buoyancy effects under real meteorological conditionsusing turbulent inflow technique. Compared to the simple measurement data,especially, the 10 min averaged wind directions of the LES differ by morethan 30 degrees during some period of time. However, distribution patternsof wind speeds, directions, and potential temperature are similar to the MMdata. This implies that our coupling technique has potential performance toprovide detailed data on contaminated area in the nuclear accidents.