LAUSR

Abstract Aiming at the dispersion of 131I in the regional scale, this paper proposes a dispersion trajectory simulation method for 131I based on the fully coupled online model of the Weather Research and Forecasting-Chemistry (WRF-Chem). The dry deposition, wet deposition and radioactive decay of 131I have been considered in the Eulerian advection-diffusion equation, which is the three important removal processes of 131I in the atmosphere. The atmospheric dispersion of 131I at the early stage in the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident (March 12th to 17th) was used to simulate to validate the method. Comparison between the 131I concentration of WRF-Chem modeling and the available observations data shows that the dispersion trajectory of 131I at the regional scale was simulated authentically by this method, which can explain the arrival and duration time of the measurements, indicating that the method can be used significantly as a decision support tool for the early nuclear emergency and evaluate the consequences of the accident.