Abstract
At the Fukushima Daiichi nuclear power plant accident, the emission of radioactive materials into the atmosphere was caused. SPEEDI was used to assess the dose emitted by this accident, and overestimation and underestimation were seen at the rained or snowed area. In this research, the diffusion prediction model of radioactive materials taking into account the wet deposition was described and the performance of this model was evaluated to improve this overestimation and underestimation. The different methods were used to accomplish this problem of SPEEDI. Atmospheric dynamic model CReSS is adopted to analyze the meteorological condition. Positions of each particle are calculated by the trajectories of many particles. Diffusion by the turbulent flow are calculated by random-walk method. Wet deposition is modeled by the change of number density. Parameters of water substance are based on the value suggested by CReSS. Analysis taking into account the wet deposition was aimed by using methods above mentioned.
