Abstract: A wind tunnel experimental study was performed in small scale for representative nuclear power plant site. The influence of buildings and terrain to radioactive material diffusion in the near field was studied. The model rate is 1∶600, and the similar demand of model and physical prototype is satisfied by correcting profile of wind and turbulence. 6 wind directions were studied for disturbing of building and terrain to horizontal and vertical flow field under condition of the annual average wind speed and light wind speed. The experimental results show that the wind speed is deficit and turbulence intensity is improved in WNW to ESE axis wind direction. The different sample sites have different impact to wind speed and turbulence intensity. The distribution of stack emission and ground-level emission in ground axis were different in the condition of annual mean wind speed and light wind speed. The axial maximum diffusion factor is 4.05×10^-5 s/m³ under stack emission condition, and the distance presented is 240 m. The axial maximum diffusion factor is 4.79×10^-3 s/m³ under ground emission condition, and the distance presented is 45 m.

Key words: wind tunnel experiment, small scale, buildings, light wind condition