Three Dimensional Numerical Simulation of Atmospheric Dispersion Influenced by Complex Underlying Surface Surrounding Nuclear Power Plant

An accurate simulation of radioactive plume dispersion in a geometrically complex plant region is a prerequisite in emergency preparedness for regulators to design effective policies. The influences of typical complex underlying surface in inland nuclear power plants, such as huge cooling towers, on the atmospheric dispersion have been simulated by commercial Computational Fluid Dynamics (CFD) software and compared with wind tunnel tests by Statistical performance measures under four fixed wind directions considering the relation between dominant wind directions and main structures. The simulation results show that, the influences of cooling towers on local wind field are closely related to the relative position of the release source and the building groups. The mechanical disturbance of cooling towers increased the turbulence intensity significantly, leading to the distribution expansion of pollutants; while the wake zone changed the vertical movement, leading to the increase in the ground concentration near release point and the decrease in distance of maximum ground concentration from release point. The objective of this study was to simulate the wake structure and its effects on mean flow and turbulence of the atmospheric boundary layer (ABL) under the action of the mechanical disturbance with the combination of the terrain and the buildings for given key wind directions, and to analyze the flow characteristics around the building groups and to provide a visual quantitative analysis method for the transport and dispersion of near field in the inland nuclear power plant.