Aplicacao da fluidodinamica computacional a dispersao atmosferica de radionuclideos na vizinhanca de uma central
Most studies of atmospheric dispersion of radionuclides released from Nuclear Power Plants (NPPs) are based on Gaussian plume models or on the use of a convection diffusion equation. Such models are inexpensive and can be useful in the atmospheric Mesoscale, of the order of 2 2000 km from the NPP. However, they fail to take into account the turbulence generated by the interaction of the wind with buildings, the terrain, and with the convective forces of the released material stream, which are the dominant factors in the local scale, of the order of 0 2 km from the source of emission. This thesis presents a Computational Fluid Dynamics (CFD) approach to the atmospheric dispersion of radionuclides in the close vicinity of NPPs. Large Eddy Simulation based on the Navier Stokes equations, dynamic adaptive finite element meshes, and parallel computing techniques, are combined in a computer code designed to take into account the effect of the locally generated turbulence on the dispersion of the released radioactive material. The results obtained, although preliminary, are encouraging and show the potential of CFD tools to address this important safety assessment problem.