MICRO-METEOROLOGICAL DISPERSION PARAMETRISATION FOR SHORT RANGE RADIOACTIVE CONTAMINATION MODELLING IN THE ANGRA DOS REIS NUCLEAR POWER PLANT SITE

In the present work we use an Eulerian diffusion approach as the base for a micro-meteorological dispersion parametrisation for short range radioactive contamination modelling in the An- gra dos Reis nuclear power plant site. The closure of the diffusion equation is implemented by means of eddy diffusivity (K-theory). The parametrisations for the eddy diffusivity co- efficients are determined from micro-meteorological parameters that were extracted from meso-scale Weather Research and Forecasting (WRF) simulations. The model is based on Taylors statistical theory together with a model for Eulerian turbulence spectra from a su- perposition of a buoyant and a shear contribution. We implement an interface between a LES model for the planetary boundary layer and orography related features of WRF and simulate four days, from February, the 1st to the 4th of 2010, for the environment around the nuclear power plant site at Angra dos Reis, Rio de Janeiro state, Brazil. After extraction of micro-meteorological data we determined the eddy diffusivities under the hypothesis of homogeneous turbulence. As the principal result we show the time dependence (for the time scale of a day) of the dimensionless vertical eddy diffusivity coefficients.