Simulation of atmospheric dispersion and dose assessment by a coupled WRF-HYSPLIT model for Bushehr power plant

The simulation and prediction of pollutants dispersion entering into the atmosphere (such as material releases from the chimneys of industries and power plants) are important in different views, long-term environmental monitoring and dose calculations as well as issuing an appropriate warning in the event of an accident. To this end, a system of coupled meteorology-dispersion model can be used. In fact, a numerical weather prediction model is coupled to a dispersion model. In the present work, the weather research and forecasting (WRF) model is used to provide the meteorological data for the HYSPLIT (HYbrid Single Particle Lagrangian Integrated Trajectory) dispersion model.
Sensitivity and validation of the WRF model are conducted by utilizing different combinations of physical parameterization schemes (microphysics, longwave radiation, shortwave radiation, surface layer, land surface, boundary layer and cumulus convection) for the prediction of meteorological parameters in an area containing the Bushehr power plant. For this purpose, eight different configurations are used. Then, for several dates, sensitivity, and validation of the model results is carried out to find the proper configuration of the model. Assessment of the predictions of the WRF model is carried out by computing the statistical parameters including correlation coefficient (CC), root mean square error (RMSE), and comparing with the collected observational data (on-site the meteorological tower and Sodar system in Bushehr power plant and synoptic meteorological stations nearby).
After determining the proper configuration of the WRF model, dispersion simulations and annual effective dose for the adult age group are carried out by WRF-HYSPLIT coupled model under normal conditions for Bushehr power plant. The predicted annual effective dose for the adult age group by the coupled model for the years 2014, 2015 and 2016, provided 5.8×10-8 (Sv), 6.7×10-8 (Sv) and 1.1×10-7 (Sv) respectively, in return value 7.7×10-8 (Sv) for Bushehr power plant final safety analysis report (FSAR report). Comparing these results show that the simulation and prediction of dose by the coupled WRF-HYSPLIT model are in good agreement with observations and indicates the validity of the simulations. The ratio of predicted annual effective dose to dose limit for normal operation is obtained less than 0.2 percent (The results of the present work showed that the coupled WRF-HYSPLIT model can be used as a promising tool for the prediction of dispersion and dose calculations for Bushehr power plant under normal operation. In addition, the results of this coupled model can provide the required information for emergency management to forecast the movement and direction of radioactive plume and exposure dose calculations.