Plume Gamma Dose Evaluation under Non-Homogeneous Non-Stationary Meteorological Conditions using Particle Trajectory Model for Short Term Releases

The particle trajectory model is employed to estimate plume gamma dose due to elevated release (100 m) of 41 Ar under non-homogeneous and non-stationary meteorological conditions using time varying vertical profiles of meteorological parameters given by SODAR. Unit release rate (1 Bq.s -1 ) of 41 Ar was assumed for one hour for the estimation of gamma dose. The gamma dose is also computed using the Gaussian plume model for comparison based on one hour average meteorological data. It is observed that the ground level plume gamma dose derived using the Gaussian plume model is lower by a factor of 4 than that derived using the particle trajectory model for typical unstable conditions. It is higher by two orders of magnitude for the typical stable condition studied here. The present study considers only vertical profiles of meteorological parameters and their variation with time. However, the model is capable of including horizontal variation in meteorological parameters on a three-dimensional computational domain, if such data are available. The internal consistency of the particle trajectory model is verified with the Gaussian plume model under homogeneous and stationary meteorological condition. This study assumes great significance during any unplanned releases of radioactivity into the atmosphere from nuclear power plants.