A Gaussian Trajectory Model for Hazard Evaluation for Prolonged Releases from Nuclear Reactors

A model for mesoscale hazard evaluation, along a trajectory, with time/distance varying meteorological conditions, has been developed. For release periods longer than one hour, multiple superimposed trajectories and meteorological conditions are utilized.The centreline concentration for each hour’s release is assumed to move along a trajectory, calculated from actual wind measurements or climatological average data, The model utilizes the Gaussian distribution formulae for the calculation of the concentration at preselected grid points near the ground. The wind speed and stability category may vary continuously along the trajectory, At these grid points the instantaneous (one hour average) and the total integrated concentrations are calculated. Ground deposition is calculated assuming a constant settling velocity.The final results are given as radiation fields and total integrated doses, computed by the methods suggested by WASH-1400 and the ICRP-26 report.Three experiments are presented in the work and the main advantages of the present method for the chosen cases are discussed.