Method for solving atmospheric dispersion parameters of radioactive aerosols based on wind-tunnel laser measurement experiments

Abstract

Certain fraction of radionuclides was inevitably discharged into the atmosphere during the normal operation of nuclear power plants. Therefore, the atmospheric dispersion of these airborne radioactive aerosols is an essential part of radiation environmental assessment during the siting, construction, and operation of nuclear power plants. Gaussian plume model is the most widely used method for this assessment. Evaluation uncertainty of this method mainly depends on the selection of atmospheric dispersion parameters. In this paper, the laser measurement method was carried out in the atmospheric wind-tunnel dispersion experiments of aerosols, and a method for solving atmospheric dispersion parameters based on high-resolution laser scattering images of plumes was proposed. Firstly, a full-frame statistical image of aerosol atmospheric plume trajectories was obtained through high-resolution laser measurement. Secondly, image processing was performed to remove noise, then to acquire light intensity of image pixels, and to make 95.45% (2σ) of the total light intensity fall within the plume trajectory to determine the plume boundary line at last. Finally, the atmospheric dispersion parameters were determined by optimal fitting, using the Gaussian plume model as a benchmark. Compared with the commonly used method for solving atmospheric dispersion parameters based on single-point densitometer detection experiments, the method based on laser measurement proposed in this work has advantages in reflecting directly realistic plume trajectory of both aerosols and particles with large sizes. This study can provide technical support for the accurate evaluation of aerosols or particles atmospheric dispersion.