Used The Random-walk Particle-puff Model In Nuclear Accident

Nuclear energy is the unique new energy source that can take the place of fossil fuels onlarge scale at present. The peaceful use of nuclear energy brings huge benefits to humanbeings, but at the same time it also brings latent possibility of the occurrence of nuclearaccidents. The radioactive materials can bring about large-scale impact on environment in ashort time through the process of atmospheric diffusion after the occurrence of nuclearaccident. Therefore, while carrying out consequence assessment and emergency decision ofnuclear accident, the simulation of atmospheric diffusion is of great important.The atmospheric diffusion is highly random. This kind of behavior can be simulated bythe method of random walk of a great deal of particles. The random walk model ofatmospheric diffusion can reveal the essential of turbulent diffusion, has no problem ofnumerical diffusion, has clear structure of procedure and simple computation, and it veryeffective for the calculation of pollutant diffusion under non-uniform unsteady complicatedflow field with strong shear(such as sea breeze and land breeze, mountain breeze and valleybreeze,etc.).This paper used the random-walk particle-puff model, the mode is based on theimprovement of random walk mode, combined with the wind field diagnosis model.Systemresearch and study on the theory of the random-walk particle-puff model of atmosphericdiffusion and chosen an appropriate parameter determination method according to the existingdate.The system is applied to simulate the Baisha and Haiyang nuclear power plant sitesrespectively. The validation of the predicted concentration is verified in Baisha site, and themain purpose is to realize the application of the model in Haiyang site.Through the research of this thesis, we can draw a conclusion that random-walkparticle-puff model of atmospheric diffusion can simulate the atmospheric diffusion in caseof nuclear accidents very well and provide more actual information for early emergency andconsequence assessment as one atmospheric diffusion module of the nuclear emergencydecision support system.