Research On Prediction Technology Of Radioactive Pollution Atmospheric Diffusion Based On Global 3D Grid

After a nuclear attack on a battlefield or an attack on a nuclear facility,radioactive liquids or solid particles are suspended in the air to form radioactive aerosols,which,under the action of atmospheric motion,diffuse around and form radioactive pollution areas.Only by predicting the temporal and spatial distribution of radioactive pollution in the future can we guide the army to carry out early protection and minimize the harmful consequences of radioactive pollution.Using nuclear radiation monitoring data to actively respond to nuclear attacks or attacks on nuclear facilities,we can accurately estimate the source term of radioactive material release in a relatively short period of time,and then predict the harmful consequences of radioactive pollution,so as to maximize the effectiveness of emergency operations.The main work and conclusions of this paper are as follows:1.The influence of Euclidean space and spherical manifold space on the calculation results of radioactive pollution diffusion in large area is analyzed.On this basis,a simple and feasible global 3D grid construction method and coding scheme are designed.By sorting out the characteristics of various data involved in the prediction of radioactive pollution,it is proposed that the global 3D grid model be applied to the organization and management of all kinds of data involved in radioactive pollution prediction.The ideas and methods of data gridding,metadata standardization and data storage and query are given.Compared with Oracle Spatial database,the experimental results show that: Data organization and management of pollution prediction based on global 3D grid model is superior to commercial Oracle Spatial database in data import,index establishment and regional data query,which is more efficient than Oracle Spatial database;2.A framework of atmospheric diffusion model of radioactive pollution based on global 3D grid is proposed.By designing cellular neighborhood model,evolution rules of radioactive pollution atmospheric diffusion and index method for fast acquisition of cellular state,a numerical calculation method of radioactive pollution atmospheric diffusion based on cellular automata is proposed,which combines radioactive pollution atmospheric diffusion model with cellular automata.Comparing with wind tunnel experimental data,the results show that the cellular automaton model of atmospheric diffusion of radioactive contamination based on global 3D grid presented in this paper has better accuracy.This method makes it easier and more efficient to deal with the temporal and spatial variations of source terms and meteorological fields,and the dynamic transport and transformation of pollutants.It provides a reliable and feasible method for the prediction of atmospheric diffusion of radioactive pollution;3.In order to predict the radioactive pollution of "unknown" source terms by usingthe location of each monitoring point,monitoring data and meteorological data,Based on the global 3D grid model,this paper establishes the objective function of source inversion by using the most frequent value theory,and combines the individual coding and decoding strategy based on the global 3D grid model with the genetic algorithm which optimizes the genetic operator.A source inversion model based on the linear Gauss plume diffusion model is constructed.The validation test of wind tunnel test data shows that the source term inversion model constructed by the "global 3D grid model +linear Gaussian plume model + optimized genetic algorithm" proposed in this paper can invert the source term.The difference between the predicted value of pollution diffusion prediction based on the inverted source term and the actual measured value is not more than 5 times,and the predicted result is acceptable.The efficiency of data organization and management based on global 3D grid model is superior to Oracle Spatial database.The cellular automata model and source term inversion model proposed in this paper are feasible and reliable for the prediction of radioactive pollution atmospheric diffusion.