| In recent years,the world’s nuclear power industry has developed steadily,and the number of nuclear power stations has gradually increased.However,nuclear power plant accidents caused by natural factors and human error also seriously threaten living environment and physical health.For example,the Great East Japan Earthquake on March 11,2011 caused a severe tsunami,causing the cooling system and power supply of the Fukushima Daiichi Nuclear Power Station to fail,a large amount of radioactive material leaked into the atmosphere and radionuclide materials were detected.When a serious accident occurs in a nuclear power plant,radionuclides will leak out of the nuclear power plant,and it will first be lifted up with the plume,which will spread due to atmospheric turbulence.During the diffusion of radionuclides in the atmosphere,dry settlement is caused by gravity,and wet settlement is caused by rain.The distribution of airborne radionuclide sedimentation into the sea is calculated to provide a model for emergency treatment of nuclear power plant accidents,making nuclear power plant accidents more comprehensive and reliable,and also providing safety guarantees for human health and environmental protection.Based on the research results of radionuclide atmospheric fluxes into the sea at home and abroad.the key issues such as the relationship between radionuclide diffusion in the atmosphere and sedimentation into the sea are studied.Based on the existing radionuclide atmospheric migration and sedimentation models at home and abroad,the principles,development history,application scope,advantages and disadvantages of each model were investigated,and their applicability was compared to select a suitable radionuclide atmospheric flux model into the sea.According to the best atmospheric flux model,the atmospheric diffusion and sedimentation of radionuclides are calculated and analyzed.The calculation results were processed to obtain the characteristics of the radionuclide’s sedimentation into the sea mechanism.Application of CALPro Plus software first processed the meteorological data input by the Yellow Sea Meteorological Module combined with the underlying surface conditions to generate a meteorological field file,and then used the diffusion module to simulate the diffusion of 13 II pollutants in the source item in the form of advection smoke.Considering the different states and quantities of 1311 in the simulation process,coupled with the decay characteristics of radionuclides,we calculated the dry and wet sedimentation of nuclide into the sea in January 201 8 under typical conditions,and the results showed single-peak and multi-peak results of nuclide’s flux into the sea.In addition,simulation calculations were performed under the influence of different wind speeds and different release heights.The results showed that:the wind speed basically had no effect on the position where the maximum concentration appeared,and had a great influence on the nuclide concentration;the release height had both a maximum concentration position and a maximum concentration.Influence;As the release height increases,the distance between the maximum concentration position and the origin becomes larger and larger,and the maximum concentration becomes smaller and smaller.Based on the application of the CALPUFF model to the Haiyang Nuclear Power Station,the simulation results of the radionuclides flux into the sea during a major breach were analyzed.The results show that the radioactive form after the accident will have two states:gas and aerosol.The radioactive influx to the sea level near the source term is generally lower than that on land.When nuclide settles into the sea,mainly aerosol nuclide is absorbed by the sea surface by gravity sedimentation.A small number of gaseous nuclide will diffuse to swim to the sea surface,and a few of them will be reflected by the sea surface.Wet sedimentation plays a key role in radionuclide sedimentation,but wet sedimentation does not necessarily dominate in all locations. |
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