Study On The Diffusion Law Of Airborne Radionuclides Under Loca Of Floating Nuclear Power Plate Based On CFD

The marine floating nuclear power plant has the advantages of high safety,good flexibility and widely use,which has become a hot spot of international research.However,the complex and changeable operation environment of the ocean may bring new challenges to the operation safety of the marine floating nuclear power plant.If there is a serious accident in the floating nuclear power plant,a large number of high-level radioactive products will be released,which will threaten the health and safety of the staff on the platform and the residents nearby.In order to prevent or reduce the serious consequences of floating nuclear power plant accidents,it is very important to study the diffusion law of radionuclides under the conditions of floating nuclear power plant accidents.The study takes floating nuclear power station as the research object,carries out the numerical simulation analysis on the release and migration of gaseous radioactive substances under the LOCA of reactor,evaluates the dose of the consequences of the accident,puts forward the emergency rescue measures,which provides the basic technical support for the accident prevention and emergency response of floating nuclearpower station.The specific research is as follows:(1)In the study,the environmental release amount and release rate of radionuclides under LOCA of floating nuclear power plant are calculated to provide initial data for simulation analysis of radionuclide migration.Using MELCOR,a serious accident analysis program,the system model is built according to the reactor structure and layout of floating nuclear power plant.By adding radionuclide module(RN),the release rule of radioactive source term produced by LOCA of floating nuclear power plant is analyzed.(2)Based on CFD method,the migration of radionuclides in the environment was studied.According to the initial data of radioactive source term calculated by MELCOR program,ICEM is used to establish the simulation geometry model and grid the geometry model.The grid file is imported into FLUENT,and the simulation environment is set up.The migration and distribution of radionuclides in floating nuclear power station are studied.The area and proportion of dangerous areas in different break directions are analyzed.Based on the analysis of the combination of different parameters,such as wind speed,wind direction,platform position,The influence of different factors on radionuclide migration was studied.The results show that when the breach is located in the North(A)and South(B),the area of the island danger area is smaller than that in the West(C)and East(D),and the area of theplatform danger area is opposite;In addition,when nuclide leakage occurs,a certain rotation angle of the hull is conducive to the risk of minor accidents,and wind speed has dilution and transport effects on nuclides.(3)The classical calculation model of radiation dose is used to evaluate the consequence of the dose to the personnel under the accident condition.The results show that the effective dose of inhalation and the ineffective dose of smoke plume immersion in two hours after the accident are less than the radiation dose limit of 5mSv.On the basis of radionuclide migration law and radiation dose assessment,emergency measures for accidents are proposed from the perspective of workers on the floating nuclear power station platform and island residents.In the study,for the floating nuclear power plant which is being designed and constructed in China,it is of great scientific significance and engineering value to study the migration and diffusion law of gaseous radionuclide under severe accidents,evaluate the possible consequences and propose effective emergency measures.