With the launch of the world’s first floating nuclear power plant "Romonosov",it played a significant role in solving the energy problem in the Russian Far East.The floating nuclear power plant at sea can not only provide energy protection for the oceanic region,but also bring opportunities for the development of marine resources.However,the marine environment is complex and variable,nuclear accidents may occur during the operation of floating nuclear power plants,causing pollution of the marine environment.Therefore,we need to carry out research on nuclear accident emergency radiation monitoring to provide a basis for marine nuclear accident emergency.Based on the emergency radiation monitoring of nuclear accidents in marine floating nuclear power plants,this paper finds out relevant data to understand the methods adopted by emergency monitoring of marine environmental emergencies at home and abroad,and reads the research results of domestic and foreign scholars on the simulation of radionuclide migration and diffusion.According to the moving characteristics of floating nuclear power plants at sea,an instantaneous point source Joseph model considering ship mobility is constructed.Exploring the variation of radionuclideconcentration and spatial distribution and time of nuclear accidents,providing reference for emergency radiation monitoring of nuclear accidents,and ensuring the efficient implementation of emergency radiation monitoring of nuclear accidents at sea.The main conclusions are as follows:(1)By reviewing the marine nuclides migration model literature,the author uses the instantaneous point source Joseph model to improve the nuclide migration and diffusion model according to the marine pollution,ship pollution and other related literatures,and considering the movement of the floating nuclear power plant nuclear accident.According to the investigation of nuclear accident source items and nuclear accident emergency data of floating nuclear power plants at sea,the accident source quantity estimation and model parameters are determined,and the concentration changes of radionuclide 131 I and 137 Cs in nuclear accidents of floating nuclear power plants are simulated and study on the variation law of nuclide concentration in7 research sites.(2)The spatial distribution of radionuclide migration and diffusion in the nuclear accident of floating nuclear power plant is elliptical.The concentration of nuclide in the vicinity of the ship’s motion trajectory is the highest,and the distribution of nuclide concentration is “elliptic”.And seven research sites were selected to study the relationship between radionuclide concentration and time.The concentration of nuclide on the ship’s trajectory is the highest,decreasing from the trajectory to the periphery,the decrement is slower in the direction of motion,and the decrement is faster in the verticaldirection of the moving direction.The concentration of radionuclides in the A,B,and C research points decreased rapidly and then decreased slowly with time.The concentration of nuclides decreased the fastest at 5h after the accident;The nuclides were at the D,E,F and G research sites,the concentration of nuclides remained unchanged at 1-3h,and the concentration increased slowly at 3-15 h,and the concentration decreased gradually or remained unchanged at 15-24 h.(3)According to the spatial distribution of radionuclide concentration,the concentration of radionuclides at special points and the variation of time,the division of emergency radiation monitoring work area was formulated,and the environmental pollution area of nuclear accident was divided into five emergency radiation monitoring areas.The appropriate placement of the highest concentration of radionuclide in the trajectory area of the ship.In the two areas of the ship’s motion trajectory,a small area is used for centralized monitoring,and the radioactive concentration changes in this area are the fastest.In the areas on both sides of the ship’s motion track,it is the area where key emergency radiation monitoring work is carried out,and emergency monitoring data should be obtained as much as possible in order to verify the law of radionuclide diffusion.The model and emergency radiation monitoring measures constructed in this paper are aimed at ensuring effective and rapid implementation of emergency radiation monitoring,providing reference for marine emergency monitoring and improving emergency monitoring capabilities. |