Numerical Simulation of a Low Altitude Nuclear Explosion Test Radioactive Plume Diffusion Based on RAMS/CFORS II Model

Transport and deposition processes of a low altitude nuclear explosion test plume were simulated by using RAMS/CFORS II model.CFORS II model implemented in RAMS/CFORS,can be used to simulate long-distance transport and deposition processes of nuclear explosion test radioactive plume.A good agreement was gotten through comparison between simulation results and observed data.And some other conclusions were found.The trough system on low-middle troposphere had played an important role in the horizontal transportation and vertical diffusion of this test plume.The velocity of plume long-distance transportation decreased with altitude,and the test plume above 6 000 m moved towards sea after 48 h and under 6 000 m,the diffusion and deposition processes of the plume were sustained beyond 5 d.During 2 d after test,deposition was dominated by big particles,but later fine particles seemed to be the main component of the deposition.The radioactivity of fine particles was much lower than that of big particles.On the 4th day after test,the radioactivity of deposition decreased about 3 levels,but the deposition area of fine particles was 5 times more than that of big particles.