The Simulation Study On The Diffusion And Emission Of Anti-radiation Excavator Working Dust

With the rapid development of the modern industry in recent years, the dust discharged into the air directly or indirectly during the industrial production is becoming more and more, and the dust hazards and environmental pollution have caused a great concern of people. While the nuclear industry, as a highly sensitive business, is faced with the nuclear facilities decommission, there must be radioactive flying dust during the excavator processing in the work site. If these dust migrates to the far, a huge harm will be caused to the environment and people. Therefore, designing and implementing practical and efficient dust suppression measures in the decommission scene becomes very important. But before this, the diffusion and migration rules of radioactive dust must be studied at first.Based on the former research, combined with the practical condition during the excavator processing in the nuclear decommission, we constructed the three-dimensional physical model of the operating area. According to the fluid dynamics and the air-solid two phase flow theory, the mathematical model of air flow, dust stress and diffusion, and air-solid two phase coupling was established. Based on the CFD fluent, we applied single factor analysis, simulated the diffusion and migration of dust and the dust mass concentration distribution under different reference wind speed, ground roughness length and dust particle density. By contrasting and analyzing the simulation results, we achieved that the dust flow would have different diffusion and migration forms under the different reference wind speed. And with the speed enlarging, the diffusion area of dust flow would increase integrally. Meanwhile, the different ground roughness length also had a important influence on the dust flow. When the ground roughness length took 0.1m, dust flow had the largest diffusion area, and 0.5m had the smallest. Dust diffusion area had a nonlinear change with the ground roughness length. In addition, the diffusion and migration of the dust flow also was impacted by dust particle density. When the particle density increased from 300 kg/m3 to 5000kg/m3, the two areas having the maximum dust mass concentration in the bottom of dust flow would draw close with each other gradually and merged finally. Moreover, the dust flow had the lowest diffusion height when the particle density was 2600 kg/m3. Based on the above analysis, we could improve the dust suppression effect from decreasing the reference wind speed and enlarge the ground rough length.Besides the research on the diffusion and migration law of dust flow, the protective forest also had been studied. Based on theoretical analysis and mathematical model of the protective forest dynamic effect, we studied its outstanding effect on decreasing the wind speed, and simulated the dust suppression of protective forest. Obviously this is significant to the dust control in the nuclear decommission.