复杂街区脏弹恐怖袭击下放射性物质扩散模拟

Simulation of radionuclides dispersion under dirty bomb attack with complex street geometry

为研究复杂街区“脏弹”恐怖袭击情景下的放射性物质扩散问题,以实体街区为例,基于欧拉模型,对街区内放射性物质扩散进行数值模拟,分析并总结复杂街区结构和不同风场条件下放射性物质的扩散特征。结果发现,同一风向下,当风速小于20 m/s时,风速越大,街区下风向出口处的辐射风险越高;当风速为10 m/s时,街区下风向各出口的总辐射风险最高,风速为6 m/s时风险最低。街区复杂结构对扩散的影响随风速的增大而增大;风速小于2 m/s时,近源处易形成大面积高浓度聚集,污染物整体呈高斯分布。研究表明:发生袭击时,应避免在下风向建筑物邻近区域或密集区域以及环形区域等位置停留,疏散时也应选择远离这些区域的出口。

This paper takes a real block as the study area,simulating the radionuclides dispersion under adirty bomb attack in this block based on the Euler numerical model.Then features of the radionuclides dispersion with complex street geometry and different wind field conditions are examined and concluded. Results show that the radiological risk grows up with the increase of wind speed when it is under 20m/s with the same wind direction,that when wind speed is 10m/s,the sum of the radiological risk reaches the maximum value at the exits downwind while it is minimum if the wind speed is 6m/s,that higher wind speed witnesses more significant influence of the street complexity on the radionuclides dispersion,that the radionuclides near the source is easy to form a large high-concentrated area and present a Gaussian distribution if the wind speed is slower than 2m/s,that in circumstance of dirty bomb attacking,staying in the downwind area near the buildings,as well as the areas with densely or open circular buildings should be avoided,and evacuating from the adjacent exits should also be forbidden.