核事故下源项排放率对放射性物质大气扩散及沉降的影响

在研究核事故下放射性物质大气扩散模拟的过程中,源项排放率对放射性物质大气扩散及沉降的影响是一个关键问题。使用不同类型的假设源项模拟核事故下放射性物质的排放,并探究可以造成较高核污染水平的源项类型。结果表明,模拟得到的放射性物质地表沉降值受到源项排放类型和排放起始时间很大影响。在所有的模拟中,无论排放起始时间如何设置,一次性排放导致的污染面积均大约为连续排放的3倍。结论表明,在下风向且高降水量区域,一次性排放比连续排放更容易造成较大的污染面积,此外,排放源越接近一次性排放,风场和降水的瞬时影响越关键,那么对源项排放率的估计以及风场和降水的模拟精确度的要求越高。

Impact of the emission rate on transport and deposition of radionuclides under nuclear accident

The Correlation between the emission rate and the distribution the ground deposition of the radionuclides is necessary to be detected when studying the uncertainty of the simulation of transport and deposition of radionuclides from nuclear accidents. In this study, different types of hypothetical emissions are conducted to examine which type of emission may cause high level ground depositions. The results show that the simulated ground depositions are significantly affected with different emission rate and starting time. In all cases, the transient emission causes the contaminated area 3 times than that the continuous emission causes no matter when the emission starts. In the downwind and high precipitation area, the transient emission can more easily lead to large area of contaminated region than the continuous emission, moreover, if the real emission is close to be transient, the accuracy of the prediction for the wind field, precipitation and the emission rate should be higher.