2MW液态钍基熔盐实验堆气载放射性流出物近场扩散的数值模拟

气载放射性流出物在近场范围内的扩散是核设施环境影响评价研究的重要内容之一,传统的高斯模型由于受到复杂建筑物的影响导致计算结果偏差比较大,不宜用于近场扩散的数值模拟。本文采用计算流体动力学(Computational Fluid Dynamics,CFD)方法以2 MW液态钍基熔盐实验堆的拟定场址为研究对象,开展放射性气态流出物在近场范围内分布规律的研究,分析风速、烟囱高度、风向等参数对气态流出物大气弥散因子分布的影响。结果表明,对于高架排放,由烟羽抬升的影响使得风速越大近场范围的放射性核素大气弥散因子越高;在下风向建筑群迎风侧均易出现放射性核素集聚区,烟囱高度越低集聚现象越明显。本研究的结果可为熔盐堆场区辐射环境影响评价及建筑物的布局、核应急提供参考依据。

Numerical simulation to dispersion of radioactive airborne effluents in near-field of 2-MW TMSR-LF1

Background: Dispersion of radioactive airborne effluents in the near field is an important content of environment impact assessment of nuclear facilities. Due to the effect of complex building, the Gaussian plume model is not suitable for simulation of atmospheric dispersion in near field.Purpose: This paper attempts to analyze the atmospheric dispersion factors in near-field area of 2-MW liquid-fueled molten salt experimental reactor (TMSR-LF1) and provide data for environment impact assessment.Methods: Based on the building layout of proposed site of TMSR-LF1, the distribution of atmospheric dispersion factors were calculated by using method of Computational Fluid Dynamics (CFD) and the influences to the distribution of different factors were analyzed. Results: For elevated emission, because of the plume rise, the greater the wind speed is, the higher the concentration is in near field area; the pollutant accumulation areas will be prone to present at upwind side of buildings along the direction of wind.Conclusion: All these provide important data for nuclear emergency, and environmental impact assessment for TMSR-LF1.