核电厂野外示踪试验的三维数值模拟研究

为深入分析国内某拟选滨海核电厂址的大气扩散特征，在现场野外示踪试验的基础上，采用计算流体动力学（CFD）软件Fluidyn-PANACHE，结合三维GIS、结构化贴体网格构建、区域加密等技术方法，创建了可模拟野外示踪试验的精细化大气扩散模拟系统.相比于高斯模式，CFD模式能够更好地模拟示踪剂在不同下风距离处的峰值浓度和烟羽宽度，对近场及复杂下垫面条件下的扩散模拟更贴合实际，且可在稳态模拟的基础上获得连续变化风场中接近实时模拟的仿真效果.模拟结果的偏差统计分析表明，CFD稳态模拟和高斯模拟的统计学评价指标均位于国际公认的可接受范围内，CFD模拟的随机偏差优于高斯模拟.因此，CFD模式可用于辅助和优化其他核电厂址的野外示踪试验工作，提高我国核安全审评的效率和针对性.

Three dimensional numerical simulation of field tracer experiment for atmospheric dispersion around a domestic nuclear power plant

To further analyze the characteristics of atmospheric dispersion around a domestic coastal nuclear power plant on the basis of field tracer experiments, Fluidyn-PANACHE, a Computational Fluid Dynamics (CFD) software, was used to create a refined atmospheric dispersion simulation system that is capable of simulating field tracer experiment. More reasonable simulation for tracer's peak concentration and plume width at each downwind sampling arc, closer to real dispersion status at near field with undulate terrain, and approximate real time simulation under continuous variation of wind direction based on the steady simulation can be obtained by CFD mode compared to Gaussian mode. The statistical analysis for bias of numerical simulations indicated that both the statistical performance indices of CFD steady simulation and Gaussian simulation were within internationally accepted ranges and moreover, random bias of CFD simulation was superior to that of Gaussian simulation. It was concluded that CFD simulation can be utilized to assist and optimize field tracer experiments for other nuclear power plants so as to improve efficiency and pertinence of nuclear safety regulation.