冷却塔对气载放射性核素扩散影响的计算流体力学数值模拟

Computational fluid dynamics numerical simulation of the effect of cooling towers on the diffusion of airborne radionuclides

核电厂的冷却塔在正常运行时,会将部分带有一定温度的水蒸气排放到出口,并与周围的空气相混合,一部分水蒸气遇空气冷凝形成可见雾羽。本研究利用计算流体力学方法对某核电站厂址6台核电厂机组及其配套冷却塔进行模拟,研究不同风向条件下6台冷却塔及其排放的雾羽对核电厂排放放射性扩散的影响。结果表明:冷却塔排列方向与风向一致时,冷却塔对环境流场的影响距离较大,主要影响下风向1500 m范围内。当冷却塔位于机组下风向时,冷却塔排放增大1000 m范围内烟囱污染物扩散因子。随环境风速增大,冷却塔排放对烟囱污染物扩散影响减小。

During the normal operation of cooling towers in nuclear power plants,water vapor with a certain temperature is discharged through the outlet of the cooling tower,which mixes with the surrounding air.A portion of this vapor condenses and forms visible plumes.This paper uses Computational fluid dynamics(CFD)numerical simulation software to simulate six nuclear power units and their supporting cooling towers at a nuclear power plant site,and studies the impact of plumes emitted from the six cooling towers under different wind directions on the radioactive diffusion of the nuclear power plant discharge.The research results indicate that when the arrangement direction of the cooling towers is consistent with the wind direction,the influence of the cooling towers on the environmental flow field extends to a distance of approximately 1500 m in the downwind direction.When the cooling towers are located in the downwind direction of the reactor unit,the emission from the cooling towers increases the pollution diffusion factor within a 1000 m range of the chimney.As the environmental wind speed increases,the impact of the cooling tower emissions on the diffusion of pollutants from the chimney decreases.