Abstract—

The article presents the results from numerical modeling of aerosol particles' deposition process during their transportation in the horizontal section of the reactor plant’s primary circuit model for the conditions typical for a severe accident at an NPP equipped with VVER reactors. The effect that the bulk condensation of cesium vapors has on the growth and deposition of aerosols during their transportation is analyzed. The influence of the initial size and concentration of aerosol particles on their growth rate and subsequent deposition is considered. Homogeneous condensation occurring in the absence of heterogeneous condensation nuclei (solid aerosol particles) and also heterogeneous condensation under the conditions in which nuclei of the new phase do not emerge according to the homogeneous mechanism are considered as the limit cases. Data on the average size of the produced droplets and aerosol particles along the channel axis in the condensation zone with the varied value of aerosol particles mass fraction in the flow have been obtained, which corresponded to different ratios of the condensate mass fraction in the form of droplets and liquid layer on the surface of solid aerosol particles. It has been established that the general deposition rate decreases if the flow contains droplets generated as a result of homogeneous bulk condensation and having a size smaller than the size of grown aerosol particles. The article describes the analysis scheme of the modeled section whose geometrical shape was specified based on the horizontal section of the experimental installation in the FALCON-ISP1 series of experiments on the deposition and transport of radionuclide aerosols. The cesium vapor homogeneous-heterogeneous condensation process is modeled by numerically solving—using the method of moments—the kinetic equation for the droplet size distribution function with involvement of the authors’ COND-KINET-1 computer program. The transport and deposition of aerosol particles in the primary circuit channel were modeled using the MAVR-TA computer code developed at the National Research Center Kurchatov Institute.

中文翻译：

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带有VVER的核电站发生严重事故期间，铯蒸气本体冷凝对反应堆工厂一次回路中气溶胶传输的影响

摘要-

本文介绍了在装有VVER反应堆的NPP发生严重事故的典型条件下，气溶胶颗粒在反应堆工厂主回路模型的水平部分中运输过程中沉积过程的数值模拟结果。分析了铯蒸气的大量冷凝对气溶胶在运输过程中的生长和沉积的影响。考虑了气溶胶颗粒的初始尺寸和浓度对其生长速率和随后沉积的影响。在不存在均相缩合核（固体气溶胶粒子）的情况下发生的均相缩合，以及根据均质机理未出现新相的核的条件下的均相缩合被认为是极限情况。获得了在冷凝区中沿通道轴产生的液滴和气溶胶颗粒的平均尺寸数据，其中流中气溶胶颗粒质量分数的值发生了变化，这些数据对应于冷凝物质量分数的不同比例，形式为气溶胶颗粒表面上的液滴和液体层。已经确定的是，如果流中包含由于均相本体凝结而产生的液滴并且其尺寸小于生长的气溶胶颗粒的尺寸，则总沉积速率降低。本文根据FALCON-ISP1系列放射性核素气溶胶沉积和传输实验中实验装置的水平截面，描述了指定几何形状的模型截面的分析方案。铯蒸气的均相-非均相冷凝过程是通过使用矩量法通过作者COND-KINET-1计算机程序参与的液滴尺寸分布函数的动力学方程数值求解来建模的。使用国家研究中心库尔恰托夫研究所开发的MAVR-TA计算机代码对气溶胶颗粒在主回路通道中的运输和沉积进行了建模。