严重事故下吸湿性气溶胶的自然去除研究

Study on Natural Removal of Hygroscopic Aerosols in Reactor Severe Accident

反应堆发生严重事故时,堆芯释放出的吸湿性气溶胶会在潮湿的安全壳内增大,从而影响其自然去除过程。本文理论推导了吸湿性气溶胶的增大模型并通过多种方法对其进行了验证。模型计算结果表明,气溶胶的增大过程由于受到溶解度的限制而存在临界湿度值,在该临界值以下时气溶胶不发生吸湿,但这未被其他严重事故分析程序所考虑。同时,基于某三代先进压水堆的特定严重事故工况,本文分析了干颗粒半径及湿度对气溶胶的平衡半径和自然去除系数的影响。结果表明:气溶胶的自然去除系数随干颗粒半径的增大将先减小后增加,并在1μm时达到最小值;相同湿度下,干颗粒半径对气溶胶半径的最大增大比例的影响不大;湿度的增加对不同干颗粒半径气溶胶去除系数的影响不同。

In the event of a reactor severe accident, the hygroscopic aerosols released from the reactor core will grow in the moist containment, thereby affecting their natural removal process. In this study, a growth model of the hygroscopic aerosols was developed and it was also validated in a variety of ways. The model calculation results shows that there is a humidity threshold in the growth progress of the aerosol particles due to the limit of the solubility and the aerosol particles do not absorb the water below this threshold, which is ignored by other severe accident analysis programs. Based on the severe accident condition of a third generation advanced pressurized reactor, the effects of the dry particle radius and the humidity on the aerosol particle equilibrium radius and natural removal coefficient were also investigated. The results show that the natural removal coefficient of aerosol particles decreases firstly and then increases with the increasing of the dry particle radius, and it takes the minimum value at 1 μm. At the same humidity, the dry particle radius has little effect on the max growth ratio of aerosol particles. The effects on the removal coefficients of aerosol particles with different dry particle radius are different.