钢制安全壳窄缝内气溶胶冷凝滞留实验研究

目前核电厂安全壳放射性评估中未考虑狭窄裂缝（简称窄缝）对气溶胶的滞留效果，但与常规尺寸相比，窄缝的高表面/体积比对气溶胶泄漏具有可观的滞留，评估结果过于保守。通过开展矩形直通道内气溶胶泄漏实验，获得缝高约100 μm钢制安全壳窄缝内气溶胶滞留效率，观察到窄缝通道入口区域为主要的粒子沉积区域。同时，通过在窄缝流动方向上建立并维持一定的温度梯度，模拟安全壳非能动冷却系统投运时安全壳窄缝内气溶胶泄漏过程。结果表明，窄缝对亚微米粒径气溶胶具有良好的滞留效果，温度梯度引入的蒸汽冷凝能显著提高气溶胶滞留效率至91%左右，且缩小了泄漏面积。 

Experimental Research on Aerosol Condensation and Retention in Narrow Cracks of Steel Containments

Currently, the effect of narrow cracks on aerosol retention is not taken into account in the radioactivity assessment of containment in a nuclear power plant. However, compared with the conventional size, the high surface/volume ratio of the narrow crack has considerable retention of aerosol leakage, and the assessment results are too conservative. Through the aerosol leakage experiment in the rectangular straight channel, the aerosol retention efficiency in the narrow crack of the steel containment with a crack height of about 100 μm is obtained, and it is observed that the entrance area of narrow crack channel is the main particle deposition area. Besides, by establishing and maintaining a certain temperature gradient in the narrow crack flow direction, the aerosol leakage process in the containment narrow crack is simulated when the containment passive cooling system is put into operation. The results show that the narrow crack has a good retention effect on submicron aerosol, and the steam condensation introduced by temperature gradient can significantly improve the retention efficiency of aerosol to about 91%, and reduce the leakage area.