Experimental Research on Aerosol Condensation and Retention in Narrow Cracks of Steel Containments
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摘要: 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。Abstract: 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.
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Key words:
- Aerosol /
- Steel containment /
- Narrow cracks /
- Retention /
- Steam condensation
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图 1 气溶胶窄缝滞留实验装置简图
T,P—温度、压力测点
Figure 1. Schematic Diagram of Experimental Device of Aerosol Narrow Crack Retention
图 2 实验后窄缝半沉积面的气溶胶粒子沉积分布
红色椭圆圈出来的区域表示窄缝通道气溶胶粒子沉积集中在通道入口区域
Figure 2. Aerosol Particle Deposition Distribution on Narrow Crack Semi-deposition Surface after Experiment
图 3 窄缝流动方向上温度分布
Figure 3. Temperature Distribution along the Narrow Crack Flow Direction
图 4 窄缝进/出口气溶胶粒径分布
Figure 4. Particle Size Distribution of Aerosols at Narrow Crack Inlet/Outlet
图 5 窄缝进/出口气溶胶质量浓度及泄漏流量
Figure 5. Mass Concentration and Leakage Flow of Aerosols at Narrow Crack Inlet/Outlet
表 1 事故后安全壳窄缝内气溶胶滞留条件与实验条件对比
Table 1. Comparison of Aerosol Retention Conditions and Experimental Conditions in Containment Narrow Crack after Accident
关键参数 事故条件 实验条件 气溶胶 泄漏压差/ kPa 0~400 160 温度/℃ <150 130 浓度/( g·m−3) 约为1.0 0.06~0.25 质量中值粒径/μm 约为1~2 <1 载气 空气、水蒸气和氢气 空气和水蒸气 窄缝 裂缝深度/μm 约为50（弯曲、粗糙） 52
（直、粗糙）裂缝尺寸 约为 4 mm2
（等效泄漏面积）高=100 μm；
宽=3×104 μm
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表 2 窄缝内气溶胶滞留实验参数及滞留效率
Table 2. Experimental Parameters and Retention Efficiency of Aerosols in Narrow Crack
关键参数 工况A 工况B 窄缝 高×宽×长/(μm×mm×mm) 100×30×52 100×30×52 温度梯度（沿流动方向）/
(℃·mm−1)0 1 气溶胶 进口压力/kPa 260 260 出口压差/kPa 120 115 温度/℃ 130 130 粒子 TiO2 TiO2 质量中值粒径/μm ~0.9 ~0.8 水蒸气摩尔份额 0 0.8 滞留效率（η±Δη）/% 41±17 91±3
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[1] TRUPIANO A G. Assessment of basis for aerosol plugging in AP1000 containment leak paths for radiological design bases accidents: Westinghouse non-proprietary class 3[Z]. 2007. [2] KANDLIKAR S G. Fundamental issues related to flow boiling in minichannels and microchannels[J]. Experimental Thermal and Fluid Science, 2002, 26(2-4): 389-407. doi: 10.1016/S0894-1777(02)00150-4 [3] LEWIS S. Solid particle penetration into enclosures[J]. Journal of Hazardous Materials, 1995, 43(3): 195-216. doi: 10.1016/0304-3894(95)00037-U [4] MOSLEY R B, GREENWELL D J, SPARKS L E, et al. Penetration of ambient fine particles into the indoor environment[J]. Aerosol Science and Technology, 2001, 34(1): 127-136. doi: 10.1080/02786820117449 [5] GAUNTT R O, COLE R K, ERICKSON C M, et al. MELCOR computer code manuals, vol. 3: demonstration problems[Z]. 2000. [6] PAROZZI F, CHATZIDAKIS S, HOUSIADAS C, et al. Investigation on aerosol transport in containment cracks[C]//International Conference Nuclear Energy for New Europe 2005. Ljubljana: Nuclear Society of Slovenia, 2005. [7] TIAN M, GAO H E, HAN X Y, et al. Experimental study on the penetration efficiency of fine aerosols in thin capillaries[J]. Journal of Aerosol Science, 2017, 111: 26-35. doi: 10.1016/j.jaerosci.2017.06.001 [8] SUJATHA P N, KUMAR A, SEN S, et al. Experimental measurements and theoretical simulation of sodium combustion aerosol leakage through capillaries[J]. Progress in Nuclear Energy, 2020, 118: 103111. doi: 10.1016/j.pnucene.2019.103111 [9] WATANABE A, YAMADA K, OHSAKI M. FP aerosol trapping effect along the leakage paths of degraded containment penetrations during a severe accident (II): decontamination factor at the containment penetrations and its application to actual plant[J]. Transactions of the Atomic Energy Society of Japan, 2009, 8(4): 332-343. doi: 10.3327/taesj.J08.052 [10] PAROZZI F, CARACCIOLO E D J, JOURNEAU C, et al. The COLIMA experiment on aerosol retention in containment leak paths under severe nuclear accidents[J]. Nuclear Engineering and Design, 2013, 261: 346-351. doi: 10.1016/j.nucengdes.2012.12.012 [11] THOMAS GELAIN, JACQUES VENDEL. Research works on contamination transfers through cracked concrete walls[J]. Nuclear Engineering and Design, 2008, 238(4): 1159-1165. doi: 10.1016/j.nucengdes.2007.08.007 [12] ALLELEIN H J, AUVINEN A, BALL J, et al. State-of-the-art report on nuclear aerosols[Z]. 2009. [13] VINCENT J H, GIBSON H. Sampling errors in blunt dust samplers arising from external wall loss effects[J]. Atmospheric Environment (1967), 1981, 15(5): 703-712. doi: 10.1016/0004-6981(81)90274-2 -
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