Abstract The resolidified fuel debris from the damaged Fukushima Daiichi reactors must be cut into small pieces prior to removing it from reactor buildings. Submicron radioactive aerosol particles are likely to be generated and dispersed into the primary containment vessel (PCV) atmosphere during this cutting process. However, traditional sprays cannot effectively scavenge aerosol particles with diameters in the range of 0.1–1 μm from gas environments. In this paper, a new aerosol agglomeration method is accordingly proposed employing water mist as a pretreatment to enlarge the aerosol particles prior to removing them using water sprays. First, the water mist is injected into a vessel in which aerosol particles are primarily dispersed. Following a short waiting time, subsequent spray injection is then able to more effectively remove the enlarged aerosol particles. The application of water mist was found to improve the aerosol spray scavenging efficiency by coalescing with aerosol particles under both diffusiophoresis and different coagulation mechanisms to form large-sized agglomerated mist–aerosol particles that can subsequently be removed by the water spray. The efficiency of removal is increased due to the enhanced collection mechanisms of inertial impaction and improved particle surface hydrophilicity. The optimized spray system evaluated in this study will be used to effectively control radioactive aerosol suspension inside the Fukushima Daiichi PCVs and protect workers and the public from any unknown consequences of internal radiation exposure during reactor decommissioning. The proposed method can also be applied throughout the nuclear industry to reduce the risk posed by small-sized aerosol particles during maintenance.

中文翻译：

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细水雾提高气溶胶喷雾清除效率

摘要 从受损的福岛第一核电站反应堆中重新固化的燃料碎片在从反应堆建筑物中移除之前必须切成小块。在此切割过程中，可能会产生亚微米放射性气溶胶颗粒并扩散到主安全壳 (PCV) 大气中。然而，传统的喷雾不能有效地从气体环境中清除直径在 0.1-1 μm 范围内的气溶胶颗粒。在本文中，相应地提出了一种新的气溶胶团聚方法，采用水雾作为预处理，在使用喷水去除气溶胶颗粒之前放大气溶胶颗粒。首先，水雾被注入到一个主要分散气溶胶颗粒的容器中。经过短暂的等待，随后的喷雾注射能够更有效地去除增大的气溶胶颗粒。研究发现，通过在扩散电泳和不同的凝结机制下与气溶胶颗粒聚结，形成大尺寸凝聚的雾-气溶胶颗粒，随后可以通过水喷雾去除，细水雾的应用可以提高气溶胶喷雾清除效率。由于惯性撞击收集机制的增强和颗粒表面亲水性的提高，去除效率得到提高。本研究中评估的优化喷雾系统将用于有效控制福岛第一核电站内的放射性气溶胶悬浮液，并保护工人和公众免受反应堆退役期间内部辐射暴露的任何未知后果。