In the foreseen decommissioning and fuel debris removal plans of the damaged Fukushima Daiichi reactors, the fuel debris will be broken into small pieces using laser or mechanical cutting techniques prior to removing them from the reactor buildings. Regardless of the technique to be employed, submicron radioactive aerosol particles will be generated and dispersed in the gas volume of primary containment vessel during cutting operations. Water spray systems have been proven to be an efficient method for removing aerosol particles. And the agglomeration method by injection of water mist before spray activation has been verified to improve the aerosol scavenging efficiencies in our previous experiment results. To investigate the influence of containment vessel’s size scale on aerosol spray scavenging efficiency, comparison experiments of aerosol spray scavenging without and with water mist were conducted in both the experimental facility in the University of Tokyo (3.92 m^3^ volume, 2.5 m height, 1.5 m internal diameter) and the TOSQAN facility in IRSN, France (7 m^3^ volume, 4 m height, 1.5 m internal diameter). Since the vessel’s heights are different between two facilities, the hang time of spray droplets in gas space will differ from each other, thus cause different interaction time between spray droplets and aerosol particles, and finally lead to different scavenging efficiency. Also, the flow fields inside the vessel will be affected by the vessel’s height. The aerosol particles are mainly removed in the spray region, while the particles outside the spray region will be entrained inside the spray region first and then be removed in the spray region. So, different flow fields will also have influence on the aerosol removal process.


Effect of Containment Vessel\u2019s Size Scale on the Aerosol Spray Scavenging Efficiency With Water Mist

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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