Study about the application of acoustic agglomeration of aerosols for source term mitigation in nuclear accidents

During severe accidents of nuclear power plants radioactive material can be released from fuel and form aerosols that, even though highly unlikely, might reach the environment. There exist a number of systems to mitigate any potential emission from a nuclear power plant and, in particular, what is known as Filtered Containment Venting System (FCVS). After the Fukushima accident some investigations have been launched to boost the efficiency of those systems as much as possible under any foreseen conditions. This work deals with an experimental study about the potential application of a power ultrasonic system as an innovative approach to precondition the particle load reaching the first filtration stages of the FCVS. This study includes the design and acoustic characterization of an ultrasonic agglomeration chamber at 21 kHz in which a high intensity standing wave field is established. This system has been tested with SiO₂ aerosols of diameters of 0.3 μm, 1 μm and 2.5 μm, and polydisperse TiO₂ aerosols. The agglomeration effects have been studied, and the results compared with the theoretical model predictions.