Jet region visualization experiment and decontamination factor model development of submerged gas flow under pool scrubbing conditions

Abstract

Pool scrubbing physically removes radioactive aerosol during a severe accident in a nuclear power plant. The existing pool scrubbing analysis code had a limitation in being applicable only to the globule regime under low flow rate conditions. In this dissertation, the jet flow transition criterion was newly proposed through visualization experiments, image processing techniques, and optical fiber probe experiments under the condition of injecting air into the water, and various hydrodynamic factors were measured. In addition, a pool scrubbing experiment using aerosol particles was performed to measure the decontamination factor according to the injection speed in the upward nozzle condition. A hydrodynamic jet model was developed by creating an experimental correlation based on the data obtained through the experiment. The mechanism of the removal of aerosol particles in the jet flow was newly proposed by simulating the droplet collision, and a prediction model was developed using the decontamination factor data. As a result of verifying the decontamination factor model based on previous studies, it was confirmed that the decontamination factor prediction performance was improved compared to the existing pool scrubbing analysis code results under jet flow conditions.