Experimental study of the nozzle size effect on aerosol removal by pool scrubbing

Abstract

Pool scrubbing is the phenomenon of removing contaminants by injecting a contaminated gas into a water pool. In the nuclear industry, this technique is used as a method to reduce the release of radioactive materials into the environment during severe accidents. In this approach, aerosol particles are removed through interactions between the injected gas and water so that properties, such as the pool height, pool temperature, gas flow rate, and steam fraction are important in determining pool scrubbing performance. In particular, since the size of the injection nozzle is a crucial factor when evaluating the velocity, flow regime, and bubble size of the injected gas, experimental studies are needed to observe the bubble behavior and aerosol removal effect due to the size of the nozzle. In this study, visualization experiments were conducted to observe the behavior of the injected gas using a high-speed camera to analyze the effect of nozzle size on pool scrubbing efficiency, and aerosol removal experiments were also performed. Additionally, the experimental results were simulated using a pool scrubbing code. In the visualization experiments, as the nozzle size increased, the gas injection velocity decreased, and the globule size at the nozzle inlet increased. In the aerosol removal experiments, the decontamination factor (DF) decreased from 197 to 6.2 as the nozzle size increased from 5 mm to 30 mm. As a result of the pool scrubbing code simulations, the DF decreased with nozzle size, and the trend was the same as the experimental results.