Visualization and acoustic emission monitoring of nucleate boiling on rough and smooth fuel cladding surfaces at atmospheric pressure

The purpose of this work is to evaluate nucleate boiling phenomena occurring on as-received rough and chemically etched smooth fuel claddings in water at atmospheric pressure using the visualization method and the acoustic emission technique. The onset of nucleate boiling on the smooth cladding surface occurred at higher temperature than on the rough cladding surface. The visible boiling phenomena remarkably decreased on the smooth cladding surface compared with those on the rough cladding surface. The density and energy of AE signals emitted from vapor bubbles on the smooth cladding surface decreased than those on the rough cladding tube. The variation trend of AE signals was in good agreement with the visualization results. Therefore, it is expected that the AE technique can be effectively utilized to monitor the boiling behaviors on the heated surfaces even under non-visualized conditions.