In recent decades, a number of reports have pointed out the importance of the influence of wall wettability on gas-liquid two-phase flow with a gas-liquid or liquid-gas phase change. However, very limited experimental data can be obtained about the wall surface wettability in BWRs high-temperature condition, or in the range from 250 to 300°C. From this point of view, we conducted an experimental study of surface wettability of droplet using a pressure vessel, we measured contact angles of water droplet under various ambient pressures (7.7, 14 and 15 MPa), atmospheric gases (nitrogen and argon), and test plate materials (aluminum, stainless 304, Zircaloy). In addition, experimental correlation was derived based on energy balance. The data obtained in this study will provide more accurate assessment of heat transfer in subchannels of BWRs.
