Two-phase bubbly flow occurs in Lead-cooled Fast Reactors (LFR) during tube rupture accidents in steam generators. A research initiative involving experimental and numerical studies of gas–liquid LBE two-phase flows in pool- and loop-type test rigs was proposed at Shenzhen University (SZU) and Kyoto University (KU). Experimentally, a multisensor electrical conductivity probe was adopted to measure the bubble frequency, diameter, velocity, void fraction, and interfacial area concentration (IAC) in high-temperature LBE. The performance of the probe was evaluated in an air–water loop at KU. SZU designed and built a loop-type LBE two-phase test rig (SZU-LEAF) with a test section having an inner diameter of 50 mm, length of 2000 mm, and three probe measurement positions. The designed maximum temperature and liquid superficial velocity of the LBE in the test section are 400 °C and 1.5 m/s, respectively. The experiments aimed to provide data on the LBE two-phase flow in the bubbly flow regime to verify and modify the closure models for interphase momentum interactions in the two-fluid model. Hence, the volume of fluid (VOF) method was used to track the interphase boundary evolution of single bubbles rising in an LBE pool to determine their terminal velocity and shape. This method was validated using experimental results of single gas bubbles rising in a stagnant LBE pool at KU via neutron radiography. A systematic VOF analysis of single bubbles rising in an LBE pool up to 400 °C was conducted to verify the drag force model of the single bubbles in the LBE.