Measurement of void fraction distribution in two-phase flow in a 44 bundle

Liu, W.; Nagatake, Taku ; Jiao, L.; Shibata, Mitsuhiko ; Komatsu, Masao*; Takase, Kazuyuki; Yoshida, Hiroyuki  

To improve and validate the prediction accuracy of two - phase codes, Japan Atomic Energy Agency is working on the measurement of void faction distribution in rod bundles with using wire mesh sensors, under high pressure and high temperature conditions (2MPa, 212C). The test section is a 44 rod bundle, in which two three - layer 99 wire mesh sensors are installed at two different axial positions. As the first step of the experiment, to validate the measuring system, we performed experiments in water - air system under atmospheric pressure, with using water and air flow rates as parameters. Void fraction distributions in the sub-channels of the rod bundle were derived in a wide flow pattern from bubbly flow to slug flow. The water flow rate, from the viewpoint of considering the natural circulation after reactor scrum, was lower than 600 kg/ms. The data will be used to validate the void fraction correlations and two-phase evaluation codes.