A Numerical Study of Liquid Carryover Based on the VOF Model

Liquid carryover is an important phenomenon during the small break loss of coolant accidents (LOCA). The coolant loss rate due to liquid entrained decides the decreasing height of water level and the ability that the core can be cooled. It is especially important in nuclear heating reactor as it is integral arranged without safety injection system. Therefore, the initial water volume in the reactor vessel and coolant loss rate determines whether the core could be submerged. Numerous experiments have been conducted to investigate the phenomenon of liquid carryover in the pool system. Fruitful outcomes have been proposed involving mechanism of entrained liquid produced as well as semi-empirical formula for engineering purposes. However, the semi-empirical correlations on entrainment are highly data-depended and are less applicable under different experiment settings. This paper presents a numerical method based on the VOF to study the liquid carryover in the pool system. The numerical results are analyzed with mesh independence analysis and compared with previous experiments. Several types of liquid carryover are found in the simulation. The exit effect on liquid loss rate is specifically studied including the setting of exit as well as the range that exit effect dominates.