The Overview of Natural Circulation Characteristics of a Marine Reactor under Ocean Condition

Marine reactor would be influenced by ocean conditions such as rolling, inclination and heaving which made system coolant fluctuate and changed the ability of natural circulation of the system. The paper summarizes the study of effects of ocean conditions upon flow characteristics of natural circulation, including the researches of Japan, South Korea and China. The result shows that the ocean conditions have some effects upon natural circulation, and the structure of the loop would affect the experiment result. Generally, Inclination would reduce the ability of natural circulation, the larger the inclination angle, the more decrease the ability of natural circulation. Rolling would cause core flow rate oscillation and the amplitude of oscillation increases as rolling angle increase and rolling period decrease. Heat transfer in the core is enhanced by the rolling motion and the enhancement is thought to be caused by the internal flow due to rolling motion. The flow oscillation caused by rolling motion would overlap the density wave oscillation which made the system more instable. Heaving would also cause core flow rate oscillation and the amplitude of oscillation increases as heaving acceleration increase and heaving period increase. It is also found that the improved RETRAN procedure can be used to simulate the thermal-hydraulic characteristics of marine reactor under ocean conditions. The parameters of the current experiment have some differences with the actual condition of the marine reactor, so some further research should be done.