Experimental study of the steam condensate dripping behavior on the containment dome

•Experimental study on the condensate dripping mechanism.•Description of condensate flow patterns on a plate with the same surface condition with CAP1400 inner containment wall.•The effects of air, surface sub-cooling and pressure on regional dripping fraction are discussed. Under accident conditions of CAP1400, recycling of condensate film from the inner containment wall is a significant aspect for the water level maintenance of the in-containment refueling water storage tank, whilst dripping from the containment dome is the dominant factor that causing the condensate loss. Therefore, experimental investigations on the dripping phenomena were carried out in this study. A pressure vessel was set to simulate the condensing atmosphere in the containment, in which a 1.5 × 0.6 m2 rotatable test section was suspended with similar surface condition as CAP1400. Experimental results show that the condensate flow patterns could be divided into four types. It was found that dripping was triggered by the condensate mass flow flux exceeding the critical value on an unobstructed condensing surface. Meanwhile, the dripping fraction increases with the difference between condensate mass flow flux and the critical value. Besides, the effects of inclination, bulk pressure, air concentration etc. on dripping were experimental analyzed. In general, this study hopes to provide data support and theoretical guidance for the further studies of the condensate loss under accident conditions.