Development of a bubble generator for the gas removal system of an experimental TMSR

In July 2002, molten salt reactor was selected as one of the six type reactors of the fourth-generation nuclear energy systems at the Generation IV International Forum (GIF). ORNL completed the conceptional design of Molten Salt Breeder Reactor (MSBR) in 1970s. In present study, a new bubble generator was designed for an experimental TMSR with an electricity power about 10 MW and was tested in an experimental loop using water as working fluid. A high speed camera was employed to record the distribution and detailed breakup process of bubbles in the generator. Meanwhile the mechanism of bubble breakup was tried to be illustrated. The experimental results showed that the bubbles had average diameters of 0.5∼0.6 mm and were uniformly dispersed in the main stream when the void fraction was in the range of 0.2%∼0.3%, satisfying the requirement of a molten salt reactor. On the other hand, sudden deceleration of the bubbles in the diverging portion of the bubble generator led to a sharp velocity gradient in the vicinity of the bubble, resulting in greater shear stress on the surfaces of the bubbles. (author)