Observation of the two-phase flow patterns for a finned assembly using neutron radiography

A test section simulating the HANARO fuel channel was constructed and a two-phase flow pattern was examined. D2O was used as the working liquid and air was used to simulate the vapor. The high-speed neutron radiography technique was applied for the test and it was performed at a beam facility of HANARO called ENF (Ex-core Neutron-irradiation Facility). The flow pattern was also investigated with the ultrasonic technique and the results were compared with those from the neutron radiography images.