Application of Planar Laser-Induced Fluorescence to Measurement of Concentration Field in the Downcomer

In recent years, inhomogeneous boron dilution has recently become one of the most important issues in PWR safety. In this paper, planar laser-induced fluorescence (PLIF) was applied to the visualization measurement of concentration distribution of boron in a downcomer channel. An aqueous solution of a fluorescent dye simulated the boron solution. The visual mixing phenomena were recorded by the high-speed camera with high-resolution information. The laser dye used here was rhodamine B(RhB), and the 532-nm laser has eliminated the Gaussian distribution. Intensity distribution was measured by one CCD, and then according to the distribution of intensity, the concentration fields in the downcomer channel can be obtained. The concentration fields under different volume flow rates were discussed. The results show the diffusion process of boron and the concentration distribution of boron, which are important for the study of inhomogeneous boron dilution in the design and research of reactor system. Besides this technique has been specially developed to improve whole-field concentration measurements, which will have the extensive application of nuclear industry.