Experimental Study on Diffusion of Ni in Lead-bismuth Eutectic (LBE)

Lead bismuth eutectic (LBE) is considered as a spallation target and a coolant for the future accelerator driven system (ADS) or fast breeder reactor (FBR), due to its excellent properties. However, LBE is corrosive to structural materials like austenitic stainless steels if they are exposed to LBE directly. In order to study the corrosion phenomenon between the structural steel and liquid LBE, it is very important to investigate the characteristics of diffusion of such species in liquid LBE. A measurement of diffusion coefficient of Ni and Cr in liquid LBE was carried out by using a capillary tube in our study. The inner diameter of the thin ceramic tube was 2 mm, which was filled with liquid LBE and Ni powder was added at the top end. The tube was kept at constant temperature (550 °C-650 °C) for diffusion of Ni in an electric furnace. Then, the LBE rod in the tube was cooled down and cut into several pieces. Ni concentrations were measured from Ni contents in nitric acid solution by means of the inductively coupled plasma mass spectrometry (ICP-MS). In our experiment, because the element of Ni, Pb and Bi was highly separated in the ion exchange process, it is helpful to improve the accuracy of the experimental result. From the experimental data of Ni concentration, the diffusion coefficient in LBE was obtained.