Observation of Simulated Fuel Debris using Synchrotron Radiation

抄録

We performed three-dimensional observation of simulated fuel debris by combining synchrotron computed tomography (CT) and high-energy X-ray diffraction. The goal of this study is clarifying what kind of compound does fuel debris consist of, and by what kind of environment was fuel debris generated? To solve these problems, we tried structural analysis and morphology observation using simulated fuel debris. CT was used to make the inside of simulated fuel debris clear. The inner structure of simulated fuel debris gives us the important information which environment simulated fuel debris were formed. The observed CT image provides that a clear contrast in the zirconia-rich and concrete-rich parts. From the molten state, zirconia is first precipitated. Zirconia moves to the lower part when crystals precipitated and aggregated near the bottom surface. Phase separation caused by the difference in the composition of zirconia, and can also be observed the difference in the crystal growth mode depending on the zirconia composition.