Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 18, 2019 - March 19, 2019
Since tools and machines are required to securely defuel fuel debris from reactors at the Fukushima Daiichi nuclear power station, various properties of the debris should be previously examined. However, we are unable to instantaneously retrieve massive debris blocks while inhibiting the release of radioactive substances. On the other hand, it is promising to examine the properties of debris fragments retrieved with the remote controlled devices which has been used to observe inside the reactors. In the present study we aim to establish a measuring technique by which mechanical properties of the debris fragments are examined. Mechanical properties and measurable minimum size are investigated for simulated foamy zirconium particles of sizes, 500 μm and 1 mm, using nanoindentation test. Simplified sample preparation procedure is also surveyed to apply the technique to remote controlled operation in hot cells. The particle’s hardness varied between 2.79 GPa of solid grains and 1.88 GPa of porous ones. Mechanical properties of the 500 μm particles was immeasurable because the indenter slipped on the sample surface inadequately flattened. Young’s modulus and hardness of the 1 mm particles were successfully measured as 90.7 GPa and 2.36 GPa on the surface which was finally finished to a roughness Ra = 167 nm with #600 abrasive papers.
