2021 Fiscal Year Final Research Report
Physical properties of molten Zr1-xOx measured by aerodynamic and electrostatic levitation techniques
| Project/Area Number |
19K05332
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 31010:Nuclear engineering-related
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| Research Institution | Osaka University |
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Principal Investigator |
Ohishi Yuji 大阪大学, 工学研究科, 准教授 (20571558)
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| Project Period (FY) |
2019-04-01 – 2022-03-31
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| Keywords | 溶融ZrO2 / ガス浮遊法 |
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| Outline of Final Research Achievements |
Zr and ZrO2 were melted by aerodynamic levitation (ADL) technique. By observing the shape of the solidified samples, it was found out that a bump was formed for ZrO2 sample. The Zr sample was spherical without the bump. Such bump was not observed for Al2O3, Fe, Ni, Cu, Pd, Pt, and Au melted by ADL. On the other hand, the bump was formed for Si and Ge, which are known to expand on solidification because the densities of the solid phase of Si and Ge are lower than those of the liquid phase. This result shows that ZrO2 has a characteristic that its volume expands when it solidifies. Such volume expansion on solidification can be ascribed to the formation of bubbles or volume change between solid phase and liquid phase.
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| Free Research Field |
核燃料工学
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| Academic Significance and Societal Importance of the Research Achievements |
Zrは軽水炉の被覆管として広く使用されている元素である。また、Zrの酸化物であるZrO2は2700 ℃以上の高い融点を有しており、るつぼや耐火壁等として用いられている。ZrやZrO2の溶融物は原子炉の炉心溶融事故の際に生じると考えられており、その性質の解明は重要な課題である。本成果により、溶融したZrとZrO2の凝固時の挙動は大きく異なっており、ZrO2は凝固時に体積が膨張するという特徴を有することが明らかとなった。これはZrO2の液相と固相の密度差や凝固時の気孔の生成といったことが原因であると考えられ、炉心溶融事故における炉心溶融物の挙動評価の高度化に資する情報であると考えられる。
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