2022 Fiscal Year Final Research Report
Multiscale management method to reduce the risk of age-related degradation of energy plant components
| Project/Area Number |
20K04177
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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 18010:Mechanics of materials and materials-related
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| Research Institution | Kyoto University |
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Principal Investigator |
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| Project Period (FY) |
2020-04-01 – 2023-03-31
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| Keywords | 原子力材料 / 分子動力学 / はじき出しカスケード / 統計学的評価 / 核生成 / 非平衡欠陥 / 中性子照射 / 照射脆化 |
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| Outline of Final Research Achievements |
A pressurized water reactor vessel is embrittled due to neutron irradiation. Non-equilibrium defects are generated inside the material due to irradiation, and they form nano-sized defect clusters, which cause irradiation embrittlement. If such nano-defect generation can be predicted based on a mechanism, it will be possible to predict and evaluate the degree of degradation of high-aged reactor pressure vessels and establish preventive maintenance measures based on it. In this study, (1) non-equilibrium defect generation rates were evaluated based on non-equilibrium defect materials science and they were formulated based on statistics, and (2) the evaluation of defect cluster nucleation phenomena was successfully made with high precision using multi-scale modeling techniques. These findings are useful for discussing embrittlement prediction methods in the framework of probabilistic risk assessment, which has recently attracted attention.
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| Free Research Field |
原子力材料
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| Academic Significance and Societal Importance of the Research Achievements |
本研究により、照射下で使われる材料内の非平衡欠陥生成および集合体核生成に関するそれぞれモデルについて、定量かつ統計学的な評価が可能になった。このような視点は、先行研究では十分に取り入れられてこなかったものであり、今後、これらの現象のモデルに取り込むことで、最終的な目標である照射脆化予測においても、確率論的もしくは統計学的に基づく評価が可能になる。こうした視点は、極値統計の議論が当然必要とされる材料脆性破壊の予測では必須であり、照射脆化予測の高度化、ひいては、軽水炉プラントの確率論的安全評価の高度化に欠かせない知見となる。
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