| Project/Area Number |
16K06967
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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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| Research Field |
Nuclear engineering
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| Research Institution | National Institute of Maritime, Port and Aviation Technology |
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Principal Investigator |
Hirao Yoshihiro 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (70425750)
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| Co-Investigator(Kenkyū-buntansha) |
松田 規宏 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 原子力基礎工学研究センター, 研究職 (80354760)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥3,250,000 (Direct Cost: ¥2,500,000、Indirect Cost: ¥750,000)
Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2017: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2016: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
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| Keywords | 多重層遮蔽 / 点減衰核法 / 簡易遮蔽計算 / γ線ビルドアップ係数 / 順透過スペクトル法 / 簡易計算 / 多重層遮蔽評価 / 放射線遮蔽 / γ線 / 多重層ビルドアップ係数 / 放射線遮蔽実験 / 点減衰核 |
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| Outline of Final Research Achievements |
Nuclear facilities are designed to be safe within the radiation dose limits of regulations regarding external exposures received by public and workers. The point-kernel method is often used for simple and reasonable dose evaluation of gamma-rays that penetrates a shield. However, it is originally made for a single-layer material, and cannot be applied well to a multi-layer shield that is often installed in practical applications. In this study, we reviewed the previous studies and then developed ‘a forward transmission spectrum method’ that focuses on the equilibrium spectrum inside of the shield as a new evaluation method. The dose attenuation expressed by this method follows the total dose well even if the incident energy or medium is different, and also this method can limit the influence from the front or back layer around the boundary of multiple-layer. Thus, it is shown that this method is advantageous in establishing the systematic dose expression of multiple-layer shield.
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| Academic Significance and Societal Importance of the Research Achievements |
放射線の透過線量を簡易に計算する手法は、施設の安全設計の他、事故緊急時の被ばく評価等、迅速な対応が求められる場面で必要不可欠である。実施設では、エネルギーの異なる放射線や透過中に現れる二次放射線を効果的に遮蔽するため、材質の異なる遮蔽を重ねる例がよくみられる。本研究では、近年発展した精密シミュレーションの知見を得て、簡易計算手法の見直しを行い、多重層遮蔽の合理的な線量評価に対して適用性の高い手法を開発した。今後、遮蔽計算コードへの実装を通じて、廃炉作業時の汚染土壌による被ばく評価や、放射線作業従事者を防護する簡易遮蔽の設置等、幅広い応用が期待できる。
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