2022 Fiscal Year Final Research Report
A Study on Thermo-Hydro-Mechanical Coupled Model in Buffer Material as an Engineered Barrier in Geological Disposal
Project/Area Number |
20K05383
|
Research Category |
Grant-in-Aid for Scientific Research (C)
|
Allocation Type | Multi-year Fund |
Section | 一般 |
Review Section |
Basic Section 31010:Nuclear engineering-related
|
Research Institution | Okayama University |
Principal Investigator |
Sato Haruo 岡山大学, 自然科学学域, 准教授 (50421615)
|
Project Period (FY) |
2020-04-01 – 2023-03-31
|
Keywords | 地層処分 / 緩衝材 / ベントナイト / モンモリロナイト / 膨潤応力 / 膨潤力 / 温度依存 / 熱力学 |
Outline of Final Research Achievements |
In this study, we focused on the hydration reaction of cations in the interlayer of montmorillonite, which is the major component of bentonite, used as a buffer material in the geological disposal of high-level radioactive waste, for the swelling stress of the bentonite, and obtained the thermodynamic data of the interlayer water. We also developed a thermodynamic model which can analyze the effect of temperature on the swelling stress of bentonite, based on thermodynamic theory. We measured the thermodynamic data of Ca- and K-montmorillonite in addition to Na-montmorillonite. Additionally, since Thermo (temperature)-Hydro (water)-Mechanical (swelling stress) (T-H-M) coupled processes proceed in the buffer material, we modelled thermal and water diffusivities for buffer material and surrounding rock mass, and calculated temperature, moisture and swelling stress distributions. The practicality of the model was verified by comparing with measured data.
|
Free Research Field |
原子力工学
|
Academic Significance and Societal Importance of the Research Achievements |
緩衝材の膨潤応力について、温度の影響も解析できるこれまでになく汎用性の高い熱力学モデルを開発した。これにより、様々なベントナイト、珪砂混合率、乾燥密度などに対して膨潤応力の解析が可能となる。また、初めてNa型のほかCa型やK型モンモリロナイト層間水の熱力学データを取得した。これらのモデルやデータは他に類がなく、学術的にも貴重である。更に、緩衝材中の熱(T)-水(H)-応力(M)の連成モデルを開発し、温度、水分、膨潤応力の各分布の経時変化を解析した結果、実測データを概ね再現し、モデルの実用性が示された。地層処分における人工バリアの設計や長期挙動解析などの側面で、学術的にも社会的にも意義は大きい。
|