Boundary model test of bentonite based buffer in HLW disposal pit and self-sealing evaluation

2021 Fiscal Year Final Research Report

• Project/Area Number: 18H01534
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Waseda University
• Principal Investigator: Komine Hideo 早稲田大学, 理工学術院, 教授 (90334010)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: 高レベル放射性廃棄物地層処分 / ベントナイト / 膨潤 / 自己シール性 / 模型実験

Outline of Final Research Achievements

This study quantitatively evaluated the self-sealing properties of bentonite buffer material, a key component of barrier materials, with a view to contributing to the engineering of high-level radioactive waste geological disposal. Specifically, a one-dimensional swelling and deformation test by water absorption on the top end surface, a swelling pressure test, and a self-sealing measurement experiment were conducted, and a quantitative evaluation method for self-sealing performance was proposed based on various databases obtained.
The results obtained in this study may contribute to the design of bentonite-based buffer materials from the viewpoint of self-sealing properties.

Free Research Field

土木工学，地盤工学

Academic Significance and Societal Importance of the Research Achievements

本研究成果は，ベントナイトの膨潤挙動に関する境界条件や吸水方向の影響を，定量的に事件データを取得した．さらに，境界条件や吸水方向とベントナイトの内部構造の変遷について詳細に考察し，非定常な膨潤挙動の物理モデルを提案した．この点に，学術的に高い意義がある．
また，このような学術的な意義を踏まえて，高レベル放射性廃棄物地層処分において重要なキーコンポーネントとなるベントナイト系緩衝材の自己シール性能を実験的に裏付けると共に，設計法の確立に寄与できる物理モデルの提案は，高い社会的意義がある．