Establish quantitative parameters in order to prediction analysis for high level radioactive waste disposal barrier system

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04259
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22030:Geotechnical engineering-related
• Research Institution: Ashikaga University
• Principal Investigator: Nishimura Tomoyoshi 足利大学, 工学部, 教授 (00237736)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: ベントナイト / 膨張 / 熱 / 塩水 / せん断強さ / クリープ / 不飽和土 / ガス圧

Outline of Final Research Achievements

Radioactive waste disposal consists of bentonite sand mixture which is placed deep underground that is estimated 500 m. The bentonites have high swelling properties due to hydration and significant low permeability. The high swelling performance and low hydro conductively are effort to prevent the influence from disposal. Many reports and many references have focused on Thermal-hydraulic-mechanical-chemical properties that is couple properties, and underground testing, large scale test, experimental test is improve some properties. The mathematical models based on above testing data sets have some advantage This study conducted out variation tests to appear the thermal-hydraulic-mechanical-chemical properties using sodium bentonite. The develop equipment are following; Oedometer type apparatus-imposed vapor pressure technique, seepage measurement apparatus possible to correspond salinity water, thermal triaxial compression test apparatus, gas pressure measurement apparatus.

Free Research Field

環境地盤

Academic Significance and Societal Importance of the Research Achievements

本研究は高レベル放射性廃棄物地下処分施設の人工バリア材・ベントナイトの不飽和状態と飽和状態のThermal（T）-Hydro（H）-Mechanical（M）-Chemical（C）挙動を数種の試験装置の開発を伴い室内試験を実施し明らかにした。熱的作用、浸透作用、化学的作用によるベントナイト砂混合体への力学特性、変形特性、ガス圧発生などに関する解析パラメータ設定に着目した。THMC挙動は連成挙動であることから明確な解析パラメータ抽出に至ることは困難であった。しかし、室内試験方法の手順などの貴重な情報を得ることができた。