| 講演要旨(和文) | | 地層処事業を安全に進めるためには,ベースラインと呼ばれる処分場開発前の地質特性を確実に把握する技術を開発することが必須である.この目的を達成するため,我々は北関東堆積岩分布地域をモデルフィールとして,350m級坑井の調査掘削や,様々な地質・地化学・地球物理的な調査を計画している.今回,掘削予定地周辺において,広域的な水理地質構造を把握するため,AMT法電磁探査を実施した.その結果,掘削予定地周辺の第四紀堆積物や第三系堆積岩の分布が推定された.また,掘削予定地で電気探査を実施し,深度60m付近までの比抵抗構造を求めた.その結果,不飽和領域の厚さが10〜20mくらいあることが推定された.今後はこのデータをベースとして,地下水変動に伴う比抵抗変化を捉える技術の開発を行い,また他の手法との総合解析に取り組み,地層処分場周辺の水理構造をモニタリングするためのガイドラインの構築を目指す. |
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| | 講演要旨(英文) | | In order to conduct the geological disposal of high-level radioactive waste safely, it is important to develop a baseline survey technique that investigates the geological characteristic of the disposal site before construction. We have a plan to drill an exploration boring of 350 m depth and carry out the geology, geochemistry and geophysics surveys in the North-Kanto sedimentary rock area. An AMT survey was carried out around the planned boring site in 2005. The resistivity structure of up to a depth of 2 km was analyzed, which shows the distribution of Tertiary sedimentary rocks below Quaternary sediments. An electrical survey was also conducted at the boring site and a resistivity section of up to a depth of 60 m was obtained. This site is covered with the unsaturated zone of 10 - 20 m in thickness. We will repeat the surveys and detect the resistivity changes due to the groundwater change to develop the resistivity monitoring technique for the geological disposal. Moreover, we will work on the integrated analysis with other monitoring approaches and create the guideline for monitoring the hydrogeological structure around the disposal site. |
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