| 講演要旨(和文) | | 我が国における原子炉施設の建設に際しては,地質境界や断層などの不連続構造の把握および地盤の強度・変形特性の把握を目的として,原子炉建屋基礎面直上部で試掘坑を掘削し,その坑内において壁面観察,原位置試験等の調査を実施している.また,使用済燃料中間貯蔵施設の建設については,原子炉と同程度の耐震安定性が要求されることから,原子炉に準じた調査が必要となる.今回,著者らは使用済燃料中間貯蔵施設の建設にあたり,調査用の試掘坑を掘削せず,ボーリング孔を利用し,使用済燃料貯蔵建屋設置位置の直下地盤を対象とした孔間反射法地震探査を実施した.調査の結果,地質構造を連続的かつ詳細に把握できることを確認した.本稿では,その調査結果を紹介するとともに,類似施設の地盤調査への適用に対する展望を示す. |
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| | 講演要旨(英文) | | It is important to delineate subsurface structure in high resolution to construct nuclear power facilities. For this reason, test adits are excavated for subsurface investigations at nuclear power plants in Japan. At a test adit, we can observe the rock mass directly and judge whether or not faults exist. In addition, we can measure mechanical properties of the rock mass by in-situ tests. However, finishing such an investigation requires substantial costs and time. In this study, we applied a geophysical technique in a subsurface investigation at a planned spent fuel interim storage facility. It is well known that one of the advantages of geophysical techniques is that it can quickly delineate subsurface structure in a spatial manner. A cross-hole seismic reflection technique was adopted to delineate subsurface structures just beneath the facility resulting in high resolution with a spatial extent. As a result, we succeeded to confirm that there are no discontinuities and active faults in this site. This result shows that a cross-hole seismic reflection technique can serve as an alternative to the test adit investigation, and it is applicable to investigations at this kind of facilities in the future. |
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