[H-CG20] Nuclear Energy and Geoscience

[HCG20-P09] In-situ Reaction and Alteration of Mudstone-Cement Interfaces at the Horonobe URL: Comparison between OPC and HFSC

*Shuntaro Dei¹, Yuki Amano¹, Yuki Sugiura¹, Masahito Shibata², Kumi Negishi², Tatsunori Yokoyama¹, Saya Kagami¹, Masaki Takeda¹, Akihito Mochizuki¹, Akitaka Sakurai¹, Yukio Tachi¹ (1.Japan Atomic Energy Agency, 2.Taiheiyo Consultant Co. Ltd.)

Keywords:Geological disposal, Horonobe URL, Cement-rock interaction, Secondary minerals, Radionuclide migration

The construction of a repository for geological disposal of radioactive waste will include the use of cementitious materials. The reaction of cementitious materials with groundwater cases high pH and Ca concentration groundwater, resulting in alteration of mudstone-cement interfaces by dissolution of rock constituent minerals and precipitation of secondary minerals, which may affect the migration behaviour of radionuclides in bedrock. The specific objectives of this study focus on the in-situ interaction between cement and mudstone at the Horonobe Underground Research Laboratory (URL) in Hokkaido, Japan, by applying various analytical methods.