Realistic modeling approach for tracer migration and retention in fractured crystalline rocks from the Grimsel Test Site

グリムゼルテストサイトの亀裂性結晶質岩におけるトレーサー移行・遅延の現実的モデル開発アプローチ

舘 幸男  ; 伊藤 剛志*; 深津 勇太  ; 赤木 洋介*; 佐藤 久夫*; Hu, Q.*; Martin, A. J.*

Tachi, Yukio; Ito, Tsuyoshi*; Fukatsu, Yuta; Akagi, Yosuke*; Sato, Hisao*; Hu, Q.*; Martin, A. J.*

In order to develop a realistic model and reliable parameters for long-term safety assessments of geological disposal, it is necessary to understand and quantify the effects of heterogeneities found around the fractures on RN transport processes in fractured crystalline rocks. This paper presents a comprehensive approach developed for coupling laboratory tests, microscopic observations and modeling in order to understand and quantify tracer transport processes occurring in natural fracture, using different types of fractured granodiorite sample from the Grimsel Test Site (GTS), Switzerland. Laboratory tests including through-diffusion, batch sorption and flow-through tests using five tracers with different retention properties indicated that tracer retention was consistently in the sequence of HDO Se Cs Ni Eu. Microscale heterogeneities around the fracture were clarified and quantified by coupling X-ray computed tomography and electron probe microanalysis. Realistic model incorporating heterogeneities around the fracture and their properties provided a much better interpretation for breakthrough curves of all tracers.