[1D14-19] Migration in Host Rock

[1D18] A Study on Invasion Behavior of Buffer Material into a Neighboring Rock Fracture Considered Density Distribution Change in Buffer Material Based on Particle Diffusion Model

*Kengo Yamanaka¹, Haruo Sato¹ (1. Okayama University)

Keywords:High-level Radioactive Waste, Geological Disposal, Rock Fracture, Diffusion Equation, Particle Diffusion Model

In Japan, a high-level radioactive waste generated by reprocessing spent fuel from nuclear power plants is to be buried by geological disposal. Engineered barriers used for the geological disposal are composed of vitrified materials, overpack, and buffer material. Since buffer material is directly contacted with the rock mass, if there are fractures in the surrounding rock mass, invasion of buffer material to fractures is possible to cause density loss. In previous studies, invasion experiments of buffer material were conducted to fractures reproduced with acrylic discs, and an empirical expression was derived in which invasion distance to fracture was proportional to the square root of time, but the invasion distance tended to converge in long term.
In this study, we analyzed invasion radius of buffer material into fractures and the change in density distribution in buffer material and in fractures due to intrusion into fractures, and considered convergence of invasion phenomenon.