Fracture flow of radionuclides in unsaturated conditions at LILW Disposal Facility

Adsorption experiments for radionuclides such as 3H, 90Sr and 99Tc were conducted using fractured rock collected in unsaturated zone. The released radionuclide through artificial barrier from the near surface repository can be transported by the flow of rainfall or pore water through fractures in unsaturated zone and reach to groundwater flow. Therefore, it is important to investigate transport behavior (retardation) of radionuclides through fractured rock for the safety assessment and long-term performance of repository. Fractured rock samples were collected and characterized by X-ray microtomography (XMT) analysis, which can be used to develop a more robust unsaturated fracture transport model. When fracture-filling materials are exist, distribution coefficient of 90Sr is higher than without fracture-filling materials. In this study, batch sorption distribution coefficient (Kd) of radionuclide was determined and used to increase our understanding of radionuclide retardtion through fracture-filling materials.22Nkc