Long-term mobility of uranium in the granitic KURT site using isotopic analysis and sequential chemical extraction

In this study, the long-term mobility of natural uranium in the KAERI Underground Research Tunnel (KURT) site was investigated using sequential chemical extraction and isotopic analyses of natural uranium in granite. It was found that uranium(VI) would be leached out due to preferential leaching of ²³⁴U relative ²³⁸U and concentrated by an uraniferous enrichment process through long-term interactions with the oxic KURT groundwater. Our results also suggest that the migration of the preferentially released uranium(VI) through fractured granite can be significantly retarded by secondary mineral phases formed by the weathering processes of granite. (author)