Anomalous Transport for Radioactive Tracer in Bentonite
Abstract
Radionuclide behavior in disposal repositories is complex. The diffusion transport parameters have long been treated as constants but without solid support. We explores radioactive transport in bentonite through experiment and mechanism investigation. For the column tests with the same length, Cesium shows smaller apparent and effective diffusion coefficients than those of Tritium. The discrepancy can be attributed to the adsorption reactions of Cesium. For the column tests with the same type of tracer, the apparent and effective diffusion coefficients show an increasing trend with the column length. In the same time, the geometric factor shows a decreasing trend. According to the above observation, we propose a scale-dependent model for transport parameters to explain the trend behaviors including diffusion coefficients, retardation factor and distribution coefficient. The scale-dependent behavior may be explained by nonuniform compaction of bentonite to cause the heterogeneity of pore construction. This study sheds the light on clarifying the transport mechanisms for radionuclide behavior in bentonite.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMH034.0007H
- Keywords:
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- 1009 Geochemical modeling;
- GEOCHEMISTRY;
- 1859 Rocks: physical properties;
- HYDROLOGY;
- 5104 Fracture and flow;
- PHYSICAL PROPERTIES OF ROCKS;
- 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS