The use of natural analogues to assess radionuclide transport |
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Authors: | John A T Smellie and Fred Karlsson |
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Institution: | a Conterra AB, Box 493, 751 06 Uppsala, Sweden b Swedish Nuclear Fuel and Waste Management Company, Box 5864, 102 40 Stockholm, Sweden |
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Abstract: | Predicting the long-term safety and performance of a repository for intermediate- to high-level radioactive wastes requires the evaluation of various scenarios which may influence the integrity of the repository system. One such scenario, radionuclide transport, is described, and some of the geochemical processes which serve to enhance or retard transport are illustrated with examples selected from natural analogue or natural system studies. These studies, as distinct from laboratory simulations, help considerably in understanding how near- and far-field radionuclide transport mechanisms work over geological timescales (thousands to hundreds of thousands of years), more in line with the anticipated lifespan of a repository. Processes addressed include: stability of the spent fuel UO2 matrix; bentonite backfill as a barrier to radionuclide diffusion; retention of radionuclides by absorption on fracture minerals; transport and diffusion of radionuclides controlled by interconnected bedrock porosity; geochemical influence and behaviour of repository construction materials on radionuclide transport. |
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Keywords: | Natural analogues Radioactive wastes Radionuclide retardation Radionuclide transport Repository materials |
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