DIFFUSION OF RADIONUCLIDES IN DEEP SEA SEDIMENTS UNDER DIFFERENT PRESSURES AND TEMPERATURES
In the absence of pore water movement the dominant transport mechanism for migrating radionuclides in seabed sediments is diffusion. Apparent diffusion coefficients measured in sediments are sensitive to chemical (eg, redox) and physical (eg, porosity) conditions. The influence of pressure on diffusion, particularly with respect to temperature, is reported here from laboratory experiments. Hitherto the effect of in-situ pressure has been overlooked or assumed to be negligible, and that of temperature to be dominant. This study attempts to clarify whether measurements made at atmospheric pressures are applicable to modelling radionuclide migration from radioactive waste canisters emplaced beneath the seabed. Three isotopes, technetium (Tc-95m), neptunium (Np-237) and plutonium (Pu-238), and two experimental configurations were used: a column method involving generation of a diffusion profile, and a half- cell technique involving measurement of the total activity transferred from a spiked to an unspiked side. Diffusion coefficients obtained suggest the absence of a pressure effect, and confirm temperature as the dominant control.
Bibliographic Reference: ORAL PRESENTATION: OXFORD (UK), SEPT. 20-21, 1988, AVAILABILITY: CEC-LUXEMBOURG, DG-XIII-C-3, POB 1907, MENTIONING PAPER EN 34265 ORA
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Record Number: 1989126116300 / Last updated on: 1989-06-01
Available languages: en