Hostname: page-component-8448b6f56d-42gr6 Total loading time: 0 Render date: 2024-04-24T04:34:04.386Z Has data issue: false hasContentIssue false
  • English
  • Français

Diffusion Mechanisms of Strontium, Cesium and Cobalt in Compacted Sodium Bentonite

Published online by Cambridge University Press:  28 February 2011

Arto Muurinen ,
Juha Rantanen  and
Pirkko Penttilä-Hiltunen
Arto Muurinen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, Otakaari 3 A, SF-02150 Espoo, Finland
Juha Rantanen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, Otakaari 3 A, SF-02150 Espoo, Finland
Pirkko Penttilä-Hiltunen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, Otakaari 3 A, SF-02150 Espoo, Finland
Get access

Abstract

For a porous water-saturated material where diffusion in the pore water, sorption on the solid material and diffusion of the sorbed ions (surface diffusion) occur, a diffusion equation can be derived where the apparent diffusivity includes two terms. One represents diffusion in the pore-water, the other surface diffusion.

In this research diffusion mechanisms were studied. The apparent diffusivities of strontium, cesium and cobalt in compacted sodium bentonite were measured by a non-steady state method. The sorption factors were adjusted using different sodium chloride solutions, groundwater and addition of EDTA for saturation of the bentonite samples. The corresponding sorption factors were measured by a batch method.

The results suggest that cations diffuse also while being sorbed. A combined pore diffusion-surface diffusion model has been used to explain the transport and the corresponding diffusivities have been evaluated. The surface diffusivities (Ds) of Sr and Cs were 8-9·10-12 m2/s and 4-7·10-13 m2 /s respectively. The pore diffusivity eD of Cs was 3.5.10-11 m2 /s which has been used also for Sr.

The sorption mechanism of Co seems to be different from that of Sr or Cs and the results allow no specific conclusions of the diffusion mechanism of Co. The apparent diffusivity of Co ranged from 2·10-14 to 7·10-14 m2/s.

The anionic Co-EDTA seems to follow some other diffusion mechanism than the cations.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 50: Symposium STOCKHOLM – Scientific Basis for Nuclear Waste Management IX , 1985 , 617
Copyright
Copyright © Materials Research Society 1985

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Neretnieks, I., ”Diffusivities of some dissloved constituents in caznpacted wet bentonite clay -MX80 and the impact on radionuclide migration in the buffer”, KBS-TR-82-27, Stockholm 1982.Google Scholar
2. Torstenfelt, B., Allard, B., Andersson, K., Kipatsi, H., Eliasson, L., Olofsson, U., Persson, H., ”Radionuclide diffusion and mobilities in capacted bentonite”, KBS-TR-83-34, Stockholm 1983.Google Scholar
3. Eriksen, T.E., Jacobsson, A., ”Diffusion in clay - Experimental techniques and theoretical models”, KBS-TR-84-05, Stockholm 1984.Google Scholar
4. Soudek, A., Jahnke, F.M., Radke, C.J., ”Ion-Exchange Equilibration and Diffusion in Engineered Backfill”, NUREG/CP-0052, CONF-8308126—, 1984, pp. 172–203.Google Scholar
5. Crank, J., The mathematics of diffusion. (Oxford University Press, London 1956.)Google Scholar
6. Rasmuson, A., Neretnieks, I., ”Surface migration in sorption processes”, KBS-TR-83-87, Stockholm 1983.Google Scholar
7. Muurinen, A., Rantanen, J.. Ovaskainen, R., Heinonen, O.J., ”Diffusion measurements in concrete and compacted bentonite”, in Scientific Basis for Nuclear Waste Management VI, (Elsevier Science Publishing Co., Inc., 1983) pp. 777–784.Google Scholar
8. Marinsky, J.A., Ion Exchange. (Marcel Dekker, Inc., New York, 1966) p. 290.Google Scholar