Radionuclide Retardation in Granitic Rocks by Matrix Diffusion and Sorption

Abstract

Radionuclide retardation in mica gneiss, unaltered, moderately and strongly altered tonalite was studied by a thin section, batch, in-diffusion and column methods. Objectives were to examine retention processes in different scales and understand the influence of the rock matrix heterogeneity. Attempts were made for a more detailed interpretation of experiments using migration models used in performance assessments adapted for interpreting the laboratory scale experiments. Batch experiments were explained adequately using matrix diffusion-sorption model, instantaneous kinetic sorption model or model in which both mechanisms were taken into account. A numerical code FTRANS was able to interpret in-diffusion of calcium into the saturated porous matrix. Elution curves of calcium for the moderately and strongly altered tonalite fracture columns were explained adequately using FTRANS code and parameters obtained from in-diffusion calculations. Kd-values for intact rock obtained from fracture column experiments were lower than Kd-values for crushed rock indicating that batch experiments overestimate the retardation of radionuclides. Higher sorption and fair dependence on fraction size was obtained for altered tonalites due to the composition of alteration minerals and large specific surface areas.

This is a preview of subscription content, access via your institution.

References

  1. 1

    R. S. Rundberg, In: Radionuclide sorption from the safety evaluation perspective, Proceedings of a NEA Workshop, OECD (1992).

  2. 2

    H. Johansson, M. Siitari-Kauppi, M. Skålberg, E. L. Tullborg, J. Contam. Hydrol. 35 41–53 (1998).

    CAS  Article  Google Scholar 

  3. 3

    P. Hölttä, M. Siitari-Kauppi, P. Huikuri, A. Lindberg, A. Hautojärvi, In Scientific Basis for Nuclear Waste Management XX, Mater. Res. Soc. Proc. 465, 789–796 (1997).

    Article  Google Scholar 

  4. 4

    M. Siitari-Kauppi, P. Hölttä, S. Pinnioja, A. Lindberg, In Scientific Basis for Nuclear Waste Management XXII, Mater. Res. Soc. Proc. 556, 1099–1106 (1999).

    CAS  Article  Google Scholar 

  5. 5

    P. Hölttä, “Radionuclie migration in crystalline rock fractures–Laboratory study of matrix diffusion,” Doctoral Thesis, University of Helsinki. Report Series in Radiochemistry 20/2002, 55 p. + Appendices (2002).

  6. 6

    A. Lindberg, M. Paananen, Teollisuuden Voima Oy, Site Investigations Work Report 92-34, Helsinki, (1992) (in Finnish).

    Google Scholar 

  7. 7

    K-H. Hellmuth, M. Siitari-Kauppi and A. Lindberg, Journal of Contaminant Hydrology 13, 403 (1993).

    CAS  Article  Google Scholar 

  8. 8

    M. Siitari-Kauppi, “Development of 14C-polymethylmethacrylate method for the characterisation of low porosity media,” Doctoral Thesis, University of Helsinki. Report Series in Radiochemistry 17/2002, 156 p (2002).

  9. 9

    INTERA Environmental Consultants, Inc. FTRANS: A two dimensional code for simulating fluid flow and transport of radioactive nuclides in fractured rock for repository performance assessment. Houston, Technical report ONWI-426 (1983).

    Google Scholar 

  10. 10

    H. Nordman and T. Vieno, Near-field model Repcom. Rep. YJT-94-14, Nuclear waste Commission of Finnish Power Companies (1994).

    Google Scholar 

Download references

Author information

Affiliations

Authors

Corresponding author

Correspondence to P. Hölttä.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Hölttä, P., Siitari-Kauppi, M., Kelokaski, M. et al. Radionuclide Retardation in Granitic Rocks by Matrix Diffusion and Sorption. MRS Online Proceedings Library 1107, 621 (2008). https://doi.org/10.1557/PROC-1107-621

Download citation