Diffusion in the matrix of rocks from Olkiluoto - the effect of anion exclusion

Matti Valkiainen, Hannu Aalto, Antero Lindberg, Markus Olin, Marja Siitari-Kauppi

    Research output: Book/ReportReport


    Diffusion in the rock matrix is dependent on two basic factors: the effective diffusion conductivity of the rock and the rock-capacity factor. The aim of this ongoing research is to study both of these factors more closely by finding evidence and studying the significance of anion exclusion and surface diffusion. The material for the study was selected form the drill-core of the drill-hole OL-KR5 from Olkiluoto investigations site. Six rock-types were included in the study, three unaltered and three altered. The water-types selected can be divided to two groups: in one the ionic strength is varied, in the another the ionic type is varied. The diffusion measurements were carried out partly by the equilibration-leaching method, partly by the through-diffusion method. The measurements by the equilibration-leaching method were performed in the anaerobic cabinet and the through-diffusion measurement in laboratory room conditions. Radioactive isotopes 3H, 35S, 36Cl and 22Na were selected as tracers. This report contains results of the equilibration-leaching measurements and through- diffusion measurements using 3H (HTO), 36Cl (Cl-) and 35S(SO42-) as tracers. The rock-types under study were also studied in the University of Helsinki, Department of Chemistry using polymethylmethacrylate labelled with 14C revealing the pore structure. Also, results of specific surface area measurements made in BAM, Berlin are given. The comparison of results obtained by the gas diffusion method at the University of Jyvaeskylae to the results obtained by tritium are also appended.
    Original languageEnglish
    Place of PublicationHelsinki
    Number of pages38
    Publication statusPublished - 1995
    MoE publication typeD4 Published development or research report or study

    Publication series

    SeriesYJT Raportti


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