Copper Corrosion in Bentonite: Studying of Parameters (pH, Eh/O2) of Importance for Cu Corrosion

Torbjörn Carlsson, Arto Muurinen

    Research output: Book/ReportReport

    Abstract

    The report describes the development of methods and equipment for studying the
    parameters (pH, Eh/O2) of importance for copper corrosion. The work involved the
    fabrication of electrodes for determining Eh and pH in compacted water-saturated
    bentonite. MX-80 and the Indian Asha 505 bentonites were used in the study.
    The redox-measurements were carried out by using electrodes prepared of Au and Pt
    wires. The pH measurements were carried out by using solid IrOx electrodes. The report
    describes testing of electrodes in different solutions and in bentonite. A destructive
    method for determining oxygen content in compacted bentonite was tested, too. The
    electrodes were used in measurements inside compacted bentonite with about the same
    density as is intended to be used in the Finnish repository for spent nuclear fuel.
    The results indicate that Au and Pt redox-electrodes and IrOx pH electrodes function in
    compacted bentonite. The oxygen measurement in bentonite seems to work, too, and
    can complement the Eh measurements. Eh-values in originally aerobic bentonite
    samples having a dry densitiy of 1.5 g/cm3
    , exhibit mostly a decrease during the first
    days, which may mainly be ascribed to the depletion of oxygen. The Eh-decrease
    thereafter is probably associated with redox-reactions involving other species than
    oxygen. In samples with a dry density of 1.8 g/cm3
    , the observed Eh-decrease is mostly
    slower. No significant difference between the Eh and pH measurements in MX-80 and
    Asha 505 could be observed.
    Original languageEnglish
    Place of PublicationOlkiluoto
    PublisherPosiva
    Number of pages34
    Publication statusPublished - 2007
    MoE publication typeNot Eligible

    Publication series

    SeriesPosiva Working Report
    Volume62

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