Uranium-series ages of secondary uranium minerals with applications to the long-term evolution of spent nuclear fuel

Robert Finch, Juhani Suksi, Kari Rasilainen, Rodney Ewing

    Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientificpeer-review

    20 Citations (Scopus)

    Abstract

    Uranium-series activity ratios for U(VI) minerals from the Shinkolobwe mine in southern Zaire indicate that these minerals have not experienced significant preferential loss of uranium since their formation more than 100,000 years ago. The minerals examined include rutherfordine, UO2CO3, schoepite, [(UO2)8O2(OH)12]·12H2O, becquerelite, Ca[(UO2)6O4(OH)6]·8H2O, and uranophane, Ca[(UO2)2(SiO3OH)2]·5H2O. No correlation between mineral species and mineral age was evident. The oxidative dissolution of primary uraninite (UO2+x) has maintained ground waters supersaturated with respect to all of the secondary U(VI) minerals, providing an inexhaustible source of dissolved U6+ for mineral formation and growth. As long as uraninite persists in an oxidizing environment, the assemblage of secondary U(VI) phases is determined by local ground water chemistry (including transitory changes), but not necessarily a unidirectional reaction path towards equilibrium with U(VI) minerals of lower solubility. Thus the Shinkolobwe mine displays a complex assemblage of U(VI) minerals that reflects variations in the availability of dissolved elements besides U. Similarly, for a geologic repository exposed to oxidizing waters, the assemblage of corrosion products that will form during the corrosion of spent UO2 fuel is likely to be as complex as mineral assemblages found in natural uranium deposits under similar conditions.
    Original languageEnglish
    Title of host publicationScientific Basis for Nuclear Waste Management XIX
    EditorsWilliam M. Murphy, Dieter A. Knecht
    Place of PublicationPittsburgh
    PublisherMaterials Research Society
    Pages823-830
    ISBN (Print)978-1-55899-315-0
    DOIs
    Publication statusPublished - 1996
    MoE publication typeA4 Article in a conference publication
    EventXIX International Symposium on the Scientific Basis for Nuclear Waste Management - Boston, United States
    Duration: 27 Nov 19951 Dec 1995

    Publication series

    SeriesMaterials Research Society Symposia Proceedings
    Volume412
    ISSN0272-9172

    Conference

    ConferenceXIX International Symposium on the Scientific Basis for Nuclear Waste Management
    Country/TerritoryUnited States
    CityBoston
    Period27/11/951/12/95

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