Deep disposal of eurobitum bituminised waste: Scoping calculations of nitrate release

Eef Weetjens, Xavier Sillen, Elie Valcke

    Research outputpeer-review

    Abstract

    The Eurobitum bituminised waste produced by the former EUROCHEMIC reprocessing plant in Mol-Dessel (Belgium) contains a lot of salts, mainly NaNO3. This NaNO3 may possibly affect significantly the evolution of a radwaste repository through redox and ion exchange reactions with Boom Clay, which in Belgium is studied as a reference host formation. Yet, the leaching behaviour of NaNO3 from the Eurobiturn and its migration in the Boom Clay is rather unclear. Therefore, some scoping numerical calculations have been performed. In a first phase, we calculated the water flux towards the disposal gallery to assess the timescale of the saturation process of the disposal galleries. In a second phase, the leaching rate of NaNO3 out of the drums is compared with its diffusive removal through the Boom Clay. The water flux to the gallery was calculated at approximately 100 ml/day per metre gallery, based on the natural pressure gradient observed around the HADES Underground Research Laboratory. Different approaches were elaborated to find a NaNO3 source term for the diffusion calculations. For various ways of characterising the nitrate release, the numerical calculations generally show that the NaNO3 concentrations in the first decimetres of Boom Clay will not be much higher than 1 M. Moreover, a sensitivity analysis showed that if the nitrate is released from the bituminised waste product within 10 000 years, the Boom Clay controls the concentration profiles; if the release is slower, the source term has a more pronounced effect on the near field concentrations.

    Original languageEnglish
    Title of host publication29th International Symposium on the Scientific Basis for Nuclear Waste Management XXIX
    Place of PublicationWarrendale, United States
    PublisherMRS - Materials Research Society
    Pages735-742
    Number of pages8
    ISBN (Print)1558998896, 9781558998896
    DOIs
    StatePublished - 2006
    Event2005 - MRS : 29th International Symposium on the Scientific Basis for Nuclear Waste Management - Gent
    Duration: 12 Sep 200516 Sep 2005

    Publication series

    NameMaterials Research Society Symposium Proceedings
    Volume932
    ISSN (Print)0272-9172

    Conference

    Conference2005 - MRS
    Abbreviated titleMRS2005
    Country/TerritoryBelgium
    CityGent
    Period2005-09-122005-09-16

    ASJC Scopus subject areas

    • General Materials Science
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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