Retardation mechanism studies for performance assessments

Kari Rasilainen, Pirkko Hölttä, Marja Siitari-Kauppi, Juhani Suksi, Jarmo Lehikoinen, Matti Valkiainen, Jussi Timonen, Antero Lindberg, Nuria Marcos

    Research output: Book/ReportReport

    Abstract

    Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.
    Original languageEnglish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages90
    ISBN (Electronic)951-38-5825-1
    ISBN (Print)951-38-5824-3
    Publication statusPublished - 2001
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Meddelanden - Research Notes
    Number2096
    ISSN1235-0605

    Fingerprint

    performance assessment
    sorption
    natural analog
    modeling
    matrix
    bedrock
    channel flow
    boulder
    repository
    radioactive waste
    diffusivity
    helium
    radionuclide
    anion
    experiment
    porosity
    permeability
    timescale
    mineral
    gas

    Keywords

    • nuclear waste management
    • repositories
    • performance testing
    • radionuclides
    • migration
    • diffusion
    • sorption
    • modelling
    • bedrock
    • porosity

    Cite this

    Rasilainen, K., Hölttä, P., Siitari-Kauppi, M., Suksi, J., Lehikoinen, J., Valkiainen, M., ... Marcos, N. (2001). Retardation mechanism studies for performance assessments. Espoo: VTT Technical Research Centre of Finland. VTT Tiedotteita - Meddelanden - Research Notes, No. 2096
    Rasilainen, Kari ; Hölttä, Pirkko ; Siitari-Kauppi, Marja ; Suksi, Juhani ; Lehikoinen, Jarmo ; Valkiainen, Matti ; Timonen, Jussi ; Lindberg, Antero ; Marcos, Nuria. / Retardation mechanism studies for performance assessments. Espoo : VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).
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    author = "Kari Rasilainen and Pirkko H{\"o}ltt{\"a} and Marja Siitari-Kauppi and Juhani Suksi and Jarmo Lehikoinen and Matti Valkiainen and Jussi Timonen and Antero Lindberg and Nuria Marcos",
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    Rasilainen, K, Hölttä, P, Siitari-Kauppi, M, Suksi, J, Lehikoinen, J, Valkiainen, M, Timonen, J, Lindberg, A & Marcos, N 2001, Retardation mechanism studies for performance assessments. VTT Tiedotteita - Meddelanden - Research Notes, no. 2096, VTT Technical Research Centre of Finland, Espoo.

    Retardation mechanism studies for performance assessments. / Rasilainen, Kari; Hölttä, Pirkko; Siitari-Kauppi, Marja; Suksi, Juhani; Lehikoinen, Jarmo; Valkiainen, Matti; Timonen, Jussi; Lindberg, Antero; Marcos, Nuria.

    Espoo : VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).

    Research output: Book/ReportReport

    TY - BOOK

    T1 - Retardation mechanism studies for performance assessments

    AU - Rasilainen, Kari

    AU - Hölttä, Pirkko

    AU - Siitari-Kauppi, Marja

    AU - Suksi, Juhani

    AU - Lehikoinen, Jarmo

    AU - Valkiainen, Matti

    AU - Timonen, Jussi

    AU - Lindberg, Antero

    AU - Marcos, Nuria

    PY - 2001

    Y1 - 2001

    N2 - Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.

    AB - Performance assessments of geological repositories for nuclear waste require information about how possibly escaping radionuclides will be transported through the bedrock. Retardation mechanism studies provide an important part of the database required. So far Finnish performance assessments have considered sorption and matrix diffusion as retardation mechanisms. In this report we discuss how the data supplied by experimental retardation mechanism studies meet those required by performance assessments in the Finnish case. Experimental structural studies on small-scale pore network are discussed in detail. The C-14-PMMA method and helium-gas methods provide porosity, diffusivity and permeability data. The effort within the Palmottu natural analogue project that aimed to locate large-scale flow channels is described briefly. Specific retardation mechanism studies are discussed. The laboratory studies cover column experiments and anion exclusion studies. Column experiments provide data on sorption and matrix diffusion. The natural analogue studies cover work done in the Palmottu, the Hämeenlinna boulder, and the Hästholmen projects. Studies at Palmottu provide in situ data about sorption and matrix diffusion. This review indicates that data required by current migration models in performance assessments can be met by existing experimental methods. But the situation changes if more detailed modelling is wanted. In that case, a strategic question must be answered: what is a reasonable level of detail and conceptual rigour in performance assessment modelling, considering the unavoidable overall uncertainties due to long time scales and heterogeneous bedrock? The results obtained so far in natural analogue studies indicate that there is room for improvements in sorption modelling. The current Kd based approach could be supported by parallel mechanistic sorption modelling. It is acknowledged, however, that mechanistic sorption modelling is possible for neither all nuclides, nor all minerals, nor all geochemical conditions. Notwithstanding this, it would nevertheless better utilise the current state-of-the-art understanding of sorption.

    KW - nuclear waste management

    KW - repositories

    KW - performance testing

    KW - radionuclides

    KW - migration

    KW - diffusion

    KW - sorption

    KW - modelling

    KW - bedrock

    KW - porosity

    M3 - Report

    SN - 951-38-5824-3

    T3 - VTT Tiedotteita - Meddelanden - Research Notes

    BT - Retardation mechanism studies for performance assessments

    PB - VTT Technical Research Centre of Finland

    CY - Espoo

    ER -

    Rasilainen K, Hölttä P, Siitari-Kauppi M, Suksi J, Lehikoinen J, Valkiainen M et al. Retardation mechanism studies for performance assessments. Espoo: VTT Technical Research Centre of Finland, 2001. 90 p. (VTT Tiedotteita - Meddelanden - Research Notes; No. 2096).