Radionuclide transport during glacial cycles: Comparison of two approaches for representing flow transients

Jan Olof Selroos, Hua Cheng, Scott Painter, Patrik Vidstrand

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The effect of future, transient ice sheet movement and permafrost development on transport of radionuclides from a proposed repository site is investigated using numerical groundwater flow and radionuclide transport modelling. Two different transport approaches are compared, both utilizing groundwater flow simulations of future climate conditions. The first transport approach uses steady-state particle trajectories representing temperate climate conditions, but modifies the transport velocity along the trajectories according to the changing climate. The second approach is pseudo-transient by performing particle tracking in each individual flow field representing a given time epoch.Two different climate sequences are analyzed. First, a simplified sequence is assessed in order to understand if the two different transport approaches yield significantly different breakthrough characteristics. Second, a sequence representing conditions relevant for real safety assessment applications is considered.Results indicate that the transport approach using fixed trajectories tends to significantly over predict breakthrough during permafrost conditions relative to the pseudo-transient approach. The major difference between the two approaches is related to discharge locations. The fixed trajectory approach yields discharge locations constant in time whereas the pseudo-transient approach is characterized by discharge centres moving in time according to the different climate conditions.

Original languageEnglish
Pages (from-to)32-45
Number of pages14
JournalPhysics and Chemistry of the Earth
Volume64
DOIs
StatePublished - 2013
Externally publishedYes

Funding

The first author gratefully acknowledges partial financial support from the Swedish Foundation for Strategic Research. Jan Rojmar (Grafiska Illustrationer Jan Rojmar) is acknowledged for help in the production of Fig. 1 . Anders Lindblom and Jens-Ove Näslund (SKB) are acknowledged for help in the production of Fig. 2 .

FundersFunder number
Stiftelsen för Strategisk Forskning

    Keywords

    • Fractured rock
    • Glacial cycles
    • Solute transport
    • Sweden
    • Waste disposal

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