Fracture Sealing by Mineral Dissolution and Precipitation at Yucca Mountain

Timothy J. Kneafsey, Patrick F. Dobson, Eric L. Sonnenthal, John A. Apps, and Nicolas Spycher

Contact: Timothy J. Kneafsey, 486-4414, TJKneafsey@lbl.gov

Research Objectives
The emplacement of heat-generating waste at the proposed Yucca Mountain repository site will induce several processes to occur. Water naturally present in the rock will evaporate or boil, and this vapor will condense at a distance from the proposed repository, where the rock is cooler. The condensate will dissolve the host rock (tuff), and the dissolved constituents will precipitate if the water is boiled away. Mineral precipitation in fractures above the proposed repository could plug flow paths and reduce the probability of water seeping into the proposed repository. Our research objectives are to provide a better understanding of (1) tuff dissolution under conditions expected in the proposed repository, (2) mineral precipitation in fractures, and (3) how these processes might affect the performance of such a proposed repository.

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