TUFF DISSOLUTION AND PRECIPITATION IN A BOILING, UNSATURATED FRACTURE

摘要

Fracture plugging above the potential repository atrnYucca Mountain, Nevada, would reduce the probability ofrnwater seeping into the repository. We experimentallyrninvestigated the plugging of fractures due to mineralrndissolution and precipitation. Water with dissolved CO2rnwas flowed through crushed Yucca Mountain tuff at 94oCrnand the resulting water chemistry was monitored. Thernwater containing dissolved tuff constituents was introducedrninto the top of a vertically oriented non-isothermal saw-cutrnfracture in a tuff block having a temperature of 80oC at therntop and 130oC at the bottom. The fracture plugged inrnseveral days. The water chemistry is presented and thernmorphology of the precipitate is described with respect tornthe precipitation temperature.