Geochemical gradients at the near-far field interface at the FEBEX experimental gallery (Grimsel Test Site)
The study carried out in the FEBEX drift located at the Grimsel Test Site (Switzerland) aims at providing the basis to understand the major geochemical conditions prevailing in crystalline rock and at the bentonite/crystalline rock interface. The FEBEX experiment, based on the Spanish concept for a high level waste repository, offers the possibility to study the mass transfer at the near field-far field interface. The chemical composition of the waters obtained in 19 radial boreholes is the result of interaction with the granites, as shown by the saturation indexes of the minerals considered. Therefore, they are diluted granitic waters, with short residence times, but longer than 50 years, according to their tritium content (3H). The slight compositional variations among the three types of waters would correspond to differences in their residence time; the permeability value of the section where the sample was taken and the selective interaction with some secondary mineral of the fracture fillings. Some evidences of mass transfer between bentonite and granite have been detected, since tracers installed at the external surface of some bentonite blocks have been determined in one packed-off section of the borehole drilled at 20 cm from the bentonite surface.
P.Gómez B.Buil A.Garralón M.J.Turrero L.Sánchez J.M.Durán
CIEMAT, Unidad de Barreras de Ingenieria y Geológica,Departamento de Medio Ambiente, Madrid, Spain
国际会议
第十二届水-岩相互作用国际研讨会(P0roceedings of the 12th International Symposium on Water-Rock Interaction)
昆明
英文
583-586
2007-07-31（万方平台首次上网日期，不代表论文的发表时间）