Channeling, matrix diffusion and redox capacity in crystalline rock; some questions in connection with the geologic barrier

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Authors:Neretnieks, Ivars
Author Affiliations:Primary:
R. Inst. Technol., Dep. Chem. Eng., Stockholm, Sweden
Other:
Pac. Northwest Lab., United States
Volume Title:Proceedings of the Symposium on groundwater flow and transport modeling for performance assessment of deep geologic disposal of radioactive waste; a critical evaluation of the state of the art
Volume Authors:Nicholson, Tom, chairperson; Cole, Charles
Source:No.NUREG/CP-0079, p.447-462; Symposium on Groundwater flow and transport modeling for performance assessment of deep geologic disposal of radioactive waste; a critical evaluation of the state of the art, Albuquerque, NM, May 20-21, 1985, chaired by Tom Nicholson and Charles Cole. Availability: NTIS, Springfield, VA, United States
Publication Date:1986
Note:In English. 31 refs.; illus.
Summary:There is evidence that the bedrock at large depths is so sparsely fractured that it may not be possible to describe the flow by the normally used equivalent porous medium approach. The flow must be assumed to take place in individual channels within existing fracture planes or fracture zones. This has implications on the observability of the flow conduits and has consequences for the migration velocity and dispersion of the radionuclides. Available observations and their impact on radionuclide migration are discussed. In both studies it was concluded that the by far most important retardation mechanism for the nuclides is matrix diffusion. It has so large impact that the validation of this process over long times and over the distances involved special efforts. Past and present efforts to study this process are described. The importance of the natural redox buffer system of the rock to contain disturbances by intrusion of oxygen or due to radiolysis as well as the overall importance of a reducing environment to ensure low actinide solubilities and high sorption capacity of the rock is described. The in situ availability of the reducing minerals is still largely an open question.—Modified report abstract.
Subjects:Bedrock; Crystalline rocks; Diffusion; Eh; Engineering geology; Fracture zones; Fractures; Ground water; Hydraulic conductivity; In situ; Mathematical models; Models; Movement; Radioactive waste; Surveys; Waste disposal; Central Europe; Europe; Orebro Sweden; Scandinavia; Stripa region; Sweden; Switzerland; Western Europe; Finnejo; Fjallveden; Gidea; Studevik; Svartboberget
Record ID:1987079974
Copyright Information:GeoRef, Copyright 2018 American Geosciences Institute.
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