0000000000132873
AUTHOR
J. Hartikainen
The effect of microscale pore structure on matrix diffusion—a site-specific study on tonalite
Abstract The matrix diffusion of non-sorbing tracers was studied in rocks from the Syyry area, Central Finland (SY1). The effect of alteration and weathering on rock matrix porosity and on the available pore space, which affects diffusivity, are discussed. The main rock type in the crystalline bedrock of Syyry is a slightly foliated, gray tonalite with mica gneiss inclusions as well as minor, more mafic inclusions. The total porosity and the spatial porosity distribution and microstructure of the rocks were investigated using infiltration of carbon- 14-methylmethacrylate, electron microscopy and Hg-porosimetry. The laboratory-scale diffusion experiments were performed using (1) the out-leac…
Determination of the porosity, permeability and diffusivity of rock in the excavation-disturbed zone around full-scale deposition holes using the -PMMA and He-gas methods
Abstract Three experimental holes the size of deposition holes in a KBS-3 type repository (depth 7.5 m and diameter 1.5 m) were bored in hard granitic rock in the Research Tunnel at Olkiluoto to study, among other things, the properties of the rock in the excavation-disturbed zone. In the analysis described in this report, the porosities, effective diffusivities and permeabilities of disturbed and intact rock were determined by using two novel methods: the 14 C -polymethylmethacrylate method and the He-gas method. In addition, the structure of the rock in the excavation-disturbed zone was assessed using both scanning electron and optical microscopy.
Bedrock Characterisation of Four Candidate Repository Sites in Finland As Determined by He-Gas Methods
AbstractAt the end of the year 2000, one of four sites will be chosen as the final repository site in Finland. Therefore accurate and comprehensive statistics of the bedrock characteristics such as porosity [% ] and effective diffusion coefficient [m2/s ] of these sites are of importance. Altogether 115 rock samples from the four sites were measured by different He-gas methods to achieve this goal.The results obtained indicate that the average bedrock properties at these sites are quite similar. Variations among individual samples and different rock types within one repository site were larger than variations among the averaged values of the four sites. Some indication of increased microfra…