Influence of the mode of matrix porosity determination on matrix diffusion calculations

Ota, Ken Ichiro; Möri, Andreas; Alexander, W. Russell; Frieg, Bernd; Schild, M.

doi:10.1016/s0169-7722(02)00139-0

Cited by 31 publications

(16 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The process of drilling and subsequent sample treatment for laboratory testing can create new cracks and microcracks through stress release and disturbance (e.g., Autio et al, 1998;Bradbury and Stephen, 1986; Skagius and Neretnieks, 1986; Tullborg and Larson, 2006;Vilks et al, 2003). Increased porosity values in laboratory samples due to artificially disturbed conditions compared to in situ conditions have been well documented in previous studies (e.g., Jokelainen et al, 2013;Ota et al, 2003; Tullborg and Larson, 2006). These differences are even more pronounced in laboratory experiments when using smaller and thinner samples (Tullborg and Larson, 2006;Valkiainen et al, 1996).…”

Section: Introductionmentioning

confidence: 85%

Matrix diffusion and sorption of Cs+, Na+, I– and HTO in granodiorite: Laboratory-scale results and their extrapolation to the in situ condition

Tachi

Ebina²,

Takeda³

et al. 2015

Journal of Contaminant Hydrology

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 85%

Matrix diffusion and sorption of Cs+, Na+, I– and HTO in granodiorite: Laboratory-scale results and their extrapolation to the in situ condition

Tachi

Ebina²,

Takeda³

et al. 2015

Journal of Contaminant Hydrology

View full text Add to dashboard Cite

“…Estimates by Skagius and Neretnieks [1986] indicated a 2–3 times higher porosity in the drill core samples compared to intact rock at repository depth in situ conditions. Ota et al [2003] claim that 30 to 60% of the porosity measured by conventional laboratory techniques is an artifact by stress release and physical disturbance. No estimates of the changes in properties caused by the stress release have been made within this project, thus measured porosities and diffusivities can be regarded as maximum values.…”

Section: Overview Of the Site And Samplingmentioning

confidence: 99%

Sorbing tracer experiments in a crystalline rock fracture at Äspö (Sweden): 1. Experimental setup and microscale characterization of retention properties

Widestrand

Byegård

Cvetković

et al. 2007

Water Resources Research

View full text Add to dashboard Cite

[1] Mineralogical and retardation properties of rock materials responsible for water-rock interaction in in situ migration experiments with sorbing radioactive tracers were studied in laboratory experiments. The porosity was studied by water saturation measurements and the PMMA method was used for detailed porosity characterization of heterogeneity distributions and porosity profiles toward the fracture surface. Mylonite and altered diorite sampled in the rim zone of the fracture and representative bulk rock types were investigated by batch sorption measurements with crushed materials and through-diffusion and in-diffusion experiments in intact rock pieces. Autoradiography was used for visualization of in-diffusion profiles of sorbing tracers. The use of detailed porosity information and quantitative data on heterogeneity in porosity is shown to significantly improve the interpretation and evaluation of laboratory-scale diffusion experiments. We show through the combined approach of detailed porosity characterization and laboratory sorption and diffusion investigations that we can distinguish retention properties of bulk rock and altered rock and provide qualitative and quantitative data of heterogeneous rock properties that expand the possibility for including relevant processes in the interpretation of the results of in situ tracer tests.

show abstract

“…%) compared to the granodiorite host rock [11]. The core was drilled with a special 11 cm ring and 3 cm over-coring and resin polymerization technique, which however cannot completely prevent expansion of the over-cored natural fracture due to host rock pressure release [12]. The uneven core edges resulting from tearing out the core were sawed and flattened.…”

Section: Laboratory Core Experimental Set-upmentioning

confidence: 99%

U, Th, Eu and colloid mobility in a granite fracture under near-natural flow conditions

Schäfer¹,

Geckeis²,

Bouby³

et al. 2004

Radiochimica Acta

View full text Add to dashboard Cite

Laboratory core migration experiments were performed in a granite fracture from the Grimsel Test Site (GTS, central Swiss Alps). The flow velocity was varied (46 m yr −1 , 94 m yr −1 , 187 m yr −1 ) and solutions with 10 −6 mol L −1 U(VI), 10 −8 mol L −1 Th(IV) and 10 −8 mol L −1 Eu(III) without (cocktail I) and with addition of 2 mgL −1 bentonite colloids (cocktail II) have been injected. Results are compared with those obtained in a field study at the GTS. Flow field-flow fractionation and ultrafiltration measurements show that U(VI) is not colloid borne, different from Th(IV) and Eu(III) which are associated with colloids in both spiked natural groundwaters with and without bentonite colloid addition. The partly unretarded U(VI) migration observed at short contact times (1-2 h) diminished under near-natural groundwater velocities (∼ 46 m yr −1 ) and only a weak retardation (R f = 19.5) could be observed. Furthermore, the U(VI) mass recovery decreased with increasing contact time and was as expected unaffected by bentonite colloid addition. A groundwater colloid mediated Th(IV)/Eu(III) migration without bentonite colloid addition could be confirmed in the core experiments but only at fast groundwater flow rates. Experiments at a water flow rate of 94 m yr −1 with cocktail II demonstrated a partially bentonite colloid facilitated transport of Th(IV) and Eu(III) with 27% and 37% mass recovery, respectively. At long tracer residence times in the flow field, no breakthrough of colloidal Th(IV)/Eu(III) could be observed in both runs, indicating the strong dependence of reaction kinetics on their mobility. Reference colloid experiments using fluorescence dye labeled carboxylated polystyrene microspheres (25 nm, 50 nm and 100 nm) revealed in general a higher recovery of smaller colloid size classes increasing with groundwater velocity. Additionally, an earlier peak arrival time of colloids and colloid-associated Th(IV) and Eu(III) was observed with respect to the conservative tracer 3 H in all experiments due to pore-size or charge exclusion effects. In general, the colloid recoveries found in the laboratory core experiments are lower than those obtained in the field studies. The decrease of colloid mobility with increasing residence time suggests the occurrence of colloid attachment to the rock surfaces even under the colloid stabilizing groundwater conditions.

show abstract

Influence of the mode of matrix porosity determination on matrix diffusion calculations

Cited by 31 publications

References 14 publications

Matrix diffusion and sorption of Cs+, Na+, I– and HTO in granodiorite: Laboratory-scale results and their extrapolation to the in situ condition

Matrix diffusion and sorption of Cs+, Na+, I– and HTO in granodiorite: Laboratory-scale results and their extrapolation to the in situ condition

Sorbing tracer experiments in a crystalline rock fracture at Äspö (Sweden): 1. Experimental setup and microscale characterization of retention properties

U, Th, Eu and colloid mobility in a granite fracture under near-natural flow conditions

Contact Info

Product

Resources

About