The tritiated water and iodine migration in situ in Grimsel granodiorite. Part I: determination of the diffusion profiles

Abstract

As part of the long-term diffusion project a 780 days long in situ diffusion experiment was performed at the Grimsel Test Site where several radionuclides and inactive iodine were circulated in the packered interval in granodiorite. This paper presents in situ diffusion profiles for tritiated water and iodine acquired from overcored sections of the circulation interval by out-leaching.

Imaging connected porosity of crystalline rock by contrast agent‐aided X‐ray microtomography and scanning electron microscopy

“…The samples were taken close to each other to ensure they had roughly similar composition and structure. Olkiluoto veined gneiss samples were taken from drill core ONK‐PP323 in REPRO niche (Ikonen et al ., ) and Grimsel granodiorite samples from LTD monopole 1 drill hole in AU gallery at Grimsel Test Site (Ikonen et al ., ). Five of the six faces of the samples were sealed with an epoxy resin to allow CsCl to intrude the sample from only one side.…”

“…, ; Ikonen et al. , ). Various analyses done previously on Grimsel granodiorite by SEM found grain boundaries and pores also in the range of a few micrometres (Möri et al.…”

“…Grimsel bedrock around the Grimsel Test Site consists of Grimsel granodiorite and Aare granite. A typical porosity value for Grimsel granodiorite is around 0.5-1.0% (Möri et al, 2003;Ikonen et al, 2016). Various analyses done previously on Grimsel granodiorite by SEM found grain boundaries and pores also in the range of a few micrometres (Möri et al, 2003;Kelokaski et al, 2006) but the mean pore diameter as measured by Hg-porosimetry was found to be in the nanometre range (Kelokaski et al, 2006).…”

Analysis of 3H, 36Cl, 133Ba, 134Cs and 22Na from synthetic granitic groundwater: an in situ through diffusion experiment at ONKALO

“…In-situ diffusion experiments in crystalline rock have been performed in several countries e.g. Sweden [6,7,8], Switzerland [9,10] and Canada [11,12] to demonstrate the behavior of radionuclides which might be released from the canisters into the bedrock in the disposal site of spent nuclear fuel. In 1996, in Canada series of in-situ experiments with iodide were conducted to study diffusion in sparsely fractured rock (SFR) [11,12].…”

Modeling Transport of Cesium in Grimsel Granodiorite With Micrometer Scale Heterogeneities and Dynamic Update of Kd

“…During the experiment, the concentration decrease of radionuclides was measured. After the experiment, the test‐interval section was removed by overcoring with a wide diameter drill‐bit and the in‐diffusion profiles of radionuclides in the rock core were determined in the laboratory using a variety of techniques (Ikonen et al, ; Jokelainen et al, ; Soler et al, ). From these measurements, porosity of the rock and effective diffusion coefficients and distribution coefficients of the radionuclides in the Grimsel granodiorite were determined and the results were compared to ones from laboratory experiments (Ikonen et al, ; Tachi et al, ).…”