Laboratory scale advection-matrix diffusion experiment in Olkiluoto veined gneiss using H-3 and Cl-36 as tracers

MRS Advances ◽  
2017 ◽  
Vol 2 (12) ◽  
pp. 655-660 ◽  
Author(s):  
Mikko Voutilainen ◽  
Pekka Kekäläinen ◽  
Jukka Kuva ◽  
Marja Siitari-Kauppi ◽  
Maarit Yli-Kaila ◽  
...  
Keyword(s):  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Effective Diffusion ◽  
Core Sample ◽  
Matrix Diffusion ◽  
Diffusion Experiment ◽  
In Situ Experiment ◽  
Crystalline Bedrock ◽  
In Situ Conditions

ABSTRACTSpent nuclear fuel from Finnish power plants is planned to be deposited deep in the crystalline bedrock. The bedrock needs to be well characterized to properly assess the risks inherent to the long term safety of the site. In the bedrock the possibly released radionuclides are assumed to be mainly transported by water conducting fractures and their transport is retarded by matrix diffusion and sorption. In this work transport properties of an 80 centimeters long veined gneiss drill core sample from Olkiluoto was studied using an advection-matrix diffusion experiment, which was developed to demonstrate the effect of rock matrix for transport of radionuclides in an advective fracture. The experiment was performed using H-3 and Cl-36 as tracers, and effective diffusion coefficients (De) of (1.7 ± 0.7) × 10-13 m2/s and (1.4 ± 1.0) × 10-14 m2/s and porosities of 1.1 ± 0.3 % and 0.23 ± 0.10 % were determined, respectively. A lower porosity and De for Cl-36 than for H-3 indicates an effect of anion exclusion and the results were found to be in agreement with previous laboratory experiments. However, the comparison to results from a similar in-situ experiment showed that the transport of H-3 and Cl-36 is retarded more in laboratory than in in-situ conditions by matrix diffusion.

Through diffusion study on Olkiluoto veined gneiss and pegmatitic granite from a structural perspective

MRS Advances ◽  
2016 ◽  
Vol 1 (61) ◽  
pp. 4041-4046 ◽  
Author(s):  
Mikko Voutilainen ◽  
Jussi Ikonen ◽  
Juuso Sammaljärvi ◽  
Jukka Kuva ◽  
Antero Lindberg ◽  
...  
Keyword(s):  
Pore Structure ◽  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Knudsen Diffusion ◽  
Effective Diffusion ◽  
Crystalline Bedrock ◽  
Through Diffusion ◽  
The Difference ◽  
Micrometer Scale ◽  
Pegmatitic Granite

ABSTRACTSpent nuclear fuel from Finnish power plants is planned to be deposited deep in the crystalline bedrock in Olkiluoto, Finland. The bedrock needs to be well characterized to assess the risks inherent to the long term safety of the site. In the bedrock the possibly released radionuclides are mainly transported by water conducting fractures and their transport is retarded by diffusion and sorption. In porous materials these properties are typically linked to microscopic pore structure (pore size distribution, tortuosity and constrictivity) and chemical nature of the minerals and groundwater.In this work transport properties of veined gneiss (VGN) and pegmatitic granite (PGR) samples from Olkiluoto were studied using various through diffusion experiments and the C-14-PMMA autoradiography. Through diffusion experiments were performed on rock cores using HTO and 36Cl in water phase and He in gas phase as tracers. The effective diffusion coefficients (De) determined for the VGN were found to be dependent on the tracer molecule (De(HTO) < De(He) < De(Cl)) whereas for the PGR such a dependence was not found. The porosity distributions determined by the C-14-PMMA autoradiography revealed the difference in the pore structure between the samples. The porosity of VGN consists mostly of grain boundary pores and pores between biotite lamellae. Due to a high content of nanometer scale pores anion exclusion affected the results of 36Cl and Knudsen diffusion the ones of He for VGN. Furthermore, in the PGR micrometer scale intra- and intergranular fissures form a connected network for diffusive transport and thus all tracers diffuse at the same rate.

Modeling of an in-situ diffusion experiment in granite at the Grimsel Test Site

2014 ◽  
Vol 1665 ◽  
pp. 85-91 ◽  
Author(s):  
Josep M. Soler ◽  
Jiri Landa ◽  
Vaclava Havlova ◽  
Yukio Tachi ◽  
Takanori Ebina ◽  
...  
Keyword(s):  
Effective Diffusion ◽  
Test Site ◽  
Diffusion Experiment ◽  
Bulk Rock ◽  
Disturbed Zone ◽  
Mean Grain Size ◽  
Grimsel Test Site ◽  
In Situ Diffusion

ABSTRACTMatrix diffusion is a key process for radionuclide retention in crystalline rocks. Within the LTD project (Long-Term Diffusion), an in-situ diffusion experiment in unaltered non-fractured granite was performed at the Grimsel Test Site (www.grimsel.com, Switzerland). The tracers included 3H as HTO, 22Na+, 134Cs+ and 131I- with stable I- as carrier.The dataset (except for 131I- because of complete decay) was analyzed with different diffusion-sorption models by different teams (NAGRA / IDAEA-CSIC, UJV-Rez, JAEA, Univ. Poitiers) using different codes, with the goal of obtaining effective diffusion coefficients (De) and porosity (ϕ) or rock capacity (α) values. A Borehole Disturbed Zone (BDZ), which was observed in the rock profile data for 22Na+ and 134Cs+, had to be taken into account to fit the experimental observations. The extension of the BDZ (1-2 mm) was about the same magnitude as the mean grain size of the quartz and feldspar grains.De and α values for the different tracers in the BDZ are larger than the respective values in the bulk rock. Capacity factors in the bulk rock are largest for Cs+ (strong sorption) and smallest for 3H (no sorption). However, 3H seems to display large α values in the BDZ. This phenomenon will be investigated in more detail in a second test starting in 2013.

REPRO: Through Diffusion Experiment (TDE) - Diffusion and Porosity Properties of Rock Matrix in Stress Field of Repository Level

2020 ◽  
Author(s):  
Kalle Rahkola ◽  
Antti Poteri ◽  
Lasse Koskinen ◽  
Peter Andersson ◽  
Kersti Nilsson ◽  
...  
Keyword(s):  
Stress Field ◽  
Performance Assessment ◽  
Spent Nuclear Fuel ◽  
Diffusion Experiment ◽  
Spent Fuel ◽  
Tracer Transport ◽  
Rock Matrix ◽  
Safety Case ◽  
Through Diffusion

&lt;p&gt;Radionuclides usually migrate slower than the flowing water due to sorption and matrix diffusion. The performance assessment assumes that retention takes place mostly in the vicinity of the deposition holes. REPRO (&lt;em&gt;REtention Properties of ROck matrix&lt;/em&gt;) experiments analyzed the matrix retention properties of the rock matrix under realistic conditions deep in the bedrock in ONKALO underground characterization facility at Olkiluoto, Finland. The objective was to investigate tracer transport in the rock matrix, which was representative to the near-field of the final disposal repository of the spent nuclear fuel, and to demonstrate that the assumptions made in the safety case of the deep geological spent fuel repository were in line with site evidence.&lt;/p&gt;&lt;p&gt;REPRO is composed of several supporting laboratory and &lt;em&gt;in-situ&lt;/em&gt; experiments which investigate the retention properties under different experimental configurations. The first &lt;em&gt;in-situ&lt;/em&gt; experiments were water phase diffusion experiments performed 2012-2013. Through Diffusion Experiment (TDE) studies diffusion and porosity properties of rock matrix in stress field of repository level and sorption properties of nuclides in intact rock circumstances.&lt;/p&gt;&lt;p&gt;The TDE experiment has been performed in three parallel drillholes drilled near to each other. Breakthrough of the radioactive tracer is monitored with on-line measurements and samplings along and perpendicular to the foliation. The non-sorbing radioactive isotope traces of HTO and &lt;sup&gt;36&lt;/sup&gt;Cl, as well as slightly sorbing &lt;sup&gt;22&lt;/sup&gt;Na and strongly sorbing &lt;sup&gt;133&lt;/sup&gt;Ba and &lt;sup&gt;134&lt;/sup&gt;Cs were used. TDE was designed to control advective flow, as it had caused problems in previous &lt;em&gt;in-situ&lt;/em&gt; tests.&lt;/p&gt;&lt;p&gt;Supporting laboratory studies were performed for drillcore samples sampled from the experimental drillholes. In these laboratory experiments, i.e. porosity, permeability and diffusion coefficients of the drillcores were determined using different methods.&lt;/p&gt;&lt;p&gt;The TDE experiment was carried out from 2016 to 2019. A breakthrough was seen in the timeframe predicted by scoping calculations carried out. REPRO has produced data and knowledge to the safety case and the performance assessment. According to the preliminary results, values measured in the laboratory are applicable also in larger scale and &lt;em&gt;in-situ&lt;/em&gt; conditions.&lt;/p&gt;

In-Situ Diffusion Experiment In Sparsely Fractured Granite

2004 ◽  
Vol 824 ◽  
Author(s):  
Peter Vilks ◽  
Neil H. Miller ◽  
Mark Jensen
Keyword(s):  
Field Experiments ◽  
Effective Diffusion ◽  
Rock Properties ◽  
Experimental Program ◽  
Diffusion Experiment ◽  
Stress Regime ◽  
In Situ Experiments ◽  
In Situ Diffusion ◽  
Conservative Values

AbstractThe in-situ diffusion experiment was conducted at AECL's Underground Research Laboratory (URL) to improve the understanding of diffusive solute transport in sparsely fractured or intact granitic rock (SFR). The experimental program used a comparative series of laboratory and in-situ field experiments to evaluate the ability of laboratory measurements to estimate in-situ rock properties and to explore issues surrounding the influence of stress relaxation, rock texture, porosity, pore geometry, and anisotropy on derived effective diffusion coefficients (De). In-situ experiments yielded iodide Debetween 1.4 × 10−13 and 1.1 × 10−12 m2/s. Unlike laboratory results, the in-situ De estimates did not exhibit correlation with sample depth or varied stress regime. Laboratory-derived measurements of De, porosity and permeability were found to systematically increase for samples removed from greater depths and higher stress regimes. Laboratory-derived iodide De values consistently trended higher than in-situ values by a factor of 1 to 15, except on the shallowest 240-m Level (σ1 ≍ 30 MPa) where differences were negligible. Laboratory-derived estimates of permeability were consistently higher than in-situ derived values by a factor of 2 to 100. This experimental program provides evidence that laboratory steady-state diffusion experiments are most likely to yield conservative values of De for simulation of diffusive mass transport in SFR.

Investigation of mineralogy, porosity and pore structure of Olkiluoto bedrock

2014 ◽  
Vol 1665 ◽  
pp. 31-37 ◽  
Author(s):  
Juuso Sammaljärvi ◽  
Antero Lindberg ◽  
Jussi Ikonen ◽  
Mikko Voutilainen ◽  
Marja Siitari-Kauppi ◽  
...  
Keyword(s):  
Pore Structure ◽  
Nuclear Power ◽  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Mean Value ◽  
High Porosity ◽  
Rock Matrix ◽  
Crystalline Bedrock ◽  
Rock Heterogeneity ◽  
Polarized Microscopy

ABSTRACTSpent nuclear fuel from TVO's (Teollisuuden Voima Oy) and Fortum's nuclear power plants will be deposited deep in the crystalline bedrock in Olkiluoto, Western Finland. The bedrock needs to be well characterized to assess the risks inherent to the waste disposal at the site. If radionuclides (RN) are transported, it happens via water conducting fractures. Retardation may occur either by diffusion into stagnant pore water or by immobilization on mineral surfaces of the rock matrix.RN’s retardation from flowing water is linked to parameters defining porosity and microscopic rock pore structure, such as pore size distribution, connectivity, tortuosity and constrictivity, and by the mineralogy and chemical nature of the minerals and charge of the pore surfaces.In this work, centimeter scale rock cores from Olkiluoto were investigated. The work is part of the in situ project REPRO (Experiments to investigate Rock Matrix Retention Properties) where the diffusion and sorption of RN are studied experimentally. Porosity and pore structures were characterized with the PMMA autoradiography method and polarized microscopy, which was used also to ascertain the mineralogy of the samples.The results show that the rock from the REPRO site has low porosity with a mean value of 0.5% and a range of 0.1-1.5%. Rock heterogeneity explains the variation of porosity values. Correlation between the porosity and the mineralogy was found. Areas of high porosity correspond to areas of altered minerals, such as cordierite, biotite and plagioclase, which cover spatially between 10 and 20% of the rock volume

Collecting geochemical data of deep formation fluids for Geothermal Fluid Atlas for Europe

2021 ◽  
Author(s):  
Katrin Kieling ◽  
Simona Regenspurg ◽  
Károly Kovács ◽  
Zsombor Fekete ◽  
Alberto Sánchez Miravalles ◽  
...  
Keyword(s):  
Power Plants ◽  
Field Measurements ◽  
Reservoir Rock ◽  
Geochemical Data ◽  
Geothermal Fluid ◽  
Rock Samples ◽  
Geothermal Fluids ◽  
In Situ Conditions ◽  
Fluid Properties

&lt;p&gt;Most problems in deep geothermal operations are related to the chemistry of the geothermal fluid, which might cause deleterious physical and chemical reactions such as degassing and mineral precipitation or corrosion. However, data related the fluid properties are still scarce, largely as a consequence of the difficulty in determining these properties at in situ geothermal conditions, and the fact that those data are scattered across countries and often the &amp;#8220;property&amp;#8221; of commercial operators of geothermal power plants.&lt;/p&gt;&lt;p&gt;The EU H2020 project REFLECT aims to collect existing and new data on geothermal fluids across Europe through field measurements, detailed lab experiments simulating in situ conditions, and by calculations. These data will be implemented in case-specific predictive models simulating reactions at geothermal sites, as well as in a European geothermal Fluid Atlas.&lt;/p&gt;&lt;p&gt;To harmonize the metadata information for different fluid samples, REFLECT partners plan to register IGSNs (International Geo Sample Numbers) for fluid and reservoir rock samples collected and analysed within the project. The IGSN is a unique sample identifier, i.e. it is the equivalent to a DOI for publications. It was originally developed for drill cores and extended for various sample types, including fluid samples (seawater, river or lake water, hydrothermal fluids, porewater). Registration of fluid and rock samples with an IGSN will help to allow making the data accessible and re-usable even if the fluid sample itself is destroyed.&lt;/p&gt;&lt;p&gt;All data produced and collected within REFLECT form the base of the European Geothermal Fluid Atlas, which will include query and filtering tools to explore the database with a GIS based map visualization. The Atlas makes the data accessible to the geothermal community and the general public. The aim is to create a database, which can easily be integrated into other databases, such that the Fluid Atlas can be an addition to already existing initiatives of geological data collection.&lt;/p&gt;

scholarly journals Rock Surface Fungi in Deep Continental Biosphere—Exploration of Microbial Community Formation with Subsurface In Situ Biofilm Trap

2020 ◽  
Vol 9 (1) ◽  
pp. 64
Author(s):  
Maija Nuppunen-Puputti ◽  
Riikka Kietäväinen ◽  
Lotta Purkamo ◽  
Pauliina Rajala ◽  
Merja Itävaara ◽  
...  
Keyword(s):  
Significant Proportion ◽  
Debaryomyces Hansenii ◽  
Fungal Communities ◽  
Fungal Colonization ◽  
Rock Surface ◽  
Mica Schist ◽  
Deep Subsurface ◽  
Bacterial Phyla ◽  
In Situ Conditions

Fungi have an important role in nutrient cycling in most ecosystems on Earth, yet their ecology and functionality in deep continental subsurface remain unknown. Here, we report the first observations of active fungal colonization of mica schist in the deep continental biosphere and the ability of deep subsurface fungi to attach to rock surfaces under in situ conditions in groundwater at 500 and 967 m depth in Precambrian bedrock. We present an in situ subsurface biofilm trap, designed to reveal sessile microbial communities on rock surface in deep continental groundwater, using Outokumpu Deep Drill Hole, in eastern Finland, as a test site. The observed fungal phyla in Outokumpu subsurface were Basidiomycota, Ascomycota, and Mortierellomycota. In addition, significant proportion of the community represented unclassified Fungi. Sessile fungal communities on mica schist surfaces differed from the planktic fungal communities. The main bacterial phyla were Firmicutes, Proteobacteria, and Actinobacteriota. Biofilm formation on rock surfaces is a slow process and our results indicate that fungal and bacterial communities dominate the early surface attachment process, when pristine mineral surfaces are exposed to deep subsurface ecosystems. Various fungi showed statistically significant cross-kingdom correlation with both thiosulfate and sulfate reducing bacteria, e.g., SRB2 with fungi Debaryomyces hansenii.

scholarly journals From small wrinkles to Schallamach waves during rubber friction: In situ experiment and 3D simulation

2021 ◽  
Vol 96 ◽  
pp. 107084
Author(s):  
Cui Zhibo ◽  
Su Zhaoqian ◽  
Hou Dandan ◽  
Li Genzong ◽  
Wu Jian ◽  
...  
Keyword(s):  
3D Simulation ◽  
In Situ Experiment ◽  
Rubber Friction
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