GI5.4

Underground laboratories, test-sites and their networks

GI5.4

Underground laboratories, test-sites and their networks

Convener: Marcus Laaksoharju | Co-conveners: Jari JoutsenvaaraECSECS, Vera LayECSECS

vPICO presentations

| Fri, 30 Apr, 11:45–12:30 (CEST)

Public information:

What are underground laboratory and geological test-sites? Why they are important in highlighting the importance of geoscientific site understanding as a research and innovation driver? Come and join our session discussions.
The session is chaired by Marcus Laaksoharju.

vPICO presentations: Fri, 30 Apr

Chairpersons: Marcus Laaksoharju, Jari Joutsenvaara, Vera Lay

11:45–11:50

5-minute convener introduction

11:50–11:52

EGU21-9398

Highlight

Global networks of underground research – Geoinformatics in exploring the interaction between laboratories and research units by geocoded publication metadata

Ossi Kotavaara, Jari Joutsenvaara, Julia Puputti, Eija-Riitta Niinikoski, Ursula Heinikoski, and Pertti Martinmäki

Globally there are more than 75 identified scientific underground facilities or laboratories. Underground laboratories or underground research mines are related to 400.000 scientific publications in the Web of Science since 1975. Underground laboratories are commonly located in operational or closed mines, tunnel systems, or built for this specific purpose. It is clear that a wide variety of disciplines and research units apply these facilities. However, it is unclear what is the thematic distribution in research by laboratories at a global scale, or what is the geographic distribution of the scientific communities applying the facilities? In practice, do, e.g. political borders or distance play a role in this?

Understanding prevailing and potential market areas of underground laboratories and research mines for research communities applying these facilities are key elements in developing the use and utilisation of such facilities. Again, it is important to get a better knowledge of the structures, networks, and thematic emphasise of these research communities to understand their requirements and expectations for the underground research infrastructures. This study aims to deepen the knowledge in this field by geocoding teams and units published research, which applied underground facilities. Geographic information systems (GIS) and geocoding functions are applied to build a network between underground laboratories and research teams using all recognised underground research from the web of knowledge. Preliminary analysis indicates that underground laboratories may have a large global scientific user network, but the relatively active network of a few key partner institutes.

The research is supported by the Interreg Baltic Sea programme funded Empowering Underground Laboratories network usage – EUL and the Baltic Sea Underground Innovation Network (BSUIN) projects.

How to cite: Kotavaara, O., Joutsenvaara, J., Puputti, J., Niinikoski, E.-R., Heinikoski, U., and Martinmäki, P.: Global networks of underground research – Geoinformatics in exploring the interaction between laboratories and research units by geocoded publication metadata, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9398, https://doi.org/10.5194/egusphere-egu21-9398, 2021.

11:52–11:54

EGU21-14791

Empowering Underground Laboratories Network Usage in the Baltic Sea Region

Eija-Riitta Niinikoski and the team

In the Baltic Sea region, there are world leading science organisations and industrial companies specialised in geophysics, geology and underground construction. There are also several highly interesting underground laboratories (ULs), research mines and test-sites, that are not utilised to their full potential.

Six of these facilities cooperate within the Interreg Baltic Sea Region program funded project, Empowering Underground Laboratories Network Usage (EUL) [1]. Underground facilities have been established into existing or historical mines, research tunnel networks or as a dedicated underground laboratory for a specific purpose. The EUL project continues in 2021 the work of the Interreg funded Baltic Sea Underground Innovation Network (BSUIN) [2], that ended in December 2020. While the BSUIN project concentrated on characterising the underground facilities and operational settings, the EUL project works on testing, validation, and enhancing previously created practices, tools, and approaches. During the EUL project, the emphasis is put on identifying the global user segments of underground facilities, the effectiveness of marketing of ULs and created network, now known as European Underground Laboratories Association, and customer relations management from the first contact to the realisation of the project.

The underground laboratories participating in BSUIN and EUL projects are Callio Lab (Pyhäjärvi Finland), ÄSPÖ Hard Rock Laboratory (Oskarshamn, Sweden), Ruskela Mining Park (Ruskeala, Russia), Educational and research mine Reiche Zeche (Freiberg, Germany), Underground Low Background Laboratory of the Khlopin Radium Institute (St.Petersburg, Russia) and the Conceptual Lab development co-ordinated by KGHM Cuprum R&D centre (Poland).

One of the main objectives of EUL project is to test the developed business and service concepts for the established network of underground laboratories and for the individual laboratories. Testing ensures the functionality of laboratory service concepts and customer relationship management processes for commercial and non-commercial users.

Another main objective is to test and develop the web-based tool (WBT). Users from partner and associative organisations and underground laboratories (Uls) will test it from their perspectives. The feedback helps to steer the tool into the more user-friendly and more purposeful direction for the potential customers and the underground laboratory managers to use.

To reach new customers and understand different possible customer segments, a big data analysis of users of ULs world-wide will be conducted. Also marketing the network and underground laboratories will be tested and best marketing strategies identified.

Main target groups are the ULs, their users and potential customers (companies and researchers). Another target group is regional development agencies that will be informed about the business possibilities in ULs so that they can provide information to potential customers looking for business opportunities.

In this paper, the EUL project's first outcomes will be discussed reflected to the BSUIN project. The BSUIN and EUL projects are funded by the Interreg Baltic Sea Region Progamme.

[1] Empowering Underground Laboratories Network Usage, www.bsuin.eu, 18 Jan 2021

[2] Baltic Sea Underground Innovation Network, www.bsuin.eu, 18 Jan 2021

How to cite: Niinikoski, E.-R. and the team: Empowering Underground Laboratories Network Usage in the Baltic Sea Region, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14791, https://doi.org/10.5194/egusphere-egu21-14791, 2021.

11:54–11:56

EGU21-14229

ECS

Highlight

From Earth and beyond – Callio Lab underground centre for Science and R&D

Julia Puputti, Jari Joutsenvaara, Ossi Kotavaara, and Eija-Riitta Niinikoski

Callio Lab is a unique research infrastructure operating at the Pyhäsalmi Mine in Finland [1]. It is coordinated by the University of Oulu Kerttu Saalasti Institute (KSI) [2]. Callio Lab is a key component of the larger CALLIO -Mine for Business concept aiming at repurposing the mine area into an economically feasible multidisciplinary operating environment [3]. Underground mining ends in autumn 2021 after which CALLIO continues to host activities at the mine-site until at least 2025.

Callio Lab has provided unique environments for fields of research ranging from physics and geosciences to underground food production and construction. As of spring 2021, Callio Lab has served as the host site for numerous international projects such as MINETRAIN, Goldeneye, and BSUIN. The MINETRAIN project developed intensive training courses for mining professionals through a holistic approach to the mine lifecycle [4]. Goldeneye is creating an artificial intelligence platform to improve safety, efficiency and profitability of mine sites in Europe [5]. BSUIN was headed by KSI and it piloted a method of thorough geophysical, structural, organizational and natural background radiation (NBR) characterization, making underground laboratories (UL’s) more accessible for new and current users [6]. Opportunities in the fields of plant-based mineral exploration, geopolymers, circular economy, muography research as well as fire and blasting test sites are also being explored. Launched in 2018, the Callio SPACELAB initiative is dedicated to studies in space and planetary sciences. [1]

We have detailed knowledge of the overall geological structures, rock mechanics, and characteristics of the Callio Lab underground environments. This is due to the characterization activities performed during the BSUIN project, collected data materials from previous research, and the extensive microseismic network. Understanding the characteristics of the UL’s is key in understanding the possibilities for R&D and science. [1,6]

Callio Lab currently houses seven underground laboratories at different depths ranging from a shallow 75 meters underground all the way to the Main level and bottom of the mine at 1440 meters. There are two routes of access via the incline tunnel or the elevator shaft. The operating environment has good existing infrastructure and facilities, including electrical workshops, maintenance halls, a restaurant, offices, secure high-speed internet access, a logistically ideal single location, as well as the ability to provide innovation support and managing processes. In-depth understanding of underground risk management and the conditions of the working environment make Callio Lab a safe operating environment with vast opportunities and potential to grow into an internationally recognized research institute. [1]

[1] Callio Lab – Underground Center for Science and R & D, www.calliolab.com, 8 Jan 2021

[2] Kerttu Saalasti Institute, www.oulu.fi/ksi-eng, 8 Jan 2021

[3] Mine for Business – Callio – Pyhäjärvi, Finland , www.callio.info, 8 Jan 2021

[4] MINETRAIN, www.minetrain.eu, 8 Jan 2021

[5] GoldenEye EU H2020 funded project, www.goldeneye-project.eu, 8 Jan 2021

[6] Baltic Sea Underground Innovation Network, www.bsuin.eu, 8 Jan 2021

How to cite: Puputti, J., Joutsenvaara, J., Kotavaara, O., and Niinikoski, E.-R.: From Earth and beyond – Callio Lab underground centre for Science and R&D, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14229, https://doi.org/10.5194/egusphere-egu21-14229, 2021.

11:56–11:58

EGU21-14230

ECS

Advancing Scientific Research and Education at the FLB Reiche Zeche underground mine in Freiberg - Germany

Jose Garcia-del-Real, Toni Müller, Helmut Mischo, Vera Lay, and Stefan Buske

The shaft at Reiche Zeche mine provides direct access to the research and training underground mine of the reputed TU Bergakademie Freiberg, where advanced scientific research and practical education is executed for more than 100 years now.

Since 1919, the former ore mine is used for educating and training of miners, engineers and mine surveyors by the TU Bergakademie Freiberg. Drifts and tunnels of the mine stretch over several kilometres at depths down to 230 m. Today, the Reiche Zeche mine plays a major role in mining research and related activities including various research institutes and industrial partners. Several underground test facilities and laboratories are in use and play a key role in university education. A variety of local (15 institutes of TU Bergakademie Freiberg) and external partners (30 from 26 countries) are actively shaping research and education in the mine.

Real-world applications and cutting-edge technologies are tested in a stimulating environment underground, helping to improve competitiveness, leadership, creativity and critical thinking of researchers, companies and stakeholders.

Most recent research projects provide innovative solutions in way different fields. Robotics, smart mining, geophysical monitoring, a blasting chamber used for material science research, and also new mining technologies such as biohydrometallurgical mining for the winning of metals from ores, tailings and recycling material are only a small sample of the Reiche Zeche´s advanced innovation areas.

At Reiche Zeche mine, an efficient research and innovation environment is provided. It includes high quality underground spaces, cutting-edge methodology, state-of-the art labs, high-quality staff, resources and services to industries, talented individuals, leading researchers and teams from six continents, who truly want to make a real positive difference in the Society, contributing therefore, to sustainable optimisation for the raw materials value chain.

We are actively contributing to the European Underground Laboratories (EUL) network, forming an efficient platform for future, innovative research and business activities in underground laboratories. We are always open for collaboration with interested researchers and related stakeholders.

How to cite: Garcia-del-Real, J., Müller, T., Mischo, H., Lay, V., and Buske, S.: Advancing Scientific Research and Education at the FLB Reiche Zeche underground mine in Freiberg - Germany, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14230, https://doi.org/10.5194/egusphere-egu21-14230, 2021.

11:58–12:00

EGU21-14977

Geological & information model of underground space as a museum object: the Rogoselga mine case (Russian Federation, Karelia)

Vitali Shekov, Kirill Shekov, and Svetlana Krylova

In addition to mining, underground space is widely used for various purposes - tunnels, underground storage facilities, etc. Very often, such structures are built specifically taking into account their use, less often they use the developed space. At the same time, the museum space is perceived "as is."

The main difference between the museum mining space and other uses of mining is the conflict between the maximum preservation of the interiors of these workings (it should be authentic, that is, to contain previously used in this space technological, historical, cultural content) and safe, i.e., the geotechnical state should correspond to the safe stay of visitors. That is why the study of the sustainability of mining is becoming the number one task in such studies. The problem is compounded for abandoned mining operations, the operation of which was discontinued many years ago.

Some solutions were proposed during the study of the abandoned Rogoselga mine, located near a high-traffic highway 135 km from the city of Petrozavodsk, 4 km from the village of Kolatselga, Republic of Karelia, Russian Federation.

Underground production appeared in the process of hematite extraction, as the main raw material for the local ironworks in 1898. Mining was stopped in 1903 and, after several attempts to restore, was closed. This complex of workings is a valuable monument to the whole era of iron ore production in the southeastern part of the Fenno-Scandinavian Shield, in terms of historical and cultural points of view.

The underground space includes the remnants of preparatory rollbacks, as well as the remnants of the wasting chambers, the ore of which went by itself in the rollbacks and then on the gallery was delivered to the surface. The total length of the workings does not exceed 300 meters, with a diameter of 2 meters, and the thickness of the ore body in the chambers up to 3 meters.

Over more than a century, the underground area has been slightly transformed by the collapses of individual parts but has retained but some areas are in good condition. To evaluate the workings, some methods for assessing the underground space were proposed, including modern approaches to documenting the workings, assessing the sustainability of the vault, and individual preparatory works. The result is the development of a geological and information model of the underground space, allowing to study stability by modern methods, including the finite elements method (FEM).

The small size of the work predetermined the methods used. The methodology used in photogrammetry has been adopted as a general technology of 3D modeling.

The work has led to the development of several solutions for small-diameter imaging and lighting technology, as well as to identify "weaknesses" in production and the possibility of using geotechnical techniques to assess the stability of the array.

How to cite: Shekov, V., Shekov, K., and Krylova, S.: Geological & information model of underground space as a museum object: the Rogoselga mine case (Russian Federation, Karelia), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14977, https://doi.org/10.5194/egusphere-egu21-14977, 2021.

12:00–12:02

EGU21-16523

Underground heritage valorization of camerano's cave in center italy a case of transition towards projects integrating the local community and landscape

Roberto Pierdicca, Eva Savina Malinverni, Francesco di Stefano, Giuseppe Pace, Ilaria Fioretti, Andrea Galli, Ernesto Marcheggiani, and Francesco Paci

Underground4Value is a COST Action (CA18110) aiming at providing adequate cultural, scientific and technical knowledge of the UBH concerning different aspects (i.e. archaeology, geotechnics, history, urban planning, architecture, cultural anthropology, economics, tourism, sustainable development), in a multi-disciplinary context. So far there are 30 participant countries, moreover Tunisia and Mexico.

The overarching idea is supporting Underground Built Heritage (UBH) conservation, valorization, management, and fostering decision-making through community-led development. The main challenge is how to stimulate social innovations in local communities through heritage management approaches.

One of the living lab stemmed by the activities of the Cost Action is in center Italy, where are many other hypogea with different function: water reservoir, military-strategic, food storage, cultural or religious function, mines or quarries. Among them the city of Camerano represents a local heritage and a landmark for its network of connected built underground spaces. The local community's self-initiative and the determination and far-sightedness of the local authority allowed to differentiate the local tourism offer leading to success in terms of tourism attractiveness, with more than 25'000 visitors per year. First reliable records date 1327 AC.

Special attention is given to the digital dimension of Cultural Heritage. An asset for the next decade, in particular after the COVID-19 pandemic. Surveys of the interior environment of the caves were carried out using two laser instruments in different acquisition modes. The use of the static laser scanner requires a longer time for both the acquisition and the subsequent processing phases. The use of a mobile laser scanner, on the other hand, makes it possible to scan and record the underground environment in real time in just a few hours, thus providing a fast and agile solution. This means that it is possible to go more often for constant and rapid monitoring. The integration of spherical photos taken along the route of the caves themselves offers the possibility of creating a virtual reality (VR) tour that can be integrated with a 3D model of the entire underground environment. This allows the caves to be visited from a virtual point of view when they are closed for restoration work or in cases of emergencies, such as pandemic one.

How to cite: Pierdicca, R., Malinverni, E. S., di Stefano, F., Pace, G., Fioretti, I., Galli, A., Marcheggiani, E., and Paci, F.: Underground heritage valorization of camerano's cave in center italy a case of transition towards projects integrating the local community and landscape, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16523, https://doi.org/10.5194/egusphere-egu21-16523, 2021.

12:02–12:04

EGU21-7000

Highlight

A geoscientific site descriptive model for the Äspö Hard Rock Laboratory, SE Sweden

Jesper Petersson, Peter Hultgren, Mansueto Morosini, and Frédéric Mathurin

The development of an updated geoscientific site descriptive model (SDM) is currently in progress for the Äspö Hard Rock Laboratory (Äspö HRL), the key underground research facility of the Swedish Nuclear Fuel and Waste Management Company (SKB). Äspö HRL is located in south-eastern Sweden, within a suite of 1.81–1.76 Ga granitoids, and consists of a tunnel system down to 460 m depth with a total length of about 5 km. Tectonically, the area is part of a contractional shear belt, primarily manifested by a NE-SW trending regional deformation zone, which partly transect the underground facility. The shear zone system has evolved gradually over a prolonged period, with an initial low-grade ductile development, followed by multiple events of brittle reactivation. The structural framework is characterised by a signiﬁcant heterogeneity in the hydraulic ﬂow properties, where the most transmissive structures belong to a set of less extensive, conjugate zones and fractures.

More than 30 years of studies, starting with the pre-investigations and construction of the facility, have generated a wealth of geoscientific data in 3-D space, and hence a sound basis for an update of existing models. The SDM under current development aims to present an integrated geoscientific understanding of the Äspö site, with special focus on geology, hydrogeology and hydrogeochemistry. The general working procedure includes basically an initial stage of data capture, followed by an intermediate interpretative stage, and finally the construction of 3-D models with associated concepts and parameters. An explicit goal throughout the work has been to encourage interaction between the different geo-disciplines, especially during the interpretative stage, as a forerunner to the final stage of deterministic/conceptual modelling. During the interpretative stage, geological and geophysical information were combined into two basic building blocks along individual boreholes, tunnels, and outcrops: rock units and possible deformation zones, which were assigned hydraulic parameters such as primarily K-values. The subsequent geological 3-D modelling comprises two components: rock domains and deformation zones with a surface trace length of ≥ 300 m. Hydrogeological feedback was provided in terms of K-anisotropies and depth trends.

The fundamental outcome of the modelling is a more profound conceptual understanding, along with geometries and properties for each domain or zone. Additional outcomes are data on and understanding of the effects of 25 years of artificial tunnel drainage on groundwater pressures, flow and chemistry. The natural groundwater system, originally formed by paleoclimatic and geological factors over a vast period, has be profoundly influenced by important monitored phenomena. Upflow of deep-lying saline water and extensive intrusion of current seawater disclose the apparent hydro-properties and interconnection between deformation zones.

Currently, geological 3-D model includes geometries for ten rock domains and 24 deformation zones, the latter with seamless transitions to zones of the regional scale Laxemar model, as developed by the SKB with the objective of siting a geological repository for spent nuclear fuel in the proximity to the Äspö HRL. As completed, the models will serve as framework for more detailed-scaled facility models.

How to cite: Petersson, J., Hultgren, P., Morosini, M., and Mathurin, F.: A geoscientific site descriptive model for the Äspö Hard Rock Laboratory, SE Sweden, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7000, https://doi.org/10.5194/egusphere-egu21-7000, 2021.

12:04–12:06

EGU21-7682

ECS

Finite Element Method-based geomechanical risk assessment of underground laboratory located in the deep copper mine

Krzysztof Fulawka, Witold Pytel, Piotr Mertuszka, and Marcin Szumny

Underground laboratories provide a unique environment for various industries and are a suitable place for developing new technologies for mining, geophysical surveys, radiation detection, as well as many other studies and measurements. Unfortunately, any operation in underground excavations is associated with exposure to many hazards not necessarily encountered in surface laboratories. One of the most dangerous events observed in underground conditions is the dynamic manifestation of rock mass pressure in form of rockburst, roof falls and mining tremors. Therefore, proper evaluation of geomechanical risk is a key element ensuring the safety of work in underground conditions. Finite Element Method-based numerical analysis is one of the tools which allow conducting a detailed geomechanical hazard assessment already at the object design stage. The results of such calculations may be the basis for the implementation of preventive measures before running up the underground facility.

Within this paper, the three-dimensional FEM-based numerical analysis of large-scale underground laboratory located in deep Polish copper mine was presented. The calculations were made with GTS NX software, which allowed determining the changes in the safety factor in surrounding of the analyzed area. Finally, the possibility of underground laboratory establishment, with respect to predicted stress and strain conditions, were determined.

How to cite: Fulawka, K., Pytel, W., Mertuszka, P., and Szumny, M.: Finite Element Method-based geomechanical risk assessment of underground laboratory located in the deep copper mine, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7682, https://doi.org/10.5194/egusphere-egu21-7682, 2021.

12:06–12:08

EGU21-700

ECS

3D Predictive HM-modeling in the heterogeneous Opalinus Clay of the Mont Terri rock laboratory and validation with monitoring data from a mine-by test

Chao Li, David Jaeggi, Christophe Nussbaum, and Paul Bossart

The Mont Terri rock laboratory began in 1996 with 8 niches, followed by a research tunnel in 1998. Since then the laboratory has been expanded every 10 years, mainly in the shaly facies of the Opalinus Clay. In March 2018, south of the existing laboratory, the Mont Terri Project Partners initiated another extension «Gallery 18» of the Mont Terri rock laboratory mainly located in sandy facies of the Opalinus Clay. In October 2019 the extension was finished, resulting in more than 500 m of additional galleries and niches for new experiments. In the frame of this extension, for the first time a heterogeneous mine-by test, comprising a sheet of sandy facies and carbonate-rich sandy facies sandwiched between shaly facies was conducted in the rock laboratory. This so-called MB-A experiment (hydro-mechanical characterization of the sandy facies before and during excavation) consists of two lateral niches for instrumentation and monitoring and a test gallery of 30 m length oriented perpendicular to the latter. The instrumentation based on 26 boreholes with lengths up to 40 m consists of pore pressure transducers, extensometers, inclinometers and stress monitoring stations. It was finished several months before excavation of the test section was started in order to assure equilibration close to the initial conditions. Excavation of the test gallery running parallel to bedding strike was carried out in May 2019 in 20 days.

Elastic predictive modeling is performed in 3D to estimate the hydro-mechanical behavior of the rock mass during a sequential excavation according to effective daily advances and as-is sensor locations. The modeling results are compared with monitoring data. The calculation predicts a rotation of the early time near-field pore pressure reduction from perpendicular to parallel to bedding for late times. In general, monitored peak pore water pressures were higher than predicted, with a remarkable phase shift depending on distance and spatial position with respect to the drift. Monitored deformations were clearly underestimated with the elastic calculation. The overall behavior of the excavation in the sandy facies was unexpectedly not so different from former excavations in shaly facies.

A parametric study was performed to assess key parameters of potential effects of excavation on the hydromechanical responses of the excavation. It is concluded that adapted constitutive laws are needed in order to properly predict the hydromechanical response in stiffer claystone, such as for instance the sandy and carbonate-rich sandy facies of the Opalinus Clay.

How to cite: Li, C., Jaeggi, D., Nussbaum, C., and Bossart, P.: 3D Predictive HM-modeling in the heterogeneous Opalinus Clay of the Mont Terri rock laboratory and validation with monitoring data from a mine-by test, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-700, https://doi.org/10.5194/egusphere-egu21-700, 2021.

12:08–12:10

EGU21-898

Hydrogen gas bubble nucleation from corrosion of steel in compacted bentonite

Alexandros Papafotiou, Chao Li, Nikitas Diomidis, and Olivier Leupin

The reference concept for the deep geological disposal of spent fuel and high-level radioactive waste in Switzerland foresees carbon steel disposal canisters surrounded by compacted bentonite buffer material. In support of performance assessments, long-term in-situ corrosion experiments were conducted in Opalinus Clay at the Mont Terri Underground Research Laboratory (URL) in Switzerland, wherein carbon steel coupons were embedded in MX-80 bentonite. The preparation of the steel specimens and bentonite, the exposure in a sealed borehole in the URL, and the retrieval, dismantling and imaging of specimens were conducted under strictly anoxic conditions. Samples were removed for analysis after exposure durations of 372, 628, 1024, and 2008 days. A key finding was the development of visible reddish-brown corrosion fronts around the metal surfaces and along shrinkage cracks that extend up to approximately 0.5 cm into the bentonite. Iron that originated from the corroded surface was transported along the cracks and precipitated as Fe-hydroxides due to oxygen sorbed on bentonite.

The formation of shrinkage cracks is thought to result from a local desaturation of the bentonite near the steel surface. To test this hypothesis i.e., to test the likelihood of a separate gas phase forming in addition to hydrogen mass dissolved in liquid water, it is necessary to evaluate the fate of hydrogen in the bentonite adjacent to the steel surface. For this, a flow and transport numerical model of the steel coupon surface and surrounding bentonite was implemented for the simulation of hydrogen release with the simultaneous consumption of water at the steel surface. The effect of single- and (potentially) two-phase flow with the diffusive and advective transport of the hydrogen and water components in the gas and liquid phases were modelled in a fully coupled manner. The numerical simulations were performed probabilistically in a Monte Carlo framework to account for parametric uncertainty, comprising 1’000 perturbations of all flow and transport parameters used in the model for the bentonite.

Overall, the simulation results are consistent with the hypothesis of a link between cracks observed in the bentonite and a temporary formation of a gas phase that results in preferential pathways for the transport of iron corrosion products. The probability of gas formation in the model lies between 89% and 94% at the steel-bentonite interface and decreases significantly at distance of 1 cm from the steel coupon. Peak gas saturation at the steel-bentonite interface ranges up to approximately 1% with a mean value of approximately 0.18%. In all simulations, any gas phase forming in the bentonite dissolves back into the liquid phase within 300 days.

How to cite: Papafotiou, A., Li, C., Diomidis, N., and Leupin, O.: Hydrogen gas bubble nucleation from corrosion of steel in compacted bentonite, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-898, https://doi.org/10.5194/egusphere-egu21-898, 2021.

12:10–12:12

EGU21-2024

Natural Gamma-Ray Background Characterization in Pyhasalmi Mine

Vladimir Gostilo, Serhii Pohuliai, Alexander Sokolov, Jari Joutsenvaara, and Julia Puputti

We present the results of measuring the gamma-ray background performance of Pyhasalmi mine, the deepest one in Europe. Two underground facilities in Lab 2 (1440 m) and Lab 5 (1410 m) were investigated. Based on measurements made in Lab 2 with a low-background HPGe spectrometer, we determined the integral gamma-ray background count rate in the energy range of 40 keV to 2.7 MeV to be 0.095 s^–1 kg^–1. The minimum detectable activities of some natural and artificial nuclides were less than 0.071 Bq/kg (²²⁶Ra), 0.77 Bq/kg (⁴⁰K) and 0.012 Bq/kg (¹³⁷Cs). The specific activities of natural nuclides in the shotcrete covering the walls of the Lab 2 were higher than those in the rock: 100.3 Bq/kg (²³²Th), 161.7 Bq/kg (²²⁶Ra) and 1171 Bq/kg (⁴⁰K) in the shotcrete covering and 47.6 Bq/kg (²³²Th), 83.1 Bq/kg (²²⁶Ra) and 1513 Bq/kg (⁴⁰K) in the rock. The measurements showed that the gamma-ray background level in Lab 5 is significantly lower than that in Lab 2. The integrated gamma-ray background count rate for the energy range of 40 keV to 2.7 MeV was 0.028 s^–1 kg^–1 for Lab 5. Purging the measuring chamber of the gamma spectrometer with nitrogen gas at a rate of 0.15 L/h allowed to further improve this parameter to 0.021 s^–1 kg^–1. In general, the results of this study confirm that the level and energy spectrum of background gamma radiation in the underground facility within the studied energy range is defined mainly by the composition of the walls of the Labs.

How to cite: Gostilo, V., Pohuliai, S., Sokolov, A., Joutsenvaara, J., and Puputti, J.: Natural Gamma-Ray Background Characterization in Pyhasalmi Mine, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2024, https://doi.org/10.5194/egusphere-egu21-2024, 2021.

12:12–12:30

Meet the authors in their breakout text chats