scholarly journals Sub-areas in steep rock salt formations – what do we know about the geological composition of North German salt structures?

2021 ◽  
Vol 1 ◽  
pp. 73-74
Author(s):  
Lukas Pollok ◽  
Mareike Henneberg
Keyword(s):  
Internal Structure ◽  
Rock Salt ◽  
Site Selection ◽  
Selection Process ◽  
Detailed Knowledge ◽  
Suitable Host ◽  
Geological Conditions ◽  
Salt Structure ◽  
Host Rocks

Abstract. Suitable host rocks for a repository for high-level radioactive waste (HLW) in Germany include not only clay and crystalline rocks but also rock salt formations in so-called flat and steep bedding (StandAG, 2017). Favourable repository relevant properties of rock salt are, e.g. the high heat conductivity, low porosity and permeability, and its viscoplastic deformation behaviour. Thicker salt deposits can be attributed to the formation of approx. 700 salt structures that have formed under various geological conditions in the North German Basin (NGB) over the last 250 million years. According to their shape and genesis, salt structures are classified as salt pillows (considered as flat bedding) or salt diapirs (steep bedding). Out of a total of 74 sub-areas in rock salt, 60 sub-areas in salt diapirs consisting of Permian evaporates were identified within the first phase of the German site selection procedure (BGE, 2020). At the current stage of the site selection process, a conservative approach has been adopted and the internal structure of the salt structures have not yet been taken into account for further classification of the identified sub-areas. However, the interior of the salt structures not only consists of rock salt but also of varying proportions of clay, carbonate and anhydrite rocks, as well as potassium salts formed by progressive evaporation of marine brines. Multi-phase salt tectonics has led to the folding of these differently composed layers and to complex internal structures. Therefore, detailed knowledge of the salt structure compositions is necessary to identify suitable rock salt areas for the designation of the containment providing rock zone. As a result of decades of research through extensive salt and potash mining, cavern storage and exploration for final waste disposal, Permian salt rocks represent a well-studied host rock in Germany. The use of different exploration methods and multidisciplinary data evaluation have led to a comprehensive understanding of the internal composition of some well-studied salt structures. Systematic studies have shown that several factors have influenced the formation of salt structures as well as their external shapes, sizes, and spatial distribution (e.g., Pollok et al., 2020). Furthermore, the amount and distribution of suitable host rocks varies greatly in different salt structures and is closely related to their internal structure. Since the interior of salt structures has not been considered in the site selection process so far, a classification of salt structures (or sub-areas) into certain types with varying internal composition and complexity is presented. By examining their lithofacial composition, genesis, and structural geological position within the basin, it is possible to narrow down these types to specific areas in the NGB. Without the acquisition of additional exploration data in this phase of the site selection process, this salt structure classification provides important data for the legally demanded assessment of the overall favourable geological situation.

Which Processes could define Temperature Limits on the Outer Surface of a Container in a Disposal Facility ?

2020 ◽  
Author(s):  
Guido Bracke ◽  
Eva Hartwig-Thurat ◽  
Jürgen Larue ◽  
Artur Meleshyn ◽  
Torben Weyand ◽  
...  
Keyword(s):  
Outer Surface ◽  
Site Selection ◽  
Selection Process ◽  
Temperature Limit ◽  
Crystalline Rock ◽  
Safety Concept ◽  
Disposal Facility ◽  
High Level ◽  
A Site ◽  
Host Rocks

<p>When the recommencement of the search for and selection of a site for a disposal facility for HLRW in Germany was stipulated by the Site Selection Act (StandAG 2017) in 2017, a <strong>precautionary </strong>temperature limit of 100 °C on the outer surface of the containers with high-level radioactive waste in the disposal facility section was set. This <strong>precautionary </strong>temperature limit shall be applied in preliminary safety analyses provided that the “maximum physically possible temperatures” in the respective host rocks have not yet been determined due to pending research. Therefore, this issue is addressed and discussed in this paper, contributing to “pending research” by a review of the literature.</p><p>This presentation briefly discusses a few examples of thermohydraulical, mechanical, chemical and biological processes in a disposal facility, because temperature limits are derived based on safety impacts regarding THMCB-processes. The temperature-dependent processes have been extracted from databases for features, events and processes (FEP-databases). Furthermore, it is dicussed if the feasibility to retrieve and recover HLRW is hampered at high temperatures.</p><p>It is concluded that a design temperature concerning single components of a disposal facility for the preservation of their features can be derived when a safety concept is established. However, the interactions of all relevant processes in a disposal concept must be considered to determine a specific temperature limit for the outer surface of the containers. Therefore, applicable temperature limits may vary for particular safety and disposal concepts in the following host rocks: rock salt, clay stone and crystalline rock.</p><p>Technical solutions for retrieval and design options for recovery seem to be viable up to temperatures of 200 °C with different, sometimes severe, downsides according to expert judgement.</p><p>It is summarized that emperature limits regarding the outer surface of the containers can be derived specifically for each safety concept and design of the disposal facility in a host rock. General temperature limits without reference to specific safety concepts or the particular design of the disposal facility may narrow down the possibilities for optimisation of the disposal facility and could adversely affect the site selection process in finding the best suitable site.</p>

scholarly journals Mineral stability, brine development and rock-fluid reaction at repository-relevant temperatures (<i>T</i> < 200 °C) in the potential host rock rock salt

2021 ◽  
Vol 1 ◽  
pp. 101-102
Author(s):  
Michael Mertineit ◽  
Michael Schramm
Keyword(s):  
Melting Point ◽  
Rock Salt ◽  
Site Selection ◽  
Host Rock ◽  
Mineralogical Composition ◽  
Confining Pressure ◽  
Maximum Temperature ◽  
General Importance ◽  
Host Rocks ◽  
The Impact

Abstract. For a repository of heat generating radioactive waste, the thermal behaviour of the host rock and the impact of temperature increase on rock properties is of general importance. In the German Site Selection Act (2017), the maximum temperature of the container surface is preliminarily limited to 100 ∘C but this limit might change in the future based on scientific and technological findings. Rock salt, as one of the possible host rocks, consists predominantly of halite with varying amounts of accessory minerals (e.g., Hudec and Jackson, 2007); however, some lithological units within a salt deposit, e.g. potash seams, show a different mineralogical composition with high amounts of potash minerals. Most of them are not very stable regarding temperature resistance and stress, contain water in the crystal lattice, and therefore react sensitively to changes in the environment. The melting point of most evaporated minerals is higher than the expected temperatures in a repository but dehydration and partial melting might occur at relevant temperatures, depending on the confining pressure. For example, the temperature of dehydration of carnallite is ca. 80 ∘C at 0.1 MPa confining pressure but increases to ca. 145 ∘C at 10 MPa confining pressure (Kern and Franke, 1986). The melting point of carnallite increases from ca. 145∘C/8MPa to ca. 167∘C/24MPa, which corresponds to a depth of ca. 1000 m. Depending on the mineral paragenesis and composition of saline solutions, different minerals develop with increasing temperature. For instance, a salt rock with an initial composition of kieserite + kainite + carnallite + solution R (25 ∘C) reacts solely to kieserite and solution R, when the temperature increases to 78 ∘C. A rock with a composition of kieserite + carnallite + bischofite + solution Z (25 ∘C) reacts to kieserite + carnallite from 25 to 50 ∘C, from 50 to 73 ∘C only kieserite is stable, and at temperatures >73 ∘C kieserite and bischofite develop (Usdowski and Dietzel, 1998). For the construction of an underground repository, the mineralogical composition of the host rocks and fluids have to be evaluated carefully and play an important role for the site selection and design of the underground facility.

scholarly journals Towards best possible safety – current regulatory research for the German site selection process for high-level radioactive waste disposal

2020 ◽  
Vol 54 ◽  
pp. 157-163
Author(s):  
Axel Liebscher ◽  
Christoph Borkel ◽  
Michael Jendras ◽  
Ute Maurer-Rurack ◽  
Carsten Rücker
Keyword(s):  
Radioactive Waste ◽  
Nuclear Waste ◽  
Waste Disposal ◽  
Rock Salt ◽  
Site Selection ◽  
State Of The Art ◽  
Selection Process ◽  
Fault Zones ◽  
Radioactive Waste Disposal ◽  
Methodological Approaches

Abstract. The Federal Office for the Safety of Nuclear Waste Management (BASE – Bundesamt für die Sicherheit der nuklearen Entsorgung) is the German federal regulatory authority for radioactive waste disposal. It supervises the German site selection process and is responsible for the accompanying public participation. Task related research is an integral part of BASE's activities. The projects MessEr and übErStand compiled the state-of-the-art science and technology regarding surface based exploration methods suitable for addressing the criteria and requirements specified in the German Site Selection Act. The results support BASE to review and define the surface-based exploration programs to be executed by the national implementer BGE (Bundesgesellschaft für Endlagerung mbH). To support BASE in reviewing the application of the exclusion criteria “active fault zones” according to the Site Selection Act, the project KaStör reviewed the current knowledge on active faults and fault zones in Germany and recommends methodological approaches to date and identify the activity of faulting. For the time being, the Site Selection Act defines 100 ∘C as a draft limit on the temperature at the outer surface of a repository container for all host rocks. The project Grenztemperatur studied the temperature dependency of the different thermal-hydraulic-mechanical-chemical/biological (THMC/B) processes according to available features-events-processes (FEP) catalogues for rock salt, clay stone, and crystalline rock and describes ways to defining host rock specific maximum temperatures based on specific disposal and safety concepts. Safety oriented weighting of different criteria and comparison of different potential regions and sites are key challenges during the siting process. The project MABeSt studied and reviewed methodological approaches to this weighting and comparison problem with special emphasis on multi criteria analysis (MCA) and multi criteria decision analysis (MCDA). A key requirement for safe geological disposal of nuclear waste is barrier integrity. The project PeTroS performed the first triaxial flow-through experiments on natural rock salt samples at disposal relevant p−T conditions and studied potential percolation mechanisms of fluids within rock salt. The data substantiate that the minimum stress criterion and/or the dilatancy criterion are the prime “percolation thresholds” in rock salt. The research results support BASE in fulfilling its tasks as national regulator according to state-of-the-art science and technology and are also relevant to other stakeholders of the siting process.

Li0.625Al0.125H0.25Cl0.75O0.25 Superionic Conductor with Disordered Rock-Salt Structure

2021 ◽  
Author(s):  
Qian Zhang ◽  
William Arnold ◽  
Zachary D. Hood ◽  
Yang Li ◽  
Rachel DeWees ◽  
...  
Keyword(s):  
Rock Salt ◽  
Superionic Conductor ◽  
Rock Salt Structure ◽  
Salt Structure

scholarly journals Experience of establishing and coordinating a nationwide network for bidirectional intussusception surveillance in India: lessons for multisite research studies

BMJ Open ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. e046827
Author(s):  
Manoja Kumar Das
Keyword(s):  
Quality Assurance ◽  
Site Selection ◽  
Information Seeking ◽  
Selection Process ◽  
Tertiary Care ◽  
Vaccine Safety ◽  
Secondary Outcome ◽  
Prospective Surveillance ◽  
Surveillance Network ◽  
Nationally Representative

ObjectivesTo document and share the process of establishing the nationally representative multisite surveillance network for intussusception in India, coordination, data management and lessons learnt from the implementation.DesignThis study combined both retrospective and prospective surveillance approaches.Setting19 tertiary care institutions were selected in India considering the geographic representation and public and private mixParticipantsAll children under-2 years of age with intussusceptionPrimary and secondary outcome measuresThe experience of site selection, regulatory approvals, data collection, quality assurance and network coordination were documented.ResultsThe site selection process involved systematic and objective four steps including shortlisting of potential institutions, information seeking and telephonic interaction, site visits and site selection using objective criteria. Out of over 400 hospitals screened across India, 40 potential institutions were shortlisted and information was sought by questionnaire and interaction with investigators. Out of these, 25 institutes were visited and 19 sites were finally selected to participate in the study. The multistep selection process allowed filtering and identification of sites with adequate capacity and motivated investigators. The retrospective surveillance documented 1588 cases (range: 14–652 cases/site) and prospective surveillance recruited 621 cases (range: 5–191 cases/site). The multilayer quality assurance measures monitored and ensured protocol adherence, complete record retrieval and data completeness. The key challenges experienced included time taken for obtaining regulatory and ethical approvals, which delayed completion of the study. Ten sites continued with another multisite vaccine safety surveillance study.ConclusionThe experience and results of this systematic and objective site selection method in India are promising. The systematic multistep site selection and data quality assurance methods presented here are feasible and practical. The lessons from the establishment and coordination of this surveillance network can be useful in planning, selecting the sites and conducting multisite and surveillance studies in India and developing countries.

Classification of Mason’s Skills by Analysis of Selected Churches of the Broumov Group

2021 ◽  
Vol 109 ◽  
pp. 15-20
Author(s):  
Pavel Kuklík ◽  
Martin Valek ◽  
Charalampos Paschopoulos
Keyword(s):  
Cultural Heritage ◽  
Bearing Capacity ◽  
Construction Industry ◽  
Economic Situation ◽  
Historical Events ◽  
Baroque Architecture ◽  
Current State ◽  
Geological Conditions ◽  
Local Construction

The churches of the Broumov region are renowned for their unique baroque architecture, their distinct shapes, and sizes. They are an integral part of the Czech cultural heritage. If you analyze the churches, it becomes evident that both the local geological conditions and the municipal economic situation have played an important role in their current condition. Moreover, the local construction industry has been significantly affected by historical events. In this article we would like to present the effects of those factors on the current state of selected churches, namely on the bearing capacity of their walls. Besides being very interesting, it also plays a key role in the maintenance and the potential reconstruction of the churches.

3D Web Visualization Tool to support HAYABUSA2-MASCOT Landing Site Selection Process

2018 ◽  
Author(s):  
Antoine F. Charpentier ◽  
Vivian Lafaille ◽  
Aurelie Moussi ◽  
Jean Christophe Malapert ◽  
Laurence Lorda ◽  
...  
Keyword(s):  
Site Selection ◽  
Selection Process ◽  
Landing Site ◽  
Visualization Tool ◽  
Web Visualization ◽  
3D Web ◽  
Landing Site Selection
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