scholarly journals Suitability of flat bedded salt formations in Germany as the site for a repository for heat-producing radioactive waste

2021 ◽  
Vol 1 ◽  
pp. 43-44
Author(s):  
Till Popp ◽  
Ralf-Michael Günther ◽  
Dirk Naumann
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Selection Procedure ◽  
Crystalline Rock ◽  
Toxic Waste ◽  
Northwest Germany ◽  
Geological Barrier ◽  
Bedded Salt Formations ◽  
A Site

Abstract. The search for a site of a final repository for highly radioactive waste in Germany was renewed when the Site Selection Act (StandAG) came into force in 2013. In Germany the development of concepts for a final repository and safety analyses for a repository in a salt dome was prioritized for many decades, whereas repository concepts in clay and crystalline rock were first considered only two decades ago. The aim of a comparative site selection procedure is to find a site before 2031, which provides the best possible safety for the enclosure of highly radioactive waste over a time period of 1 million years. The fundamental safety-related consideration is the enclosure of toxic waste in a so-called containment effective geological area (ewG). The main aspect of a long-term proof of safety is logically the systematic proof of safe long-term enclosure of the deposited waste. The approach developed within the framework of appropriate research projects (e.g. Eickemeier et al., 2013) is essentially based on the proof of geotechnical integrity of the ewG as the fundamental geological barrier as well as the geotechnical barriers. Due to their unique characteristics, including imperviousness and plastic deformability, salt rocks have been used for decades in Germany and worldwide in mining and especially for energy storage. Whereas halite in salt domes (type steep​​​​​​​ inclined salt) is distributed particularly in northwest Germany, flatly deposited salt rock (type flat bedded salt​​​​​​​) dominates in middle Germany and salt pillows (type salt pillows) in parts of northeast Germany. Both types of “bedded salt”​​​​​​​ widely reflect in their lateral extension sedimentation-related deposition conditions, apart from diagenetically related alterations. Beginning with the presentation of the host rock-specific boundary conditions of the various rock salts, this article focuses on the appropriate procedures for the proof of integrity of the geological barrier rock salt, based on the available experiences, corresponding reference studies and analogous examples. In the results it is shown that repository concepts in bedded salt formations and especially in the constellation of salt pillows provide substantial safety-related advantages due to a site-specific multibarrier system with alternate deposition of salt and saliferous clay as well as an intact overlying rock covering.

scholarly journals Preliminary safety analyses in the high-level radioactive waste site selection procedure in Germany

2021 ◽  
Vol 56 ◽  
pp. 67-75
Author(s):  
Eva-Maria Hoyer ◽  
Elco Luijendijk ◽  
Paulina Müller ◽  
Phillip Kreye ◽  
Florian Panitz ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Selection Procedure ◽  
Crystalline Rock ◽  
Radioactive Waste Disposal ◽  
High Level Radioactive Waste ◽  
Long Term Storage ◽  
Geological Conditions ◽  
High Level ◽  
A Site

Abstract. The Federal Company for Radioactive Waste Disposal (BGE) is responsible for the search for a site with the best possible safety for the disposal of high-level radioactive waste in Germany. The site selection procedure is regulated in a law that was adopted by the German Federal Parliament (Repository Site Selection Act – StandAG, 2017, last updated 2020) and aims to be a participatory, transparent, learning, and self-questioning process based on scientific expertise. The first step of the first phase of the site selection procedure was completed in September 2020 and resulted in the identification of sub-areas that give reason to expect favorable geological conditions for the long-term storage of nuclear waste in the subsurface. These sub-areas cover approximately 54 % of Germany and are located in three different host rocks: rock salt – halite, claystone, and crystalline rock. The challenge for the next step is to find suitable siting regions within the previously determined sub-areas that are then considered further in the next phase of the site selection procedure. In the following, the methodology of the so-called representative preliminary safety analyses is described, which constitute one of the tools to identify siting regions, and some first insight on how they are planned to be implemented in practice is given.

scholarly journals Development of a database for the analysis of the disposal system in the representative preliminary safety analysis

2021 ◽  
Vol 1 ◽  
pp. 39-40
Author(s):  
Eva-Maria Hoyer ◽  
Paulina Müller ◽  
Phillip Kreye ◽  
Christoph Behrens ◽  
Marc Wengler ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Selection Procedure ◽  
Crystalline Rock ◽  
Radioactive Waste Disposal ◽  
Future Evolution ◽  
Technical Parameters ◽  
Geological Setting ◽  
Geological Conditions ◽  
High Level

Abstract. The Federal Company for Radioactive Waste Disposal (BGE) is the German waste management organisation responsible for implementing the search for a site with the best possible safety for the disposal of high-level radioactive waste for at least 1 million years, following the amendments of the Repository Site Selection Act in 2017. The selection procedure is meant to be a participatory, transparent, learning and self-questioning process based on scientific expertise. It consists of three phases with an increasing level of detail. The first step of the first phase of the site selection procedure was completed in September 2020 and resulted in the identification of 90 subareas that give reason to expect favourable geological conditions for the safe disposal. The potentially suitable subareas cover approximately 54 % of Germany and are located in three different host rocks: rock salt (halite), claystone and crystalline rock. The second step of phase one is currently in progress and includes the so-called representative preliminary safety analyses that aim to assess the extent to which the safe containment of the radioactive waste can be expected. Representative preliminary safety analyses are one of the foundations for deciding whether an area will be considered for surface-based exploration in the next phase of the site selection procedure. Within the preliminary safety analyses, the behaviour of the disposal system is analysed in its entirety, across all operational phases of the repository and under consideration of possible future evolution of the disposal system with respect to the safe containment of the radioactive waste. The development of a database is described, which aims to systematically document and provide the framework needed for the analyses of the disposal systems in the subareas regarding the safe containment of the radionuclides over the assessment period of 1 million years. This database includes the vast amount of information about the different components of the disposal system. This includes also the geological setting, the technical conception of the repository and compilations of values for the physical, geoscientific, and technical parameters characterising the various barriers of the disposal system. Furthermore, a self-contained derivation of expected and deviating future evolution of the disposal system and its geological setting is included; following the so-called features, events and processes (FEP) strategy.

Preliminary safety assessments in the high-level radioactive waste site selection procedure in Germany

2021 ◽  
Author(s):  
Eva-Maria Hoyer ◽  
Christoph Behrens ◽  
Merle Bjorge ◽  
Julia Dannemann ◽  
Dennis Gawletta ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Selection Procedure ◽  
Crystalline Rock ◽  
Radioactive Waste Disposal ◽  
Seismic Exploration ◽  
High Level Radioactive Waste ◽  
Geological Conditions ◽  
Safety Assessments ◽  
High Level

<p>The Federal Company for Radioactive Waste Disposal mbH (BGE mbH) is as Germans waste management organization responsible to implement the search for a site with the best possible safety for the disposal of high-level radioactive waste for at least one million years, following the amendments of the Repository Site Selection Act in 2017. The selection procedure is meant to be a participatory, transparent, learning and self-questioning process based on scientific expertise.</p><p>This contribution will provide an overview of the methodology of the forthcoming preliminary safety assessments as a major part of the next steps in the site selection procedure. This procedure overall consists of three phases with increasing level of detail for identification of the best site. The first phase consists of two steps. The objective of the first step was to determine sub-areas in the three considered host rocks, salt (halite), clay and crystalline rock, by applying legally defined exclusion criteria, minimum requirements and geoscientific weighing criteria. 90 sub-areas that cover approximately 54 % of the area of Germany were identified due to their general suitable geological conditions. The result was published in September 2020.</p><p>The second step of phase one is currently in progress and consists of representative preliminary safety assessments that aim to assess the safety of the repository system as well as its robustness. The requirements for the preliminary safety assessments in the site selection procedure are defined by a governmental directive released in October 2020. Representative preliminary safety assessments have to be performed for each sub-area and consist of the compilation of all geoscientific information relevant to the safety of a repository, the development of preliminary safety and repository concepts and the analysis of the repository system. In addition, a systematically identification and characterization of uncertainties has to be undertaken and the need for exploration, research and development must be determined. The application of the representative preliminary safety assessments as well as the following renewed application of geoscientific weighing criteria will lead to the identification of siting regions within the larger sub-areas of step one. These regions will be considered, first for surface-based geoscientific and geophysical exploration, including i.e. seismic exploration and drilling of boreholes. Subsequently the last phase of the site selection will proceed with subsurface exploration. Finally, all suitable sites will be proposed and the German government will decide the actual site. This process is expected to be finalized in 2031.</p>

Significance of long-term climate evolution and associated impacts on the long-term safety of a high-level radioactive waste repository within the German siting process

2021 ◽  
Author(s):  
Marc Wengler ◽  
Astrid Göbel ◽  
Eva-Maria Hoyer ◽  
Axel Liebscher ◽  
Sönke Reiche ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Phase 1 ◽  
High Level Radioactive Waste ◽  
Safety Requirements ◽  
Climate Evolution ◽  
Safety Assessments ◽  
High Level ◽  
Host Rocks

<p>According to the 'Act on the Organizational Restructuring in the Field of Radioactive Waste Disposal' the BGE was established in 2016. The amended 'Repository Site Selection Act' (StandAG) came into force in July 2017 and forms the base for the site selection by clearly defining the procedure. According to the StandAG the BGE implements the participative, science-based, transparent, self-questioning and learning procedure with the overarching aim to identify the site for a high-level radioactive waste (HLW) repository in a deep geological formation with best possible safety conditions for a period of one million years.</p><p>The German site selection procedure consists of three phases, of which Phase 1 is divided into two steps. Starting with a blanc map of Germany, the BGE completed Step 1 in September 2020 and identified 90 individual sub-areas that provide favorable geological conditions for the safe disposal of HLW in the legally considered host rocks; rock salt, clay and crystalline rock. Based on the results of Step 1, the on-going Step 2 will narrow down these sub-areas to siting regions for surface exploration within Phase 2 (§ 14 StandAG). Central to the siting process are representative (Phase 1), evolved (Phase 2) and comprehensive (Phase 3) preliminary safety assessments according to § 27 StandAG.</p><p>The ordinances on 'Safety Requirements' and 'Preliminary Safety Assessments' for the disposal of high-level radioactive waste from October 2020 regulate the implementation of the preliminary safety assessments within the different phases of the siting process. Section 2 of the 'Safety Requirements' ordinance provides requirements to evaluate the long-term safety of the repository system; amongst others, it states that all potential effects that may affect the long-term safety of the repository system need to be systematically identified, described and evaluated as “expected” or “divergent” evolutions. Additionally, the ordinance on 'Preliminary Safety Assessments' states in § 7, amongst others, that the geoscientific long-term prediction is a tool to identify and to evaluate geogenic processes and to infer “expected” and “divergent” evolutions from those. Hence, considering the time period of one million years for the safe disposal of the HLW and the legal requirements, it is essential to include long-term climate evolution in the German site selection process to evaluate the impact of various climate-related scenarios on the safety of the whole repository system.</p><p>To better understand and evaluate the influence of climate-related processes on the long-term safety of a HLW repository, climate-related research will be a part of the BGE research agenda. Potential research needs may address i) processes occurring on glacial – interglacial timescales (e.g. the inception of the next glaciation, formation and depth of permafrost, glacial troughs, sub-glacial channels, sea-level rise, orbital forcing) and their future evolutions, ii) effects on the host rocks and the barrier system(s) as well as iii) the uncertainties related to these effects but also to general climate models and predictions.</p>

Methodology of preliminary safety assessments in the site selection procedure in Germany

2020 ◽  
Author(s):  
Wolfram Rühaak ◽  
Phillip Kreye ◽  
Eva-Maria Hoyer ◽  
Johanna Wolf ◽  
Florian Panitz ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Reactive Transport ◽  
Selection Procedure ◽  
Transport Modelling ◽  
Safety Requirements ◽  
Safety Assessments ◽  
High Level ◽  
Geological Formations

<p><span>In Germany, the site selection for a repository for radioactive waste in deep geological formations was (re-) started in 2017 with the Repository Site Selection Act coming into force. The Site Selection Act envisages preliminary safety assessments as a measure to ensure the safety of a considered site.</span></p><p><span>The focus of the presentation will be the methodology of the preliminary safety assessments as it is derived from the legal requirements. In this context, the Federal Ministry for Environment, Nature Conservation and Nuclear Safety published the draft of the regulation on the safety requirements for the disposal of high-level radioactive waste in summer 2019. Article 2 of this regulation contains the requirements for the implementation of preliminary safety assessments in the site selection procedure. One essential aspect is the systematical identification and characterization of uncertainties. We will discuss the key features of the handling of uncertainties in the site selection procedure, especially with regard to numerical reactive transport modelling. The German Site Selection Act is divided into several steps with increasing level of detail. The identification and quantification of uncertainties plays a major role to improve quality and plausibility in each step. Well-prepared explorations for instance, need to be addressed in a way to minimise data uncertainties. In addition, the handling of uncertainties in safety assessments on an international level is evaluated. </span></p>

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 Section 14 StandAG – Identification of siting regions and associated challenges

2021 ◽  
Vol 1 ◽  
pp. 49-50
Author(s):  
Lisa Seidel ◽  
Marc Wengler
Keyword(s):  
Radioactive Waste ◽  
Phase I ◽  
Site Selection ◽  
Selection Procedure ◽  
Radioactive Waste Disposal ◽  
Second Step ◽  
High Level Radioactive Waste ◽  
Surface Exploration ◽  
Safety Assessments ◽  
High Level

Abstract. With the publication of the subarea interim report on sub-regions on 28 September 2020, the Federal Company for Radioactive Waste Disposal (BGE), as the implementer of the German site selection procedure, has completed the first step of phase I in due time. The second step of phase I is the identification of siting regions for surface exploration. In the following step 2 of phase I, the determination of siting regions for surface exploration will be carried out based on the interim results of the first step of phase I in accordance with section 14 of the regulating law (StandAG). A central component of this second step of phase I is the representative preliminary safety assessments pursuant to section 27 StandAG, the ordinances on “Safety Requirements” (EndlSiAnfV) and “Preliminary Safety Assessments” (EndlSiUntV), which are carried out for each of the sub-regions. Based on the results of the preliminary safety assessments and the renewed application of the geoscientific weighting criteria (section 24 StandAG), siting regions will be identified that have the potential to become the site with the best possible safety for a repository for high-level radioactive waste. During the second step of phase I, the planning scientific consideration criteria (section 25 StandAG) can be applied for the first time. The path to the siting regions for surface exploration can be accompanied by various challenges related to geoscientific, methodological and also societal questions. For example, the application of the representative preliminary safety assessments may be more challenging in larger subareas compared to smaller ones as subsurface properties are likely to be more variable. In this context, areas with little data coverage for example, and the treatment of these areas in the procedure may pose another challenge. Therefore, sound methodological concepts must be developed for performing the representative preliminary safety assessments as well as for applying the geoscientific weighting criteria. Furthermore, the German site selection procedure defines special requirements (section 1 StandAG): the implementation of the participatory, science-based, transparent, self-questioning and learning procedure poses challenges to all stakeholders of the procedure on the way to the best possible disposal of high-level radioactive waste.

scholarly journals Identification and evaluation of processes for joint disposal of high level radioactive waste and low to intermediate level radioactive waste

2021 ◽  
Vol 1 ◽  
pp. 183-184
Author(s):  
Andreas Poller ◽  
Susie M. L. Hardie ◽  
Gerhard Mayer ◽  
Marie Pijorr ◽  
Joachim Poppei ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Selection Procedure ◽  
Crystalline Rock ◽  
Intermediate Level ◽  
Clay Rock ◽  
High Level Radioactive Waste ◽  
Quantitative Analyses ◽  
Intermediate Level Radioactive Waste ◽  
High Level ◽  
Qualitative Analyses

Abstract. The on-going research project „Identification and evaluation of processes that can arise by disposing of both high level radioactive waste (HAW) and low to intermediate level radioactive waste (LAW/MAW) at the same site“ (GemEnd, FKZ 4719F10401), commissioned by the Federal Office for the Safety of Nuclear Waste Management (BASE), is concerned with the question which thermal, hydraulic, mechanical, chemical and biological (THMCB) processes could be of importance for the long-term safety of the geological repository for high level radioactive waste. The focus of the project is on mutual influences between the HAW and LAW/MAW repositories, which should be constructed separately according to the Safety Regulations (Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, BMU, 2020). A second point of emphasis is on processes that could result from the disposal of small amounts of LAW/MAW within the HAW repository. The analyses carried out for each of the potential host rocks clay rock, rock salt and crystalline rock as well as for a combination of clay rock above crystalline rock at a generic site are divided into a qualitative and a quantitative part. As for the qualitative analyses, all potentially relevant processes are identified and evaluated as to whether they are negligible or principally relevant for the exemplary repository configurations considered and according to the current state of knowledge. With regard to the quantitative analyses, the possible extent of potentially safety-relevant processes is illustrated by means of coupled numerical simulations. Of special interest are the effects of particularly sensitive model approaches and/or parameters and notably of the distances between the HAW and LAW/MAW repositories in the different exemplary repository configurations considered. From the results of the quantitative and qualitative analyses, knowledge gaps will be identified and the possibility of their reduction by research and development activities will be discussed. Furthermore, aspects of the transferability of the results to the German site selection procedure will be illuminated. At the interdisciplinary research symposium safeND selected preliminary results of both the qualitative and quantitative analyses will be presented.

scholarly journals From process to system understanding with multi-disciplinary investigation methods: set-up and first results of the CD-A experiment (Mont Terri rock laboratory)

2021 ◽  
Vol 1 ◽  
pp. 79-81
Author(s):  
Gesa Ziefle ◽  
Tuanny Cajuhi ◽  
Sebastian Condamin ◽  
Stephan Costabel ◽  
Oliver Czaikowski ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Fault Zones ◽  
Rock Laboratory ◽  
Investigation Methods ◽  
Physical Effects ◽  
Mont Terri ◽  
Mont Terri Rock Laboratory ◽  
The Impact

Abstract. A potential repository site for high-level radioactive waste should ensure the highest possible safety level over a period of one million years. In addition to design issues, demonstrating the integrity of the barrier is essential as it ensures the long-term containment of radioactive waste. Therefore, a multi-disciplinary approach is necessary for the characterization of the surrounding rock and for the understanding of the occurring physical processes. For site selection, however, the understanding of the respective system is essential as well: Do fault zones exist in the relevant area? Are these active and relevant for interpreting system behavior? What is the role of the existing heterogeneities of the claystone and how do these site-dependent conditions influence the physical effects? To answer these questions, the site-selection procedure requires underground exploration, which includes geophysical and geological investigations on milli- to decameter scales. Their results serve as the basis for numerical modelling. This combined, multi-disciplinary interpretation requires extensive knowledge of the various methods, their capabilities, limitations, and areas of application. In the cyclic deformation (CD-A) experiment in the Mont Terri rock laboratory, the hydraulic–mechanical effects due to excavation and the climatic conditions within the rock laboratory are investigated in two niches in the Opalinus Clay. The twin niches differ mainly with regard to the relative humidity inside them, but are also characterized by different boundary conditions such as existing fault zones, the technical construction of the neighboring gallery, etc. In order to gain insights into the relevance of the individual influences, comparative studies are being carried out on both niches. The presented results provide a first insight into the initial experimental years of the CD-A long-term experiment and illustrate the benefits of multi-disciplinary investigations in terms of system understanding and the scale dependency of physical effects. Amongst other effects, the assessment of the impact of heterogeneities on the deformation behavior and the evolution of pore water pressure is very complex and benefits from geological interpretation and measurements of for example deformation, water content, and pore pressure. The numerical modeling allows statements about the interaction of different processes and thus enables an interpretation of the overall system, taking into account the knowledge gained by the multi-disciplinary investigation.

scholarly journals Status of Deep Borehole Disposal of High-Level Radioactive Waste in Germany

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2580 ◽  
Author(s):  
Guido Bracke ◽  
Wolfram Kudla ◽  
Tino Rosenzweig
Keyword(s):  
Radioactive Waste ◽  
Site Selection ◽  
Real Option ◽  
Selection Process ◽  
Technical Equipment ◽  
Deep Borehole ◽  
Final Disposal ◽  
High Level Radioactive Waste ◽  
High Level ◽  
A Site

The phase-out of nuclear energy in Germany will take place in 2022. A site for final disposal of high-level radioactive waste (HLRW) has not yet been chosen, but a site selection process was restarted by the Site Selection Act in 2017. This Act was based on a recommendation by a commission which also advised to follow up the development of deep borehole disposal (DBD) as a possible option for final disposal of HLRW. This paper describes briefly the status of DBD in Germany and if this option is to be pursued in Germany. Although DBD has some merits, it can only be a real option if supported by research and development. The technical equipment for larger boreholes of the required size will only be developed if there is funding and a feasibility test. Furthermore, any DBD concept must be detailed further, and some requirements of the Act must be reconsidered. Therefore, the support of DBD will likely remain at a low level if there are no political changes.

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