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>

State of the scientific and technical knowledge about limiting temperatures in the Repository Site Selection process of Germany with simultaneous consideration to Europe and other European repository concepts

2020 ◽  
Author(s):  
Ute Maurer-Rurack ◽  
Axel Liebscher ◽  
Fabien Magri
Keyword(s):  
Outer Surface ◽  
Site Selection ◽  
Selection Process ◽  
Temperature Limit ◽  
Crystalline Rock ◽  
Technical Knowledge ◽  
Federal Republic Of Germany ◽  
Regulatory Frameworks ◽  
High Level ◽  
Limiting Temperatures

<p>The Federal Republic of Germany has decided to dispose its high-level radioactive waste in deep geological formations. Three types of host rock are considered: rock salt, clay rock and crystalline rock. The Site Selection Act (StandAG<sup>1</sup>), which came into effect on the 16<sup>th</sup> of May 2017, defines the successive steps of the repository siting process, which has to ensure the best possible safety conditions for a period of one million years. Based on precaution considerations, the StandAG (§27 (4) StandAG) sets a preliminary temperature limit of 100°C at the outer surface of a repository container for the preliminary safety assessment.</p><p>This contribution provides an overview about the state of the scientific and technical knowledge on the limiting temperatures in the repository site selection process of Germany. It also illustrates the different treatments of the definition of temperature limits within other European siting processes. The findings highlight that, in Europe, the proposed criteria which consider temperature at the outer surface of a repository container get more and more into focus of research and discussion especially for the three different types of host rocks.</p><p>After presenting the national regulatory frameworks, this contribution summarizes how the European countries address the different temperature related issues for their site selection, their repository concepts and how in turn these all can influence the German safety case strategy for the German site selection. Not at least, links to site selection criteria in other countries (e.g. USA, Japan, Russia) are provided.</p><p><strong>Reference</strong></p><p><sup>1</sup>  StandAG: Standortauswahlgesetz vom 5. Mai 2017 (BGBl. I S. 1074), das zuletzt durch Artikel 2 Absatz 16 des Gesetzes vom 20. Juli 2017 (BGBl. I S. 2808) geändert worden ist.</p>

scholarly journals On the temperature in a final disposal site for high-level radioactive waste

2021 ◽  
Vol 1 ◽  
pp. 99-100
Author(s):  
Ute Maurer-Rurack ◽  
Guido Bracke ◽  
Eva Hartwig-Thurat ◽  
Artur Meleshyn ◽  
Torben Weyand
Keyword(s):  
Radioactive Waste ◽  
Outer Surface ◽  
Site Selection ◽  
Temperature Limit ◽  
Disposal Site ◽  
Final Disposal ◽  
High Level Radioactive Waste ◽  
High Level ◽  
Host Rocks ◽  
Respective Host

Abstract. The Site Selection Act stipulates a precautionary temperature limit of 100 ∘C on the outer surface of the containers with high-level radioactive waste (HLRW) in the final disposal site. This precautionary temperature limit should 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. Increasing temperatures in the deep geological underground, caused by the heat generation of the HLRW, can trigger thermal, hydraulic, mechanical, chemical and biological processes (THMCB) in the respective host rocks of a final disposal site and thus endanger safety. Furthermore, high temperatures may hamper the feasibility to retrieve and recover HLRW from a final disposal site. Such processes are described in detail in databases for features, events and processes (FEP) databases. Single components or barriers of a final disposal facility may require specific design temperatures for the preservation of their features once a concept for long-term safety of a final disposal site is established; however, the interactions of all relevant processes of a concept for a final disposal site must be considered when a specific temperature limit for the outer surface of the containers is derived. This temperature limit may vary for particular safety and final disposal concepts in the host rock: salt, clay and crystalline rock. The conclusion is that temperature limits regarding the outer surface of the containers should be derived specifically for each safety and disposal concept and should be supported by a solid safety analysis. Temperature limits without reference to specific safety concepts or the particular design of the final disposal site likely narrow down the possibilities for optimisation and could adversely affect the site selection process in finding the best suitable site.

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.

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 Measurement Methods for Above-ground Site Investigation Programmes according to StandAG (Project “MessEr”) – an Overview

2021 ◽  
Vol 1 ◽  
pp. 59-60
Author(s):  
Ingo Kock ◽  
Michael Jendras ◽  
Thorsten Faß ◽  
Gerd Frieling ◽  
Wolfram Wartenberg ◽  
...  
Keyword(s):  
Site Selection ◽  
Selection Process ◽  
Site Investigation ◽  
Crystalline Rock ◽  
Measurement Methods ◽  
Main Task ◽  
Federal Law ◽  
Federal Authority ◽  
Investigation Methods ◽  
High Level

Abstract. In Germany, the site selection process for a repository for high-level radioactive waste is stipulated by the Site Selection Act (Standortauswahlgesetz – StandAG). During the site selection process, the implementer has to identify and propose siting regions. The Federal Office for the Safety of Nuclear Waste Management (Bundesamt für die Sicherheit der nuklearen Entsorgung – BASE) as the responsible federal authority has to review the implementer's proposal and finally the siting regions remaining in the site selection process will be laid down by federal law. The corresponding above-ground site investigation programmes submitted by the implementer will also be reviewed and then determined by BASE. These programmes and subsequent revisions have to be published by BASE in the Federal Gazette (§ 15 StandAG). When reviewing as well as determining above-ground site investigation programmes, state-of-the-art science and technology have to be considered – especially in the field of applied measurement methods. For this reason, it is convenient to have a catalogue of relevant and available measurement methods. This overview shows the findings and results from the project “MessEr”, which was carried out by GRS gGmbH and initiated and funded by BASE (funding code/FKZ 4717F01202). To derive such a catalogue for the above-ground site investigation within the site selection process the project “MessEr” (Messmethoden für übertägige Erkundungsprogramme gemäß StandAG – Measurement methods for surface-based exploration programmes in accordance with the StandAG) was initiated by BASE. This catalogue should combine two key features: (i) it should be understandable not only for experts but also for interested members of the general public and (ii) it also should provide a basis to evaluate proposed site investigation programmes. Accordingly, the main task within the project was to compile above-ground measurement methods considering the three host rocks according to the StandAG – rock salt, clay rock and crystalline rock – and to classify them with regard to the kind of investigation, measuring principles and achievable knowledge. In a second step, every single measurement method had to be characterised and described in detail: advantages, disadvantages and efforts, as well as limitations and uncertainties. Furthermore, aspects such as applicability (with regard to the host rock), the combination of different methods and any possible needs of research and development were discussed. For further information, references such as standard textbooks, weblinks, journals or reports from other international repository projects were compiled for each method. The final step of “MessEr” was to evaluate Appendices 1 to 12 to § 24 StandAG (“geoscientific consideration criteria”) with respect to their significance and requirements for above-ground site investigation methods. This resulted in three matrices showing the correlations of required parameters and necessary knowledge according to the StandAG with the compiled measurement methods.

Stepwise Site Selection in Switzerland: Sectoral Plan Status and Outlook

2010 ◽  
Author(s):  
Thomas Ernst ◽  
Markus Fritschi ◽  
Stratis Vomvoris
Keyword(s):  
Site Selection ◽  
Selection Process ◽  
Local Level ◽  
Nuclear Safety ◽  
Public Consultation ◽  
High Level Waste ◽  
Waste Site ◽  
High Level ◽  
A Site ◽  
Stage 1

The stepwise site selection process in Switzerland is governed by the Sectoral Plan. It is divided in three stages, narrowing down the number of potential siting regions (Stage 1) to at least two sites for each of the two geological repositories, the low and intermediate-level waste site (LLW) and the high-level waste site (HLW), in Stage 2, leading to the final selection of a site for each repository (Stage 3) for the application of a general license. In October 2008, Nagra proposed a total of 6 siting regions for the LLW repository and three for the HLW repository; the latter would also be suitable for shared use with the surface facilities and part of the access tunnels for the two types of repositories. The review of Nagra’s proposals by the safety authority (ENSI — the Swiss Federal Nuclear Safety Inspectorate) and its supporting commission was completed in February 2010. ENSI found Nagra’s analysis justified comprehensive and transparent and approved the six proposed regions. A similar overall conclusion was reached by KNS, the Swiss Commission for Nuclear Safety. The decision-making process continues in 2010 with an evaluation of the review and recommendations of ENSI by the various agencies at the governmental, cantonal and local level, an open public consultation and finally, a resolution of the comments received by the Swiss Federal Office of Energy (SFOE). Stage 1 will be concluded in 2011 with the decision by the Swiss Federal Government. Stage 2 foresees a provisional safety analysis for each potential site as an additional criterion to be used in the narrowing down to two sites for each type of waste repository. The guidelines for this have been recently published by ENSI. The main findings of the review by the authorities, the next steps and preparatory activities for the initiation of Stage 2, as well as how the criteria and guidelines specified by ENSI will be applied by Nagra in order to meet the requirements for a successful completion of Stage 2 are described below.

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>

Centralization of Canada’s Spent Nuclear Fuel

2013 ◽  
Author(s):  
Krista Nicholson ◽  
John McDonald ◽  
Shona Draper ◽  
Brian M. Ikeda ◽  
Igor Pioro
Keyword(s):  
Nuclear Fuel ◽  
Site Selection ◽  
Nuclear Power ◽  
Power Plants ◽  
Spent Nuclear Fuel ◽  
Selection Process ◽  
Spent Fuel ◽  
Geologic Repository ◽  
Candu Reactors ◽  
High Level

Currently in Canada, spent fuel produced from Nuclear Power Plants (NPPs) is in the interim storage all across the country. It is Canada’s long-term strategy to have a national geologic repository for the disposal of spent nuclear fuel for CANada Deuterium Uranium (CANDU) reactors. The initial problem is to identify a means to centralize Canada’s spent nuclear fuel. The objective of this paper is to present a solution for the transportation issues that surround centralizing the waste. This paper reviews three major components of managing and the transporting of high-level nuclear waste: 1) site selection, 2) containment and 3) the proposed transportation method. The site has been selected based upon several factors including proximity to railways and highways. These factors play an important role in the site-selection process since the location must be accessible and ideally to be far from communities. For the containment of the spent fuel during transportation, a copper-shell container with a steel structural infrastructure was selected based on good thermal, structural, and corrosion resistance properties has been designed. Rail has been selected as the method of transporting the container due to both the potential to accommodate several containers at once and the extensive railway system in Canada.

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.

scholarly journals Geochemical benchmark tests to validate the conversion of thermodynamic data for TOUGHREACT

2021 ◽  
Vol 1 ◽  
pp. 161-162
Author(s):  
Torben Weyand ◽  
Holger Seher ◽  
Guido Bracke
Keyword(s):  
Nuclear Waste ◽  
Waste Disposal ◽  
Thermodynamic Data ◽  
Selection Process ◽  
Nuclear Waste Disposal ◽  
Crystalline Rock ◽  
Benchmark Tests ◽  
High Level ◽  
Saline Solutions

Abstract. According to the ongoing site selection process for a repository for high-level radioactive waste in Germany, rock salt, clay and crystalline rock are possible host rocks. The pore water of these rocks contains saline solutions with high ionic strengths. To model the speciation and/or migration of radionuclides in long-term safety analyses for nuclear waste disposal, a geochemical code that includes thermodynamic data suitable for saline solutions is needed. Thermodynamic equilibrium in saline solutions with high ionic strengths is usually modelled using the Pitzer approach (Pitzer, 1991). Within the context of nuclear waste disposal, the THEREDA project (Moog et al., 2015) provides thermodynamic data for some widely used geochemical codes (PHREEQC, Geochemist's Workbench, ChemApp, and EQ 3/6) using the Pitzer approach; however, for modelling in long-term safety analyses for nuclear waste disposal, another geochemical code, TOUGHREACT, is used. Therefore, scripts were developed to convert thermodynamic data of the THEREDA project to be applicable in TOUGHREACT. The scripts were validated by benchmark tests and by comparing calculations using PHREEQC and TOUGHREACT (Weyand et al., 2021). In total, 50 different benchmark tests were performed considering 3 specific geochemical systems, which are relevant to long-term safety analyses: (1) oceanic salt system, polythermal: K, Mg, Ca, Cl, SO4, H2O(l), (2) actinide system, isothermal: Am(III), Cm(III), Nd(III), Na, Mg, Ca, Cl, OH, H2O(l) and (3) carbonate system, isothermal: Na, K, Mg, Ca, Cl, SO4, HCO3/CO2(g), H2O(l). Each benchmark test considered specific ion concentrations in solution and in gaseous phases in the presence of specific minerals. The benchmark tests derived the geochemical equilibria and the results of both codes were compared to each other and to experimental data. The results of the calculations using both codes showed a good correlation. Remaining deviations can be explained by technical differences of the codes.

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