Simulations of long-term anaerobic corrosion of carbon steel containers in Canadian deep geological repository

2014 ◽  
Vol 49 (6) ◽  
pp. 455-459 ◽  
Author(s):  
F. King ◽  
M. Kolář ◽  
P. G. Keech
Keyword(s):  
Carbon Steel ◽  
Deep Geological Repository ◽  
Geological Repository ◽  
Anaerobic Corrosion

scholarly journals Assessment of the climate changes evolution for the long-term safety of the radioactive waste repository in the Czech Republic

2019 ◽  
Vol 133 ◽  
pp. 02005
Author(s):  
Markéta Camfrlová
Keyword(s):  
Czech Republic ◽  
Radioactive Waste ◽  
Spent Nuclear Fuel ◽  
Global Climate ◽  
Deep Geological Repository ◽  
Climatic Effects ◽  
The Czech Republic ◽  
Area Of Interest ◽  
Geological Repository

Nuclear energy accounts for a significant part of the total energy production in the Czech Republic, which is currently facing a problem dealing with the high-level radioactive waste (HLW) and the spent nuclear fuel (SNF). Deep repository is the safest option for storage of HLW. Rock environment of the area must guarantee the stability of the deep geological repository for at least 100,000 years. The aim of the research is a long-term evaluation of the climatic changes of the hypothetical area of interest, which corresponds to the candidate sites for deep geological repository in the Czech Republic. The occurrences of endogenous and exogenous phenomena, which could affect site stability, were evaluated. Concerning exogenous processes, research focuses mainly on the assessment of climatic effects. The climate scenarios for the Central Europe were examined – global climate change, glaciation, and the depth of permafrost as well as CO2 increase.

scholarly journals Assessment of the impact of selected changes in the deep geological repository model on its long-term safety

2020 ◽  
Vol 225 ◽  
pp. 06012
Author(s):  
Dorota Flamíková ◽  
Vladimír Nečas
Keyword(s):  
Effective Dose ◽  
Annual Effective Dose ◽  
Monitoring Program ◽  
Distribution Coefficients ◽  
Exposure Group ◽  
Deep Geological Repository ◽  
Adult Individual ◽  
Geological Repository ◽  
The Impact

The deep geological repository system provides long-term protection against the undesirable effects of ionizing radiation on the population and the environment. An important part of the long-term safety strategy is development of a monitoring program that collects information about the behaviour of the deep geological repository throughout its whole lifetime. A simplified model of the disposal system, geosphere, and biosphere was developed using the GoldSim simulation tool to demonstrate the behaviour of the hypothetical deep geological repository located in crystalline rocks. Also an initial model of the reference biosphere was created based on the scenario of an agricultural habitation (normal evolution scenario) and it was developed based on the recommendations provided in the BIOMASS methodology. After a significant period of time, disposal containers will be degraded and evolution changes in the repository system will occur. Several important parameters appear in the annual effective dose calculation for an individual from critical exposure group within the reference biosphere model. One of them are, for example, distribution coefficients and so-called translocation factors that define the transported rate of released radionuclides into the environment. This paper provides a view into the selected part of the deep geological repository through the data obtained by monitoring during the selected period of time. Simulations describing changes in the repository system. The aim of this contribution is to evaluate the impact of selected changes on the annual effective dose for an adult individual from a critical exposure group while it is assumed, that the respondent consumes contaminated crops and animal products. This model includes various biosphere components and multiple exposure pathways such as inhalation, ingestion and external exposure.

Retrievability: A False Positive?!?

2001 ◽  
Author(s):  
Leif G. Eriksson
Keyword(s):  
False Positive ◽  
Future Generations ◽  
Public Acceptance ◽  
Public Confidence ◽  
Deep Geological Repository ◽  
Preliminary Conclusion ◽  
The Public ◽  
Geological Repository ◽  
Deep Geological Repositories

Abstract Retrieval (and various permutations of this term) of long-lived radioactive wastes/materials (LLRMs) from deep geological repositories is a “concept” currently believed to increase public confidence in, and acceptance of, national LLRM-repository programs. If the “retrievability concept” provides the missing link to increased public acceptance, which is imperative in a democratic society for the siting and development of a deep LLRM repository, then the understanding and expectations of the terms used must be clearly defined, and the associated benefits and shortcomings clearly explained, to the public. To quote the Danish mathematician and philosopher Piet Hein: Knowing what you knowest not is in a sense omniscience. Based on more than 20 years of involvement in the development of deep geological repositories for LLRMs in the United Sates of America and abroad, it is the preliminary conclusion of this author that retrievability conveys a false positive because it: 1. Does not add any appreciable post-closure physical safety to current and future generations and environments. 2. Could compromise (but does not necessarily have to) the long-term integrity of the disposal system. 3. Conveys the erroneous message that this generation does not have confidence in its ability to design, construct, decommission, and close a deep geological repository for LLRMs, in a manner that provides long-term containment and isolation of the emplaced LLRMs.

scholarly journals Transdisciplinary research on the topic of long-term near-field monitoring of a geological repository with a view to building trust

2021 ◽  
Vol 1 ◽  
pp. 271-273
Author(s):  
Johann Arne Othmer ◽  
Karl-Heinz Lux ◽  
Ralf Wolters ◽  
Jörg Feierabend
Keyword(s):  
Civil Society ◽  
Radioactive Waste ◽  
Near Field ◽  
Field Monitoring ◽  
Deep Geological Repository ◽  
Geological Repository ◽  
Deep Geological Disposal ◽  
Long Term Monitoring ◽  
Term Monitoring

Abstract. Within the framework of disposal of radioactive waste in Germany, the question arises how trust in the safety of a future deep geological repository and therefore the acceptability can be increased. One aspect that could contribute to this is the option of long-term monitoring of a deep geological repository by participation of the civil society. Whether and exactly how long-term monitoring of a deep geological repository leads to more trust, is being researched in the transdisciplinary work package TRUST within the research project TRANSENS in cooperation with members of the civil society. For the transdisciplinary processing of specific repository topics, a group of 16 persons from the civil society were recruited, none of which were stakeholders with respect to the topic of repositories. This group is designated as the Working Group Civil Society (AGBe). With the help of 12 members of the AGBe a first workshop on the topic “Monitoring and trust” was carried out on 13 March 2021, supported by partners of the LUH-IRS, the TUBS-IGG and the ETH-TdLab. This article is concerned with the preparation work, the course itself and the knowledge gained from the workshop. It deals with the preparation work in the form of a website and a report on information of the AGBe suitable for those who have been addressed, which has meant a challenge in view of the complexity of the topic of monitoring of a deep geological repository and prior knowledge of the AGBe. Furthermore, the course of the workshop, which was carried out online due to the coronavirus pandemic, is discussed, in which the 12 members of the AGBe and 10 scientists came together. The workshop began with a brainstorming on the topic of monitoring. This was followed by two specialist lectures, in which information on deep geological disposal and monitoring as well as the possibilities and limits of monitoring and monitoring conceptions was presented. The members of the AGBe were then divided into three groups, in which the central research questions of the workshop were discussed: Does a long-term near-field monitoring contribute to trust in the safety of deep geological disposal of radioactive waste? Which aspects of monitoring conceptions could increase trust in the implementation of near-field monitoring and which do not? After the presentation of the results from the group discussion a common discussion was first carried out in the plenum, in which a picture of the sentiments within the AGBe was finally formulated. Furthermore, the knowledge from the three discussion formats of the workshop is presented in this article. This includes the characterization of information and communication with the civil society as a central aspect in relationship with monitoring and trust. Furthermore, it showed that the AGBe views the long-term monitoring of a repository as a suitable measure for gaining trust. However, which aspects of monitoring conceptions contribute significantly to trust in the safe storage of radioactive waste is less clear after this first workshop and could not be conclusively answered. The results of this workshop with the AGBe reflect a first impression in the discussion on monitoring and trust. As monitoring is a complex topic with many interfaces on repository storage and sealing concepts, repository processes and multiple physical simulations as well as on societal topics, the discussion with the AGBe on the topic of monitoring should be continued during the course of the project. Thereby, it must be taken into consideration if the first positive assesments as well as the first AGBe specific requirements regarding long-term near-field monitoring activities will change with increasing knowledge.

Multi-criteria site assessment process for candidate deep geological repository sites: Case study from the Czech Republic 

2021 ◽  
Author(s):  
Lukas Vondrovic ◽  
Jaromir Augusta ◽  
Antonin Vokal ◽  
Katerina Konopacova ◽  
Eva Popelova ◽  
...  
Keyword(s):  
Czech Republic ◽  
Assessment Process ◽  
Deep Geological Repository ◽  
Data Set ◽  
Site Assessment ◽  
The Czech Republic ◽  
Second Stage ◽  
Geological Repository

<p>The future deep geological repository for radioactive waste in the Czech Republic will be constructed in a suitable crystalline rock mass around 500 metres below the earth’s surface. The commencement of operation is planned for 2065. The current DGR development phase is devoted principally to the determination of the optimum disposal concept and the selection of the most suitable site. A total of nine potential sites have been assessed with the aim of reducing their number to four.</p><p>The data set subjected to assessment included site descriptions from the geological point of view (3D geological and hydrogeological model), and long-term site stability (seismotectonic, climate and erosion) and geomechanical data. A further assessed dataset included information on construction issues and on the evaluation of both environmental characteristics and the presence of groundwater resources. All the assessed characteristics were derived from surface-based exploration without the need for borehole drilling.</p><p>The key criteria reflected the three main areas of concern i.e. long-term and operational safety (including geological and hydrogeological indicators), technical feasibility and environmental impacts. The assessment of the sites was performed in two stages. The first stage involved the assessment of the probability of fulfilling the exclusion criteria (total 26), while the second stage involved the mutual comparison of the sites in terms of the defined key criteria (total of 13, divided into 38 indicators). The second stage involved the determination of weightings for the various criteria and indicators via the application of the SAATY method for the expert comparison of the significance of criteria. This method distinguished between relatively strongly weighted and less weighted criteria. The sites were graded with respect to the value estimation of the criteria; moreover, the grading of the sites considered various types of data.</p><p>A total of eight calculations were performed for five scenarios using various procedures for the estimation of the weightings and for data normalisation purposes. The first assessment stage indicated that all the sites fulfilled the DGR site assessment methodology requirements. The second stage, which comprised the assessment of the comparison of the site calculations (assessment grades) for each of the sites, was based on the levels of significance of the indicators and criteria and the resulting representative values for each site. The results of the subsequent comparison calculations indicated that the same four sites always occupied the first four positions with only minor variations in the order. The differences in the gradings of the four most suitable sites and the four relatively less suitable five sites ranged between 11% and 17.8% (between the fourth and fifth sites), which convincingly differentiated between the two groups of sites. One site was always in last position according to the calculations. In compliance with the assessment results, the four  sites were subsequently recommended to the Government of the Czech Republic for further follow-up research and analysis. Those sites that were not recommended for the next stage of research will continue to be considered as reserve (i.e. backup) sites.</p>

Long Term Corrosion Behaviour of Carbon Steel During Anaerobic to Aerobic Cycling Under Near-Neutral pH Saline Conditions

2010 ◽  
Author(s):  
Brent W. A. Sherar ◽  
Peter G. Keech ◽  
Zack Qin ◽  
Fraser King ◽  
David W. Shoesmith ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Focused Ion Beam ◽  
Corrosion Behaviour ◽  
Ion Beam ◽  
Cycle Number ◽  
Corrosion Rates ◽  
Anaerobic Corrosion ◽  
Film Porosity ◽  
Electrochemical Microscopy

This paper investigates the long term corrosion behaviour of pretreated carbon steel under alternating anaerobic to aerobic cycles over 238 days. Changes in steel behaviour were observed electrochemically by monitoring the corrosion potential, and calculating changes to corrosion rate from linear polarization resistance. With increasing cycle number the corrosion process becomes localized at a small number of locations, consistent with the formation of tubercles. Periods of aerobic corrosion were associated with more positive potentials (between −500 mV to −350 mV) and high corrosion rates (70 to 120 μm yr−1); whereas anaerobic corrosion yielded more negative potentials (< −650 mV) and lower corrosion rates (40 to 50 μm yr−1). Upon termination of the experiment, corrosion product deposits were characterized by several techniques: scanning electrochemical microscopy to detect morphology; focused ion beam and cross sectioning to judge film thickness and film porosity; and Raman Spectroscopy to identify iron phases.

Experimental pressure and sealing plug as part of the European DOPAS project – deep geological repository plug demonstration

Clay Minerals ◽  
2016 ◽  
Vol 51 (4) ◽  
pp. 589-601
Author(s):  
Irena Hanusová ◽  
Jiří Svoboda ◽  
Petr Večerník
Keyword(s):  
Czech Republic ◽  
Research Centre ◽  
International Project ◽  
Construction Technology ◽  
Deep Geological Repository ◽  
The Czech Republic ◽  
Geological Repository ◽  
Experimental Pressure

AbstractThe objective of the DOPAS international project is to design a sealing-plug system for deep geological repository (DGR) use, to provide detailed plans for the design of such plugs, to test the characteristics of the materials to be used and the construction technology and to install four experimental in situ plugs. The Czech experimental pressure and sealing-plug (EPSP) experiment is being conducted in a rock environment consisting of granitoids at the Josef Regional Underground Research Centre. The concept of the experiment is based primarily on the use of materials and technology available in the Czech Republic and the principal aim is to demonstrate the technical viability and functioning of a pressure-resistant plug located in a future DGR. The completion of the EPSP experiment will contribute towards both the demonstration of how sealing-plug systems behave under real underground conditions and the long-term safety of a future DGR in the Czech Republic.

Modelling Study to Evaluate Two Variants for Accessing a Deep Geological Repository From the Point of View of Long-Term Safety

2013 ◽  
Author(s):  
Andreas Poller ◽  
Paul Smith ◽  
Gerhard Mayer ◽  
Mohamed Hayek ◽  
Jürg W. Schneider ◽  
...  
Keyword(s):  
Network Flow ◽  
Flow Model ◽  
Transport Model ◽  
Point Of View ◽  
Access Route ◽  
Deep Geological Repository ◽  
Acceptable Solution ◽  
Geological Repository ◽  
Exact Position

Siting a deep geological repository for radioactive waste essentially involves two interrelated steps: deciding on an appropriate geological environment for the underground facilities and selecting a suitable location for the associated surface facility. An acceptable solution is more easily achieved if some flexibility exists for siting the surface facility, irrespective of the exact position of the underground facilities. Such flexibility is available if a ramp is used as the main access route from the surface facility to the underground facilities. Another option is to use a combination of shafts and (sub)horizontal tunnels as the main access route. Both variants include shafts for ventilation, etc. In this paper, the two variants (i) main access via ramp and (ii) main access via shaft are compared in terms of long-term safety. To this end, the entire network of underground tunnels of a deep geological repository is implemented in an analytical resistor network flow model. Radionuclide release through the tunnel system and the host rock is then calculated with a numerical network transport model, using as input the results from the flow model. The results clearly indicate that, even in case of hypothetically deficient horizontal and subhorizontal sealing elements, the choice between ramp and shaft as the main access route is irrelevant to long-term safety.

scholarly journals Microbiology of Barrier Component Analogues of a Deep Geological Repository

2021 ◽  
Author(s):  
Rachel C Beaver ◽  
Katja Engel ◽  
W. Jeffrey Binns ◽  
Josh Neufeld
Keyword(s):  
Nuclear Fuel ◽  
Selection Process ◽  
Crystalline Rock ◽  
Opalinus Clay ◽  
Rrna Gene ◽  
Deep Geological Repository ◽  
Used Nuclear Fuel ◽  
Geological Repository ◽  
Clay Formation

Canada is currently implementing a site selection process to identify a location for a deep geological repository (DGR) for the long-term storage of Canada’s used nuclear fuel, wherein used nuclear fuel bundles will be sealed inside copper-coated carbon steel containers, encased in highly compacted bentonite clay buffer boxes and sealed deep underground in a stable geosphere. Because a DGR must remain functional for a million years, there is value to examining ancient natural systems that serve as analogues for planned DGR components. Specifically, studying the microbiology of natural analogue components of a DGR is important for developing an understanding of the types of microorganisms that may be able to grow and influence the long-term stability of a DGR. This study explored the abundance, viability, and composition of microorganisms in several ancient natural analogues using a combination of cultivation and cultivation-independent approaches. Samples were obtained from the Tsukinuno bentonite deposit (Japan) that formed ~10 mya, the Opalinus Clay formation (Switzerland) that formed ~174 mya, and Canadian shield crystalline rock from Northern Ontario that formed ~2.7 bya. Analysis of 16S rRNA gene amplicons revealed that three of the ten Tsukinuno bentonite samples analyzed were dominated by putative aerobic heterotrophs and fermenting bacteria from the Actinobacteria phylum, whereas five of the Tsukinuno bentonite samples were dominated by sequences associated with putative acidophilic chemolithoautotrophs capable of sulfur reduction.

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