Hydraulic Conductance of the EDZ around Underground Structures of a Geological Repository for Radioactive Waste

Author(s):  
A. Alcolea Rodriguez ◽  
U. Kuhlmann
2019 ◽  
Vol 133 ◽  
pp. 02005
Author(s):  
Markéta Camfrlová

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.


Author(s):  
Kazumi Kitayama

The programme for disposal of radioactive waste in Japan is now moving ahead on a number of fronts. On the regulatory side, responsibility for TRU waste disposal has been assigned to NUMO and guidelines for the safety goals for disposal of LLW have been published. NUMO, as the implementer for the deep geological disposal programme, has been developing the special tools for project management that are needed as a result of the decision to adopt a volunteering approach to siting. NUMO is also building up the technical infrastructure for flexible tailoring of site characterisation, repository design and the associated safety assessment to the conditions found in any volunteer site. This work requires openness and transparency in decision-making but, as several sites may need to be investigated in parallel, particular emphasis is placed on operational practicality.


Author(s):  
Morimasa Naito ◽  
Hirokazu Kishi ◽  
Naomi Fukuoka ◽  
Tsutomu Yamada ◽  
Hideaki Ishida

As an alternative grouting material for the geological repository of long-lived radioactive waste, the “Superfine Spherical silica Grout” (SFSG) material is developed using a fine spherical silica and a fine calcium hydroxide. The developed SFSG material takes an advantage of its smaller particle size distribution (max. ∼1 micron or less) than those of the cementitious materials, and also provides a low alkaline environment so as to reduce unfavorable effects on the long-term performance of geological disposal system. The SFSG is a mixture of the “super fine silica powder”, the superfine calcium hydroxide and additives such as superplasticizer. Presently, the mixture being investigated for grouting materials is focused on water/binder ratio (W/B) of 1.2. Some preliminary laboratory experiments were carried out to characterize its fundamental properties from the viewpoint of practical use for geological disposal, which is required to be equivalent with the conventional cementitious materials in terms of penetrability, strength, pH performance and workability. From a series of experiments, it was concluded that SFSG is expected to become an alternative grouting material for a geological repository.


2021 ◽  
Vol 1 ◽  
pp. 271-273
Author(s):  
Johann Arne Othmer ◽  
Karl-Heinz Lux ◽  
Ralf Wolters ◽  
Jörg Feierabend

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.


2021 ◽  
Vol 1 ◽  
pp. 195-196
Author(s):  
Stephan Hotzel

Abstract. Most, if not all, national programmes for radioactive waste management pledge their overall commitment to safety or – in the case of radioactive waste disposal – to long-term safety. Therefore, it may be somewhat surprising to find that the term “safety” is hardly defined in these programs. The same holds for some of the core international guidance literature on the deep geological repository (DGR) “safety case” concept. With respect to stakeholder concern over the safety of geological disposal, it seems, however, advisable to seek common ground in the understanding of the idea of “safety”. Hotzel and Schröder (2018) reviewed the most relevant international guidance literature for explicitly or implicitly provided definitions of “safety” in the context of radioactive waste disposal. Based on this study – and on the finding that a practical, useful-for-all definition of “safety” is not provided in the scanned literature – they developed a tentative dictionary-style definition of “safety” that is suitable for everyday use in the DGR context. In the current contribution I embed, expand and update the 2018 study at both ends: As an enhanced introduction to the 2018 study, I lay out a basic concept of “sound” glossary definitions, namely glossary definitions being both practical and correct (and what this means). The thesis is that sound glossary definitions can facilitate mutual understanding between different stakeholder groups. As an update to the actual proposal for the definition of “safety” from the Hotzel and Schröder (2018) paper, that was presented and discussed at the Waste Management Conference 2018, I review the latest international guidance literature and the stakeholder concerns raised at the 2018 conference in order to present a revised definition. As a seed of discussion, it may help to eventually expose possible mismatches in the base assumptions of safety experts and other stakeholders and thereby support meaningful communication.


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