Effect of Binder Components on the pH of Concrete Mixture with Low pH Intended for Deep Geological Repository for Radioactive Waste in the Czech Republic

2020 ◽  
Vol 868 ◽  
pp. 15-23
Author(s):  
Radka Pernicova ◽  
David Čítek ◽  
Daniel Dobiáš ◽  
Jiří Kolisko ◽  
Tomáš Mandlík ◽  
...  

This paper deals with the development and research of low pH concrete mixtures intended for the deep geological repository for radioactive waste. Mixtures, in particular those made from materials originating in the Middle Europe, specifically Czech Republic, were designed due to the diversity of the raw materials’ properties. In this first part, a large number of cement mortars were designed, on which the effect of active ingredients (microsilica, slag) on the pH value over time were tested. From the results of the cement mortars’ pH measured after 90 days, a concrete formula was designed. A mixture with a lower proportion of cement and a higher proportion of microsilica seems to be the best. The slag serves only as a supplement in the place value of several weight percent of the total binder volume. Also, the control measurements of basic material characteristics, such as volumetric mass density and compressive strength were performed on these mixtures.

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):  
Václava Havlová

ÚJV Řež, a.s. as a company with a long term experience in radioactive waste management (RWM) has been running a comprehensive research programme, supporting development of deep geological repository (DGR) in the Czech Republic. Recently ÚJV Řež, a.s. research has focused on the different aspects of safety functions that DGR barriers should provide. Moreover, the research has also recently paid strong attention to real conditions that can be present in DGR (anaerobic reducing conditions, increased T due to heat generation by radioactive waste, contact of different materials within repository, real scale of the rock massive etc.). Both types of experiments, laboratory and in-situ experiments in underground laboratories, were included in the research programme. The presentation gives a brief overview of experimental trends, being conducted for materials and conditions, concerned in Czech repository concept.


Energy Policy ◽  
2017 ◽  
Vol 105 ◽  
pp. 458-466 ◽  
Author(s):  
Petr Ocelík ◽  
Jan Osička ◽  
Veronika Zapletalová ◽  
Filip Černoch ◽  
Břetislav Dančák

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 ◽  
Author(s):  
Lukas Vondrovic ◽  
Jaromir Augusta ◽  
Antonin Vokal ◽  
Katerina Konopacova ◽  
Eva Popelova ◽  
...  

<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>


Clay Minerals ◽  
2016 ◽  
Vol 51 (4) ◽  
pp. 589-601
Author(s):  
Irena Hanusová ◽  
Jiří Svoboda ◽  
Petr Večerník

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.


2014 ◽  
Vol 923 ◽  
pp. 161-164
Author(s):  
Šárka Keprdová ◽  
Tomáš Melichar ◽  
Vit Cerný

This paper presents the results of research focused on the modification of composition of the polymer-cement mortars. The use of these materials is quite wide. The greatest use can be found in the production of reinforced concrete repair materials. Specifically, the article analyzes problems of lightweight aggregate effect on the resistance of polymer-cement mortars to extremely high temperatures. The link is particularly evident with the risk of fire. Attention was given to the two different types of aggregates - from primary raw materials (Liapor) and alternative sources of raw materials (fly ash aggloporite). The study was carried out by the laboratory analyzing the basic material characteristics of prepared samples which were exposed to temperatures up to 1200 ° C.


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