Recent Advances in Repository Seal Materials

1981 ◽  
Vol 11 ◽  
Author(s):  
D.M. Roy ◽  
F.L. Burns
Keyword(s):  
Fluid Flow ◽  
Radioactive Waste ◽  
Host Rock ◽  
Recent Advances

One long-term solution proposed for isolating radioactive waste from the biosphere is containment in underground geologic repositories. A requirement for this procedure is that most penetrations into the repository region be sealed following emplacement of the waste. The general requirements of repository seal materials and the seal system are that these potential pathways to the biosphere be sealed adequately to prevent a) excess fluid flow into the repository and b) radionuclides in the waste from reaching the biosphere in quantities in excess of acceptable levels. For boreholes, shafts and tunnels it is generally recommended that in the post-closure phase, the permeability of sealed boreholes and shafts be approximately the same as the host rock or the aquitards in the zones where aquitards are intersected.

scholarly journals Assessment of Permian Zubers as the Host Rock for Deep Geological Disposal

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2239
Author(s):  
Leszek Lankof
Keyword(s):  
Radioactive Waste ◽  
Rock Salt ◽  
Host Rock ◽  
Nuclear Power ◽  
Spent Nuclear Fuel ◽  
Renewable Energy Sources ◽  
Geological Disposal ◽  
Lithostratigraphic Units ◽  
Deep Geological Disposal

Together with renewable energy sources, nuclear power represents an important contribution to a sustainable energy mix in many countries and has an important impact on sustainable development. Nuclear energy production is also a source of high-level radioactive waste (HLW) and spent nuclear fuel (SNF), which require special concern. Disposal in deep geological formations is one of the solutions for the long-term management of HLW and SNF. It requires the development of a concept ensuring long-term safe isolation of waste and its validation applying the safety case methodology, which is a formal compilation of evidence, analyses and arguments that quantify and justify a claim that the repository will be safe. The results of laboratory testing of a potential repository host rock are an important component of the evidence that helps in the safety assessment of the deep geological disposal concept. This paper presents results of research focused on the physical, geomechanical and sorption properties of the Brown and Red Zuber unit rocks from the Kłodawa Salt Mine in Poland, which together with rock salt are an important component of Polish salt domes. The Brown and Red Zubers are typical evaporite lithostratigraphic units for the Polish part of the Zechstein Basin. They consist of halite (15–85%) and water-insoluble minerals, such as anhydrite, clay minerals, carbonates, quartz and feldspar, which occurred in varying proportions in the tested samples. The properties of the zuber rocks have been compared with those of rock salt, which is considered a suitable host rock for deep geological disposal of radioactive waste.

Project Opalinus Clay – Geoscientific Basis for the Demonstration of Feasibility of Disposal (Entsorgungsnachweis) for SF, Vitrified HLW and Long-Lived ILW in Switzerland

2003 ◽  
Vol 807 ◽  
Author(s):  
A. Gautschi ◽  
A. Lambert ◽  
P. Zuidema
Keyword(s):  
Radioactive Waste ◽  
Host Rock ◽  
Opalinus Clay ◽  
Geological Environment ◽  
Deep Geological Repository ◽  
Geological Repository ◽  
National Cooperative

ABSTRACTNagra - the Swiss National Cooperative for the Disposal of Radioactive Waste - has completed a study to determine the suitability of Opalinus Clay as a host rock for a SF/HLW/ILW repository in a potential siting area (reference repository site) in the Zürcher Weinland in northeastern Switzerland. Geoscientific information has been used to a wide extent for the demonstration of siting and engineering feasibility, and for the demonstration of long-term safety. It is shown that the selected area in the Zürcher Weinland fulfils the fundamental requirements placed on a siting area for a deep geological repository and that, in terms of the Opalinus Clay host rock option, the geological environment is advantageous.

The long-term cement studies project: the UK contribution to model development and testing

2012 ◽  
Vol 76 (8) ◽  
pp. 3445-3455 ◽  
Author(s):  
C. E. Watson ◽  
D. Savage ◽  
J. Wilson ◽  
C. Walker ◽  
S. J. Benbow
Keyword(s):  
Radioactive Waste ◽  
Host Rock ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Spatial Scales ◽  
Radioactive Waste Disposal ◽  
In Situ Tests ◽  
Rock Interaction ◽  
Future System

AbstractThe international long-term cement studies (LCS) project aims to increase the understanding of the behaviour of cement within a radioactive waste disposal system and how hyper-alkaline leachates may interact with host rock. Such an understanding enables confident, robust and safety-relevant statements to be made concerning future system behaviour, irrespective of host rock, engineered barrier system, or waste type. The LCS project involves laboratory experiments, in situ tests and numerical modelling to address these issues. The agencies participating are Nagra (Switzerland), JAEA (Japan), the Nuclear Decommissioning Authority, Radioactive Waste Mangement Directorate (UK), Posiva (Finland) and SKB (Sweden).Project activities have included: the development of conceptual and theoretical models of cement–rock interaction; testing of numerical models against data from laboratory experiments and industrial and natural analogues of cement–rock reaction; and the synthesis and incorporation of performance assessment (PA) relevant data from analogue studies. Key threads running through these studies include an analysis of issues relating to upscaling of processes and data to the greater temporal and spatial scales relevant to PA, and investigations of modelling the changes in physical properties that accompany geochemical reaction. Here we present examples of the results from model test cases, highlighting the important issues that have arisen.

An overview of near-field evolution research in support of the UK geological disposal programme

2012 ◽  
Vol 76 (8) ◽  
pp. 2995-3001 ◽  
Author(s):  
T. M. Beattie ◽  
S. J. Williams
Keyword(s):  
Radioactive Waste ◽  
Host Rock ◽  
Near Field ◽  
Radioactive Decay ◽  
Geological Disposal ◽  
Nuclear Decommissioning ◽  
Disposal Facility ◽  
Engineered Barriers ◽  
The Uk

AbstractThe near field, together with the containment and isolation provided by the geosphere, contributes to the long-term safety provided by a geological disposal facility (GDF) after closure. The different engineered barriers can prevent or limit the release of radionuclides and their migration to the undisturbed host rock or geosphere and are expected to fulfil their post-closure safety functions for many thousands to hundreds of thousands of years. They will continue to contribute to containment after their eventual degradation when there would no longer be confidence that they would continue to fulfil all of their safety functions in their totality. By that time, significant radioactive decay will have occurred, substantially reducing the hazard associated with the wastes. Therefore, demonstration of long-term safety requires an understanding of the evolution of the engineered barriers and the consequences for the generic safety functions that the different barriers provide. This paper provides an overview of the research of the Nuclear Decommissioning Authority Radioactive Waste Management Directorate into the evolution of the near field of a GDF.

EBS Behaviour Immediately After Repository Closure in a Clay Host Rock: The HE-E Experiment (Mont Terri URL)

2011 ◽  
Author(s):  
Irina Gaus ◽  
Klaus Wieczorek ◽  
Juan Carlos Mayor ◽  
Thomas Trick ◽  
Jose´-Luis Garcia` Sin˜eriz ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Host Rock ◽  
Large Scale ◽  
Process Models ◽  
Research Activities ◽  
Hydraulic Behaviour ◽  
Validation Experiment ◽  
Engineered Barrier ◽  
Mont Terri

The evolution of the engineered barrier system (EBS) of geological repositories for radioactive waste has been the subject of many research programmes during the last decade. The emphasis of the research activities was on the elaboration of a detailed understanding of the complex thermo-hydro-mechanical-chemical processes, which are expected to evolve in the early post closure period in the near field. It is important to understand the coupled THM-C processes and their evolution occurring in the EBS during the early post-closure phase so it can be confirmed that the safety functions will be fulfilled. Especially, it needs to be ensured that interactions during the resaturation phase (heat pulse, gas generation, non-uniform water uptake from the host rock) do not affect the performance of the EBS in terms of its safety-relevant parameters (e.g. swelling pressure, hydraulic conductivity, diffusivity). The 7th Framework PEBS project (Long Term Performance of Engineered Barrier Systems) aims at providing in depth process understanding for constraining the conceptual and parametric uncertainties in the context of long-term safety assessment. As part of the PEBS project a series of laboratory and URL experiments are envisaged to describe the EBS behaviour after repository closure when resaturation is taking place. In this paper the very early post-closure period is targeted when the EBS is subjected to high temperatures and unsaturated conditions with a low but increasing moisture content. So far the detailed thermo-hydraulic behaviour of a bentonite EBS in a clay host rock has not been evaluated at a large scale in response to temperatures of up to 140°C at the canister surface, produced by HLW (and spent fuel), as anticipated in some of the designs considered. Furthermore, earlier THM experiments have shown that upscaling of thermal conductivity and its dependency on water content and/or humidity from the laboratory scale to a field scale needs further attention. This early post-closure thermal behaviour will be elucidated by the HE-E experiment, a 1:2 scale heating experiment setup at the Mont Terri rock laboratory, that started in June 2011. It will characterise in detail the thermal conductivity at a large scale in both pure bentonite as well as a bentonite-sand mixture, and in the Opalinus Clay host rock. The HE-E experiment is especially designed as a model validation experiment at the large scale and a modelling programme was launched in parallel to the different experimental steps. Scoping calculations were run to help the experimental design and prediction exercises taking the final design into account are foreseen. Calibration and prediction/validation will follow making use of the obtained THM dataset. This benchmarking of THM process models and codes should enhance confidence in the predictive capability of the recently developed numerical tools. It is the ultimate aim to be able to extrapolate the key parameters that might influence the fulfilment of the safety functions defined for the long term steady state.

scholarly journals Applications, challenges, and needs for employing synthetic biology beyond the lab

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sierra M. Brooks ◽  
Hal S. Alper
Keyword(s):  
Synthetic Biology ◽  
Great Promise ◽  
Long Term Storage ◽  
Autonomous Function ◽  
Recent Advances ◽  
Resource Limited ◽  
Major Application ◽  
Further Development ◽  
Probiotic Delivery

AbstractSynthetic biology holds great promise for addressing global needs. However, most current developments are not immediately translatable to ‘outside-the-lab’ scenarios that differ from controlled laboratory settings. Challenges include enabling long-term storage stability as well as operating in resource-limited and off-the-grid scenarios using autonomous function. Here we analyze recent advances in developing synthetic biological platforms for outside-the-lab scenarios with a focus on three major application spaces: bioproduction, biosensing, and closed-loop therapeutic and probiotic delivery. Across the Perspective, we highlight recent advances, areas for further development, possibilities for future applications, and the needs for innovation at the interface of other disciplines.

An Assessment of the Long-Term Durability of Concrete in Radioactive Waste Repositories

1985 ◽  
Vol 50 ◽  
Author(s):  
A. Atkinson ◽  
D. J. Goult ◽  
J. A. Hearne
Keyword(s):  
Reinforced Concrete ◽  
Radioactive Waste ◽  
Concrete Slab ◽  
Laboratory Studies ◽  
Preliminary Assessment ◽  
Reinforced Concrete Slab ◽  
Radioactive Waste Repositories ◽  
Waste Repositories ◽  
Durability Of Concrete

AbstractA preliminary assessment of the long-term durability of concrete in a repository sited in clay is presented. The assessment is based on recorded experience of concrete structures and both field and laboratory studies. It is also supported by results of the examination of a concrete sample which had been buried in clay for 43 years.The enoineering lifetime of a 1 m thick reinforced concrete slab, with one face in contact with clay, and the way in which pH in the repository as a whole is likely to vary with time have both been estimated from available data. The estimates indicate that engineering lifetimes of about 103 years are expected (providing that sulphate resisting cement is used) and that pH is likely to remain above 10.5 for about 106 years.

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