scholarly journals Far-field transport modelling for a repository in the Boom Clay in the Netherlands

2016 ◽  
Vol 95 (3) ◽  
pp. 337-347 ◽  
Author(s):  
J.R. Valstar ◽  
N. Goorden
Keyword(s):  
The Netherlands ◽  
Radioactive Waste ◽  
Groundwater Flow ◽  
Flow Patterns ◽  
Groundwater Model ◽  
Travel Times ◽  
Boom Clay ◽  
Disposal Facility ◽  
Geological Formation ◽  
Geological Formations

AbstractA groundwater model was set up to study far-field transport for the potential of a radioactive waste repository the Boom Clay in the Netherlands. The existing national groundwater model, the Netherlands Hydrological Instrument, was extended in the vertical direction to include geological formation up to and beyond the Boom Clay. As the amount of hydrogeological data in the deeper subsurface is limited, simplifications in the model schematisation were necessary. Moreover, nationwide data about the tops and bottoms of many of the deeper geological formations and their members are lacking and required interpolation. Finally, values for hydrogeological parameters, such as porosity and hydraulic conductivity, are also lacking for the deeper formations. These values were estimated using relationships with depth and lithology. Moreover, no quantitative data about heterogeneity within the deeper geological formations or its members were available.In the Dutch research programme on the geological disposal of radioactive waste (OPERA), the post-closure safety of a generic repository is assessed in either Boom Clay or rock salt. Disposal of Dutch radioactive waste is not foreseen in the next decades and a choice of host rock has not been made. In the early, conceptual phase of the radioactive waste disposal process in the Netherlands no potential repository locations were selected and a groundwater flow model for the entire Netherlands was build. As a starting point a geological disposal facility is assumed to be present at a depth of at least 500 m within a Boom Clay formation of 100 m in order to be able to make an assessment of post-closure safety with this geological formation in a disposal concept. With these assumptions, a general idea of potential flow patterns has been obtained and broken down into pathline trajectories. These trajectories were calculated to achieve input for the potential transport of radioactive isotopes (radionuclides) from this waste in the Netherlands after the closure of a disposal facility in Boom Clay.The groundwater flow patterns in the deeper subsurface strongly resemble the larger scale flow patterns in the shallow subsurface, with flow from infiltration areas in the east and the south of the Netherlands towards to seepage areas of the polders in the west and the northern part of the country or towards the river valleys of the Rhine and IJssel. Groundwater flow velocities, however, are much lower in the deeper part of the model and consequently travel times are much larger. The conservative travel times from the pathlines range from a few 1000 years to more than 10,000,000 years depending on the location for the repository. Longer travel times are obtained for locations with a downward groundwater flow in the Boom Clay.Because of the simplifications in the model schematisation and the uncertainty in the model parameters, the present results should only be considered as a first indication. Moreover, the model could not be validated due to a lack of validation data. However, the insight gained with the model may help to design a data collection strategy for dedicated model validation, such as measuring the hydraulic gradient over the Boom Clay to validate downward flow in the Boom Clay to obtain the necessary data for a post-closure safety assessment.

The Belgian Demonstration Programme for the Disposal of High-Level and Long-Lived Radioactive Waste

2006 ◽  
Vol 932 ◽  
Author(s):  
Bernier Frédéric ◽  
Demarche Marc ◽  
Bel Johan
Keyword(s):  
Radioactive Waste ◽  
Thermal Load ◽  
Large Scale ◽  
Mechanical Response ◽  
Boom Clay ◽  
Geological Formation ◽  
Important Input ◽  
Clay Layers ◽  
High Level ◽  
Large Scale Tests

ABSTRACTThe EIG EURIDICE is responsible for performing large-scale tests, technical demonstrations and experiments so as to assess the feasibility of a final disposal of vitrified radioactive waste in deep clay layers. This programme is part of the Belgian Research and Development programme managed by ONDRAF/NIRAS. The research infrastructure includes the Underground Research Facilities HADES (URF HADES) in the Boom Clay geological formation and surface facilities. The achievements of the demonstration programme are the demonstration of the construction of shafts and galleries at industrial scale, the characterisation of the hydro-mechanical response of the host rock, and the “OPHELIE mock-up” a large scale hydration test under thermal load of pre-fabricated bentonite blocks. The future works will consist mainly in the realisation of the “PRACLAY experiments” including a large scale heater test. The large scale heater test has to demonstrate that Boom Clay is suitable, in terms of performance of the disposal system, to undergo the thermal load induced by the vitrified waste. The combined effect of the excavation and the thermal load will be investigated. A long term (more than 10 years) large scale heater test would be representative of the most penalizing conditions that could be encountered in the real disposal. The results of this test will constitute an important input for the Safety and Feasibility Cases 1 (SFC-1, 2013) and 2 (SFC-2, 2020).

scholarly journals MODELLING OF COUPLED GROUNDWATER FLOW AND RADIONUCLIDE TRANSPORT IN CRYSTALLINE BASEMENT USING FEFLOW 5.0

2006 ◽  
Vol 14 (2) ◽  
pp. 101-112 ◽  
Author(s):  
Vaidotė Jakimavičiūtė-Maselienė ◽  
Jonas Mažeika ◽  
Rimantas Petrošius
Keyword(s):  
Radioactive Waste ◽  
Groundwater Flow ◽  
Spent Nuclear Fuel ◽  
Computer Code ◽  
Crystalline Basement ◽  
Transport Modelling ◽  
Model Case ◽  
Damaged Zone ◽  
Dose Constraint ◽  
Geological Formations

The strategy of radioactive waste management of Lithuania provides for evaluating the possibilities of disposal of spent nuclear fuel and long‐lived radioactive waste originated from Ignalina NPP in deep geological formations. The initial studies performed in Lithuania during 2001–2004 focused on screening of all potentially prospective geological formations as host formations. Since most information is available on crystalline basement, this formation was selected for the model case studies. Taking into account the assumptions (canister defect scenario proposed by Swedish experts and evaluated by LEI experts), groundwater flow and radionuclide (iodine‐129 as mobile and long‐lived one) transport modelling using computer code FEFLOW was performed according to geosphere conditions and parameters characteristic of the southern part of Lithuania (0,8×0,6×0,52 km far‐field block). The upward groundwater flow through defected canister located in tectonically damaged zone was simulated. The main results of calculations are the following: in the case of upward groundwater flow, the maximum I‐129 volumetric activity in single tectonic fracture above defected canister will not exceed 1 Bq/1, and in the active water exchange zone, it is close to 10−2 Bq/l. These figures show that doses obtained by human recipient via aquatic pathway should be below the dose constraint (0,2 mSv/y). More complicated scenarios and assumptions should be investigated in future studies.

scholarly journals Assessment of Requirements to the Geological Environment for the Subsoil Siting of a Radioactive Waste Disposal Facility in Deep Geological Formations

2021 ◽  
Vol 15 (2) ◽  
pp. 90-98
Author(s):  
A. Yu. Ozerskiy ◽  
Keyword(s):  
Radioactive Waste ◽  
Waste Disposal ◽  
Radioactive Waste Disposal ◽  
Geological Environment ◽  
Disposal Facility ◽  
Geological Formations ◽  
Geological Research

The paper analyzes the structure and the contents of main regulations on the subsoil siting of deep geological radioactive waste disposal facility which was done based on the geological research performed to assess the “Yeniseiskiy” site in the Krasnoyarsk Territory. It also discusses some specific inconsistencies found in different documents, as well as ambiguities and inaccuracies in their content. The paper provides some recommendations on their upgrading.

Groundwater flow systems analysis on a regional and nation-wide scale in the Netherlands; the use of flow systems analysis in wetland management

1995 ◽  
Vol 31 (8) ◽  
pp. 375-378 ◽  
Author(s):  
F. H. Kloosterman ◽  
R. J. Stuurman ◽  
R. van der Meijden
Keyword(s):  
The Netherlands ◽  
Groundwater Flow ◽  
Systems Analysis ◽  
System Analysis ◽  
Drainage Basin ◽  
Flow System ◽  
Wetland Management ◽  
Groundwater Flow Systems ◽  
Flow Systems ◽  
Strong Relation

The project “National Groundwater Flow System Analysis” in The Netherlands was initiated in 1991 and will last until 1995. Financed by three Dutch Ministries, the project aims at the mapping of the regional groundwater flow systems to support policy makers at national levels and water/nature resources management. Much emphasis is put on biotic aspects such as the relation between groundwater and patterns in vegetation. The results are used in a detailed flow system analysis of the eco-hydrological valuable drainage basin of the brooks Beerze and Reusel in the southern parts of the country. In this study vegetation patterns and hydrological situations were analyzed in present and in historical settings to unravel the changes in the last decades leading to severe deterioration of habitats and wetlands. Historical data on flora from the beginning of this century on the basis of km-grid cells show a strong relation with the historical exfiltration areas where deep alkaline groundwaters rich in calcium-carbonate emerged. Agriculture and man-made changes to the natural drainage systems have led to diminishing nature values. Combining a sound understanding of the groundwater flow systems and the changes in the last decades produced a number of practical and viable measures to restore historical wetland settings and to preserve existing ones.

scholarly journals Measurement on Diffusion Coefficients and Isotope Fractionation Factors by a Through-Diffusion Experiment

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 208
Author(s):  
Takuma Hasegawa ◽  
Kotaro Nakata ◽  
Rhys Gwynne
Keyword(s):  
Groundwater Flow ◽  
Diffusion Coefficients ◽  
Isotope Fractionation ◽  
Free Water ◽  
Effective Porosity ◽  
Diffusion Experiment ◽  
Fractionation Factor ◽  
Through Diffusion ◽  
Geological Formations ◽  
Fractionation Factors

For radioactive waste disposal, it is important that local groundwater flow is slow as groundwater flow is the main transport medium for radioactive nuclides in geological formations. When the groundwater flow is very slow, diffusion is the dominant transport mechanism (diffusion-dominant domain). Key pieces of evidence indicating a diffusion-dominant domain are the separation of components and the fractionation of isotopes by diffusion. To prove this, it is necessary to investigate the different diffusion coefficients for each component and the related stable isotope fractionation factors. Thus, in this study, through-diffusion and effective-porosity experiments were conducted on selected artificial materials and natural rocks. We also undertook measurements relating to the isotope fractionation factors of Cl and Br isotopes for natural samples. For natural rock samples, the diffusion coefficients of water isotopes (HDO and H218O) were three to four times higher than those of monovalent anions (Cl−, Br- and NO3−), and the isotope fractionation factor of 37Cl (1.0017–1.0021) was slightly higher than that of free water. It was experimentally confirmed that the isotope fractionation factor of 81Br was approximately 1.0007–1.0010, which is equivalent to that of free water. The enrichment factor of 81Br was almost half that of 37Cl. The effective porosity ratios of HDO and Cl were slightly different, but the difference was not significant compared to the ratio of their diffusion coefficients. As a result, component separation was dominated by diffusion. For artificial samples, the diffusion coefficients and effective porosities of HDO and Cl were almost the same; it was thus difficult to assess the component separation by diffusion. However, isotope fractionation of Cl and Br was confirmed using a through-diffusion experiment. The results show that HDO and Cl separation and isotope fractionation of Cl and Br can be expected in diffusion-dominant domains in geological formations.

Groundwater flow patterns in the vicinity of underground openings in unsaturated rock—Comment

1992 ◽  
Vol 138 (3-4) ◽  
pp. 599-601 ◽  
Author(s):  
P.W. Ford ◽  
J.R. Philip ◽  
J.H. Knight
Keyword(s):  
Groundwater Flow ◽  
Flow Patterns ◽  
Underground Openings

A hydrochemical and isotopic case study around a near surface radioactive waste disposal

2007 ◽  
Vol 95 (1) ◽  
Author(s):  
Zs. Szántó ◽  
É. Svingor ◽  
I. Futó ◽  
L. Palcsu ◽  
M. Molnár ◽  
...  
Keyword(s):  
Radioactive Waste ◽  
Waste Treatment ◽  
Radioactive Waste Disposal ◽  
Ion Chemistry ◽  
Continuous Transition ◽  
Near Surface ◽  
Disposal Facility ◽  
Treatment And Disposal ◽  
Site Characterisation

As part of the site characterisation program for the near surface radioactive waste treatment and disposal facility (RWTDF) at Püspökszilágy, Hungary, water quality and environmental isotope investigations have been carried out. Water samples for major ion chemistry, tritium,The chemical composition of groundwaters presented a continuous transition from waters situated on one side to waters on the top and on the other slope of the disposal suggesting the mixing of the three hydrochemical “endmembers”.Most of δ

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