Enhancing Safety Of Nuclear Waste Disposal By Exploiting Regional Groundwater Flow: The Recharge Area Concept

Töth, J.; Sheng, G.

doi:10.1007/s100400050252

Cited by 18 publications

(14 citation statements)

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“…Furthermore, the variable density models (Figures 5 and 6) indicate that it is possible for saline water to occur close to the ground surface in discharge areas where groundwater movement is generally upward, and freshwater to recharge to great depths in recharge areas where movement is downward. This statement is in agreement with findings from modelling studies by Tóth and Sheng (1996), Ophori (1999) and Sheng and Tóth (2000), and is corroborated by field data from Fritz and Reardon (1979), Gascoyne et al (1987) and Davisson and Criss (1993).…”

Section: Generalsupporting

confidence: 92%

“…These long travel times also have been verified independently by Nakka and Chan (1994), using analytical techniques. For a vault in a regional recharge area, Tóth and Sheng (1996) and Sheng and Tóth (2000) reported that the presence of a fracture zone may indeed increase the travel time over and above that in which no fracture zone is present. It is noteworthy that in areas such as the WRA with long travel times, changes in the flow field that may result from future transient effects (e.g.…”

Section: Pathways and Travel Time Of Groundwater From The Location Ofmentioning

confidence: 97%

“…The vault was placed near LD1 in order to analyse possible consequences that an existing fracture zone was missed out in error during field investigation to characterize an actual waste disposal site. This placement of the vault made it a regional discharge-area vault, rather than a recharge-area vault, the significance of which is closely related to minimum travel time as discussed by Tóth and Sheng (1996), and Sheng and Tóth (2000). The initial data were updated from field investigations conducted at the WRA and URL between 1985 and 1994.…”

Section: Introductionmentioning

confidence: 95%

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A simulation of large‐scale groundwater flow and travel time in a fractured rock environment for waste disposal purposes

Ophori

2004

Hydrological Processes

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Abstract:Two-dimensional regional groundwater flow was simulated based on a conceptual model of low-permeability crystalline rocks of the Whiteshell Research Area (WRA) in south-eastern Manitoba. The conceptual model consists of fracture zones that strike in different directions and dip at various angles in the background rock mass. The thickness and hydraulic properties of the fracture zones in the conceptual model were varied as were the fluid properties and the boundary conditions of the groundwater flow system. The effects of these variations on the groundwater flow pattern and on the convective travel time along pathways from a hypothetical disposal vault at 500 m depth to discharge locations at the ground surface were evaluated. The vault was located in the regional discharge area of the groundwater system. A homogeneous conceptual model of the WRA, having only freshwater flow, formed a groundwater flow pattern with a regional flow system. Local flow systems developed increasingly with the introduction of fracture zones 20 m and 3 m thick, and depth-dependent fluid density. This indicates a reduction in groundwater residence time by fracture zones and fluid density. Flow pathways were analysed using both a stream-function and a particle-tracking technique. The pathways and their lengths from the location of the vault to the surface varied spatially according to the flow patterns. The minimum travel time along these pathways was less than 150 000 and greater than 4 000 000 years in models with and without fracture zones, respectively, indicating that the presence of fracture zones was the major controlling factor. A precise knowledge and refinement of conceptual model parameters is necessary during site selection for waste disposal purposes.

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Section: Generalsupporting

confidence: 92%

Section: Pathways and Travel Time Of Groundwater From The Location Ofmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 95%

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A simulation of large‐scale groundwater flow and travel time in a fractured rock environment for waste disposal purposes

Ophori

2004

Hydrological Processes

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“…The hydraulic head at the ground surface is specified as the topographic elevation, with the sides and bottom specified as noflux boundaries, as it is taken that the water table location is generally subdued replica of the topography in the shield environment [25,28]. Shield brine is assumed to be initially located from 500 m below sea level to the base of the domain ðC ¼ C 0 Þ and densitydependent brine migration is simulated for 10,000 years to estimate the distribution of brine at the present.…”

Section: Numerical Modeling and Computational Performancementioning

confidence: 99%

Application of implicit sub-time stepping to simulate flow and transport in fractured porous media

Park

Sudicky

Panday

et al. 2008

Advances in Water Resources

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“…The most common one is probably particle tracking. A collection of particle tracks gives a set of transit times from which the transit-time distribution is calculated (Tóth 1996; Nationale Genossenschaft für die Lagerung Radioaktiver Abfälle 1997; Oliveira and Baptista 1997). A disadvantage of the method is that the results are quite sensitive to the chosen path lines.…”

Section: Introductionmentioning

confidence: 99%

Direct simulation of groundwater transit-time distributions using the reservoir theory

Etcheverry

Perrochet

2000

Hydrogeology Journal

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Groundwater transit times are of interest for the management of water resources, assessment of pollution from non-point sources, and quantitative dating of groundwaters by the use of environmental isotopes. The age of water is the time water has spent in an aquifer since it has entered the system, whereas the transit time is the age of water as it exits the system. Water at the outlet of an aquifer is a mixture of water elements with different transit times, as a consequence of the different flow-line lengths. In this paper, transit-time distributions are calculated by coupling two existing methods, the reservoir theory and a recent age-simulation method. Based on the derivation of the cumulative age distribution over the whole domain, the approach accounts for the whole hydrogeological framework. The method is tested using an analytical example and its applicability illustrated for a regional layered aquifer. Results show the asymmetry and multimodality of the transit-time distribution even in advection-only conditions, due to the aquifer geometry and to the velocity-field heterogeneity.RØsumØ Les temps de transit des eaux souterraines sont intØressants à connaître pour gØrer l'Øvaluation des ressources en eau dans le cas de pollution à partir de sources non ponctuelles, et aussi pour dater quantitativement les eaux souterraines au moyen des isotopes du milieu. L'âge de l'eau est le temps qu'elle a passØ dans un aquifre depuis qu'elle est entrØe dans le systme, alors que le temps de transit est l'âge de l'eau au moment o elle quitte le systme. L'eau à la sortie d'un aquifre est un mØlange d'eaux possØdant diffØrents temps de transit, du fait des longueurs diffØ-rentes des lignes de courant suivies. Dans ce papier, les distributions des temps de transit sont calculØes en couplant deux mØthodes, la thØorie du rØservoir et une mØthode rØcente de simulation des âges. BasØe sur la dØrivation de la distribution cumulØes des âges sur tout le domaine, l'approche prend en compte le cadre hydrogØologique dans son ensemble. La mØthode est testØe sur un exemple analytique et son applicabilitØ est illustrØe pour un aquifre stratifiØ rØgional. Les rØsultats montrent l'asymØtrie et la plurimodalitØ de la distribution des temps de transit mme dans des conditions uniquement d'advection, à cause de la gØomØtrie de l'aquifre et de l'hØtØrogØnØitØ du champ des vitesses.Resumen El estudio de los tiempos de trµnsito del agua subterrµnea es muy til para (1) la gestión de los recursos de agua frente a la contaminación por focos no puntuales, y (2) la datación de aguas mediante isó-topos ambientales. La edad de un agua subterrµnea es el tiempo que Østa ha permanecido en el acuífero contada desde el momento de su entrada, mientras que el tiempo de trµnsito corresponde a la edad del agua en el momento en que abandona el sistema. En el punto de descarga en realidad se encuentra una mezcla de aguas con distintos tiempos de trµnsito, debido a la yuxtaposición de líneas de flujo con diferentes recorridos. En este artículo se calcula...

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Enhancing Safety Of Nuclear Waste Disposal By Exploiting Regional Groundwater Flow: The Recharge Area Concept

Cited by 18 publications

References 0 publications

A simulation of large‐scale groundwater flow and travel time in a fractured rock environment for waste disposal purposes

A simulation of large‐scale groundwater flow and travel time in a fractured rock environment for waste disposal purposes

Application of implicit sub-time stepping to simulate flow and transport in fractured porous media

Direct simulation of groundwater transit-time distributions using the reservoir theory

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