Chapter 5 Modelling radionuclide transport in the geological environment: a case study from the field of radioactive waste disposal

Alexander, W. Russell; Smith, Paul A.; McKinley, Ian G.

doi:10.1016/s1569-4860(03)80061-x

Cited by 21 publications

(4 citation statements)

References 25 publications

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“…One critical application is the long-term safety assessment of nuclear waste repositories where high-level radioactive waste (HLRW) is isolated hundreds of meters deep in the bedrock. When quantifying the possible leakage of such radioactive compounds in regard to humans and other living organisms, a critical consideration in the assessment models is the groundwater flow through the upper parts of Quaternary deposits (QD; Alexander et al 2003;Kautsky et al 2013;Wörman et al 2019). Another common groundwater contaminant is excess nitrogen in agricultural soils that reaches the stream network through GWF.…”

Section: Introductionmentioning

confidence: 99%

Contrôles géographiques et hydromorphologiques sur les interactions entre l’écoulement hyporhéique et la décharge des eaux souterraines profondes

et al. 2023

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Hyporheic exchange flow (HEF) at the streambed–water interface (SWI) has been shown to impact the pattern and rate of discharging groundwater flow (GWF) and the consequential transport of heat, solutes and contaminants from the subsurface into streams. However, the control of geographic and hydromorphological catchment characteristics on GWF–HEF interactions is still not fully understood. Here, the spatial variability in flow characteristics in discharge zones was investigated and averaged over three spatial scales in five geographically different catchments in Sweden. Specifically, the deep GWF discharge velocity at the SWI was estimated using steady-state numerical models, accounting for the real multiscale topography and heterogeneous geology, while an analytical model, based on power spectral analysis of the streambed topography and statistical assessments of the stream hydraulics, was used to estimate the HEF. The modeling resulted in large variability in deep GWF and HEF velocities, both within and between catchments, and a regression analysis was performed to explain this observed variability by using a set of independent variables representing catchment topography and geology as well as local stream hydromorphology. Moreover, the HEF velocity was approximately two orders of magnitude larger than the deep GWF velocity in most of the investigated stream reaches, indicating significant potential to accelerate the deep GWF velocity and reduce the discharge areas. The greatest impact occurred in catchments with low average slope and in reaches close to the catchment outlet, where the deep GWF discharge velocity was generally low.

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Section: Introductionmentioning

confidence: 99%

Contrôles géographiques et hydromorphologiques sur les interactions entre l’écoulement hyporhéique et la décharge des eaux souterraines profondes

et al. 2023

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“…), and the relation between fractures and fracture sets are also described. Many studies adopted the DFN approach for contaminant transport modelling in fractured rock (Smith and Schwartz, 1984;Alexander et al, 2003;Parker et al, 2012;Lei et. al., 2017).…”

Section: Introductionmentioning

confidence: 99%

Probabilistic analysis of contaminant transport in fractured sedimentary rocks

Manjari

Babu

2021

JGS Special Publication

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Understanding the flow and contaminant transport process in rocks has received increased attention in the past two decades as these geological formations serve as potential sites to contain different types of wastes in geological repositories. In this paper, a discrete fracture network model is developed to understand the process of contaminant transport in a fractured rock mass. This model integrates a stochastic fracture generating algorithm for sedimentary rocks and a two-dimensional numerical model that simulates the flow and transport of a contaminant through the heterogeneous system of fractures. Further, the uncertainty in geological and transport properties of the contaminant are considered as random variables. The probability of concentration exceeding the permissible value at the endpoint is quantified by carrying out reliability analysis using the subset simulation method. The probabilistic framework developed in this study helps assess the behaviour of contaminant migrating through a complex heterogeneous system and provides a basis for gaining a level of confidence in the model results.

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“…Not only can this show that the individual component parts of the complex structure which constitutes most safety assessment models have been checked, but also that the 'mathematical black boxes' (cf. Alexander et al 2003) constitute an acceptable representation of the repository system.…”

Section: Introductionmentioning

confidence: 99%

Natural analogues: studies of geological processes relevant to radioactive waste disposal in deep geological repositories

Alexander¹,

Reijonen²,

McKinley³

2015

Swiss J Geosci

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The geological disposal of radioactive wastes is generally accepted to be the most practicable approach to handling the waste inventory built up from over 70 years accumulation of power production, research-medical-industrial and military wastes. Here, a brief overview of the approach to geological disposal is presented along with some information on repository design and the assessment of repository postclosure safety. One of the significant challenges for repository safety assessment is how to extrapolate the likely long-term (i.e. ten thousand to a million years) behaviour of the repository from the necessarily short term data from analytical laboratories and underground rock laboratories currently available. One approach, common to all fields of the geosciences, but also in such diverse fields as philosophy, biology, linguistics, law etc., is to utilise the analogue argumentation methodology. For the specific case of radioactive waste management, the term 'natural analogue' has taken on a particular meaning associated with providing supporting arguments for a repository safety assessment. This approach is discussed here with a brief overview of how the study of natural (and, in particular, geological) systems can provide supporting information on the likely long-term evolution of a deep geological waste repository. The overall approach is discussed and some relevant examples are presented, including the use of uranium ore bodies to assess waste form stability, the investigation of native metals to define the longevity of waste containers and how natural clays can provide information on the stability of waste tunnel backfill material.

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Chapter 5 Modelling radionuclide transport in the geological environment: a case study from the field of radioactive waste disposal

Cited by 21 publications

References 25 publications

Contrôles géographiques et hydromorphologiques sur les interactions entre l’écoulement hyporhéique et la décharge des eaux souterraines profondes

Contrôles géographiques et hydromorphologiques sur les interactions entre l’écoulement hyporhéique et la décharge des eaux souterraines profondes

Probabilistic analysis of contaminant transport in fractured sedimentary rocks

Natural analogues: studies of geological processes relevant to radioactive waste disposal in deep geological repositories

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