The Poços de Caldas project: an introduction and summary of its implications for radioactive waste disposal

Chapman, Neil; McKinley, Ian G.; Franca, Eduardo Penna; Shea, Michael; Smellie, J.A.T.

doi:10.1016/0375-6742(92)90120-w

Cited by 33 publications

(10 citation statements)

References 2 publications

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“…Another example of channeling is seen Figure 2, in the Pocos de Caldas uranium mine in Brazil [ Chapman et al , 1992]. Water containing oxygen has for millions of years infiltrated the fractured rock.…”

Section: Introductionmentioning

confidence: 99%

Channeling with diffusion into stagnant water and into a matrix in series

Neretnieks

2006

Water Resources Research

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[1] Numerous field observations show that most water flow in fractured rocks takes place in only a small part of the fractures. We call these channels. Solutes in the flowing water can diffuse in and out of stagnant water in the porous rock matrix that the flowing water contacts via the so-called flow wetted surface (FWS). In addition, the solutes can diffuse into stagnant water in the fractures themselves and from this water further into the rock matrix. For narrow channels with small FWS the transport via the stagnant water in the fracture can considerably add to the exchange of solutes between flowing water and matrix water. For sorbing solutes that interact with the micropore surfaces in the matrix the effect can be very strong. Some models that account for these processes are developed and solved using Laplace transforms. Some examples are presented that show the effects of first diffusion into stagnant waters in fractures with subsequent diffusion into the rock matrix. Effects of slit-like and tube-like channels are considered as well as the presence of intersecting fractures. The solutions are especially useful to model solute transport in complex three-dimensional channels networks where wide and narrow or even tube-like channels with widely varying flow rates combine into a multitude of different paths.

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Section: Introductionmentioning

confidence: 99%

Channeling with diffusion into stagnant water and into a matrix in series

Neretnieks

2006

Water Resources Research

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“…1). The Poços de Caldas plateau is considered the largest alkaline complex in Brazil (Holmes et al, 1992) with one of the largest uranium occurrences in the world (Chapman et al, 1992). In addition to uranium, there are also important bauxite deposits and sulfuric thermal springs (Fernandes and Franklin, 2001).…”

Section: Settingmentioning

confidence: 99%

Intelligent estimation of spatially distributed soil physical properties

Iwashita

Friedel

Ribeiro³

et al. 2012

Geoderma

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“…the Buffer Mass Test area of Pusch et al (1985) and the site characterization and validation drift of Harding and Black (1992)-into the Kymmen (Moreno and Neretnieks 1989) and Bolmen tunnels in Sweden (Neretnieks 2006), and into tunnels in the Aar and Gotthard massifs of Switzerland (Masset and Loew 2010). At Pocos de Caldas uranium mine in Brazil, patches of oxidized pyrite associated with groundwater flow are observed together with channels of 100 m or more in length (Chapman et al 1992). …”

Section: Sparsenessmentioning

confidence: 99%

Groundwater flow into underground openings in fractured crystalline rocks: an interpretation based on long channels

Black¹,

Woodman

Barker

2016

Hydrogeol J

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Rethinking an old tracer experiment in fractured crystalline rock suggests a concept of groundwater flow in sparse networks of long channels that is supported by results from an innovative lattice network model. The model, HyperConv, can vary the mean length of 'strings' of connected bonds, and the gaps between them, using two independent probability functions. It is found that networks of long channels are able to percolate at lower values of (bond) density than networks of short channels. A general relationship between mean channel length, mean gap length and probability of percolation has been developed which incorporates the well-established result for 'classical' lattice network models as a special case. Using parameters appropriate to a 4-m diameter drift located 360 m below surface at Stripa Mine Underground Research Laboratory in Sweden, HyperConv is able to reproduce values of apparent positive skin, as observed in the so-called Macropermeability Experiment, but only when mean channel length exceeds 10 m. This implies that such channel systems must cross many fracture intersections without bifurcating. A general relationship in terms of flow dimension is suggested. Some initial investigations using HyperConv show that the commonly observed feature, 'compartmentalization', only occurs when channel density is just above the percolation threshold. Such compartments have been observed at Kamaishi Experimental Mine (Japan) implying a sparse flow network. It is suggested that compartments and skin are observable in the field, indicate sparse channel systems, and could form part of site characterization for deep nuclear waste repositories.

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The Poços de Caldas project: an introduction and summary of its implications for radioactive waste disposal

Cited by 33 publications

References 2 publications

Channeling with diffusion into stagnant water and into a matrix in series

Channeling with diffusion into stagnant water and into a matrix in series

Intelligent estimation of spatially distributed soil physical properties

Groundwater flow into underground openings in fractured crystalline rocks: an interpretation based on long channels

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