Analytical risk-based model of gaseous and liquid-phase radon transport in landfills with radium sources

Ho, Clifford K.

doi:10.1016/j.envsoft.2008.01.002

Cited by 9 publications

(7 citation statements)

References 16 publications

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“…Indeed, with 1 m wide fracture or moderate water flow rate of 1 L s À1 , water is able to collect radon from the porous medium of the degassed zone, increasing its radon concentration toward the surface ( Figure A1). In addition, standard two-phase radon transport equations in a stratified porous medium were used [Ho, 2008]. Both in diffusive and in advective domains, the standard framework established by Rogers and Nielson [1991a] and Nazaroff [1992] was used.…”

Section: Appendix A: Equations Of the Water Degassing Model (M1)mentioning

confidence: 99%

“…For radon, three phases were considered: gas phase, water phase (radon dissolved in water), and adsorbed phase (radon adsorbed onto mineral surfaces). In addition, standard two-phase radon transport equations in a stratified porous medium were used [Ho, 2008]. At radioactive equilibrium, radon concentration in air C 0 a (expressed in Bq m À3 ) is defined by:…”

Section: Appendix A: Equations Of the Water Degassing Model (M1)mentioning

confidence: 99%

“…To make quantitative predictions, equation (B6) was solved in stationary regime [Ho, 2008]. For a stratified medium, initial and boundary conditions were a fixed radon concentration at the surface C e and continuity of radon concentration and flux at interfaces.…”

Section: Appendix A: Equations Of the Water Degassing Model (M1)mentioning

confidence: 99%

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The Syabru‐Bensi hydrothermal system in central Nepal: 2. Modeling and significance of the radon signature

Girault

Perrier

2014

JGR Solid Earth

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The Syabru-Bensi hydrothermal system (SBHS), located in the Nepal Himalayas, is characterized by numerous hot (>30°C) springs and the release of dry, cold (<35°C) CO 2 associated with radon-222, detailed in the companion paper. In the SBHS, CO 2 and radon fluxes on the ground vary over 5-6 orders of magnitude, reaching exceptional mean values of 100 kg m À2 d À1 and 12 Bq m À2 s À1 , respectively. This paper extends the companion paper by developing three quantitative models for the radon signature of CO 2 based on measurements of radon and radium concentrations in the spring waters and effective radium concentration of rocks and soils. The first model considers near-surface radon and CO 2 degassing from water, considered unlikely unless there exist currently unidentified large discharges of hydrothermal water. The second model considers CO 2 , arising from deeper hydrothermal sources, incorporating radon from shallow radium sources as it percolates upward toward the surface, considered more likely as a percolation depth of 100 m is sufficient to account for the observed radon discharge. The third model considers the observed peak radon concentrations in the gas zones and assumes that gaseous CO 2 can be transported from kilometer-scale depths through a fault network connected to the zones. This latter model affords the possibility that variations of physical parameters at depths associated with earthquake nucleation might be detectable at the surface. Gas-dominated transport might operate in other locations in Himalayas and elsewhere and may be an important aspect of the coupled mechanisms associated with seismically active orogens.

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Section: Appendix A: Equations Of the Water Degassing Model (M1)mentioning

confidence: 99%

Section: Appendix A: Equations Of the Water Degassing Model (M1)mentioning

confidence: 99%

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The Syabru‐Bensi hydrothermal system in central Nepal: 2. Modeling and significance of the radon signature

Girault

Perrier

2014

JGR Solid Earth

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“…However, Ho (2008) showed the importance of high rainfall events in predicting radon exhalation from Uranium Mill Tailings (UMT) landfill soils. This approximation can be legitimate for some conditions, such as in the absence of rainfall or irrigation events at the soil surface.…”

Section: First Approximationmentioning

confidence: 99%

On the Air-filled Effective Porosity Parameter of Rogers and Nielson’s (1991) Bulk Radon Diffusion Coefficient in Unsaturated Soils

Saâdi¹

2014

Health Physics

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The radon exhalation rate at the earth's surface from soil or rock with radium as its source is the main mechanism behind the radon activity concentrations observed in both indoor and outdoor environments. During the last two decades, many subsurface radon transport models have used Rogers and Nielson's formula for modeling the unsaturated soil bulk radon diffusion coefficient. This formula uses an "air-filled effective porosity" to account for radon adsorption and radon dissolution in the groundwater. This formula is reviewed here, and its hypotheses are examined for accuracy in dealing with subsurface radon transport problems. The author shows its limitations by comparing one dimensional steady-state analytical solutions of the two-phase (air/water) transport equation (Fick's law) with Rogers and Nielson's formula. For radon diffusion-dominated transport, the calculated Rogers and Nielson's radon exhalation rate is shown to be unrealistic as it is independent of the values of the radon adsorption and groundwater dissolution coefficients. For convective and diffusive transport, radon exhalation rates calculated using Fick's law and this formula agree only for high values of gas-phase velocity and groundwater saturation. However, these conditions are not usually met in most shallow subsurface environments where radon migration takes place under low gas phase velocities and low water saturation.

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“…The problem of modeling the contamination of a superficial aquifer due to contaminant release is a classical groundwater quality problem (Bear 1979;Bear and Cheng 2010) and several analytical and/or numerical approaches have been proposed in the literature for addressing problems which bear some similarities with ours (Nair and Krishnamoorthy 1999;Ho 2008;Troldborg 2010;Simunek et al 2007;Pacific Northwest National Laboratory 2004). Many of these resolution methods, indeed, allow very detailed analyses, but the computational effort that they require is often so large that the uncertainty and sensitivity analyses needed within risk assessment become almost impractical (Pacific Northwest National Laboratory 2004), and it significantly increases as the amount and the complexity of the modeled physical processes increase.…”

Section: Introductionmentioning

confidence: 98%

Modeling the release and transport of 90Sr radionuclides from a superficial nuclear storage facility

Cadini

Tosoni

Zio

2015

Stoch Environ Res Risk Assess

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This work illustrates an integrated model for (i) predicting the evolution of radionuclide concentrations due to releases from a spent fuel storage pool and (ii) providing a preliminary assessment of the radiological risk for the local population. The model integrates (i) a particle tracking algorithm for radionuclide transport based on the Kolmogorov-Dmitriev theory of branching stochastic processes and (ii) a semi-empirical model for representing the effects of seasonal variations in the water table level on the radionuclide concentrations. A real case study is considered concerning the release of 90 Sr from the spent fuel storage pool at the EUREX site in Italy. The integrated model is calibrated by a genetic algorithm optimization based on observation data of water table levels and 90 Sr concentrations available from the local monitoring network. The proposed model offers a satisfactory trade-off between a detailed physical and geometrical description of the transport processes and computational efficiency.

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Analytical risk-based model of gaseous and liquid-phase radon transport in landfills with radium sources

Cited by 9 publications

References 16 publications

The Syabru‐Bensi hydrothermal system in central Nepal: 2. Modeling and significance of the radon signature

The Syabru‐Bensi hydrothermal system in central Nepal: 2. Modeling and significance of the radon signature

On the Air-filled Effective Porosity Parameter of Rogers and Nielson’s (1991) Bulk Radon Diffusion Coefficient in Unsaturated Soils

Modeling the release and transport of 90Sr radionuclides from a superficial nuclear storage facility

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