Geographic Variability in Radon Exhalation at a Rehabilitated Uranium Mine in the Northern Territory, Australia

Bollhöfer, Andreas; Storm, John B.; Martín, Paul; Tims, S.G.

doi:10.1007/s10661-006-4777-z

Cited by 31 publications

(21 citation statements)

References 8 publications

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“…74~77) Radon gas is directly adsorbed on a layer of granular active charcoal distributed over the ground surface, and then charcoal is subjected to -ray spectroscopy detector to estimate the amount of adsorbed radon gas. 6,8,9,35,40,74,78,79) This method has some advantages i.e. radon exhalation rate can be measured easily, the sampling procedures are simple, the charcoal is cheap and can be transported anywhere.…”

Section: Meas Ring Radon Exhalation Rate By Singmentioning

confidence: 99%

Radon Migration Process and Its Influence Factors; Review

Hassan

Hosoda²,

Ishikawa³

et al. 2009

Hoken Butsuri

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Radon (222 Rn) generated within the grains of rocks, soils, building materials and other materials by the radioactive decay of radium ( 226 Ra) can migrate to the atmosphere. This paper reviews the emanation coefficient, diffusion coefficient, and exhalation rate, and the factors that control the rate at which radon can enter atmosphere. The emanation coefficient which is the fraction of radon generated within the grains of materials and escaped to the pore space, varied from 2.1 to 32% for rocks, from 0.14 to 80% for soil, and from 0.10 to 58% in case of building materials. In addition, measurement methods used to evaluate emanation coefficient and its influence factors are also reviewed. The diffusion of radon is a process determined by radon concentration gradient across the radon sources and the surrounding air. The effective diffusion coefficient of some materials is summarized. Moreover, the radon exhalation rate process and the main influencing factors on the variation of exhalation rate data are reviewed. The exhalation rate varied in the range of 0.11 to 80 mBq m -2 s -1 , 2.0 10 -3 to 5.0 10 4 mBq m -2 s -1 and 4.0 10 -3 to 5.0 10 1 mBq m -2 s -1 for rocks, soils and building materials, respectively.

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Section: Meas Ring Radon Exhalation Rate By Singmentioning

confidence: 99%

Radon Migration Process and Its Influence Factors; Review

Hassan

Hosoda²,

Ishikawa³

et al. 2009

Hoken Butsuri

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“…At the former Nabarlek uranium project in the Northern Territory, Australia, rehabilitation works have actually achieved an overall reduction in radon flux compared to premining (Bollhöffer et al 2006). Prior to mining, very high-grade ore ([1% U 3 O 8 ) outcropped at the surfaced, leading to radon fluxes from 3.7 to 44.0 Bq/m 2 /s (Clark et al 1981).…”

Section: Remediation Approachesmentioning

confidence: 99%

“…Prior to mining, very high-grade ore ([1% U 3 O 8 ) outcropped at the surfaced, leading to radon fluxes from 3.7 to 44.0 Bq/m 2 /s (Clark et al 1981). Mining saw the tailings buried up to half the depth in the mined out pit (*100 m deep), with low grade and waste rock filling the remainder of the pit-thus leading to a weaker radon source in the near surface materials and soil covers averaging about 1.0 Bq/m 2 /s over the same region (Bollhöffer et al 2006). Recently, however, a small area (0.44 ha) has shown significant erosion leading to exposure of the underlying radioactive wastes, giving a radon flux of 6.51 Bq/m 2 /s (Bollhöffer et al 2006).…”

Section: Remediation Approachesmentioning

confidence: 99%

“…Mining saw the tailings buried up to half the depth in the mined out pit (*100 m deep), with low grade and waste rock filling the remainder of the pit-thus leading to a weaker radon source in the near surface materials and soil covers averaging about 1.0 Bq/m 2 /s over the same region (Bollhöffer et al 2006). Recently, however, a small area (0.44 ha) has shown significant erosion leading to exposure of the underlying radioactive wastes, giving a radon flux of 6.51 Bq/m 2 /s (Bollhöffer et al 2006). At many projects in Australia, it appears very difficult to achieve a pre-mining radon flux after rehabilitation, especially in the long term (Mudd 2008b).…”

Section: Remediation Approachesmentioning

confidence: 99%

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Radon sources and impacts: a review of mining and non-mining issues

Mudd

2008

Rev Environ Sci Biotechnol

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Radon is a ubiquitous natural carcinogen derived from the three primordial radionuclides of the uranium series ( 238 U and 235 U) and thorium series ( 232 Th). In general, it is present at very low concentrations in the outdoor or indoor environment, but a number of scenarios can give rise to significant radiological exposures. Historically, these scenarios were not recognised, and took many centuries to understand the links between the complex behaviour of radon and progeny decay and health risks such as lung cancer. However, in concert with the rapid evolution in the related sciences of nuclear physics and radiological health in the first half of the twentieth century, a more comprehensive understanding of the links between radon, its progeny and health impacts such as lung cancer has evolved. It is clear from uranium miner studies that acute occupational exposures lead to significant increases in cancer risk, but chronic or sub-chronic exposures, such as indoor residential settings, while suggestive of health risks, still entails various uncertainties. At present, prominent groups such as the BEIR or UNSCEAR committees argue that the 'linear no threshold' (LNT) model is the most appropriate model for radiation exposure management, based on their detailed review and analysis of uranium miner, residential, cellular or molecular studies. The LNT model implies that any additional or excess exposure to radon and progeny increases overall risks such as lung cancer. A variety of engineering approaches are available to address radon exposure problems. Where high radon scenarios are encountered, such as uranium mining, the most cost effective approach is well-engineered ventilation systems. For residential radon problems, various options can be assessed, including building design and passive or active ventilation systems. This paper presents a very broad but thorough review of radon sources, its behaviour (especially the importance of its radioactive decay progeny), common mining and non-mining scenarios which can give rise to significant radon and progeny exposures, followed by a review of associated health impacts, culminating in typical engineering approaches to reduce exposures and rehabilitate wastes.

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“…will need to be taken into account, and work is underway to investigate these (e.g. Bollhöfer et al, 2003Bollhöfer et al, , 2004. Nevertheless, the present work does enable estimates of the contribution to dose rates from γ radiation to be made.…”

Section: γ Dose Rate Estimationmentioning

confidence: 99%

Use of Airborne γ-Ray Spectrometry for Environmental Assessment of the Rehabilitated Nabarlek Uranium Mine, Australia

Martín

Tims

McGill³

et al. 2006

Environ Monit Assess

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This article describes an airborne gamma survey of a 7 x 5 km region around the rehabilitated Nabarlek uranium mine in northern Australia. An unusually tight line spacing (100 m) and low aircraft height (50 m) were used, enabling the survey to distinguish man-made structures such as ponds and accommodation areas, as well as creek lines. Positive correlations between airborne data and ground-based readings enabled an estimation of the average absorbed dose rate arising from terrestrial gamma radiation over large areas of the site to be derived. For the fenced minesite area this estimate was 0.31 micro Gy hr(- 1). The airborne survey data were found to be invaluable in helping to plan further ground-level investigations and showed promise as an assessment tool for rehabilitated minesites.

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Geographic Variability in Radon Exhalation at a Rehabilitated Uranium Mine in the Northern Territory, Australia

Cited by 31 publications

References 8 publications

Radon Migration Process and Its Influence Factors; Review

Radon Migration Process and Its Influence Factors; Review

Radon sources and impacts: a review of mining and non-mining issues

Use of Airborne γ-Ray Spectrometry for Environmental Assessment of the Rehabilitated Nabarlek Uranium Mine, Australia

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