Radioactive and other environmental contamination from uranium mining and milling

Falck, W. Eberhard

doi:10.1016/b978-1-78242-231-0.00001-6

Cited by 6 publications

(6 citation statements)

References 12 publications

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“…Uranium (U) has been released into the environment through mining activities, weapons use, and via authorized discharges and accidents at nuclear sites. − It is typically the largest radionuclide by mass in many higher activity radioactive wastes that will be managed via geological disposal, where U exists in a range of chemical forms . Uranium is radiotoxic, chemotoxic, long-lived ( 235 U half-life = 703.8 × 10 6 years, 238 U 4.468 × 10 9 years), and persists in the subsurface; thus, it poses a significant environmental and human health risk. , As such, understanding U behavior in the geosphere is essential.…”

Section: Introductionmentioning

confidence: 99%

“…Metaschoepite (a U(VI) oxide) is a primary product of depleted uranium munition corrosion in former war zones (e.g., Gulf and Balkan Wars) and at military test sites. − It also forms upon oxidation of UO 2 in the environment, , and UO 2 can be formed at U contaminated sites during U(VI) (aq) biostimulation, or be dispersed in the environment during mining activities or through nuclear accidents. ,,, Large volumes of uranium wastes, which include significant amounts of metaschoepite, may also be managed by either shallow or deep disposal in the UK. , Despite this, the environmental behavior of metaschoepite, and its impact on U transport in complex, dynamic environmental systems is poorly constrained.…”

Section: Introductionmentioning

confidence: 99%

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Metaschoepite Dissolution in Sediment Column Systems—Implications for Uranium Speciation and Transport

Bower

Morris

Livens³

et al. 2019

Environ. Sci. Technol.

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Metaschoepite is commonly found in U-contaminated environments and metaschoepite-bearing wastes may be managed via shallow or deep disposal. Understanding metaschoepite dissolution and tracking the fate of any liberated U is thus important. Here, discrete horizons of metaschoepite (UO 3 • nH 2 O) particles were emplaced in flowing sediment/groundwater columns representative of the UK Sellafield Ltd. site. The column systems either remained oxic or became anoxic due to electron donor additions, and the columns were sacrificed after 6-and 12-months for analysis. Solution chemistry, extractions, and bulk and micro/nano-focus X-ray spectroscopies were used to track changes in U distribution and behavior. In the oxic columns, U migration was extensive, with UO 2 2+ identified in effluents after 6-months of reaction using fluorescence spectroscopy. Unusually, in the electron-donor amended columns, during microbially mediated sulfate reduction, significant amounts of UO 2 -like colloids (>60% of the added U) were found in the effluents using TEM. XAS analysis of the U remaining associated with the reduced sediments confirmed the presence of trace U(VI), noncrystalline U(IV), and biogenic UO 2 , with UO 2 becoming more dominant with time. This study highlights the potential for U(IV) colloid production from U(VI) solids under reducing conditions and the complexity of U biogeochemistry in dynamic systems.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Metaschoepite Dissolution in Sediment Column Systems—Implications for Uranium Speciation and Transport

Bower

Morris

Livens³

et al. 2019

Environ. Sci. Technol.

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“…Uranium (U) has been released to the environment through civil nuclear and defense related activities worldwide. Sources of contamination include U mining, waste effluent discharges, weapons testing/fallout, and nuclear accidents (Salbu et al, 2003;Lind et al, 2007;McDonald, 2011;Falck, 2015;Imoto et al, 2017;Ochiai et al, 2018). Uranium is a redox-active, radio-and chemo-toxic element, and it is potentially mobile in the environment.…”

Section: Introductionmentioning

confidence: 99%

Vadose-zone alteration of metaschoepite and ceramic UO2 in Savannah River Site field lysimeters

Fallon

Bower

Powell

et al. 2023

Science of The Total Environment

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“…Uranium (U) is typically the most abundant radionuclide by mass in both the nuclear fuel cycle and many radioactive waste inventories. , It is also a contaminant associated with uranium mining and where accidental release of radionuclides to the environment has occurred. , Understanding the speciation and mobility of uranium in interim storage, waste processing, and contaminated land is important in underpinning safe decommissioning and management of operations at nuclear facilities. The mobility and lability of uranium in aqueous systems is controlled by its chemical speciation.…”

Section: Introductionmentioning

confidence: 99%

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

et al. 2022

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In the United Kingdom, decommissioning of legacy spent fuel storage facilities involves the retrieval of radioactive sludges that have formed as a result of corrosion of Magnox nuclear fuel. Retrieval of sludges may re-suspend a colloidal fraction of the sludge, thereby potentially enhancing the mobility of radionuclides including uranium. The colloidal properties of the layered double hydroxide (LDH) phase hydrotalcite, a key product of Magnox fuel corrosion, and its interactions with U(VI) are of interest. This is because colloidal hydrotalcite is a potential transport vector for U(VI) under the neutral-to-alkaline conditions characteristic of the legacy storage facilities and other nuclear decommissioning scenarios. Here, a multi-technique approach was used to investigate the colloidal stability of hydrotalcite and the U(VI) sorption mechanism(s) across pH 7–11.5 and with variable U(VI) surface loadings (0.01–1 wt %). Overall, hydrotalcite was found to form stable colloidal suspensions between pH 7 and 11.5, with some evidence for Mg 2+ leaching from hydrotalcite colloids at pH ≤ 9. For systems with U present, >98% of U(VI) was removed from the solution in the presence of hydrotalcite, regardless of pH and U loading, although the sorption mode was affected by both pH and U concentrations. Under alkaline conditions, U(VI) surface precipitates formed on the colloidal hydrotalcite nanoparticle surface. Under more circumneutral conditions, Mg 2+ leaching from hydrotalcite and more facile exchange of interlayer carbonate with the surrounding solution led to the formation of uranyl carbonate species (e.g., Mg(UO 2 (CO 3 ) 3 ) 2– (aq) ). Both X-ray absorption spectroscopy (XAS) and luminescence analysis confirmed that these negatively charged species sorbed as both outer- and inner-sphere tertiary complexes on the hydrotalcite surface. These results demonstrate that hydrotalcite can form pseudo-colloids with U(VI) under a wide range of pH conditions and have clear implications for understanding the uranium behavior in environments where hydrotalcite and other LDHs may be present.

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Radioactive and other environmental contamination from uranium mining and milling

Cited by 6 publications

References 12 publications

Metaschoepite Dissolution in Sediment Column Systems—Implications for Uranium Speciation and Transport

Metaschoepite Dissolution in Sediment Column Systems—Implications for Uranium Speciation and Transport

Vadose-zone alteration of metaschoepite and ceramic UO2 in Savannah River Site field lysimeters

Hydrotalcite Colloidal Stability and Interactions with Uranium(VI) at Neutral to Alkaline pH

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