Uranium minerals and their relevance to long term storage of nuclear fuels

Baker, Robert J.

doi:10.1016/j.ccr.2013.10.004

Cited by 91 publications

(76 citation statements)

References 204 publications

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“…Uranyl carbonates are important phases in the geo-ecology of uranium deposits and nuclear facilities, including radioactive waste disposal sites. Uranyl carbonate minerals readily form during alteration of primary uranium minerals (e.g., pitchblende or uraninite) under the influence of water enriched with CO 2 , which may be derived from the dissolution of carbonate rocks or from the atmosphere [1][2][3][4][5][6]. Uranyl carbonates may play an important role in the transport of uranium in ground waters.…”

Section: Introductionmentioning

confidence: 99%

Structure Refinement and Thermal Stability Studies of the Uranyl Carbonate Mineral Andersonite, Na2Ca[(UO2)(CO3)3]·(5+x)H2O

et al. 2018

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A sample of uranyl carbonate mineral andersonite, Na 2 Ca[(UO 2 )(CO 3 ) 3 ]·5−6H 2 O, originating from the Cane Springs Canyon, San Juan Co., UT, USA was studied using single-crystal and powder X-ray diffraction at various temperatures. Andersonite is trigonal, R−3m, a = 17.8448(4), c = 23.6688(6) Å, V = 6527.3(3) Å 3 , Z = 18, R 1 = 0.018. Low-temperature SCXRD determined the positions of H atoms and disordered H 2 O molecules, arranged within the zeolite-like channels. The results of high-temperature PXRD experiments revealed that the structure of andersonite is stable up to 100 • C; afterwards, it loses crystallinity due to release of H 2 O molecules. Taking into account the well-defined presence of H 2 O molecules forming channels' walls that to the total of five molecules p.f.u., we suggest that the formula of andersonite is Na 2 Ca[(UO 2 )(CO 3 ) 3 ]·(5+x)H 2 O, where x ≤ 1. The thermal behavior of andersonite is essentially anisotropic with the lowest values of the main thermal expansion coefficients in the direction perpendicular to the channels (plane (001)), while the maximal expansion is observed along the c axis-in the direction of channels. The thermal expansion around 80 • C within the (001) plane becomes negative due to the total release of "zeolitic" H 2 O molecules. The information-based structural complexity parameters of andersonite were calculated after the removal of all the disordered atoms, leaving only the predominantly occupied sites, and show that the crystal structure of the mineral should be described as complex, possessing 4.535 bits/atom and 961.477 bits/cell, which is comparative to the values for another very common natural uranyl carbonate, liebigite.

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Section: Introductionmentioning

confidence: 99%

Structure Refinement and Thermal Stability Studies of the Uranyl Carbonate Mineral Andersonite, Na2Ca[(UO2)(CO3)3]·(5+x)H2O

et al. 2018

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“…, Maher et al . , Baker ). Industrially, uranium is solubilised by conversion to uranyl sulfate or uranyl carbonate and leached from its ores for subsequent processing (Edwards and Oliver ).…”

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confidence: 99%

“…Uranium displays some particularly interesting chemistry in the environment. Although most of the world's uranium exists as pitchblende or uraninite (UO 2+x , mixed U(IV) and U(VI) oxides), oxidation, dissolution and reprecipitation produce a variety of secondary uranium minerals, most of which contain the uranyl cation (UO 2 2+ ) (Finch and Ewing 1992, Burns 1999, Morss et al 2007, Maher et al 2012, Baker 2014. Industrially, uranium is solubilised by conversion to uranyl sulfate or uranyl carbonate and leached from its ores for subsequent processing (Edwards and Oliver 2000).…”

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confidence: 99%

Identification of Uranyl Minerals Using Oxygen K‐Edge X‐Ray Absorption Spectroscopy

Ward

Bowden

Resch

et al. 2015

Geostandard Geoanalytic Res

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Although most of the world's uranium exists as pitchblende or uraninite, this mineral can be weathered to a great variety of secondary uranium minerals, most containing the uranyl cation. Anthropogenic uranium compounds can also react in the environment, leading to spatial–chemical alterations that could be useful for nuclear forensics analyses. Soft X‐ray absorption spectroscopy (XAS) has the advantages of being non‐destructive, element‐specific and sensitive to electronic and physical structure. The soft X‐ray probe can also be focused to a spot size on the order of tens of nanometres, providing chemical information with high spatial resolution. However, before XAS can be applied at high spatial resolution, it is necessary to find spectroscopic signatures for a variety of uranium compounds in the soft X‐ray spectral region. To that end, we collected the near edge X‐ray absorption fine structure (NEXAFS) spectra of a variety of common uranyl‐bearing minerals, including uranyl carbonates, oxyhydroxides, phosphates and silicates. We find that uranyl compounds can be distinguished by class (carbonate, oxyhydroxide, phosphate or silicate) based on their oxygen K‐edge absorption spectra. This work establishes a database of reference spectra for future spatially resolved analyses. We proceed to show scanning X‐ray transmission microscopy (STXM) data from a schoepite particle in the presence of an unknown contaminant.

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“…uraninite) are easily dissolved (e.g. Baker, 2014;Boekhout et al, 2015). U +4 is oxidized to U +6 and forms A C C E P T E D M A N U S C R I P T suggest a recycling history.…”

Section: Source Rock Weathering and Recyclingmentioning

confidence: 99%

Provenance and tectonic setting of middle-upper Devonian sandstones in the Qinling Orogen (Shanyang area): New insights from geochemistry, heavy minerals and tourmaline chemistry

et al. 2016

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Uranium minerals and their relevance to long term storage of nuclear fuels

Cited by 91 publications

References 204 publications

Structure Refinement and Thermal Stability Studies of the Uranyl Carbonate Mineral Andersonite, Na2Ca[(UO2)(CO3)3]·(5+x)H2O

Structure Refinement and Thermal Stability Studies of the Uranyl Carbonate Mineral Andersonite, Na2Ca[(UO2)(CO3)3]·(5+x)H2O

Identification of Uranyl Minerals Using Oxygen K‐Edge X‐Ray Absorption Spectroscopy

Provenance and tectonic setting of middle-upper Devonian sandstones in the Qinling Orogen (Shanyang area): New insights from geochemistry, heavy minerals and tourmaline chemistry

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