Incorporation of cerium and neodymium in uranyl phases

Kim, Cheol-Woon; Wronkiewicz, David J.; Finch, Robert J.; Buck, Edgar C.

doi:10.1016/j.jnucmat.2006.02.087

Cited by 18 publications

(12 citation statements)

References 16 publications

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“…Final concentrations of Am, Cm and Eu are lower than expected for the formation of the respective pure hydroxides. Kim et al [143] confirmed those results in own coprecipitation experiments where trivalent lanthanides coprecipitated with various U(VI) hydroxide phases and distribution factors of around 10 3 ml/g are found. Based on crystallographic considerations it has also been shown that actinides in their different oxidation states can in principle be accommodated by U(VI) hydroxide and silicate host matrices [149].…”

Section: Radionuclide Retention By Coprecipitation and Sorptionsupporting

confidence: 66%

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

et al. 2012

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UO 2 fuel corrosion / Radionuclide release / Instant release fraction / Hydrogen effect / Coprecipitation / SorptionSummary. Even though chemical processes related to the corrosion of spent nuclear fuel in a deep geological repository are of complex nature, knowledge on underlying mechanisms has very much improved over the last years. As a major result of numerous studies it turns out that alteration of irradiated fuel is significantly inhibited under the strongly reducing conditions induced by container corrosion and consecutive H 2 production. In contrast to earlier results, radiolysis driven fuel corrosion and oxidative dissolution appears to be less relevant for most repository concepts. The protective hydrogen effect on corrosion of irradiated fuel has been evidenced in many experiments. Still, open questions remain related to the exact mechanism and the impact of potentially interfering naturally occurring groundwater trace components. Container corrosion products are known to offer considerable reactive surface area in addition to engineered buffer and backfill material. In combination, waste form, container corrosion products and backfill material represent strong barriers for radionuclide retention and retardation and thus attenuate radionuclide release from the repository near-field.

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Section: Radionuclide Retention By Coprecipitation and Sorptionsupporting

confidence: 66%

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

et al. 2012

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“…Given the small differences in ionic radii (Eu 3+ = 109 pm; Ca 2+ = 114 pm with a six fold coordination number) 15 this is not unexpected, and has been observed in other Ca containing minerals such as calcite. 28 Moreover, from the U : Eu ratio we can suggest that the reaction that occurs (eqn (1)) is the same as the Nd reactivity previously postulated, 19 although the replacement of 2Eu 3+ for 3Ca 2+ may also be possible.…”

Section: Europium(iii) Complexesmentioning

confidence: 59%

An investigation of the interactions of Eu³⁺and Am³⁺with uranyl minerals: implications for the storage of spent nuclear fuel

et al. 2016

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The reaction of a number of uranyl minerals of the (oxy)hydroxide, phosphate and carbonate types with Eu(iii), as a surrogate for Am(iii), have been investigated. A photoluminescence study shows that Eu(iii) can interact with the uranyl minerals Ca[(UO2)6(O)4(OH)6]·8H2O (becquerelite) and A[UO2(CO3)3]·xH2O (A/x = K3Na/1, grimselite; CaNa2/6, andersonite; and Ca2/11, liebigite). For the minerals [(UO2)8(O)2(OH)12]·12H2O (schoepite), K2[(UO2)6(O)4(OH)6]·7H2O (compreignacite), A[(UO2)2(PO4)2]·8H2O (A = Ca, meta-autunite; Cu, meta-torbernite) and Cu[(UO2)2(SiO3OH)2]·6H2O (cuprosklodowskite) no Eu(iii) emission was observed, indicating no incorporation into, or sorption onto the structure. In the examples with Eu(3+) incorporation, sensitized emission is seen and the lifetimes, hydration numbers and quantum yields have been determined. Time Resolved Laser Induced Fluroescence Spectroscpoy (TRLFS) at 10 K have also been measured and the resolution enhancements at these temperatures allow further information to be derived on the sites of Eu(iii) incorporation. Infrared and Raman spectra are recorded, and SEM analysis show significant morphology changes and the substitution of particularly Ca(2+) by Eu(3+) ions. Therefore, Eu(3+) can substitute Ca(2+) in the interlayers of becquerelite and liebigite and in the structure of andersonite, whilst in grimselite only sodium is exchanged. These results have guided an investigation into the reactions with (241)Am on a tracer scale and results from gamma-spectrometry show that becquerelite, andersonite, grimselite, liebigite and compreignacite can include americium in the structure. Shifts in the U[double bond, length as m-dash]O and C-O Raman active bands are similar to that observed in the Eu(iii) analogues and Am(iii) photoluminescence measurements are also reported on these phases; the Am(3+) ion quenches the emission from the uranyl ion.

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“…Because lanthanide ions (Ln 3+ ) are often found in aqueous environments in nature and also as fission products in spent nuclear fuels, successful attempts to fabricate UOH phases incorporating Ln 3+ ions would assist us in understanding other uranyl minerals yet to be discovered and recognizing the behavior of potential uranyl phase evolution within spent nuclear fuels under geological repository conditions. Research on the inclusion of Ln 3+ ions in the interlayer in UOH phases is rather rare, with the first attempt to incorporate Ce 4+ /Nd 3+ as surrogates for Pu 4+ /Am 3+ in ianthinite and becquerelite by coprecipitation and ion-exchange methods in an investigation to explore the possibility for UOH phases to uptake Pu 4+ or Am 3+ . Efforts to dope Ln 3+ ions in UOH phases directly were also made under hydrothermal conditions at 200 °C .…”

Section: Introductionmentioning

confidence: 99%

Syntheses, Crystal Structures, and Spectroscopic Studies of Uranyl Oxide Hydrate Phases with La(III)/Nd(III) Ions

et al. 2019

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We have synthesized two uranyl oxide hydrate (UOH) phases incorporating La(III) or Nd(III) ions under hydrothermal conditions. Investigations with scanning electron microscopy and transmission electron microscopy (TEM) revealed thin-plate morphologies with a U-to-Ln atomic ratio of 2:1 (Ln = La or Nd), while single-crystal X-ray diffraction and TEM electron diffraction studies confirmed that both UOH phases crystallized in the trigonal P31m space group with uranyl oxide layered structures incorporating La(III)/Nd(III) ions as interlayer species. Vibrational spectroscopic studies revealed typical vibrational modes for U ions, with the derived UO bond lengths being comparable to the values reported on other UOH phases. Bond-valence-sum calculations suggest hexavalent uranium in the uranyl form, which was confirmed by the results of diffuse-reflectance and X-ray absorption near-edge structure spectroscopies. This work reports the first single-crystal structural investigation of UOH phases with Ln ions, which has significant implications in the weathering products of uraninite mineral in nature as well as the alteration products of spent nuclear fuels during interim storage and safe disposal over geological timespans.

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Incorporation of cerium and neodymium in uranyl phases

Cited by 18 publications

References 16 publications

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

An investigation of the interactions of Eu³⁺and Am³⁺with uranyl minerals: implications for the storage of spent nuclear fuel

Syntheses, Crystal Structures, and Spectroscopic Studies of Uranyl Oxide Hydrate Phases with La(III)/Nd(III) Ions

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Incorporation of cerium and neodymium in uranyl phases

Cited by 18 publications

References 16 publications

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

Radionuclide behaviour in the near-field of a geological repository for spent nuclear fuel

An investigation of the interactions of Eu3+and Am3+with uranyl minerals: implications for the storage of spent nuclear fuel

Syntheses, Crystal Structures, and Spectroscopic Studies of Uranyl Oxide Hydrate Phases with La(III)/Nd(III) Ions

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An investigation of the interactions of Eu³⁺and Am³⁺with uranyl minerals: implications for the storage of spent nuclear fuel