Multimodal X-ray microanalysis of a UFeO₄: evidence for the environmental stability of ternary U(v) oxides from depleted uranium munitions testing

Abstract

<p>An environmentally aged (&gt;25 years) radioactive particle of UFeO₄ recovered from soil contaminated with munitions depleted uranium (DU) was characterised by microbeam multimodal synchrotron X-ray analysis.</p>

Advances and perspectives of actinide chemistry fromex situhigh pressure and high temperature chemical studies

“…Depending on firing velocity, projectile design and target composition pressures and temperatures of over several MPa and above 600 °C can be reached in which oxidation of the DU metal rapidly occurs resulting in binary and ternary oxide formation such as U 3 O 8 , UO 3 , FeUO 4 and Fe 2 UO 6 from primary impact. 31,32 The synthesis of FeUO 4 is known to require elevated pressure. During the detonation of a nuclear weapon, depending on the design, efficiency and assembly of the warhead, extreme pressures and temperatures can be encountered.…”

Application of High-Energy-Resolution X-ray Absorption Spectroscopy at the U L3-Edge to Assess the U(V) Electronic Structure in FeUO4

“…13 The U and iron (Fe) coordination environments in was produced in association with depleted U in the environment. 7 The occurrence of FeUO 4 demonstrates the stability of this phase for more than 25 years in the surface environment. Furthermore, Akiyama et al reported that FeUO 4 could be generated under the Fukushima Dai-ichi Nuclear Power Station's severe accident conditions.…”

“…The U and iron (Fe) coordination environments in FeUO 4 consist of distorted octahedra, [UO 6 ] and [FeO 6 ], with two short axial U–O (2.0465 Å) and Fe–O (1.9913 Å) bonds and four long equatorial U–O (2.1820 and 2.2154 Å) and Fe–O (2.0515 and 2.0901 Å) bonds. Recently, Crean et al found that FeUO 4 was produced in association with depleted U in the environment . The occurrence of FeUO 4 demonstrates the stability of this phase for more than 25 years in the surface environment.…”

“…U­(V), a minor chemical species of U, is less common. However, recent studies have reported that U­(V) is relatively stable in magnetite, − goethite, and depleted U . Its unique characteristics were reported as intermediates during the reduction of U­(VI) to U­(IV). ,,− Therefore, U­(V) compounds have attracted attention in geological, environmental, and actinide chemistry studies.…”

“…Furthermore, Akiyama et al reported that FeUO 4 could be generated under the Fukushima Dai-ichi Nuclear Power Station’s severe accident conditions . Few studies exist on the electronic structure of FeUO 4 . ,− Guo et al reported that all U ions in FeUO 4 would be a 5+ oxidation state by DFT+U calculations (DFT = density functional theory), whereas the U 5+ /U ratio in FeUO 4 is 66.4%, as determined by X-ray photoelectron spectroscopy analysis in the U 4f region . Because of the possibility of surface oxidation, the U 5+ /U ratio does not represent the U valence information for the bulk samples.…”