Characterizing the degradation of [(UO2F2)(H2O)]7 4H2O under humid conditions

JOURNAL OF NUCLEAR MATERIALS

卷:529

Article

Kirkegaard, Marie C.^1,2  Ambrogio, Michael W.¹  Miskowiec, Andrew¹  Shields, Ashley E.¹  Niedziela, J. L.¹  Spano, Tyler L.¹  Anderson, Brian B.^1,2 

[1] Oak Ridge Natl Lab, Nucl Nonproliferat Div, Oak Ridge, TN 37831 USA

[2] Univ Tennessee, Bredesen Ctr Interdisciplinary Res & Grad Educ, Knoxville, TN 37996 USA

关键词: Uranyl fluoride;    Uranyl hydroxide;    Uranyl peroxide;    Uranium;    Raman spectroscopy;    X-ray diffraction;    Relative humidity;    Degradation;   

DOI  :  10.1016/j.jnucmat.2019.151889

来源: Elsevier

【 摘 要 】

Under humid conditions, uranyl fluoride ([(UO2F2)(H2O)](7)center dot 4H(2)O) undergoes a loss of fluorine to form a uranyl hydroxide species, which can be further hydrated to form a uranyl peroxide species. X-ray diffraction data of the uranyl peroxide product is presented for the first time. In addition, the temperature and humidity conditions under which these reactions occur have been clarified by a 220-day experiment using microRaman spectroscopy to track chemical changes in individual particles of uranyl fluoride. At 25 and 35 degrees C, uranyl fluoride is found to be stable at 32% relative humidity but not stable at and above 59% relative humidity. We show that water vapor pressure is the driving factor in formation of both the hydroxide and peroxide products. The kinetics of the transformation from uranyl fluoride into uranyl hydroxide is consistent with a denucleation reaction following the absorption of water molecules. (C) 2019 The Authors. Published by Elsevier B.V.

【 授权许可】

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