Site related nucleation and growth of hydrides on uranium surfaces

Arkush, R.; Venkert, A.; Aizenshtein, M.; Zalkind, S.; Moreno, D.; Brill, M.; Mintz, M.H.; Shamir, N.

doi:10.1016/s0925-8388(96)02505-4

Cited by 71 publications

(48 citation statements)

References 7 publications

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“…Ultimately, total conversion of uranium to uranium hydride will occur if there is a sufficient supply of hydrogen. Hydriding behaviour (induction period, rate of hydride growth and morphology of the initial hydride sites) is observed to be influenced by the conditions of growth and features present on the surface of the uranium [3,11,[25][26][27].…”

Section: Discussionmentioning

confidence: 99%

Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

Stitt

Hart

Harker

et al. 2015

Journal of Hazardous Materials

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How do you characterise the contents of a sealed nuclear waste package without breaking it open? This question is important when the contained corrosion products are potentially reactive with air and radioactive. Synchrotron X-rays have been used to perform micro-scale in-situ observation and characterisation of uranium encapsulated in grout; a simulation for a typical intermediate level waste storage packet. X-ray tomography and X-ray powder diffraction generated both qualitative and quantitative data from a grout-encapsulated uranium sample before, and after, deliberately constrained H2 corrosion. Tomographic reconstructions provided a means of assessing the extent, rates and character of the corrosion reactions by comparing the relative densities between the materials and the volume of reaction products. The oxidation of uranium in grout was found to follow the anoxic U + H2O oxidation regime, and the pore network within the grout was observed to influence the growth of uranium hydride sites across the metal surface. Powder diffraction analysis identified the corrosion products as UO2 and UH3, and permitted measurement of corrosion-induced strain. Together, X-ray tomography and diffraction provide means of accurately determining the types and extent of uranium corrosion occurring, thereby offering a future tool for isolating and studying the reactions occurring in real full-scale waste package systems

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Section: Discussionmentioning

confidence: 99%

Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

Stitt

Hart

Harker

et al. 2015

Journal of Hazardous Materials

View full text Add to dashboard Cite

show abstract

“…Prior to the bulk reaction stage, the rate of which is mainly governed by the conditions of the surrounding environment [6][7][8][9][10][11][12][13][14][15], the nucleation and growth stage occurs in a spot-wise manner where hydrides begin to form and grow at certain regions of the metal surface [16]. These regions are assumed to act as low energy points where hydrogen molecules can quickly and easily physi-sorb, chemisorb, dissociate and reach the metal surface to react [16].…”

Section: Introductionmentioning

confidence: 99%

The effect of work-hardening and thermal annealing on the early stages of the uranium-hydrogen corrosion reaction

2018

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A B S T R A C TThe characteristics of hydride formation on metallic U at the early stages were investigated for three differently treated samples. The first sample reacted in its as-received state, the second was thermally annealed and the third sample underwent cold work-hardening prior to reaction with deuterium. From the analysis, the vacuum heat-treated sample was found to be more resilient to hydriding at the nucleation and growth stage, exhibiting a reduced number of nucleation points when compared to the as-cast uranium. The work-hardened sample was observed to be more susceptible to H 2 corrosion, displaying very dissimilar hydriding behaviour when compared to the other.

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“…The uranium-hydrogen reaction usually commences after a period of induction followed by nucleation of individual nuclei specifically located at sites on the metal surface which favour diffusional transport of hydrogen through the overlying uranium oxide layer to the metal (referred to as spot locations) [2,3]. If enough hydrogen is available to sustain the reaction, spot locations will grow laterally (parallel to the metal surface) and eventually coalesce to form a continuous layer across the entire surface of the metal.…”

Section: Introductionmentioning

confidence: 99%

“…inclusions, oxide layer thickness and grain boundaries) [2,3,7,8]. In addition, the rates and thermodynamics of the bulk U-H2 reaction have been thoroughly researched in the literature across a range of temperatures and pressures.…”

Section: Introductionmentioning

confidence: 99%

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The effects of metal surface geometry on the formation of uranium hydride

et al. 2015

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The present work examines the effect of surface geometry on the reaction between hydrogen gas and uranium metal, forming uranium hydride (UH3), a pyrophoric compound of significance to the civil nuclear industry. Hydride formation was initiated on uranium samples that had been patterned with a focused ion beam instrument to form surface arrays of triangular prisms and pillars with differing apex angles. Post reaction analysis indicated preferential hydride formation at the apex of these features. Additionally, once hydride formation had commenced the observed growth rate on the prisms appeared to accelerate in comparison to the rate exhibited on the surrounding surface

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Site related nucleation and growth of hydrides on uranium surfaces

Cited by 71 publications

References 7 publications

Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

The effect of work-hardening and thermal annealing on the early stages of the uranium-hydrogen corrosion reaction

The effects of metal surface geometry on the formation of uranium hydride

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