A review of uranium corrosion by hydrogen and the formation of uranium hydride

Banos, A.; Harker, N. J.; Scott, Thomas Bligh

doi:10.1016/j.corsci.2018.03.002

Cited by 79 publications

(35 citation statements)

References 122 publications

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“…Teknik hydride-dehydride digunakan untuk bahan yang ulet untuk dibuat serbuk dengan cara dimilling/dihancurkan. Yang perlu diperhatian dalam proses hydridedehydride adalah pembentukan UH3 pada proses hydriding-dehydriding yang dapat menghasilkan produk korosi yang bersifat piroforik sehingga menjadi salah satu masalah dalam hal keselamatan operasionalnya [5].…”

Section: Pendahuluanunclassified

ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI

Masrukan

Mustika²,

Perdana³

et al. 2020

urania

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ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI. Penelitian mengenai komposisi unsur, densitas, makrostruktur, dan fasa paduan U-6Zr-xNb pasca uji korosi telah dilakukan. Analisis komposisi paduan dilakukan sebelum uji korosi yang meliputi uji kadar uranium dengan titrasi potensiometri, uji kadar pengotor dengan Atomic Absorption Spectroscopy (AAS) serta uji kadar Zr dan Nb dengan X-Ray Fluorescence (XRF). Analisis komposisi paduan bertujuan untuk memastikan bahwa bahan bakar U-6Zr-xNb memenuhi syarat kualitas bahan bakar nuklir. Uji densitas dilakukan untuk menjadi salah satu parameter dalam menghitung laju korosi, sedangkan pengamatan makrostruktur dan fasa paduan dilakukan untuk mengetahui kerusakan atau produk korosi serta lapisan/fasa yang terbentuk setelah terjadi korosi. Hasil uji komposisi paduan U-6Zr-xNb dengan XRF maupun titrasi potensiometri menunjukkan bahwa kadar uranium sudah mendekati kadar yang syaratkan, sedangkan untuk uji pengotor dengan AAS menunjukkan adanya kadar pengotor melebihi yang disyaratkan untuk bahan bakar nuklir antara lain Al, Fe dan Si. Berdasarkan hasil tersebut, bahan bakar U-6Zr-xNb masih memenuhi persyaratan. Dilihat dari sifat neutroniknya, unsur Al, Fe dan Si memiliki tampang serapan neutron yang rendah. Hasil uji densitas sampel U-6Zr, U-6Zr-1Nb, U-6Zr-4Nb, dan U-6Zr-7Nb masing-masing sebesar 16,9798 g/mL, 16,6115 g/mL, 15,594 g/mL, dan 15,3564 g/mL. Pengamatan makrostruktur paduan pasca korosi menunjukkan adanya bercak hitam yang merupakan hasil oksidasi U (IV) menjadi U (VI). Paduan U-6Zr-xNb mengalami korosi paling besar pada media air bebas mineral. Kerusakan pada permukaan paduan semakin menurun seiring bertambahnya presentase berat Nb dalam paduan. Hasil karakterisasi paduan pasca korosi menggunakan XRD menunjukkan bahwa sampel U-6Zr dan U-6Zr-1Nb terbentuk fasa α, sedangkan untuk sampel U-6Zr-4Nb dan U-6Zr-7Nb terbentuk fasa γ. Lapisan oksida protektif Nb2O5 yang terbentuk sangat kecil, sehingga tidak terdeteksi oleh XRD.Kata kunci: Paduan UZrNb, komposisi, pengotor, korosi, densitas, makrostruktur, pembentukan fasa.

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Section: Pendahuluanunclassified

ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI

Masrukan

Mustika²,

Perdana³

et al. 2020

urania

View full text Add to dashboard Cite

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“…Here z s (t) is the advecting surface of the expanding solid (such thatż s (t) = v(z = z s (t)) and z s (0) = 0), which is in contact with the atmosphere, leading to a unit concentration for ρ 1 (OH -) by choice of the non-dimensionalisation. The zero condition for ρ 2 (H ) is chosen because outgassing of H 2 is observed experimentally, arising from recombination of H at the surface of the material (H 2 itself is only weakly soluble in UO 2 , see for example Banos et al, 2018). Far from the surface forcing (as z → −∞), we expect to recover an unreacted solid (with only U present).…”

Section: Water Vapourmentioning

confidence: 99%

Asymptotics of Coupled Reaction-Diffusion Fronts With Multiple Static and Diffusing Reactants: Uranium Oxidation in Water Vapor

Natchiar¹,

Hewitt

Monks

et al. 2020

SIAM J. Appl. Math.

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Large-time asymptotic solutions for the reaction-diffusion front between one static and one diffusing reactant are known. These states apply to single step reactions with a mean-field reaction rate proportional to ρ m α n (with m, n ≥ 1), where ρ, α are concentrations of the diffusing and static reactants respectively. Such reaction kinetics commonly arise in, for example, simple corrosion models of a porous solid, subject to a diffusing reactant. Here we address a more complex two-step corrosion reaction for oxidation of uranium in a water-vapour environment. In this case, additional complexity arises through a pair of coupled reaction fronts (one with m = 2, n = 1 and the other with m = 3, n = 1). Furthermore, we allow for material expansion owing to the corrosion process and show that the expected strong dependence of diffusion coefficients on the static reactant distribution is key to explaining experimental observation. In the large-time limit there are four main asymptotic regions, comprising two diffusion layers and two reaction fronts. Asymptotic matching of these regions allows us to construct a large-time solution that gives analytical predictions for the positions of the two propagating fronts, thickness of the diffusion layers and concentration of diffusing species outside of the fronts. This is the first mechanistic model of uranium oxidation in water vapour and (crucially) predicts a thin propagating sub-surface (hydride) layer, as recently observed in atom-probe tomography experiments.

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“…The reaction between U and H are widely accepted to be governed by four stages: the induction period, nucleation and growth period, bulk reaction, and termination period. 1,2 The first two are thought to be the key periods, during which H aggregates and hydride sites nucleate and grow. In the induction period, hydrogen penetrates the surface passivation layer of oxide then gathers at the oxide-metal interface.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of surface uranium hydride formation during corrosion of uranium

Pan

et al. 2019

npj Mater Degrad

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Uranium is widely used in the nuclear industry and it is well known that uranium hydride, UH 3 , forms when uranium is exposed to air. The associated volume change during this transition can cause the surface region to crack, compromising structural integrity. Here, hydriding regions beneath hydride surface craters are studied by secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). Our results indicate that strain transition regions exist, which are induced by hydrogen with a certain thickness between hydride craters and the uranium bulk. The SIMS and XPS results suggest that hydrogen exists covalently with uranium and oxygen in these transition regions. A micro-scale induction period model based on the transition region and previous hydriding models is developed. Within the so-called micro-scale induction period, hydrogen diffuses and accumulates at particular sites before reaching the critical concentration required to form stoichiometric UH 3 in the transition regions.

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A review of uranium corrosion by hydrogen and the formation of uranium hydride

Cited by 79 publications

References 122 publications

ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI

ANALISIS KOMPOSISI UNSUR, DENSITAS, MAKROSTRUKTUR, DAN FASA PADUAN U-6Zr-xNb PASCA UJI KOROSI

Asymptotics of Coupled Reaction-Diffusion Fronts With Multiple Static and Diffusing Reactants: Uranium Oxidation in Water Vapor

Mechanism of surface uranium hydride formation during corrosion of uranium

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