Hydrogen-oxygen accumulation on polycrystalline uranium surfaces

Swissa, E.; Jacob, I.; Atzmony, U.; Shamir, N.; Mintz, M.H.

doi:10.1016/0039-6028(89)90685-7

Cited by 11 publications

(8 citation statements)

References 25 publications

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“…Numerous spectroscopic studies have been completed in order to investigate the behavior of water and oxygen with UO 2 and pure uranium metal surfaces [10][11][12][13][14][15][16][17][18][19][20][21]. Pure UO 2 and U-based spent nuclear fuel (SNF) have a strong tendency to oxidize in the presence of oxygen and radiolytic oxidants such as H 2 O 2 , OH Á , and HO 2 [22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Corrosion of UO2 and ThO2: A quantum-mechanical investigation

Skomurski

Shuller

Ewing

et al. 2008

Journal of Nuclear Materials

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Section: Introductionmentioning

confidence: 99%

Corrosion of UO2 and ThO2: A quantum-mechanical investigation

Skomurski

Shuller

Ewing

et al. 2008

Journal of Nuclear Materials

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“…In thermal desorption spectroscopy experiments, Balooch et al report that the sticking probability (coverage/exposure) for H2 on polycrystalline a-U is 0.04 at room temperature and a coverage of9xlO experiments, Swissa reports a sticking probability of 0.1 although the model assumptions and concentration of adsorption sites used to derive this value limit its usefulness. 3 In step 2, absorption of H into the bulk is followed by diffusion to trap sites where saturation occurs. Mallet determined the diffusion coefficient (D) ofH in a-U using the degassing rate and a solution of law for cylinders.…”

Section: Introductionmentioning

confidence: 99%

Ab-initio calculations of the hydrogen–uranium system: Surface phenomena, absorption, transport and trapping

Taylor

Lillard

2009

Acta Materialia

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Density functional theory calculations have recently been validated for a-uranium (a-V) metal and, in this work, applied to the initial steps of uranium hydriding: surface phenomena, absorption into the bulk, bulk transport (diffusion) and trapping at defect sites. We investigate the surface chemistry of hydrogen (H) on the (001) surface of a-V, and the influence of high-coordinate geometries on H2 adsorption and dissociation on the metal surface. In the adsorbed state H already has a partially ionic character. Although H adsorbs exothermically to the (001) surface, with respect to the reference state of H 2 , we find that it is endothermic to absorb H into the bulk, with off-center octahedral absorption (Le. a square-pyramidal coordination ofH in the lattice) having the lowest absorption energy of 0.39 eV relative to molecular H2. H absorption in interstitial sites is calculated to cause a local softening of the bulk modulus. The diffusion barrier for H in unstrained a-V is calculated to be 0.6 eV. The energy of H absorption in a site adjacent to the chemical impurities C, S, Si was lowered by an amount proportional to the atomic radii of the impurity atom, and the resulting lattice strain Si > S > C. Thus, impurities may promote hydriding by providing surfaces or pre-strained zones for H uptake.

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“…AES, XPS, etc.) may resolve between processes taking place on the outermost surface layer and those occurring at the subsurface region [20,21]. Due to the grazing angle used, geometrical information may be gained from the effects of shadowing of hydrogen atoms by neighboring larger ones.…”

Section: The Experimental Systemmentioning

confidence: 99%