Effect of iron on hydrogen absorption properties of zirconium alloys

Kakiuchi, Kazuo; Itagaki, Noboru; Furuya, Takemi; Miyazaki, Akihiro; Ishii, Yoshinori; Suzuki, Shunichi; Terai, Takayuki; Yamawaki, Michio

doi:10.1016/j.jpcs.2004.06.061

“…This, in turn, would mean that more electrons were consumed at the surface, making the electronic potential there higher, allowing electrons formed from the oxidation of the metal to flow out more easily. This decreases the overall electrical potential gradient across the oxide, which should decrease the ingress of hydrogen into the metal [32,33]. An increased oxygen vacancy concentration could also affect the corrosion rate via its stabilizing effect on tetragonal ZrO 2 [34] as some studies [35][36][37] suggest that the tetragonal-to-monoclinic phase change induces the transition from low to high corrosion rates.…”

Section: Introductionmentioning

confidence: 99%

Modelling and experimental analysis of the effect of solute iron in thermally grown Zircaloy-4 oxides

Than

¹

,

Wenman

²

,

Bell

³

et al. 2018

Journal of Nuclear Materials

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Simulations based on density functional theory (DFT) were used to investigate the behaviour of substitutional iron in both tetragonal and monoclinic ZrO 2. Brouwer diagrams of predicted defect concentrations, as a function of oxygen partial pressure, suggest that iron behaves as a p-type dopant in monoclinic ZrO 2 while it binds strongly to oxygen vacancies in tetragonal ZrO 2. Analysis of defect relaxation volumes suggest that these results should hold true in thermally grown oxides on zirconium, which is under compressive stresses. X-ray absorption near edge structure (XANES) measurements, performed to determine the oxidation state of iron in Zircaloy-4 oxide samples, revealed that 3+ is the favourable oxidation state but with between a third and half of the iron, still in the metallic Fe 0 state. The DFT calculations on bulk zirconia agree with the preferred oxidation state of iron if it is a substitutional species but do not predict the presence of metallic iron in the oxide. The implications of these results with respect to the corrosion and hydrogen pickup of zirconium cladding are discussed.

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“…In order to clarify this mechanism, the surface potential of the oxide film for both Zry-2 and HiFi alloy was investigated using an electrochemical technique. 3,4) The oxide surface potential was measured by PEC (photoelectrochemical) 4) measurement. A schematic view of the PEC measurement system and the photocurrent response for pre-oxidized sample (oxide thickness 0.2 mm) are shown in Figs.…”

Section: Tests On Hydrogen Absorption Mechanismmentioning

confidence: 99%

Irradiated Behavior at High Burnup for HiFi Alloy

Kakiuchi¹,

Ohira²,

Itagaki³

et al. 2006

J. Nucl. Sci. Technol.

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Irradiation tests of a BWR advanced Zr alloy (HiFi alloy) and Zircaloy-2 (Zry-2) were carried out in a Japanese commercial reactor and the irradiation performances of the materials were investigated. HiFi alloy and Zry-2 showed excellent resistance to corrosion up to 70 GWd/t, and furthermore, HiFi kept lower hydrogen pickup compared with Zry-2. TEM observation showed that the Fe/(Fe+Cr) ratio of Zr(Fe,Cr) 2 type second phase particles (SPPs) for HiFi alloy and Zry-2 tended to decrease as fast neutron fluence increased and to saturate at high fluence. Zr-Fe-Cr SPPs did not completely disappear even for 6 cycles for the irradiated HiFi alloy and Zry-2. In order to clarify the mechanism of hydrogen absorption, an electrochemical technique was used for the oxide film of both materials as part of the out-ofpile test. The relation between the oxide surface potential and the hydrogen pickup fraction was estimated suggesting that the potential difference over the oxide film suppressed hydrogen (proton) diffusion in the oxide film.

show abstract

“…In order to clarify this mechanism, the surface potential of the oxide film for both Zry-2 and HiFi alloy was investigated using an electrochemical technique. 3,4) The oxide surface potential was measured by PEC (photoelectrochemical) 4) measurement. A schematic view of the PEC measurement system and the photocurrent response for pre-oxidized sample (oxide thickness 0.2 mm) are shown in Figs.…”

Section: Tests On Hydrogen Absorption Mechanismmentioning

confidence: 99%

Irradiated Behavior at High Burnup for HiFi Alloy

Kakiuchi¹,

Ohira²,

Itagaki³

et al. 2006

Journal of Nuclear Science and Technology

Self Cite

View full text Add to dashboard Cite

Irradiation tests of a BWR advanced Zr alloy (HiFi alloy) and Zircaloy-2 (Zry-2) were carried out in a Japanese commercial reactor and the irradiation performances of the materials were investigated. HiFi alloy and Zry-2 showed excellent resistance to corrosion up to 70 GWd/t, and furthermore, HiFi kept lower hydrogen pickup compared with Zry-2. TEM observation showed that the Fe/(Fe+Cr) ratio of Zr(Fe,Cr) 2 type second phase particles (SPPs) for HiFi alloy and Zry-2 tended to decrease as fast neutron fluence increased and to saturate at high fluence. Zr-Fe-Cr SPPs did not completely disappear even for 6 cycles for the irradiated HiFi alloy and Zry-2. In order to clarify the mechanism of hydrogen absorption, an electrochemical technique was used for the oxide film of both materials as part of the out-ofpile test. The relation between the oxide surface potential and the hydrogen pickup fraction was estimated suggesting that the potential difference over the oxide film suppressed hydrogen (proton) diffusion in the oxide film.

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Effect of iron on hydrogen absorption properties of zirconium alloys

Cited by 10 publications

References 5 publications

Modelling and experimental analysis of the effect of solute iron in thermally grown Zircaloy-4 oxides

Modelling and experimental analysis of the effect of solute iron in thermally grown Zircaloy-4 oxides

Irradiated Behavior at High Burnup for HiFi Alloy

Irradiated Behavior at High Burnup for HiFi Alloy

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