Delayed hydride cracking of Zr-2.5%Nb pressure tube material due to partially constrained precipitates

Murty, Theta; Singh, R.N.; Ståhle, Per

doi:10.1016/j.jnucmat.2018.10.040

Cited by 25 publications

(2 citation statements)

References 49 publications

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“…Some of this hydrogen enters the metal to form hydrides which adversely change properties like the fracture toughness. Delayed hydride cracking can occur if sharp flaws, cuts, and nicks suffered during operation coincide with regions under tensile stresses [4][5][6]. Optical micrographs taken in these pressure tubes show that the size of hydrides close to the metal-oxide interface can be smaller than in the bulk [7,8].…”

Section: Introductionmentioning

confidence: 99%

Denuded zones in zirconium pressure vessels: oxygen’s role examined via multi-scale diffusion model

Liyanage

Miller

Rajapakse

2020

Modelling Simul. Mater. Sci. Eng.

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Zirconium alloys are extensively used as cladding material in nuclear reactors. They are vulnerable to hydrogen degradation under the harsh service conditions of the reactors. Optical micrographs taken in some pressure tubes shows the presence of hydride denuded zones closer to the surface, where the hydrides formed in this region are smaller in size compared to the bulk. We investigated the effect of oxygen on diffusivity of hydrogen in α Zr, to check the hypothesis that oxygen slows the diffusion of hydrogen and thereby encourages the occurrence of hydride denuded zones. We used a multi-scale model to simulate H diffusion in Zr with different O concentrations to identify the effect that O has on H diffusivity. From the study we found that oxygen indeed decreases the diffusivity of hydrogen in α Zr for moderate oxygen concentrations. We investigated the diffusion processes of individual H atoms, which showed that the reduction in diffusivity is caused by a decrease in the hopping rates and the formation of hydrogen traps by the combination of several interstitial sites. Though the diffusivity of H seems to be reduced by O, looking at the O concentration profiles found in Zircaloy pressure tubes, we see that the slowing down is insufficient to cause a significant enough change to the size of hydride precipitates. This causes us to reject the hypothesis as the main reason for the formation of denuded zones in Zircaloy pressure tubes.

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Section: Introductionmentioning

confidence: 99%

Denuded zones in zirconium pressure vessels: oxygen’s role examined via multi-scale diffusion model

Liyanage

Miller

Rajapakse

2020

Modelling Simul. Mater. Sci. Eng.

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“…Some of this hydrogen enters the metal which adversely changes its properties like the fracture toughness. Delayed hydride cracking can also occur if sharp flaws, cuts, and nicks suffered during operation coincide with regions under tensile stresses [4][5][6]. Hence, the hydride content in these pressure tubes are continuously monitored through scrape samples taken from their surfaces.…”

Section: Introductionmentioning

confidence: 99%

Effect of Oxygen on Hydrogen Diffusivity in hcp-Zirconium

Liyanage,

Miller,

Rajapakse

2019

Preprint

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Zirconium and its alloys are extensively used as cladding material in nuclear reactors. They are vulnerable to hydrogen degradation under the harsh service conditions of the reactors, which necessitates continuous monitoring for the hydride concentration. The presence of hydride denuded zones in the latter stages of the pressure tube's life hinders the monitoring process, which is carried out by scrape samples taken from the surface of pressure tubes. We investigated the effect of oxygen on diffusivity of hydrogen in α Zr, to check the hypothesis that oxygen slows the diffusion of hydrogen and thereby encourages the occurrence of hydride denuded zones. From the study we found that oxygen indeed decreases the diffusivity of hydrogen in α Zr for moderate O concentrations, supporting the hypothesis. We investigated the diffusion processes of individual H atoms, which showed that the reduction in diffusivity is caused by a decrease in the hopping rates and the formation of hydrogen traps by the combination of several interstitial sites.

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Hydride Induced Degradation of Mechanical Properties of Zr-2.5Nb Alloy

Singh

2024

Springer Proceedings in Physics

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Delayed hydride cracking of Zr-2.5%Nb pressure tube material due to partially constrained precipitates

Cited by 25 publications

References 49 publications

Denuded zones in zirconium pressure vessels: oxygen’s role examined via multi-scale diffusion model

Denuded zones in zirconium pressure vessels: oxygen’s role examined via multi-scale diffusion model

Effect of Oxygen on Hydrogen Diffusivity in hcp-Zirconium

Hydride Induced Degradation of Mechanical Properties of Zr-2.5Nb Alloy

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