The Cause for Enhanced Corrosion of Zirconium Alloys by Hydrides

The Cause for Enhanced Corrosion of Zirconium Alloys by Hydrides PDF Author: HK. Woo
Publisher:
ISBN:
Category : Corrosion
Languages : en
Pages : 23

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Book Description
The cause of the accelerated corrosion of zirconium alloys by hydrides is studied by investigating the corrosion of three section planes of Zr-2.5Nb tubes with different texture: the longitudinal normal section (LS) plane, the transverse normal section (TS) plane, and the radial normal section (RS) plane. Corrosion tests were conducted on those section planes taken from the unhydrided and prehydrided Zr-2.5Nb tubes with up to 450 ppm H in water at 350°C or in steam at 400°C. For Zr-2.5Nb tube with a strong circumferential texture, the deleterious effect of hydrides on enhanced corrosion was most striking on the LS specimen, while beneficial and little hydride effect on the corrosion was observed on the TS and RS specimens, respectively. However, for Zr-2.5Nb tube with a comparatively radial texture, the deleterious effect of hydrides on enhanced corrosion was observed on all the three section planes. The lattice broadening and the interplanar spacing in the zirconium matrix were measured by using X-rays on those section planes taken from Zr-2.5Nb tubes with a circumferential texture before and after charging with hydrogen. The precipitation of hydrides in the Zr-2.5Nb tube subjected the LS plane to residual tensile stress, expanding the zirconium lattice in the LS, and the TS plane to compressive stress, contracting it in the TS. Based on these results, the corrosion acceleration by hydrides is discussed by correlating the change in the zirconium lattice distance or lattice distortion including residual stress and the corrosion on each plane before and after charging with hydrogen. This finding leads us to the conclusion that the major controlling factor to the corrosion of zirconium alloys is the lattice coherency between the metal and the oxide.

The Cause for Enhanced Corrosion of Zirconium Alloys by Hydrides

The Cause for Enhanced Corrosion of Zirconium Alloys by Hydrides PDF Author: HK. Woo
Publisher:
ISBN:
Category : Corrosion
Languages : en
Pages : 23

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Book Description
The cause of the accelerated corrosion of zirconium alloys by hydrides is studied by investigating the corrosion of three section planes of Zr-2.5Nb tubes with different texture: the longitudinal normal section (LS) plane, the transverse normal section (TS) plane, and the radial normal section (RS) plane. Corrosion tests were conducted on those section planes taken from the unhydrided and prehydrided Zr-2.5Nb tubes with up to 450 ppm H in water at 350°C or in steam at 400°C. For Zr-2.5Nb tube with a strong circumferential texture, the deleterious effect of hydrides on enhanced corrosion was most striking on the LS specimen, while beneficial and little hydride effect on the corrosion was observed on the TS and RS specimens, respectively. However, for Zr-2.5Nb tube with a comparatively radial texture, the deleterious effect of hydrides on enhanced corrosion was observed on all the three section planes. The lattice broadening and the interplanar spacing in the zirconium matrix were measured by using X-rays on those section planes taken from Zr-2.5Nb tubes with a circumferential texture before and after charging with hydrogen. The precipitation of hydrides in the Zr-2.5Nb tube subjected the LS plane to residual tensile stress, expanding the zirconium lattice in the LS, and the TS plane to compressive stress, contracting it in the TS. Based on these results, the corrosion acceleration by hydrides is discussed by correlating the change in the zirconium lattice distance or lattice distortion including residual stress and the corrosion on each plane before and after charging with hydrogen. This finding leads us to the conclusion that the major controlling factor to the corrosion of zirconium alloys is the lattice coherency between the metal and the oxide.

Zirconium in the Nuclear Industry

Zirconium in the Nuclear Industry PDF Author: Gerry D. Moan
Publisher: ASTM International
ISBN: 0803128959
Category : Nuclear fuel claddings
Languages : en
Pages : 891

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Book Description
Annotation The 41 papers of this proceedings volume were first presented at the 13th symposium on Zirconium in the Nuclear Industry held in Annecy, France in June of 2001. Many of the papers are devoted to material related issues, corrosion and hydriding behavior, in-reactor studies, and the behavior and properties of Zr alloys used in storing spent fuel. Some papers report on studies of second phase particles, irradiation creep and growth, and material performance during loss of coolant and reactivity initiated accidents. Annotation copyrighted by Book News, Inc., Portland, OR.

Zirconium in the Nuclear Industry: Tenth International Symposium

Zirconium in the Nuclear Industry: Tenth International Symposium PDF Author: A. M. Garde
Publisher: ASTM International
ISBN: 0803120117
Category : Nuclear fuel claddings
Languages : en
Pages : 805

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Enhancement of Aqueous Corrosion of Zircaloy-4 Due to Hydride Precipitation at the Metal-Oxide Interface

Enhancement of Aqueous Corrosion of Zircaloy-4 Due to Hydride Precipitation at the Metal-Oxide Interface PDF Author: AM. Garde
Publisher:
ISBN:
Category : Autoclave corrosion
Languages : en
Pages : 26

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Book Description
Long-term static autoclave corrosion tests were conducted on Zircaloy-4 tube specimens in water at 633 K. The material variables included in this investigation were: annealing parameter range 10-17 to 10-19 h (with Q/R = 40 000 K). fabrication history variation of early and late beta-quenching steps, and final heat treatment variation from several levels of stress-relief-anneal to a recrystallization anneal. Specimens were weighed at intervals of approximately 28 days for a maximum corrosion test exposure of 1160 days. The weight gain data show transitions to an accelerated corrosion rate that became apparent at exposure times greater than 300 days. The transition times varied from 141 to 253 days. Metallographic and scanning electron microscopic examination showed that the metal-oxide interface had an irregular shape and the oxidation front appeared to progress into the metal by fracture of the hydride precipitates at the interface. Hydrogen absorption fractions were calculated for each specimen and were used to estimate the hydrogen level in each specimen at the transition point. The estimated hydrogen levels at transition agreed reasonably with the hydrogen solubility in Zircaloy at 633 K. The results indicate that the corrosion rate acceleration observed in autoclaves at long times is associated with the onset of hydride precipitation and subsequent hydride fracture at the metal-oxide interface. A review of in-reactor corrosion data from the literature reveals that a similar hydride associated corrosion rate acceleration occurs in low oxygen coolant conditions in PWRs and PHWRs. Hydride precipitation at the metal-oxide interface is the probable reason for the correlation between the time of long-term autoclave corrosion rate transition and the in-PWR cladding corrosion resistance. On the basis of the effect of hydrides on the in-reactor corrosion rate, it is suggested that a better ex-reactor corrosion test to simulate the in-PWR corrosion performance would be a water test at 633 K with an imposed heat flux. The effect of hydrides on the corrosion rate is strongly related to the size, distribution, and orientation of the hydrides in the Zircaloy cross section. An alloy development program is suggested to enhance the corrosion resistance of zirconium alloys in PWRs to extended burnups.

Zirconium in the Nuclear Industry

Zirconium in the Nuclear Industry PDF Author:
Publisher:
ISBN:
Category : Nuclear reactors
Languages : en
Pages : 976

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Zirconium in the Nuclear Industry

Zirconium in the Nuclear Industry PDF Author: Craig M. Eucken
Publisher: ASTM International
ISBN: 080311463X
Category : Nuclear fuel claddings
Languages : en
Pages : 794

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Book Description
The proceedings of the Ninth International Symposium on [title], held in Kobe, Japan, November 1990, address current trends in the development, performance, and fabrication of zirconium alloys for nuclear power reactors. the bulk of the most recent work on zirconium alloy behavior has concerned corr

Corrosion of Zirconium Alloys

Corrosion of Zirconium Alloys PDF Author:
Publisher:
ISBN:
Category : Corrosion and anti-corrosives
Languages : en
Pages : 156

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Zirconium in the Nuclear Industry

Zirconium in the Nuclear Industry PDF Author: George P. Sabol
Publisher: ASTM International
ISBN: 0803124066
Category : Nuclear fuel claddings
Languages : en
Pages : 907

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The Oxidation and Corrosion of Zirconium and Its Alloys

The Oxidation and Corrosion of Zirconium and Its Alloys PDF Author: Atomic Energy Research Establishment (Harwell, England). Chemistry Division
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Electrochemical Techniques in Corrosion Science and Engineering

Electrochemical Techniques in Corrosion Science and Engineering PDF Author: Robert G. Kelly
Publisher: CRC Press
ISBN: 9780203909133
Category : Science
Languages : en
Pages : 442

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Book Description
This book describes the origin, use, and limitations of electrochemical phase diagrams, testing schemes for active, passive, and localized corrosion, the development and electrochemical characterization of passivity, and methods in process alteration, failure prediction, and materials selection. It offers useful guidelines for assessing the efficac