Influence of size distribution of Zr(Fe, Cr)2 precipitates on hydrogen transport through oxide film of Zircaloy-4

Hatano, Yuji; Hitaka, R.; Sugisaki, Masayasu; Hayashi, Masataka

doi:10.1016/s0022-3115(97)00128-1

Cited by 28 publications

(17 citation statements)

References 9 publications

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“…It was associated with pure chromia Cr 2 O 3 . The local development of Fe and Cr oxide precipitates is in good agreement with the fact that iron and chromium present in Zircaloy-4 are known to form intermetallic Laves-phases c-Zr(Fe,Cr) 2 [1][2][3]37]. Moreover, the detection of these three 'pure' phases in the zirconia matrix could be understood as the result of the successive oxidation of iron and chromium depending on the scale thickness and on the oxygen chemical potential value as it was showed by Pêcheur et al [3].…”

Section: Resultssupporting

confidence: 62%

“…Moreover, the evolution of these intermetallic precipitates during oxidation of the zirconium alloy was little studied and is still controversial. Some authors claim that Zr(Fe,Cr) 2 precipitates oxidise in service [1] while others affirm that they remain unoxidised in the oxide film [2]. It was even assumed by Pêcheur et al [3] that precipitates remain unoxidised in the inner part of the zirconia scale while they oxidise in the outer part where the oxygen chemical potential is high enough.…”

Section: Introductionmentioning

confidence: 99%

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Comparative study and imaging by PhotoElectroChemical techniques of oxide films thermally grown on zirconium and Zircaloy-4

Benaboud¹,

Bouvier²,

Petit³

et al. 2007

Journal of Nuclear Materials

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Section: Resultssupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Comparative study and imaging by PhotoElectroChemical techniques of oxide films thermally grown on zirconium and Zircaloy-4

Benaboud¹,

Bouvier²,

Petit³

et al. 2007

Journal of Nuclear Materials

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“…Based on observations of tritium segregation to some precipitates [137,142], many authors [137,146,147] argue that intermetallic precipitates in zircaloy could be paths for short-circuit diffusion due to large reported values for solubility and diffusivity in some of these phases. However, these quantities appear to be relatively large for the Zr-matrix material.…”

Section: < Figure 17 Here>mentioning

confidence: 99%

Tritium Barriers and Tritium Diffusion in Fusion Reactors

Causey

Karnesky

Marchi

2012

Comprehensive Nuclear Materials

132

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Tritium and deuterium induce radiation in reactor materials and some radioactive tritium gas may be released. Most of the materials used in fusion reactors are metals that have relatively high permeabilities for tritium. The fusion community has been working on barriers to minimize tritium release. Unfortunately, most barrier materials work very well during laboratory experiments, but fail to meet requirements when placed in radiation environments.This chapter presents tritium permeation characteristics of various materials used in fusion reactors, including plasma-facing, structural, and barrier materials. The necessary parameters for tritium release calculations for various regions of a fusion reactor are given.

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“…The detailed procedures of heat treatment were described in the previous paper. 3 The former specimen wilI be hereafter described as specimen A and the latter as specimen B. In the specimen A, the diameter of precipitates was less than 50 nm.…”

Section: Introduction Experimentalmentioning

confidence: 99%

Transport mechanism of hydrogen through oxide film formed on zircaloy-4

Hatano

Hitaka

Sugisaki

et al. 1999

J Radioanal Nucl Chem

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The diffusion behavior of hydrogen in the oxide films of zircaloy-4 specimens containing different size of Zr(Fe,Cr) 2 precipitates was examined. In the case of the specimen containing fine precipitates, hydrogen diffused uniformly through the zirconium oxide phase. The diffusion coefficient was 2-10 -25 m 2-s-~ at room temperature and 6-10 -19 m L s -z at 673 K. The transport rate of hydrogen in the oxide film of the specimen containing coarse precipitates was significantly higher than that of the specimen containing fine ones at both room temperature and 673 K. Introduction ExperimentalThe hydrogen uptake behavior of zircaloy is an important problem to evaluate the performance of fuel claddings of water-cooled reactors. It is well known that the hydrogen uptake behavior of zircaloy is strongly dependent on its alloy composition and heat treatments during fabrication.l In order to investigate the mechanism of influence of heat treatments, we have recently examined the influence of size distribution of intermetallic precipitates, such as Zr(Fe,Cr)2 and Zr2(Fe,Ni) in zircaloy-2 and Zr(Fe,Cr) 2 in zircaloy-4, on the hydrogen uptake behavior of zircaloy during oxidation in steam and found out that the specimen containing coarse precipitates took up larger amount of hydrogen than the specimen containing fine ones. 2,3 The influence of the precipitate size on the hydrogen transport in the oxide film, however, has not been fully clarified.In the present study, the diffusion behavior of hydrogen in the oxide films of two different types of zircaloy-4 specimens containing fine and coarse Zr(Fe,Cr)2 precipitates was examined at high temperature (673 K) and room temperature. In the former case, the specimens were oxidized in D20 steam, and the depth profile of deuterium was measured with secondary ion mass spectroscopy (SIMS). The secondary ion yield of deuterium was calibrated by measuring the radioactivity of tritium in the oxide film with a liquid scintillation counter. In the latter case, the diffusion coefficient of tritium in the oxide film was estimated from the leaching rate of tritium into the scintillation cocktail. The mechanism of the influence of precipitate size on the hydrogen transport in the oxide film is discussed.The alloy composition of zircaloy-4 used in the present study is shown in Table 1. Two disk-type specimens (8.5 mm in diameter, 3 mm in thickness) containing fine and coarse Zr(Fe,Cr) 2 precipitates were prepared with heat treatments. The detailed procedures of heat treatment were described in the previous paper. 3 The former specimen wilI be hereafter described as specimen A and the latter as specimen B. In the specimen A, the diameter of precipitates was less than 50 nm. 3 In the specimen B, the average and maximum diameter of precipitates were 0.5 and 1.7gm, respectively. 3 The specimens were mechanically polished with abrasive paper and finished by polishing with 0.3 gm A1203 powder.The specimens were oxidized in H20 steam at 673 K and 0.1 MPa, and a coherent oxide film whose thickness was 1...

show abstract

Influence of size distribution of Zr(Fe, Cr)2 precipitates on hydrogen transport through oxide film of Zircaloy-4

Cited by 28 publications

References 9 publications

Comparative study and imaging by PhotoElectroChemical techniques of oxide films thermally grown on zirconium and Zircaloy-4

Comparative study and imaging by PhotoElectroChemical techniques of oxide films thermally grown on zirconium and Zircaloy-4

Tritium Barriers and Tritium Diffusion in Fusion Reactors

Transport mechanism of hydrogen through oxide film formed on zircaloy-4

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