Hydride platelet reorientation in zircaloy studied with synchrotron radiation diffraction

Kimberly B. Colas, Arthur T. Motta, Mark R. Daymond, Matthew Kerr, Jonathan D. Almer

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Hydrogen ingress into zirconium alloy fuel cladding in light water reactors can degrade cladding performance as a result of the formation of brittle hydrides. In service, hydrides normally precipitate in the circumferential direction and are homogeneously distributed through the cladding thickness in ideal cases. However, temperature and stress gradients in the cladding can promote hydrogen redistribution. This hydrogen redistribution is responsible for the formation of hydride rims, dissolution, and reorientation of hydride precipitates and for the formation of brittle hydrides at stress concentration locations, all of which can reduce cladding resistance to failure. Thus, it is crucial to understand the kinetics of hydride dissolution and precipitation under load and at temperature. Studies of hydrogen behavior in zirconium alloys are normally performed post facto, which causes them to suffer both from a scarcity of data points and from the confounding effects of studying hydrides at room temperature that might be dissolved at higher temperature. In the current study, we have used synchrotron radiation diffraction to study the kinetics of hydride precipitation and dissolution in situ (under load and at temperature). Samples of hydrided Zircaloy-4 were examined in transmission by using 80 keV synchrotron radiation while undergoing heating and cooling in a furnace. Temperatures ranged from 20 to 550C, and loads from 75 to 100 MPa were applied. The hydrides dissolved and reprecipitated in a different orientation when sufficiently high loads were applied. Through careful study of the intensities and full-width half maxima of the diffraction peaks as a function of time, load, and temperature, it was possible to identify the characteristic diffraction patterns for the reoriented hydrides so that the kinetics of dissolution, reprecipitation, and orientation of the hydrides could be followed. The analysis of the diffraction patterns allowed a detailed understanding of the kinetics of hydride evolution under temperature and stress, as presented in this work.

Original languageEnglish (US)
Title of host publicationZirconium in the Nuclear Industry
Subtitle of host publication16th International Symposium
PublisherASTM International
Pages496-520
Number of pages25
ISBN (Print)9780803175150
DOIs
StatePublished - 2011
Event16th International Symposium on Zirconium in the Nuclear Industry - Chengdu, Sinchuan Province, China
Duration: May 9 2010May 13 2010

Publication series

NameASTM Special Technical Publication
Volume1529 STP
ISSN (Print)0066-0558

Other

Other16th International Symposium on Zirconium in the Nuclear Industry
CountryChina
CityChengdu, Sinchuan Province
Period5/9/105/13/10

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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