Assessment of the fracture toughness of neutron-irradiated nuclear graphite by 3D analysis of the crack displacement field

Xiaochao Jin, James Wade-Zhu, Yang Chen, Paul M. Mummery, Xueling Fan, T. James Marrow

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18 Citations (SciVal)


Digital volume correlation of in situ synchrotron X-ray computed tomographs has been used to measure the three-dimensional displacement fields around quasi-static propagating cracks in neutron irradiated and unirradiated graphite in specimens of the double cleavage drilled compression geometry. The crack tip location and crack opening were extracted from the displacement fields using a phase congruency edge detection method as cracks were propagated over ∼5 mm. The cracks propagated in mode I, maintaining a constant crack opening angle that was ∼50% smaller for the irradiated graphite. 3D finite element simulations, using the measured full field displacements as boundary conditions, obtained the critical elastic strain energy release rate for crack propagation by calculation of the domain contour J-integral. When the non-linear properties of unirradiated graphite were considered, the strain energy release rate for propagation was constant (180 ± 22 Jm-2) with increasing crack length. The irradiated graphite (fluence of 19.7 × 1020 neutrons cm−2 or 2.6 dpa, 4% weight loss by radiolytic oxidation) had linear elastic properties, and the strain energy release rate for propagation increased linearly from 118 ± 12Jm-2 to 485 ± 75 Jm-2 with crack length.

Original languageEnglish
Pages (from-to)882-893
Number of pages12
Early online date28 Sept 2020
Publication statusPublished - 31 Jan 2021

Bibliographical note

Funding Information:
Two authors (JW/PMM) were supported through IUK Grant TS/M007723/1 “Influence of Creep and Geometry on Strength of Irradiated Graphite Components”. X-C Jin gratefully acknowledges the support of the China Scholarship Fund (Award No. 201806280383 ) that enabled his participation in this work. The experimental data were obtained in beamtime awarded for experiment MT16668 at the Diamond-Manchester Imaging Branchline I13-2 at the Diamond Light Source (Didcot, UK). The materials were provided by EDF Energy Ltd (Barnwood) and machined at NNL (UK National Nuclear Laboratory). The software and workstation used for the digital volume correlation analysis was supported by EPSRC Grant EP/M02833X/1 “University of Oxford: experimental equipment upgrade”.

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)


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