Crack initiation and propagation in pile grade A (PGA) reactor core graphite under a range of loading conditions

Heard, Peter J; Wootton, M.R.; Moskovic, R.; Flewitt, Peter E J

doi:10.1016/j.jnucmat.2010.03.023

Cited by 22 publications

(24 citation statements)

References 11 publications

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“…Approaches focussed on reducing the size of the irradiated test specimens give rise to a range of miniaturised specimens tested using different geometrical arrangements. In the specific case of irradiated nuclear graphites, smaller lengthscale tests, such as the mm-scale Brazilian disc geometry test, have been adopted by Heard et al [22]. However, the latter authors provided only final failure load for the one macroscopic graphite specimen tested [22].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

“…In the specific case of irradiated nuclear graphites, smaller lengthscale tests, such as the mm-scale Brazilian disc geometry test, have been adopted by Heard et al [22]. However, the latter authors provided only final failure load for the one macroscopic graphite specimen tested [22]. By adopting focussed ion beam milling, it has been possible to explore a wide range of micro-scale geometry specimens that have been tested to measure mechanical properties [19][23] [15][10] [18].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

“…By adopting focussed ion beam milling, it has been possible to explore a wide range of micro-scale geometry specimens that have been tested to measure mechanical properties [19][23] [15][10] [18]. One of the first applications that invoked gallium ion milling to prepare irradiated graphite specimens in a focussed ion beam (FIB) workstation and then conducting an in situ trench-probe test, was described by Heard et al [22]. During that particular test, the specimen was moved towards a fixed probe, the localised fracture of irradiated PGA graphite was observed but no outputs of load or displacement were provided.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

See 2 more Smart Citations

Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing

Liu

Flewitt

2017

Carbon

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing AbstractThe local mechanical properties of vitreous carbon and another three porous graphite materials have been investigated using a novel in situ micro-cantilever bending approach.Vitreous carbon is used for validation of the micro-mechanical measurements. Filter graphite is a single phase material with ~52 vol.% porosity. Gilsocarbon graphite is a nuclear-grade graphite that is currently used in the advanced gas-cooled reactors in the UK with ~20 vol.% porosity in the filler particles and matrix; Pile Grade-A graphite (PGA) was extracted from a fuel brick within a Magnox reactor core with 15% weight loss due to neutron irradiation and CO 2 radiolytic oxidation. The 'true' material properties obtained at micro-scale are found to be of much higher value than those measured at the macro-scale due to different failure controlling mechanisms. In particular for the PGA graphite, the micro-mechanical tests allowed the mechanical properties of the filler particles and matrix to be measured separately.The filler particles showed a higher stiffness and flexural strength compared with the matrix indicating the different influence of neutron irradiation on these two constituents. It is demonstrated here that the local mechanical properties of carbonaceous materials with various complex microstructures and even following neutron irradiation can be successfully evaluated.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

See 1 more Smart Citation

Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing

Liu

Flewitt

2017

Carbon

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“…One of the main difficulties in determining the fracture characteristics by conventional fracture mechanics methodologies is that graphite is a highly brittle material. Many researchers [1,[3][4][5][6][7][8][9][10][11] have attempted various standard techniques to determine fracture properties, however, report difficulty in propagating cracks controllably [12]. This paper employs an alternate method, which facilitates stable crack growth using the so called Double Torsion (DT) technique.…”

Section: Introductionmentioning

confidence: 99%

Damage, crack growth and fracture characteristics of nuclear grade graphite using the Double Torsion technique

Becker

Marrow

Tait

2011

Journal of Nuclear Materials

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“…Fracture criteria such as maximum stress [1], maximum strain [2] and maximum energy [3] have been proposed; the maximum stress approach has been adopted by the UK community but it is considered to be conservative. Where the complexity lies is that these polygranular aggregate graphites show quasi-brittle characteristics when deform and fracture [4], i.e. there is a non-linear stage prior to final failure.…”

Section: Introductionmentioning

confidence: 99%

Multi-scale characterization and modelling of damage evolution in nuclear Gilsocarbon graphite

et al. 2015

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In the present work, the microstructure and mechanical properties of Gilsocarbon graphite have been characterized over a range of length-scales. Optical imaging, combined with 3D X-ray computed tomography and 3D high-resolution tomography based on focus ion beam milling has been adopted for microstructural characterization. A range of small-scale mechanical testing approaches are applied including an in situ micro-cantilever technique based in a Dualbeam workstation. It was found that pores ranging in size from nanometers to tens of micrometers in diameter are present which modify the deformation and fracture characteristics of the material. This multi-scale mechanical testing approach revealed the significant change of mechanical properties, for example flexural strength, of this graphite over the length-scale from a micrometer to tens of centimeters. Such differences emphasize why input parameters to numerical models have to be undertaken at the appropriate length-scale to allow predictions of the deformation, fracture and the stochastic features of the strength of the graphite with the required confidence. Finally, the results from a multi-scale model demonstrated that these data derived from the micro-scale tests can be extrapolated, with high confidence, to large components with realistic dimensions.

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Crack initiation and propagation in pile grade A (PGA) reactor core graphite under a range of loading conditions

Cited by 22 publications

References 11 publications

Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing

Deformation and fracture of carbonaceous materials using in situ micro-mechanical testing

Damage, crack growth and fracture characteristics of nuclear grade graphite using the Double Torsion technique

Multi-scale characterization and modelling of damage evolution in nuclear Gilsocarbon graphite

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