Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields

doi:10.1016/j.jnucmat.2018.09.008

Title: Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields

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Abstract

Graphite is a candidate material for Generation IV concepts and is used as a moderator in Advanced Gas-cooled Reactors (AGR) in the UK. Spatial material variability is present within billets causing different material property values between different components. Variations in material properties and irradiation effects can produce stress concentrations and diverse mechanical responses in a nuclear reactor graphite core. In order to characterise the material variability, geostatistical techniques called variography and random field theory were adapted for studying the density and Young's modulus of a billet of Gilsocarbon and NBG-18 graphite grades. Variography is a technique for estimating the distance over which material property values have significant spatial correlation, known as the scale of fluctuation or spatial correlation length. The paper uses random field theory to create models that mimic the original spatial and statistical distributions of the original data set. This study found different values of correlation length for density and Young's modulus around the edges of a Gilsocarbon billet, while in the case of NBG-18, similar correlation lengths where found across the billet. Furthermore examples of several random fields are given to reproduce the spatial patterns and values found in the original data.

Authors:

^[1];

^[1]; Margetts, Lee ^[2]; Griffiths, D. V. ^[3]; Windes, William E. ^[4]; Carroll, Mark ^[4];

^[2]

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. of Manchester, Manchester (United Kingdom)
Colorado School of Mines, Golden, CO (United States)
Idaho National Lab. (INL), Idaho Falls, ID (United States)

Publication Date:: 2018-09-08

Research Org.:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1479781

Grant/Contract Number:: AC05-00OR22725

Resource Type:: Accepted Manuscript

Journal Name:: Journal of Nuclear Materials

Additional Journal Information:: Journal Volume: 511; Journal Issue: C; Journal ID: ISSN 0022-3115

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE

Citation Formats


                    Arregui-Mena, José David, Edmondson, Philip D., Margetts, Lee, Griffiths, D. V., Windes, William E., Carroll, Mark, and Mummery, Paul M. Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields.  United States: N. p., 2018. 
        Web.  doi:10.1016/j.jnucmat.2018.09.008.

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                    Arregui-Mena, José David, Edmondson, Philip D., Margetts, Lee, Griffiths, D. V., Windes, William E., Carroll, Mark, & Mummery, Paul M. Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields.  United States.  doi:10.1016/j.jnucmat.2018.09.008.

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                    Arregui-Mena, José David, Edmondson, Philip D., Margetts, Lee, Griffiths, D. V., Windes, William E., Carroll, Mark, and Mummery, Paul M. Sat .  
        "Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields".  United States.  doi:10.1016/j.jnucmat.2018.09.008.  https://www.osti.gov/servlets/purl/1479781.

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@article{osti_1479781,

  title        = {Characterisation of the spatial variability of material properties of Gilsocarbon and NBG-18 using random fields},

  author       = {Arregui-Mena, José David and Edmondson, Philip D. and Margetts, Lee and Griffiths, D. V. and Windes, William E. and Carroll, Mark and Mummery, Paul M.},

  abstractNote = {Graphite is a candidate material for Generation IV concepts and is used as a moderator in Advanced Gas-cooled Reactors (AGR) in the UK. Spatial material variability is present within billets causing different material property values between different components. Variations in material properties and irradiation effects can produce stress concentrations and diverse mechanical responses in a nuclear reactor graphite core. In order to characterise the material variability, geostatistical techniques called variography and random field theory were adapted for studying the density and Young's modulus of a billet of Gilsocarbon and NBG-18 graphite grades. Variography is a technique for estimating the distance over which material property values have significant spatial correlation, known as the scale of fluctuation or spatial correlation length. The paper uses random field theory to create models that mimic the original spatial and statistical distributions of the original data set. This study found different values of correlation length for density and Young's modulus around the edges of a Gilsocarbon billet, while in the case of NBG-18, similar correlation lengths where found across the billet. Furthermore examples of several random fields are given to reproduce the spatial patterns and values found in the original data.},

  doi          = {10.1016/j.jnucmat.2018.09.008},

  journal      = {Journal of Nuclear Materials},

  number       = C,

  volume       = 511,

  place        = {United States},

  year         = {2018},

  month        = {9}

}

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