Characterisation of heterogeneities and evaluation of properties of nuclear grade graphite
DOI:
https://doi.org/10.15282/jmes.13.1.2019.11.0381Keywords:
Nuclear grade graphite, microstructural characterization, aspect ratio, theoretical densityAbstract
Graphite is one of the promising candidates to be used in the next-generation first breeder reactors as a moderator against first moving neutron effluence. During interaction with the neutron, substantial change in microstructure and mechanical and thermal properties occur for graphite. This affects its in-reactor performance. The changes depend on the characteristics of as received virgin material. Therefore, it is necessary to characterize as-received graphite accurately. This paper reports the microstructural characterisation of different nuclear graphite. Four different nuclear graphites were obtained from open source through end-user and were examined in the optical microscope. Quantification of microstructural features was carried out by Analysis Five software. A considerable number of pores with cracks were seen within the matrix. The pores and crack size distribution were found in the range of 0-10 µm2 to a 400-1000 µm2 for the investigated samples. The majority of the pores and cracks were seen within the range of 10-100 µm2 area. The total porosity was to the tune of 9.25 - 5.78%. Pores and cracks of a broad variety of the size were found, and which were uniformly distributed. The theoretical density was calculated from the obtained pores and cracks percentage data. There was no correlation found between the pores and the cracks density (no of pores and cracks per mm2) and the theoretical density of the graphite samples. Density was found to be independent of sizes of pores and cracks of nuclear graphite.
References
Zhou X, Tang Y, Lu Z, Zhang J, Liu B. Nuclear graphite for high temperature gas-cooled reactors. New Carbon Materials 2017;32:193–204.
Marsden BJ. Nuclear graphite for high temperature reactors. Gas turbine power conversion systems for modular HTGRs.2001;46:177–92.
Li Z, Chen D, Fu X, Miao W, Zhang Z. The influence of pores on irradiation property of selected nuclear graphites. Advances in Materials Science and Engineering 2012; 2012:1–7.
Burchell TD, Snead LL. The effect of neutron irradiation damage on the properties of grade NBG-10 graphite.Journal of Nuclear Materials 2007;371:18–27.
Burchell TD. Radiation effects in graphite.Comprehensive nuclear materials, Oxford: Elsevier 2012;299–324.
Best JV, Stephen WJ, Wickham AJ.Radiolytic graphite oxidation.Progress in Nuclear Energy 1985;16:127–178.
Brocklehurst JE, Brown RG, Gilchrist KE, Labaton VY.The effect of radiolytic oxidation on the physical properties of graphite. Journal of Nuclear Materials 1970;35:183-194.
Wen K, Marrow J, Marsden B. Microcracks in nuclear graphite and highly oriented pyrolytic graphite (HOPG). Journal of Nuclear Materials 2008;381:199–203.
Berre C,Mummery PM,Marsden BJ,Mori T,Withers PJ.Application of micromechanics model to the overall properties of heterogeneous graphite.Journal of Nuclear Materials 2008;381:124-128.
Li Z,Chen D,Fu X,Miao W,Zhang Z.The influence of pores on irradiation property of selected nuclear graphites. Advances in Materials Science and Engineer 2012;2012:1–7.
Berre C, Fok SL, Mummery PM, Ali J, Marsden BJ, Marrow TJ, Neighbour GB. Failure analysis of the effects of porosity in thermally oxidized nuclear graphite using finite element modeling. Journal of Nuclear Materials 2008;381:1–8.
Babout L,Marsden BJ,Mummery PM,Marrow TJ.Three-dimensional characterization and thermal property modelling of thermally oxidized nuclear graphite. Acta Materialia 2008;56:4242–4254.
Berre C, Fok SL, Marsden BJ, Babout L, Hodgkins A, Marrow TJ, Mummery PM. Numerical modelling of the effects of porosity changes on the mechanical properties of nuclear graphite.Journal of Nuclear Materials 2006;352:1–5.
Eto M, Oku T, Konishi T. High temperature Young's modulus of a fine-grained nuclear graphite oxidised or prestressed to various levels. Carbon.1991; 29:11-21.
Mao ZQ, Zhang C, Xiao L. A NMR-based porosity calculation method for low porosity and low permeability gas reservoir.Oil Geophysics. Prospect 2010;45:105–109.
Zauer M, Pfriem A, Wagenfuhr A. Toward improved understanding of the cell wall density and porosity of wood determined by gas pycnometry.Wood Science Technology 2013; 47:1197–1211.
Sing K. Adsorption methods for the characterisation of porous materials. Advances in Colloid and Interface Science1998;76–77:3–11.
Burchell TD. A microstructure-based fracture model for polygranular graphite. Carbon 1996;34:297-316.
Martin WD, Putman BJ, Kaye NB.Using image analysis to measure the porosity distribution of a porous pavement.Construction and Building Materials 2013;48:210-217.
Hodgkins A, Marrow TJ, Mummery P, Marsden B, Fok A. X-Ray tomography observation of crack propagation in nuclear graphite. Material Science and Technology 2006; 22:151–1045.
Babout L, Marrow TJ, Mummery PM, Withers PJ. Mapping the evolution of density in 3D of thermally oxidized graphite for nuclear applications.Scripta Materialia 2006;54: 829.
Jones AN, Hall GN, Joyce M, Hodgkins A, Wen K, Marrow TJ. Microstructural characterisation of nuclear grade graphite. Journal of Nuclear materials 2008; 381:152–7.
Wen KY, Marrow TJ, Marsden BJ. The microstructure of nuclear graphite binders. Carbon 2007; 46:62–71.
Kane J, Karthik C, Butt DP, Windes WE, Ubic R. Microstructural characterization and pore structure analysis of nuclear graphite. Journal of Nuclear Materials 2011; 415:189–197.
Wen K, Marrow J, Marsden B. Microcracks in nuclear graphite and highly oriented pyrolytic graphite (HOPG). Journal of Nuclear Materials 2008;381:199-203.
Chi SH, Kim GC. Comparison of 3 MeV C+ion-irradiation effects between the nuclear graphites made of pitch and petroleum cokes.Journal of Nuclear Materials 2008;381:98–105.
Downloads
Published
How to Cite
Issue
Section
License
Copyright (c) 2019 The Author(s)
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
