Analysis of the dimensional changes and structural changes in polycrystalline graphite under fast neutron irradiation

Brocklehurst, J.E.; Kelly, Brian

doi:10.1016/0008-6223(93)90169-b

Cited by 85 publications

(62 citation statements)

References 6 publications

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“…Thus only at higher temperatures such as those in the Gen IV graphite moderated Very High Temperature Gas Reactors (> 300 °C) does stored energy dissipation occur by diffusion driven atomic re-ordering and the problem is addressed in the short term. Longer term exposure to a high temperature environment (> 400 °C) however, gives rise to creep and dimensional change [18][19][20].…”

Section: Irradiation Of Nuclear Graphitementioning

confidence: 99%

Electron irradiation of nuclear graphite studied by transmission electron microscopy and electron energy loss spectroscopy

Mironov

Freeman

Brown

et al. 2015

Carbon

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Structural and chemical bonding changes in nuclear graphite have been investigated during in-situ electron irradiation in a transmission electron microscope (TEM); electron beam irradiation has been employed as a surrogate for neutron irradiation of nuclear grade graphite in nuclear reactors. This paper aims to set out a methodology for analysing the microstructure of electron-irradiated graphite which can then be extended to the analysis of neutron-irradiated graphites. The damage produced by exposure to 200 keV electrons was examined up to a total dose of approximately 0.5 dpa (equivalent to an electron fluence of 5.6x 10 21 electrons cm -2 ). During electron exposure, high resolution TEM images and electron energy loss spectra (EELS) were acquired periodically in order to record changes in structural (dis)order and chemical bonding, by quantitatively analysing the variation in phase contrast images and EEL spectra.

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Section: Irradiation Of Nuclear Graphitementioning

confidence: 99%

Electron irradiation of nuclear graphite studied by transmission electron microscopy and electron energy loss spectroscopy

Mironov

Freeman

Brown

et al. 2015

Carbon

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“…83 The cumulative closure of this accommodation plus other structure effects will enhance the influence of the crystal c-axis dimensional changes. Thus equation (21) has been modified by the inclusion of an influence function 'F' (a function of both fluence and temperature) to give: 80 ). c Prediction using equation (22).…”

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confidence: 99%

“…Fit defined using the exact function and a simplified version of 'F', along with the experimental irradiation data at 600°C. 80 d Prediction using equation (22). Fit defined using the exact and a simplified version of 'F' along with the experimental irradiation data at 430°C 80 26 Influence functions 'F' for Gilsocarbon specimens irradiated at 430°C and 600°C 80 and ATR-2E 7 creep control specimens irradiated to 500°C The function F has been obtained by fitting curves to the Gilsocarbon irradiation data 80 and the appropriate HOPG experimental data 79 and then iterating between equation (22) …”

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confidence: 99%

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

Marsden

Haverty

Bodel

et al. 2016

International Materials Reviews

106

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Since the start of the 'nuclear age' graphite has been employed as a moderator in around 100 nuclear reactors, and today there are still some 30 graphite-moderated reactors operating and there are plans for new Generation IV high-temperature reactors. Many of the graphite moderator reactors now producing power are operating beyond their original design life. Therefore in some cases, to aid the reactor operators and designers, the existing graphite irradiation databases need to be extended either to a higher temperature or higher neutron fluence. Furthermore, data are needed for the different grades of graphite that are available at present. This can either be achieved by expensive, time consuming irradiation programmes or by improving the understanding of the mechanisms and processes which lead to irradiationinduced dimensional and property changes in the graphite core components. This review looks at three of the most important graphite properties which change with exposure to irradiation, namely dimensional change, irradiation creep and thermal expansion. The behaviour of UK AGR, Magnox and an experimental grade of German reactor graphite are explored in some detail. First graphite reactor core design is briefly discussed, giving examples of typical graphite components and core arrangements. Issues related to aging graphite component and core behaviour are illustrated through examples of component internal and thermal stress generation, and issues related to whole core behaviour are also outlined. Second the manufacture and microstructure of different nuclear graphite grades are discussed, highlighting how the choice of raw materials and manufacturing technique influences the graphite properties. Third the coefficient of thermal expansion, dimensional change and irradiation creep are analysed using microstructural and averaging methods which are used to relate crystal to bulk properties by accounting for graphite crystal orientation and porosity. These techniques, which were first applied to nuclear graphite in the 1960s, are extended and discussed with the aim of trying to lend some understanding to the role the microstructural crystallite and porosity distributions play in defining the dimensional stability and properties of virgin graphite, irradiated graphite and stressed graphite.

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“…[13][14][15][16][17][18] The increase of thermal resistance due to irradiation damage has been ascribed to the formation of the following: (1) submicroscopic interstitial clusters containing 4 ± 2 carbon atoms; (2) vacant lattice sites, existing as singles, pairs, or small groups; and …”

Section: Thermal Properties Of Irradiated Graphite Foammentioning

confidence: 99%

Solid State Reactor Final Report

Mays¹

2004

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Analysis of the dimensional changes and structural changes in polycrystalline graphite under fast neutron irradiation

Cited by 85 publications

References 6 publications

Electron irradiation of nuclear graphite studied by transmission electron microscopy and electron energy loss spectroscopy

Electron irradiation of nuclear graphite studied by transmission electron microscopy and electron energy loss spectroscopy

Dimensional change, irradiation creep and thermal/mechanical property changes in nuclear graphite

Solid State Reactor Final Report

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