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Effects of Displacing Radiation on Graphite Observed Using in situ Transmission Electron Microscopy

Hinks, J. A., Jones, A.N. and Donnelly, S. E. (2012) Effects of Displacing Radiation on Graphite Observed Using in situ Transmission Electron Microscopy. MRS Proceedings, 1383. ISSN 1946-4274

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    Abstract

    Graphite is used as a moderator and structural component in the United Kingdom’s fleet
    of Advanced Gas-Cooled Reactors (AGRs) and features in two Generation IV reactor concepts:
    the Very High Temperature Reactor (VHTR) and the Molten Salt Reactor (MSR). Under the
    temperature and neutron irradiation conditions of an AGR, nuclear-grade graphite demonstrates
    significant changes to it mechanical, thermal and electrical properties. These changes include
    considerable dimensional change with expansion in the c-direction and contraction in the a/bdirections.
    As the United Kingdom’s AGRs approach their scheduled decommissioning dates, it
    is essential that this behaviour be understood in order to determine under what reactor conditions
    their operating lifetimes can be safely extended.
    Two models have been proposed for the dimensional change in graphite due to displacing
    radiation: the “Standard Model” and “Ruck and Tuck”. The Standard Model draws on a
    conventional model of Frenkel pair production, point defect migration and agglomeration but
    fails to explain several key experimental observations. The Ruck and Tuck model has been
    proposed by M.I. Heggie et al. and is based upon the movement of basal dislocation to create
    folds in the “graphene” sheets and seeks not only to account for the dimension change but also
    the other phenomena not explained by the Standard Model.
    In order to test the validity of these models, work is underway to gather experimental
    evidence of the microstructural evolution of graphite under displacing radiation. One of the
    primary techniques for this is transmission electron microscopy with in situ ion irradiation. This
    paper presents the results of electron irradiation at a range of energies (performed in order to
    separate the effects of the electron and ion beams) and of combined electron and ion beam
    irradiation.

    Item Type: Article
    Subjects: Q Science > Q Science (General)
    Q Science > QC Physics
    Schools: School of Computing and Engineering
    School of Computing and Engineering > Pedagogical Research Group
    School of Computing and Engineering > Electron Microscopy and Materials Analysis
    Related URLs:
    Depositing User: Jonathan Hinks
    Date Deposited: 27 Nov 2012 16:29
    Last Modified: 02 Sep 2013 11:25
    URI: http://eprints.hud.ac.uk/id/eprint/16011

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