首页|The effect of radiolytic oxidation on the elastic properties of nuclear graphite measured by electronic speckle pattern interferometry

The effect of radiolytic oxidation on the elastic properties of nuclear graphite measured by electronic speckle pattern interferometry

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  • NSTL
  • Elsevier
The Young's modulus, Poisson's ratio and flexural strength of 218 beams of radiolytically oxidised nu-clear graphite have been determined by combining electronic speckle pattern interferometry, ESPI, and inverse finite element modelling techniques. The graphite was extracted from three operational advanced gas cooled reactor stations where it had been subjected to fast neutron irradiation and radiolytic oxi-dation resulting in mass loss. The 6 x 6 x 19 mm beam samples had densities ranging from 1063 - 1840 kg.m( -3), equivalent to weight losses up to 46%, with cumulative neutron doses of up to 161 x 10 20 n.cm -2 equivalent Dido nickel dose, or 21.1 displacements per atom, significantly extending the datasets available in the open literature to higher levels of both dose and oxidation. In situ ESPI measurements were collected during three-point bend tests, creating full field displacement maps of the evolving de-formation to which simulations were matched by chi-squared minimisation of the elastic properties. Po-tential loading abnormalities were accounted for in the fitting process to ensure the simulations were representative, with total uncertainties in the determined Young's modulus and Poisson's ratio values of +/- 4.5% and +/- 0.08, respectively. Consistent trends were observed in the behaviour of the material from the different stations, with strong positive dependences on density for both the flexural strength and Young's modulus. The strength and Young's modulus remained well correlated even to high levels of ox-idation mass loss. Conversely, the Poisson's ratio was practically invariant with oxidation with mean val-ues of 0.21 +/- 0.03, 0.24 +/- 0.05 and 0.25 +/- 0.05 for the three stations. The combined ESPI-finite element measurement approach is demonstrated as robust for irradiated small specimens, making it suitable for monitoring graphite in future reactors. The collected data support the safety assessments of the current reactors, enabling predictions of the responses to progressively higher mean core mass loss. (C)& nbsp;2021 Elsevier B.V. All rights reserved.

Young's modulusPoisson's ratioFlexural strengthNuclear graphiteGilsocarbonNeutron irradiationRadiolytic oxidationThree-point bendElectronic speckle pattern interferometry & nbsp& nbsp(ESPI)Finite element (FE) simulationNon-linear least squares fittingMODULUS

Shaw, Tim L. L.、Jordan, Matthew S. L.、Wilkinson, Samantha、Ramsay, Paul G.、Gravenor, John G.、Brown, Matthew、Davies, Bruce、Tzelepi, Athanasia

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Natl Nucl Lab

EDF

2022

10.1016/j.jnucmat.2021.153434

Journal of Nuclear Materials

Journal of Nuclear Materials

EISCI
ISSN：0022-3115
年,卷(期)：2022.559
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