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Title: Micro to nanostructural observations in neutron irradiated nuclear graphites PCEA and PCIB

Here, the neutron irradiation induced structural changes in nuclear grade graphites PCEA and PCIB were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). The graphite samples were irradiated at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. Received doses ranged from 1.5 dpa - 6.8 dpa and irradiation temperatures varied between 350°C - 670°C. XRD data showed crystallite sizes to reduce by 35% (for both La and Lc) for low dose, low temperature specimens and by 50% (for both La and Lc) for high dose, high temperature specimens (compared to unirradiated specimens of the same grade). Analysis of the G peak in Raman spectra of irradiated specimens provided evidence for the fragmentation of crystallites following neutron irradiation. Conventional TEM and SAED were used to observe the structure of lattice fringes and measure the spacing of planes. Image analysis software was applied to TEM images to quantify fringe length, tortuosity, and relative orientation of planes. Neutron irradiation appeared to induce basal plane fragmentation and curvature. EELS was performed to study the proportion of sp2 bonding and specimen density. Themore » high dose high temperature specimens showed evidence of structural recovery where sp2 values are slightly higher than values associated with low dose low temperature specimens. Data from XRD, Raman, TEM, SAED and EELS showed that low dose low temperature specimens tended to exhibit higher structural damage (such as lower sp2 content, higher d-spacing, and reduced crystallite size) than high dose high temperature specimens.« less
Authors:
 [1] ; ORCiD logo [2] ; ORCiD logo [3] ;  [2] ;  [2] ; ORCiD logo [2] ;  [2]
  1. GeoForschungsZentrum, Potsdam (Germany); Univ. of Leeds, Leeds (United Kingdom)
  2. Univ. of Leeds, Leeds (United Kingdom)
  3. Idaho National Lab. (INL), Idaho Falls, ID (United States); Center for Advanced Energy Studies, Idaho Falls, ID (United States)
Publication Date:
Grant/Contract Number:
AC07-05ID14517
Type:
Accepted Manuscript
Journal Name:
Journal of Nuclear Materials
Additional Journal Information:
Journal Volume: 491; Journal Issue: C; Journal ID: ISSN 0022-3115
Publisher:
Elsevier
Research Org:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AGC; PCEA; PCIB; Nuclear graphite; microstructure; irradiated
OSTI Identifier:
1465813

Freeman, Helen M., Mironov, B. E., Windes, William E., Alnairi, M. M., Scott, A. J., Westwood, A. V. K., and Brydson, R. M. D.. Micro to nanostructural observations in neutron irradiated nuclear graphites PCEA and PCIB. United States: N. p., Web. doi:10.1016/j.jnucmat.2017.05.011.
Freeman, Helen M., Mironov, B. E., Windes, William E., Alnairi, M. M., Scott, A. J., Westwood, A. V. K., & Brydson, R. M. D.. Micro to nanostructural observations in neutron irradiated nuclear graphites PCEA and PCIB. United States. doi:10.1016/j.jnucmat.2017.05.011.
Freeman, Helen M., Mironov, B. E., Windes, William E., Alnairi, M. M., Scott, A. J., Westwood, A. V. K., and Brydson, R. M. D.. 2017. "Micro to nanostructural observations in neutron irradiated nuclear graphites PCEA and PCIB". United States. doi:10.1016/j.jnucmat.2017.05.011. https://www.osti.gov/servlets/purl/1465813.
@article{osti_1465813,
title = {Micro to nanostructural observations in neutron irradiated nuclear graphites PCEA and PCIB},
author = {Freeman, Helen M. and Mironov, B. E. and Windes, William E. and Alnairi, M. M. and Scott, A. J. and Westwood, A. V. K. and Brydson, R. M. D.},
abstractNote = {Here, the neutron irradiation induced structural changes in nuclear grade graphites PCEA and PCIB were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), selected area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). The graphite samples were irradiated at the Advanced Test Reactor National User Facility at the Idaho National Laboratory. Received doses ranged from 1.5 dpa - 6.8 dpa and irradiation temperatures varied between 350°C - 670°C. XRD data showed crystallite sizes to reduce by 35% (for both La and Lc) for low dose, low temperature specimens and by 50% (for both La and Lc) for high dose, high temperature specimens (compared to unirradiated specimens of the same grade). Analysis of the G peak in Raman spectra of irradiated specimens provided evidence for the fragmentation of crystallites following neutron irradiation. Conventional TEM and SAED were used to observe the structure of lattice fringes and measure the spacing of planes. Image analysis software was applied to TEM images to quantify fringe length, tortuosity, and relative orientation of planes. Neutron irradiation appeared to induce basal plane fragmentation and curvature. EELS was performed to study the proportion of sp2 bonding and specimen density. The high dose high temperature specimens showed evidence of structural recovery where sp2 values are slightly higher than values associated with low dose low temperature specimens. Data from XRD, Raman, TEM, SAED and EELS showed that low dose low temperature specimens tended to exhibit higher structural damage (such as lower sp2 content, higher d-spacing, and reduced crystallite size) than high dose high temperature specimens.},
doi = {10.1016/j.jnucmat.2017.05.011},
journal = {Journal of Nuclear Materials},
number = C,
volume = 491,
place = {United States},
year = {2017},
month = {5}
}