Structure–property relations in graphitic pebbles for nuclear applications

William F. Cureton; Tyler J. Gerczak; Grant W. Helmreich; John D. Hunn; Gerald E. Jellison; Hsin Wang; Stephanie M. Curlin; Ryan N. Latta

doi:10.1016/j.nucengdes.2023.112526

Structure–property relations in graphitic pebbles for nuclear applications

William F. Cureton, Tyler J. Gerczak, Grant W. Helmreich, John D. Hunn, Gerald E. Jellison, Hsin Wang, Stephanie M. Curlin, Ryan N. Latta

Research output: Contribution to journal › Article › peer-review

Abstract

This work presents an analytical approach for holistically characterizing graphitic matrix pebbles for nuclear applications whereby the macrostructure, microstructure, and thermophysical properties of pebbles are determined. A systematic sectioning method was applied to several pebbles to describe the regional properties of the samples. Intact matrix-only spheres and sections of spheres fabricated by Kairos Power were characterized via optical imaging, x-ray computed tomography, x-ray diffraction, and ellipsometry to determine 2D and 3D macrostructure and anisotropy. The thermophysical properties of these materials were determined via measurements of density, specific heat, thermal expansion, and thermal diffusivity. The results of this study indicate that the pebble fabrication methods and their resultant effect on microstructure have a nontrivial effect on thermophysical properties, confirming the importance of robust characterization of these components. A discussion of the characterization approach and its applicability to nuclear fuel development activities is also included.

Original language	English
Article number	112526
Journal	Nuclear Engineering and Design
Volume	414
DOIs	https://doi.org/10.1016/j.nucengdes.2023.112526
State	Published - Dec 1 2023

Funding

This work was supported by a Strategic Partnership Project NFE-20-08306 “Characterization Support of the KP-FHR TRISO Fuel Element” funded by Kairos Power LLC . The authors acknowledge Dr. Michael Koehler at the Institute for Advanced Materials & Manufacturing for assistance with XRD measurements as well as the Materials Imaging and Characterization Laboratory personnel, specifically Daniel Newberry and Jason Smith at Oak Ridge National Laboratory for assistance sectioning pebbles and sample preparation.

Funders	Funder number
Kairos Power LLC

Keywords

Graphitic pebbles
Microstructure
Nuclear matrix graphite
Thermophysical properties

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10.1016/j.nucengdes.2023.112526

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title = "Structure–property relations in graphitic pebbles for nuclear applications",

abstract = "This work presents an analytical approach for holistically characterizing graphitic matrix pebbles for nuclear applications whereby the macrostructure, microstructure, and thermophysical properties of pebbles are determined. A systematic sectioning method was applied to several pebbles to describe the regional properties of the samples. Intact matrix-only spheres and sections of spheres fabricated by Kairos Power were characterized via optical imaging, x-ray computed tomography, x-ray diffraction, and ellipsometry to determine 2D and 3D macrostructure and anisotropy. The thermophysical properties of these materials were determined via measurements of density, specific heat, thermal expansion, and thermal diffusivity. The results of this study indicate that the pebble fabrication methods and their resultant effect on microstructure have a nontrivial effect on thermophysical properties, confirming the importance of robust characterization of these components. A discussion of the characterization approach and its applicability to nuclear fuel development activities is also included.",

keywords = "Graphitic pebbles, Microstructure, Nuclear matrix graphite, Thermophysical properties",

author = "Cureton, {William F.} and Gerczak, {Tyler J.} and Helmreich, {Grant W.} and Hunn, {John D.} and Jellison, {Gerald E.} and Hsin Wang and Curlin, {Stephanie M.} and Latta, {Ryan N.}",

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year = "2023",

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doi = "10.1016/j.nucengdes.2023.112526",

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T1 - Structure–property relations in graphitic pebbles for nuclear applications

AU - Cureton, William F.

AU - Gerczak, Tyler J.

AU - Helmreich, Grant W.

AU - Hunn, John D.

AU - Jellison, Gerald E.

AU - Wang, Hsin

AU - Curlin, Stephanie M.

AU - Latta, Ryan N.

PY - 2023/12/1

Y1 - 2023/12/1

N2 - This work presents an analytical approach for holistically characterizing graphitic matrix pebbles for nuclear applications whereby the macrostructure, microstructure, and thermophysical properties of pebbles are determined. A systematic sectioning method was applied to several pebbles to describe the regional properties of the samples. Intact matrix-only spheres and sections of spheres fabricated by Kairos Power were characterized via optical imaging, x-ray computed tomography, x-ray diffraction, and ellipsometry to determine 2D and 3D macrostructure and anisotropy. The thermophysical properties of these materials were determined via measurements of density, specific heat, thermal expansion, and thermal diffusivity. The results of this study indicate that the pebble fabrication methods and their resultant effect on microstructure have a nontrivial effect on thermophysical properties, confirming the importance of robust characterization of these components. A discussion of the characterization approach and its applicability to nuclear fuel development activities is also included.

AB - This work presents an analytical approach for holistically characterizing graphitic matrix pebbles for nuclear applications whereby the macrostructure, microstructure, and thermophysical properties of pebbles are determined. A systematic sectioning method was applied to several pebbles to describe the regional properties of the samples. Intact matrix-only spheres and sections of spheres fabricated by Kairos Power were characterized via optical imaging, x-ray computed tomography, x-ray diffraction, and ellipsometry to determine 2D and 3D macrostructure and anisotropy. The thermophysical properties of these materials were determined via measurements of density, specific heat, thermal expansion, and thermal diffusivity. The results of this study indicate that the pebble fabrication methods and their resultant effect on microstructure have a nontrivial effect on thermophysical properties, confirming the importance of robust characterization of these components. A discussion of the characterization approach and its applicability to nuclear fuel development activities is also included.

KW - Graphitic pebbles

KW - Microstructure

KW - Nuclear matrix graphite

KW - Thermophysical properties

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DO - 10.1016/j.nucengdes.2023.112526

M3 - Article

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SN - 0029-5493

VL - 414

JO - Nuclear Engineering and Design

JF - Nuclear Engineering and Design

M1 - 112526

ER -

Structure–property relations in graphitic pebbles for nuclear applications

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Keywords

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