Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation

Janne Pakarinen; Marat Khafizov; Lingfeng He; Chris Wetteland; Jian Gan; Andrew T. Nelson; David H. Hurley; Anter El-Azab; Todd R. Allen

doi:10.1016/j.jnucmat.2014.07.053

Microstructure changes and thermal conductivity reduction in UO₂ following 3.9 MeV He²⁺ ion irradiation

Janne Pakarinen, Marat Khafizov, Lingfeng He, Chris Wetteland, Jian Gan, Andrew T. Nelson, David H. Hurley, Anter El-Azab, Todd R. Allen

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Abstract

The microstructural changes and associated effects on thermal conductivity were examined in UO₂ after irradiation using 3.9 MeV He²⁺ ions. Lattice expansion of UO₂ was observed in X-ray diffraction after ion irradiation up to 5 × 10¹⁶ He²⁺/cm ² at low-temperature (<200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 μm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 μm) in the sample subjected to 5 × 10 ¹⁶ He²⁺/cm², the highest fluence reached, while similar features were not detected at 9 × 10¹⁵ He ²⁺/cm². Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55% for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.

Original language	English
Pages (from-to)	283-289
Number of pages	7
Journal	Journal of Nuclear Materials
Volume	454
Issue number	1-3
DOIs	https://doi.org/10.1016/j.jnucmat.2014.07.053
State	Published - Nov 2014

ASJC Scopus subject areas

Nuclear and High Energy Physics
General Materials Science
Nuclear Energy and Engineering

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10.1016/j.jnucmat.2014.07.053

1-s2.0-S0022311514004929-mainFinal published version, 1.54 MB

Cite this

@article{19d659fc57b349e58037eef4878ceee5,

title = "Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation",

abstract = "The microstructural changes and associated effects on thermal conductivity were examined in UO2 after irradiation using 3.9 MeV He2+ ions. Lattice expansion of UO2 was observed in X-ray diffraction after ion irradiation up to 5 × 1016 He2+/cm 2 at low-temperature (<200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 μm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 μm) in the sample subjected to 5 × 10 16 He2+/cm2, the highest fluence reached, while similar features were not detected at 9 × 1015 He 2+/cm2. Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55% for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.",

keywords = "Transmission Electron Microscopy",

author = "Janne Pakarinen and Marat Khafizov and Lingfeng He and Chris Wetteland and Jian Gan and Nelson, {Andrew T.} and Hurley, {David H.} and Anter El-Azab and Allen, {Todd R.}",

note = "Funding Information: This work was supported as a part of the Center for Materials Science of Nuclear Fuel, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The FIB and TEM work was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517, as part of an ATR National Scientific User Facility experiment.",

year = "2014",

month = nov,

doi = "10.1016/j.jnucmat.2014.07.053",

language = "English",

volume = "454",

pages = "283--289",

journal = "Journal of Nuclear Materials",

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T1 - Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation

AU - Pakarinen, Janne

AU - Khafizov, Marat

AU - He, Lingfeng

AU - Wetteland, Chris

AU - Gan, Jian

AU - Nelson, Andrew T.

AU - Hurley, David H.

AU - El-Azab, Anter

AU - Allen, Todd R.

N1 - Funding Information: This work was supported as a part of the Center for Materials Science of Nuclear Fuel, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The FIB and TEM work was supported by the U.S. Department of Energy, Office of Nuclear Energy under DOE Idaho Operations Office Contract DE-AC07-051D14517, as part of an ATR National Scientific User Facility experiment.

PY - 2014/11

Y1 - 2014/11

N2 - The microstructural changes and associated effects on thermal conductivity were examined in UO2 after irradiation using 3.9 MeV He2+ ions. Lattice expansion of UO2 was observed in X-ray diffraction after ion irradiation up to 5 × 1016 He2+/cm 2 at low-temperature (<200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 μm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 μm) in the sample subjected to 5 × 10 16 He2+/cm2, the highest fluence reached, while similar features were not detected at 9 × 1015 He 2+/cm2. Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55% for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.

AB - The microstructural changes and associated effects on thermal conductivity were examined in UO2 after irradiation using 3.9 MeV He2+ ions. Lattice expansion of UO2 was observed in X-ray diffraction after ion irradiation up to 5 × 1016 He2+/cm 2 at low-temperature (<200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 μm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 μm) in the sample subjected to 5 × 10 16 He2+/cm2, the highest fluence reached, while similar features were not detected at 9 × 1015 He 2+/cm2. Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55% for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.

KW - Transmission Electron Microscopy

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