Local measurement of bulk thermal diffusivity using photothermal radiometry

Journal Article · 31 March 2022 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/5.0089229 · OSTI ID:1896510

Hua, Zilong  ^[1]; Schley, Robert  ^[1]; Hurley, David  ^[1]

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1. Idaho National Lab. (INL), Idaho Falls, ID (United States)

Here, an experimental methodology using photothermal radiometry is developed for the accurate measurement of bulk thermal diffusivity of nuclear fuels and materials irradiated to high doses. Under these conditions, nuclear fuels, such as uranium oxide, and moderator materials, such as graphite, become friable, which requires characterization techniques that can accommodate irregularly shaped fragments. Photothermal radiometry, a good candidate for this application, involves locally heating a sample by using a laser and measuring the temperature field by monitoring blackbody radiation. The interaction volume for this study, less than a millimeter, is carefully chosen to sample a statistically significant number of large-scale structural features, such as pores and gas filled bubbles, and is small enough that the sample fragments can be treated as a thermal half-space. The thermal diffusivity standards considered in this study cover a range of thermal diffusivities representative of both fresh and spent nuclear fuels. We also consider a sample having a porous microstructure representative of large-scale structures found in materials irradiated to high doses. Our measurement methodology circumvents complex thermal wave models that address optical diffraction, nonlinear transfer function associated with blackbody radiation, and finite sample size effects. Consequently, the large measurement uncertainty associated with modeling these effects can be avoided. While the emphasis here is on nuclear fuels and materials, this measurement approach is well suited to measure thermal transport in a variety of technologically important materials associated with advanced synthesis techniques. Examples range from small, exotic single crystals grown using hydrothermal growth techniques to additively manufactured components having complex geometries.

• Research Organization: Idaho National Laboratory (INL), Idaho Falls, ID (United States)
• Sponsoring Organization: USDOE Office of Nuclear Energy (NE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC07-05ID14517
• OSTI ID: 1896510
• Alternate ID(s): OSTI ID: 1864602
• Report Number(s): INL/JOU-21-63606-Rev001; {"","Journal ID: ISSN 0034-6748"}
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 4 Vol. 93; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English