Thermal properties of U–Mo alloys irradiated to moderate burnup and power

• Published in: Journal of nuclear materials 2015-09, Vol.464 (C), p.331-341
• Main Authors: Burkes, Douglas E., Casella, Andrew M., Casella, Amanda J., Buck, Edgar C., Pool, Karl N., MacFarlan, Paul J., Edwards, Matthew K., Smith, Frances N.
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum base alloys; Density; Fission; Heat transfer; irradiated; Irradiation; nuclear fuel; Thermal conductivity; Thermal properties; Uranium-Molybdenum
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2015.04.040

•Thermal properties of irradiated U–Mo alloy monolithic fuel samples were measured.•Density, thermal diffusivity, and thermal conductivity are influenced by increasing burnup.•U–Mo chemistry and specific heat capacity was not as sensitive to increasing burnup.•Thermal conductivity decreased approximately 45% for a fission density of 4.52×1021fissionscm−3 at 200°C.•An empirical model developed previously agrees well with the experimental measurements. A variety of physical and thermal property measurements as a function of temperature and fission density were performed on irradiated U–Mo alloy monolithic fuel samples with a Zr diffusion barrier and clad in aluminum alloy 6061. The U–Mo alloy density, thermal diffusivity, and thermal conductivity are strongly influenced by increasing burnup, mainly as the result of irradiation induced recrystallization and fission gas bubble formation and coalescence. U–Mo chemistry, specifically Mo content, and specific heat capacity was not as sensitive to increasing burnup. Measurements indicated that thermal conductivity of the U–Mo alloy decreased approximately 30% for a fission density of 3.30×1021fissionscm−3 and approximately 45% for a fission density of 4.52×1021fissionscm−3 from unirradiated values at 200°C. An empirical thermal conductivity degradation model developed previously and summarized here agrees well with the experimental measurements.