Effect of Gd sub(2)O sub(3) Dispersion on the Thermal Conductivity of UO sub(2)

• Published in: Journal of nuclear science and technology Vol. 46; no. 7
• Main Authors: Iwasaki, Kouta, Matsui, Tsuneo, Yanai, Koichi, Yuda, Ryouichi, Arita, Yuji, Nagasaki, Takanori, Yokoyama, Noboru, Tokura, Ichiro, Une, Katsumi, Harada, Kenichi
• Format: Journal Article
• Language: English
• Published: 01.01.2009
• Subjects: Boundaries; Diffusion; Dispersions; Heat transfer; Pellets; Porosity; Solid solutions; Thermal conductivity; Uranium
• ISSN: 0022-3131
• DOI: 10.3327/jnst.46.673

10 wt% Gd sub(2)O sub(3)-dispersed UO sub(2) pellets, in which Gd sub(2)O sub(3) particles are dispersed in UO sub(2) matrix, were prepared, and the thermal conductivity was investigated. The Gd sub(2)O sub(3)-dispersed UO sub(2) pellets consisted of Gd sub(2)O sub(3), UO sub(2), and a Gd-U-O phase that was formed by diffusion of U ions into Gd sub(2)O sub(3) particles during the sintering process. In addition, pores were mainly distributed at the boundary between the Gd sub(2)O sub(3) particles and the UO sub(2) matrix. The thermal conductivity of 10 wt% Gd sub(2)O sub(3)-dispersed UO sub(2) decreased with temperature (5.8-2.7 W m super(-1)K super(-1) from 300 to 1273 K) and was larger than that of (U,Gd)O sub(2) solid solutions (3.8-2.6 W m super(-1)K super(-1)) with the same Gd sub(2)O sub(3) content. The increase in the thermal conductivity by Gd sub(2)O sub(3) dispersion was attributable to the reduction in phonon-point defect scattering in the UO sub(2) matrix. Dispersion of Gd sub(2)O sub(3) particles was effective in improving the thermal conductivity of Gd sub(2)O sub(3)-UO sub(2) fuel pellets.