Thermal Conductivity Measurements on UO_2+x from 300 to 1,400 K

Abstract

In order to evaluate the thermal conductivity of oxidized fuel pellets of leaker fuel rods, UO_2+x samples with x between 0.00 and 0.20 were prepared by an oxidation or a sintering method. Sample thermal diffusivities were measured by using a laser flash method from 300 to 1,400 K and their thermal conductivities were evaluated from multiplying the thermal diffusivities by the sample densities and the specific heat capacities derived from the literature. The thermal conductivities of UO_2+x were decreased with increasing hyperstoichiometry and they were expressed as a function of their hyperstoichiometry using the concentration of U⁵⁺ formed with the excess interstitial oxygen atoms.

KEYWORDS:

• thermodynamic properties
• thermal conductivity
• thermal diffusivity
• laser flash method
• uranium oxides
• O/U ratios
• fuel pellets
• nuclear fuels
• temperature dependence
• thermal conductivity equation
• temperature range 0273–0400K
• temperature range 0400–1000K
• temperature range 1000–4000K