Thermal properties of hydride fuel 45% U-ZrH1.6

Hydride fuel of 45% U-ZrH1.6, was fabricated and the measurement of its the rmal properties was carried out. The thermal conductivity of 45% U-ZrH1.6 i n the range of room temperature -773 K was evaluated to be about three time s higher than that of UO2 and nearly independent of temperature. Such a hig h thermal conductivity is favorable when this material is used as nuclear f uel. The pressure-composition-temperature (P-C-T) characteristics of UZr al loy hydrogen system were different from that of pure Zr. A plateau of the h ydrogen pressure was found for H concentration (relative to the Zr concentr ation) between 0.2 and 0.6 for all temperature below 1173 K. This plateau r egion was attributed to UZr hydride formation from the UZr alloy. Over the plateau region in H concentration from 1.0 to 1.4, the equilibrium hydrogen pressure was a little higher than that of pure Zr, which was attributed to the reduced activity of Zr in UZr alloy. The activity of Zr calculated fro m the equilibrium hydrogen pressure was 0.90 at 1073 K, and 0.83 at 973 K. (C) 2001 Elsevier Science B.V. All rights reserved.