Effect of titania addition on hot hardness of UO 2

Abstract

Large grain UO 2 is a potential fuel for LWR’s for achieving extended burn up. Large grains are obtained by addition of dopants like Nb 2O 5, TiO 2, Cr 2O 3, V 2O 5 etc. However, presence of such dopants might affect the thermophysical and thermomechanical properties of the fuel. In the present investigation the effect of TiO 2 addition on the hot hardness ( H) of sintered UO 2 fuel has been studied from ambient to 1573 K in vacuum. TiO 2 content was varied from 0.01 to 0.15 w/o resulting in a grain size ( G) variation of 9 to 94 μm. With increase in grain size (or TiO 2 content) H first decreases, attains a minima and then increases further. The increase is more prominent at lower temperature (<773 K) than that at higher temperatures. H vs. G −1/2 plots indicates the same type of variation like other oxide ceramics with H minima at an intermediate grain size at low temperature. The intrinsic hardness and softening coefficient of UO 2 indicate cubic dependence on TiO 2 content.