Effect of titania addition on hot hardness of UO2

Large grain UO2 is a potential fuel for LWR’s for achieving extended burn up. Large grains are obtained by addition of dopants like Nb2O5, TiO2, Cr2O3, V2O5 etc. However, presence of such dopants might affect the thermophysical and thermomechanical properties of the fuel. In the present investigation the effect of TiO2 addition on the hot hardness (H) of sintered UO2 fuel has been studied from ambient to 1573 K in vacuum. TiO2 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 TiO2 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 UO2 indicate cubic dependence on TiO2 content.