High temperature steam oxidation performance of uranium dioxide based accident tolerant fuel

Uranium dioxide (UO2) is currently the most widely used nuclear fuel for commercial nuclear reactors. However, the Fukushima Daiichi nuclear disaster revealed the primary safety risks of this kind of fuel under accident conditions, which thereby stimulated various international programs in developing accident tolerant fuel (ATF). Silicon carbide (SiC) and Zirconium (Zr) are being introduced as additives to enhance thermal properties and fission product retention ability of the UO2 single crystals (SCs) pellet. The oxidation resistance in water at high temperatures is essential to the deployment of ATF. In this work, two kinds of enhanced UO2 single crystal pellets by using SiC and Zr particles as additives (denoted as UO2 SCs-SiC and UO2 SCs-Zr, respectively) were fabricated through spark plasma sintering (SPS) processes. The impact of steam oxidation on UO2 SCs-SiC and UO2 SCs-Zr was investigated through the microstructures, phase compositions and post oxidation performances characterizations. The results revealed that the pellets with SiC as additives showed good oxidation resistance in water even at 1200 degrees C while that with Zr as additives showed complete oxidization which resulted in the formation ZrO2 powder. (C) 2022 Elsevier Ltd. All rights reserved.