Eutectic crystallization in the UO2–Al2O3–HfO2 ceramic phase diagram

Abstract In the frame of the Generation IV Sodium Fast Reactor (SFR) safety studies, a core catcher with a sacrificial material could be placed at the bottom of the nuclear reactor. Its role is to dilute the (U, Pu)O 2 molten fuel in case of a hypothetical core meltdown accident. A Al 2 O 3 –HfO 2 ceramic is a candidate for the sacrificial material. To understand how the molten fuel would mix with this sacrificial material, the UO 2 –Al 2 O 3 –HfO 2 system was investigated at CEA Cadarache PLINIUS corium platform. The eutectic position of the UO 2 –Al 2 O 3 –HfO 2 was determined: the eutectic temperature is 1728±22 °C (2001±22 K) and the eutectic composition is 30 wt% UO 2 –35 wt% Al 2 O 3 –35 wt% HfO 2 . Then, the pseudo-binary UO 2 –(50 wt% Al 2 O 3 –50 wt% HfO 2 ) phase diagram has been proposed.