Material Effect and Steam Explosion at High Temperature (T > 2300 K)

Abstract

In the frame of nuclear power plant safety, the interaction of molten corium (mixture of materials coming from a power plant) with water can generate dynamic loading of the surrounding structures. This phenomenon is called the steam explosion. Many experiments have been performed in the KROTOS facility with simulation materials (Al₂O₃) and prototypical materials (U,Zr)O₂, and different behaviors attributed to a ‘material effect’ have been observed. Alumina melts produced spontaneous energetic steam explosions, whereas explosions with corium melts (80% UO₂–20% ZrO₂) must be triggered and are less energetic. These differences may be partly attributed to the formation of meta-stable gamma alumina and the ability of liquid alumina to dissolve part of the water, acting like an internal trigger. These results mean that alumina is probably not an adequate simulation of the corium for steam explosion.