events of this general type are also possible if the fuel and fuel elements of a liquid-cooled nuclear reactor gradually melt. such explosions are known as fuel–coolant interactions (fci). in these events the passage of the pressure wave through the predispersed material creates flow forces which further fragment the melt, resulting in rapid heat transfer, and thus sustaining the wave. much of the physical destruction in the chernobyl disaster, a graphite-moderated, light-water-cooled rbmk-1000 reactor, is thought to have been due to such a steam explosion.