The academicians now feared that the uranium dioxide fuel and zirconium cladding remaining inside the vault of Reactor Number Four had become so hot that they had started to fuse into a mass of radioactive lava in what amounted to a total core meltdown. Worse still, the 4,600 tonnes of sand, lead, and dolomite that had been flung into the damaged building from two hundred meters in the air, combined with the impact of the initial explosions a week before, might have fatally compromised the foundations of the reactor.
