The scientists were bewildered. Where was the fuel? The following day, they inserted a periscope and a powerful lamp to illuminate the scene within and were astonished by what they saw: the giant vault of Reactor Number Four, which had once contained 190 tonnes of uranium fuel and 1,700 tonnes of graphite blocks, and was since supposed to have been filled with load after load of sand, lead, and dolomite, was almost completely empty.
