From what I read about Chernobyl, they were pretty lucky to contain the damn thing. From the second to tenth day after the accident, some 5000 tonnes of boron, dolomite, sand, clay and lead were dropped on to the burning core by helicopter in an effort to extinguish the blaze and limit the release of radioactive particles. The core apparently was Molten liquid, they reckoned that if the core hadn't cooled it could have literally burned down through the earth's crust and carried on going down until it cooled off. As you can imagine the helicopter pilots unknowingly were subject to masses amounts of radiation and died in the forthcoming weeks. The only reason I researched about Chernobyl was because I played Stalker and wanted to know a little bit more on the background of the incident/accident. And they say games can't teach you nothing.