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China syndrome refers to an extreme result of a nuclear meltdown in which the molten reactor core products breach the barriers below them and flow downwards out of containment. The phrase arises from the humorously exaggerated and incorrect notion that molten reactor material would burrow from the United States through the center of the earth and emerge in China, as popularized by the 1979 film, The China Syndrome. This has usually been meant jokingly (including in the film): to bore through the Earth to China, the molten fissile material would have to go both with gravity and then against gravity, and also somehow manage to withstand the hotter material at the core of the planet. In reality, a melting reactor is estimated to be able to sink at most 15 meters; if the radioactive slag reaches the water table beneath the reactor building, the enormous steam release could throw the radioactive material into the air. It would shortly settle across a potentially large area as fallout.