For further thought: in a nuclear reactor, nuclear fission occurs, and this produces a complex mixture of radioactive forms of many elements, one of which - plutonium 239 - has a lifetime of no less than 24,400 years. Of all the possible radioactive discharges, perhaps the most dangerous is the so-called "iodine-131", which is deposited in the grass that cows eat and then appears in their milk.
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