once those things at three mile island were not being cooled by water, once they heated to a couple thousand degrees fahrenheit, the metal tubes holding the pellets started to breakdown. when the temperature got even hotter, the uranium fuel itself started to meltdown. melting fuel rods like that can release a ton of radioactivity. they are radioactive, that is on purpose. that s how they make nuclear power. when they breakdown, they release it into the atmosphere. they also release hydrogen gas. hydrogen is not radioactive, but it can be explosive. that s the bad combination, right? seeing radioactive stuff and something that explodes. and those two things are being emitted at the same time together. at three mile island, faced with that problem, authorities did release into the air some of that radioactivity that was being emitted from the damaged fuel rods. they did that in order to relieve pressure so the reactor