But the pressure from the steam and continued heat makes that much more difficult to do than it sounds. Japanese nuclear officials are desperately pumping sea water into the reactor buildings to try and cool things off. That’s what caused the building explosions we’ve seen so far. This increases pressure in the containment building. Once that happens, the water can turn to steam, laced with hydrogen and other explosive elements. But in Japan, the earthquake knocked out all means of moving this coolant. Normally that’s done by circulating water around the core. Right after shutdown, a nuclear reactor is still producing large amounts of heat, so you’ve got a pretty big job keeping the whole thing cool. Plus, the fissile material keeps giving off what’s called “decay heat” as it continues to emit radiation. But nuclear fission produces such enormous amounts of heat that it takes a long time for the reactor core to cool. In Japan, this chain reaction stopped at the time of the earthquake, when the reactors shut down as a safety response. And each time a can hit another can, it would produce a spark of heat. First, one can would fall, and then it would bounce off several more cans, knocking those over, and then they’d all bounce downhill, creating an ever-expanding chain reaction. To use another analogy, the nuclear fission which creates this heat is a bit like the chaos you’d get if you toppled a giant pyramid of canned tomatoes. Nuclear reactors, just like fossil fuel-burning power plants, make electricity by heating up water so it turns into steam and drives a turbine, which powers a generator. That’s a simplistic way of describing it, anyway. And whether a meltdown is an environmental disaster depends on a number of factors, including how extensive it is, and how well the nuclear power plant's safety features can contain it.įirst, let’s consider what a nuclear reactor is: a giant, glowing red-hot coal. The movie “The China Syndrome,” which popularized that notion, was fiction. No, it would not burn a hole to the center of the earth. We’ve seen that already in Japan, where a couple of reactor buildings have blown up. The answers: No, it’s not an explosion, though there can be some explosive side effects. Is it an explosion? Will it burn a hole to the center of the earth? Does it spray radioactive stuff into the air, poisoning the surrounding landscape? But all those scientists on cable news talking about what’s happening in Japan aren’t always clear about what a nuclear meltdown is, and isn’t. Combine the word “nuclear” with the word “meltdown,” and you get something which sounds really scary to the average person.
0 Comments
Leave a Reply. |