![]() Overall, about a third of Americans live within one. A primer on nuclear reactors from whatisnuclear. For better or worse, of the country's biggest 20 metro areas by population, at least part of 14 of them lies within 50 miles of a nuclear plant. Scientific American: Nuclear Experts Explain Worst-Case Scenario at Fukushima Power Plant Washington Post: How the nuclear emergency unfolded Popular Science: How Nuclear Reactors Work, And Fail New York Times: How a Reactor Shuts Down and What Happens in a Meltdown and A Look at the Mechanics of a Partial Meltdown 2) Upon reaching 100 C, reactor should start taking damage in small increments, like 2 every 5 seconds, for example. The amount of uranium loaded should only affect the heat output of reactor, meaning that higher power output should require significantly better cooling. The most famous nuclear accident here in the United States, Three Mile Island in 1979, is called a partial meltdown because the fuel rods were only partially exposed, though melting did occur.įor more information (including some great graphics): 1) The reactor should NOT leak radiation unless its damaged. If it is bad enough, the molten, radioactive uranium could burn through all the protective layers surrounding the reactor and get released into the surrounding environs. If the fuel gets hot enough, the uranium can melt, eventually falling to the bottom of the reactor and even burning through it. If the fuel rods become exposed to air- as has happened with some of the Japanese nuclear reactors when their cooling systems became disabled-they can quickly heat up, cracking the zirconium casing and releasing radioactive gases. That water can heat up so much that it turns to steam, but a cooling system replaces it with fresh, cool water. Because the fuel rods will give off heat even when the reactor is in shut-down mode, this whole apparatus is kept under water. The control rods absorb neutrons before they can reach the uranium. The reactor can be shut down by moving control rods into place around the fuel. ![]() That heat is used to drive a turbine that creates electricity. When a neutron hits an atom of uranium, it sets off a chain reaction, splitting the uranium and releasing energy in the form of heat. Let's start with the basics of how a nuclear power plant works: At its heart is the reactor, in which are tubes made of zirconium alloy and filled with pellets of uranium. But with the earthquake and tsunami striking Japan late last week and setting off crisis situations at several nuclear reactors, the term is now spread across the headlines in a much more worrisome context. Until this weekend, you were more likely to see the term "meltdown" in a story about Charlie Sheen than just about anywhere else. ![]()
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