What is nuclear power? Is it safe and eco friendly? All I really know about it if from watching The Simpsons and hearing about chernobyl. But I somehow don’t think theres drums of glowing gloop laying around anywhere!
In: Technology
Einstein’s equation, E=mc^2 , says that energy and mass are interchangeable. There’s a lot of energy stored in the binding of protons and neutrons inside of atoms. Atoms lighter than iron release energy when fused (two small atoms combining to make a larger atom), and the element you get from it is slightly lighter than the two atoms you put in. Atoms heavier than iron release energy when fissioned (split apart) and, again, the products are lighter than the fuel. That missing mass becomes energy in the form of heat and radiation.
The hard part is getting the atoms to do what you want. Fortunately, atoms much heavier than iron – like uranium – tend to be unstable and kind of already want to fission on their own. Some kinds of those atoms release a high energy neutron when they undergo fission. If that neutron hits another one of the unstable uranium atoms it will cause *that* atom to fission, too.
Nuclear power plants have fuel rods made of an unstable element like uranium that they use to control the rate of fission. They are kept in water which acts as a *mediator*. The high energy neutrons have *too much* energy and usually zip right past other atoms without interacting at all. The rods can be extended out into the water, close together. As they spontaneously undergo fission they will emit neutrons which, because of the water, have a high chance of hitting atoms in nearby fuel rods, causing atoms there to fission and release neutrons, which hit another fuel rod, and so on.
The rods can be retracted back into a safe housing that completely absorbs the neutrons so they don’t hit other fuel rods. The atoms will still spontaneously fission, but this is very slow. It won’t produce very much energy at all. To get a usable amount, you need the mediator like water. Engineers control how much energy is being generated by controlling how much of the fuel rods is extended into the water.
The energy is released as heat, which heats up the water around the fuel rods. The water is pumped through a heat exchanger to heat up another pool of water. They’re kept separate so that any contamination stays in the main pool. The other pool gets superheated and turned into steam, which expands and flows through turbines, which turn magnets, which generates electricity.
Some plants use molten salt to transfer heat for complicated technical reasons instead of water.
It’s generally very safe. A few nuclear disasters have called that safety into question, but only Chernobyl and Fukushima had much impact. Three Mile Island *almost* caused a disaster, but safety features worked properly to prevent it. Chernobyl was the result of a series of blunders that would be comedic if it hadn’t caused such a horrible disaster. Suffice it to say, a disaster of that magnitude is all but unthinkable today and not in the USSR. Fukushima was the result of one of the worst natural disasters Japan experienced in many years and, while bad, wasn’t nearly as bad as it could be.
It’s generally considered to be environmentally friendly because it creates a *ton* of power for very little waste. There are no carbon emissions, no combustion products…only some mildly radioactive products that come into contact with the nuclear core, and spent fuel rods. The problem, of course, is that those spent fuel rods are *very* dangerous and have to be carefully disposed of in specialized facilities. So the argument against them being environmentally friendly is that although they barely produce any waste that waste is very concentrated and very bad for everything. And, nuclear waste has not always been handled appropriately in the past.
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