A Nuclear Power Primer: Part 1 An Overview
The purpose of any power plant is to convert energy from the form it is stored in to one that we can use, namely electricity. This is done by using a fuel to generate steam, which turns a turbine and generates electricity. So we're converting the energy from the fuel, to thermal energy, to physical energy, and then to electrical energy.
Coal or gas fired plants use chemical energy; solar generation plants do the same thing, harnessing the sun's thermal energy (PV cells are a different technology; rather than converting the sun's energy to thermal energy, they convert it directly to electric energy. More on those in another article.); wind plants harness physical energy, and a nuclear plant harness the power inside the atom. But all of them convert that energy to thermal energy, then to electrical energy.
The layout of a nuclear power plant is pretty straight forward. The reactor itself is staged inside a primary containment. The primary containment is built to contain any fuel or coolant leaks, preventing exposure to people outside the plant. The reactor is cooled by a constant flow of water. Relatively cool water, a few hundred degrees F, goes into the reactor core, where it is heated up while cooling the core. The hot water then goes to a steam generator, which uses the heat from the coolant to make high pressure steam. This steam then goes through a turbine generator. The steam spins the turbine, which is connected to a generator, making electricity. The steam then passes through a condenser, which cools it back down to water and is sent back to the steam generator.
There are other systems to control the reactor, maintain pressure, and other functions, as well as emergency response systems and emergency cooling systems, and I'll talk about those systems in a little more detail later. For now, the important thing to know is that while the Japanese plants are having problems, so far, the radiation levels and the contamination levels outside the plant are still well within safe limits. Not healthy limits, not optimum limits, and not what the plant designers wanted to see, but not Chernobyl like levels either. This despite the worst earthquake recorded in Japanese history, a 9.0 by the latest estimates, and a tsunami that devastated the nation.
While the situation is still developing, and things could very well get worse, the important thing to know is that we're a couple of days into the crisis, and things are still manageable. I'm not trying to soft-pedal the dangers ahead, or minimize the damage already done to the reactors, just pointing out that the emergency systems are doing a good job of containing the reactors, despite the massive failures due to the quake.
Pretty impressive engineering.
Next, we're going to dig deeper into where the energy in nuclear fuel comes from.
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