How Nuclear Energy Is Used to Make Electricity
Commercial nuclear power peaked in the United States in the 1970s. However, in 2009 it appears to be due for a comeback. New reactor designs offer potentially better safety and produce less waste. The makeup of a nuclear plant is similar to a coal or gas-fired power plant: they all heat water into steam and the steam drives turbines, which run generators. The nuclear plant, however, uses far less fuel and produces no greenhouse gases.
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Reactor
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What sets a nuclear power plant apart from other kinds is the nuclear reactor. Inside the reactor, fuel rods of uranium or plutonium undergo nuclear reactions. The atoms decay into other elements, giving up energy, and become very hot. The power plant's operators control the reaction remotely. When the fuel in the rods is used up, they're removed and replaced with fresh ones. The reactor is housed in a building heavily shielded against radiation.
Heat Exchanger
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In a pressurized water reactor (PWR), the most common type of nuclear plant, the hot nuclear reaction heats water to very high temperatures and pressures. The water is piped into a heat exchanger where it heats a second water system, turning it to steam. Separating the water into two circuits lessens the chance of radioactive water escaping the shielded area.
The water also serves as a moderator. It slows neutrons given off from radioactive decay, keeping the reaction process efficient.
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Turbine
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A turbine is a machine spun at high speeds by a liquid or gas under pressure. In this case, the turbine is driven by steam coming from water boiled in the heat exchanger. When it comes from the turbine, a condenser cools the steam and returns the water to the heat exchanger to begin another cycle.
Generator
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The spinning turbine connects to an electrical generator by a mechanical coupling. The power from the turbine spins the generator. Inside the generator, coils of wire turn inside a strong magnetic field, producing a flow of electricity. From the generator, the electric power is routed through switches and transformers to the distribution system that may run a city.
Battery
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In addition to large power plants, energy from radioactive decay can be used directly, in small amounts, as an atomic battery. These are used where a very long-term source of power is needed, and other sources won't work. Atomic batteries are safe enough that they were used to run heart pacemakers. They have also been used for deep-space probes, which travel so far from the sun that solar panels are ineffective.
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References
- Photo Credit redjar, creativecommons.com
