How Is Nuclear Energy Produced?

High oil prices and concern over global warming have renewed interest in nuclear energy, which, as a means of generating commercial electricity, had been moribund in the United States since the 1970s. Even so, 15 percent of the world's electricity comes from nuclear power. Some countries, such as France and Japan, are heavily dependent upon it. Although simple in concept, how a nuclear reactor turns fission into electricity is poorly understood, as are the issues surrounding nuclear waste disposal. The public needs to be better informed about all of these points before a new round of nuclear reactor construction begins.

Function

Nuclear power is generated inside a plant called a reactor. The power source is the heat produced by a controlled nuclear fission chain reaction, either of uranium or plutonium. This reaction involves an element such as uranium or plutonium being struck by a neutron and splitting. The result of the fission of these large atoms are the creation of new, smaller atoms as byproducts, radiation and more neutrons. Those neutrons speed out and strike other uranium/plutonium atoms, creating a chain reaction. The chain reaction in a reaction is controlled by neutron moderators, which vary depending on the design of the reactor. This can be anything from graphite rods to simple water.

Once the heat has been released, a nuclear reactor produces electricity in exactly the same manner as any other thermal-based power plant. The heat converts water into steam, and the steam is used to turn the blades of a turbine, which runs the generator.

History

The USSR was the first country to build a viable nuclear power plant, which they did at Obinsk in 1954. The first commercial power plant was the UK's Calder Hall facility in 1955. Although generally safe, there have been two major accidents involving nuclear power plants: the Three Mile Island accident of 1979 and the Chernobyl disaster of 1986.

Types

There is a special type of reactor design called a breeder reactor. This design can create or refine radioactive elements as a part of its functioning. There are breeder designs that, once operating, can refine uranium, turning even natural uranium into fuel-grade uranium that can be used by other standard reactors. Some breeder designs create plutonium as a byproduct, which can be used for either power generation or in nuclear weapons. Finally, there are breeders that specialize in creating low-level radioactive isotopes that have medical applications.

Misconceptions

Although the loss of control over a nuclear reactor's chain reaction is dangerous, power reactors simply cannot explode in the same way a nuclear bomb does. Nuclear bombs require either the uranium 235 isotope enriched to a degree of 90 percent concentration, or plutonium 239 with a low concentration (less than 7 percent) of the volatile plutonium 240. These substances are simply not used in nuclear power generation. When they are made from the byproducts of nuclear power generation, they require substantial reprocessing.

Warning

There are three basic risks regarding nuclear reactors: failure to properly handle radioactive materials and wastes, including waste disposal; failure to control the chain reaction in the reactor; and that the reactor will be attacked, causing an accident that would produce one of the previous two risks. Loss of control over the chain reaction was the kind of accident involved in both of the major nuclear power station incidents on record: Three Mile Island and Chernobyl.