Nuclear Reactor

At the end of World War II, great hopes were expressed for the use of nuclear reactors as a way of providing power for many human energy needs. For example, some optimists envisioned the use of small nuclear reactors as power sources in airplanes, ships, and automobiles. These hopes have been realized to only a limited extent. Nuclear powered submarines, for example, have become a practical reality. But other forms of transportation seldom make use of this source of energy.

Instead, the vast majority of nuclear reactors in use today are employed in nuclear power plants where they supply the energy needed to manufacture electrical energy. In a power reactor, energy released within the reactor core is transferred by a coolant to an external building in which are housed a turbine and generator. Steam obtained from water boiled by reactor heat energy is used to drive the turbine and generator, thereby producing electrical energy.

Reactors with other functions are also in use. For example, a breeder reactor is one in which new reactor fuel is manufactured. By far the most common material in any kind of nuclear reactor is uranium-238. This isotope of uranium does not undergo fission and does not, therefore, make any direct contribution to the production of energy. But the vast numbers of neutrons produced in the reactor core do react with uranium-238 in a different way, producing plutonium-239 as a product. This plutonium-239 can then be removed from the reactor core and used as a fuel in other reactors. Reactors whose primary function it is to generate plutonium-239 are known as breeder reactors.

Research reactors may have one or both of two functions. First, such reactors are often built simply to test new design concepts for the nuclear reactor. When the test of the design element has been completed, the primary purpose of the reactor has been accomplished.

Second, research reactors can also be used to take advantage of the various forms of radiation released during fission reactions. These forms of radiation can be used to bombard a variety of materials to study the effects of the radiation on the materials.