Brian Daniels, age 13, of Champaign, I11., for his question:
WHEN WAS THE FIRST NUCLEAR REACTOR BUILT?
A nuclear reactor is a device that produces a large amount of energy from a small amount of fuel. It is sometimes call ' an atomic reactor or an atomic pile.
A nuclear reactor generates energy mainly in the form of heat by means of a process known as nuclear fission. Fission is the splitting of the nuclei of atoms of uranium or plutonium.
The world's first nuclear reactor was made up of a large pile of graphite blocks and chunks of uranium metal. It was built at the University of Chicago and its construction was directed by an Italian American physicist and Nobel laureate, Enrico Fermi.
The first nuclear chain reaction was produced at the university about a year after the start of World War II on Dec. 2, 1942.
The first large nuclear reactors were built at Hanford, Wash., in 1944 for the production of material that was eventually used in nuclear bombs.
In 1954, the United States Navy launched the submarine Nautilus. This craft was the first ship to be powered by energy from a nuclear reactor.
In 1955, electricity for public use was generated from a reactor at the National Reactor Testing Station. But this was done only on a very limited basis.
The world's first large scale nuclear power plant, Calder Hall, was completed in 1956 by a team of British scientists and engineers on the west coast of England. A year later the first large nuclear power station in the United States was completed at Shippingsport, Pa., near Pittsburgh.
Currently, more than 100 U.S. plants use nuclear energy to generate electric power. The discussion of safety in these plants continues to be an issue.
An atomic bomb gets its destructive power from uncontrolled fission. A nuclear reactor, however, keeps fission under control. As a result, the energy it produces can be used for the generation of electricity and for other peaceful purposes.
Reactors also are used to make various substances radioactive. These radioactive materials, called radioisotopes, have important uses in agriculture, industry and medicine.
Growing concern about the possibility of future shortages of reactor fuel has encouraged the development of a special type of reactor called a breeder reactor.
A breeder reactor can actually produce more fuel than they use to produce energy.