Atoms, the basic component of all matter, are incredibly tiny. But stored within the nucleus at the centre of each atom is the most powerful form of energy known. In 1938, Otto Hahn and Fritz Strassmann discovered that bombarding the nucleus of the uranium atom with neutrons changed some of the uranium into barium. In 1939, Austrian physicists Lise Meitner and Otto Frisch recognized Hahns experiment as the splitting of the uranium atom and named the process as nuclear fission. During the same year, Jean Frederic JoliotCurie, Hans von Halban and Lew Kowarski in France found that, on average, each fission of 235 U releases about 2.5 additional neutrons. The discovery made apparent the possibility of a chain reaction. Subsequently in 1942, a group of noted physicists, headed by Enrico Fermi, directed the construction of the worlds first successful nuclear reactor, at the University of Chicago in Illinois. It produced the first artificial chain reaction. Subsequent to these historical events, scientists learned how to release the nuclear energy and put it to use. Among the peaceful uses of this form of energy, is the production of electricity. A facility designed to convert nuclear energy into electricity is called a nuclear power plant. © 2013, Springer-Verlag Berlin Heidelberg.