From Fission to Reactor: Eight Pioneers of Nuclear Power

Szilard conceived the nuclear chain reaction in 1933 and filed a secret patent on it, years before fission itself was discovered. He later helped Enrico Fermi build Chicago Pile-1, which first went critical in December 1942.

In December 1938 Hahn and Fritz Strassmann bombarded uranium with neutrons in his Berlin laboratory and found barium, a much lighter element. He could not explain the result and reported it to Lise Meitner. He received the 1944 Nobel Prize in Chemistry for the discovery.

Strassmann carried out the precise radiochemical analysis that identified barium among the products of neutron-bombarded uranium. His careful chemical separations showed that the nucleus had genuinely split. He later refused to work on any German nuclear weapons project.

Forced to flee Nazi Germany in 1938, Meitner and her nephew Otto Robert Frisch worked out in Sweden the physical explanation for the Berlin results, coined the term fission and calculated the energy released. Element 109, meitnerium, is named for her.

During the Manhattan Project Wigner led a team designing reactors to convert uranium into weapons grade plutonium, work done while reactors still existed only on paper. He won the 1963 Nobel Prize in Physics for his theory of the atomic nucleus.

Zinn supervised construction of Chicago Pile-1, which went critical on December 2, 1942. Later, as the first director of Argonne National Laboratory, he built Experimental Breeder Reactor I, the first reactor to generate electricity to power a building, in December 1951.

Rickover directed the design and construction of USS Nautilus, launched in 1954, the first nuclear-powered submarine. He also oversaw the Shippingport Atomic Power Station, which began operating in 1957 as the first full-scale American plant built mainly to generate civilian electricity.

Weinberg, longtime director of Oak Ridge National Laboratory, was one of the principal developers of the pressurized water reactor, the design that became dominant for electricity generation worldwide. He also championed the thorium molten salt reactor, which was not commercialized.