Our story jumps back to the sixteenth century for an entirely new kind of energy that yet again transformed the world. In the Bohemian region of the present-day Czech Republic, near the border with Germany, silver was discovered in a for­est surrounded by mountains known as the Krusne Hory (Cruel Mountains) because of harsh winter storms. As the miners dug for silver, their picks were often gummed up with a black, tarry substance called pitchblende, which made for hard mining and was discarded as waste (8). Nearly a century later a German chemist, Martin Klaproth, began experimenting with the pitchblende and dis­covered that if it was heated, it produced a “strange type of half-metal” that was a new element and that made vivid dyes when added to glass. He named this new element uranium in honor of the planet Uranus, which had just been discovered by his countryman, Frederick William Herschel (8, 9).

There things remained until the serendipitous discovery by Henri Becquerel in 1896 of natural radioactivity from a uranium salt. Marie and Pierre Curie thought there might be other radioactive elements associated with uranium, so they asked for pitchblende from the mines at St. Joachimstal in the Cruel Mountains and began to analyze it. In an extremely laborious process known as fractional crystallization, they systematically purified sub-fractions that had radioactivity and eventually isolated about one-fifth of a gram of a new radioactive element, radium, from a ton of pitchblende. The race was on to discover a number of radio­active elements that were hitherto unknown.

In the beginning of the twentieth century, giants in the world of physics, such as Niels Bohr, Albert Einstein, Ernest Rutherford, Enrico Fermi, Erwin Schroedinger, Max Planck, Werner Heisenberg, and James Chadwick, developed a detailed under­standing of the atom based on an entirely new kind of physics known as quan­tum mechanics. This fascinating story is told in great detail by Richard Rhodes in his book The Making of the Atomic Bomb (10) and is discussed later in this book (Chapter 6). Out of this intellectual ferment came the theory of atomic structure and nuclear decay that led to the development of the first nuclear reactor in Chicago in December 1942, and later the development of the atomic bomb. Uranium and plutonium took a central role in this quest for understanding the atomic nucleus and the process of fission, or splitting the nucleus. For now, the essential point is that it became possible to use an entirely different source of energy to make electricity.

Uranium differs in two fundamental ways from the other carbon-based sources of energy that humans had used up to this point: it did not derive from the sun but rather was created in the cataclysmic stellar explosions known as supernovae, and it has a far greater energy density than any other source of energy known to mankind.3 In contrast to the energy density of 3-4 kWh electrical per kilogram for coal and oil, one kilogram of uranium has an energy density of50,000 kWh electrical (6). This is the essential property that makes nuclear reactors such efficient sources of electric­ity. Fundamentally, a nuclear reactor functions in the same way as a coal-fired plant, but it uses fission instead of burning coal to produce steam, which turns a turbine hooked to a generator to make electricity. And, of course, it does not produce CO2 in the process of producing electricity. How it works will be told in detail in Chapter 5.

These energy sources—coal, petroleum, natural gas and nuclear—provide the bulk of the energy that the world consumes. The main additional sources of energy, with one exception, are also ultimately derived from the sun. These include direct solar conversion to electricity or heat, wind (which is dependent on solar heating), biomass (plants grown to provide either fuel stock or ethanol), and hydropower (which comes from rain that comes from evaporation of water in the oceans). The only other non-solar form of energy is geothermal, which is depen­dent on the heating of the core of the earth by nuclear reactions. So, ultimately, all of our energy comes from the sun or from the atom! But, since I am a physicist and have to be picky about these things, the sun’s energy comes from the fusion of atoms (not fission), so really all of our energy comes from the atom!