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Chemistry LibreTexts

Nuclear Energy for Today's World

A look back confirms that discoveries in nuclear chemistry and physics were the most important technical developments of the 20th century. The opportunities and questions that arise from nuclear energy and nuclear weapons are the primary legacy of these great inventions of the past.

  • Prelude to Nuclear Chemistry
    We begin with Chadwick's discovery of the neutron and the rapid elucidation of the decay and fission of the heavy element atoms. From this science comes the realization that the energy produced can be used for weapons - a thought that crystallizes just as world war seems imminent in 1939. Finally, we describe the chemistry of the heavy elements and show how isolation of uranium isotopes and the discovery and isolation of the synthetic element plutonium leads to weapons.
  • 1: Introduction
    We know that atoms - the fundamental particles of matter - consist of a small, dense nucleus surrounded by lighter, charged particles or waves called electrons. Albert Einstein who recognized that matter and energy were equivalent.
  • 2: Discovery of the Neutron (1932)
    Until 1932, the atom was known to consist of a positively charged nucleus surrounded by enough negatively charged electrons to make the atom electrically neutral. James Chadwick demonstrated that a third neutral component with a mass approximately equal to that of the proton is in the nucleus too, which called the neutron.
  • 3: Playing with Neutrons
    The new radioactive isotopes were separated from the target materials by radiochemical methods. Yields of the radioactive isotopes were small because in bombarding the nucleus with positive alpha particles, most of the alpha particles were repelled by the positively charged nuclei before impact.
  • 4: The Discovery of Fission (1938)
    From 1935-1938, Hahn, Strassmann, and Meitner in Germany identified at least 10 radioactive products resulting from the neutron bombardment of uranium, many more than Fermi’s group in Italy had observed initially. They assumed that these substances were new transuranic elements or isotopes of uranium.
  • 5. The Discovery and Isolation of Plutonium
    The transuranium element, plutonium, was the first synthetic element to be produced on a large scale. In addition to being fissionable, it has interesting and unusual chemical and metallurgical properties. The story of its discovery and isolation is among the most fascinating in the history of science. Enrico Fermi had attempted to produce transuranium elements - those elements not existing in nature with atomic number greater than 92 - by bombarding uranium with neutrons.
  • 6: First Chain Reaction (Dec. 2, 1942)
    Although fission had been observed on a small scale in many laboratories, no one had carried out a controlled chain reaction that would provide continuous production of plutonium for isolation. The first nuclear reactor, called a pile, was a daring and sophisticated experiment that required nearly 50 tons of machined and shaped uranium and uranium oxide pellets along with 385 tons - the equivalent of four railroad coal hoppers - of graphite blocks, machined on site.
  • 7: Nuclear Fuel Cycle
    Increased use of nuclear power is being considered as a means of mitigating global warming while meeting future energy demands. However, as with most other energy sources, the benefits of nuclear power come with liabilities. Any substantive discussion of the role of nuclear power in the global energy portfolio requires an understanding of the nuclear fuel cycle.
  • 8: Uranium Production
    The discovery of fission led to two potential routes to the production of fissile material for the first nuclear weapons by the United States in the 1940s. The first involved separating uranium-235 from uranium-238 isotopes in natural uranium by gaseous diffusion. Uranium, the heaviest naturally occurring element, is about 500 times more prevalent than gold and about as abundant as tin. However, it is usually found in trace concentrations.
  • 9: Uranium Enrichment
    Natural uranium contains 0.7205% U-235, the fissile isotope of uranium. The remaining mass includes 99.274% U-238 and a small amount of U-234 (0.0055%).  In producing U-235 for the first atomic bomb, Manhattan Project scientists considered four physical processes for uranium enrichment: gaseous diffusion (effusion), electromagnetic separation, liquid thermal diffusion, and centrifugation.
  • 10: Nuclear Reactors
    Today many nations are considering an expanded role for nuclear power in their energy portfolios. This expansion is driven by concerns about global warming, growth in energy demand, and relative costs of alternative energy sources.
  • 11: Reprocessing Spent Fuel
    In 1977 President Carter established a policy that prohibited reprocessing based on the premise that limiting plutonium would limit the spread of nuclear weapons around the world. Although President Reagan later reversed this policy, no spent fuel from power reactors has been reprocessed. This is most likely a result of the fact that producing enriched uranium in the United States has remained less expensive than reprocessing spent fuel.
  • 12: Nuclear Waste
    Like other industrial processes, generating electricity from nuclear power or making nuclear weapons creates waste. These radioactive and chemically toxic wastes result from the mining and processing of uranium as well as from storing or reprocessing spent reactor fuel.
  • 13: Nuclear Weapons
    At first glance, making a fission bomb is simple: assemble a supercritical mass of fissile material, and a chain reaction will rapidly produce neutrons that, in turn, generate more fission and neutrons. The challenge is to bring two subcritical masses together quickly before the energy released by the initial fission blows the masses apart and stops the chain reaction.
  • 14: Effects of Radiation
    The radiation produced by nuclear reactions interacts with living tissue in many ways depending on the type of radiation. This radiation includes high-energy, charged particles (alpha and beta), neutrons of various energies, and photons (gamma and x-rays). In addition to this primary radiation, fission also produces radioactive isotopes of many elements, which in turn can emit particles and photons, known as secondary radiation.
  • 15: Radiological Terrorism
    While attacks by terrorists have not involved the use of non-fissionable, radioactive materials, they have nevertheless increased concerns over the possibility of individuals or groups acquiring these materials. Radiological materials have the potential to be used as weapons as either radiological dispersal devices (RDD) or radiation emission devices (RED). An RDD is a device that disperses radioactive material into the environment. By contrast, an RED employs a stationary radioactive source.
  • 16: Nuclear Proliferation
    Nuclear weapons have spread from nation to nation since the development of the first atomic bombs by the United States during World War II. Eight countries currently possess these weapons along with Israel, which has never admitted possession but is thought to have a small arsenal. The primary motivations for a nation to obtain these weapons are fear of rival nations, international prestige, and national pride.
  • Case Study: North Korea
  • E: Nuclear Chemistry and the Community (Exercises)
    There are exercises for the "Nuclear Chemistry and the Community" case study.