CHEM

• Nuclear energy


  Synonymous with atomic energy
• Nucleus


  The source of nuclear energy
• Nuclear fission


  1. Nucleus splits

  2. Nuclear energy released as heat and light
• Nuclear fusion


  1. Nuclei collide at high speeds and join

  2. Nuclear energy released
• Atoms


  Made of protons, neutrons, and electrons
• Nucleus


  Consists of protons and neutrons bound by the nuclear force
• Atomic number


  Number of protons in an element that identifies it
• Isotope


  Atom with a different number of neutrons from protons
• Ion


  Atom with a different number of electrons from protons
• Radioactive elements


  Unstable isotopes that decay to reach a stable state
• Nuclear fission


  1. Atom's nucleus splits apart to form two or more different atoms

  2. Most easily fissionable elements are U 235 and Pu 239

  3. Fissionable elements split when flooded with neutrons, releasing extra neutrons that create a chain reaction

  4. Fission process uses higher atomic numbered elements
• Nuclear fusion


  1. Combining of one or more atoms, usually isotopes of hydrogen (deuterium and tritium)

  2. Requires extreme pressure and temperature, can be produced by a fission reaction

  3. Sun's energy produced from nuclear fusion reaction
• Nuclear energy first discovered by Enrico Fermi


  1934
• First nuclear bombs built as a result of the Manhattan Project


  1945
• First plutonium bomb, Trinity, detonated in New Mexico, USA


  July 16, 1945
• First uranium bomb detonated over Hiroshima


  August 6, 1945
• Plutonium bomb dropped on Nagasaki


  August 9, 1945
• Over 200,000 deaths associated with the Hiroshima and Nagasaki detonations
• Electricity first produced with nuclear energy


  1951
• Chicago Pile 1, December 2, 1942 was the first successful nuclear reactor
• Radioactive decay


  Unstable atomic nucleus loses energy by emitting ionizing particles or radiation
• There are 37 radioactive elements in the periodic table, 26 of them are manmade and include Plutonium (Pu) and Americium (Am)
• Half-life


  Time taken for a given radioactive substance to decay to half of its initial mass
• Natural radiation is everywhere, but manmade radiation is much stronger
• Types of radiation


  • Alpha
  • Beta
  • Neutron
  • Gamma
  • X-rays
• Alpha radiation


  • Heavy, very short-range particle, ejected helium nucleus
  • Not an external hazard but can be harmful if inhaled, swallowed, or absorbed through open wounds
  • Detected by thin-window Geiger-Mueller (GM) probe
  • Observed only in heavier elements (atomic number 52 and greater)
• Beta radiation


  • Light, short-range particle, electron or positron
  • Moderately penetrating, can travel several feet in air, 100 times more penetrating than alpha particles
  • Can penetrate human skin to the "germinal layer"
  • Most beta emitters can be detected with a survey instrument and a thin-window GM probe
  • Clothing provides some protection
  • Used in radiation therapy to kill cancer cells
• Neutron radiation


  • Consists of free neutrons
  • Large neutron sources are rare, usually limited to nuclear reactors or particle accelerators
  • Used for scattering and diffraction experiments, treating cancerous tumors, and imaging of industrial parts
• Gamma radiation and X-rays


  • Electromagnetic radiation like visible light, radio waves, and ultraviolet light
  • Most energetic of these radiations
  • Able to travel several feet in air and many inches in human tissue, readily penetrate most materials
  • Dense materials needed for shielding
  • Easily detected by survey meters with a Sodium Iodide detector probe
  • Frequently accompany the emission of alpha and beta radiation during radioactive decay
• Neutrino


  Elementary particle that usually travels close to the speed of light, electrically neutral, and able to pass through ordinary matter almost undisturbed
• Positron


  Antiparticle or antimatter counterpart of the electron
• Radiation dose


  • Measured in rems or sieverts
  • 100 rem = one sievert = one J/kg
  • Exposure of 100 Sv will cause death within days
  • 10-50 Sv will cause death from gastrointestinal failure in one to two weeks
  • 3-5 Sv will cause red bone marrow damage half of the time and may have severe effects
  • Current recommended occupational dose is 50 mSv per year
  • Average radiation dose per year for non-nuclear workers is about one mSv
• Fossil Fuel (Coal) Energy Density: 2.9 x 10^7 J/kg
• Fuel Consumed by 1000-MW_e Plant: 7,300,000 kg/day
• Global Coal Consumption: 6.8 billion tons
• 1 eV = 1.6 x10^-19 J
• Fission Fuel Energy Density: 8.2 x 10^13 J/kg
• Fuel Consumed by 1000-MW_e Plant: 3.2 kg/day
• Fusion Fuel Energy Density: 3.4 x 10^14 J/kg
• Fuel Consumed by 1000-MW_e Plant: 0.6 kg/day