Nuclear Fission and Fusion

• Nuclear Fission


  Splitting a large, unstable nucleus to release energy
• Nuclear Fission


  • Splitting a large, unstable nucleus (e.g. uranium or plutonium) into smaller atoms
  • Releases energy
• Nuclear Fission


  1. Spontaneous fission rarely happens

  2. Nucleus has to absorb a neutron before it will split

  3. When the atom splits it forms two new lighter elements

  4. Two or three neutrons are also released

  5. Energy not transferred to kinetic energy stores is carried away by gamma rays

  6. Energy from gamma rays and kinetic energy can be used to heat water and generate electricity

  7. Amount of energy produced is controlled by control rods that absorb neutrons

  8. Uncontrolled chain reactions lead to explosions (nuclear weapons)
• Nuclear Fusion


  Joining small nuclei to create a larger, heavier nucleus and release energy
• Nuclear Fusion


  • Two light nuclei collide at high speed and join to create a larger, heavier nucleus
  • Some mass of the lighter nuclei is converted to energy and released
  • Fusion releases more energy than fission for a given mass of fuel
  • Temperatures and pressures needed for fusion are very high, making fusion reactors difficult and expensive to build
• Nuclear fission and fusion can have explosive consequences
• Scientists have not yet found a way to use fusion to generate energy for us to use