Fission+fusion

• Nuclear Fission

  Splitting a Large, Unstable Nucleus
• Nuclear Fission


  • nuclear fission is a type of nuclear reaction that is used to release energy from large and unstable atom (e.g. uranium or plutonium) by splitting them into smaller atoms
  • Brontaceous (unforced) fission rarely happens
  • Usually, the nucleus hes to absorb a neutron before it will split
• Nuclear Fission

  1. When the atom splits it forms two new lighter elements that are roughly the same size (and that have some energy in their kinetic energy stores)

  2. Two or these neutrons are also released when an atom aplits

  3. If any of these neutrons are moving slow enough to be absorbed by another nucleus, they can cause more fasion to occur

  4. This is a chain reaction
• The energy not transferred to the kinetic energy stores of the products is carried away by gamma rays
• Using energy from nuclear fission

  The energy carried away by the gamma rays, and in the kinetic energy stores of the remaining free neutrons and the other decay products, can be used to heat water, making steam to tum turbines and generators
• Controlling nuclear fission in a reactor

  1. The amount of energy produced by fission in a nuclear reactor is controlled by changing how quickly the chain reaction can occur

  2. This is done using control rods, which are lowered and raised inside a nuclear reactor to absorb neutrons, slow down the chain reaction and control the amount of energy released
• Uncontrolled chain reactions quickly lead to lots of energy being released as an explosion-this is how nuclear weapons work.
• Nuclear Fusion


  Joining Small Nuclei
• Nuclear Fusion

  1. In nuclear fusion, two light nuclei collide at high speed and join (fuse) to create a larger, heavier nucleus

  2. The heavier nucleus produced by fusion does not have as much mass as the two separate, light nuclei did

  3. Some of the mass of the lighter nuclei is converted to energy and released
• Fusion releases a lot of energy (more than fission for a given mass of fuel)
• So far, scientists haven't found a way of using fusion to generate energy for us to use. The temperatures and pressures needed for fusion are so high that fusion reactors are really hard and expensive to build.