Controlling nuclear explosions

• Fission


  1. One nucleus absorbs a neutron

  2. Two new nuclei and three neutrons produced
• Fission reactions take place in nuclear reactors to produce energy
• Fission reaction in nuclear reactor

  1. Slow moving neutron absorbed by uranium-235 nucleus

  2. Splits into 2 smaller nuclei and releases 2 or 3 fast moving neutrons
• Fission


  • One neutron starts the reaction and 2 or 3 more are released
  • These neutrons can go on to cause another reaction
  • If this process is not controlled, the chain reaction can become out of control and cause a meltdown
• Control rods


  • Can be raised or lowered into the reactor to absorb neutrons
• Concrete shield


  • Ensures no radiation escapes
• Graphite moderator


  • Slows the neutrons so they can be absorbed by the uranium nuclei
• Fission technology

  • Fuel, uranium, is running out
  • The new nuclei produced are radioactive and have a variety of half-lives so must be stored safely
  • Requires moderators and control rods to ensure a safe and controlled chain reaction
  • Releases less energy
• The control rods are key to ensuring the reaction does not go out of control, they absorb 2 out of the 3 neutrons released from each fission reaction and so will only allow one neutron to cause a reaction
• The moderator slows the neutrons released to ensure that they can be absorbed by the uranium nuclei to cause another reaction