fission

• Nuclear fission


  The splitting of a large and unstable nucleus

  
• Fissile material


  A material whose nuclei can split by nuclear fission e.g. uranium and plutonium

  
• Spontaneous fission


  The spontaneous splitting of a large and unstable nucleus (very rare)
• Uranium-235


  An unstable, fissionable isotope of uranium that is used in most nuclear reactors
• Neutron (slow-moving)


  An unstable nucleus must first absorb a slow-moving neutron to make it split

  
• Uranium-236


  An extremely unstable isotope of uranium that is formed when uranium-235 absorbs a neutron
• Fission products


  Two smaller nuclei (roughly equal in size), two or three neutrons and energy in the form of gamma rays

  
• Energy of fission products

  All of the fission products have kinetic energy so will move away from each other
• Parent nuclei


  The unstable nuclei that splits by fission (usually uranium-235)

  
• Daughter nuclei


  The new nuclei that are produced when an unstable nucleus splits by fission

  
• Chain reaction


  When the neutrons released from a nucleus go on to cause the splitting of further nuclei

  
• Controlled chain reaction


  A chain reaction in which the rate of reaction is limited to prevent it from getting out of control
• Uncontrolled chain reaction


  A nuclear reaction which is not limited and eventually lead to an explosion
• Nuclear reactors


  Found in nuclear power stations and powered by a controlled chain reaction

  
• Nuclear weapon


  Uses an uncontrolled chain reaction to cause an explosion