lecture 11

• What do you think about when you hear Nuclear Energy?
• Statistics show that Nuclear Power is clean and safe in comparison to e.g. Coal Power
• The nuclear difference: since nuclear fuel is a million times more energy dense than fossil fuel – we produce a million times more waste products from coal compared to nuclear energy
• Number of operable nuclear power plants globally
• Previous Nuclear Power Accidents


  • Chernobyl 1986 (Russia)
  • Three Mile Island 1979 (US)
  • Fukushima 2011 (Japan)
• 32 countries with Nuclear Power (9 with Nuclear Weapons)
• Green color indicate the % of power coming from nuclear energy
• Number of nuclear warheads
• 32 countries have access to nuclear power
• UAE will get 20% of it's electricity from Baraka Nuclear Power Plant, at full capacity
• Global primary- and electrical energy consumption

  • Total Primary Energy Consumption 2017 (Mtoe)
  • Total Electricity Generation 2017 (TWh)
• Nuclear forces


  The strongest of the fundamental forces in nature
• Fundamental forces


  • Nuclear force
  • Electromagnetic force
  • Gravitational force
• Nuclear forces


  • Governs forces at atomic level
  • Is the strongest of the 3 fundamental forces
• Electromagnetic force


  • Governs forces at molecular level
• Gravitational force


  • Governs forces at large scale – universe
• Nuclear forces holding together the nucleus
• Isotopes


  Same atomic number but different mass number
• Isotopes


  • Hydrogen isotopes
  • Helium isotopes
  • Oxygen isotopes
• Types of radioactive decay


  • Alpha particle
  • Beta particle
  • Gamma ray
• Half-life


  How long it takes before half the remaining number of nuclei has decayed
• Radioactive decay – random events
• Over time – trend develops
• Exponential decrease in number of undecayed nuclei
• After 20 half-lives virtually nothing is left of the element
• Half-lives highly variable between different elements (from seconds to billions of years)
• Fission

  Splitting of nuclei
• Fusion


  Lighter nuclei can undergo fusion
• Fe – has the highest binding energy in the nucleus
• Heavier nuclei than Fe are fissionable
• Fission and fusion of nuclei will release energy (because of the loss or increase in mass)
• Fusion of 2 hydrogen atoms are fused together into 1 helium atom
• Fusion happens in the sun - providing the energy of the sun
• How does nuclear fission work?


  1. Mass of the two fission products is less than the mass of the 235U nucleus

  2. ~30 picojoules (30pJ or 30 x 10 -12J) is released per fission of 235U

  3. 2-3 neutrons are released per fission that can go on and split further 235U atoms

  4. Fission products obtain kinetic energy (from Coulomb forces moving them apart), which is turned into heat when they comes to halt in surrounding material
• Mass Energy – 10 8 times more energy released per atom in nuclear reactions compared to chemical reactions
• Change in mass of the fissile isotope (235U)
• Speed of light = 3 x 10^8 m/s
• The "dual" use of nuclear energy - Controlled chain reactions in nuclear reactors for generating electricity, Uncontrolled chain reactions nuclear bombs – very explosive (nuclear fuel contains 90% 235U)
• Nuclear Power = Good, Nuclear Weapons = Bad
• Only 2 isotopes of uranium found in nature ( 235U and 238U)