Nuclear Power

• Advantages of nuclear power

  No carbon dioxide produced, extremely high amount of energy per kg of fuel, reduces strain on fossil fuels supplies, does not contribute to global warming
• Disadvantages of nuclear power

  Unpopular as it is perceived as very dangerous, expensive to commission, radioactive waste is difficult to dispose of, risk of nuclear accidents
• What is nuclear fission?

  The splitting of large, unstable nuclei to form smaller more stable nuclei (+ the emission of spare neutrons).
• What usually needs to happen to induce fission?

  The unstable nuclei must absorb a neutron, spontaneous fission (no neutron absorption) is rare.
• Alongside two smaller nuclei, what else is emitted in a fission reaction?

  Two or three neutrons, gamma rays, energy
• Common fissile nuclei

  Uranium-235
• Three main components of a nuclear reactor

  Fuel rods, control rods, moderator
• What takes place during a chain reaction in a nuclear reactor?

  An unstable nucleus absorbs a neutron, the nucleus undergoes fission and releases 2 or 3 further neutrons, these induce more fission resulting in a chain reaction.
• Consequence of an uncontrolled reaction

  The rate of fission events becomes too high and results in the production of too much energy, this can lead to a nuclear explosion.
• How is the chain reaction in a fission reactor kept under control?

  Control rods are positioned in between each fuel rod, the rate of fission is controlled by moving these rods up and down. The lower the rods are inserted, the slower the rate of fission.
• What is the role of the moderator in a nuclear reactor?

  To slow down the neutrons so they are travelling at speeds which allow them to be absorbed by fissile nuclei and cause fission.
• How is electricity produced in a nuclear power station?

  The reactions release thermal energy, boiling water to produce steam that turns a turbine, starting a generator.
• What is nuclear fusion?

  When two light nuclei join to produce a heavier nucleus and release energy.
• Isotopes of hydrogen commonly used in nuclear fusion.

  Deuterium and Tritium
• What releases more energy, nuclear fission or nuclear fusion?

  Nuclear fusion
• Why is it difficult to generate energy through nuclear fusion?


  Requires very high temperatures which in itself requires large quantities of energy, with current technology nuclear fusion results in a net loss of energy.
• Where does nuclear fusion occur?

  In the sun - stars use fusion as an energy source.
• Why does nuclear fusion require so much energy?

  Because both nuclei are positive therefore a lot of energy is required to overcome the electrostatic repulsion between the two nuclei.