Nuclear Power

• Describe the advantages of nuclear power for generating electricity.

  Nuclear fuels do not produce carbon dioxide. The fuel is readily available, so would reduce strain on the fossil fuel supplies. Less nuclear fuel has to be used to produce the same amount of energy as burning fossil fuels. Does not contribute to global warming.
• Explain some disadvantages of using nuclear power to generate electricity.

  Unpopular - the public perceive nuclear power as very dangerous. Security risks as the radioactive substances can be useful for terrorists. Expensive to commission and decommission the stations - which may be bad for a country's economy. The radioactive waste can be difficult to dispose of an will remain radioactive for many years - which can be dangerous to humans and the environment. 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 (where no neutron absorption occurs) is rare.
• Alongside two smaller nuclei, what else is emitted in a fission reaction?

  Two or three neutrons. Gamma rays. Energy.
• Name a common fissile nuclei.

  Uranium-235.
• What are the 3 main components of the core of a nuclear reactor?

  Fuel rods, Control rods and 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, which results in a chain reaction.
• What is the consequence of an uncontrolled chain reaction?

  The rate of fission events becomes to 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 the fuel rods. 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. The thermal energy is used to boil water and then produce steam. This steam is then used to turn a turbine which starts the generator.
• What is nuclear fission?

  When two light nuclei join to produce a heavier nucleus and release energy.
• Name 2 isotopes of hydrogen which are commonly used in nuclear fission.

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

  Nuclear fusion.
• Explain the difficulty of generating energy through nuclear fusion.

  Fusion requires very high temperatures which in itself requires large quantities of energy. Currently, the production of fusion results in a net loss of energy.
• Give an example of where fusion occurs.

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

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