Radioactivity (6.36- 6.42)

Nuclear power and fission

follows specification points


Advantages and disadvantages of nuclear power (6.3


  • Produces no carbon dioxide so it does not contribute to global warming
  • Very small amount of nuclear fuel generates large amount of energy
  • very low fuel costs
  • power station has very long lifetime


  • Waste is radioactive and safe disposal is very difficult and expensive
  • Local thermal pollution from waste water can affect marine life
  • Large scale accident would be catastrophic→so public perception is negative
  • cost of building and safely decommissioning nuclear power lant are very high
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Nuclear reaction (6.37)

  • nuclear reactions, including fission, fusion and radioactive decay, can be a source of energy
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Fission of U-235 (6.38)

  • Rather than emitiing small particles, nuclear fission involves a nucleus splitting into 2 daughter nuclei and 2 or more neutrons. This process releases energy.
  • Although some isotopes fission themselves, more fission needs to be 'induced' by absorbing another particle, usually a neutron.
  • The isotopes mosted used in nuclear reactors are Uranium-235 and Plutonium-239

Fission of U-235 produces 2 daughter nuclei, emits 2 or more neutrons and releases energy

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Controlled nuclear chain reaction (6.39)

Controlled Nuclear Fission

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How chain reaction is controlled (6.40)

  • Fast neutrons scatter from the uranium nucleus, without causing it to split
  • Slow neutrons are absorbed by 235U nucleus, becoming an unstable 236U nucleus which then splits indto two daughter nuclei and two or three neutrons.

Moderators and control rods

  • Moderators slow down the neutrons to optimise fission
  • Controls rods absorb the neutrons to control the rate of the chain reaction. They can be raised or lowered to change the rate, and lowered completely to stop it.

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How thermal energy is used in nuclear power statio

  • The fission reaction releases energy in the form of kinetic energy of the products, which transfers to thermal energy
  • Thermal energy heats water and high pressure steam drives tubines and generators

nuclear power | Definition, Issues, & Facts | Britannica

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Products of nuclear fission (6.42)

  • Products of nuclear fission is radioactive
  • radioactive waste can be radioactive for thousands of years
  • it tends to be stored in containers and buried underground
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