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Nuclear fission and fusion - AQAFission reactors

The nuclei of atoms contain a large amount of energy. Releasing this energy would free the world from having to use fossil fuels. There are two methods of doing this: fission and fusion.

Part of Physics (Single Science)Atomic structure

Fission reactors

Cold coolant is injected at the bottom. It passes into reactor vessel and through gaps in graphite core which hold moveable control rods.  The now hot coolant is siphoned out.

A fission reactor contains a number of different parts:

  • (the uranium that will split when triggered by an incoming ) - the fuel is held in rods so that the neutrons released will fly out and cause in other rods
  • - graphite slows the neutrons down so that they are more likely to be absorbed into a nearby fuel rod
  • - these are raised and lowered to stop neutrons from travelling between fuel rods and therefore change the speed of the
  • - this is heated up by the energy released from the fission reactions and is used to boil water to drive in the power station
  • concrete shield - the daughter products of the fission reaction are and can be a

Many of the features of the reactor are designed to control the speed of the reaction and the temperature inside the shielding. An uncontrolled fission reaction is the basis of an .