GCSE Physics Unit 2 Revision (17)


Nuclear Fusion and Fission

  • Nuclear fission - the splitting up of atomic nuclei
  • Nuclear power stations and nuclear submarines are both powered by nuclear reactors.
  • In a nuclear reactor, a controlled chain reaction takes place in which atomic nuclei split up and release energy in the form of heat. This heat is then simply used to heat water to drive a steam turbine. So nuclear reactors are really just glorified steam engines. The fuel that's split is usually uranium-235 or plutonium-239 (or both).
  • The Chain Reactions
  • If a slow-moving neutron gets absorbed by a uranium or plutonium nucleus, the nucleus can split.
  • Each time a uranium or plutonium nucleus splits up, it spits out 2 or 3 neutrons, one of which might hit another nucleus, causing it to split also, and thus keeping the chain reaction going.
  • When a large atom splits in…


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