Radioactivity (6.43-6.46)

Nuclear fusion

follows specification points

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Describe nuclear fusion (6.43)

  • Nuclear fusion is the creation of larger nuclei resulting in a loss of mass from smaller nuclei, accompanied by a release of energy
  • Fusion is the energy source for stars

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  • When 2 small light nuclei join together to make one heavier nucleus
  • ie. 2 hydrogen nuclei fuse under high temp and pressure to form isotope of helium nucleus
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Compare nuclear fusion and fission (6.44)

  • Nuclear fission is the splitting of a large nucleus into smalle nuclei
  • Nuclear fusion is the joining of 2 smaller, ligher nuclei to form one bigger heavier nucleus
  • both release large amounts of energy
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When fusion can occur (6.45)

  • nuclei are positively charged - they will repel as they approach each other
  • nuclei can only fuse under very high temperatues and pressure in order to force the nuclei together and overcome the electrostatic repulsion
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Fusion not used for power stations (6.46)

  • Fusions need for such high temp and pressure makes it very difficult to build and practical and economic nuclear fusion station
  • all the nuclear reactors in power station use fission to release energy instead
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