Nuclear Fusion (Edexcel IGCSE Physics) : Revision Note

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Nuclear fusion

  • Small nuclei can react to release energy in a process called nuclear fusion

  • Nuclear fusion is defined as:

    When two light nuclei join to form a heavier nucleus

  • This process requires extremely high temperatures to maintain

    • This is why nuclear fusion has proven very hard to reproduce on Earth

  • Stars, including the Sun, use nuclear fusion to produce energy

    • Therefore, fusion reactions are very important to life on Earth

  • In most stars, hydrogen atoms are fused together to form helium and produce lots of energy

nuclear fusion, IGCSE & GCSE Physics revision notes

Two hydrogen nuclei are fusing to form a helium nuclei

  • The energy produced during nuclear fusion comes from a very small amount of the particle’s mass being converted into energy

  • The amount of energy released during nuclear fusion is huge

    • The energy from 1 kg of hydrogen that undergoes fusion is equivalent to the energy from burning about 10 million kilograms of coal

Differences between fusion and fission

  • The following table summarises some of the key differences between fusion and fission:

Comparison of fusion and fission table

 

Fusion

Fission

the process of...

nuclei joining together

nuclei splitting

nuclei are

small e.g. hydrogen

large e.g. uranium

occurs in

stars

nuclear reactors

produces

a large amount of energy

larger nuclei (usually stable and not radioactive)

a large amount of energy

smaller daughter nuclei (usually unstable and radioactive)

2 or 3 neutrons

requires

very high temperatures

very high pressures

thermal neutrons to induce fission

 

  • Nuclear fission reactors are an increasingly common method of electricity generation on Earth

  • Nuclear fusion reactors are not yet a commercially viable method for generating electricity, but they are in development

  • In the future, fusion reactors are likely to have several advantages over fission reactors

Advantages of fusion reactors 

  • Nuclear fusion reactions are capable of generating more energy than fission reactions (per kilogram of fuel)

  • The nuclear fuel required for fusion (isotopes of hydrogen found in water) is more abundant than the fuel required for fission (uranium and plutonium)

  • Nuclear fusion produces no long-lived nuclear waste products

Disadvantage of fusion reactors

  • The conditions for nuclear fusion are much harder to achieve and maintain on Earth than fission

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Ashika

Author: Ashika

Expertise: Physics Content Creator

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.

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