A nuclear power station uses uranium as fuel. Explain how the energy released from nuclear fission in the reactor core is ultimately used to generate electricity.

WJEC A-Level Physics (Wales) — 3.6 Nuclear energy · Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Nuclear power stations generate around 15% of the UK's electricity. The process involves several energy transfers before electrical energy is produced.

Model answer (5 marks)

1. A uranium nucleus captures a neutron and undergoes fission, releasing a large amount of energy.
2. The released energy heats the coolant (usually water) circulating in the reactor core.
3. The hot coolant turns into steam, which is directed onto the blades of a turbine.
4. The turbine rotates, and its shaft is connected to a generator.
5. The generator converts the mechanical rotation into electrical energy that is fed into the grid.

Examiner tips

  • Use the exact sequence of energy transfer steps; each step earns one mark.
  • Mention the role of the turbine and generator explicitly.
  • Keep the answer concise and use correct terminology (fission, coolant, turbine, generator).

Common mistakes

  • Confusing the coolant with the steam; students sometimes say the coolant itself drives the turbine.
  • Omitting the generator step or not stating that it produces electrical energy.
  • Using vague language such as "heat the water" instead of "heat the coolant".

Mark scheme (5 marks)

  1. Uranium nucleus absorbs a neutron and splits (fission occurs), releasing energy
  2. Energy released heats a coolant/water in the reactor core
  3. Hot coolant/steam is used to drive a turbine
  4. Turbine drives/turns a generator
  5. Generator produces/outputs electrical energy

Key terms in this question

nuclear fission

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