# A nuclear power station uses uranium as a fuel for nuclear fission. Explain how a chain reaction is set up in a nuclear fission reactor and why the process releases large amounts of energy.

> OCR A-Level Physics A (H556) — 6.2 Electric and magnetic fields · Explain · 5 marks

> Nuclear power stations generate electricity by harnessing energy released during nuclear fission. Uranium nuclei are used as the fuel because they are large and unstable, making them suitable for fission reactions.

## Mark scheme (5 marks)

1. A neutron is absorbed by a large, unstable uranium nucleus
2. The unstable nucleus splits into two smaller nuclei (fission products)
3. Two or three neutrons are released during the fission
4. The released neutrons are absorbed by other uranium nuclei, causing further fission events — setting up a chain reaction
5. Energy is released because mass is converted into energy (mass-energy equivalence) / energy is released as electromagnetic radiation with each fission event

## Key terms

- [nuclear fission](https://www.gradenine.co.uk/glossary/nuclear-fission)
- [chain reaction](https://www.gradenine.co.uk/glossary/chain-reaction)

## Related

- [Revision notes for OCR A-Level Physics A (H556)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-nuclear-power-station-uses-uranium-1c33e67f) · Published by Druglandscape Ltd.