# A scientist states: 'Nuclear fusion releases more energy per kilogram of fuel than nuclear fission, yet fusion is not currently used in power stations.' Evaluate this statement by explaining the advantages of fusion over fission and why fusion has not yet been used as a practical energy source.

> WJEC A-Level Physics (Wales) — 3.6 Nuclear energy · Evaluate · 5 marks

## Mark scheme (5 marks)

1. Nuclear fusion releases more energy per kilogram of fuel than fission (accept: fusion has a greater energy output per unit mass)
2. Fusion fuels (such as hydrogen/deuterium/tritium) are more readily available / less rare than uranium used in fission
3. Fusion does not produce long-lived radioactive waste (unlike fission)
4. Fusion requires extremely high temperatures (millions of degrees) to overcome the repulsion between nuclei
5. No material can contain plasma at such high temperatures / it is difficult to contain the reaction for long enough to produce a net energy output

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Evaluate" 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-scientist-states-nuclear-fusion-releases-75f614cb) · Published by Druglandscape Ltd.