Fission and Fusion
5 marks · NormalA nuclear power station can use either a fission reactor or, in the future, a fusion reactor.
State two similarities and two differences between nuclear fission and nuclear fusion as sources of energy.
Suggest one reason why fusion reactors could be more desirable than fission reactors for providing energy on Earth.
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(a) — · must show Both release large energy; both involve change in nuclei; fission splits nuclei, fusion joins nuclei; fission produces radioactive waste, fusion does not
(b) — · must show Fusion does not produce long-lived radioactive waste / fuel is abundant and safe / no CO2
Common mistakes: Giving only one similarity/difference; Not specifying fusion advantages
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Marking points
B1 (a) · 1 mark · States one valid similarity between fission and fusion.
B2 (a) · 1 mark · States a second valid similarity or difference.
B3 (a) · 1 mark · States one clear difference.
M1 (b) · 1 mark · States a plausible reason for fusion’s desirability (e.g. no radioactive waste, abundant fuel).
A1 (b) · 1 mark · Explains why this factor is a benefit for energy supply on Earth.
Worked solution
a) Similarities: • Both release large amounts of energy. • Both involve changes in the nucleus of atoms. Differences: • Fission splits large nuclei into smaller ones; fusion joins small nuclei to form a larger one. • Fission produces radioactive waste; fusion’s waste is minimal and not radioactive.
b) Fusion reactors could be more desirable because fusion produces no long-lived radioactive waste, makes use of abundant fuels such as hydrogen, and does not contribute to greenhouse gas emissions.