GCSE Combined Science (AQA)

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Contamination

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Atomic structure Atoms and nuclear radiation

Contamination

2:59 Contamination and Irradiation
Spec 4.4.2.4
Previous Half-Life Calculations Next Irradiation
  • Radioactive contamination is the unwanted presence of radioactive isotopes in materials.
  • Example: Water contaminated with radioactive iodine particles.
  • Important to distinguish contamination from radiation for exams.
  • Nuclear power stations can contaminate surroundings after accidents.
  • Radioactive materials can contaminate water and soil, affecting food chains.
  • Real-life examples: Chernobyl (1986) and Fukushima (2011).
  • Nuclear power stations have extensive safety features; accidents are rare.
  • Contamination is dangerous due to unknown radiation exposure levels.
  • Example: A contaminated tree can unknowingly irradiate a person sitting under it.
  • Controlled radiation exposure is possible in medical settings.
  • Contamination risk depends on the half-life of the isotope.
  • Half-life: Time taken for radioactive activity to halve.
  • Different isotopes have different half-lives.
  • Short half-life isotopes (e.g., iodine-131) cause high irradiation quickly.
  • Long half-life isotopes (e.g., cesium-137) persist longer but irradiate less.
  • Short half-life isotopes are high risk; long half-life isotopes are low risk.
  • Exams may require describing and comparing contamination risks of different isotopes.

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