Contamination & Irradiation (AQA GCSE Physics)

Revision Note

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Ashika

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Ashika

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Contamination

  • Contamination is defined as:

The unwanted presence of materials containing radioactive atoms on other materials

  • A substance is only radioactive if it contains radioactive atoms that emit radiation
  • Contamination occurs when a radioactive isotope gets onto a material where it should not be
    • This is often due to a radiation leak

  • As a result of this, the small amounts of the isotope in the contaminated areas will emit radiation and the material becomes radioactive

The Assassination of Alexander Litvinenko

  • Contamination is almost always a mistake or an accident
    • However, in 2006 a former Russian spy was poisoned by a radioactive isotope

  • His name was Alexander Litvinenko and he was contaminated with the isotope polonium-210
    • He died because of the poisoning

Poison tea, downloadable IGCSE & GCSE Physics revision notes

It is believed that the polonium-210 that poisoned Alexander Litvinenko was secretly put into a cup of tea he was drinking

Irradiation

  • Irradiation is defined as:

The process of exposing a material to alpha, beta or gamma radiation

  • Irradiating a material does not make that material radioactive
    • However, it can kill living cells

Radiation-Hazard, IGCSE & GCSE Physics revision notes

This sign is the international symbol indicating the presence of a radioactive material

  • Irradiation can be used as a method of sterilisation:
    • Surgical equipment is irradiated before being used in order to kill any micro-organisms on it before surgery
    • Food can be irradiated to kill any micro-organisms within it
    • This makes the food last longer without going mouldy

Exam Tip

Irradiation and contamination are very commonly confused.Remember that something is radioactive only if it contains radioactive atoms. This can only occur from contamination, not from irradiation!

Ashika, Physics Project Lead

Teacher tip

Ashika

Physics Project Lead

In my experience, students find contamination and irradiation super confusing because the language used to describe them is so similar. Describe the differences between contamination and radiation is a really hard exam question if you are not secure in your understanding of each.

Contamination relates to the radioactive substance. If the radioactive substance gets somewhere that it's not supposed to be, that's contamination. It could get on your clothes, it could get inside your body, it could get into the soil where crops are subsequently grown; in all these instances the presence of the radioactive substance is dangerous because when it decays and releases radiation, you will be exposed to that radiation in a way where it can damage your cells. 

Irradiation relates to the radiation itself. If you stand close to a radioactive substance and you get in the path of the radiation, then you are being irradiated. If you build a house on an old nuclear waste site, you would live in the path of the radiation, if you blast a crate of medical supplies with gamma radiation, they are being irradiated. If you ingest a radioactive substance (contamination) then your cells are in the path of the radiation released in the decay and so your cells will be irradiated.

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Ashika

Author: Ashika

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.