AQA GCSE Radioactive Contamination and Irradiation
Radioactive Contamination
Radioactive contamination is the unwanted presence of materials
containing radioactive atoms on other materials.
A piece of wood contains both carbon-12 atoms and carbon-14 atoms. Carbon-12 is stable, but carbon-14 is not stable, so it undergoes radioactive decay.
As the wood contains carbon-14 which is radioactive, it is said to be contaminated.
Any material contaminated by radioactive isotope atoms is considered to be radioactive.
So, contaminated materials will emit radiation as alpha, beta or gamma.
Alpha emitters emit the most ionising form of radiation, which is hazardous, but it is not penetrating. However, if you consume an alpha emitter, it can be very hazardous because the radiation cannot escape the body due to low penetration.
Gamma emitters are the least ionising, so lower hazard. However, they are the most penetrating, so they will pass through you.
Irradiation
Irradiation occurs when a material is exposed to ionising nuclear radiation such as alpha, beta or gamma, but does not become radioactive.
However, because the material does not contain radioactive atoms, it is not itself radioactive.
Some prepacked salads undergo irradiation, to kill bacteria. This means they stay fresher for longer. However, they are not radioactive afterwards and perfectly safe to eat. After the salad passes through the irradiation device there are fewer bacteria.
Practice Questions
1. Define the term contamination
2. Define the term irradiation
3. Using the table below, assign each example as either contamination or irradiation
| Description | Contamination or Irradiation |
|---|---|
| Radioactive waste leaking from a drum onto a concrete floor | |
| Gamma rays being used to sterilse medical equipment | |
| Chernobyl nuclear power plant explosion | |
| A patient undergoing radiotherapy to kill a cancerous tumour |
Absorption and Emission of EM Radiation
JJ Thomson and Plum pudding model
Ernest Rutherford and the Nuclear Model
Niels Bohr changing the Nuclear Model
Discovering the Proton and Neutron
Measuring radiation from radioactivity
Radiation types and properties
Random nature of radioactive decay
Radioactive contamination or irradiation
Hazards of contamination and irradiation
Studies on the effects of radiation on humans
Different half lives of radioactive isotopes
Nuclear Fission Chain Reaction
Writing nuclear fission equations