Contamination occurs if an object has a radioactive material introduced into it. An apple exposed to the radiation from cobalt-60 is irradiated but an apple with cobalt-60 injected into it is contaminated.
As with irradiation, contamination can be very useful as well as being potentially harmful.
Water supplies can be contaminated with a gamma-emitting radioactive isotope to find leaks in pipes . Where there is a leak, contaminated water seeps into the ground, causing a build-up of gamma emissions in that area. The build-up of gamma emissions can be found using a Geiger-Muller tube. This makes it easier to decide where to dig to find the leak.
The isotope used for this purpose must:
|Advantages of contamination||Disadvantages of contamination|
|Radioactive isotopes can be used as medical and industrial tracers||Radioactive isotopes may not go where they are wanted|
|Use of isotopes with a short half-life means exposure can be limited||It can be difficult to ensure that the contamination is fully removed so small amounts of radioisotope may still be left behind|
|Imaging processes can replace some invasive surgical procedures||Exposure to radioactive materials can potentially damage healthy cells|
The two processes of irradiation and contamination are often confused. However they are very different and useful in their own right.
|Occurs when an object is exposed to a source of radiation outside the object||Occurs if the radioactive source is on or in the object|
|Doesn’t cause the object to become radioactive||A contaminated object will be radioactive for as long as the source is on or in it|
|Can be blocked with suitable shielding||Once an object is contaminated, the radiation cannot be blocked from it|
|Stops as soon as the source is removed||It can be very difficult to remove all of the contamination|