Contamination & Irradiation (Oxford AQA IGCSE Physics)

Contamination & Irradiation

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

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

Symbol warning of potential irradiation

• 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

Hazards of irradiation & contamination

• Although irradiation can cause harm, contamination has the potential to cause far more harm, due to the continuous exposure to radiation that it will produce

• The hazard from contamination arises from the contaminating atoms decaying

  • The level of hazard this poses depends on the type of radiation the decaying atom emits

• Contamination is particularly dangerous if a radioactive source gets into the human body

  • The internal organs will be irradiated as the source emits radiation as it moves through the body

Protecting against irradiation and contamination

• It is important to reduce the risk of exposure to radiation

• Radiation can mutate DNA in cells and cause cancer

• Shielding is used to absorb radiation

  • Lead lined clothing is used to reduce irradiation for people working with radioactive materials

  • The lead absorbs most of the radiation that would otherwise hit the person

• To prevent contamination an airtight suit is used by people working in an area where there may have been a radiation leak

  • This prevents radioactive atoms from getting inside the person

Protection from radiation

Comparison of Irradiation and Contamination Table