Contamination & Irradiation (OCR Gateway GCSE Physics: Combined Science)

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

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

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

Comparing Contamination and Irradiation

• Irradiation is the process of exposing a material to alpha, beta or gamma radiation
• Contamination is where small amounts of the radioactive isotope leak onto the material
• The only way a material can become radioactive is if that material becomes contaminated
• 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
• 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

  Comparison of Irradiation and Contamination Table

  

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 suits are 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

Lead shielding is used when a person is getting an x-ray, as well as for people who work with radiation. Contamination carries much greater risks than irradiation

Chernobyl Nuclear Disaster

• Chernobyl Nuclear Power Plant is in Ukraine
• In 1986 an incident at the plant caused an explosion
• A large amount of radioactive material was released from the plant and went into the air
• Hundreds of thousands of people were evacuated from the surrounding area to protect them from being contaminated
• An exclusion zone of around 2,600 square kilometres is still in place around the power plant
  • This is because the level of radiation in the area is still very high