Dangers of Radiation (Cambridge (CIE) IGCSE Physics)

Dangers of radioactivity

• Ionising nuclear radiation can damage living things such as human cells and tissues at high doses:

• This can include:

  • Cell death

  • Mutations

  • Cancer

• If the atoms that make up a DNA strand are ionised, then the DNA strand can be damaged

• If the DNA is damaged, then the cell may die, or the DNA may be mutated when it is replicated

• If a mutated cell replicates itself then a tumour may develop

  • This is an example of cancer, which is a significant danger of radiation exposure

Ionising DNA is a danger of radioactivity

Diagram showing the damage caused to DNA by ionising radiation. Sometimes the cell is able to repair the DNA during replication successfully, but incorrect repairs can cause a mutation

• Acute radiation exposure can have other serious symptoms:

  • It can cause skin burns, similar to severe sunburn

  • Radiation can reduce the amount of white blood cells in the body, making a person more susceptible to infections by lowering their immune system

• Because of this, it is very important to handle radioactive sources carefully

Safe storage

• Radioactive materials are moved, used and stored in a safe way

Safe handling to minimise the dangers of radioactivity

• The risks associated with handling radioactive sources can be minimised by following a few simple procedures:

  • Store the sources in lead-lined boxes and keep them at a distance from people

  • Minimise the amount of time you handle sources and return them to their boxes as soon as you have finished using them

  • During use, keep yourself (and others) as far from the sources as possible.

  • When handling the sources do so at arm’s length, using a pair of tongs

 A sign indicating the dangers of radioactivity

Radioactivity warning sign

Safe transportation to minimise the dangers of radioactivity

• Radioactive materials such as used nuclear fuel are transported in special containers called casks

• These casks can withstand extreme conditions such as fire, cold and being submerged in water

Disposing of radioactive waste to minimise the dangers of radioactivity

• If an isotope has a long half-life then a sample of it will decay slowly

  • Although it may not emit a lot of radiation, it will remain radioactive for a very long time

• Sources with long half-life values present a risk of contamination for a much longer time

• Radioactive waste with a long half-life is buried underground to prevent it from being released into the environment

Correct disposal of radioactive waste reduces the dangers of radioactivity

Radioactive waste with long half-lives is buried deep underground

Safety precautions

Extended tier only

• Safety precautions for all ionising radiation include:

  • reducing exposure time

  • increasing the distance between the source and living tissue

  • using shielding to absorb radiation

Reducing exposure time reduces the dangers of radioactivity

• Limiting the amount of time spent near a radioactive source reduces the amount of radiation dose received

• The amount of radiation received by a person is called the dose and is measured in sieverts (Sv)

• One sievert is a very big dose of radiation

  • It would cause acute radiation poisoning

Increasing the distance reduces the dangers of radioactivity

• Increasing the distance the radiation is away greatly reduces the size of the dose received

  • Using tongs instead of your hand when handling a radioactive source can help with this

• Constructing nuclear power plants in remote areas increases their distance from people if there is a problem

• Burying nuclear waste far from places where people live also increases the distance to people

Shielding reduces the dangers of radioactivity

• Radiation shielding is a barrier placed between a radiation source and a person or area to protect them

  • The purpose of shielding is to limit exposure to radiation at a certain location or time

• Barriers absorb the energy from radioactive sources

• Barriers are normally made of lead, water or concrete
  

  • People handling radioactive sources should wear a lead apron to reduce their exposure

• When X-rays are taken:

  • the area around where the image is needed is shielded

  • the radiologist stands behind a barrier or leaves the room

Reducing the dangers of radiation for a radiologist

A radiologist can stand behind a lead barrier to reduce the amount of radiation they are exposed to