Dangers of Radiation (Edexcel IGCSE Physics: Double Science)

• All types of ionising radiation pose a danger if mishandled as they can
  • damage living cells and tissues
  • cause mutations which can lead to cancer

Effect of radiation on a living cell

Ionising radiation can cause damage to DNA. Sometimes the cell can successfully repair the DNA, but incorrect repairs can cause a mutation

• Highly ionising types of radiation are more dangerous inside the body (if a radioactive source is somehow ingested)
  • Alpha sources are the most ionising, so they are likely to cause the most harm to living cells inside the body
  • Gamma sources are the least ionising (about 20 times lower than alpha particles), so they are likely to cause the least harm to living cells inside the body

• Highly penetrating types of radiation are more dangerous outside the body
  • Gamma sources are the most penetrating, so they are able to pass through the skin and reach living cells in the body
  • Alpha sources are least penetrating, so they would be absorbed by the air before even reaching the skin

Safe handling of radioactive sources

• The risks of radiation exposure can be minimised by
  • handing sources of radiation safely
  • monitoring exposure to radiation

• To minimise the risks of contamination, safety practices must be followed, such as:
  • keeping radioactive sources in a shielded container when not in use, for example, a lead-lined box
  • wearing gloves and using tongs to handle radioactive materials
  • wearing protective clothing (particularly if the risk of inhalation or ingestion is high)
  • limiting the time that a radioactive source is outside of its container

• To minimise the risks of irradiation to workers, it is important to monitor their exposure to radiation 
  • To protect against over-exposure, the dose received by different activities is measured
  • A dosemeter measures the amount of radiation in particular areas and is often worn by radiographers, or anyone working with radiation

Badge for monitoring radiation exposure

A dosemeter, or radiation badge, can be worn by a person working with radiation in order to keep track of the amount of radiation they are receiving

Disposal of nuclear waste

• Nuclear waste must be treated appropriately, depending on the type of radiation it emits
  • Alpha-emitting nuclear waste is easily stored in plastic or metal canisters
  • Beta-emitting nuclear waste is stored inside metal canisters and concrete silos
  • Gamma-emitting nuclear waste requires storage inside lead-lined, thick concrete silos

• Radioactive waste of all types tends to emit dangerous levels of radiation for many years, so it must be stored securely for a very long time
• Typically, waste with the highest levels of radioactivity must be buried underground in secure, geologically stable locations

Dealing with radioactive waste

Depending on the type of radiation emitted, nuclear waste is treated in different ways

• Sources with long half-lives present a risk of contamination for a much longer time
• Radioactive waste with a long half-life can be buried underground to prevent radioactive from being released into the environment
• Radioactive waste must be stored in strong containers
  • The containers must be able to withstand harsh conditions over long periods

• Containers must be designed to resist rust and corrosion
  • Rust-proof containers are often expensive and challenging to manufacture

• The disposal site must have high security to prevent unauthorised access
• The location of the disposal site must have a low risk of natural disasters, e.g. earthquakes
• Carefully selecting the site and using strong containers will help prevent radioactive waste from leaking into groundwater
• Radioactive waste can also be diluted in large volumes of seawater
  • This helps to minimise the concentration of radioactive materials