Dangers of Radiation (Edexcel IGCSE Physics)
Revision Note
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Dangers of ionising radiation
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
Worked Example
A student plans to use a gamma source to conduct an experiment.
List four things that the student should do in order to minimise the risk to themselves when using the source.
Answer:
Any four from:
Keep the source in a lead lined container until the time it is needed
Use tongs to move the source, rather than handling it directly
The source should be kept at as far a distance from the student as possible during the experiment
The time that the source is being used should be minimised
After the experiment the student should wash their hands
The date and the time that the radiation has been used for should be recorded
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