Dangers of Radiation (Edexcel IGCSE Physics: Double Science)
Revision Note
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AshikaExpertise
Physics Project Lead
Dangers of Radiation
- Ionising radiation can damage human cells and tissues
- 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 reforms
- If a mutated cell is able to replicate itself then a tumour may form
- This is an example of cancer, which is a significant danger of radiation exposure
Diagram showing the damage caused to DNA by ionising radiation. Sometimes the cell is able to successfully repair the DNA, 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
- Because of this, it is important to handle radioactive sources carefully
Handling Radiation Safely
- To mitigate the risks of radiation exposure, there are some safe practices that should be used:
- Radioactive sources should be kept in a shielded container when not in use, for example, a lead-lined box
- Radioactive materials should only be handled when wearing gloves, and with tongs to increase the distance from them
- It may be appropriate to wear protective clothing to prevent the body becoming contaminated
- The time that a radioactive source is being used for should be limited
Regulating Exposure
- Because of the harmful effects of radiation, it is important to regulate the exposure of humans to radiation
- 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
- People would normally receive about 3 mSv (0.003 Sv) in one year
- 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 my radiographers, or anyone working with radiation
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
Differences in Exposure
- The amount of radiation that a person receives is affected by a person’s occupation, lifestyle or location
- Some areas around the world have higher background radiation because they are closer to sources of radiation
- People that work with nuclear radiation receive more radiation
- The UK limit for nuclear industry employees is 20 mSv in one year
- The diagram below compares the dose received by some different activities
All living things emit a small amount of radiation: the amount of radiation within a banana is tiny, and not at all dangerous!
Disposing of Radioactive Waste
- 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
Depending on the activity of radioactive waste, it is buried in different ways
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.
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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