1. Lesson 4: Using radiation
What you need to know:
1. The ALARA principle.
2. The different properties of Alpha, Beta and Gamma radiation.
As you may have seen, radioactive materials are used in lots of different areas
and in your home you have a small radioactive source in your smoke detector.
Lots of different industries use radioactive materials, such as hospitals and
nuclear power stations.
People working with radioactive materials should only receive a dose of radiation
that is As Low As Reasonably Achievable (ALARA). This means that all
precautions and safety measures need to be used to make sure that the amount
of radiation they are exposed to is as small as can be. But these safety
measures must also be measured against the cost. If the cost is too high for only
a very small gain, then the safety measures are unlikely to be used. This is
balancing cost against risk.
To reduce their risk and exposure, people working with radioactive materials
should take the following precautions:
1. Use protective equipment. This can be things such as machinery used
to handle radioactive materials.
2. Use safety clothing, such as specially designed clothes and aprons.
3. Use radiation detectors.
In your exam you may be asked what ALARA is. You may also be asked what
precautions people can take to reduce their exposure to radiation.
There are three different types of ionizing radiation, Alpha is the most ionizing,
then Beta and finally, Gamma.
Type of radiation Range in air Stopped by Ionizing power
Alpha (α) 1-2 cm Paper/skin Strong
Beta (β) 5-10 cm Thin sheet of Medium
metal (aluminium)
Gamma (γ) 1-2 metres Thick sheet of Weak
metal (lead)
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2. In your exam you may be asked to complete information in a similar table as the
one above. For example you may be asked to state how Gamma radiation can
be stopped.
Ionizing radiation has a variety of uses, but it is often used to sterilize
objects. For example, surgical equipment in hospitals needs to be
decontaminated to stop cross-contamination of germs. Because ionizing
radiation kills living cells, Gamma radiation is used to sterilize surgical
equipment so it can be reused.
Some foods used to be exposed to ionizing radiation to kill bacteria, to stop the
food going off. Companies are no longer allowed to do this in the UK.
In your exam you may be asked why ionizing radiation is used to sterilize food
and equipment.
Recap:
1. The ALARA principle helps identify effective ways in which people can reduce their
radiation dose when working with radioactive materials.
2. Alpha radiation is the most ionizing, but the easiest to stop. Beta and Gamma
radiation are less ionizing, but harder to stop
3. Gamma radiation can be used to sterilize equipment.
Further information:
1. A clip showing the fight club ‘formula’. This explains the balance between cost and
risk: http://uk.youtube.com/watch?v=q7bEkk5GHwg
© Studydoctor 2009