Uses & Dangers of Radioactivity

Nuclear Radiation can be very dangerous - but it can be really useful too. You've just got to be careful about what isotope you choose to use!

What is Alpha Radiation used for? [1]
- Smoke Detectors
  - How do smoke detectors use alpha radiation? [3]
    - There is a weak source of alpha-radiation which ionises the air close to two electrodes.
    - The ionised air is a conductor and allows a current to flow between the electrodes
    - If there is a fire, the smoke absorbs the radiation and the current can no longer flow, triggering the smoke alarm!
What is Beta Radiation used for? [2]
- Medical Tracers
  - What are medical tracers? [1]
    - A radioavtive isotope that is injected into a patient (or swallowed) and its progress around the body can be tracked by an external detector.
    - E.g. Iodine-131 is absorbed by the thyroid gland and the radiation given off can be detected to indicate whether the thyroid gland is taking in iodine as it should.
  - What is one advantage and disadvantage of using a medical tracer? [2]
    - Advantage: Avoids the need for intrusive surgery to "see" inside you
    - Disadvantage: Beta radiation is slightly ionising and there is a risk of damage to living tissue if exposed for too long
  - Approximately what half-life must medical tracers have and why? [2]
    - A very short half-life - i.e. a few hours
    - This is so the radioactivity inside the patient quickly disappears
  - Why can tracers be beta or gamma emitters but never alpha emitters? [3]
    - The radiation must be able to pass out of the body to be detected
    - Beta and Gamma can penetrate through the body. Alpha can not - so it would be useless for detecting.
    - Alpha radiation is also strongly ionising which makes it really harmful if it gets inside you
- Thickness Gauges
  - How is beta radiation used to control the thickness of materials such as paper? [3]
    - Radiation is directed through the material being made (e.g. paper or cardboard) and a detector is placed on the other side
    - When the amount of radiation detected changes, it means the material is becoming too thick or thin
    - The control unit adjusts the rollers to give the correct thickness
  - Does the radioactive source need a short or long half-life? [1]
    - A long half-life so it doesn't decay away too quickly
  - Why does the source need to be a beta emitter and not an alpha or gamma emitter? [2]
    - Alpha radiation would not be able to penetrate the material to reach the detector on the other side
    - Gamma radiation would be too penetrating and would not be affected at all as the thickness changes
What is Gamma Radiation used for? [3]
- In Hospitals
  - High doses of gamma rays will kill living cells! What could gamma rays possibly be used for in hospitals? [3]
    - medical tracers
    - treating cancers (radiotherapy to kill the cancer cells)
    - sterilising medical instruments (by killing the microbes)
- Industrial Tracers
  - How could you use an industrial tracer to look for a leak in an underground pipe? [2]
    - Squirt a gamma-source into the pipe and let if flow along
    - If there's a crack in the pipe, the gamma-source will collect outside the pipe and there will be extremely high radioactivity at that point
  - What is an advantage of using a tracer in industry? [1]
    - It is cheaper than digging up the ground to look for leaks in pipes
  - Should the half-life be short or long? [1]
    - Short half-life so as not to cause a long-term hazard if it collects somewhere
  - Why must the isotope used be a gamma emitter and not an alpha or beta emitter? [2]
    - Gamma-radiation is able to be detected through any rocks or earth surrounding the pipe
    - Beta or Alpha radiation would be too easily blocked
- Non-Destructive Testing in Industries
  - What are some examples of this? [1]
    - E.g. airlines use gamma-rays on turbine blades of jet engines to check if the blade is cracked or if there's a fault in the welding

What are the risks of radiation...
- When it is outside your body? [2]
  - Beta and Gama radiation can penetrate the skin and soft tissues to reach the delicate organs inside the body.
  - Alpha radiation can't penetrate the skin and so they are harmless outside the body
- When it is inside your body? [2]
  - Beta and Gamma sources are less dangerous inside the body - their radiation motly passes straight out without doing much damage.
  - If alpha radiation gets inside your body (i.e. by swallowing or breathing it in), alpha sources do all their damage in a very localised area
- What are the side-effects of low doses of radiation on the body? [2]
  - Minor damage without cell death
  - Can cause mutant cells which divide uncontrollably (cancer)
- What are the side-effects of high doses of radiation on the body? [2]
  - Cell death
  - Radiation sickness (if a large part of your body is affected at the same time)
  - (Alexander Litvinienko, the Russian Spy, died of radiation poisoning after swallowing a highly radioactive alpha-source)
- Why does radiation damage or kill living cells? [1]
  - When Radiation collides with molecules in your cells, they cause ionisation
  - This damages or destroys the molecules
- How can you protect yourself? [3]
  - wear full protective suits to prevent inhalation of radioactive particles and prevent radioactive particles lodging to skin or under fingernails, etc
  - work with Lead-lined suits, lead/concrete barriers, thick lad screens to prevent exposure to gamma rays (alpha and beta are stoped much more easily)
  - use remote-controlled robot arms to limit exposure to skin and keep your distance from the source
How do you safely dispose radioactive waste...
- That is slightly radioactive? [1]
  - bury it in secure landfill sites
- That is very radioactive [3]
  - seal it into glass blocks
  - then seal that in metal canisters
  - then bury it deep under ground in a place that does not suffer from earthquakes (geologically stable)

Classwork
- 1) State which types of radiation are used in each of the following and explain why: a) medical tracers, b) treating cancer, c) detecting faults in aeroengine turbine blades, d) sterilisation, e) smoke detectors, f) thickness control
- 2) Briefly describe one more use of nuclear radiation
- 3) Why is nuclear radiation dangerous to living organisms?
- 4) Explain how radiation damages the human body - a) at low doses, b) at high doses
- 5) Describe what precautions you should take to protect yourself from alpha radiation, in a school lab
- 6) Describe what precautions you should take to protect yourself from gamma radiation if you are working with it in industry
- 7) Explain why radioactive waste is difficult to dispose of safely
- 8) Radiation can be used to sterelise surgical instruments. What kind of radioactive source is used, and why? (In your answer, mention the type of radiation emitted (alpha, beta, gamma) and the half-life of the source)
- 9) Similar radiation can be used to treat fruit before it is exported from South Americ to Europe, to stop it going bad on the long journey. How does irradiating the fruit help?
- 10) Gamma radiation can be used to test turbine blades in jet engines. Explain how the test would detect a crack in the turbine blade and how is this method preferable to hitting the blades with a hammer to test their strength?
Homework
- 1) The three different types of radiation can all be dangerous
  - Which type of radiation is usualy most dangerous if it's inhaled or swallowed?
  - What effects can this type of radiation have on the human body?
- 2) In industry, highly penetrating sources sometimes need to be moved from place to place
  - How can this be done without endangering the workers?
  - Gamma radiation can pass easily through the walls of buildings. How can workers in the surrounding areas be protected from this hazard?
- 3) The following sentences explain how a smoke detector works, but they are in the wrong order. Put them in order
  - ? - The circuit is broken so no current flows
  - 1 - The radioactive source emits alpha particles
  - ? - A current flows between the electrodes - the alarm stays off
  - ? - The alarm sounds
  - ? - The air between the electrodes is ionised by the alpha particles
  - ? - A fire starts and smoke particles absorb the alpha radiation
- 4) The diagram shows how beta radiation can be used in the control of paper thickness in a paper mill.
  - Why is beta radiation used rather than alpha or gamma?

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Uses & Dangers of Radioactivity

Nuclear Radiation can be very dangerous - but it can be really useful too. You've just got to be careful about what isotope you choose to use!

What is Alpha Radiation used for? [1]

What is Beta Radiation used for? [2]

What is Gamma Radiation used for? [3]

What are the risks of radiation...

How do you safely dispose radioactive waste...

Classwork

Homework