Radiation Flashcards

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1
Q

State one detector of gamma radiation

A
  • Photographic film
  • GM tube
  • Bubble chamber
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2
Q

State one source of gamma radiation

A
  • Stars
  • Some radioactive substances (e.g. Cobalt 60)
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3
Q

State one use for gamma radiation

A
  • Used as a tracer in medicine
  • Used to treat cancer
  • Sterilisation of surgical operating instruments
  • Gamma rays kill microbes and are used to keep food fresher for longer. This is known as “irradiated” food
  • Checking for cracks in aeroplane wings and joints
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4
Q

What are the 3 types of ionising radiation?

A
  • Alpha
  • Beta
  • Gamma
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5
Q

What is alpha radiation?

A

It is a helium nucleus

(2 protons and 2 neutrons)

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6
Q

What is beta radiation?

A

A fast moving electron

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7
Q

What is gamma radiation?

A

It is a high frequency, high energy wave and part of the electromagnetic spectrum

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8
Q

What is meant by ionisation?

A

It is the gain or loss of an electron from an atom

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9
Q

Which is the most ionising radiation?

A

alpha

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10
Q

Which is the least ionising radiation?

A

Gamma

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11
Q

State 3 detectors if ionising radiation

A
  • Photographic film
  • GM tube
  • Scintillation counter
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12
Q

What will absorb alpha radiation?

A

A few centimetres of air or a sheet of paper

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13
Q

What will absorb beta radiation?

A

A few millimetres of aluminium

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14
Q

What will absorb gamma radiation?

A

Several centimetres of lead

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15
Q

What is meant by shielding?

A

Shielding means having something that will absorb radiation between you and the source of the radiation

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16
Q

What will the amount of shielding required depend on?

A

The amount of energy the radiation has

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17
Q

How can you reduce your exposure to radiation when you are working with it?

A
  • Limit the time you have the source out (only get it when you need it)
  • Only handle using tongs
  • Keep the source at arms length
  • Wash hands before & after use
  • Do not eat while handling it
  • Wear lead lined gloves/ apron and safety goggles
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18
Q

What is meant by background radiation?

A

It is the radiation that is all around us

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19
Q

State a source of man-made background radiation

A
  • Nuclear weapons testing
  • Waste from the nuclear power industry
  • Medical uses: having an x-ray, CT scan, etc
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20
Q

State a source of natural background radiation

A
  • Cosmic rays: radiation from the sun and outer space
  • Radon gas: from rocks underground
  • Food: can be slightly radioactive because of the soil it has been grown in
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21
Q

What is meant by absorbed dose?

A

The energy absorbed per unit mass (of tissue)

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22
Q

What is equivalent dose?

A

It is a way of taking into account the absorbed dose and the type of radiation you are exposed to

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23
Q

What is the radiation weighting factor?

A

A number which takes into account the type of radiation you are exposed to

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24
Q

What is the link between the radiation weighting factor and the ionisation caused by a source?

A

The more ionising the radiation, the higher the radiation weighting factor

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25
Q

What is meant by equivalent dose rate?

A

Equivalent dose absorbed per unit time

26
Q

Give 2 uses for ionising radiation

A
  • Gamma rays are used for radiotherapy which can treat cancer
  • Thickness control of paper or metal sheeting
  • Gamma can be used to sterilise medical instruments
  • Radio-carbon dating
  • Tracers - used in industry in pipes to detect cracks or in the human body to check for blockages
27
Q

What is meant by the activity of a source?

A

It is the number of radioactive decays per second

28
Q

What is meant by the half-life of a source?

A

It is the time it takes for the activity of a source to decrease by half

29
Q

Describe how to calculate the half life of a source from a graph

A
  • Choose a ‘nice’ starting value e.g. 20,000 Bq
  • Find the time that this happens at e.g. 0 hours
  • Once a half life has passed, the activity will be 20,000/2 = 10,000 Bq
  • Find the time that this happens at from the graph - 12 hours
  • Calculate the time for the change as 12 - 0 = 12 hours
30
Q

What is meant by fission?

A

A nucleus of a large mass number splits into 2 nuclei of smaller mass numbers with the release of energy and neutrons

31
Q

What is meant by fusion?

A

2 nuclei of smaller mass numbers combine to form a nucleus of larger mass number with the release of energy

32
Q

What is the fuel in a nuclear fission reactor?

A

Uranium

33
Q

How does a nuclear fission power station produce electrical energy?

A
  • The reactor uses fission of uranium to produce large amounts of heat energy
  • The heat energy is used to heat water
  • The heated water turns into steam and is piped to a turbine
  • The steam makes the turbine turn (heat energy transferred to kinetic energy)
  • The turbine turns a generator to create electrical energy (kinetic energy transferred to electrical energy)
34
Q

Give an advantage of producing electricity using a nuclear fission reactor

A
  • Do not produce greenhouse gases
  • Do not rely on fossil fuels which a in short supply
  • Huge amounts of energy are produced from a small amount of fuel
  • Small amount of waste produced
  • Reliable source of energy (unlike solar or wind)
35
Q

Give a disadvantage of producing electricity using a nuclear fission reactor

A
  • The waste produced is radioactive
  • It has to be stored safely for a long time
  • Uranium in a non renewable fuel
  • Risk of radioactive materials being released into the environment if there is an accident
  • Expensive to decommission nuclear power stations at the end of their useful life
36
Q

What are the products in a fission reaction in a nuclear reactor?

A
  • Fission fragments (smaller mass nuclei/daughter nuclei)
  • Heat energy
  • More neutrons
37
Q

What particles are found in the nucleus?

A

Protons and neutrons

38
Q

What is the charge on a proton?

A

Positive

39
Q

What is the charge on a neutron?

A

No charge

40
Q

What is the charge on an electron?

A

Negative

41
Q

In an atom, which particle orbits the nucleus?

A

Electron

42
Q

What are the main parts of an atom?

A

See diagram

43
Q

What is the charge on an alpha particle?

A

Positive

44
Q

What is the charge on a beta particle?

A

Negative

45
Q

What is the charge on a gamma ray?

A

No charge

46
Q

What precautions should be taken when storing a radioactive source?

A
  • Source should be clearly labelled as to type
  • Stored in lead lined boxes
47
Q

What is meant by corrected count rate?

A

It is when background radiation is subtracted from the radiation measured so that the reading is caused by the source only and not the background radiation

48
Q

Which line on the graph represents the corrected count rate? Give a reason for your answer

A

The dotted red line

The corrected reading is lower than the other reading as background has been subtracted

The graph shows a 0 reading count rate. This is not possible as there is always background radiation present so must be the corrected graph

49
Q

What is the annual effective dose of the average annual background radiation in the U.K.?

A

2.2 mSv

50
Q

What is the annual effective dose limit for a member of the public?

A

1 mSv

51
Q

What is the annual effective dose limit for a radiation worker?

A

20 mSv

52
Q

What is the impact of ionising radiation on living cells?

A

It can kill them

53
Q

State one method of monitoring exposure to radiation

A

Radiation film badge

54
Q

Explain how a radiation film badge is used to monitor the exposure to radiation

A

The darker the photographic film turns on the badge, the more radiation it has been exposed to

55
Q

State the equipment you would need to measure the half life of a source

A
  • Timer
  • GM tube and counter
  • Source of radiation
56
Q

Explain an experiment to measure the half life of a source

A
  • With no source present, record the number of counts in 1 minute using the GM tube and counter.
  • This is the background radiation.
  • Put source in position.
  • The stop clock and the counter are started at the same time
  • Take a reading of the counts per minute every minute.
  • Do this for 10 minutes
  • The background radiation is subtracted from each of the readings so that the counts per minute for the source only are recorded
  • A graph is plotted of counts per minute against time.
  • The half-life is calculated from the graph
57
Q

Where does the energy come from in a fission and a fusion reaction?

A

Some of the mass is converted into energy

58
Q

What is meant by a chain reaction?

A

A neutron causes fission and releases more neutrons. The neutrons produced in the fission reaction go on to cause their own fission reactions

59
Q

State 2 issues that must be overcome in fusion reactors

A
  1. The high temperatures required
  2. The high pressures required
60
Q

Why is containment an issue for fusion reactors?

A

The high temperatures of the plasma would vaporise any materials that we currently know

61
Q

State an advantage of a fission reactor

A
  • Releases massive amounts of energy
  • It is sustainable (unlikely to run out of fuel)
  • No greenhouse gases
  • No risk of meltdown
62
Q

Explain how a fusion reactor could generate electrical energy

A
  • At high temperature and pressure small nuclei join together
  • This releases huge amounts of heat (nuclear energy transferred to heat energy)
  • The heat energy is used to heat water and turn it into steam
  • The steam is used to turn a turbine (heat energy transferred to kinetic energy)
  • The turbine is used to turn a generator (kinetic energy transferred to electrical energy)