P4 - Uses of Radiation & Background Radiation

Question 1

What are some uses for tracers besides medical uses?

Answer 1

Radioactive isotopes can be used to track the movement of waste materials, find the route of underground pipe systems or detect leaks or blockages in pipes.

Question 2

How can radioactive tracers be used to check a pipe?

Answer 2

• First you squirt the radioactive isotope in, then go along the outside with a detector.
• if the radioactivity reduces, or stops after a certain point, there must be a leak or blockage there.

Question 3

Why are radioactive tracers more useful for checking pipes?

Answer 3

• They are really useful for concealed or underground pipes, there is no need to dig up the road to find the leak, which can be expensive.

Question 4

What type of radiation must the isotope be & why?

Answer 4

The isotope must a gamma emitter, so that the radiation can be detected even through metal or earth which may be surrounding the pipe.
- alpha and beta radiation wouldn’t be much use because they are easily blocked by any surrounding material.

Question 5

Why must the radiation used in checking leaks have a short half life?

Answer 5

• It should have a short half life so as not to cause a hazard if it collects elsewhere.

Question 6

How do smoke detectors work?

Answer 6

• A weak alpha radioactive source is placed in the detector, close to two electrodes.
• The source causes ionisation of the air particles which allows a current to flow.
• If there is a fire, then smoke particles are hit by the alpha particle instead
• This causes less ionisation of the air particles, so the current is reduced, resulting in the alarm sounding.

Question 7

What are the four locations background radiation can come from?

Answer 7

• Naturally occurring unstable isotopes which are all around us, in the air, in food, in building materials, , and in the rocks under our feet, a large proportion of this radiation comes from these natural sources
• Radiation from space, cosmic rays mostly from the sun.
• Radiation due to human activity, e.g. fallout from nuclear explosions or waste from industry and hospitals , but this only represents a small proportion of the total.
• The amount of background radiation can vary depending on your job and location.

Question 8

How can background radiation vary with location and job?

Answer 8

• If you work in an industry that uses radiation, it will result in more radiation exposure.
• If you are on an aeroplane, you are exposed to more cosmic rays
• The rock your house is built on, some rocks are more radioactive than others.