4.4.3 Hazards and uses of radioactive emissions and of background radiation

Question 1

Give 4 sources of background radiation.

Answer 1

1. Rocks
2. Cosmic rays from space
3. Nuclear weapon testing
4. Nuclear accidents

Question 2

How should background radiation be dealt with in calculations?

Answer 2

The background count should be subtracted from any readings before calculations (half life etc.) are attempted.

Question 3

What is the unit used to measure radiation dosage?

Answer 3

Sieverts (Sv).

Question 4

How many millisieverts equal 1 sievert?

Answer 4

1000 millisieverts = 1 sievert

Question 5

Why might the radiation dosage that different people experience differ?

Answer 5

● Some occupations involve working with radiation
● Background radiation differs with location due to things such as the locality of nuclear power stations or radiation related testing

Question 6

What factor determines how dangerous a particular radioactive isotope is?

Answer 6

The half-life of the isotope.

Question 7

Why are isotopes with long half-lives particularly harmful?

Answer 7

● They remain radioactive for much longer periods of time
● They must be stored in specific ways to avoid humans and the environment from being exposed to radiation for too long

Question 8

State two uses of nuclear radiation in the field of medicine.

Answer 8

1. Examining of internal organs
2. Controlling and destroying unwanted
   tissue

Question 9

How is radiation used in sterilisation?

Answer 9

Gamma emitters are used to kill bacteria/parasites on equipment.

Question 10

Explain the process of radiotherapy.

Answer 10

● Gamma emitters direct gamma rays at the cancerous cells
● The cancerous cells absorb the radiation and are killed

Question 11

How are medical tracers chosen?

Answer 11

They should have a short half life and decay into a stable isotope which can be excreted.
They should only release gamma radiation since it is weakly ionising and can easily pass through body tissue without damaging it.