Contamination and irradiation

Question 1

irradiation

Answer 1

ionising radiation from an external radioactive source travelling to the body - it is not breathed in, eaten, or drunk

the source does not come into contact with the person

irradiation does not refer to non-harmful rays from tvs, lights, or other non-ionising sources

Question 2

dangers of irradiation/types of radiation that are dangerous

Answer 2

it could be in the form of gamma rays, beta particles, or x-rays

alpha particles are unlikely to be harmful due to the short range in air (5cm)

cells may become damaged or killed, but you will not become radioactive

Question 3

contamination

Answer 3

the source has to come into contact with the skin, or be taken into the body

external contamination occurs when radioactive materials come into contact with a person’s hair, skin, or clothing

internal contamination occurs when a radioactive source is eaten or drunk
some nuts, plants, fruit or alcoholic drinks have low levels of radioactivity
this is due to the radioactive minerals that they are exposed to during their growth or manufacture

Question 4

State what type of contamination the following examples are describing:

a) eating radioactive strontium-90 that is found in some foods [1]
b) being exposed to cosmic rays from the Sun [1]
c) having an X-ray to find out if a bone is broken [1]
d) radioactive dust comes into contact with the skin [1]

Answer 4

a) internal contamination
b) irradiation
c) irradiation
d) external contamination

Question 5

Define

a) irradiation [2]
b) contamination [2]

Answer 5

a) irradiation is the exposure of the body to ionising radiation from a source that is outside the body
b) contamination is exposure to ionising radiation from a source that is taken into the body by eating, drinking, breathing, injection or by contact with ionising radiation on the surface of the skin

Question 6

Explain why alpha particles are more likely to cause damage inside the body rather than outside the body [3]

Answer 6

alpha particles are highly ionising due to their charge and mass, and will cause damage inside the body as they have a short range and will come into contact with cells

outside the body they are unlikely to reach the body as they have a range of only 5 cm in air and so cannot reach the body to cause any ionisation in cells

Question 7

Explain why background radiation is a mixture of contamination and irradiation [2]

Answer 7

some sources of background radiation do not come into contact with the body, such as cosmic rays from the Sun and medical X-rays, but other sources such as radon gas and radioisotopes in food are taken into the body