Nuclear Radiation

What happens to some atomic nuclei?

They’re unstable, give out radiation in order to become more stable

What does the type of radiation emitted depend on?

Why the nucleus is unstable and is a random process - not possible to predict when an atom will decay

What is the activity of a radioactive source?

The rate at which it decays, measured in becquerels (Bq)

What is one becquerel equivalent to?

One decay per second , 1Bq = 1 decay per sec. One count per second, 1Bq = 1 count per sec.

What is the count rate?

The number of decays recorded each second by a detector e.g. Geiger-Muller tube

What are the three main types of nuclear radiation?

• Alpha- absorbed by few cm of air or thin sheet of paper

• Beta- passes through air & paper, absorbed by few mm of aluminium

• Gamma- very penetrating & needs many cm of lead of many metres of concrete to absorb most of it

What are alpha, beta and gamma?

Ionising- capable of knocking electrons from atoms. Alpha is most ionising, gamma least ionising

What is alpha radiation?

• 2 neutrons & 2 protons

• Ejected from nucleus

• Hazards- likely to be absorbed & cause damage if passing through living cells

What is beta radiation?

• High-speed electron

• Ejected from nucleus as a neutron turns into a proton

• Hazards- Likely to damage if absorbed by living cells + can penetrate body inner organs

What is gamma radiation?

• Electromagnetic radiation

• Emitted rom nucleus

• Hazards- Likely to pass through living cells w/o being absorbed and causing ionisation

What is the fourth type of nuclear radiation?

A neutron- can be emitted during radioactive decay

What is radioactive contamination?

• The unwanted presence of materials containing radioactive atoms on other materials

• Contaminated object gives out radiation until decontaminated

What is the hazard from the contamination due to?

The decay of the contaminating atoms

What is irradiation?

• The process of exposing an object to nuclear radiation

• Can be deliberate or accidental

• doesn’t cause object to become radioactive

How can you protect against unwanted irradiation when using radioactive sources?

• Using sources of the lowest activity possible for shortest amount of time

• Wearing appropriate protective clothing e.g. lead apron

• Not handling source with bare hands

What are hazards associated with contamination and irradiation?

• Food contaminated with an alpha source more hazardous than food contaminated with gamma source- alpha more strongly ionising

• Area contaminated with alpha source not dangerous, unless it was entered- low penetration of alpha

• However, contaminated with gamma source, irradiate people nearby