Applications of Nuclear Radiation (SQA National 5 Physics): Revision Note

Applications of nuclear radiation

• Radioactivity has many uses, such as:

  • Smoke detectors (alarms)

  • Monitoring the thickness of materials

  • Detecting leaks in pipes

  • Generating electricity

  • Medical procedures including diagnosis and treatment of cancer

  • Sterilising food (irradiating food)

  • Sterilising medical equipment

  • Determining the age of ancient artefacts

• The properties of the different types of radiation determine which one is used in a particular application

Smoke detectors

• Alpha particles are used in smoke detectors

• The alpha radiation will normally ionise the air within the detector, creating a current

• The alpha emitter is blocked when smoke enters the detector

• The alarm is triggered by a microchip when the sensor no longer detects alpha

Measuring the thickness of materials

• When a material, such as aluminium foil, moves above a beta source, some beta particles will be absorbed, but most will penetrate

  • The amount of beta particles passing through the material can be monitored using a detector

• If the material gets thicker, more particles will be absorbed, and the count rate will decrease

• If the material gets thinner, fewer particles will be absorbed, and the count rate will increase

• This allows the manufacturer to make adjustments to keep the thickness of the material constant

• Beta radiation is used because the material will only partially absorb it

  • If an alpha source were used, all alpha particles would be absorbed regardless of material thickness

  • If a gamma source were used, almost all gamma rays would be detected regardless of material thickness

Generating electricity

• Nuclear fission is the process of splitting the nucleus of heavy atoms like uranium or plutonium into smaller nuclei

  • This process releases very large amounts of energy

  • This energy is used to heat water

  • The steam produced is used to turn turbines that turn a generator and produces electricity

Diagnosis and treatment of cancer

• Radiotherapy is the name given to the treatment of cancer using radiation

  • Note: this is different to chemotherapy, which is a drug treatment for cancer

• Although radiation can cause cancer, it is also highly effective at treating it

• The relative ionising effect of radiation can kill living cells

  • Some cells, such as bacteria and cancer cells, are more susceptible to radiation than others

• Beams of gamma rays are directed at the cancerous tumour

  • Gamma rays are used as they can penetrate the body and reach the tumour

  • The beams are moved around to minimise harm to healthy tissue whilst still being aimed at the tumour

• A tracer is a radioactive isotope that can be used to track the movement of substances, like blood, around the body

• A PET scan can detect the emissions from a tracer to diagnose cancer and determine the location of a tumour

Sterilising food and medical equipment

• Gamma radiation is widely used to sterilise medical equipment

• Gamma is most suited to this because:

  • It is the most penetrating out of all the types of radiation

  • It is penetrating enough to irradiate all sides of the instruments

  • Instruments can be sterilised without removing the packaging

• Food can be irradiated in order to kill any microorganisms that are present on it

• This makes the food last longer and reduces the risk of food-borne infections