AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
Irradiation is the process of exposing an object to nuclear radiation. The…
Full specification wording
Radioactive contamination: Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive.
Irradiation means an object is placed in a radiation field, for example a patient receiving a gamma-ray dose from an external source or food passed through a gamma beam.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 2 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
Irradiation means an object is placed in a radiation field, for example a patient receiving a gamma-ray dose from an external source or food passed through a gamma beam. The object absorbs or scatters some of the radiation, but its atoms do not gain extra radioactive nuclei, so it does not become a source itself. This is different from contamination, where radioactive atoms are left on or in the object. A student should describe how irradiation is produced, how it is detected and controlled, and why the irradiated object can be handled safely once the external source is removed or switched off.
What earns the marks
- Defines irradiation as exposing an object to nuclear radiation from an external source, without the object gaining radioactive atoms.
- States clearly that the irradiated object does not become radioactive because no radioactive material is transferred to it.
- Describes how irradiation is detected or measured, for example using a Geiger–Müller tube or film badge to record dose.
- Explains how distance, shielding and time reduce the dose received by people or objects being irradiated.
- Contrasts irradiation with contamination: irradiation stops when the source is removed, whereas contamination persists while the radioactive atoms remain.
Common mistakes and how to put them right
Claiming that an irradiated object becomes radioactive.
Put it right: Irradiation transfers energy, not radioactive atoms, so the object is not a source after the external source is removed.
Confusing irradiation with contamination.
Put it right: Contamination leaves radioactive material on or in the object, while irradiation only exposes it to radiation.
Ignoring the role of time, distance and shielding.
Put it right: These factors control the dose received during irradiation and should be included in risk explanations.
Exam tips
- Write a one-line contrast: irradiation is being exposed to radiation; contamination is having radioactive atoms on or in the object.
- When explaining safety, refer to reducing time near the source, increasing distance and using appropriate shielding such as lead for gamma.
- Use a familiar example such as sterilising medical equipment with gamma rays, then state that the equipment is safe to use because it is not radioactive.
Try the lesson
The start of the Radioactive contamination: Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive. lesson, made from checked teaching notes for this specification point.
Have a go first
A sealed packet of food is passed through a beam of gamma radiation to kill bacteria. What is this process called?
Listen
Irradiation means an object is placed in a radiation field, for example a patient receiving a gamma-ray dose from an external source or food passed through a gamma beam. The object absorbs or scatters some of the radiation, but its atoms do not gain extra radioactive nuclei, so it does not become a source itself. This is different from contamination, where radioactive atoms are left on or in the object. A student should describe how irradiation is produced, how it is detected and controlled, and why the irradiated object can be handled safely once the external source is removed or switched off. A strong answer earns marks for these points. Defines irradiation as exposing an object to nuclear radiation from an external source, without the object gaining radioactive atoms. States clearly that the irradiated object does not become radioactive because no radioactive material is transferred to it. Describes how irradiation is detected or measured, for example using a Geiger–Müller tube or film badge to record dose. Explains how distance, shielding and time reduce the dose received by people or objects being irradiated. A common slip: Claiming that an irradiated object becomes radioactive. Instead, irradiation transfers energy, not radioactive atoms, so the object is not a source after the external source is removed. Exam tip: Write a one-line contrast: irradiation is being exposed to radiation; contamination is having radioactive atoms on or in the object.
Key words
Say what each word means before you turn the card.
Irradiation
Try answering aloud or in your head before turning the card.
Contamination
Try answering aloud or in your head before turning the card.
Dose control
Try answering aloud or in your head before turning the card.
Irradiated object
Try answering aloud or in your head before turning the card.
See every definition
- Irradiation
- The process of exposing an object to nuclear radiation from an external source, without the object gaining radioactive atoms.
- Contamination
- Where radioactive atoms are left on or in the object, so the radioactive material remains while it stays there.
- Dose control
- Reducing the dose received by people or objects being irradiated by controlling time, distance and shielding.
- Irradiated object
- An object that absorbs or scatters some of the radiation but does not become radioactive, so it can be handled safely once the external source is removed or switched off.
There is more to this lesson
The full lesson goes on to check your understanding and help you earn the marks. Create a free account to carry on, with your progress saved.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge
Test your understanding of Radioactive contamination: Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive.
Active recall beats re-reading. Take an instant quiz now to test what you’ve learned and lock it into long-term memory.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge