Contamination vs Irradiation

This lesson explains the crucial difference between radioactive contamination and irradiation, the risks associated with each, the safety precautions taken by workers, and the practical uses of radiation in medicine, industry and agriculture. This is an important topic in the Edexcel GCSE Combined Science specification (1SC0) that is frequently tested in exams.

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Irradiation

Irradiation is the process of exposing an object (or person) to radiation from a source outside the body. The object does not become radioactive itself.

Key point	Detail
Definition	Exposure to radiation from an external source
Does the object become radioactive?	No
Can it be controlled?	Yes — by removing the source, increasing distance, or using shielding
Example	Having an X-ray at a hospital; standing near a sealed radioactive source

Controlling Irradiation

The three key principles are:

1. Time — minimise the time spent near the source.
2. Distance — maximise the distance from the source (radiation intensity decreases with distance).
3. Shielding — place absorbing material (e.g. lead, concrete) between the source and the person.