Explain why workers in a nuclear power station are given film badges to wear, and describe what the film badge detects.

OCR GCSE Physics A: Gateway Science (J249) — P4.3 Radioactive emissions · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Workers in a nuclear power station may be exposed to ionising radiation from radioactive materials. To monitor their exposure, each worker wears a film badge at all times whilst on site.

Model answer (4 marks)

Workers in a nuclear power station are given film badges because ionising radiation can damage living cells, body tissue and DNA. The badge monitors the total dose of radiation the worker has been exposed to. It contains photographic film that is darkened or fogged by ionising radiation. The greater the exposure, the darker the film becomes, allowing the dose to be determined – a very dark film indicates a high dose.

Examiner tips

Use the word ‘ionising radiation’ and link it to damage of cells/DNA.
Explain that the badge measures total dose and that the film darkens with exposure.
Mention that the darkness of the film indicates the level of dose.
Keep the answer concise – 4 marks can be earned with 3–4 short points.

Common mistakes

Confusing ionising with non‑ionising radiation.
Saying the badge measures ‘time’ instead of ‘dose’.
Not mentioning that the film darkens or that darkness indicates dose.

Mark scheme (4 marks)

Ionising radiation can damage living cells / body tissue / DNA
The film badge monitors / measures the (total) dose / amount of radiation the worker has been exposed to
The badge contains photographic film that is darkened / fogged by ionising radiation
The greater the exposure to radiation, the darker the film becomes, allowing the dose to be determined / so that if the film is very dark the worker has received too high a dose

Key terms in this question

film badge