# A worker at a nuclear waste facility handles two different radioactive isotopes. Isotope P is an alpha emitter with a long half-life. Isotope Q is a beta emitter with a short half-life. The worker is concerned about the hazards of both isotopes. Explain which isotope presents the greater long-term hazard if it were to contaminate the worker's skin, and which presents the greater short-term hazard if the worker were only irradiated by it from a distance. Justify your answer.

> OCR A-Level Physics B: Advancing Physics (H557) — 6.2 Electric and magnetic fields · Explain · 5 marks

> Radioactive contamination occurs when radioactive atoms are unwantedly deposited on a material, whereas irradiation is when an object is simply exposed to radiation from a source without the source touching it.

## Mark scheme (5 marks)

1. Isotope P (alpha emitter) presents the greater long-term hazard if it contaminates the skin
2. Because alpha particles are the most ionising, so cause the most damage to cells/tissue when the source is in direct contact with the skin
3. The long half-life of Isotope P means it remains strongly radioactive / continues to irradiate the skin for a long period of time
4. Isotope Q (beta emitter) presents less of a long-term hazard because its short half-life means its activity / radioactivity quickly dies down
5. Isotope Q (beta emitter) presents the greater short-term hazard from irradiation at a distance because beta radiation is more penetrating than alpha and can reach and ionise the worker's body tissues from a distance

## Key terms

- [half-life](https://www.gradenine.co.uk/glossary/half-life)

## Related

- [Revision notes for OCR A-Level Physics B: Advancing Physics (H557)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-worker-at-a-nuclear-waste-26b818f9) · Published by Druglandscape Ltd.