5.2.5 Safety precautions
- Syllabus
- 0625–2026–2027
- Topic
- 5.2.5
- Level
- —
Learning objectives
5.2.5.1Effects of ionising nuclear radiations• State the effects of ionising nuclear radiations on living things, including cell death, mutations and cancer5.2.5.2Radioactive materials are moved, used• Describe how radioactive materials are moved, used and stored in a safe way5.2.5.3Safety precautions for all ionising• Explain safety precautions for all ionising radiation in terms of reducing exposure time, increasing distance between source and living tissue and using shielding to absorb radiation
Describe the effects of ionising radiation
Ionising nuclear radiation can remove electrons from atoms and molecules in living tissue. The resulting ions and chemical changes can damage cells.
| Effect | What it means |
|---|---|
| cell death | damage is severe enough that a cell can no longer function or reproduce |
| mutation | radiation changes genetic material in a surviving cell |
| cancer | a mutation may disrupt control of cell division, allowing uncontrolled growth |
Greater exposure increases the chance and extent of biological damage because more ionising interactions can occur in living tissue.
A mutation does not automatically become cancer, and not every exposed cell dies. The required point is that ionising radiation can cause cell death, mutations and cancer.
Move, use and store radioactive materials safely
| Stage | Safe practice |
|---|---|
| move | keep the source in a closed shielded container; use an approved carrier or remote handling method |
| use | remove only when needed; handle with tongs or a manipulator; never touch; keep it directed away from people and return it promptly |
| store | place in a suitable shielded, labelled container inside a secure locked store with controlled access |
Use the smallest suitable source, restrict use to trained people, monitor personal exposure when required and follow a documented procedure for loss, damage or contamination.
A sealed source keeps radioactive material contained, but its radiation can still leave the source. It therefore still needs time, distance and shielding controls.
A fume cupboard, ordinary glass bottle or high shelf is not automatically safe storage. The source must be shielded against its radiation and secured against unauthorised access.
Explain time, distance and shielding precautions
| Precaution | How it reduces dose to living tissue |
|---|---|
| reduce exposure time | less time exposed means fewer emissions can reach and ionise tissue |
| increase distance | radiation spreads out, so less reaches a given area of tissue farther from the source |
| use shielding | suitable material between source and tissue absorbs radiation before it reaches the person |
Prepare the procedure before exposing the source, use tongs to increase distance, work behind a barrier and return the source to its shielded container immediately after use.
Shielding must match the radiation and be thick enough: paper can stop alpha, aluminium can stop beta, while penetrating gamma generally needs thick lead or concrete.
These principles apply to all ionising radiation. A low-penetration source can still be hazardous at close range or if radioactive material enters the body.
Lead does not repel radiation and does not change a source's half-life. It protects by absorbing radiation; time and distance remain important even when shielding is present.