Radiation safety rests on three controls: limit the time near a source, keep your distance and use shielding. A good exam answer names the control, links it to the type of radiation and gives a reason.
This lesson is part of nuclear energy. It uses the shielding ideas from distinguishing radiation types.
What are the three controls?
Every source-handling rule can be sorted into one of the three controls below.
| Control | What to do | Why it works |
|---|---|---|
| Time | Spend as little time near the source as possible | Less time means less radiation absorbed |
| Distance | Keep as far away as possible, use tongs | Radiation weakens with distance |
| Shielding | Put lead, concrete or thick barriers between you and the source | Material absorbs the radiation |
Match the shielding material to the radiation. Paper stops alpha, aluminium stops beta, and thick lead or concrete reduces gamma.
Worked example: a school store
Question: A radioactive source is kept in a school store. Suggest three safety measures and explain each.
Measure 1: shielding. Keep the source in a thick lead-lined container. Lead absorbs most of the gamma radiation, so less reaches people.
Measure 2: distance. Handle the source with long tongs, never with bare hands. Distance reduces the radiation that reaches the body.
Measure 3: time. Take the source out only for the time needed and put it back at once. A shorter time means a smaller dose.
Each measure names the action and the reason, which earns two marks rather than one.
How are reactors and waste controlled?
Safety in a power station uses the same ideas on a larger scale. The reactor is surrounded by thick shielding. Control rods can slow the reaction. Workers use badges that record how much radiation they have received.
Used fuel is stored in sealed, shielded containers. Because the waste stays radioactive for a long time, it is monitored until the activity has dropped. Half-life data explains how long that takes.
The mistake that costs marks
The slip is to write a general safety statement without a reason, such as “be careful” or “wear protective clothing”.
| Wrong | Right |
|---|---|
| Be careful with radiation | Use tongs so the hands stay far from the source |
| Wear a suit | Wear a dosimeter badge so the dose can be measured |
| Store it safely | Store it in a lead-lined box because lead absorbs gamma radiation |
State the control (time, distance or shielding) in the answer. That word anchors the mark.
Check yourself
A worker must spend 30 minutes each day near a gamma source. Suggest two ways to reduce the dose and give a reason for each.
Answer
Use a thick lead or concrete screen between the worker and the source, because these materials absorb gamma radiation.
Work with long tools from a greater distance, because radiation weakens as the distance from the source grows.
A third acceptable point is to rotate workers so each spends less time near the source.
What to study next
This lesson closes the nuclear energy cluster. Test everything in the nuclear energy practice set, and log your slips in the mistake log and paper-error review.
To practise safety questions with a teacher, see online one-to-one Science tuition.