Radiation and Safety

Doses, distance and shielding

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Doses are measured in sieverts; natural background is about 2.4 mSv per year.
• Each half-value layer halves gamma intensity; distance cuts dose as 1/r².
• Internal contamination (alpha emitters, iodine-131) is the most dangerous kind.

Steps

1. Measuring dose
2. A year of background
3. Lead shielding
4. Distance is a shield
5. Grays and sieverts
6. Iodine tablets