5.2.5Nuclear Physics
Safety Precautions — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions
5 min read 10 parts Lesson 15 of 17 1 quiz
Lesson summary
5.2.5 Safety Precautions — IGCSE PHYSICS notes: Describe the effects of ionising radiation on living things and how radioactive materials are safely moved, used and stored.Ionisation — ionising radiation damages or kills living cells.Mutation — it can cause mutations in DNA, whic…
- High doses
- Gamma and beta
- Principles
- Greater distance
- Food and drink
- Monitoring
Part 1 of 9Effects on living things
Ionisation
- Ionisation ionising radiation damages or kills living cells.
Mutation
- Mutation it can cause mutations in DNA, which can lead to cancer.
High doses
- High doses they cause radiation sickness and burns.
Part 2 of 9Source outside the body (Extended)
Gamma and beta
- Gamma and beta most hazardous, because they can penetrate the skin to reach organs.
Alpha
- Alpha stopped by the dead outer layer of skin.
Part 3 of 9Source inside the body (Extended)
Alpha
- Alpha most hazardous when inhaled or swallowed, because it is strongly ionising and all its energy is deposited in a small volume of tissue.
Gamma and beta
- Gamma and beta less hazardous inside the body.
Part 4 of 9Precautions
Principles
- Principles reduce exposure time, increase distance from the source and use shielding.
Less time
- Less time fewer emissions are received.
Greater distance
- Greater distance the radiation spreads out, and alpha and beta are absorbed by air.
Shielding
- Shielding absorbing materials stop radiation before it reaches the body.
Part 5 of 9Handling sources safely
Tongs
- Tongs handle sources with long tongs (forceps), never with bare hands.
Direction
- Direction point sources away from people.
Food and drink
- Food and drink never eat or drink near sources.
Staff
- Staff medical staff leave the room during X-rays or radiotherapy for the same reasons.
1
Collect the source in its lead-lined container from the locked store and record its removal.
2
Remove it only with long-handled tongs, pointing it away from people.
3
Carry out the experiment quickly, standing as far away as practical.
4
Return the source to its lead-lined container immediately after use.
5
Lock it away, record its return and wash hands.
Part 6 of 9Storage and monitoring
Storage
- Storage keep sources in lead-lined containers in locked cabinets, labelled with the radiation hazard symbol.
Return
- Return put sources back promptly after use.
Monitoring
- Monitoring workers wear dosimeter (film) badges to monitor their exposure.
Protection
- Protection workers may wear protective clothing and work behind lead or concrete screens or use remote handling.
Part 7 of 9Waste
- Radioactive waste
- stored securely, often deep underground or in sealed containers, for times many half-lives long.
Part 8 of 9Summary of precautions
| Precaution | Reduces | Reason |
|---|---|---|
| Increase distance | Dose | Intensity falls with distance |
| Reduce time | Dose | Less exposure |
| Shielding | Dose | Absorbs radiation, for example lead aprons and boxes |
| Safe storage | Exposure | Lead-lined, labelled boxes |
| Monitoring | Overexposure | Dosimeter badges |
Part 9 of 9More from the specification
More from the specification
Magnetic containment and shielding means
- Magnetic containment and shielding means redirecting charged beam trajectories using magnetic fields provides an engineering means to prevent personnel exposure.
Radioactive decay
- Radioactive decay an unstable nucleus emits alpha, beta or gamma radiation randomly, changing its proton and neutron numbers.
Ionising radiation
- Ionising radiation particles that remove electrons from atoms and can damage cells and DNA.
Background radiation
- Background radiation low-level radiation from rocks, cosmic rays and food that must be subtracted from a measured count rate.
Protection
- Protection limit exposure time, increase distance, use shielding such as lead, and store sources in lead-lined containers.
Handling sources
- Handling sources use tongs, never point sources at people, and keep them stored away to reduce risk.
Magnetic field
- Area around a magnet where its effects can be detected.
Decay equation
- An equation in nuclide notation with balanced nucleon and proton numbers.
Kinetic energy
- K = ½mv2, energy of motion.
Radioactive decay
- Radioactive decay an unstable nucleus emits alpha, beta or gamma radiation randomly, changing its proton and neutron numbers.
Ionising radiation
- Ionising radiation particles that remove electrons from atoms and can damage cells and DNA.
Background radiation
- Background radiation low-level radiation from rocks, cosmic rays and food that must be subtracted from a measured count rate.
Protection
- Protection limit exposure time, increase distance, use shielding such as lead, and store sources in lead-lined containers.
Handling sources
- Handling sources use tongs, never point sources at people, and keep them stored away to reduce risk.
Detector
- An instrument that records the particles produced in collisions.
Background radiation
- Radiation that is always present in the environment.
Radioactive decay
- Natural process in which unstable nuclei release energy.
Penetrating power
- How far radiation travels through a material.
Alpha decay
- Loss of 2 protons and 2 neutrons.
Ionising power
- How strongly radiation ionises atoms.
Unstable nucleus
- A nucleus with an imbalance of protons and neutrons that may decay.
Electric field
- Region of space in which a charge experiences a force.
Nucleus
- Small, dense, positively charged centre of the atom.
Neutron
- Neutral particle in the nucleus, relative mass 1.
Proton
- Positive particle in the nucleus, relative charge +1 and relative mass 1.
Charge
- Quantity of electricity in coulombs, Q = It.What the symbols mean: Q = charge (C) · I = current (A) · t = time (s)
Isotope
- Atom of the same element with a different number of neutrons.
Key terms
| Term | Meaning |
|---|---|
| Dosimeter | Badge that records a worker's radiation exposure. |
| Shielding | Material that absorbs radiation. |
| Hazard symbol | Warning sign for radioactivity. |
| Tongs | Long-handled tool for holding a source at a distance. |
| Lead-lined container | Box that stores sources safely. |
Avoid these mistakes
1
Handling sources with bare hands.
2
Saying alpha is harmless — it is the most hazardous inside the body.
3
Thinking one precaution is enough — time, distance and shielding are all used.
4
Forgetting to return sources to their lead-lined containers immediately after use.
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