IGCSE Physics / Applications of radioactivity
Dangers of ionising radiation and radioactive waste
Edexcel International GCSE Physics (4PH1), chapter 24: Applications of radioactivity, specification point 7.16. Free lesson.
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Ionising radiation can damage cells and DNA, increasing the risk of cancer, while a large dose can kill cells and damage tissue. Workers reduce their exposure, and radioactive waste is contained, stored and monitored to reduce its risks.
How ionising radiation damages cells
Radiation passing through a cell can knock electrons out of atoms and molecules. This is ionisation. The resulting ions can damage the cell and its DNA, the instructions inside it. A change in DNA is a mutation. If a mutated cell divides out of control, it may lead to cancer. A large dose can instead kill cells and damage whole tissues, causing radiation sickness. Radiation increases the risk of cancer, but it does not mean that any exposure will cause cancer. Everyone receives a small dose from background radiation. The risk of cancer rises as the dose increases.
How workers reduce their radiation dose
The dose is the amount of radiation a person's body receives. Each precaution reduces the dose by limiting exposure or keeping the source away from the body. Shielding: store sources in lead-lined boxes and work behind lead or thick concrete. Distance: stand as far away as possible. Radiation spreads out and is absorbed by air. Time: spend as little time as possible near a source, and put it away straight after use. Tongs: never touch a source by hand. Use long-handled tongs and hold it at arm's length, pointing it away. Film badges: wear one to record the dose…
What makes radioactive waste a problem
Used fuel from nuclear power stations and some hospital waste stays radioactive. Waste with a very long half-life can remain dangerous for thousands of years, so it must be stored safely for a long time. It may leak into water supplies, and liquid waste can spread easily. People also need to be kept away from it, and problems may appear over time. Waste must be kept in a stable place for as long as it remains radioactive. Leaks could contaminate water supplies. Liquid waste can spread, and storage sites need monitoring for faults or leaks.
How the risks from radioactive waste are reduced
Each waste problem has a matching way to reduce the risk. Vitrification means sealing liquid waste into glass, which does not dissolve or leak. Store long-lasting waste in a stable place for thousands of years. Seal waste in steel and concrete containers to reduce the chance of leaks. Vitrify liquid waste so it cannot spread easily. Bury waste deep underground in rock, far from where people live. Monitor the storage site with detectors to check for leaks.