Unit 4 - Lesson 14: Uses of Nuclear Radiation & Risks of Nuclear Radiation Flashcards
What are the medical uses of nuclear radiation?
(Hint: What kind of radiation can cause cancer but also help treat it? What kinds of radiation are released in the body during radiotherapy?)
Gamma rays can cause cancer, but they can also be used to treat it.
Radiotherapy directs a high dose of gamma rays at the cancerous cells.
There is no need for surgery.
Healthy cells can be killed too. Chemicals are added to reduce this.
Alpha and beta radiation is released in the body during radiotherapy, but both have a short range.
Although this isn’t ideal, the alpha and beta radiation is not prolonged and is a price to pay for cancer removal.
How can diseases be diagnosed using nuclear radiation?
(Hint: How can radioactive isotopes be consumed? What is used to trace a radioactive isotope’s path through the body? What radioactive isotope is used to detect diseases of the thyroid? Why are alpha particles poor choices for a tracer?)
Radioactive isotopes can be injected or swallowed.
Their path through the body is traced using detectors.
For this reason, they’re called tracers.
Anything abnormal can be viewed on a computer screen. 3D medical images can also be obtained in this way.
Different tracers are used for different body parts and diseases.
Iodine-123 detects diseases of the thyroid.
Medical tracers always emit beta or gamma radiation because they need to penetrate the body to be detected.
Alpha particles are poor choices for a tracer because they cannot penetrate the body and they are more harmful than gamma and beta when inside the body. They do damage in a small area as they cannot move.
A commonly used isotope in medicine is technetium-99m. It’s a product of molybdenum-99 decaying and releasing gamma rays.
How can nuclear radiation be used to sterilise equipment?
Gamma rays kill bacteria. A high-dose is used to sterilise medical equipment and food of bacteria. It prevents the bacteria rotting fruit (increasing shelf-life), but it doesn’t remove any poison the bacteria previously released. The radioactive source is strong with a fairly long half-life, so doesn’t need to be replaced often.
Sterilisation by gamma rays is called IRRADIATION. Irradiation is the exposure of something to radiation. It can have good consequences for humans, or bad. This is different to contamination, where the radioactive material itself is in contact. For example, injecting the strawberry with a radioactive isotope is contamination.
Irradiation is safe. Contamination is not. It makes things radioactive.
How can nuclear radiation be used to detect faults and leaks?
Gamma rays can be directed through metal parts. A gamma camera will detect the radiation that passes through. Leaking underground pipes (or pipes in power plants) can also be detected in this way.
The isotope is poured into the pipe and a Geiger tube above ground detects. Gamma or beta radiation is used to penetrate rock directly above the pipe.
How can nuclear radiation be used to gauge flow and thickness?
The thickness of materials can be gauged using radiation. This is commonly used in the manufacturing of paper, plastic sheeting and films. As the sheet is made, its thickness is monitored. The half-life of the radiation source should be short, so it doesn’t create a long-term hazard.
How can nuclear radiation be used to measure the contents of containers?
Sewage is sometimes disposed of in the sea. Its thickness is monitored so it doesn’t get too high and damage the environment too much. It’s convenient (and therefore more profitable) to have computers recognise when large industrial containers (hoppers) are full.
Radiation is passed through the container. As it fills, the amount of radiation detected decreases. Gamma rays are ideally used to penetrate the material. However, this may change depending on the contents.
REVISION SHEET 2: RISKS OF NUCLEAR RADIATION
REVISION SHEET 2: RISKS OF NUCLEAR RADIATION
What is exposure to radiation called?
Exposure to radiation is called irradiation.
Is exposure to beta and gamma radiation to the outside of the body dangerous? Explain the dangers from low level exposures and high level exposures.
Yes. It’s very dangerous. They pass through the body, damaging cells as they go. Low level exposures causes damage to molecules like DNA. This results in faulty cells, which can grow cancerous.
High level exposure can kill cells immediately. This can result in radiation sickness.
Is alpha radiation less or more dangerous (than beta and gamma radiation) when exposed from outside the body? Why?
Alpha radiation is not as dangerous when exposed from outside the body because it cannot penetrate the skin. Once inside the body, it can cause cancer as it can’t escape and the ionising power is concentrated in a small area.
Where does exposure come from?
High level exposure can come from nuclear power plant catastrophes such as Chernobyl.
Exposure can come from contaminated objects. Objects become contaminated if radioactive atoms get into them. If you touch the contaminated object, you will be contaminated. If the half-life of the source is long, the object will be contaminated for a long time.
Cigarettes contain radon, which emits alpha particles. This is one of the reasons it causes cancer.
We are always subjected to a very low-level background radiation. Real problems occur when the levels get too high and too prolonged.
Cigarettes contain radon. What does radon emit?
Radon emits alpha particles; this is one of the reasons why smoking causes cancer.
How can we be safe when handling radioactive sources?
All radioactive sources should be handled with care. Wear gloves and use tongs to hold. Sources shown in schools are weak, but they still should be kept in well labelled lead lined boxes.
Sources in nuclear power plants are much stronger. Workers need protective suits and masks.
Workers wear badges matched to the level of exposure they come into contact with. Badges either have a photographic film coating, which goes foggy in response to radiation or are thermoluminescence, which give off light in response to heat.
How can we dispose low-level sources and high-level sources?
Low-level sources can be disposed of in secure landfill sites.
High-level sources, such as spent uranium rods, are first placed in water until their neutron radiation drops. Then they’re (alongside other waste) placed in a glass box inside a metal canister. This is buried deep underground in a location that isn’t prone to earthquakes or volcanoes. If the box was to leak, radiation could contaminate the environment and drinking water.
