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Alpha Radiation
You may notice that alpha radiation doesn’t penetrate barriers easily. In fact, even our skin is enough to stop most alpha radiation. However, ingesting alpha radiation can be very dangerous.
Alexander Litvinenko after being poisoned with alpha radiation.
The poisoning of Alexander Litvinenko
Alexander Litvinenko was an ex-Russian KGB officer (a spy) working for the British Government who suddenly fell ill under suspicious circumstances. Initial symptoms were of poisoning then he lost all his hair and died in hospital three weeks later. An autopsy revealed large amounts of a radioactive material in his system. Also, a suspicious trail of radiation was detected wherever Litvinenko had been in the days before being admitted to hospital. It turned out he had been poisoned with a radioactive alpha source called Polonium. It was used because it is safe for the killers to handle, but is lethal when ingested.
Luminescent radium watch dials
Up until the 1960s, glow-in-the-dark watch dials were made using radium paint. These watch dials were hand painted, and the painters often licked the brushes to get a fine point for precise painting. Ingesting radium caused serious health problems, including cancer of the jaw bone. After a law-suit in the 1920s, radium-dial painters were required to wear protective gear and were properly instructed in how to use the paint safely.
Beta Radiation
Radioactive beta material can be safely stored as long as the walls of the container are made thick enough to prevent radiation from escaping. It can also be used to determine the thickness of Aluminium sheets during manufacture by keeping the number of counts at a constant number.
Nuclear reactors are great for generating power but they also generate a lot of radioactive waste which needs to be disposed of.
Using beta radiation to determine the thickness of Aluminium sheets during manufacture.
Radioactive iodine for treating thyroid cancer
Iodine-131 is a radiopharmaceutical used to treat thyroid cancer. A patient swallows a tablet, and the radioactive iodine accumulates in the thyroid gland in the patient’s neck. The beta radiation kills the cancer cells in the thyroid, but the dose is low enough so as not to harm the healthy cells. The patient remains radioactive for 4-5 days, and needs to stay away from small children and pregnant women.
Gamma Radiation
Gamma radiation is highly penetrative. High levels of gamma radiation can be harmful to humans, and require thick barriers for shielding, such as lead. Some nuclear medicines use small doses of gamma radiation to help diagnose diseases, such as cancer and heart disease. This is called radiation therapy.
Gamma radiation has such a high penetrating power you need a very thick barrier to stop it.
A woman being treated for breast cancer with chemotherapy.
Irradiating mangoes to kill grubs and fruit flies
Many fruits and vegetables are irradiated with gamma radiation before they are transported interstate or overseas. Gamma radiation kills pests and disease that may be living on or inside the fruit to prevent their spread into important agricultural areas. The radiation does not make the fruit radioactive and it is safe to eat.
Further Discussion (Optional):
Australia has discussed the possibility of storing nuclear waste in a remote outback area. What do you think about this idea? What are the issues that would need to be considered before saying yes or no?
Here are some quick links to help you form an opinion:
http://www.independentaustralia.net/2011/politics/australia-open-for-nuclear-sewage-business
http://www.managingnuclearwaste.gov.au
Explore Further
Ask your teacher if your class can go on a free excursion to Australia’s only nuclear research reactor at the Australian Nuclear Science and Technology Organisation (ANSTO) in Sydney. You can also visit them virtually by videoconference. For bookings, call 9717 3090 or email tours@ansto.gov.au
YouTube videos.
1) The alpha radiation you have observed in this experiment, which is actually the nuclei (centres) from Helium atoms, is also used by scientists to investigate the structure of matter. In fact, what an atom really looks like was first discovered using alpha radiation fired at a very thin piece of gold.
Rutherford Gold Foil Experiment – Backstage Science
2) The gold foil experiment above showed that all things (such as gold foil) are mostly empty space! It is only very occasionally that the alpha particles actually hit anything.
People Pretending to be Alpha Particles
3) Normally radiation is invisible, since the particles are so small. A cloud chamber can make the radiation particles become visible. Here is how to build one!
