Uses of radioactive material
Tracers: the ability of detectors to measure small quantities of radioactive materials is made use of in tracer applications. Tracers are widely used in medicine, industry and agriculture.
Penetrating radiation: gamma rays are used to penetrate deep into weldings to detect faults. They also photograph the inside of an engine to detect any cracks. Radioactive
sources are also used to check the thickness of steel plates. Gamma rays are also used to sterilise pre-packages food.
Power sources: uranium is used as a fuel in nuclear power stations. Satellites rely on radioactive decay as their power source in space. Some fire alarms contain alpha emitting substances which keep the surrounding air a little ionised and detects any change to the ionisation levels e.g. smoke.
Medical treatment: proper shielded gamma rays can be brought to bear on deep cancerous growth. The radiation kills the cells of the tumour in the patients. These machines are called gammatrons and are used in radiotherapy.
Archaeological dating: radioactive carbon is found in the atmosphere and plants that absorb this carbon dioxide become slightly radioactive. This enables the levels of radioactivity of plants over time to be monitored. Because radioactive substances decay at a rate that we can determine.
Hazards of radiation
Overexposure to radiation may cause radiation burns. Extreme exposure to radiation can cause radiation sickness and in some cases be fatal. Precautions:
i. workers need to wear film badges to monitor the amount that they are exposed to over time; ii. the walls of rooms where radioactive substances are stores must be of lead bricks and over 1m thick. The rooms must be labelled ‘radioactive material’; iii. During an on-going experiment involving radioactive material, the radiation material must be displayed; iv. People working with radioactive substances must wear protective clothing and not touch any substances directly; v. During interaction with radioactive substances food and drink is prohibited.
Background Radiation
The air is radioactive; it contains a radioactive gas called radon, which originates from uranium rocks underground. The ground also contains radioactive substances. Food and drink is also contaminated. Radiation also enters the earth from space in the form of cosmic rays. Most of the radiation is stopped by the earth’s atmosphere. Radiation is also produced by performing X-rays.
Dating
When a living organism dies, the carbon- 14 in its body decays. As time passes, the amount remaining decreases. By measuring the amount remaining, we can work out when the organism was alive. There are two ways to measure the amount of carbon- 14 present in an object:
By measuring the activity of a sample using a detector such as the Geiger counter.
By counting the number of carbon- 14 atoms using a mass spectrometer.