Radioactive substances can be useful. In fact, some of them are used in fields like medicine, agriculture and archaelogy.
- In the medical field, the radioactive iodine-131, whose pathway can be traced, is injected into patients with thyroid gland dysfunction to check the function of the glands and detect the growth of tumours.
- To trace water leakages underground, radioactive substances are introduced into water pipelines. When there is a water leakage, radioactive detectors such as Geiger-Muller counter will provide radioactive readings.
- Gamma rays are used to sterilise medical instruments to prevent contamination. In the food industry, they are used to prevent decay of food so that the food can last longer and be exported. In agricultural field, gamma rays are used to sterilise pests.
- In a nuclear reactor, radioactive substances decay and give out a great amount of energy, which is used as an electrical energy source. However, this type of energy is expensive.
- Nuclear energy is derived from the nucleus of a substance. Nuclear energy can be produced by fusion (joining two nuclei of atoms to form a heavier nucleus) or fission (splitting the nucleus into two smaller and lighter nuclei, and releasing one or more neutrons).