Radionuclide

Radionuclides, (often referred to by chemists and biologists as Radioactive isotopes or radioisotopes) play an important part in the technologies that provide us with food, water and good health. Radionuclides undergo radioactive decay, during which they give off energy and, or subatomic particles. Radionuclides do occur naturally, but are also artificially produced by bombarding particular elements with neutrons (usually emitted from a nuclear reactor or particle accelerator). Radionuclides are used in two major ways: for their chemical properties and as sources of radiation.

Trace radionuclides are those that occur in tiny amounts in nature either due to inherent rarity, or to half-lives that are significantly shorter than the age of the Earth. Synthetic isotopes are not naturally occurring on Earth, but they can be created by nuclear reactions.

Uses

Radionuclides of familiar elements such as carbon can serve as tracers because they are chemically very similar to the non-radioactive nuclides, so most chemical, biological, and ecological processes treat them in a near identical way. One can then examine the result with a radiation detector, such as a geiger counter, to determine where the atoms one has provided have ended up. For example, one might culture plants in an environment in which the carbon dioxide contained radioactive carbon; then the parts of the plant that had laid down atmospheric carbon would be radioactive.

In medicine, radionuclides are used for diagnosis and research. Radioactive chemical tracers emit gamma rays which provides diagnostic information about a person's anatomy and the functioning of specific organs. Radiotherapy also uses radiation in the treatment of some illnesses, such as cancer. More powerful gamma sources are used to sterilise syringes and other medical equipment. About one in two people in Western countries are likely to experience the benefits of nuclear medicine in their lifetime.

In food preservation, radiation is used to stop the sprouting of root crops after harvesting, to kill parasites and pests, and to control the ripening of stored fruit and vegetables.

In agriculture and animal husbandry, radionuclides also play an important role. They are used to produce high intake of crops, disease and weather resistant varieties of crops, to study how fertilisers and insecticides work, and to improve the production and health of domestic animals.

Industrially, and in mining, radionuclides are used to examine welds, to detect leaks, to study the rate of wear of metals, and for on-stream analysis of a wide range of minerals and fuels.

Most household smoke detectors use radionuclides containing americium formed in nuclear reactors, saving many lives.

Environmentally, radionuclides are used to trace and analyse pollutants, to study the movement of surface water, and to measure water runoffs from rain and snow, as well as the flow rates of streams and rivers.

Natural radionuclides can be used in archaeology and in paleontology to measure ages. When radioactive carbon, for example, is in the atmosphere, it rapidly becomes separated from its decay products. Once it is bound up in a solid, such as wood or paper, its decay products must remain in place. So by measuring how much of these decay products has accumulated, one can estimate the time when the carbon was captured into solid form.

Dangers

If radionuclides are released into the environment, through accident, poor disposal, or other means, they can constitute real or percieved dangers from radioactive contamination.

Radionuclide

Uses

Dangers

See also