Home » Thorium nuclear fuel » Glossary

Does thorium have the potential to become an alternative nuclear fuel?


Glossary over Does thorium have the potential to become an alternative nuclear fuel?


Americium is a silvery metal and a completely man-made element whose 6 known isotopes are all radioactive.

Americium-241, the most common isotope, is formed spontaneously by the decay of plutonium-241 and has a half-life of 430 years.



The smallest particle of an element that still conserves the chemical properties of that element. Atoms are composed of electrons, protons, and neutrons. (Source: GreenFacts)


Bioaccumulation is used to describe the increase in concentration of a substance in an organism over time.

Bioaccumulative substances tend to be fat soluble and not to be broken down by the organism. (Source: GreenFacts )


Half life

The term which is used for the time required for the amount of a particular substance to be reduced to one half of its value when the rate of decay is exponential.

Radioactive half-life refers to the decay of radioactive substances. Iodine-131, for instance, has a half-life of 8 days whereas that of Plutonium-239 is more than 23 000 years.

Biological half-life refers to decay by biological processes. Substances with a long biological half-life will tend to accumulate in the body and are, therefore, particularly to be avoided. Substances with a short biological half-life may accumulate if some becomes tightly bound, even if most is cleared from the body rapidly. There is also the possibility of cumulative effects of chemicals which have a short residence time in the body. (Source: GreenFacts)



The act of breathing.

A hazardous substance can enter the body by inhaling an airborne substance or contaminant in the form of gas, fumes mists, vapors, dusts, or aerosols. Once inhaled, contaminants can be deposited in the lungs and/or transported into the blood. (Source: GreenFacts)

Organization for Economic Co-operation and Development

The Organization for Economic Co-operation and Development (OECD) is "an international organisation helping governments tackle the economic, social and governance challenges of a globalised economy(... It) groups 30 member countries sharing a commitment to democratic government and the market economy."

See their Environment Pages:


Plutonium is a heavy, man-made, radioactive metallic element. The most important isotope is Pu-239, which has a half-life of 24 000 years. Pu-239 can be used in reactor fuel and is the primary isotope in nuclear weapons.

In the context of Chernobyl, an important radioisotope of Plutonium is Pu-241, which has a half-life of 14.4 years and decays into americium-241.



Energy moving in the form of particles or waves. Familiar radiations are heat, light, radio waves, and microwaves. Ionizing radiation is a very high-energy form of electromagnetic radiation. (Source: US Center for Disease Control and Prevention Glossary of Radiological Terms   )


Radioactive material

Material that contains unstable (radioactive) atoms that give off [ionizing] radiation as they decay. (Source: CDC Glossary of Radiological Terms   )

Radioactive waste

Any waste that emits energy as rays, waves, streams or energetic particles.

Radioactive materials are often mixed with hazardous waste, from nuclear reactors, research institutions, or hospitals. (Source: US EPA Terms of Environment  )



The spontaneous emission of ionizing radiation from the nucleus of an unstable atom. Radioisotopes lose particles and energy through this process. (Source: GreenFacts, based on Energy Information Administration Glossary   )



A radioactive gas that is released by the breakdown of uranium, a substance found in some soils and rocks. It can get inside buildings by diffusing through the soil and can also be released from concrete.

Breathing in too much radon can damage lung cells and lead to lung cancer. (Source: GreenFacts )


A characteristic or state whereby the needs of the present and local population can be met without compromising the ability of future generations or populations in other locations to meet their needs.



When the combined effect of several forces operating is greater than the sum of the separate effects of the forces. (Source: Millennium Ecosystem Assessment  Glossary )


Naturally occurring heavy metal that is denser than lead.

Uranium is radioactive and is the principal fuel of nuclear reactors. (Source: GreenFacts )

Other articles you might like...
Tidal Energy home
What is the potential or this energy source?
Geothermal Energy home
What is the place of geothermal energy in the energy mix?
Biochar home
Biochar can be used as fuel or as a fertilizer, and is particularly relevant to developing countries.
A-Z List
Themes covered
Publications A-Z

Get involved!

This summary is free and ad-free, as is all of our content. You can help us remain free and independant as well as to develop new ways to communicate science by becoming a Patron!