Glossary

A | B | C | D | E | F | G | H | I | K | L | M | N | P | R | S | T | U | V | X | Y

A
A-bomb
Absorbed Dose (of ionizing radiation): The amount of ionizing radiation energy absorbed in a given mass of human tissue. The unit of measurement for the absorbed dose is the gray (Gy) which is equal to one Joule per kilogram (J/kg).
Acid ISL: Extracting a mineral without digging it up by pumping an acid solution into the ground. A common solution is sulphuric acid in water.
Acid Leaching: Extracting a mineral by using an acid solution. A common solution is sulphuric acid in water.
Activity (of a radioactive isotope)
Alkaline ISL: Extracting a mineral without digging it up (in situ) by pumping an alkaline solution into the ground. A common solution is sodium bicarbonate in water.
Alpha Emitter: A radioactive isotope that emits an alpha particle during radioactive decay.
Alpha Particle: A positively charged particle containing two protons and two neutrons (the nucleus of a helium atom).
Alpha Radiation: A form of ionizing radiation consisting of alpha particles. Alpha particles/radiation are emitted during radioactive decay of certain radioactive isotopes including isotopes of uranium, plutonium, polonium, thorium, and radon. Because of its mass and charge, alpha radiation is very damaging to living cells.
Americium (Am)
Aquifer: An underground water system.
Atom: The smallest unit of a chemical element made up of a nucleus containing protons and neutrons, and electrons which surround the nucleus.
Atomic Number: Number of protons in the nucleus of an atom.
B
Background (Ionizing) Radiation: Ionizing radiation that we are exposed to in our everyday lives. Background radiation now includes radiation which is a result of nuclear power and nuclear weapons activities. It also includes cosmic radiation, ionizing radiation from soils and rocks, and radon gas that emanates from the ground.
Becquerel (Bq): The unit of measurement of radioactivity. One Bq is one radioactive disintegration per second. Radioactivity was previously measured in Curies. One Curie is 3.7x10¹⁰ Bq.
Beta Emitter: A radioactive isotope that emits a beta particle during radioactive decay.
Beta Particle: An electron or positron.
Beta Radiation: A form of ionizing radiation made up of very fast, high energy, electrons or positrons. Beta particles/radiation are emitted during the radioactive decay of certain radioactive isotopes.
C
Carcinogenic: Capable of causing cancer. Ionizing radiation is carcinogenic.
Chain Reaction: A nuclear reaction which is self-sustaining.
Conversion (of uranium): Changing solid uranium oxide into gaseous uranium hexafluoride (UF₆).
Cyclotron
D
Decay Product: The product of the radioactive decay of a radioactive isotope. The products may themselves br radioactive and decay to other radioactive isotopes.
Depleted Uranium: One of the by-products of uranium enrichment. Depleted uranium has a lower concentration of the isotope U235 and a higher concentration of the isotope U238. Depending on the source of the uranium, DU may contain significant amounts of other radioactive isotopes, many of which have much higher specific activity than U-235 and U-238.
Dose Equivalent (of ionizing radiation): The amount of ionizing radiation energy absorbed in a given mass of human tissue multiplied by a factor (the quality factor) that takes into account the type of ionizing radiation absorbed. The unit of measurement of the dose equivalent is the sievert (Sv).
E
Ecologically Sustainable: Being able to meet current and future needs without irreversibly damaging the ecosystem.
Ecosystem: An interacting, interdependent community of living organisms.
Electromagnetic Radiation: Radiation involving the interaction between electric and magnetic fields. It may be ionizing or non-ionizing.
Electron: A negatively charged particle present in every atom. Electrons surround the positively charged nucleus of an atom.
Element
Energy: The ability to do work. There are various forms of energy e.g. heat, light, electrical, etc., which may be interconverted.
Enhanced Greenhouse Effect: Increase in the natural ability of a layer of certain gases to trap heat within the earths atmosphere. The effect is viewed with concern because of its ability to cause significant climate change.
Enriched Uranium: One of the products of uranium enrichment. Enriched uranium has a higher concentration of the isotope U-235 and a lower concentration of the isotope U-238.
F
Fissile: Able to be split.
Fissile Isotope
Fission (nuclear): The splitting of the nucleus of an atom. It can be spontaneous or artificially induced. Nuclear fission of heavy elements such as uranium and plutonium releases energy and ionizing radiation. It is the process used in nuclear reactors and nuclear weapons.
Fossil Fuel: Fuel formed in the earths crust from the remains of biomass , e.g.. oil, coal, natural gas.
Fusion (nuclear): The merging, or fusing together, of atomic nuclei. Fusion of the nuclei of light elements such as hydrogen (H) and lithium (Li) produces energy and ionizing radiation.
G
Gamma Emitter: A radioactive isotope that emits gamma radiation during radioactive decay.
Gamma Radiation: A high energy form of ionizing radiation similar to X-rays emitted when a radioactive isotope decays from a high energy state to a lower energy state.
Greenhouse Gas: A gas which contributes to the enhanced greenhouse effect.
H
Half Life: The length of time that it takes, on the average, for half of the nuclei of a given radioactive isotope to decay.
H-bomb: Hydrogen bomb. A nuclear fusion weapon using uranium explosive to fuse nuclei of light elements such as hydrogen and lithium.
High Level Radioactive Waste: Waste containing high levels of beta and gamma and beta ionizing radiation emitters and significant levels of alpha ionizing radiation emitters, and generating significant amounts of heat. This is the definition given by the nuclear industry. It is misleading because heat generation is from fissile isotopes that contribute very little to the radioactivity of the waste.
Highly Enriched Uranium (HEU)
I
Intermediate Level Radioactive Waste: Waste containing high levels of beta and gamma and beta ionizing radiation emitters and significant levels of alpha ionizing radiation emitters. This is the definition given by the nuclear industry. It is misleading because it has the same amount of radioactivity as high level radioactive waste but does not generate heat because the concentration of low radioactivity fissile isotopes has been reduced.
Ion: A charged atomic sized particle. Ions may be negatively or positively charged.
Ionizing Radiation: Radiation which is sufficiently energetic to convert neutral particles, such as atoms and molecules, into charged particles (ions).
Irradiation: The process of exposing something or someone to ionizing radiation.
ISL (In Situ Leaching): Extracting a mineral without digging it up by pumping solution into the ground.
Isotope: Atoms of an element with the same number of protons but differing numbers of neutrons. Each particular isotope of an element has the same number of protons and neutrons.
K
Kinetic energy: The energy possessed by a moving body by virtue of its mass and velocity.
L
Low Level Radioactive Waste: Waste containing short lived beta and gamma ionizing radiation emitters and alpha ionizing radiation emitters.
Low Level Radioactive Waste Repository: The Australian Government's term for a shallow burial site in which it intends burying both low level radioactive waste and short lived intermediate level radioactive waste. The Australian Government defines this material as "low level radioactive waste" whereas the International Atomic Energy Agency (IAEA) defines it as "low and intermediate level radioactive waste".
M
Mass Number
Maximum Allowable Dose: The maximum annual dose equivalent (in sieverts) of ionizing radiation that may be received by a person as a result of some nuclear industry activity. The limit is determined on the basis of what is considered to be an acceptable health risk for the average person. The maximum allowable dose is determined by law. It is 20 mSv for workers in the nuclear industry and 1 mSv for the general public. This limit is over and above the background radiation dose.
Molecule
MOx (Mixed Oxide)
Mutagenic: Capable of forming birth defects. Ionizing radiation and heavy metals such as uranium and plutonium are mutagenic.
N
Neutron: An uncharged sub-atomic particle. Found in the nucleus of every atom except ordinary atomic hydrogen (H). Neutrons are an extremely harmful form of ionizing radiation emitted during operation of a nuclear reactor or by a nuclear explosion.
Non-renewable: Resources which will be exhausted in human (as opposed to geological) time.
Nuclear reactor: A device in which a nuclear fission reaction is maintained and controlled for the purpose of either generating heat, radioactive isotopes, or ionizing radiation such as neutrons.
Nuclear Weapon: An explosive device using uranium, or uranium and plutonium.
Nucleus (of an atom)
Nuclide: Atoms of an element in which the nuclei are in different energy states. The lowest energy (ground) state is the most common energy state. Higher energy (excited) states are generally unstable and have short lives. A metastable state is a long-lived excited state. An isotope may have several nuclides, e.g. a low energy nuclide and a high energy metastable nuclide, e.g.., Am-251 and Am-251m.
P
Plutonium (Pu): An artificial element with atomic number 94 produced during the fission of uranium. Plutonium is highly toxic and radioactive. The radioactive isotope Pu-239 produced from U-238 is an alpha emitter with a half life of 24,360 years. Pu-239 is fissile and is the favoured material for nuclear weapons.
Polonium (Po): An radioactive element with atomic number 84 found in uranium ore.
Positron: A particle with the same mass as an electron but with a positive, rather than a negative, charge.
Proliferation (of nuclear weapons)
Proton: A positively charged particle found in the nucleus of all atoms.
Pyrophoric
Q
Quality Factor: A factor that measures the relative damage done by various types of ionizing radiation. The most damaging ionizing radiation is alpha radiation, which has a quality factor of 20. This compares with X-rays, electrons and gamma ionizing radiation, which have a quality factor of 1. A given dose of alpha ionizing radiation is therefore 20 times more damaging to human tissue than the same dose of gamma radiation or X-rays.
R
Radiation: The emission or transfer of energy as particles or electromagnetic waves.
Radioactive Decay: The spontaneous breakdown of radioactive isotopes with the emission of ionizing radiation.
Radioactivity: The emission of ionizing radiation by radioactive isotopes as they decay.
Radioisotope: A radioactive isotope.
Radiolysis
Radiolytic Products
Radionuclide: A radioactive nuclide.
Radium (Ra): A radioactive element with atomic number 88 found in uranium ores. The predominant isotope of radium is radium-226, which originated by radioactive decay from uranium-238 via radioactive thorium. Radium-226 is an alpha emitter with a half life of 1.622 years.

Radon (Rn)
Renewable: Resources which are constantly being renewed (such as biomass) or which cannot be exhausted in human (as opposed to geological) time (such as sun, wind, waves).
Repository: A shallow burial site. More commonly referred to as a dump.
Reprocessing (of spent nuclear fuel): The process of removing uranium and plutonium from spent nuclear fuel.
S
Short-lived Radioactive Waste: Radioactive waste containing isotopes with a half life less than 30 years.
Short-lived Radioisotopes: Radioactive isotopes with a half life less than a week.
Sievert (Sv): A measure of the biological damage to a person caused by ionizing radiation. It is determined by the amount of energy absorbed and the type of ionizing radiation. The more Sv of ionizing radiation which one receives the greater the health risk.

Slurry: A fluid mixture of liquids and solids.
Specific Activity
Spent (nuclear) Fuel: Nuclear reactor fuel in which the amount of fissile material has decreased to levels that are insufficient to operate the reactor.
Sustainable: That which can be sustained.
T
Tailings: Waste in the form slurry from the processing of ore. Frequently containing toxic and (in the case of uranium ore) radioactive substances.
Toxic: Poisonous.
U
Uranium (U): A radioactive, pyrophoric, silvery-white metallic element with atomic number 92. Uranium reacts rapidly with air. Uranium powder spontaneously combusts in air to give finely divided radioactive uranium oxides. The main isotopes of uranium found in ore bodies are uranium-238 (99.7%) and uranium-235 (0.3%). Uranium-238 is an alpha emitter that decays with a half life of 713 million years to radioactive isotopes of thorium, radium, radon, polonium and lead. All of these radioactive isotopes are found associated with uranium mining and processing where they end up in the tailings.
Uranium Depletion: The process of decreasing the concentration of the fissile isotope U235 in a mixture of uranium isotopes.
Uranium Enrichment: The process of increasing the concentration of the fissile isotope U235 in a mixture of uranium isotopes. For nuclear reactors the increase is typically from 0.7% to 3%. For nuclear weapons the increase is much larger. The resultant mixture has a lower concentration of U238.
V
Vitrification: A process where radioactive waste is encapsulated in glass.
X
X-rays
Y
Yellowcake: The name originally given to the bright yellow substance ammonium diuranate, now applied to a mixture of uranium oxides , which may be yellow or dark green in colour. Uranium is processed into yellowcake at the Roxby Downs, Beverley, and Honeymoon uranium mines..

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