Glossary of Terms

alpha

A positively charged particle that consists of two protons and two neutrons bound together. It is emitted by an atomic nucleus undergoing radioactive decay and is identical to the nucleus of a helium atom. Because of their relatively large mass, alpha particles are the slowest and least penetrating forms of radiation. They can be stopped by a piece of paper.

B

baseload electricity

The amount of electricity required to provide stable, day to day electrical needs for a utilities' customers basic needs that is not used in response to weather conditions (ie: heating and cooling).

beta

Beta particles are given off naturally by decaying neutrons in radioactive atoms and can be created in particle accelerators. Beta particles have greater speed and penetrating power than alpha particles but can be stopped by a sheet of aluminum that is 2 to 3 mm thick.

BWR

Acronym for boiling water reactor. Steam, produced from boiling water in contact with the reactor core, drives turbines to generate electricity.

C

calandria

A cylindrical vessel through which vertical tubes pass, forming part of an evaporator, heat exchanger, or nuclear reactor.

CANDU

Acronym for CANada Deuterium Uranium reactor, a Canadian-invented, pressurized heavy water reactor.

cascades

In uranium enrichment processes, groups of centrifuges that are connected together. UF6 is fed progressively through the cascades to enrich the concentration of U235.

centrifugal force

Describes the tendancy of heavier objects that are travelling in a circle to fly away from the center of curvature.

chain reaction

A process in which the result of one event triggers another event, usually of the same kind, which in turn triggers yet another event, so that the overall reaction tends to be self-sustaining. Nuclear fission reactions are chain reactions.

chemical precipitation

The formation of a separable solid substance from a solution, either by converting the substance into an insoluble form or by changing the composition of the solvent.

conglomerates

In geology, a rock consisting of fragments of other rock and minerals that have become cemeted together through sedimentary processes.

control rods

Rods or tubes containing a neutron absorber, such as boron, that can be inserted into or retracted from the core of a nuclear reactor in order to control its rate of reaction.

conversion

A chemical process to convert UO3 from a refinery into UF6 (uranium hexafluoride) as feedstock for enriched light water reactor fuel or UO2 (uranium dioxide) for heavy water CANDU reactor fuel.

coolant

A fluid or gas used to cool a system or to transfer heat from one part of it to another.

core

The central part of a nuclear reactor where atomic fission occurs.

critical mass

The smallest mass of a fissionable material that will sustain a nuclear chain reaction.

D

decay

As it relates to nuclear science, the spontaneous transformation of an unstable atomic nucleus into into a lighter one, during which radiation is released in the form of alpha, beta and other particles and gamma rays.

deconvert

Processing of depleted uranium, or DUF6, to separate fluorine-based compounds from residual uranium, primarily U238.

denitration

One of the steps in the uranium refining process. Concentrated uranyl hexahydrate is thermally decomposed to uranium trioxide (UO3).

digestion

One of the steps in the uranium refining process. Nitric acid is added to uranium concentrates which produces a uranyl nitrate solution.

dosimeter

A device that measures exposure to ionizing radiation.

DUF6

An acronym for depleted UF6 created as tailings from enrichment processes.

E

effluent

In an industrial setting, typically refers wastewater – treated or untreated – that flows out of a treatment plant, sewer, or industrial outfall into surface waters.

electromagnetic waves

Waves of energy travelling through space etc, eg light waves, X-rays, radio waves.

electron

A stable elementary particle with a negative charge.

element

A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus.

emissions

In an industrial setting, typically refers to release of airborn pollutants and greenhouse gasses.

enrichment

The process of increasing the proportion of U235 istotopes from natural levels of 0.7% to 3%-5% for use in light water reactors. Enrichment for the purpose of creating nuclear weapons would require an increase in levels to about 90% U2

F

feedstock

The raw material to supply the beginning of one of the stages in the nuclear fuel cycle. For example, U3O8 is the feedstock for refinement, while the product of that stage, UO3, is the feedstock for UF6 production.

fissile

Material that is capable of sustaining a chain reaction of nuclear fission. Fissile materials can be used to fuel nuclear reactors.

G

gamma

Gamma rays are streams of high-energy electromagnetic radiation given off by an atomic nucleus undergoing radioactive decay. Because the wavelengths of gamma rays are shorter than those of x-rays, gamma rays have greater energy and penetrating power than x-rays.

gamma-ray spectrometry

Measurement of the distribution of the intensity of gamma radiation.

geiger counter

An electronic instrument that detects and measures nuclear radiation.

generator

A machine that converts mechanical energy into electrical energy.

geochemical

Relating to the study of the chemical composition and distribution of elements and isotopes in rocks, soil, sediments, water, and vegetation.

geophysical

Relating to geophysical sciences, the study of the physical properties of rocks and minerals.

graphitic

Relating to graphite, or graphite-like mineral deposits.

gray (Gy)

Measurement unit for the energy absorbed from ionizing radiation, equal to one joule per kilogram.

greenhouse gas

Typically refers to carbon dioxide that contributes to global warming. Also referred to as GHG.

H

half-life

The average time needed for half the nuclei in a sample of a radioactive substance to undergo radioactive decay. The half-life of a substance does not equal half of its full duration of radioactivity. For example, if one starts with 100 grams of radium 229, whose half-life is 4 minutes, then after 4 minutes only 50 grams of radium will be left in the sample, after 8 minutes 25 grams will be left, after 12 minutes 12.5 grams will be left, and so on.

heavy water

Heavy water is virtually identical to H20, except each of the hydrogen atoms have an extra neutron. This hydrogen isotope is called deuterium (D). Since heavy water (D2O) has extra neutrons, it can slow neutrons in the reactor without significantly absorbing them.

heavy water reactors

Nuclear power reactors using unenriched natural uranium as fuel, that use heavy water (deuterium oxide U2O) as a coolant and moderator.

I

ionizing radiation

Ionizing radiation contains enough enegy to change the number of electrons within an atom with which it interacts, changing the composition of the original atom.

isotopes

Isotopes are variants of a particular chemical element. All isotopes of a given element share the same number of protons, but each isotope has a different number of neutrons in its nucleus.

L

light water reactors

Nuclear power reactors that require enriched uranium (between 3%-5% U235) and use normal water as a coolant and moderator.

long-term contracts

Relating to the nuclear fuel cycle, these are multi-year commitments to deliver set quantities of uranium products or services, at negotiated prices, to power plant operators.

M

mass

At the atomic level, mass refers to the total number of protons and neutrons in the nucleus of an atom.

megawatt

A measurement of power, one megawatt is equal to one million (106) watts.

mill tailings

Waste materials from milling processes.

milling

Chemical processing of uranium bearing ore (usually in a water slurry) to extract and concentrate U3O8 or yellowcake.

Million electron volts (Mev)

Electron volt is a unit used to measure the energy of subatomic particles. One electron volt is defined as the energy needed to move an electron across an electric potential of one volt. MeV is an acronym for one million electron volts.

milliSievert (mSv)

1/1000 of a Sievert. A Sievert is the name used to express the measurement of potential harm from radiation exposure.

moderator

A substance, such as water or graphite, that is used in a nuclear reactor to decrease the speed of fast neutrons and increase the likelihood of fission.

mohs

A scale used to measure the relative hardness of a mineral. From softest to hardest, talc measures 1 and diamonds measure 10 on the scale.

N

neutron

An electrically neutral subatomic particle. In radioactive atoms, excess neutrons are converted to protons by beta decay. Beams of neutrons from nuclear reactors are used to bombard the atoms of various elements to produce fission and other nuclear reactions.

non-ionising radiation

Non-ionizing radiation does not affect the nucleus of atoms with which it interacts.

non-proliferation

Relating to, or calling for an end to the acquisition of nuclear weapons by additional nations.

nuclear

Concerned with, or involving the nucleus of an atom.

O

oxide

A compound of an element with oxygen.

P

plutonium

Atomic number 94, it is a naturally radioactive, silvery, metallic element, occurring in uranium ores and produced artificially by neutron bombardment of uranium. Its longest-lived isotope is Pu 244 with a half-life of 80 million years.

proton

A stable subatomic particle with a positive charge equal to the negative charge of an electron.

PWR

Acronym for pressurized water reactor. Water in the core is pressurized enough to remain as a liquid up to temperatures as high as 315 degrees celsuis (600 F). These reactors maintain 3 separated water circulation loops for transfer of heat. The second loop is converted to steam to drive turbines.

R

radiation

The emission and propagation of energy in the form of waves, rays or particles.

radio waves

Radio waves are used for the transmission of radio and television signals; the microwaves used in radar and microwave ovens are also radio waves. Many celestial objects, such as pulsars, emit radio waves.

radioactive

To emit radiation in the form of waves, gamma rays or alpha/beta particles.

radioisotopes

An istotope that is radioactive.

radionuclides

A radioactive atomic nucleus, or radioactive isotope

radon progeny

Radioactive decay products of radon that turn into longer-lived lead isotopes upon decaying such as bismuth 214 (radium C), lead-214 (radium B), polonium-214, and polonium-218 (radium A). These radioisotopes attach themselves to airborne particles and can damage the lung-lining on inhalation. Also called radon daughters.

reduction atmosphere

A reduction atmosphere occurs when the amount of available oxygen is reduced in a firing kiln. When there is a lack of oxygen, the fuel does not burn completely and the kiln atmosphere becomes filled with free carbon. The free carbon atoms aggressively grab up any oxygen atoms they can find.

refining

Further processing of yellowcake from the mill to remove impurities and chemical conversion to UO3 (uranium trioxide), the feedstock for the next stage of processing.

S

sampling

Taking a sample of rock, typically with a sampling drill, for further testing to determine its mineral properties.

shielding

A wall or housing of concrete or lead built around a nuclear reactor to prevent the escape of radiation.

Sievert (Sv)

A derived unit used to measure the amount of radiation necessary to produce the same effect on living tissue as one gray of high-penetration x-rays.

sintered

A method used to create solid objects from powders, typically through high temperatures.

solvent extraction

A method for processing materials by using a solvent to separate out various components.

spot market

Relating to the nuclear fuel cycle, spot market purchases are those that call for delivery within one year.

T

tails assay

Relating to enrichment, analysis of tailings to assess quantities of residual uranium isotopes U235 and U238.

targeting

The process of determining a location with likely mineral deposits.

U

U235

The only uranium isotope found in nature capable of sustaining a nuclear chain reaction; consists of 92 protons and 143 neutrons. About 0.7% of natural uranium consists of the isotope U235.

U238

The most common uranium isotope found in nature, consisting of 92 protons and 146 neutrons. Over 99% of natural uranium consists of this isotope. It is not fissile.

U3O8

Triuranium octoxide is a compound often referred to as yellowcake. It occurs naturally as the mineral pitchblende.

UF6

Uranium hexafluoride is a compound used in the uranium enrichment process to produce fuel for nuclear reactors.

UO2

Uranium dioxide, is a compound used in heavy water CANDU reactors.

UO3

Uranium trioxide, a compound feedstock for enriched light water reactor fuel.

uranium concentrate

Often referred to as yellowcake, uranium concentrates consist of U3O8

uranium hexafluoride

(UF6) A compound used in the uranium enrichment process to produce fuel for nuclear reactors.

uranium trioxide

(UO3) A compound feedstock for enriched light water reactor fuel.

V

vitrified

The formation of an insoluable, solid waste form that will remain stable for many thousands of years. In the case of spent fuel, the high-level waste is dried and mixed with molten glass that is encased in stainless steel.

Y

yellowcake

The common name for the compound triuranium octoxide (U3O8) because of its usual yellow coloring.

Z

zirconium

Zirconium is a very strong, lightweight metal that is extremely resistant to heat and corrosion. Because it does not absorb neutrons, zirconium alloys are used extensively in nuclear applications.

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