American Nuclear Society

Home / Public Information / Media / Winter Meeting Media Kit / Nuclear Lingo

Nuclear Lingo

Alpha raysIonizing, electromagnetic radiation of low energy and long half-life
AtomThe smallest particle of an element having the chemical properties of that element
Background radiationThe radiation that is always present in the environment and is produced by natural sources such as cosmic rays, radioactive elements in the ground, and the human body
BaseloadThe minimum steady demand for electrical power on the generating system
Beta rays
Boiling water reactor (BWR)A nuclear power reactor cooled and moderated by water where the steam generated in the cooling process is used as to power a turbine which in turn powers a generator that produces electricity
BoronA chemical element that absorbs neutrons, thus controlling or stopping completely a nuclear chain reaction
Breeder reactorA nuclear reactor that produces more fissionable material than it consumes
Capacity factorA universal standard for measuring power plant performance, comparing a plant’s actual output with its maximum potential output, expressed as a percentage
Chain reactionThe process by which atomic fission becomes self-sustaining
ContainmentThe structures designed to prevent the escape of radiation
Control rodsRods made of neutron-absorbing material that are used to regulate or halt fission in a nuclear reactor
CoolantA liquid or gas circulated through the core of a nuclear reactor to extract the heat from both the fission process and decay process, and to provide shielding from radiation
CoreThe central portion of a nuclear reactor containing the fuel rods, moderator and control rods.
CriticalThe term used to describe a nuclear reactor that is sustaining a chain reaction
Critical massThe minimum amount of fissionable material needed to start and continue a chain reaction
DecommissionThe process of closing down and putting into a safe state a nuclear reactor at the end of its useful life
DecontaminationThe removal of radioactive material
ElectronsA negatively charged particle that orbits the nucleus of an atom
FissionThe splitting of atoms when an atom’s nucleus is bombarded by neutrons, which results in the release of large amounts of energy.
Fuel assemblyA group of nuclear fuel elements
Fuel cycleThe sequence of steps involved in supplying, using, reprocessing, and disposing of the fuel used in nuclear reactors (Reprocessing is currently not used in the United States.)
Fuel rodA metal rod containing fissionable material in the form of pellets that is used in a nuclear reactor to produce energy
Gamma raysIonizing, electromagnetic radiation of high energy and short wavelength
Gas-cooled reactorA nuclear reactor in which a gas, such as carbon dioxide or helium, is used as a coolant
Half lifeThe time required for half the atoms of a radioactive substance to disintegrate into another form that is not radioactive
High level wasteMaterial that is still considerably radioactive
Ionizing radiationRadiation such as x-rays that come from the high energy end of the electromagnetic spectrum
Kilowatt hourThe amount of electricity produced in one hour by one kilowatt of capacity or the quantity of power consumed by ten 100-watt light bulbs burning for one hour
Light water reactorA nuclear power reactor cooled and moderated by water
Low level wasteRadioactive material that is only slightly or moderately contaminated
MegawattA standard measure of electrical capacity where one megawatt equals one million watts or a thousand kilowatts
MeltdownA type of nuclear accident in which the fuel becomes so overheated that it melts
MilliremOne one-thousandth of a rem
ModeratorA material used in a nuclear reactor to slow neutrons
NeutronAn uncharged particle found in the nucleus of every atom except hydrogen
NucleusThe core of the atom made up of positively charged protons and neutral neutrons (except Hydrogen, which has only one proton and no neutrons)
Pressurized water reactor (PWR)A light water reactor in which the water used as a moderator is kept under pressure, preventing it from boiling at normal temperatures
ProtonA positively charged particle found in the nucleus of an atom that determines an element’s chemical properties
RadiationThe release of particles or energy from an atom
Rem (Roentgen Equivalent Man)A standard unit of radiation dose that measures effects on humans
ReprocessingThe chemical treatment of spent fuel to recover residual fissionable material that can still be used as fuel in a nuclear reactor
ScramA rapid shut down of a nuclear reactor accomplished by moving control rods into the core to halt fission
ShieldingMaterial that blocks radiation, protecting people and equipment from radiation damage
SievertA unit of radiation dose equal to 100 rem
Spent fuelNuclear fuel that can no longer efficiently sustain a fission chain reaction
Questions or comments about the site? Contact the ANS Webmaster.