Absorbed dose
The energy absorbed by a patient from decay of a radionuclide given for diagnostic or therapeutic purposes. Unit is gray(Gy).
Absorber
Any material that stops ionizing radiation. Some examples are lead, concrete, and steel attenuate gamma rays. A thin sheet of paper or metal will stop or absorb alpha particles and most beta particles.
Absorption
The process by which the number of particles or photons entering a body of matter is reduced by interaction with matter. Also the process in which energy is absorbed from the particles or photons even if the number is not reduced.
Actinides
Radioactive elements with atomic number larger than 88. (Note that actinium is not part of this group.)
Activation product
A radioactive material produced by bombardment with neutrons, protons, or other nuclear particles.
Air Launched Cruise Missile
A missile designed to be launched from an aircraft and jet engine powered throughout its flight. As with all cruise missiles, ALCM range is a function of payload, propulsion, and fuel volume and therefore can vary greatly. Under the START I Treaty, the term "long range ALCM" means an air launched cruise missile with a range in excess of 600 kilometers.
Air Sampling
The collection of samples of air to measure the radioactivity or to detect the presence of radioactive material, particulate matter, or chemical pollutants in the air.
Alpha decay
Radioactive decay in which an alpha particle (He4 nucleus) is emitted.
Alpha particle(alpha ray)
A positively charged particle (a Helium4 nucleus) made up of two neutrons and two protons. It is the least penetrating of the three common forms of radiation, being stopped by a sheet of paper. It is not dangerous to living things unless the alpha emitting substance is inhaled or ingested or comes into contact with the lens of the eye.
Alpha radiation
Emission of an alpha particle from a radionuclide. More damaging than the same dose of beta or gamma radiation but can be stopped by a sheet of paper. It has a positive charge.
Anti Ballistic Missile(ABM) System
Generally comprised of radars, sensors, launchers, and interceptors, this weapon system is intended to intercept and destroy long range ballistic missiles and their warheads in flight. The term is often used interchangeably with ballistic missile defense (BMD).
Anti Satellite Weapon(ASAT)
A system designed to destroy or disable enemy satellites in orbit.
Assembly (of nuclear fuel)
Takes the form of long tubes (pins) filled with fuel, usually mounted into arrays of up to 300 to go into a reactor. A typical pressurized water reactor core will contain about two hundred fuel assemblies.
Atom
A particle of matter indivisible by chemical means. It is the fundamental building block of elements.An atom has a relatively heavy nucleus made up of positively charged protons and neutral neutrons surrounded by orbiting electrons with a negative charge balancing that of the protons in the nucleus. The number of electrons (from I to 92) determines the chemical characteristics of the atom. The number of neutrons and protons (from I to 238) determines the weight and isotope of the atom.
Atomic Age
This began on 2 December 1942 with the creation of the first self sustaining nuclear chain reaction in a lab at the University of Chicago in the United States.
Atomic bomb
A weapon which uses fissionable material such as U235 to provide the explosive power. Bombs of this type were dropped on Hiroshima (6 August) and Nagasaki (9 August) in 1945. May be referred to as an A-bomb.
Atomic Energy Commission (AEC)
Federal agency created in 1946 to manage the development, use, and control of nuclear energy for military and civilian application.
Atomic mass
Originally defined as the number of protons and neutrons in the nucleus of an atom. Now measured in atomic mass units which are exactly one twelfth the mass of a neutral atom of carbon 12 (u7l.660 x 1027 kg.) The number assigned to each element on the basis of the number of protons found in the element's nucleus.
Atomic Vapor Laser Isotope Separation (AVLIS)
A method of uranium enrichment that uses a laser to excite and ionize a uranium atom of a specific uranium isotope so it can be selectively removed. The AVLIS process uses uranium metal vapor and a tuneable laser.
Background Radiation
Radiation from cosmic sources, naturally occurring radioactive materials and global fallout as it exists in the environment from testing of nuclear explosive devices. It does not include radiation from source, byproduct, or special nuclear materials regulated by the NRC. The typically quoted average individual exposure from background radiation is 360 millirems per year.
Ballistic Missile
A missile whose payload reaches its target by way of an initial powered boost and then a free flight along a high arcing trajectory. Part of the flight of longer range ballistic missiles may occur outside the atmosphere and involve the "reentry" of a warhead or the missile
Ballistic Missile Defense(BMD) System
A system, or measures, intended to intercept and destroy hostile ballistic missiles or their components (for example, reentry vehicles) in flight.
Becquerel(Bq)
The unit of radioactive decay equal to I disintegration per second. 3.7 X 1010 Bq =1 Curie.
Beta Particle
Charged particle emitted from a nucleus during radioactive decay, with a mass equal to 1/1837 that of a proton.A negatively charged beta particle is identical to an electron. A positively charged beta particle is called a positron. Large amounts of beta radiation may cause skin burns, and beta emitters are harmful if they enter the body. Beta particles may be stopped by thin sheets of metal or plastic.
Beta decay
Radioactive decay in which a beta particle is emitted.
Binary Chemical Weapon
A weapon containing two separate, relatively nontoxic chemicals that, when mixed, form a toxic agent.
Bioassay
The determination of kinds, quantities or concentrations, and in some cases, the locations of radioactive material in the human body, whether by direct measurement (in vivo counting) or by analysis and evaluation of materials excreted or removed from the human body.
Borosilicate glass
A type of glass containing at least 5% boric oxide. It is used in glassware that resists heat and is a leading candidate for use in high level waste immobilization and disposal.
Branching ratio
In branching radioactive decay, the fraction of nuclei that disintegrates in a specific way. (It is usually expressed as a percentage.)
Breeder Reactor
A nuclear reactor that produces more fissile material than it consumes while generating power
Burnup, specific
The total energy released per initial unit mass of reactor fuel as a result of the fission process occurring. The unit commonly used for specific burnup is megawatt/days per metric ton of initial heavy metal, MWd/MTIHM.
By product material
1) Any radioactive material (except special nuclear material) yielded in, or made radioactive by, exposure to the radiation incident or to the process of producing or utilizing special nuclear material. For purposes of determining the applicability of the Resource Conservation and Recovery Act to any radioactive waste, the term "any radioactive material" refers only to the actual radionuclides dispersed or suspended in the waste substance. The nonradioactive hazardous waste component of the waste substance will be subject to regulation under the Resource Conservation and Recovery Act; (2) the tailings or waste produced by the extraction or concentration of uranium or thorium from any ore processed primarily for its source material content. Ore bodies depleted by uranium solution extraction operations and which remain underground do not constitute "by-product material."
Calibration
The adjustment, as necessary, of a measuring device such that it responds within the required range and accuracy to known values of input.
Canister
metal container used for the storage or disposal of heat producing solid high level radioactive waste.
Capacity factor, plant
The ratio of the electrical energy actually supplied by a power plant in a given time interval to the electrical energy that could have been produced at continuous full power operation during the same time period.
Capsules
Encapsulated strontium and cesium high level wastes produced from defense reactor fuel reprocessing at the Hanford site.
Centrifuge
A spinning cylinder that uses centrifugal force to separate isotopes in gaseous form; used to enrich uranium.
Charged particle
Parts of an atom possessing a small charge of static electricity. A proton has a single unit of positive charge. An electron has a single unit of negative charge. A very large number of electrons passing through a conductor is called an electrical current.
Chain reaction
A reaction that initiates its own repetition. In nuclear fission, a neutron induces a nucleus to fission and releases neutrons which cause more fissions.
Cladding
A corrosion resistant tube, commonly made of zirconium alloy or stainless steel, surrounding the reactor fuel pellets which provides protection from a chemically reactive environment and containment of fission products.
Commissioning
All the detailed testing activities involved in putting a nuclear plant into service. Decommissioning is all the operations involved in reducing the plant to a safe state after its useful working life.
Comprehensive Test Ban Treaty (CTBT)
A proposed treaty to prohibit all testing of nuclear weapons in all environments-- underground, underwater, atmospheric, and in space. The latest effort to negotiate a CTBT began in the UN Conference on Disarmament in 1994 and ended in September 1996, with U.S. President Bill Clinton being the first to sign the treaty at the United Nations.
Concentrate
Frequently referred to as yellowcake, uranium concentrate is the refined chemical compound produced by uranium mines. Also commonly called U308 or uranium oxide, it is the usual internationally traded form of uranium.
Containment
The prevention of the release of unacceptable quantities of radioactive material into the environment by enclosing it tightly.
Contamination
The deposition of unwanted radioactive material on the surfaces of structures, areas, objects, or personnel. It may also be airborne or internal (inside components or personnel).
Control rods
A rod incorporating neutron absorbing materials, such as boron or cadmium. Control rods can be moved in and out of holes in the core of a reactor in order to control the reaction rate precisely.
Conversion, fuel
Chemical treatment of yellowcake to uranium hexafluoride in preparation for enrichment.
Coolant
A substance circulated through a nuclear reactor to remove or transfer heat. Coolants may be water, heavy water, carbon dioxide, helium, sodium and sodium-potassium alloy.
Core
Central region of a nuclear reactor, containing the fuel assemblies and moderator, in which the fission chain reaction takes place and the coolant is heated.
Cosmic Radiation
Penetrating ionizing radiation, both particulate and electromagnetic, originating in outer space. Secondary cosmic rays, formed by interactions in the earth's atmosphere, account for about 45 to 50 millirem of the 360 millirem background radiation that an average individual receives in a year.
Counter
A general designation applied to radiation detection instruments or survey meters that detect and measure radiation. The signal that announces an ionization event is called a count.
Counting Rules Procedures
Usually an assigned number, established to facilitate the counting of weapons loadings for arms control purposes.
Cow
A radioisotopic generator system
Critical mass
The minimum amount of fuel need in the core of a nuclear reactor in order to start a self sustaining chain reaction. When a reactor starts up it is said to "go critical".
Cruise Missile
As defined by the Intermediate Range Nuclear Forces Treaty, a cruise missile is "an unmanned, self propelled vehicle that sustains flight through the use of aerodynamic lift over most of its flight path." Such a missile may carry either a nuclear or conventional warhead.
Curie (Ci)
The basic unit used to describe the intensity of radioactivity in a sample of material. One curie equals thirty-seven billion disintegrations per second, or approximately the radioactivity of one gram of radium. Named for Marie and Pierre Curie, who discovered radium in 1898.
Daughter product(s)
The nuclide(s) formed by the radioactive decay of a different parent nuclide. In the case of radium 226, for example, there are 10 successive daughter products, ending in the stable isotope lead 206.
Decay (radioactive)
The change of one radioactive nuclide into a different nuclide by the spontaneous emission of alpha, beta, or gamma rays, or by electron capture. The end product is a less energetic, more stable nucleus. Each decay process has a definite half life.
Decay chain
A series of nuclides in which each member decays to the next member of the chain through radioactive decay until a stable nuclide has been formed.
Decay product
Nuclide or radionuclide produced by decay.
Decommissioning wastes
Wastes (generally low level) collected or resulting from facility decommissioning activities.
Decommissioning
Activities taken to reduce the potential health and safety impacts of commercial and DOE contaminated facilities, including removing a unit from operation and/or decontamination, entombment, dismantlement, or conversion of the site to another use.
Decontamination
Activities taken to remove unwanted (typically radioactive) material from facilities, soils, or equipment by washing, chemical action, mechanical cleaning, or other (treatment) techniques.
Delivery Vehicle
A ballistic or cruise missile or bomber that carries one or more warheads through its flight to target
Density
That property of a substance which is expressed by the ratio of its mass to its volume.
Depleted uranium
Uranium where the U235 isotope concentration is below the naturally occurring 0. 711 %.
Deployment
The placement of weapons, personnel, or equipment in a combat ready position.
Deuterium oxide (Heavy Water)
"Heavy Water" is the most effective moderator available for nuclear reactors. Heavy water occurs in natural water in approximately one part in 7000.
Deuterium
A stable naturally occurring hydrogen isotope. Its natural abundance is about one part in 7000 of hydrogen. Used in the form of deuterium oxide as a moderator.
Disintegration energy
The amount of energy released in a particular nuclear disintegration. This is usually expressed in MeV/disintegration.
Disintegration
Used to describe any process in which the arrangement of particles in the nucleus of an atom is disrupted, producing a change in the nature of the atom. It may happen spontaneously, in the case of a radioactive atom, or as a result of bombardment by other particles.
Dismantlement
The taking apart of a weapon system to comply with an arms control agreement.
Dose Equivalent
A term used to express the amount of biologically effective radiation dose when modifying factors have been considered.
Dose Rate
The radiation dose delivered per unit time. For example, rem per hour.
Dose
A general term denoting the quantity of radiation or energy absorbed in a specific mass. The energy of radiation can damage human living tissue by causing chemical changes in cells which can have biological effects. The amount of damage depends on the energy of the radiation, how much of it is absorbed, which parts of the body absorb it and the timing and duration of the absorption over lifetimes and generations. It expressed numerically in rads or grays.
Dosimeter
A portable instrument for measuring and registering the total accumulated dose to ionizing radiation.
Dosimetry
The theory and application of the principles and techniques involved in the measurement and recording of radiation doses.
Effective Half life
The time required for the amount of a radioactive element deposited in a living organism to be diminished by 50% as a result of the combined action of radioactive decay and biological elimination.
Electromagnetic radiation
A traveling wave motion resulting from changing electric or magnetic fields. Familiar electromagnetic radiation range from X-rays (and gamma rays) of short wavelength, through the ultraviolet, visible, and infrared regions, to radar and radio waves of relatively long wavelength. All electromagnetic radiations travel in a vacuum with the velocity of light.
Electron
An elementary particle with a negative charge and a mass l/ 183 7 that of the proton. Electrons surround the positively charged nucleus and determine the chemical properties of the atom.
Electron capture
A radioactive decay process in which an orbital electron is captured by and merges with the nucleus. The mass number is unchanged, but the atomic number is decreased by one.
Element
One of the 105 known chemical substances that cannot be broken down further
EMFIELD
Electric and Magnetic Fields
Enrichment, fuel
A nuclear fuel cycle process which increases the concentration of fissionable uranium (i.e., U235) in uranium ore above its natural level of 0.71%. (The method currently utilized in the United States is gaseous diffusion.)
Environmental Impact Statement
A report that documents the information required to evaluate the environmental impact of a project. Such a report informs decision makers and the public of the reasonable alternatives which would avoid or minimize adverse impacts or enhance the quality of the environment.
Environmental restoration
Cleanup and restoration of sites contaminated with radioactive and/or hazardous substances during past production, accidental releases, or disposal activities.
Equilibrium cycle
An assumed nuclear fuel cycle in which the feed and waste materials of a facility have constant compositions. In a reactor this condition typically results after the third or fourth fuel loading schedule.
Excited state
The state of an atom or nucleus when it possesses more than its normal energy. The excess energy is usually released eventually as a gamma ray.
Exposure
Being exposed to ionizing radiation or to radioactive material.
External Radiation
Exposure to ionizing radiation when the radiation source is located outside the body
Extremities
The hands, forearms, elbows, feet, knee, leg below the knee, and ankles. (Permissible radiation exposures in these regions are generally greater than the whole body because they contain less blood forming organs and have smaller volumes for energy absorption.)
Fabrication, fuel
Conversion of enriched uranium hexafluoride into pellets of ceramic uranium dioxide. These pellets are then sealed into corrosion resistant tubes of zirconium alloy or stainless steel. The loaded tubes, called fuel elements or rods, are then mounted into special assemblies for loading into the reactor core.
Fast (breeder) reactor (FBR)
A reactor without a moderator in which the fission chain reaction is sustained with high speed (fast) neutrons. It is capable of converting unused uranium 238 into plutonium fuel known as breeding which means that FBRs could be important in the future as a means of greatly extending the energy resources of uranium.
Fertile nuclide
A nuclide capable of being transformed into a fissile nuclide by neutron capture.
Film Badge
A pack of photographic film used for measurement of radiation exposure for personnel monitoring purposes. The badge may contain two or three films differing sensitivities, and it may contain a filter that shields part of the film from certain types of radiation.
First Strike
An initial attack on an opponent's strategic nuclear forces. Such an attack may be undertaken in an attempt to destroy an enemy's retaliatory (second strike) capability.
First Use
The introduction of nuclear weapons, or other weapons of mass destruction, into a conflict. A "no first use" pledge obliges a nation not to be the first to use such weapons.
Fissile
Capable of fission.
Fissile Material
The nuclear materials, such as U235 and Pu239, that are used to make nuclear weapons. U235 is the only naturally occurring fissile isotope
Fissile nuclide
A nuclide capable of undergoing nuclear fission with neutrons.
Fission products
Nuclides produced either by fission of heavy elements or by the subsequent decay of the nuclides thus formed. They are of medium atomic weight and almost all are radioactive. Examples: strontium 90, cesium 137
Fission, nuclear
The splitting of a heavy nucleus into two parts. This is accompanied by the release of energy and two or more neutrons. It may occur spontaneously or be induced by capture of bombarding particles, generally neutrons.
Fission, spontaneous
Nuclear fission that occurs without the addition of particles or energy to the nucleus.
Fuel assembly
A grouping of nuclear fuel rods that remains integral during the charging and discharging of a reactor core.
Fuel cycle, nuclear
The complete series of steps involved in supplying fuel for nuclear reactors. It includes mining, refining, UF6 conversion, enrichment, fabrication of fuel elements, use in a reactor, and management of radioactive waste. It may also involve chemical processing to recover the fissionable material remaining in the spent fuel, reenrichment of the fuel material, refabrication of new uel elements.
Fuel pellets
Smallest individual fuel component in a fuel assembly. Typically up to about 1.5 cm in length and up to 1 cm in diameter. One pellet contains more energy than one ton of coal and the latest advanced BWRs contain over 18 million pellets.
Fuel pin (element)
Nuclear fuel sealed into a tube of cladding material which radiates heat in the core of a reactor rather like the element of an electric kettle.
Fusion
The joining of two light nuclei such as helium or hydrogen to form a heavier nuclei. This is usually accompanied by the release of energy. The energy from the sun is produced by fusion.
Gamma radiation
High energy, short wavelength radiation emitted from the nuclei of atoms. Less damaging than the same dose of alpha radiation, but much more penetrating. Can be stopped by thick slabs of lead or concrete.
Gamma ray
A highly penetrating type of nuclear radiation, similar to X-rays, except that it comes from within the nucleus of an atom, and, in general, has a shorter wavelength.
Gaseous Diffusion
A method of uranium enrichment used to separate U235 from U238 based on the fact that gas atoms or molecules with different masses diffuse through a porous barrier (or membrane) at different rates.
Geiger Mueller counter
A radiation detection and measuring instrument. It consists of a gas-filled tube containing electrodes, between which there is an electrical voltage, but no current flowing. When ionizing radiation passes through the tube, a short, intense pulse of current passes from the negative electrode to the positive electrode and is measured or counted. The number of pulses per second measures the intensity of the radiation field. It was named for Hans Geiger and W.Mueller, who invented it in the 1920's. It is sometimes called simply a Geiger counter or a G/M counter.
Generation (electricity)
The process of producing electric energy from other forms of energy; also, the amount of electric energy produced, commonly expressed in kilowatt/hours (kWh) or megawatt/years [MW(e)/years].
Generation (gross)
The total amount of electric energy produced by the generating units in a generating station measured at the generator terminals.
Generation (net)
Gross generation minus the electric energy consumed at the generating station for station use.
Generation (waste)
The origination of new wastes from various facility operations (including production, rework, decontamination and decommissioning, and environmental restoration), including the recovery of pre 1970 transuranic produced wastes, should their recovery be determined necessary.
Glass frit
A fusible ceramic mixture used to make glass for use in the immobilization and disposal of high level wastes.
Graphite
A dense black crystalline form of pure carbon which is an efficient moderator of neutrons; i.e. slows them down.
Gray
SI unit of absorbed dose.
Named after L. H. Gray, the British radiation biologist, and equal to the absorption of one joule of energy in one kilogram of tissue. The older unit rad is one hundred times smaller than the gray.
Ground Launched Cruise Missile (GLCM)
A missile launched from a land based system that is jet engine powered throughout its flight.
Grout
A mortar or cement mixture used to immobilize radioactive wastes.
Gy
Doses are measured in grays, 1 gray (Gy) being equal to an amount of radiation that releases 1 joule of energy per kilogram of matter.