R
Rad
Acronym for radiation absorbed dose, the basic unit of absorbed dose of radiation. A dose of one rad means the absorption of 100 ergs (a small but measurable amount of energy per grain of absorbing tissue).
Radiation Absorbed Dose
The basic unit of an absorbed dose of ionizing radiation. One rad is equal to the absorption of 100 ergs of radiation energy per gram of matter.
Radiation Area
Any area with radiation levels greater than 5 mrem.
Radiation sickness syndrome
The complex of symptoms characterizing the disease known as radiation injury, resulting from excessive exposure of the whole body (or large part) to ionizing radiation. The earliest of these symptoms are nausea, fatigue, vomiting, and diarrhea, which may be followed by loss of hair (epilation), hemorrhage, inflammation of the mouth and throat, and general loss of energy. In severe cases, where the radiation exposure has been relatively large, death may occur within two to four weeks. Those who survive six weeks after the receipt of a single large dose of radiation may generally be expected to recover.
Radiation source
Usually a martmade sealed source of radiation used in teletherapy, radiography, as a power source for batteries, or in various types of industrial gauges. Machines such as accelerators and radioisotope generators and natural radionuclides may be considered sources.
Radiation Warning Symbol
An officially prescribed symbol (a magenta or black trefoil) on a yellow background that must be displayed where certain quantities of radioactive materials are present or where certain doses of radiation could be received.
Radiation Dectection Instrument
A device that detects and records the characteristics of ionizing radiation.
Radiation
Energy given off by atoms when they are moving or changing state. Can take the form of electromagnetic waves, such as heat, light, X rays, or gamma rays, or streams of particles such as alpha particles, beta particles, neutrons or protons.
Radiation Shielding
Reduction of radiation by interposing a shield of absorbing material between any radioactive source and a person, work area, or radiation sensitive device.
Radiation Standards
Exposure standards, permissible concentration, rules for safe handling, regulations for transportation, regulations for industrial control of radiation, and control of radioactive material by legislative means.
Radioactive contamination
Deposition of radioactive material in any place where it may harm persons or equipment.
Radioactive dating
A technique for estimating the age of an object by measuring the amounts of various radioisotopes in it.
Radioactive waste
Materials which are radioactive and for which there is no further use.
Radioactive
Exhibiting radioactivity or pertaining to radioactivity.
Radioactivity
The spontaneous emission of radiation, generally alpha or beta particles, often accompanied by gamma rays, from the nucleus of an unstable isotope.
Radiography
The making of a shadow image on photographic film by the action of ionizing radiation.
Radioisotope
An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation. Approximately 5,000 natural and artificial radioisotopes have been identified.
Radiological Survey
The evaluation of the radiation hazards accompanying the production, use, or existence of radioactive materials under a specific set of conditions. Such evaluation customarily includes a physical survey of the disposition of materials and equipment, measurements or estimates of the levels of radiation that may be involved, and a sufficient knowledge of the processes affecting these materials to predict hazards resulting from expected or possible changes in materials or equipment.
Radiology
That branch of medicine dealing with the diagnostic and therapeutic applications of radiant energy, including X-rays and radioisotopes.
Radiometric
Using radiation for detection.
Radionuclide
A radioactive nuclide. An unstable isotope of an element that decays or disintegrates spontaneously, emitting radiation.
Radiosensitivity
The relative susceptibility of cells, tissues, organs, or other substances to the injurous action of radiation.
Radium (Ra)
A radioactive metallic element with atomic number 88. As found in nature, the most common isotope has a mass number of 226. It occurs in minute quantities associated with uranium in pitchblende, carnotite, and other minerals.It is a decay product of uranium.
Radon
An odourless, invisible, heavy gas which is the most significant source of natural radiation exposure. Its solid decay products, radon daughters, decay quickly, but can be inhaled and irradiate the lungs.
Rate meter
An electronic instrument that indicates, on a meter, the number of radiation induced pulses per minute from radiation detectors such as a Geiger-Muller tube.
Reactivity coefficient
The ratio of change in reactivity to a change in a specified parameter: temperature, pressure, void, power and mass.
Reactivity
The departure of a reactor system from criticality; positive reactivity addition means a move towards power increase; negative a move towards power decrease.
Reactor, boiling water
A light water reactor in which water, used as both coolant and moderator, is allowed to boil in the core. The resulting steam is used directly to drive a turbine.
Reactor, breeder
A reactor that produces more fissionable fuel than it consumes. The new fissionable material is created by a process (breeding) in which fission neutrons are captured in fertile materials.
Reactor, fast flux
A reactor in which fission is induced predominantly by fast neutrons.
Reactor, high-temperature, gas-cooled
A nuclear reactor that uses an inert gas (helium) as the primary coolant and graphite as the moderator.
Reactor, light-water
A nuclear reactor that uses light water as the primary coolant and moderator, with slightly enriched uranium as the fuel. There are two types of commercial light-water reactors: boiling-water and pressurized-water.
Reactor, naval propulsion
A reactor used to power a vessel or submarine of the U.S. Navy.
Reactor, pressurized-water
A light-water reactor in which heat is transferred from the core to a heat exchanger via water kept under high pressure, so that high temperatures can be maintained in the primary coolant system without boiling the water. Steam is generated in a secondary circuit.
Reactor, production
A reactor whose primary purpose is to produce fissile or other materials or to perform irradiations on an industrial scale. Unless otherwise specified, the term usually refers to either a tritium or plutonium-production facility used to produce materials for nuclear weapons.
Reactor, research
A reactor whose nuclear radiations are used primarily as a tool for basic or applied research. Typically, it has a thermal power of 10 MW(t) or less and may include facilities for testing reactor materials.
Reactor, test
A reactor associated with an engineering scale test program conducted to develop basic design information or demonstrate safety characteristics of nuclear reactor systems.
Reconversion
Process of converting enriched UF 6 back into a solid oxide form, typically UO2, prior to manufacture of fuel pellets.
Redox
Where an oxidising agent is reduced and a reducing agent is oxidised.
Reentry Vehicle (RV)
A nuclear warhead on a ballistic missile specially designed to reenter the earth's atmosphere in the terminal portion of the missile's trajectory.
Reinserted fuel
Irradiated reactor fuel that is discharged in one cycle and inserted into the same reactor during a subsequent refueling. In a few cases, fuel discharged from one reactor has been used to fuel a different reactor.
Remote handling
Techniques used for the handling of radioactive materials behind the protection of walls which will absorb the radiation. It includes the use of robotics in radioactive areas.
Rem
The special unit of dose equivalent. The dose equivalent equals the absorbed dose multiplied by the quality factor.
Repository
A permanent resting place for radioactive wastes, which will finally decay to natural levels of radioactivity.
Reprocessing
The chemical treatment of spent reactor fuel to separate the plutonium and uranium from the spent fuel rods and from each other to be used again as fuel. This allows recycle of valuable fuel material and minimizes the volume of high level waste materials. Britain, Russia, France, Germany, and Japan are currently reprocessing to recover plutonium.
RepU (Reprocessed Uranium)
RepU is uranium extracted from spent fuel which may return to the fuel cycle to be fabricated as new fuel. RepU has a different isotopic composition to "fresh" uranium and generally contains higher proportions of U-232, U-234 and U-236.
Restricted Area
Any area to which access is controlled for the protection of individuals from exposure to radiation and radioactive materials.
Roentgen (R)
A unit of exposure to ionizing radiation. It is the amount of gamma or X-rays required to produce ions resulting in a charge of 0.000258 coulombs/kilogram of air under standard conditions. Named after Wilhelm Roentgen, German scientist who discovered X-rays in 1895.
S
Salt cake
A salt form of high-level waste stored in tanks, which is produced from neutralizing acidic liquid waste from defense reactor fuel reprocessing with an alkaline agent (caustic soda).
Scaler
An electronic instrument for counting radiation induced pulses from radiation detectors such as a Geiger-Muller tube.
Scattered Radiation
Radiation that, during its passage through a substance has been changed in direction. It may also have been modified by a decrease in energy. It is one form of secondary radiation.
Scintillation counter
An instrument that detects and measures gamma radiation by counting the light flashes (scintillations) induced by the radiation.
Scintillation Detector
The combination of phosphor, photo multiplier tube and associated electronic circuits used to count light emissions produced in the phosphor by ionizing radiation.
Sea dumping (disposal)
The practice of periodically dumping shiploads of drummed, solidified waste into the ocean at specified locations. (No longer performed.)
Seabed Treaty
Signed by the United States on February 11, 1971, this multilateral treaty prohibits the placement of nuclear weapons or other weapons of mass destruction on the seabed beyond a 12-mile zone.
Sea Launched Cruise Missile (SLCM)
A missile designed to be launched from a surface ship or submarine and jet engine powered throughout its flight.
Secondary Radiation
Radiation originating as the result of absorption of other radiation in matter. It may be either electromagnetic or particulate in nature.
Secular equilibrium
A state of parent-daughter equilibrium which is achieved when the half-life of the parent is much longer than the half-life of the daughter. In this case, if the two are not separated, the daughter will eventually be decaying at the same rate at which it is being produced. At this point, both parent and daughter will decay at the same rate until the parent is essentially exhausted.
Separative work unit
The standard measure of enrichment services, measuring the effort expended in increasing the U-235 content of uranium above the natural 0.711%. It typically measures the amount of enrichment capacity required to produce a given amount of enriched uranium from a particular feed material, while enrichment plant capacities are quoted in SWUs per annum. It is defined by a mathematical formula.
Shielding
A protective barrier, usually a dense material, which reduces the passage of radiation from radioactive materials to the surroundings.
Shorter Range Intermediate Nuclear Forces (SRINF) Missiles
Missiles with ranges between 500 and 1,000 kilometers.
Short Range Attack Missile (SRAM)
An air to surface missile with a range under 600 miles (960 kilometers) carried by U.S. bomber aircraft.
Shut down
Stopping of the fission chain reaction in a reactor by inserting neutron absorbing control rods into the core.
Also referred to as reactor.
Sievert (Sv)
The unit of dose equal to 1 Joule/kilogram.I Sv = 100 rem.
Silo
Hardened underground facilities for housing and launching a ballistic missile and designed to provide pre launch protection against nuclear attack.
Single-shell tank wastes
High-level wastes, generated from defense reactor fuel reprocessing at Hanford, which are stored in single-shelled tanks. These tanks contain inventories of liquid, sludge, and salt cake. See also "double-shell tank wastes."
Slurry, high-level waste
A watery mixture of highly radioactive, insoluble matter.
Solvent extraction
The separation of materials of different chemical types and solubilities by selective solvent action; used to recover and separate uranium and plutonium in reprocessing spent nuclear fuel.
Source
A radioactive material that produces radiation for experimental or industrial use.
Special nuclear material
Plutonium, or uranium enriched to a higher than natural assay.
Specific activity
The number of radioactive decays that take place per unit mass. In general this means that a low specific activity material releases a relatively small amount of radiation.
Specific uranium consumption
Uranium consumption per unit of electricity output.
Spent Fuel (in reactor operations)
Fuel elements that have been used in the nuclear fuel cycle and removed from the reactor because they contain too little fissile material and too high a concentration of radioactive fission products. They are highly radioactive. Also referred to as irradiated fuel or used fuel.
Spent Fuel Storage Pools
Water filled pools in which spent fuel may be stored awaiting further disposition.
Spent fuel
Nuclear fuel that has been permanently discharged from a reactor after it has been irradiated. Typically, spent fuel is measured in terms of either the number of discharged fuel assemblies or the quantity of discharged fuel mass. The latter is measured either in metric tons of heavy metal (i.e., only the heavy metal content of the spent fuel is considered) or in metric tons of initial heavy metal (essentially, the initial heavy metal mass of the fuel before irradiation). The difference between these two quantities is the weight of the fission products produced during irradiation.
Spill
The accidental release of radioactive materials.
Stable
Non radioactive
Strategic Nuclear Forces
Land based ballistic missiles with ranges over 5,500 kilometers, modem submarine launched ballistic missiles, and heavy bombers.
Submarine Launched Ballistic Missile (SLBM)
A ballistic missile that is carried aboard and launched from a submarine.
Survey
A study to: 1) Find the radiation or contamination level of specific objects or locations within an area of interest 2) Locate regions of higher than average intensity, i.e. hot spots.
Survey Meter
Any portable radiation detection instrument especially adapted for inspecting an area to establish the existence and amount of radioactive material present.
SWU
Separative work unit
T
Tactical Nuclear Weapons
Nuclear weapons, such as artillery shells, bombs, and short range missiles, for use in battlefield operations.
Tails assay
The concentration of the U 235 isotope remaining in tails material, again most applicable to depleted uranium from enrichment.
Tails
Common term for the residual waste from mining and milling, also frequently applied to depleted uranium from enrichment.
Terrestrial Radiation
A portion of the natural radiation (background) emitted by naturally occurring radioactive materials on earth.
Theater High Altitude Area Defense (THAAD) System
A U.S. theater missile defense system designed to intercept ballistic missiles with ranges up to 3,500 kilometers.
Theater Missile Defense
Missile defenses intended to protect troops from short and medium range missile attack (see Anti Ballistic Missile System and Ballistic Missile Defense).
Theater Nuclear Forces
Nuclear forces designed for localized military missions.
Thermal power stations
Power stations that use a source of heat nuclear energy or coal or oil burning to generate steam and drive a turbine generator to produce electricity. So called to distinguish them from hydro power plants.
Thermal power
A measure of the rate of heat energy emission that results from the radioactive decay of a material. A unit of thermal power commonly used is the watt (W).
Thermal reactor
Nuclear fission reactor which uses moderated (slow or "thermal") neutrons; e.g. Magnox, light water or Candu reactors. Reactors without a moderator are referred to as fast reactors.
Thermoluminescent Dosimeter
A device used to measure radiation by measuring the amount of visible light emitted from a crystal in the detector when exposed to radiation.
Throw weight
This term refers to the weight of the payload that a missile is capable of delivering and is a measure of the destructive potential of a ballistic missile.
Tokamak
A tokamak is a toroidal plasma confinement device invented in the 1950s by the Russians Tamm and Sakharov.
Toxins
Chemical weapons produced through biological or microbic processes.
Tracer
A small amount of radioactive isotope introduced into a system in order to follow the behavior of some component of that system.
Transmutation
The changing of atoms of one element into another element by bombardment with nuclear particles; e.g. uranium-238 into plutonium or thorium into uranium-233 by neutron bombardment.
Trip
A reactor scram is sometimes referred to as a trip.
U
UN Register of Conventional Arms
Created by the United Nations in December 1991, this is a register to which states voluntarily report their arms exports and imports in seven major categories of weapons.
UN Special Commission (UNSCOM)
A commission created by the United Nations Security Council to carry out on site inspection and elimination of Iraq's weapons of mass destruction and ballistic missiles with a range greater than 150 kilometers.
UN (United Nations)
Established in 1945. Membership presently includes 185 states. The UN has nine central organs: the General Assembly, the Security Council, the Secretariat, the Economic and Social Council, the Trusteeship Council, the International Court of Justice, the United Nations Conference on Trade and Development, the Office of the United Nations High Commissioner for Refugees, and the United Nations Children's Fund. In addition, there are many agencies and organizations affiliated with the UN including the International Monetary Fund, the General Agreement of Tariffs and Trade, and the World Bank. Also important are the following :UN Disarmament Commission (UNDC). Established in 1952, and later re established in 1978. Membership universal.
Uranium hexafluoride
(UF6) Compound of uranium and fluorine used in its gaseous state in the enrichment process. Produced in conversion plants.
Uranium
A naturally occurring radioactive element whose principle isotopes are U-238 and U-235. The primary use for uranium is as a source of fuel for nuclear power reactors. When highly enriched by increasing the percentage of U-235 isotopes, it may also be used in nuclear weapons. Its atomic number is 92.
V
Vitrification
Incorporation of radioactive waste materials into a solid ingot of glass, sealed in a steel container, for disposal in a repository.
W
Warhead
Explosive part of a nuclear weapons system. Warheads consist of nuclear materials, conventional high explosives, and related firing mechanisms.
Waste management
All the procedures for treatment of radioactive waste materials, safe storage and eventual disposal
Watt
Unit of power. A typical light bulb consumes 100 watts. A one bar electric fire consumes 1 kilowatt (1,000 watts). A commercial nuclear reactor produces 600 to 1,300 megawatts (million watts) of electricity.
Weaponization
The process of constructing a nuclear device, or testing its component parts separately, or in a weapon model, to validate its design. Component and model testing require special instruments, many of which are dual use in character.
Weapons retirement
The process by which nuclear weapons are determined to be obsolete or unnecessary for national defense. A retired weapon or weapon system is no longer in an active status or deliverable, but may still be a fully functioning nuclear device.
Weapons Grade Material
Nuclear material considered most suitable for a nuclear weapon. It usually connotes uranium enriched to above 90 percent Uranium-235 or plutonium with greater than 90 percent Pu-239. (Crude weapons can be fabricated from lower grade material.)
Whole Body Counter
A device used to identify and measure the radioactive material in the body (body burden) of human beings and animals. It uses heavy shielding to keep out background radiation and ultra sensitive radiation detectors and electronic counting equipment.
Whole Body Exposure
An exposure of the body to radiation, in which the entire body, rather than an isolated part, is irradiated. Where a radioisotope is uniformly distributed throughout the body tissues, rather than being concentrated in certain parts, the irradiation can be considered as whole body exposure.
Wipe Sample
A sample made for the purpose of determining the presence of removable radioactive contamination on a surface. It is done by wiping, with slight pressure, a piece of soft filter paper over a representative type of surface area. It is also known as a "swipe sample."
X
X-ray
Penetrating electromagnetic radiation (photon) having a wavelength that is much shorter than that of visible light.These rays are usually produced by excitation of the electron field around certain nuclei. In nuclear reactions, it is customary to refer to photons originating in the nucleus as gamma rays, and to those originating in the electron field of the atom as X-rays.These rays are sometimes called roentgen rays after their discoverer, W.K. Roentgen.
Y
Yellowcake
Refined chemical compound of uranium, the form in which uranium is usually shipped from the mine to the nuclear fuel manufacturer.
Yield
The amount of energy released by a nuclear explosion, generally measured in equivalent tons of TNT. A kiloton is equivalent to 1,000 tons of TNT; a megaton is equivalent to one million tons of TNT.
Z
Zero Option
A U.S. proposal in the context of the intermediate range nuclear forces negotiations to eliminate intermediate range ballistic missiles.
Zero Yield
The absence of the release of any nuclear energy. A "zero yield" comprehensive test ban treaty bans all nuclear weapons test explosions (see Yield).
Zirconium Metallic element
An alloy of zirconium known as Zircaloy is extensively used for the canning, or cladding, of nuclear fuel elements for watercooled reactors