• Flag fr


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


ACRO : Association for the Control of Radioactivity in the West (France).

ACTINIDES : Group of chemical elements with an atomic number of at least 89 (actinium has an atomic number of 89). Four actinides occur naturally: actinium (89), thorium (90), protactinium (91) and uranium (92). Man-made actinides also exist, namely the transuranium elements: plutonium, americium, neptunium, and curium. A distinction is made between minor actinides, which cannot be recycled to generate electricity, and major actinides, which can be recycled, namely uranium and plutonium.

ACTIVATION : Process whereby atomic nuclei are made radioactive by neutron or gamma irradiation induced by a flux of neutrons or other particles.

ACTIVITY : Number of spontaneous disintegrations - or decays - occurring in atomic nuclei per unit time. The unit of activity is the becquerel (Bq).

AEROSOL : Suspension of solid or liquid particles - or both - in a gaseous medium, with negligible fall velocity. Under normal conditions in the air, aerosols have diameters of less than 100 micrometers, while the finest particles among them attain just fractions of a nanometer.

AFNOR : Association française de normalisation (French Standards Association).

ALPHA : (symbol α) Radiation composed of helium nuclei 4, strongly ionizing but not very penetrating. A single sheet of paper is sufficient to stop its spread.

ALQA : Lorraine Association for Air Quality (France).

ANCCLI : National Association of Local Information Commissions and Committees (France).

ANDRA : National Radioactive Waste Management Agency

ANSES : National Agency for Food, Environmental and Occupational Health Safety (France).

AREVA : Industrial group involved in the fuel cycle and in the manufacture of nuclear facilities. The Areva Group was created on September 3, 2001. As a result of the merger of CEA-Industrie, Framatome-ANP and COGEMA, Is today one of the world's leading players in the nuclear sector (France).

ARS : Regional Health Agency.

ASN : Nuclear Safety Authority (France).

ATOM : The basic unit of matter. It is made up of a nucleus (neutrons + protons) with electrons orbiting around it.


BECQUEREL : (Bq) official international unit of measurement used for radioactivity. The becquerel is equal to one transformation per second. The most common multiples are: mega (MBq) for 1 million becquerels, giga (GBq) for 1 billion becquerels, and tera (TBq) for one thousand billion becquerels. The most frequent submultiple is the millibequerel (mBq) representing one thousandth of a becquerel

BÊTA : Beta radiation (symbolized as β): radiation consisting of electrons with a positive or negative charge. Propagation can be stopped by leaving a space of a few meters around the source or providing a barrier using a simple sheet of aluminum foil.

BIG-BANG : Commonly accepted description of the history of the Universe. Initially extremely dense and warm, the Universe reaches its present state by combining expansion and cooling.

BNEN : Nuclear Equipment Standardization Office for Nuclear Facilities. One of the 31 sector standardization offices that make up the French national standardization system headed by AFNOR.


CEA : Alternative Energies and Atomic Energy Commission (France).

CESIUM : (Cs, atomic number 55): Toxic rare metal with characteristics comparable to those of potassium. The 134 and 137 isotopes are radioactive fission products with respective half-lives of 2.2 and 30.17 years.

CLI : Local Information Commission.

COFRACComité français d’accréditation - French Accreditation Committee.

CONTAMINATION : an undesirable level of radioactive substances (dust or liquids) on the surface or inside any matrix. Human contamination can be external (on the skin) or internal (by breathing or ingestion).

CRIIRADCommission de recherche et d’information indépendantes sur la radioactivité (France). - Commission for Independent Research and Information on Radioactivity.

CURIE : (symbol Ci) Historical unit measuring the activity of a radioactive source. The curie equals to 3.7 x 1010 becquerels, or to the activity of one gram of pure radium.


DARPE : applications for water intake and liquid effluent discharge permits.

DOSE RATE : Radiation intensity (energy absorbed by matter per unit mass and time). The SI unit is the gray per second (Gy/s).

RADIOACTIVE DECAY : natural decrease in the nuclear activity of a radioactive substance through spontaneous disintegration.

DISMANTLING : all the operations involved in removing the structural parts and other components of a decommissioned nuclear facility. Dismantling can be partial or total.

DETECTOR : device which detects radiation. Monitor with a detection zone, where radiation penetrates interacts in a way it creates a series of discrete events.

DGAL : Ministry of Agriculture, General Directorate on Food Safety.

DGCCRF : Consumer Affairs - General Directorate for Competition, Consumer Rights and Protection against Fraud.

DGDDI : General Directorate of Customs and Indirect Taxes.

DGS : Directorate General for Health.

DGPR : Direction générale de la prévention des risques - Directorate General for Risk Prevention is divided into the Technological Risks Department, which deals with radiological risks, the Department for the Prevention of Pollution and for Environmental Protection, and the Department for Natural and water-based Risks.

DISCHARGE PERMIT : Every facility in France must apply to the Ministries of Industry, Health, and the Environment for a discharge permit that sets limits on the liquid and gaseous waste that may be discharged, and defines the associated inspection conditions. The permit is granted by government order.

DOSIMETER : A dosimeter is a measuring device used to measure the radioactive dose or gamma dose equivalent rate received by a person exposed to ionizing radiation. There are two types of dosimeters: the nominative passive dosimeter (where the dose is integrated for a period of time and then measured in the laboratory) and the active dosimeter (where the measurement is performed instantly in situ). Under French regulations, wearing a dosimeter is compulsory for all workerslikely to be exposed to ionizing radiation.

DOSIMETRY : assessment or measurement of the ionizing radiation dose absorbed by a substance or an individual.

DREAL : Direction régionale de l’environnement, de l’aménagement et du logement (Regional Directorate for the Environment, Town and Country Planning and Housing).


EA : European cooperation for accreditation (French body is COFRAC).

EDF : Electricité De France, the French national electric utility.

EFFLUENTS : any radioactive or non-radioactive gas or liquid discharged by a facility.

ELECTRON : an elementary particle with a negative electrical charge. It is part of an atom.

ELEMENTARY PARTICLE : Fundamental subatomic particle that cannot be reduced or separated into smaller components and whose substructure is unknown. Elementary particles are the building blocks of the universe. All the other particles and matter in the universe are made up of elementary particles.
In the case of nuclei and radioactivity, the elementary particles are protons, neutrons, electrons, photons and neutrinos.

EMM : French naval staff.

EURODIF : European Gaseous Diffusion Uranium Enrichment Consortium.

EXPOSURE : the fact of being exposed to ionizing radiation (external exposure if the source is located outside the body, internal exposure if the source is located inside the body, etc.).


FBFC : Franco-Belgian Fuel Manufacturing Company.

FILIERE : Terme utilisé pour désigner un type de réacteurs nucléaires capables de produire de l’énergie. Il se définit par un ensemble de spécifications communes telles que la nature du combustible, le modérateur, la nature du fluide de refroidissement, etc. On distingue par exemple la filière uranium naturel-graphite-gaz (UNGG), les filières à eau légère, les filières à neutrons rapides (RNR)...

FISSILES : Describe atomic nuclei in which fission can be induced by capture of a single neutron. The energy configuration of fissile nuclei is very close to spontaneous fission.

FISSION : The splitting of an atom’s nucleus as a result of bombardment by neutrons. During this reaction, neutrons and ionizing radiation are emitted and a great amount of heat is released. Nuclear power plants use this heat to generate electricity.

FISSION PRODUCTS : Fragments of heavy nuclei produced by nuclear fission or the subsequent radioactive decay of nuclides formed by this process.

FUSION : a reaction in which two light nuclei unite to form a heavy nuclei. Energy is given off during this reaction. Research is under way to use the energy released by fusion to generate electricity.


GAMMA : (symbol : γ) high-penetration, but low-ionization, electromagnetic energy emitted when radioactive elements disintegrate. Protection is provided by concrete or lead screens.

NOBLE GASES : Gases with no chemical affinity that do not form compound readily. These are argon, helium, krypton, neon, radon and xenon.

GRAY : (symbol Gy) unit of energy transmitted to matter per unit mass (joule/kg) during absorption of a radiation dose.

GSIENGroupement de scientifiques pour l’information sur l’énergie nucléaire (France) - Organization of Scientists for Information about Nuclear Energy.


HELIUM 4 : nucleus consisting of two protons and two neutrons. This particularly stable assembly can be emitted by heavy nuclei as they seek stability. It is then known as an alpha ray.


IAEA : International Atomic Energy Agency.

ICPE : Installation classée pour la protection de l’environnement (environmentally regulated facility).

ILAC : International Cooperation on Laboratory Accreditation.

INB : Installation nucléaire de base (basic nuclear installation).

INBSInstallation nucléaire de base secrète (secret basic nuclear installation).

INTERACTION ELECTROMAGNETIQUE : Interaction à l’origine de l’attraction-répulsion entre les charges électriques, et de tous les phénomènes de magnétisme. Au niveau des particules, elle correspond à l’échange d’une particule sans masse et sans charge : le photon.

WEAK INTERACTION : Interaction of low intensity and range of less than 10-16 meters, it only manifests on our scale by the possibility that it offers to transmute a proton in neutron, or vice versa.

INTERACTION FORTE : Interaction qui lie les protons et les neutrons entre eux, et qui est à l’origine de la stabilité des noyaux atomiques.

INVS : National Institute of Health Watch..

IODINE : (I, atomic number 53): an elemental substance whose radioactive isotopes are found in fission products. All forms of radioactive iodine (131, 132, 133, etc.) are short-lived (for example, iodine-131 has a radioactive half-life of 8.02 days). The exception is iodine-129, which has a half-life of nearly 16 billion years.

IRSN : Institute for Radiological Protection and Nuclear Safety.

ISOTOPES : Elements whose atoms have the same number of electrons and protons, but a different number of neutrons. They have the same name and the same chemical properties. There are currently 325 known natural isotopes and 1,200 artificial isotopes.


LNHB : National Laboratory Henri Becquerel.


MW : Megawatt. The megawatt is equal to one million watts.


NEUTRINO : Elementary particle with no electric charge and unknown mass, emitted during weak interactions..

NEUTRON : Electrically neutral fundamental particle which, with the proton, makes up the nucleus of an atom. The neutron causes the nuclear fission reaction that provides the energy used in nuclear reactors.

NPP : Nuclear Power Plant (“CNPE”).

NUCLEUS : The positively charged central region of an atom. It contains almost all the mass of the atom, although it is ten thousand times smaller. The nucleus is composed of protons and neutrons bound by the strong interaction (or strong force).

NUCLEAR FUEL : fissile material forming the active part of a reactor core. In order for a fission chain reaction to take place, natural uranium, a mixture composed of 0.7% uranium-235, which is fissile, and 99.3% uranium-238, which is not fissile, must first be enriched to 4% uranium-235. This uranium is used as uranium oxide, which is particularly stable chemically.

NUCLEAR POWER PLANT / REACTOR SYSTEM : A set of power generating units that use the heat generated by atomic fission in a reactor. Its operating principle is identical to that of conventional thermal power stations. Only the fuel used and the technology are specific. There are different types of reactor systems in France: - natural uranium / graphite gas (decommissioned), - ordinary (or light) water, - heavy (decommissioned) water, - fast neutrons. Ordinary water power plants are the most widespread in the world, particularly those using the pressurized water system (abbreviated to REP: Pressurized Water Reactor (PWR)).

NUCLEAR SAFETY : All measures taken at all stages of the design, construction and operation of nuclear installations to prevent accidents and limit risks and consequences.


PHOTON : Elementary stable particle without electric charge and zero rest mass, a force carrier for the electromagnetic interaction. Also called light quantum, described as a electromagnetic wave or wave packet, minute energy packet of electromagnetic radiation. The smallest unit of light.

PLUTONIUM : (Pu, atomic number 94): transuranium element. Plutonium-239 has a half-life of 24,100 years.

POSITRON : Antiparticle of the electron, also called positive electron, positively charged subatomic particle having the same mass and magnitude of charge as the electron and constituting the antiparticle of a negative electron.

PROTON : Positively charged elementary particle which, with the neutron, makes up the nucleus of an atom.

PWR : Pressurized Water Reactor (“REP”). A nuclear reactor that uses uranium or a mixture of uranium and plutonium oxides for fuel, and ordinary water maintained at high pressure (155 bar to avoid vaporization) as coolant. French nuclear power is dependent on the use of this reactor design and the country has more PWR units in operation than any other country in the world.


RADIATION : Flow of atomic and subatomic particles and of waves, such as those that characterize heat rays, light rays, and X rays ; refers to the transfer of energy in light, electromagnetic or corpuscular form to matter (living or not) constantly bombarded with radiation of both types from cosmic and terrestrial sources.

RADIOACTIVE PERIOD : The time required for a radioactive substance to lose half of its radioactivity (i.e. half of the atoms in the substance decay), a certain period of time that is specific to that substance. This time period is called the radioactive period" or "half-life". The radioactive period varies from one radioelement to another: 110 minutes for argon 4, 8 days for iodine 131 and 4.5 billion years for uranium 238.

RADIOACTIVITY : process in which the unstable nucleus of certain several naturally occurring elements as well as of artificially produced isotopes of the elements, will decompose spontaneously, or decay, into a more stable configuration but will do so only in a few specific ways by emitting certain particles, certain forms of electromagnetic or ionizing radiation. Property exhibited by certain types of matter of emitting energy and subatomic particles spontaneously. It is, in essence, an attribute of individual atomic nuclei.

ALPHA DECAY : Emission of alpha rays, ie of nuclei of helium 4 by heavy nuclei. Type of radioactive disintegration in which some unstable atomic nuclei dissipate excess energy by spontaneously ejecting an alpha particle, produced when the heaviest elements decay. The alpha particle is an helium atom and contains two neutrons and two protons. It leaves the nucleus of an unstable atom at high speed. Alpha rays are not very penetrating and are easily absorbed.

BÊTA DECAY : Emission of beta rays ands particles, i.e. electrons, by unstable  nuclei. Nuclei with numerous neutrons emit electrons ("beta minus" rays), and nuclei with numerous protons emit positrons ("beta plus" rays).

Beta rays are much lighter energy particles. The beta particle is an energetic electron given off by the nucleus of unstable isotopes to restore an energy balance. Although the beta particle is around 8000 times smaller than the alpha particle, it is capable of penetrating much deeper into living matter. Each encounter with a living cell, and there may be many before the beta energy is dissipated, is likely to damage some of the chemical links between the living molecules of the cell or cause some permanent genetic change in the cell nucleus.

GAMMA DECAY : Emission of gamma rays, i.e. photons, by nuclei with an excess of energy. Gamma decay most often goes with alpha or beta decay.

Gamma "particle" is the very high energy "X-ray" called the gamma ray. It is an energetic photon or light wave in the same electromagnetic family as light and x-rays, but is much more energetic and harmful. It is capable of damaging living cells as it slows down by transferring its energy to surrounding cell components.

RADIOACTIVE WASTE MANAGEMENT : all the regulatory or technical provisions made and operations performed concerning radioactive waste, from generation up to and including disposal, aimed at protecting persons and the environment.

RADIOELEMENT : Natural or artificial radioactive element.

RADIONUCLIDE : A radioactive isotope of an element. Examples: 3H: tritium, a radioactive isotope of hydrogen. 14C: carbon-14, a radioactive isotope of carbon.

RADIATION PROTECTION : All the steps taken to protect the population and workers from the harmful effects of ionizing radiation.

RADIATION THERAPY : Use of the destructive power of radioactivity to destroy diseased cells, while minimizing damage to the healthy cells around them.

RADIATION : Electromagnetic waves (gamma) or particles (alpha and beta particles, neutrons) emitted when radionuclides decay. X-rays are also electromagnetic waves but are emitted by electron tubes. The term ‘ionizing’ radiation refers to radiation that produces ions as it passes through matter. Gamma, X- and ultraviolet rays and visible light are similar but do not have the same penetrating power or capacity to produce ions.

REACTOR SYSTEM : term used to describe types of nuclear reactors capable of generating energy. A reactor system is characterized by shared specifications, such as the type of fuel, the moderator, the type of coolant, etc. Reactor systems include, for example, the natural uranium graphite gas (UNGG) reactor, the gas-cooled reactors (GCR), light-water reactors, and fast neutron reactors (FNR).

RNM : National Radioactivity Measurement Network.


SCL : Service commun des laboratoires. (Joint Laboratory Service Unit), formerly the DGCCRF (Directorate for Competition, Consumer Rights, and Protection Against Fraud) laboratories. Since 1986, the year of the Chernobyl accident, the SCL has regularly monitored radioactivity levels in consumables.

SIEVERT (Sv): legal unit of dose equivalent (or effective dose) used to determine the biological effect produced by a given absorbed dose on a living organism. The dose equivalent is not a measurable physical quantity but is obtained by calculation. It depends on the energy transmitted to the tissue and the type of radiation and tissue involved.

SPECTROMETRY : method used to analyze the intensity of radiation emitted by a source according to its energy level. It can both identify radioelements and specify their ‘activity’.

SPENT FUEL PROCESSING : all the operations involved in extracting fissile and fertile materials (uranium and plutonium) from spent fuel for reuse, and for conditioning various categories of waste in a form compatible with storage or disposal.

SPRA : Service de Protection Radiologique des Armées. (Armed Forces’ Radiation Protection Department). The SPRA reports to the French Central Directorate for Defence Medical Services.

STORAGE: Temporary storage of radioactive waste.

STRONTIUM (Sr, atomic number 38): alkaline earth metal. Some of its isotopes are very widespread in nature, in particular strontium-90, which is taken up by bone tissue and has a half-life of 28.15 years.


TRANSMUTATION : conversion of one nuclide into another , modification of the number of neutrons or protons in a nucleus. The modification of the number of protons corresponds to the change of chemical element. It can occur by the radioactive decay of a nucleus, or the reaction of a nucleus with another particle.

TRANSURANIUM ELEMENTS : group of chemical elements heavier than uranium (atomic number 92). The main transuranium elements are neptunium (93), plutonium (94), americium (95), and curium (96).


URANIUM : Chemical element with atomic number 92 and symbol U, with three natural isotopes: uranium 234, uranium 235 and uranium 238. Uranium 235 is the only natural fissile nuclide, a quality that explains its use as a source of energy


WASTE : any residue from a production or transformation process or use, any substance, material produced or, more generally, any good that is no longer of any use to its owner and that is intended for disposal.

Return to top