Areva - Reference Document 2016

GLOSSARIES 1. Technical glossary

> Compact Linear Fresnel Reflector (CLFR) Technology using rows of flat or very slightly curvedmirrors to concentrate the sun’s rays towards a fixed horizontal linear receptor consisting of a tube or a bundle of tubes in which the heat transfer fluid flows. The operating fluid is heated by the incident rays of the sun. When the fluid is water, it is referred to as direct steam generation technology (DSG). The luminous energy is converted into thermal energy; the water is heated and converted into steam, and may subsequently be superheated. The steam can then be used directly as process steam for industrial applications or sent to a turbine to generate electricity. > Concentrated solar power plant (CSP) Power plant in which the source of heat is a solar field. The field consists of mirrors that concentrate the sun’s rays on a fluid, raising its temperature, so that luminous energy can be converted to thermal energy. The thermal energy is then converted into mechanical energy and finally into electrical energy via a turbine. > Containment System of protection that consists of containing radioactive products inside a defined area. > Containment area During the construction of a facility designed to contain radioactive materials, a series of containment barriers is put up between the materials inside and the environment outside the facility as part of the engineered structures. This creates separate areas called “containment areas”. > Containment barrier System capable of preventing or limiting the dispersion of radioactive materials. > Contamination Presence of radioactive substances (dust or liquid) on the surface or inside a medium. Contamination in humans may be external (on the skin) or internal (via the skin or the respiratory or digestive tracts). > Controlled areas Areas where access and conditions for residence time are restricted for reasons of radiation protection. > Control rods Made of neutron-absorbing chemical elements such as boron or hafnium, these rods, often assembled as “clusters”, are inserted in the core of a nuclear reactor to control the chain reaction, i.e. to regulate the neutron flux. > Conversion Series of chemical transformations that convert the solid uranium concentrate (usually in the form of an oxide) into uranium hexafluoride (UF 6 , which sublimates at about 56 ) for the purpose of enriching it in fissile uranium ( 235 U), and vice versa. > Coolant, heat transfer fluid Fluid flowing in the core of a nuclear reactor (coolant) or in the recipient of a solar steam generator (heat transfer fluid) to transfer heat.

> Criticality A medium containing a fissile nuclear material becomes critical when neutrons are produced by fission of the material at the same rate as they dissipate through absorption and/or escape to the outside. To sustain a fission chain reaction, a continuously operating reactor must be maintained in a critical state. In a subcritical state, not enough neutrons are produced and the reaction stops. In a supercritical state, too many neutrons are produced and a runaway nuclear reaction can occur that can rapidly get out of control. > CSP (concentrated solar power) Concentrated solar power is one way to use solar radiation directly. The technology consists of concentrating solar radiation to heat a fluid to a high temperature and then generate electricity using a turbine, or provide process steamor heat to industry. > Cumac Name of the accounting unit used in the French system for “white certificates”, or energy consumption reduction certificates. “Cumac” is a combination of the French words for cumulative ( cumulé ) and discounted ( actualisé ) over the product lifecycle. kWh Cumac and GWh Cumac are typically used. > Decay Natural reduction of the activity of a radioactive substance through spontaneous disintegration. > Decommissioning Administrative procedure consisting of removing a facility from the list of regulated nuclear facilities (INB). At that point, the facility is no longer subject to the legal and administrative requirements pertaining to regulated nuclear facilities. > Decontamination Decontamination is a physical, chemical or mechanical operation designed to eliminate or reduce the presence of radioactive or chemical materials deposited on a person or equipment, or in a facility or open area. > Defense in depth A series of lines of defense designed to prevent the appearance, or limit the consequences as necessary, of human or technical failures that could lead to accidental situations. > Deuterium Isotope of hydrogen whose nucleus consists of one proton and one neutron. > Dismantling Technical and administrative procedures carried out following the final shutdown of a nuclear facility to achieve a designated final state enabling it to be decommissioned. Besides the physical dismantling of all machinery and equipment, dismantling includes decontamination and radioactive waste management. > Dose Measurement of the exposure of an individual to radiation. Exposure is a function of the energy received and the effects related to the type of radiation. Doses are measured in millisieverts (mSv), a subunit of the sievert (Sv) (1 Sv = 1,000 mSv). The mean annual dose from exposure to natural background radiation in France is 2.4 mSv/person.

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2016 AREVA REFERENCE DOCUMENT