Areva - Reference Document 2016

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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 (UF6, which sublimates
at about 56 ) for the purpose of enriching it in fissile uranium (235U), 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.
2016 AREVA REFERENCE DOCUMENT 373