F

Date:2015-04-03 / DocumentISO/TC 85 / SC 1 1335–Comments / Project: Nuclear energy, nuclear technologies and radiological protection - Vocabulary - Part 5: Reactors
MB/ / Line / Clause/ / Paragraph/ / Typeof / Comments / Proposedchange / Observationsofthe
NC / number / Subclause / Figure/ / comment / secretariat
(e.g.17) / (e.g.3.1) / Table/
(e.g.Table1)
Gost-R / te / Terms haven’t been drafted. / See Attachment 1

1

F

Attachment 1

3.1 General terms related to nuclear reactors

activation
Тhe process of inducing radioactivity.
[SOURCE: IAEA Safety glossary:2007]
burnable absorber
Neutron absorbing material, used to control reactivity, with particular capability of being depleted by neutron absorption.
[SOURCE: IAEA Safety glossary:2007]
decay constant, λ
For a radionuclide in a particular energy state, the quotient of dP by dt, where dP is the probability of a given nucleus undergoing a spontaneous nuclear transition from that energy state in the time interval dt.

where N is the number of nuclei of concern existing at time t and A is the
activity.
Unit: reciprocal second (s–1).
The activity is the decay constant multiplied by the number of nuclei of the radionuclide present.
The decay constant is related to the radioactive half-life, T1/2, of the radionuclide by the expression:

[SOURCE: IAEA Safety glossary:2007]
fast neutron
neutron with a kinetic energy above a threshold, usually 0,1 MeV
[SOURCE: IEC 60050-395:2014, 395-02-12]
fissile material
Uranium-233, uranium-235, plutonium-239, plutonium-241 or any combination of these radionuclides. Excepted from this definition are:
(a) Natural uranium or depleted uranium which is unirradiated;
(b) Natural uranium or depleted uranium which has been irradiated in thermal reactors only.
[SOURCE: IAEA Safety glossary:2007]
fission product
A radionuclide produced by nuclear fission.
[SOURCE: IAEA Safety glossary:2007]
fluence rate (particle) flux density (particle)
The quotient of dφ by dt where dφ is the increment of particle fluence in the time interval dt:

[SOURCE: IEC 60050-881:2008, 881-04-19]
fluence, particle
At a given point in space, the sum of energies, the number of particles or photons incident during a given time interval on a small sphere centered at that point, divided by the cross-sectional area of that sphere. It is identical with the time integral of the particle flux density.
[SOURCE: ANSI N1.1-1976]
half-life, T½
1. For a radionuclide, the time required for the activity to decrease, by a radioactive decay process, by half.
2. The time taken for the quantity of a specified material (e.g. a radionuclide) in a specified place to decrease by half as a result of any specified process or processes that follow similar exponential patterns to radioactive decay.
[SOURCE: IAEA Safety glossary:2007]
heat transfer
Еxchange of heat between entities of different temperatures.
[SOURCE: IEC 60050-841:1983, 841-21-10]
high linear energy transfer radiation
Radiation with high linear energy transfer, normally assumed to comprise protons, neutrons and alpha particles (or other particles of similar or greater mass).
[SOURCE: IAEA Safety glossary:2007]
intermediate neutron
neutron of kinetic energy between the energies of slow and fast neutrons.
Note 1 to entry: The range is usually from 1 eV to 0,1 MeV.
[SOURCE: IEC 60050-395:2014, 395-02-14]
moderator
Material used to reduce, by scattering collisions and without appreciable capture, the kinetic energy of neutrons
[SOURCE: IEC 60050-395:2014, 395-07-14]
neutron
elementary uncharged nuclear particle
Note 1 to entry: mn = 939,565 379(21) MeV/c2 = 1,674 927 351(74) × 10−27 kg = 1,008 664 916 00(43) u.
Note 2 to entry: The free neutron mean life is 879,9 s.
[SOURCE: IEC 60050-395:2014, 395-01-04]
nuclear chain reaction
Set of fission reactions in which the neutrons necessary to produce a fission are themselves produced by a previous fission
Note 1 to entry: The reactions are called sub-critical, critical or supercritical depending on the ratio between the number of reactions of generation n+1 and generation n being less than, equal to or bigger than unity, respectively.
[SOURCE: IEC 60050-395:2014, 395-02-59]
nuclear fuel
Fissionable nuclear material in the form of fabricated elements for loading into the reactor core of a civil nuclear power plant or research reactor
[SOURCE: IAEA Safety glossary:2007]
nuclear fuel cycle
All operations associated with the production of nuclear energy, including: (a) Mining and processing of uranium or thorium ores; (b) Enrichment of uranium; (c) Manufacture of nuclear fuel; (d) Operation of nuclear reactors (including research reactors); (e) Reprocessing of spent fuel; (f) All waste management activities (including decommissioning) relating to operations associated with the production of nuclear energy; (g) Anyrelated research and development activities.
[SOURCE: IAEA Safety glossary:2007]
nuclear installations
- any nuclear reactor other than one with which a means of sea or air transport is equipped for use as a source of power, whether for propulsion thereof or for any other purpose;
- any factory using nuclear fuel for the production of nuclear material, or any factory for the processing of nuclear material, including any factory for the re-processing of irradiated nuclear fuel; and
- any facility where nuclear material is stored,
[SOURCE: Vienna Convention on Civil Liability for Nuclear Damage Article I]
nuclear reactor
Device in which a self-sustaining nuclear fission chain reaction can be maintained and controlled (fission reactor)
[SOURCE: ISO 921-97,837]
poison
A substance used to reduce reactivity in a reactor core, by virtue of its high neutron absorption cross-section.
[SOURCE: IAEA Safety glossary:2007]
reactivity, ρ
For a nuclear chain reacting medium:

where Keff is the ratio between the number of fissions in two succeeding generations (later to earlier) of the chain reaction.
A measure of the deviation from criticality of a nuclear chain reacting medium, such that positive values correspond to a supercritical state and negative values correspond to a subcritical state.
shutdown reactivity.
The reactivity when all control devices are
introducing their maximum negative reactivity.
A reactor is shut down quickly by moving control devices rapidly into position to introduce their negative reactivity into the core.
[SOURCE: IAEA Safety glossary:2007]
reactor coolant
Substance, usually a liquid, gas or molten metal, used for cooling any part of a nuclear reactor in which heat is generated [SOURCE: IEC 60050-395:2014, 395-07-37]
reflector
Material or body of material which reflects incident radiation
Note 1 to entry: In nuclear reactor technology, this term is usually restricted to designate a part of a nuclear reactor placed adjacent to the core for the purpose of returning some of the escaping neutrons back into the core by scattering collisions (without appreciable capture).
[SOURCE: IEC 60050-395:2014, 395-07-15]
self-sustained chain reaction
Nuclear chain reaction in which the number of reactions caused by one reaction is, on average, equal to unity.
[SOURCE: ISO 921:1997, 1104]
thermal neutron
neutron with a kinetic energy close to that of neutrons in thermal equilibrium with the atomic nuclei of the surrounding medium.
Note 1 to entry: In the case of a maxwellian nuclei distribution, the most probable energy is equal to 0,025 eV (1/40 eV) at 293 K.
Note 2 to entry: In practice the upper limit is about 1 eV.
[SOURCE: IAEA Safety glossary:2007]
thorium series: The decay chain of thorium-232. Namely, thorium-232, radium-228, actinium-228, thorium-228, radium-224, radon-220, polonium-216, lead-212, bismuth-212, polonium-212 (64%), thallium-208 (36%) and (stable) lead-208.
[SOURCE: IAEA Safety glossary:2007]
transport
The movement of something as a result of being carried by a medium.
[SOURCE: IAEA Safety glossary:2007]
uranium depleted uranium:
Uranium containing a lesser mass percentage of uranium-235 than in natural uranium.
enriched uranium:
Uranium containing a greater mass percentage of uranium-235 than 0.72%.
highly enriched uranium (HEU):
Uranium with a proportion of 235U high enough for use in nuclear weapons, typically over 90% by mass.
low enriched uranium (LEU):
Enriched uranium containing a lesser mass percentage of uranium-235 than 20%. natural uranium: Chemically separated uranium containing the naturally occurring distribution of uranium isotopes (approximately 99.28% uranium-238, and 0.72% uranium-235 by mass).
[SOURCE: IAEA Safety glossary:2007]
uranium series:
The decay chain of uranium-238. Namely, uranium-238, thorium-234, protactinium-234, uranium-234, thorium-230, radium-226, radon-222, polonium-218, lead-214, bismuth-214 and polonium-214, lead-210, bismuth-210, polonium-210 and (stable) lead-206, plus traces of astatine-218, thallium-210, lead-209, mercury-206 and thallium-206
[SOURCE: IAEA Safety glossary:2007]

3.2Terms related to nuclear reactor types

boiling water reactor
[SOURCE: GOST 23082-78[1]]
breeder
[SOURCE: GOST 23082-78]
converter
[SOURCE: GOST 23082-78]
demonstration reactor
[SOURCE: GOST 23082-78]
direct-cycle reactor
[SOURCE: GOST 23082-78]
electronuclear reactor
[SOURCE: GOST 23082-78]
experimental reactor
[SOURCE: GOST 23082-78]
fast reactor
[SOURCE: GOST 23082-78]
fusion reactor
[SOURCE: GOST 23082-78]
gas-cooled reactor
[SOURCE: GOST 23082-78]
graphite moderated reactor
[SOURCE: GOST 23082-78]
heavy water reactor
[SOURCE: GOST 23082-78]
heterogeneous reactor
[SOURCE: GOST 23082-78]
high temperature reactor
[SOURCE: GOST 23082-78]
homogeneous reactor
[SOURCE: GOST 23082-78]
hybrid fusion reactor
[SOURCE: GOST 23082-78]
inertial confined fusion reactor
[SOURCE: GOST 23082-78]
integral reactor
[SOURCE: GOST 23082-78]
intermediate reactor
[SOURCE: GOST 23082-78]
magnetic confined fusion reactor
[SOURCE: GOST 23082-78]
materials testing reactor
[SOURCE: GOST 23082-78]
metal liquid reactor
[SOURCE: GOST 23082-78]
multi-purpose reactor
[SOURCE: GOST 23082-78]
organic reactor
[SOURCE: GOST 23082-78]
pool reactor
[SOURCE: GOST 23082-78]
power reactor
[SOURCE: GOST 23082-78]
pressure tube reactor
[SOURCE: GOST 23082-78]
pressurized water reactor
[SOURCE: GOST 23082-78]
production reactor
[SOURCE: GOST 23082-78]
pulsed reactor
[SOURCE: GOST 23082-78]
pure fusion reactor
[SOURCE: GOST 23082-78]
reactor of thermionic conversion
[SOURCE: GOST 23082-78]
research reactor
[SOURCE: GOST 23082-78]
self-regulation reactor
[SOURCE: GOST 23082-78]
stationary reactor
[SOURCE: GOST 23082-78]
tank reactor
[SOURCE: GOST 23082-78]
thermal reactor
[SOURCE: GOST 23082-78]
thermoelectric reactor
[SOURCE: GOST 23082-78]
tokamak
[SOURCE: GOST 23082-78]
training reactor
[SOURCE: GOST 23082-78]

3.3Terms related to nuclear projects

cradle to grave approach
An approach in which all the stages in the lifetime of a facility, activity or product are taken into consideration.
[SOURCE: IAEA Safety glossary:2007]
design life
The period of time during which a facility or component is expected to perform according to the technical specifications to which it was produced.
[SOURCE: IAEA Safety glossary:2007]
nuclear worksite
[SOURCE: ISO/NP 16647 and PWI ISO 16647]
transportable reactor
[SOURCE: GOST 23082-78]

3.4 Terms related to nuclear power plants

capacity
The load for which a generating unit, generating station, or other electrical apparatus is rated either by the user or by the manufacturer. The ratio of the actual output divided by the ideal output is called the capacity factor. Primary capacity factors are maximum dependable capacity, based on a reference test of the unit, and design engineering reference, based on nominal plant design rating.
[IAEA-TECHNICAL REPORTS SERIES No. 437:2006]
capacity factor
The net electrical energy produced during the reference period versus the net electrical energy which would have been generated at maximum net capacity under continuous operation during the entire reference period, expressed in per cent.
[SOURCE:IAEA-TECDOC-1383]
energy availability factor
The ratio between the amount of energy available to be produced during a period versus the maximum amount of energy the plant could have been able to produce during the same period.
[SOURCE:IAEA-TECDOC-1383]
grid system
The grid system may refer to just the transmission system in a country, or in interconnected countries, or include both the transmission and distribution systems.
[IAEA-TECHNICAL REPORTS SERIES No. NG-T-3.8:2012]
nuclear power plant
Nuclear installation for the production of energy in a given mode and conditions of use, is located within a defined project area, which for this purpose is a nuclear reactor (s) and complex of necessary systems, devices, equipment and constructions with the necessary personnel (staff)
[SOURCE: RUSSIAN REGULATORY BASE (NP-001-97)]
nuclear unit
A nuclear unit comprises a nuclear reactor and all the auxiliary equipment (generator, transformers, motors, pumps, electrical supplies, protection systems etc.) that are required for its operation. A nuclear power plant (NPP) may have one or more nuclear units.
[IAEA-TECHNICAL REPORTS SERIES No. NG-T-3.8:2012]
unplanned capability loss factor
Unplanned capability loss factor is the percentage of maximum energy generation that a plant is not capable of supplying to the electrical grid because of unplanned energy losses (such as unplanned shutdowns, forced outages, outage extensions or load reductions). Energy losses are considered unplanned it they are not scheduled at least four weeks in advance.
[SOURCE:IAEA-TECDOC-1383]

3.6 Terms related to research and special purpose reactors

Experimental channel
[SOURCE: GOST 23082-78]
Thermal column
[SOURCE: GOST 23082-78]

3.7 Terms related to reactor and plant systems, structures and component s

active component
A component whose functioning depends on an external input such as actuation, mechanical movement or supply of power.[SOURCE: IAEA Safety glossary:2007]
actuated equipment
An assembly of prime movers and driven equipment used to accomplish one or more safety tasks.
[SOURCE: IAEA Safety glossary:2007]
actuation device
A component that directly controls the motive power for actuated equipment.
[SOURCE: IAEA Safety glossary:2007]
blanket
[SOURCE: GOST 23082-78]
blanket
[SOURCE: GOST 23082-78]
burnable poison rod
[SOURCE: GOST 23082-78]
bypass
1. A device to inhibit, deliberately but temporarily, the functioning of a circuit or system by, for example, short circuiting the contacts of a relay. 2. A route that allows fission products released from a reactor core to enter the environment without passing through the containment or other enclosure designed to confine and reduce a release in the event of an emergency. This route may be established intentionally by the operator or as a result of the event.
[SOURCE: IAEA Safety glossary:2007]
channel
[SOURCE: GOST 23082-78]
cladding
[SOURCE: GOST 23082-78]
containment
Methods or physical structures designed to prevent or control the release and the dispersion of radioactive substances.
[SOURCE: IAEA Safety glossary:2007]
control member
[SOURCE: GOST 23082-78]
control rod
[SOURCE: GOST 23082-78]
core
[SOURCE: GOST 23082-78]
core components
The elements of a reactor core, other than fuel assemblies, that are used to provide structural support of the core construction, or the tools, devices or other items that are inserted into the reactor core for core monitoring, flow control or other technological purposes and are treated as core elements.
[SOURCE: IAEA Safety glossary:2007]
divertor
[SOURCE: GOST 23082-78]
driven equipment
A component such as a pump or valve that is operated by a prime mover.
[SOURCE: IAEA Safety glossary:2007]
driver
[SOURCE: GOST 23082-78]
emergency shutdown rod
[SOURCE: GOST 23082-78]
equipment qualification.
Generation and maintenance of evidence to ensure that equipment will operate on demand, under specified service conditions, to meet system performance requirements.
[SOURCE: IAEA Safety glossary:2007]
first wall
[SOURCE: GOST 23082-78]
fuel assembly
A set of fuel elements and associated components which are loaded into and subsequently removed from a reactor core as a single unit.
[SOURCE: IAEA Safety glossary:2007]
fuel channel
[SOURCE: GOST 23082-78]
fuel element
A rod of nuclear fuel, its cladding and any associated components necessary to form a structural entity.
Commonly referred to as fuel rod in light water reactors.
[SOURCE: IAEA Safety glossary:2007]
functional isolation
Prevention of influences from the mode of operation or failure of one circuit or system on another.
[SOURCE: IAEA Safety glossary:2007]
independent equipment
Equipment that possesses both of the following characteristics:
(a) The ability to perform its required function is unaffected by the operation or failure of other equipment;
(b) The ability to perform its function is unaffected by the occurrence of the effects resulting from the postulated initiating event for which it isrequired to function.
[SOURCE: IAEA Safety glossary:2007]
item important to safety
An item that is part of a safety group and/or whose malfunction or failure could lead to radiation exposure of the site personnel or members of the public.
Items important to safety include:
— Those structures, systems and components whose malfunction or failure could lead to undue radiation exposure of site personnel or members of the public;
— Those structures, systems and components that prevent anticipated operational occurrences from leading to accident conditions;
— Those features that are provided to mitigate the consequences of malfunction or failure of structures, systems and components.
[SOURCE: IAEA Safety glossary:2007]
maintenance bypass
A bypass of safety system equipment during maintenance, testing or repair.
[SOURCE: IAEA Safety glossary:2007]
operational bypass A bypass of certain protective actions when they are not necessary in a particular mode of plant operation. An operational bypass may be used when the protective action prevents, or might prevent, reliable operation in the required mode.
[SOURCE: IAEA Safety glossary:2007]

passive component

A component whose functioning does not depend on an external inputsuch as actuation, mechanical movement or supply of power.
[SOURCE: IAEA Safety glossary:2007]
pellet
[SOURCE: GOST 23082-78]
plant equipment

[SOURCE: IAEA Safety glossary:2007]
pool
[SOURCE: GOST 23082-78]
primary containment
[SOURCE: GOST 23082-78]
prime mover
A component that converts energy into action when commanded by an actuation device.
[SOURCE: IAEA Safety glossary:2007]
reactor vessel
[SOURCE: GOST 23082-78]
reflector
[SOURCE: GOST 23082-78]
shim rod
[SOURCE: GOST 23082-78]

3.9 Terms related to nuclear safety, safety systems, features, abnormal conditions

accident conditions
Deviations from normal operation more severe than anticipated operational occurrences, including design basis accidents and severe accidents.
[SOURCE: IAEA Safety glossary:2007]
anticipated operational occurrence
(abnormal operation)
An operational process deviating from normal operation which is expected to occur at least once during the operating lifetime of a facility but which, in view of appropriate design provisions, does not cause any significant damage to items important to safety or lead to accident conditions.
[SOURCE: IAEA Safety glossary:2007]
common cause failure
Failure of two or more structures, systems and components due to a single specific event or cause.
[SOURCE: IAEA Safety glossary:2007]
common mode failure
Failure of two or more structures, systems and components in the same manner or mode due to a single event or cause. I.e. common mode failure is a type of common cause failure in which the structures, systems and components fail in the same way.