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Nuclear reactors (analogue computers therefor G06G 7/54; fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
Definition statement
This subclass/group covers:

All aspects related to nuclear fission reactors and their components, i.e. all aspects related to the reactors per se, in particular all parts strictly related to the primary cooling circuit of the reactor, as well as monitoring or testing of nuclear fission reactor parameters and components, arrangements for handling nuclear fission reactor components or material and apparatuses and processes adapted to manufacture nuclear fission reactors.

References relevant to classification in this subclass
This subclass/group does not cover:
Nuclear fusion reactors
Treating radioactively contaminated materials; Decontamination arrangements therefor
Nuclear explosives and their application
Arrangements of nuclear propulsion power plant or units on marine vessels, including submarines; adaptations to nuclear propulsion power plant or units for facilitating their arrangement on marine vessels
Nuclear spacecraft propulsion
Water treatment using waste heat from other processes
Methods and apparatus for obtaining oil, gas, water, soluble or meltable materials by means of nuclear energy
Aspects related to nuclear power plants in general, other than the reactor per se
Control of nuclear power plant
Arrangements of reactor and engine in which reactor-produced heat is converted into mechanical energy
Arrangements to provide heat for purposes other than conversion into power, e.g. heating buildings
Informative references
Attention is drawn to the following places, which may be of interest for search:
Pressure or containment vessels utilizing sub- or super-atmospheric pressure to effect chemical or physical change of matter
Cleaning pipes or tubes using methods or apparatus specially adapted thereto
Manipulators
Heat-transfer or heat-exchange or heat-storage materials
Shock-absorbers in general
Pressure vessels in general
Tube joints in general
Cleaning of internal or external surfaces of heat-exchange or heat-transfer conduits, e.g. water tubes of boilers
Measurement of nuclear radiation
Electric or magnetic analogue computers, e.g. simulators, for nuclear physics
Pumping arrangements for reactor coolant not otherwise covered by G21C 15/24
Shielded cells or rooms
Special rules of classification within this subclass

Classification of both important (invention) information and additional information is obligatory.

The following Indexing Codes do not follow the general ECLA/Indexing Code parallel scheme but are used to classify additional invention information for which an ECLA class is not available: G21C 2003/045, G21C 2003/047, G21C 2003/048, G21C 2003/3225, G21C 2003/3262, G21C 2003/3265, G21C 2003/3267, G21C 2015/185, G21C 2015/187. If appropriate, these Indexing Codes must be assigned if the corresponding ECLA subgroup is given, i.e. if either G21C 3/04, G21C 3/322, G21C 3/326 or G21C 15/18 is assigned.

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Core
The central region of a reactor containing fuel and moderator elements, where nuclear fission occurs.
Moderator
Material used in a thermal nuclear reactor to reduce the velocity of neutrons produced by nuclear fission in order to facilitate chain reaction.
Shield
Means surrounding a reactor to prevent radiation damage to operators etc.
Synonyms and Keywords

In patent documents the following abbreviations are often used:

LWR
Light Water Reactor
BWR
Boiling Water Reactor
ABWR
Advanced Boiling Water Reactor
PWR
Pressurized/Pressure Water Reactor
PHWR
Pressurized Heavy Water Reactor
RBMK
High Power Channel Reactor
GCR
Gas Cooled Reactor
HTGCR
High Temperature Gas Cooled Reactor
FBR
Fast Breeder Reactor
LMFBR
Liquid Metal Fast Breeder Reactor
PBR
Pebble Bed Reactor
IFR
Integral Fast Reactor
RPV
Reactor Pressure Vessel
CRDM
Control Rod Drive Mechanism
PCI
Pellet-Clad Interaction
LOCA
LOss of Coolant Accident

In patent documents the expressions/words "breed and burn reactor", "travelling wave reactor" and "deflagration wave reactor" are often used as synonyms.

Reactors
Definition statement
This subclass/group covers:

Nuclear fission reactors characterized by their type. Main division is made between fast neutron driven fission and moderated neutron drive fission reactors, the reactors being either critical or subcritical, loop-type or integral. Dedicated sections are defined for subcritical and integral reactors.

Further information:

Patent documents are generally covered by one of the main groups G21C 3/00 to G21C 23/00. Patent documents are covered also by G21C 1/00 only in case of subject-matter related to new reactor concepts or to specific subject-matter in which the type of reactor plays a crucial role for a complete definition of such subject-matter.

Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
References relevant to classification in this group
This subclass/group does not cover:
Core structures characterised by the provision of more than one active zone in which the core does not comprise fuel assemblies
Informative references
Attention is drawn to the following places, which may be of interest for search:
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:

In this group, the following terms or expressions are used with the meaning indicated:

Fuel rod, fuel pin, fuel element
Single fuel rod being part of bundle of fuel rods comprised in a fuel assembly
Fuel bundle
Fuel assembly
Fuel element
In some patent documents, in particular in those with German origin, this expression is sometimes used as meaning "fuel assembly"
Constructional details
Special rules of classification within this group

If related to fuel pellets, an appropriate Indexing Code amongst G21C 2003/045, G21C 2003/047 and G21C 2003/045 is also assigned.

Means to influence the coolant flow through or around the bundles
Special rules of classification within this group

If means to influence the coolant flow through/around the bundle by water rods, Indexing Code G21C 2003/3225 is also assigned.

comprising fuel elements of different composition; comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods
Special rules of classification within this group

If related to fuel assembly enrichment distribution in zones, an appropriate Indexing Code amongst G21C 2003/3262, G21C 2003/3265 and G21C 2003/3267 is also assigned.

Selection of substances for use as reactor fuel
Definition statement
This subclass/group covers:

This group covers all substances which are used as nuclear reactor fuel, either liquid or fluent nuclear fuel, gaseous compositions or solid nuclear reactor fuel.

References relevant to classification in this group
This subclass/group does not cover:
Nuclear fuel elements
Informative references
Attention is drawn to the following places, which may be of interest for search:
Obtaining metals with atomic number greater than 87
Synonyms and Keywords

In patent documents the following abbreviations are often used:

MOX
Mixed Oxide Fuel
Moderator or core structure; Selection of materials for use as moderator
Informative references
Attention is drawn to the following places, which may be of interest for search:
Shock absorbers per se
Active zone in which the core comprises fuel assemblies
Means for locating or supporting fuel elements [N: (means forming part of the element G21C 3/12)]
Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:

In this group the following expression is used with the meaning indicated:

Fuel element
fuel assembly
Control of nuclear reaction
References relevant to classification in this group
This subclass/group does not cover:
Control of nuclear power plant in general
Informative references
Attention is drawn to the following places, which may be of interest for search:
Boron and boron compounds per se
Ceramic materials per se
Alloys per se
Gearing in general
Safety arrangements for control of regulating systems in general
Control and regulating systems in general
Safety systems for the nuclear power plant in general
Neutron sources per se
Emergency protective circuit arrangements in general
Dynamo electric machines in general
Pulse techniques
Emergency protection arrangements structurally associated with the reactor, [N: e.g. safety valves provided with pressure equalisation devices] (emergency cooling arrangements G21C 15/18)
References relevant to classification in this group
This subclass/group does not cover:
Emergency cooling arrangements; removing shut-down heat
Safety systems of the nuclear power plant in general
Informative references
Attention is drawn to the following places, which may be of interest for search:
Processes and reactors using catalytically active bodies for gas/gas reactions
Blast shield in general
Recombiners in nuclear installations
Shielding structurally associated with the reactor
Informative references
Attention is drawn to the following places, which may be of interest for search:
Thermal insulation of pipes in general
Shielding in general
Pressure vessels; Containment vessels; Containment in general (for chemical or physical processes B01J 3/00; pressure vessels in general F16J 12/00)
the tube passing through the vessel wall, i.e. continuing on both sides of the wall
Definition statement
This subclass/group covers:

Repairing means and methods thereof.

References relevant to classification in this group
This subclass/group does not cover:
Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter and apparatus thereof, i.e. vessels for chemical or physical process
Pressure vessels in general
Vessels for storing gases
Informative references
Attention is drawn to the following places, which may be of interest for search:
Joints for pipes in general
Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
Informative references
Attention is drawn to the following places, which may be of interest for search:
Pumps in general
F04
Jet pumps per se
Ventilation means per se
Emergency protection arrangements strictly associated with the reactor, other than cooling
Safety arrangements of the nuclear power plant in general
Emergency cooling arrangements; Removing shut-down heat
Definition statement
This subclass/group covers:

Using passive systems, i.e. systems not requiring the use of active means such as pumps; examples: natural circulation; gravity.

[N: comprising powered means, e.g. pumps]
Definition statement
This subclass/group covers:

Using active means such as pumps.

Monitoring; Testing; (measuring in general G01); [N: Maintaining]
Definition statement
This subclass/group covers:

Monitoring/measuring/testing devices and methods strictly associated to nuclear fission reactors and their components.

Further information:

The subgroup G21C 17/06 also covers devices and methods for maintaining (e.g. cleaning) fuel elements or fuel assemblies.

References relevant to classification in this group
This subclass/group does not cover:
Safety arrangements for control of regulating systems in general
Monitoring or testing of control or regulating systems in general
Systems and methods, specially adapted for business purposes and their data processing
Electrical digital data processing
Time or attendance register; registering or indicating the working of machines
Informative references
Attention is drawn to the following places, which may be of interest for search:
Pipes in general
Pipes in steam generators
Arrangements for sealing leaking tubes and conduits in general
Measuring in general
G01
Measuring linear dimensions, angles, areas, irregularities of surfaces or contours
Investigating or analysing materials by determining their chemical or physical properties
Material analysis/investigation with ultrasonic, sonic or infrasonic waves
Investigating fluid tightness of structures
Measuring neutron radiation per se
Computer implemented systems and methods of testing, simulating and designing nuclear fission reactors or parts thereof
Arrangements for treating, for handling, or for facilitating the handling of, fuel or other materials which are used within the reactor, e.g. within its pressure vessel
Lifting devices or pulling devices adapted for co-operation with fuel elements or with control elements (manipulators B25J)
Definition statement
This subclass/group covers:

Loading and unloading of fuel assemblies to and from the reactor core.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Reprocessing of irradiated fuel
Storage rack for spent fuel casks
Treating/decontaminating radioactively contaminated materials
Reprocessing of irradiated fuel [N: In the groups G21C 19/42 to G21C 19/50, from 01-01-2003 onwards, new documents are classified according to the ECLA Reform approach, i.e. "invention information" is identified with classification symbols, e.g. G21C 19/46, while "additional information" is identified with Indexing Code symbols, e.g. G21C 19/46]
Definition statement
This subclass/group covers:

All aspects of the reprocessing of irradiated nuclear fuel, either aqueous or non-aqueous processes.

References relevant to classification in this group
This subclass/group does not cover:
Decommissioning of reactors
Informative references
Attention is drawn to the following places, which may be of interest for search:
Treating radioactively contaminated material
Synonyms and Keywords

In patent documents the following abbreviations are often used:

PUREX
Plutonium Uranium Refining by Extraction
COEX
Coextraction of Plutonium together with Uranium
Apparatus or processes specially adapted to the manufacture of reactors or parts thereof (in general section B, e.g. B23)
References relevant to classification in this group
This subclass/group does not cover:
Manufacture of spacer grids
Apparatus or processes for manufacturing in general
Section B, e.g. B23
Adaptations of reactors to facilitate experimentation or irradiation
Informative references
Attention is drawn to the following places, which may be of interest for search:
Irradiation loops in subcritical reactors
Arrangements for converting chemical elements by electromagnetic radiation in nuclear reactors
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Last Modified: 10/11/2013