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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 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 does not cover:

Nuclear fusion reactors

Treating radioactively contaminated materials; Decontamination arrangements therefor

Nuclear explosives and their application

Examples of places where the subject matter of this subclass is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

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, 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 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 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

Glossary of terms
In this 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 subgroup 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 subgroup 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 {(means forming part of the element G21C 3/12)}
Glossary of terms
In this subgroup, 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 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 {e.g. safety valves provided with pressure equalisation devices}(emergency cooling arrangements G21C 15/18)
References relevant to classification in this group
This 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

the tube passing through the vessel wall, i.e. continuing on both sides of the wall
Definition statement
This subgroup covers:

Repairing means and methods thereof.

References relevant to classification in this group
This subgroup 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

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 subgroup covers:

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

{comprising powered means, e.g. pumps}
Definition statement
This subgroup covers:

Using active means such as pumps.

Monitoring; Testing (measuring in general G01); { Maintaining}
Definition statement
This 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 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

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

Lifting devices or pulling devices adapted for co-operation with fuel elements or with control elements (manipulators B25J)
Definition statement
This subgroup 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
Definition statement
This subgroup covers:

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

References relevant to classification in this group
This subgroup 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 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