G
SECTION G — PHYSICS
 G

Note(s)

  1. In this section, the following term is used with the meaning indicated:
    • "variable" (as a noun) means a feature or property (e.g., a dimension, a physical condition such as temperature, a quality such as density or colour) which, in respect of a particular entity (e.g., an object, a quantity of a substance, a beam of light) and at a particular instant, is capable of being measured; the variable may change, so that its numerical expression may assume different values at different times, in different conditions or in individual cases, but may be constant in respect of a particular entity in certain conditions or for practical purposes (e.g., the length of a bar may be regarded as constant for many purposes).
  2. Attention is drawn to the definitions of terms or expressions used, appearing in the notes of several of the classes in this section, in particular those of "measuring" in class G01 and "control" and "regulation" in class G05.
  3. Classification in this section may present more difficulty than in other sections, because the distinction between different fields of use rests to a considerable extent on differences in the intention of the user rather than on any constructional differences or differences in the manner of use, and because the subjects dealt with are often in effect systems or combinations, which have features or parts in common, rather than "things", which are readily distinguishable as a whole. For example, information (e.g., a set of figures) may be displayed for the purpose of education or advertising (G09), for enabling the result of a measurement to be known (G01), for signalling the information to a distant point or for giving information which has been signalled from a distant point (G08). The words used to describe the purpose depend on features that may be irrelevant to the form of the apparatus concerned, for example, such features as the desired effect on the person who sees the display, or whether the display is controlled from a remote point. Again, a device which responds to some change in a condition, e.g., in the pressure of a fluid, may be used, without modification of the device itself, to give information about the pressure (G01L) or about some other condition linked to the pressure (another subclass of class G01, e.g., G01K for temperature), to make a record of the pressure or of its occurrence (G07C), to give an alarm (G08B), or to control another apparatus (G05).

    The classification scheme is intended to enable things of a similar nature (as indicated above) to be classified together. It is therefore particularly necessary for the real nature of any technical subject to be decided before it can be properly classified.

  
NUCLEONICS
 G21
NUCLEAR PHYSICS; NUCLEAR ENGINEERING
 G21C
NUCLEAR REACTORS (analogue computers therefor G06G 7/54; fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
 G21C
Subclass index
REACTORS 1/00
REACTOR ELEMENTS
Fuel; moderator; cooling; containment; shielding 3/00; 5/00; 15/00; 13/00; 11/00
Handling fuel and other materials 19/00
CONTROL; MONITORING, TESTING 7/00; 17/00
EMERGENCY PROTECTION 9/00
MANUFACTURE 21/00
ADAPTATIONS OF REACTORS FOR EXPERIMENTATION OR IRRADIATION 23/00
P:40 G21C 1/00
Reactors
 G21C 1/01
·  General details not provided for in groups G21C 3/00-G21C 19/00  [3]
 G21C 1/02
·  Fast fission reactors, i.e. reactors not using a moderator
 G21C 1/03
·  ·  cooled by a coolant not essentially pressurised, e.g. pool-type reactors  [5]
 G21C 1/04
·  Thermal reactors
 G21C 1/06
·  ·  Heterogeneous reactors, i.e. in which fuel and moderator are separated
 G21C 1/07
·  ·  ·  Pebble-bed reactors; Reactors with granular fuel  [5]
 G21C 1/08
·  ·  ·  moderator being highly pressurised, e.g. boiling-water reactor, integral-superheat reactor, pressurised-water reactor (G21C 1/22 takes precedence)
 G21C 1/09
·  ·  ·  ·  Pressure regulating arrangements, i.e. pressurisers  [5]
 G21C 1/10
·  ·  ·  ·  moderator and coolant being different or separated
 G21C 1/12
·  ·  ·  ·  ·  moderator being solid, e.g. Magnox reactor
 G21C 1/14
·  ·  ·  moderator being substantially not pressurised, e.g. swimming-pool reactor (G21C 1/22 takes precedence)
 G21C 1/16
·  ·  ·  ·  moderator and coolant being different or separated, e.g. sodium-graphite reactor
 G21C 1/18
·  ·  ·  ·  ·  coolant being pressurised
 G21C 1/20
·  ·  ·  ·  ·  ·  moderator being liquid, e.g. pressure-tube reactor
 G21C 1/22
·  ·  ·  using liquid or gaseous fuel
 G21C 1/24
·  ·  Homogeneous reactors, i.e. in which fuel and moderator present an effectively homogeneous medium to the neutrons
 G21C 1/26
·  ·  ·  Single-region reactors
 G21C 1/28
·  ·  ·  Two-region reactors
 G21C 1/30
·  Subcritical reactors
 G21C 1/32
·  Integral reactors, i.e. reactors wherein parts functionally associated with the reactor but not essential to the reaction, e.g. heat exchangers, are disposed inside the enclosure with the core (G21C 1/02-G21C 1/30 take precedence)  [3]
P:70 G21C 3/00
Reactor fuel elements or their assemblies; Selection of substances for use as reactor fuel elements
 G21C 3/02
·  Fuel elements
 G21C 3/04
·  ·  Constructional details
 G21C 3/06
·  ·  ·  Casings; Jackets
 G21C 3/07
·  ·  ·  ·  characterised by their material, e.g. alloys  [5]
 G21C 3/08
·  ·  ·  ·  provided with external means to promote heat-transfer, e.g. fins, baffles, corrugations
 G21C 3/10
·  ·  ·  ·  End closures
 G21C 3/12
·  ·  ·  ·  Means forming part of the element for locating it within the reactor core; External spacers for this purpose
 G21C 3/14
·  ·  ·  ·  Means forming part of the element for inserting it into, or removing it from, the core; Means for coupling adjacent elements
 G21C 3/16
·  ·  ·  Details of the construction within the casing
 G21C 3/17
·  ·  ·  ·  Means for storage or immobilisation of gases in fuel elements  [5]
 G21C 3/18
·  ·  ·  ·  Internal spacers or other non-active material within the casing, e.g. compensating for expansion of fuel rods or for compensating excess reactivity (interlayers G21C 3/20)
 G21C 3/20
·  ·  ·  ·  with coating on fuel or on inside of casing; with non-active interlayer between casing and active material
 G21C 3/22
·  ·  with fissile or breeder material in contact with coolant
 G21C 3/24
·  ·  with fissile or breeder material in fluid form within a non-active casing
 G21C 3/26
·  ·  with fissile or breeder material in powder form within a non-active casing
 G21C 3/28
·  ·  with fissile or breeder material in solid form within a non-active casing
 G21C 3/30
·  Assemblies of a number of fuel elements in the form of a rigid unit
 G21C 3/32
·  ·  Bundles of parallel pin-, rod-, or tube-shaped fuel elements
 G21C 3/322
·  ·  ·  Means to influence the coolant flow through or around the bundles  [5]
 G21C 3/324
·  ·  ·  Coats or envelopes for the bundles  [5]
 G21C 3/326
·  ·  ·  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  [5]
 G21C 3/328
·  ·  ·  ·  Relative disposition of the elements in the bundle lattice  [5]
 G21C 3/33
·  ·  ·  Supporting or hanging of elements in the bundle (spacer grids G21C 3/34); Means forming part of the bundle for inserting it into, or removing it from, the core; Means for coupling adjacent bundles  [5]
 G21C 3/332
·  ·  ·  ·  Supports for spacer grids  [5]
 G21C 3/334
·  ·  ·  Assembling the bundles  [5]
 G21C 3/335
·  ·  ·  Exchanging elements in irradiated bundles  [5]
 G21C 3/336
·  ·  ·  Spacer elements for fuel rods in the bundle (spacer grids G21C 3/34)  [5]
 G21C 3/338
·  ·  ·  ·  Helicoidal spacer elements  [5]
 G21C 3/34
·  ·  ·  Spacer grids
 G21C 3/344
·  ·  ·  ·  formed of assembled tubular elements  [5]
 G21C 3/348
·  ·  ·  ·  formed of assembled non-intersecting strips  [5]
 G21C 3/352
·  ·  ·  ·  formed of assembled intersecting strips  [5]
 G21C 3/356
·  ·  ·  ·  being provided with fuel element supporting members  [5]
 G21C 3/36
·  ·  Assemblies of plate-shaped fuel elements or coaxial tubes
 G21C 3/38
·  Fuel units consisting of a single fuel element in a supporting sleeve
 G21C 3/40
·  Structural combination of fuel element with thermoelectric element for direct production of electric energy from fission heat (for temperature measurement G21C 17/10)
 G21C 3/42
·  Selection of substances for use as reactor fuel
 G21C 3/44
·  ·  Fluid or fluent reactor fuel
 G21C 3/46
·  ·  ·  Aqueous compositions
 G21C 3/48
·  ·  ·  ·  True or colloidal solutions of the active constituent
 G21C 3/50
·  ·  ·  ·  Suspensions of the active constituent; Slurries
 G21C 3/52
·  ·  ·  Liquid metal compositions
 G21C 3/54
·  ·  ·  Fused salt, oxide, or hydroxide compositions
 G21C 3/56
·  ·  ·  Gaseous compositions; Suspensions in a gaseous carrier
 G21C 3/58
·  ·  Solid reactor fuel
 G21C 3/60
·  ·  ·  Metallic fuel; Intermetallic dispersions
 G21C 3/62
·  ·  ·  Ceramic fuel
 G21C 3/64
·  ·  ·  ·  Ceramic dispersion fuel, e.g. cermet
P:100 G21C 5/00
Moderator or core structure; Selection of materials for use as moderator
 G21C 5/02
·  Details
 G21C 5/04
·  ·  Spatial arrangements allowing for Wigner growth
 G21C 5/06
·  ·  Means for locating or supporting fuel elements
 G21C 5/08
·  ·  Means for preventing undesired asymmetric expansion of the complete structure
 G21C 5/10
·  ·  Means for supporting the complete structure
 G21C 5/12
·  characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator
 G21C 5/14
·  characterised by shape
 G21C 5/16
·  ·  Shape of its constituent parts
 G21C 5/18
·  characterised by the provision of more than one active zone
 G21C 5/20
·  ·  wherein one zone contains fissile material and another zone contains breeder material
 G21C 5/22
·  ·  wherein one zone is a superheating zone
P:0 G21C 7/00
Control of nuclear reaction
 G21C 7/02
·  by using self-regulating properties of reactor materials (arrangements that involve temperature stability G21C 7/32)
 G21C 7/04
·  ·  of burnable poisons (burnable poisons in fuel rods G21C 3/326)  [5]
 G21C 7/06
·  by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
 G21C 7/08
·  ·  by displacement of solid control elements, e.g. control rods
 G21C 7/10
·  ·  ·  Construction of control elements
 G21C 7/103
·  ·  ·  ·  Control assemblies containing one or more absorbants as well as other elements, e.g. fuel or moderator elements  [5]
 G21C 7/107
·  ·  ·  ·  Control elements adapted for pebble-bed reactors  [5]
 G21C 7/11
·  ·  ·  ·  Deformable control elements, e.g. flexible, telescopic, articulated  [5]
 G21C 7/113
·  ·  ·  ·  Control elements made of flat elements; Control elements having cruciform cross-section  [5]
 G21C 7/117
·  ·  ·  ·  Clusters of control rods; Spider construction  [5]
 G21C 7/12
·  ·  ·  Means for moving control elements to desired position (dropping rods in an emergency G21C 9/02)
 G21C 7/14
·  ·  ·  ·  Mechanical drive arrangements
 G21C 7/16
·  ·  ·  ·  Hydraulic or pneumatic drive arrangements
 G21C 7/18
·  ·  ·  Means for obtaining differential movement of control elements
 G21C 7/20
·  ·  ·  Disposition of shock-absorbing devices (shock-absorbers in general F16F)
 G21C 7/22
·  ·  by displacement of a fluid or fluent neutron-absorbing material
 G21C 7/24
·  ·  Selection of substances for use as neutron-absorbing material
 G21C 7/26
·  by displacement of the moderator or parts thereof
 G21C 7/27
·  ·  Spectral shift control  [5]
 G21C 7/28
·  by displacement of the reflector or parts thereof
 G21C 7/30
·  by displacement of reactor fuel or fuel elements
 G21C 7/32
·  by varying flow of coolant through the core
 G21C 7/34
·  by utilisation of a primary neutron source
 G21C 7/36
·  Control circuits
P:30 G21C 9/00
Emergency protection arrangements structurally associated with the reactor (emergency cooling arrangements G21C 15/18)
 G21C 9/004
·  Pressure suppression  [5]
 G21C 9/008
·  ·  by rupture-discs or -diaphragms  [5]
 G21C 9/012
·  ·  by thermal accumulation or by steam condensation, e.g. ice condensers  [5]
 G21C 9/016
·  Core catchers  [5]
 G21C 9/02
·  Means for effecting very rapid reduction of the reactivity factor under fault conditions, e.g. reactor fuse
 G21C 9/027
·  ·  by fast movement of a solid, e.g. pebbles  [5]
 G21C 9/033
·  ·  by an absorbent fluid  [5]
 G21C 9/04
·  Means for suppressing fires
 G21C 9/06
·  ·  Means for preventing accumulation of explosives gases, e.g. recombiners  [5]
P:80 G21C 11/00
Shielding structurally associated with the reactor
 G21C 11/02
·  Biological shielding (in general G21F)
 G21C 11/04
·  ·  on waterborne craft
 G21C 11/06
·  Reflecting shields, i.e. for minimising loss of neutrons
 G21C 11/08
·  Thermal shields; Thermal linings, i.e. for dissipating heat from gamma radiation which would otherwise heat an outer biological shield
P:90 G21C 13/00
Pressure vessels; Containment vessels; Containment in general (for chemical or physical processes B01J 3/00; pressure vessels in general F16J 12/00)
 G21C 13/02
·  Details
 G21C 13/024
·  ·  Supporting constructions for pressure vessels or containment vessels  [5]
 G21C 13/028
·  ·  Seals, e.g. for pressure vessels or containment vessels  [5]
 G21C 13/032
·  ·  Joints between tubes and vessel walls, e.g. taking into account thermal stresses  [5]
 G21C 13/036
·  ·  ·  the tube passing through the vessel wall, i.e. continuing on both sides of the wall  [5]
 G21C 13/04
·  ·  Arrangements for expansion and contraction
 G21C 13/06
·  ·  Sealing-plugs (for pressure vessels in general F16J 13/00)
 G21C 13/067
·  ·  ·  for tubes, e.g. standpipes; Locking devices for plugs  [5]
 G21C 13/073
·  ·  ·  Closures for reactor-vessels, e.g. rotatable  [5]
 G21C 13/08
·  Vessels characterised by the material; Selection of materials for pressure vessels
 G21C 13/087
·  ·  Metallic vessels  [5]
 G21C 13/093
·  ·  Concrete vessels  [5]
 G21C 13/10
·  Means for preventing contamination in event of leakage
P:50 G21C 15/00
Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
 G21C 15/02
·  Arrangement or disposition of passages in which heat is transferred to the coolant, e.g. for coolant circulation through the supports of the fuel elements
 G21C 15/04
·  ·  from fissile or breeder material
 G21C 15/06
·  ·  ·  in fuel elements
 G21C 15/08
·  ·  from moderating material
 G21C 15/10
·  ·  from reflector or thermal shield
 G21C 15/12
·  ·  from pressure vessel; from containment vessel
 G21C 15/14
·  ·  from ducts conducting a hot fluid; from ducts comprising auxiliary apparatus, e.g. pumps, cameras
 G21C 15/16
·  comprising means for separating liquid and steam (separating in general B01D; steam traps F16T)
 G21C 15/18
·  Emergency cooling arrangements; Removing shut-down heat
 G21C 15/20
·  Partitions or thermal insulation between fuel channel and moderator, e.g. in pressure tube reactors
 G21C 15/22
·  Structural association of coolant tubes with headers or other pipes, e.g. in pressure tube reactors (joints of tubes in general F16L)  [4]
 G21C 15/24
·  Promoting flow of the coolant (electrodynamic pumps H02K 44/02)
 G21C 15/243
·  ·  for liquids  [5]
 G21C 15/247
·  ·  ·  for liquid metals  [5]
 G21C 15/25
·  ·  ·  using jet pumps  [5]
 G21C 15/253
·  ·  for gases, e.g. blowers  [5]
 G21C 15/257
·  ·  using heat-pipes  [5]
 G21C 15/26
·  ·  by convection, e.g. using chimneys, using divergent channels
 G21C 15/28
·  Selection of specific coolants (if serving as the moderator G21C 5/12; heat-transfer or heat-exchange materials C09K 5/00)
P:10 G21C 17/00
Monitoring; Testing (measuring in general G01)
 G21C 17/003
·  Remote inspection of vessels, e.g. pressure vessels  [5]
 G21C 17/007
·  ·  Inspection of the outer surfaces of vessels  [5]
 G21C 17/01
·  ·  Inspection of the inner surfaces of vessels  [5]
 G21C 17/013
·  ·  Inspection vehicles  [5]
 G21C 17/017
·  Inspection or maintenance of pipe-lines or tubes in nuclear installations  [5]
 G21C 17/02
·  Devices or arrangements for monitoring coolant or moderator
 G21C 17/022
·  ·  for monitoring liquid coolants or moderators  [5]
 G21C 17/025
·  ·  ·  for monitoring liquid metal coolants  [5]
 G21C 17/028
·  ·  for monitoring gaseous coolants  [5]
 G21C 17/032
·  ·  Reactor-coolant flow measuring or monitoring  [5]
 G21C 17/035
·  ·  Moderator- or coolant-level detecting devices  [5]
 G21C 17/038
·  ·  Boiling detection in moderator or coolant  [5]
 G21C 17/04
·  ·  Detecting burst slugs
 G21C 17/06
·  Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination (G21C 17/08, G21C 17/10 take precedence; detecting leaking fuel elements during reactor operation G21C 17/04)
 G21C 17/07
·  ·  Leak testing  [5]
 G21C 17/08
·  Structural combination of reactor core or moderator structure with viewing means, e.g. with television camera, periscope, window
 G21C 17/10
·  Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
 G21C 17/104
·  ·  Measuring reactivity  [5]
 G21C 17/108
·  ·  Measuring reactor flux  [5]
 G21C 17/112
·  ·  Measuring temperature  [5]
 G21C 17/116
·  ·  Passages or insulators, e.g. for electric cables  [5]
 G21C 17/12
·  ·  Sensitive element forming part of control element
 G21C 17/14
·  Period meters
P:60 G21C 19/00
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  [2]
 G21C 19/02
·  Details of handling arrangements
 G21C 19/04
·  ·  Means for controlling flow of coolant over objects being handled; Means for controlling flow of coolant through channel being serviced
 G21C 19/06
·  ·  Means for supporting or storing fuel elements or control elements  [4]
 G21C 19/07
·  ·  ·  Storage racks; Storage pools  [5]
 G21C 19/08
·  ·  Means for heating fuel elements before introduction into the core; Means for heating or cooling fuel elements after removal from the core
 G21C 19/10
·  ·  Lifting devices or pulling devices adapted for co-operation with fuel elements or with control elements (manipulators B25J)
 G21C 19/105
·  ·  ·  with grasping or spreading coupling elements  [5]
 G21C 19/11
·  ·  ·  with revolving coupling elements, e.g. socket coupling  [5]
 G21C 19/115
·  ·  ·  with latching devices and ball couplings  [5]
 G21C 19/12
·  ·  Arrangements for exerting direct hydraulic or pneumatic force on fuel element or on control element
 G21C 19/14
·  characterised by their adaptation for use with horizontal channels in the reactor core
 G21C 19/16
·  Articulated or telescopic chutes or tubes for connection to channels in the reactor core
 G21C 19/18
·  Apparatus for bringing fuel elements to the reactor charge area, e.g. from a storage place
 G21C 19/19
·  Reactor parts specifically adapted to facilitate handling, e.g. to facilitate charging or discharging of fuel elements  [3]
 G21C 19/20
·  Arrangements for introducing objects into the pressure vessel; Arrangements for handling objects within the pressure vessel; Arrangements for removing objects from the pressure vessel
 G21C 19/22
·  ·  Arrangements for obtaining access to the interior of a pressure vessel whilst the reactor is operating
 G21C 19/24
·  ·  ·  by using an auxiliary vessel which is temporarily sealed to the pressure vessel
 G21C 19/26
·  Arrangements for removing jammed or damaged fuel elements or control elements; Arrangements for moving broken parts thereof
 G21C 19/28
·  Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core (pumping coolant G21D)
 G21C 19/30
·  ·  with continuous purification of circulating fluent material, e.g. by extraction of fission products
 G21C 19/303
·  ·  ·  specially adapted for gases (decontamination of gases G21F 9/02)  [5]
 G21C 19/307
·  ·  ·  specially adapted for liquids (decontamination of liquids G21F 9/04)  [5]
 G21C 19/31
·  ·  ·  ·  for molten metals  [5]
 G21C 19/313
·  ·  ·  ·  ·  using cold traps  [5]
 G21C 19/317
·  ·  ·  Recombination devices for radiolytic dissociation products  [5]
 G21C 19/32
·  Apparatus for removing radioactive objects or materials from the reactor discharge area, e.g. to a storage place; Apparatus for handling radioactive objects or materials within a storage place or removing them therefrom (disposal of waste material G21F 9/00)
 G21C 19/33
·  Apparatus or processes for dismantling strings of spent fuel elements (G21C 19/34 takes precedence)  [2]
 G21C 19/34
·  Apparatus or processes for dismantling nuclear fuel, e.g. before reprocessing (shielded cells G21F 7/00)  [5]
 G21C 19/36
·  ·  Mechanical means only
 G21C 19/365
·  ·  ·  Removing cannings or casings from fuel  [5]
 G21C 19/37
·  ·  ·  ·  by separating into pieces both the canning or the casing and the fuel element, e.g. by cutting or shearing  [5]
 G21C 19/375
·  ·  ·  Compacting devices, e.g. for fuel assemblies  [5]
 G21C 19/38
·  ·  Chemical means only
 G21C 19/40
·  Arrangements for preventing occurrence of critical conditions, e.g. during storage
 G21C 19/42
·  Reprocessing of irradiated fuel
 G21C 19/44
·  ·  of irradiated solid fuel
 G21C 19/46
·  ·  ·  Aqueous processes
 G21C 19/48
·  ·  ·  Non-aqueous processes
 G21C 19/50
·  ·  of irradiated fluid fuel
P:110 G21C 21/00
Apparatus or processes specially adapted to the manufacture of reactors or parts thereof (in general, section B, e.g. B23)
 G21C 21/02
·  Manufacture of fuel elements or breeder elements contained in non-active casings
 G21C 21/04
·  ·  by vibrational compaction or tamping
 G21C 21/06
·  ·  by swaging
 G21C 21/08
·  ·  by a slip-fit cladding process
 G21C 21/10
·  ·  by extrusion, drawing, or stretching
 G21C 21/12
·  ·  by hydrostatic or thermo-pneumatic canning
 G21C 21/14
·  ·  by plating in a fluid
 G21C 21/16
·  ·  by casting or dipping techniques
 G21C 21/18
·  Manufacture of control elements covered by group G21C 7/00
P:20 G21C 23/00
Adaptations of reactors to facilitate experimentation or irradiation  [3]