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 7/00; 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
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 3/30
·  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 3/326
·  ·  ·  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 3/33
·  ·  ·  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 3/34
·  ·  ·  Spacer grids
 G21C 3/42
·  Selection of substances for use as reactor fuel
P:100 G21C 5/00
Moderator or core structure; Selection of materials for use as moderator
P:0 G21C 7/00
Control of nuclear reaction
 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
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]
P:80 G21C 11/00
Shielding structurally associated with the reactor
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 13/08
·  Vessels characterised by the material; Selection of materials for pressure vessels
P:50 G21C 15/00
Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
 G21C 15/18
·  Emergency cooling arrangements; Removing shut-down heat
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 17/017
·  Inspection or maintenance of pipe-lines or tubes in nuclear installations  [5]
 G21C 17/02
·  Devices or arrangements for monitoring coolant or moderator
 G21C 17/06
·  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 17/02)
 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 17/14
·  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 19/20
·  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 19/28
·  Arrangements for introducing fluent material into the reactor core; Arrangements for removing fluent material from the reactor core (pumping coolant G21D)
 G21C 19/34
·  Apparatus or processes for dismantling nuclear fuel, e.g. before reprocessing (shielded cells G21F 7/00)  [5]
 G21C 19/42
·  Reprocessing of irradiated 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)
P:20 G21C 23/00
Adaptations of reactors to facilitate experimentation or irradiation  [3]