G21CNUCLEAR REACTORS fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21JThe following IPC groups are not in the CPC scheme. The subject matter for these IPC groups is classified in the following CPC groups: G21C19/33 covered by G21C19/34In this subclass non-limiting references (in the sense of paragraph 39 of the Guide to the IPC) may still be displayed in the scheme. G21C1/00 G21C1/00Reactor types G21C1/02Fast fission reactors, i.e. reactors not using a moderator ; Metal cooled reactors; Fast breeders G21C1/022characterised by the design or properties of the core G21C1/024where the core is divided in zones with fuel and zones with breeding material G21C1/026Reactors not needing refueling, i.e. reactors of the type breed-and-burn, e.g. travelling or deflagration wave reactors or seed-blanket reactors G21C1/028cooled by a pressurised coolant cooling arrangements G21C15/00 G21C1/03cooled by a coolant not essentially pressurised, e.g. pool-type reactors G21C1/04Thermal reactors ; Epithermal reactors G21C1/06Heterogeneous reactors, i.e. in which fuel and moderator are separated G21C1/07Pebble-bed reactorsReactors with granular fuel G21C1/08moderator being highly pressurised, e.g. boiling water reactor, integral super-heat reactor, pressurised water reactor G21C1/22 takes precedence G21C1/082Reactors where the coolant is overheated G21C1/084Boiling water reactors G21C1/086Pressurised water reactors G21C1/088Inherently safe boiling water reactors G21C1/09Pressure regulating arrangements, i.e. pressurisers G21C1/10moderator and coolant being different or separated G21C1/12moderator being solid, e.g. Magnox reactor or gas-graphite reactor G21C1/14moderator being substantially not pressurised, e.g. swimming-pool reactor G21C1/22 takes precedence G21C1/16moderator and coolant being different or separated, e.g. sodium-graphite reactor , sodium-heavy water reactor or organic coolant-heavy water reactor G21C1/18coolant being pressurised G21C1/20moderator being liquid, e.g. pressure-tube reactor G21C1/22using liquid or gaseous fuel G21C1/24Homogeneous reactors, i.e. in which the fuel and moderator present an effectively homogeneous medium to the neutrons G21C1/26Single-region reactors G21C1/28Two-region reactors G21C1/30Subcritical reactors ; Experimental reactors other than swimming-pool reactors or zero-energy reactors G21C1/303Experimental or irradiation arrangements inside the reactor irradiation loops G21C1/306 G21C1/306Irradiation loops G21C1/32Integral 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 G21C1/02 - G21C1/30 take precedence G21C1/322wherein the heat exchanger is disposed above the core G21C1/324wherein the heat exchanger is disposed beneath the core G21C1/326wherein the heat exchanger is disposed next to or beside the core G21C1/328wherein the prime mover is also disposed in the vessel G21C3/00Reactor fuel elements and their assembliesSelection of substances for use as reactor fuel elements G21C3/02Fuel elements manufacture thereof G21C21/02 G21C3/04Constructional details G21C3/041Means for removal of gases from fuel elements G21C3/042Fuel elements comprising casings with a mass of granular fuel with coolant passages through them G21C3/044Fuel elements with porous or capillary structure G21C3/045Pellets G21C3/047Pellet-clad interaction G21C3/048Shape of pellets G21C3/06CasingsJackets G21C3/07characterised by their material, e.g. alloys G21C3/08provided with external means to promote heat-transfer, e.g. fins, baffles G21C3/10End closures ; Means for tight mounting therefor G21C3/105Flattened end-closures G21C3/12Means forming part of the element for locating it within the reactor core means not forming part of the element G21C5/06 G21C3/14Means forming part of the element for inserting it into, or removing it from, the coreMeans for coupling adjacent elements , e.g. to form a stringer G21C3/16Details of the construction within the casing G21C3/17Means for storage or immobilisation of gases in fuel elements G21C3/18Internal spacers or other non-active material within the casing, e.g. compensating for expansion of fuel rods or for compensating excess reactivity interlayers G21C3/20 G21C3/20with coating on fuel or on inside of casingwith non-active interlayer between casing and active material with multiple casings or multiple active layers G21C3/22with fissile or breeder material in contact with coolant G21C3/24with fissile or breeder material in fluid form within a non-active casing G21C3/26with fissile or breeder material in powder form within a non-active casing G21C3/28with fissile or breeder material in solid form within a non-active casing G21C3/30Assemblies of a number of fuel elements in the form of a rigid unit G21C3/32Bundles of parallel pin-, rod-, or tube-shaped fuel elements G21C3/3206Means associated with the fuel bundle for filtering the coolant, e.g. nozzles, grids G21C3/3213Means for the storage or removal of fission gases means for the storage of fission gases in the elements G21C3/16; means for the removal of fission gases from elements G21C3/04 G21C3/322Means to influence the coolant flow through or around the bundles G21C3/3225by waterrods G21C3/324Coats or envelopes for the bundles G21C3/3245made of moderator material G21C3/326comprising fuel elements of different compositioncomprising, 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 G21C3/3262Enrichment distribution in zones G21C3/3265Radial distribution G21C3/3267Axial distribution G21C3/328Relative disposition of the elements in the bundle lattice G21C3/33Supporting or hanging of elements in the bundle spacer grids G21C3/34Means forming part of the bundle for inserting it into, or removing it from, the coreMeans for coupling adjacent bundles G21C3/3305Lower nozzle G21C3/331Comprising hold-down means, e.g. springs G21C3/3315Upper nozzle G21C3/332Supports for spacer grids G21C3/334Assembling , maintenance or repair of the bundles assembling, maintenance or repair of other reactor components G21C19/207 G21C3/335Exchanging elements in irradiated bundles G21C3/336Spacer elements for fuel rods in the bundle spacer grids G21C3/34 G21C3/338Helicoidal spacer elements G21C3/34Spacer grids G21C3/3408Compact spacer grids, e.g. made of a plate or a blade G21C3/3416Spacer grids formed by metallic wires, e.g. springs G21C3/3424Fabrication of spacer grids G21C3/3432Grids designed to influence the coolant, i.e. coolant mixing function G21C3/344formed of assembled tubular elements G21C3/348formed of assembled non-intersecting strips G21C3/352formed of assembled intersecting strips G21C3/356being provided with fuel element supporting members G21C3/3563Supporting members formed only by deformations in the strips G21C3/3566Supporting members formed only of elements fixed on the strips G21C3/36Assemblies of plate-shaped fuel elements or coaxial tubes G21C3/38Fuel units consisting of a single fuel element in a supporting sleeve or in another supporting element G21C3/40Structural combination of fuel element with thermoelectric element for direct production of electric energy from fission heat for temperature measurement G21C17/10 or with another arrangement for direct production of electric energy, e.g. a thermionic device combination with thermoelements for temperature measurements G21C17/102 G21C3/42Selection of substances for use as reactor fuel G21C3/44Fluid or fluent reactor fuel G21C3/46Aqueous compositions G21C3/48True or colloidal solutions of the active constituent G21C3/50Suspensions of the active constituentSlurries G21C3/52Liquid metal compositions G21C3/54Fused salt, oxide or hydroxide compositions G21C3/56Gaseous compositionsSuspensions in a gaseous carrier G21C3/58Solid reactor fuel Pellets made of fissile material G21C3/60Metallic fuelIntermetallic dispersions G21C3/62Ceramic fuel G21C3/623Oxide fuels G21C3/626Coated fuel particles G21C3/64Ceramic dispersion fuel, e.g. cermet G21C5/00Moderator or core structureSelection of materials for use as moderator G21C5/02Details G21C5/04Spatial arrangements allowing for Wigner growth G21C5/06Means for locating or supporting fuel elements means forming part of the element G21C3/12 G21C5/08Means for preventing undesired asymmetric expansion of the complete structure ; Stretching devices, pins G21C5/10Means for supporting the complete structure arrangements for supporting vessels and core-structures G21C13/024 G21C5/12characterised by composition, e.g. the moderator containing additional substances which ensure improved heat resistance of the moderator purification of fluid moderators during the operation of the reactor G21C19/30 G21C5/123Moderators made of organic materials G21C5/126Carbonic moderators carbon and graphite in general C01B32/00; refractory carbon-bulbs C04B35/00; carbon electrodes C25B G21C5/14characterised by shape G21C5/16Shape of its constituent parts G21C5/18characterised by the provision of more than one active zone G21C5/20wherein one zone contains fissile material and another zone contains breeder material G21C5/22wherein one zone is a superheating zone G21C7/00Control of nuclear reaction G21C7/005Flux flattening G21C7/02by using self-regulating properties of reactor materials, e.g. Doppler effectarrangements that involve temperature stability G21C7/32 G21C7/04of burnable poisons burnable poisons in fuel rods G21C3/326 G21C7/06by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section G21C7/08by displacement of solid control elements, e.g. control rods G21C7/10Construction of control elements G21C7/103Control assemblies containing one or more absorbants as well as other elements, e.g. fuel or moderator elements G21C7/107Control elements adapted for pebble-bed reactors G21C7/11Deformable control elements, e.g. flexible, telescopic, articulated G21C7/113Control elements made of flat elementsControl elements having cruciform cross-section G21C7/117Clusters of control rodsSpider construction G21C7/12Means for moving control elements to desired position dropping rods in an emergency G21C9/02 G21C7/14Mechanical drive arrangements G21C7/16Hydraulic or pneumatic drive G21C7/18Means for obtaining differential movement of control elements G21C7/20Disposition of shock-absorbing devices shock-absorbers in general F16F ; Braking arrangements G21C7/22by displacement of a fluid or fluent neutron-absorbing material , e.g. by adding neutron-absorbing material to the coolant G21C7/24Selection of substances for use as neutron-absorbing material G21C7/26by displacement of the moderator or parts thereof by changing the moderator concentration G21C7/27Spectral shift control G21C7/28by displacement of the reflector or parts thereof G21C7/30by displacement of the reactor fuel or fuel elements G21C7/32by varying flow of coolant through the core by adjusting the coolant or moderator temperature G21C7/34by utilisation of a primary neutron source G21C7/36Control circuits G21C9/00Emergency protection arrangements structurally associated with the reactor , e.g. safety valves provided with pressure equalisation devicesemergency cooling arrangements G21C15/18 G21C9/001against explosions, e.g. blast shields G21C9/002against Na- or Ka- reactions G21C9/004Pressure suppression G21C9/008by rupture-discs or -diaphragms G21C9/012by thermal accumulation or by steam condensation, e.g. ice condensers G21C9/016Core catchers G21C9/02Means for effecting very rapid reduction of the reactivity factor under fault conditions, e.g. reactor fuse; Control elements having arrangements activated in an emergencycontrol elements per se G21C7/00 G21C9/022Reactor fuses G21C9/024Rupture diaphragms G21C9/027by fast movement of a solid, e.g. pebbles G21C9/033by an absorbent fluid G21C9/04Means for suppressing fires Earthquake protection G21C9/06Means for preventing accumulation of explosives gases, e.g. recombiners G21C11/00Shielding structurally associated with the reactor G21C11/02Biological shielding in general G21F ; Neutron or gamma shielding G21C11/022inside the reactor vessel G21C11/024structurally combined with the casing G21C11/026in apertures or channels through a wall G21C11/028characterised by the form or by the material G21C11/04on waterborne craft G21C11/06Reflecting shields, i.e. for minimising loss of neutrons G21C11/08Thermal shieldsThermal linings, i.e. for dissipating heat from gamma radiation which would otherwise heat an outer biological shield Thermal insulation G21C11/081consisting of a non-metallic layer of insulating material G21C11/083consisting of one or more metallic layers G21C11/085consisting exclusively of several metallic layers G21C11/086consisting of a combination of non-metallic and metallic layers, e.g. metal-sand-metal-concrete G21C11/088consisting of a stagnant or a circulating fluid G21C13/00Pressure vesselsContainment vesselsContainment in general for chemical or physical processes B01J3/00; pressure vessels in general F16J12/00 G21C13/02Details G21C13/022Ventilating arrangements G21C13/024Supporting constructions for pressure vessels or containment vessels G21C13/028Seals, e.g. for pressure vessels or containment vessels G21C13/0285for container apertures G21C13/032Joints between tubes and vessel walls, e.g. taking into account thermal stresses G21C13/036the tube passing through the vessel wall, i.e. continuing on both sides of the wall G21C13/04Arrangements for expansion and contraction G21C13/06Sealing-plugs for pressure vessels in general F16J13/00 G21C13/063Seals for closures or for rotatable closures G21C13/067for tubes, e.g. standpipesLocking devices for plugs G21C13/0675Seals for the plugs G21C13/073Closures for reactor-vessels, e.g. rotatable G21C13/0735Seals for closures or for rotatable closures G21C13/08Vessels characterised by the materialSelection of materials for pressure vessels G21C13/087Metallic vessels G21C13/0875Tube-type vessels, e.g. for not essentially pressurised coolants G21C13/093Concrete vessels G21C13/0933made of prestressed concrete G21C13/0936Particulars concerning prestressing devices and cables G21C13/10Means for preventing contamination in the event of leakage, e.g. double wall G21C15/00Cooling arrangements within the pressure vessel containing the coreSelection of specific coolants G21C15/02Arrangements or disposition of passages in which heat is transferred to the coolant; Coolant flow control devices G21C19/04 takes precedence; coolant flow control through fuel assemblies, e.g. flow restrictors G21C3/322 G21C15/04from fissile or breeder material G21C3/32 takes precedence G21C15/06in fuel elements G21C15/08from moderating material G21C15/10from reflector or thermal shield G21C15/12from pressure vesselfrom containment vessel G21C15/14from headersfrom joints in ducts G21C15/16comprising means for separating liquid and steam separating in general B01D; steam traps F16D G21C15/18Emergency cooling arrangementsRemoving shut-down heat G21C15/182comprising powered means, e.g. pumps G21C15/185using energy stored in reactor system G21C15/187using energy from the electric grid G21C15/20Partitions or thermal insulation between fuel channel and moderator G21C15/22Structural association of coolant tubes with headers joints of tubes in general F16L G21C15/24Promoting flow of the coolant electrodynamic pumps H02K44/02 G21C15/243for liquids G21C15/247for liquid metals G21C15/25using jet pumps G21C15/253for gases, e.g. blowers G21C15/257using heat-pipes in general F28D, F28F G21C15/26by convection, e.g. using chimneys, using divergent channels G21C15/28Selection of specific coolants if serving as the moderator G21C5/12; compositions per se C09K5/00; organic coolants G21C5/123; Additions to the reactor coolants, e.g. against moderator corrosion purification and regeneration of the reactor coolants G21C19/30 G21C17/00MonitoringTesting measuring in general G01; Maintaining G21C17/001Mechanical simulators electrical or magnetic simulators G06G7/54 G21C17/002Detection of leaks by testing the coolant or the moderator G21C17/04 G21C17/003Remote inspection of vessels, e.g. pressure vessels G21C17/007Inspection of the outer surfaces of vessels G21C17/01Inspection of the inner surfaces of vessels G21C17/013Inspection vehicles G21C17/017Inspection or maintenance of pipe-lines or tubes in nuclear installations G21C17/02Devices or arrangements for monitoring coolant or moderator G21C17/021Solid moderators testing, e.g. graphite G21C17/022for monitoring liquid coolants or moderators G21C17/0225Chemical surface treatment, e.g. corrosion corrosion prevention in presence of water from scale removal or by modification of the properties of the liquid C02F5/00; inhibiting corrosion by adding corrosion inhibitors C23F11/00 G21C17/025for monitoring liquid metal coolants molten metal sampling in general G01N1/125 G21C17/0255Liquid metal leaks detection detecting leaks in pipe-line systems in general F17D5/00 G21C17/028for monitoring gaseous coolants G21C17/032Reactor-coolant flow measuring or monitoring measuring volume or mass flow in general G01F G21C17/035Moderator- or coolant-level detecting devices indicating or measuring liquid level in general G01F23/00 G21C17/038Boiling detection in moderator or coolant G21C17/04Detecting burst slugs G21C17/041characterised by systems for checking the coolant channels, e.g. matrix systems G21C17/042Devices for selective sampling, e.g. valves, shutters, rotatable selector valves G21C17/044Detectors and metering devices for the detection of fission products G21C17/045Precipitation chambers G21C17/047Detection and metering circuits G21C17/048characterised by a special construction of fuel elements, e.g. by a confined "tracer" G21C17/06Devices or arrangements for monitoring or testing fuel or fuel elements outside the reactor core, e.g. for burn-up, for contamination G21C17/08, G21C17/10 take precedence; detecting leaking fuel elements during reactor operation G21C17/04 G21C17/063Burn-up control G21C17/066 takes precedence G21C17/066Control of spherical elements G21C17/07Leak testing G21C17/08Structural combination of reactor core or moderator structure with viewing means, e.g. with television camera, periscope, window G21C17/10Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain G21C17/102the sensitive element being part of a fuel element or a fuel assembly structural combination with a thermoelectric element for direct production of electrical energy G21C3/40 G21C17/104Measuring reactivity G21C17/108Measuring reactor flux G21C17/112Measuring temperature G21C17/116Passages or insulators, e.g. for electric cables G21C17/12Sensitive element forming part of control element G21C17/14Period meters G21C19/00Arrangements 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 G21C19/02Details of handling arrangements G21C19/04Means for controlling flow of coolant over objects being handledMeans for controlling flow of coolant through channel being serviced , e.g. for preventing "blow-out" G21C19/06Magazines for holding fuel elements or control elements G21C19/065Rotatable magazines G21C19/07Storage racksStorage pools G21C19/08Means for heating fuel elements before introduction into the coreMeans for heating or cooling fuel elements after removal from the core G21C19/10Lifting devices or pulling devices adapted for co-operation with fuel elements or with control elements manipulators B25J G21C19/105with grasping or spreading coupling elements G21C19/11with revolving coupling elements, e.g. socket coupling G21C19/115with latching devices and ball couplings G21C19/12Arrangements for exerting direct hydraulic or pneumatic force on fuel element or on control element G21C19/14characterised by their adaptation for use with horizontal channels in the reactor core G21C19/16Articulated or telescopic chutes or tubes for connection to channels in the reactor core G21C19/18Apparatus for bringing fuel elements to the reactor charge area, e.g. from a storage place G21C19/19Reactor parts specifically adapted to facilitate handling, e.g. to facilitate charging or discharging of fuel elements G21C19/20Arrangements for introducing objects into the pressure vesselArrangements for handling objects within the pressure vesselArrangements for removing objects from the pressure vessel G21C19/202Arrangements for handling ball-form, i.e. pebble fuel G21C19/205Interchanging of fuel elements in the core, i.e. fuel shuffling G21C19/207Assembling, maintenance or repair of reactor components G21C3/334 takes precedence G21C19/22Arrangements for obtaining access to the interior of a pressure vessel whilst the reactor is operating G21C19/24by using an auxiliary vessel which is temporarily sealed to the pressure vessel G21C19/26Arrangements for removing jammed or damaged fuel elements or control elementsArrangements for moving broken parts thereof G21C19/28Arrangements for introducing fluent material into the reactor coreArrangements for removing fluent material from the reactor core pumping coolant G21D G21C19/30with continuous purification of circulating fluent material, e.g. by extraction of fission products deterioration or corrosion products, impurities, e.g. by cold traps purification of circulating fluid fuels G21C19/50; separation in general B01D G21C19/303specially adapted for gases decontamination of gases G21F9/02 G21C19/307specially adapted for liquids decontamination of liquids G21F9/04 G21C19/31for molten metals G21C19/313using cold traps G21C19/317Recombination devices for radiolytic dissociation products G21C19/32Apparatus for removing radioactive objects or materials from the reactor discharge area, e.g. to a storage placeApparatus for handling radioactive objects or materials within a storage place or removing them therefrom disposal of waste material G21F9/00 G21C19/34Apparatus or processes for dismantling nuclear fuel, e.g. before reprocessing ; Apparatus or processes for dismantling strings of spent fuel elementsshielded cells G21F7/00 G21C19/36Mechanical means only G21C19/365Removing cannings or casings from fuel G21C19/37by separating into pieces both the canning or the casing and the fuel element, e.g. by cutting or shearing G21C19/375Compacting devices, e.g. for fuel assemblies G21C19/38Chemical means only G21C19/40Arrangements for preventing occurrence of critical conditions, e.g. during storage G21C19/42Reprocessing of irradiated fuel G21C19/44of irradiated solid fuel G21C19/46Aqueous processes , e.g. by using organic extraction means, including the regeneration of these means G21C19/48Non-aqueous processes G21C19/50of irradiated fluid fuel , e.g. regeneration of fuels while the reactor is in operation G21C21/00Apparatus or processes specially adapted to the manufacture of reactors or parts thereof in general section B, e.g. B23 G21C21/02Manufacture of fuel elements or breeder elements contained in non-active casings G21C21/04by vibrational compaction or tamping of fuel in the jacket G21C21/06by rotatable swaging of the jacket around the fuel G21C21/08by a slip-fit cladding process by crimping the jacket around the fuel G21C21/10by extrusion, drawing, or stretching by rolling, e.g. "picture frame" technique G21C21/12by hydrostatic or thermo-pneumatic canning in general by pressing without lengthening, e.g. explosive coating G21C21/14by plating the fuel in a fluid G21C21/16by casting or dipping techniques G21C21/18Manufacture of control elements covered by group G21C7/00 G21C23/00Adaptations of reactors to facilitate experimentation or irradiation