Glossary

Every term this site uses to classify a record, and what each one does — and does not — mean. These are not decorative definitions: each is a controlled vocabulary id, and changing what a term means would change what the data says.

All 240 terms in the controlled vocabulary, every one of them defined. Where the sector routinely gets a term wrong — a regulatory stage that is not permission to build, a grant counted as equity, a plasma duration read as a confinement time — the definition says so explicitly.

Metrics 36

Capacity factor no records yet: Energy actually generated as a fraction of what continuous full-power operation would give. The number that separates a plant that runs from a plant that exists.; metric:capacity-factor
Capsule gain no records yet: Fusion energy divided by energy absorbed by the fuel capsule. Always larger than target gain — quoting it as 'the' gain overstates performance.; Total fusion energy yield ÷ Energy absorbed by the capsule; metric:gain-capsule
Core outlet temperature no records yet: Sets which industrial heat applications a design can serve.; metric:core-outlet-temperature
Cumulative funding raised no records yet: DERIVED by summing deals — never hand-entered. This is what makes '$65M+' and '~$8.94M across 3 rounds' impossible to write down.; metric:cumulative-funding
Electron temperature no records yet: Electron temperature. Distinct from ion temperature and usually lower in the plasmas that matter here; fusion rate depends on the ions, so quoting electron temperature as "the" temperature overstates nothing but answers a different question.; metric:electron-temperature
Energy confinement time (τ_E) 22 records: How long the plasma retains its energy (τ_E) — stored energy divided by heating power. NOT the length of the discharge: a machine can hold a plasma for 1,000 seconds with a confinement time of a fraction of a second, and conflating the two is one of the most common errors in coverage.; metric:energy-confinement-time
Engineering gain (Q_eng) Q_eng no records yet: Net electrical output divided by total electrical input, recirculating power included. No device has exceeded zero.; Gross electrical output ÷ Total electrical input including all plant recirculating power; metric:gain-engineering
Equivalent D-T gain (extrapolated) 1 record: Gain a D-D or D-³He shot WOULD have reached had it run on D-T. A calculation, never a measurement. Requires conditions.isSimulated = true and is excluded from achieved leaderboards.; Modelled D-T fusion power ÷ External heating power coupled into the plasma; metric:gain-equivalent
Fuel enrichment no records yet: Percentage of fissile isotope in the fuel. Above 5% and up to 20% is HALEU, which most advanced designs need and for which Western supply is currently thin.; metric:fuel-enrichment
Fusion energy yield 2 records: Total fusion energy released in one shot or pulse. A numerator only — on its own it says nothing about the energy required to produce it. See gain.; metric:fusion-energy-yield
Fusion power no records yet: Thermal power released by fusion reactions. A rate, not a total; the total released in one pulse is fusion energy yield.; metric:fusion-power
Fusion triple product (nTτ_E) nTτ 23 records: Density × ion temperature × energy confinement time. The fairest single comparator across confinement approaches.; metric:triple-product
Headcount no records yet: Employees. A rough proxy for scale, and one of the few figures a private company reliably discloses.; metric:headcount
HTS tape critical current no records yet: Meaningless without conditions — record temperature and applied field in conditions.; metric:hts-critical-current
Ion temperature 23 records: Record with qualifier peak or sustained — they are different achievements and conflating them is a listed red flag.; metric:ion-temperature
Laser energy on target 1 record: Laser energy delivered on target. The denominator of target gain. The energy drawn from the grid to produce it is far larger, which is why wall-plug gain differs from target gain by orders of magnitude.; metric:laser-energy
Lawson parameter (nτ_E) no records yet: Density × energy confinement time (nτ_E). The Lawson criterion in its original form, before temperature was folded in to give the triple product.; metric:lawson-parameter
Levelised cost of energy no records yet: Levelised cost of energy — lifetime cost divided by lifetime output. Highly sensitive to discount rate, capacity factor and build time, so two LCOE figures are rarely comparable unless all three assumptions are stated.; metric:lcoe
Major radius R0 60 records: Distance from the torus axis to the plasma centre. A design parameter of the machine, not a shot result.; metric:major-radius
Minor radius a 60 records: Plasma cross-section radius. Design parameter.; metric:minor-radius
Net electrical capacity no records yet: Net electrical output to the grid, after the plant’s own consumption. Distinct from thermal capacity, and lower — typically by a factor of about three.; metric:electrical-capacity
Neutron yield per shot no records yet: Neutrons produced per shot. For D-T, roughly 80% of the energy leaves as 14.1 MeV neutrons, so neutron yield is often the most direct measurement of how much fusion actually occurred.; metric:neutron-yield
On-axis magnetic field 60 records: Toroidal field strength at the plasma magnetic axis (B₀). A design parameter of the machine, not something achieved on a shot. Peak field on the coil is higher and is recorded separately.; metric:magnetic-field-onaxis
Overnight capital cost no records yet: Build cost excluding financing, as if the plant appeared overnight. Widely quoted because it is flattering: real projects pay interest for a decade of construction, and that is where nuclear economics is usually decided.; metric:overnight-capital-cost
Patent families no records yet: Distinct inventions patented, counting one family rather than each national filing. Filing counts inflate the same invention many times over.; metric:patent-families
Peak field on coil no records yet: The highest field anywhere on the magnet, which is what the conductor and structure must survive. Always higher than the on-axis field quoted for the plasma, and the two are not interchangeable.; metric:magnetic-field-peak-coil
Plasma current 60 records: Current driven through the plasma (Iₚ). In a tokamak it generates the poloidal field confinement depends on; a stellarator produces that field from its coils and needs none.; metric:plasma-current
Plasma density 19 records: Number of particles per cubic metre. Fusion rate scales with the square of density, which is why it appears in both the Lawson parameter and the triple product.; metric:plasma-density
Plasma duration 45 records: Wall-clock length of a sustained discharge. Distinct from confinement time, and routinely confused with it in press coverage.; metric:plasma-duration
Plasma gain (Q_plasma) Q_plasma 4 records: Fusion power divided by external heating power coupled into the plasma. The magnetic-confinement counterpart of target gain.; Fusion power produced ÷ External heating power coupled into the plasma; metric:gain-plasma
Refuelling interval no records yet: How long the reactor runs before refuelling. A headline advantage of many small designs, and a claim that only becomes a fact once a reactor has run that long.; metric:refuelling-interval
Repetition rate no records yet: Shots per second. The metric that separates a physics demonstration from a power plant.; metric:repetition-rate
Target gain (Q_target) Q_target 2 records: Fusion energy released divided by laser energy delivered to the target assembly.; Total fusion energy yield of the implosion ÷ Laser energy delivered to the target, including hohlraum losses; metric:gain-target
Thermal capacity no records yet: Heat produced by the reactor core. Roughly three times the electrical capacity for a steam-cycle plant; quoting thermal figures where a reader expects electrical inflates the number without stating an untruth.; metric:thermal-capacity
Tritium breeding ratio no records yet: Must exceed 1 for a D-T plant to be self-sufficient. Almost always modelled rather than measured — check conditions.isSimulated.; metric:tritium-breeding-ratio
Wall-plug gain 1 record: Fusion energy released divided by total facility energy drawn from the grid for the shot. The number that is almost never quoted, and typically two to three orders of magnitude below target gain.; Total fusion energy yield ÷ Total facility grid energy drawn for the shot; metric:gain-wallplug

Technology approaches 34

Beam-target 3 records: Net-energy-incapable by construction, but commercially relevant for neutron and isotope production.; approach:beam-target
Boiling water reactor BWR 1 record: Water boils directly in the core and the steam drives the turbine — one loop instead of two, simpler but with an activated steam circuit.; approach:bwr
Electrostatic confinement no records yet: Confinement by electric rather than magnetic fields.; approach:electrostatic
Field-reversed configuration FRC 2 records: A self-organised plasma ring that generates its own confining field, with no central coil. Compact and high-beta, but stability over long timescales is the open question.; approach:frc
Fission no records yet: Energy released by splitting heavy nuclei. Every operating nuclear power station works this way; every fusion device in this dataset does not.; approach:fission
Fluoride salt-cooled high-temperature reactor FHR 1 record: Molten salt COOLANT with solid fuel, typically TRISO. Kairos Power's KP-FHR is the reference example. Added in wave w001 after the original vocabulary forced it into approach:molten-salt, which was wrong.; approach:fhr
Fusion 34 records: Umbrella term used only where a record’s specific confinement approach is not established by evidence. A narrower term is always preferred when the sources support one.; approach:fusion
Gas-cooled no records yet: Reactors cooled by gas — usually helium or carbon dioxide — allowing higher outlet temperatures than water.; approach:gas-cooled
Heat-pipe microreactor 2 records: Heat moved by sealed heat pipes rather than pumped coolant. No primary pumps and no coolant loop, which suits very small transportable reactors.; approach:heat-pipe
Heavy-ion ICF no records yet: Heavy ion beams rather than lasers deliver the compression energy. Accelerators are efficient and repeat readily, which lasers of this scale do not.; approach:icf-heavy-ion
High-temperature gas-cooled reactor HTGR 7 records: Helium-cooled and graphite-moderated, running far hotter than a water reactor. The high outlet temperature suits industrial process heat as well as electricity.; approach:htgr
Inertial confinement ICF 7 records: Compressing fuel so fast that its own inertia holds it together long enough to burn — nanoseconds, not seconds.; approach:inertial-confinement
Inertial electrostatic confinement 2 records: Electric fields rather than magnetic ones confine the ions. Simple to build and well proven as a neutron source; net energy is a different matter.; approach:iec
Laser ICF, direct drive 7 records: Laser beams strike the fuel capsule directly. More efficient than indirect drive in principle, but far more sensitive to how evenly the beams are applied.; approach:icf-laser-direct
Laser ICF, indirect drive 4 records: Laser energy converted to X-rays in a hohlraum, which drives the capsule. The NIF configuration.; approach:icf-laser-indirect
Lead fast reactor LFR 2 records: Molten lead or lead-bismuth coolant, fast spectrum. Chemically inert with water and air, unlike sodium, at the cost of weight and corrosion engineering.; approach:lfr
Levitated dipole 1 record: Confinement around a single magnetically levitated superconducting ring, modelled on how planetary magnetospheres hold plasma.; approach:levitated-dipole
Liquid-metal cooled no records yet: Reactors cooled by molten metal, enabling a fast neutron spectrum at near-atmospheric pressure.; approach:liquid-metal
Magnetic confinement MCF no records yet: Holding a hot plasma away from material walls using magnetic fields, for seconds to steady-state.; approach:magnetic-confinement
Magnetic mirror 2 records: Plasma trapped between two regions of strong magnetic field that reflect particles back. Simple and linear, but historically leaky at the ends.; approach:mirror
Magnetized target 2 records: A magnetised plasma target compressed mechanically or by an imploding liner. Sits between magnetic and inertial confinement in density and timescale.; approach:magnetized-target
Magneto-inertial 3 records: Compression of a magnetised plasma; sits between MCF and ICF in density and timescale.; approach:magneto-inertial
Molten salt reactor MSR 9 records: Fuel DISSOLVED in the salt. Distinct from a salt-cooled reactor with solid fuel — conflating the two is the most common advanced-nuclear classification error.; approach:molten-salt
Pressurised water reactor PWR 9 records: Water kept under high pressure so it heats without boiling, transferring heat to a separate steam loop. The most common reactor type in service worldwide.; approach:pwr
Projectile-driven 1 record: A physical projectile accelerated to extreme velocity compresses the fuel on impact.; approach:projectile-driven
Pulsed magnetic compression 1 record: Repeated compression of a plasma by pulsed magnetic fields, recovering energy directly from the expansion rather than through a steam cycle.; approach:pulsed-magnetic-compression
Reversed-field pinch 1 record: A toroidal configuration where the field reverses direction at the plasma edge, allowing confinement at much lower external field than a tokamak.; approach:reversed-field-pinch
Salt-based no records yet: Reactors using molten salt as fuel carrier, coolant, or both.; approach:salt-based
Sodium fast reactor SFR 4 records: Liquid sodium coolant with a fast neutron spectrum. Sodium carries heat superbly at atmospheric pressure, but burns in air and reacts violently with water.; approach:sfr
Spherical tokamak 8 records: A tokamak squeezed towards a cored-apple shape. The tighter aspect ratio holds plasma pressure with less magnetic field, which is efficient — but leaves very little room at the centre for the central column.; approach:spherical-tokamak
Stellarator 21 records: Confinement produced entirely by external coils twisted into complex three-dimensional shapes, with no current driven through the plasma. Far harder to build than a tokamak and inherently steady-state rather than pulsed.; approach:stellarator
Tokamak 60 records: Doughnut-shaped magnetic confinement using a strong toroidal field plus a current driven through the plasma itself. The most-studied configuration, and the one ITER uses.; approach:tokamak
Water-cooled no records yet: Reactors using ordinary or heavy water as both coolant and neutron moderator.; approach:water-cooled
Z-pinch 4 records: A current driven straight through a plasma column, whose own magnetic field squeezes it inward. Long dismissed as unstable; sheared-flow stabilisation revived it.; approach:z-pinch

Categories 22

Breeding blanket no records yet: The breeding blanket, which absorbs neutrons to make tritium and capture heat. No commercial-scale blanket has ever operated, and without one D-T fusion has no fuel supply.; cat:blanket
Cryogenics no records yet: Cooling to superconducting temperatures, and the plant that sustains it. Superconducting magnets are only an advantage if the cryoplant works.; cat:cryogenics
Diagnostics no records yet: Instruments that measure what the plasma is doing. Every number in this benchmark exists because a diagnostic produced it.; cat:diagnostics
Divertor no records yet: The component that exhausts heat and helium ash from the plasma edge. Steady-state heat fluxes there rival a rocket nozzle.; cat:divertor
Enrichment no records yet: Raising the fissile fraction of uranium. The chokepoint of the fission fuel cycle, and the step with the heaviest non-proliferation constraints.; cat:enrichment
Gyrotron no records yet: High-power microwave sources for electron-cyclotron heating. A specialist supply chain with very few vendors worldwide.; cat:gyrotron
Heating and current drive no records yet: Systems that heat the plasma and drive current in it — microwaves, neutral beams, radiofrequency.; cat:heating-current-drive
HTS tape no records yet: REBCO and related high-temperature superconducting tape. The binding supply constraint for high-field tokamak programmes.; cat:hts-tape
ICF targets no records yet: Fuel capsules for inertial confinement. A power plant would need several a second; the current world supply is measured in hundreds a year.; cat:targets
Lasers and optics no records yet: Laser drivers and optics. For inertial confinement the laser IS the machine, and its wall-plug efficiency sets the ceiling on any plant.; cat:lasers
Magnets no records yet: Magnet systems that confine the plasma. The dominant cost and engineering risk in most magnetic-confinement designs.; cat:magnets
Neutral beam injector no records yet: Injectors that heat plasma by firing energetic neutral atoms into it, which cross the magnetic field because they carry no charge.; cat:neutral-beam
Plasma-facing components no records yet: Components that face the plasma directly and take the heat and particle flux — the hardest materials problem in fusion.; cat:plasma-facing
Power conversion no records yet: Turning heat into electricity — turbines, generators, heat exchangers, steam or gas cycles.; cat:power-conversion
Pulsed power no records yet: Capacitor banks and switching that deliver enormous energy in microseconds, used by z-pinch and inertial approaches.; cat:pulsed-power
Remote handling and robotics no records yet: Remote handling and maintenance. Once a machine is activated, everything inside it must be serviced without a human present.; cat:robotics
Simulation and modelling no records yet: Modelling of plasmas, neutronics, materials and whole plants. Cheaper than experiments, and never a substitute for one.; cat:simulation
Structural and irradiation-tolerant materials no records yet: Structures that survive 14 MeV neutron damage without unacceptable swelling, embrittlement or long-lived activation.; cat:structural-materials
TRISO fuel no records yet: Tri-structural isotropic fuel: fissile kernels in ceramic coatings that retain fission products at high temperature. The safety case for several advanced designs rests on it.; cat:triso-fuel
Tritium handling no records yet: Storage, recovery and accounting for tritium. It is radioactive, mobile, expensive, and the world civil inventory is small enough to constrain the whole sector.; cat:tritium-handling
Used fuel and waste management no records yet: Spent fuel storage, reprocessing and waste management — the part of the fuel cycle no design escapes.; cat:used-fuel
Vacuum systems no records yet: Vacuum vessels, pumps and seals. A fusion device is among the largest high-vacuum systems ever built.; cat:vacuum

Regulatory stages 15

Accepted for review no records yet: The regulator has accepted an application for review — "docketing". It means the paperwork is complete enough to examine, and says nothing about whether it will be approved.; regstage:application-accepted
Application denied 1 record: Terminal for that application. Kept visible — denials are as informative as approvals and are routinely omitted from company timelines.; regstage:application-denied
Application submitted 2 records: An application has been filed with the regulator. Filing is not acceptance, review, or approval, and applications are regularly withdrawn.; regstage:application-submitted
Application withdrawn no records yet: The applicant withdrew before a decision. Recorded as a first-class outcome — withdrawals and denials disappear from most trackers, which biases every remaining figure.; regstage:application-withdrawn
Commercial operation no records yet: Declared commercially operational, after commissioning tests are complete. The end of the regulatory sequence and the start of the economic one.; regstage:commercial-operation
Construction permit issued 1 record: The regulator has authorised construction at a named site. The strongest pre-construction stage, and distinct from design approval, which is site-independent.; regstage:construction-permit-issued
Construction start no records yet: Physical construction has begun. Distinct from holding a permit that allows it.; regstage:construction-start
Design approval or certification 2 records: The regulator has approved or certified a design. This is NOT permission to build: a site licence or construction permit is a separate and additional step. Coverage describing design approval as "approved to build" is the most common regulatory error in this sector.; regstage:design-approval
First criticality 1 record: The reactor first sustained a chain reaction — the moment a design becomes an operating plant.; regstage:first-criticality
Fuel load no records yet: Fuel loaded into the reactor for the first time. Irreversible in practice: the plant is radioactive from here on.; regstage:fuel-load
Grid connection no records yet: First delivery of electricity to the grid. Frequently reported as "operational", though full commercial operation usually follows months later.; regstage:grid-connection
Operating licence issued no records yet: Permission to operate granted. The point at which a built plant may actually run.; regstage:operating-licence-issued
Operating licence submitted no records yet: An application to operate has been filed, typically after construction is under way.; regstage:operating-licence-submitted
Pre-application engagement no records yet: Talking to the regulator before filing anything. No application exists. Coverage describing this as engagement with the regulator is accurate; describing it as progress toward approval is not.; regstage:pre-application
Safety review complete no records yet: The regulator has finished its technical safety evaluation. A major milestone, and still not permission to build.; regstage:safety-review-complete

Relationship types 14

Acquired no records yet: Bought another organisation.; reltype:acquired
Collaborates with no records yet: Works jointly on research or development, typically without a commercial contract.; reltype:collaborates-with
Customer of no records yet: Buys from another organisation.; reltype:customer-of
Employs no records yet: Employs a named person.; reltype:employs
Licensee of no records yet: Holds a licence to another organisation’s technology.; reltype:licensee-of
Member of no records yet: Belongs to a consortium, association or programme.; reltype:member-of
Offtaker of no records yet: Has contracted to buy future output.; reltype:offtaker-of
Operates no records yet: Runs a facility, which may have been built or owned by someone else.; reltype:operates
Owns no records yet: Holds ownership of a facility or asset.; reltype:owns
Partner with no records yet: A stated collaboration between organisations, symmetric by definition.; reltype:partner-with
Regulates no records yet: Holds regulatory authority over another organisation.; reltype:regulates
Spun out of no records yet: Was founded out of a university, laboratory or company. Common in this sector and frequently the origin of the technology.; reltype:spun-out-of
Subsidiary of no records yet: Is majority-owned and controlled by another organisation.; reltype:subsidiary-of
Supplies no records yet: Provides components, materials or services to another organisation.; reltype:supplies

Roles 14

Consortium 9 records: A multi-party body pooling funding or facilities across organisations or states — ITER being the largest example.; role:consortium
Fusion developer 56 records: Develops a fusion device or power plant concept. Carries no implication that the device exists or works.; role:fusion-developer
Government programme 7 records: A state programme rather than a company: the funder, operator or coordinator of a national effort.; role:government-programme
Investor 6 records: Provides capital. Held as a role on the organisation rather than in a separate collection, so one record can be both investor and operator.; role:investor
National laboratory 12 records: A state-funded laboratory operating at national scale, usually running facilities no single university could support.; role:national-lab
Offtaker 2 records: Contracted buyer of future output — the role Microsoft occupies with Helion.; role:offtaker
Operator 60 records: Runs a facility, which may have been built by someone else.; role:operator
Reactor developer 41 records: Develops a fission reactor design. Carries no implication that anything is licensed, funded or built.; role:reactor-developer
Regulator 2 records: Regulators are Organizations so that dockets resolve to a page and to a citable body.; role:regulator
Research institute 41 records: A public or non-profit research body. Frequently operates devices it did not commercially develop.; role:research-institute
Supplier 60 records: Supplies components, materials or fuel to the sector without developing a reactor or device of its own.; role:supplier
Unclassified 4 records: Discovered and captured, but not yet classified. Carries no claim about what the organization does. The autonomous discovery loop lands stubs with this role rather than guessing a real one — a wrong role is a false assertion, while an explicit 'we have not looked yet' is true. Records holding it are excluded from every sector listing and leaderboard until reclassified.; role:unclassified
University 29 records: A degree-granting institution. Many of the smaller devices in this dataset are university machines.; role:university
Utility 10 records: Generates or distributes electricity. Buys, operates or offtakes from plants rather than designing them.; role:utility

Funding instruments 12

Acquisition no records yet: Purchase of one organisation by another.; instr:acquisition
Convertible note or SAFE no records yet: A loan that may convert to equity later. Neither purely debt nor equity until it converts.; instr:convertible
Debt no records yet: Borrowed money, repayable with interest.; instr:debt
Equity round 1 record: Capital raised in exchange for ownership. The only instrument that dilutes existing holders, and the one most often reported as "raised".; instr:equity-round
Grant no records yet: Non-dilutive money that need not be repaid, usually public. Adding grants to equity and calling the sum "total raised" is the most common error in fusion funding figures.; instr:grant
In-kind contribution no records yet: How most ITER-party contributions are actually made.; instr:in-kind
IPO no records yet: First sale of shares to the public.; instr:ipo
Loan guarantee no records yet: A government promise to cover a lender if the borrower defaults. Not cash received, and counting it as funding raised overstates a balance sheet substantially.; instr:loan-guarantee
Milestone-based award 1 record: Paid against delivered technical milestones. The DOE fusion programme's mechanism, and structurally unlike a VC round.; instr:milestone-award
Offtake or power purchase agreement 1 record: Commits capacity, not cash. Recording it as a funding round would overstate capital raised.; instr:offtake-ppa
Prize no records yet: An award won competitively, usually for a demonstrated result.; instr:prize
SPAC merger 1 record: Listing by merger with a shell company already on an exchange. Faster than an IPO and historically associated with more optimistic projections.; instr:spac

Lifecycle status 11

Acquired no records yet: Bought by another organisation. The record is retained, with the acquirer named, because history does not stop at acquisition.; status:acquired
Active 60 records: The organisation is trading or operating. This says nothing about whether its technology works — an active company may have built nothing.; status:active
Cancelled no records yet: Abandoned before completion. A first-class outcome in this dataset, not an absence of one.; status:cancelled
Commissioning no records yet: Built, and being brought into operation. Between construction and operating, and frequently the longest phase.; status:commissioning
Decommissioned no records yet: Permanently shut down and being dismantled.; status:decommissioned
Defunct no records yet: Ceased to exist. The record stays: a directory that quietly deletes failures overstates the sector’s success rate.; status:defunct
Operating 60 records: The facility is running. For a device this means it produces plasma or is critical, not merely that the building stands.; status:operating
Planned 4 records: Announced or designed, but not under construction. Permanently ineligible for achievement leaderboards: a target is not a result.; status:planned
Shut down 14 records: Permanently ceased operation. The record is kept rather than deleted — the history is part of the evidence.; status:shutdown
Stealth no records yet: Operating without public disclosure of what it is doing. Recorded when existence is established but activity is not.; status:stealth
Under construction 6 records: Physical construction has begun on site. Distinct from a construction permit, which is permission to begin and often precedes the first concrete by years.; status:construction

Product types 11

Component no records yet: A discrete part supplied into someone else’s system: a magnet, a valve, a vacuum vessel.; ptype:component
Energy offtake no records yet: A contract to buy future output. The buyer is taking a position on a plant existing, which is why offtakes are tracked as deals rather than as revenue.; ptype:energy-offtake
Fuel no records yet: Fuel as a product: TRISO pebbles, fuel assemblies, tritium, deuterium.; ptype:fuel
Instrument or diagnostic no records yet: Diagnostic or measurement equipment, from neutron detectors to interferometers.; ptype:instrument
Isotope or radiopharmaceutical no records yet: Near-term revenue for several fusion-adjacent firms, and often the real business model behind a fusion roadmap.; ptype:isotope
Material no records yet: A material supplied as such — lithium, beryllium, tungsten, HTS tape, structural steel.; ptype:material
Power plant design no records yet: A complete plant concept, of which instances may be built. The design is the Product; a plant built from it is a Facility.; ptype:power-plant-design
Reactor module no records yet: A factory-built reactor unit intended to be shipped and installed rather than constructed on site — the central premise of the SMR case.; ptype:reactor-module
Service no records yet: Work sold rather than a thing: engineering, testing, irradiation, decommissioning, consultancy.; ptype:service
Software no records yet: Simulation, control or analysis software sold or licensed as a product.; ptype:software
Subsystem no records yet: An integrated assembly performing a function — a heating system, a divertor, a fuel-handling plant.; ptype:subsystem

Investor types 9

Angel no records yet: An individual investing personally.; invtype:angel
Corporate venture no records yet: A corporate investment arm, typically with strategic as well as financial motives.; invtype:corporate-vc
Crossover or public-market fund no records yet: A public-markets investor buying into private rounds, usually late and often ahead of a listing.; invtype:crossover
Development bank no records yet: A multilateral or national development institution lending against policy goals.; invtype:development-bank
Family office no records yet: Private capital managed for one family. Often the earliest and most patient money in this sector.; invtype:family-office
Government agency no records yet: A public body deploying public money, usually against policy objectives rather than returns.; invtype:government-agency
Sovereign wealth fund no records yet: A state investment fund.; invtype:sovereign-wealth
Strategic corporate no records yet: An operating company investing for commercial advantage — a utility, a supplier, a customer.; invtype:strategic
Venture capital no records yet: A fund investing other people’s money for financial return.; invtype:venture

Funding rounds 9

Bridge no records yet: Short-term financing between rounds. Frequently a signal about timing rather than about progress.; round:bridge
Growth no records yet: Large round raised outside the lettered sequence, often from crossover or strategic investors.; round:growth
Pre-seed no records yet: The earliest institutional money, usually before a working prototype.; round:pre-seed
Seed no records yet: First substantial round, typically funding a first demonstration.; round:seed
Series A no records yet: First priced venture round, usually after a technical result.; round:series-a
Series B no records yet: Scaling round, typically funding a larger machine.; round:series-b
Series C no records yet: Later-stage round, typically toward a pilot plant.; round:series-c
Series D no records yet: Late-stage round.; round:series-d
Series E no records yet: Very late-stage round; in this sector often the one funding first-of-a-kind construction.; round:series-e

Fuels 9

Deuterium–deuterium D-D 10 records: Deuterium only. Needs far higher temperature than D-T but the fuel is abundant in seawater and no tritium breeding is required.; fuel:d-d
Deuterium–helium-3 D-³He 2 records: Deuterium with helium-3. Most energy released as charged particles rather than neutrons, which allows direct electrical conversion — but helium-3 is vanishingly scarce on Earth.; fuel:d-he3
Deuterium–tritium D-T 40 records: Lowest ignition threshold; 80% of energy in 14.1 MeV neutrons. The reference fuel for every near-term net-gain claim.; fuel:d-t
High-assay low-enriched uranium HALEU 15 records: 5–20% U-235. The binding supply constraint for most advanced reactor designs.; fuel:haleu
Low-enriched uranium 19 records: Below 5% U-235.; fuel:leu
Mixed oxide fuel MOX 5 records: Mixed oxide fuel, combining plutonium with uranium. Uses material recovered from reprocessing rather than fresh enrichment.; fuel:mox
Proton–boron-11 p-¹¹B 5 records: Aneutronic, and requires roughly an order of magnitude more triple product than D-T. A p-¹¹B roadmap that skips D-T is a listed red flag.; fuel:p-b11
Thorium 2 records: Thorium-232, which is fertile rather than fissile: it must absorb a neutron to become uranium-233 before it can fission. More abundant than uranium.; fuel:thorium
TRISO particle fuel 6 records: Fuel kernels wrapped in layers of carbon and silicon carbide, each particle its own containment vessel. Retains fission products to very high temperature.; fuel:triso

Licences 8

CC BY no records yet: Attribution required — populate attribution or the gate fails.; license:cc-by
CC BY-SA no records yet: Creative Commons Attribution-ShareAlike: reusable with credit, but derivatives must carry the same licence — which is why it is tracked separately from CC BY.; license:cc-by-sa
Fair dealing — identification no records yet: A third party's copyrighted image shown at reduced size to identify what an organisation makes, with attribution and a link to the source. Weaker than trademark-nominative use, which covers logos: a mark may be reproduced to name its owner, whereas a product photograph is a creative work and its use rests on fair dealing or fair use. Recorded distinctly so these can be found and removed on request.; license:fair-dealing-identification
Nominative trademark use no records yet: Using a mark to identify the entity it belongs to, in an editorial directory, unmodified and without implying endorsement. The normal basis for logos here. It is a defensible position, not a licence granted to us — the mark stays the owner's.; license:trademark-nominative
Permission granted no records yet: Explicit written permission. Record who granted it and when in attribution.; license:permission-granted
Press kit no records yet: Published by the owner for media use. Check the accompanying terms, which often restrict modification.; license:press-kit
Public domain no records yet: No copyright restrictions apply. Common for work produced by US federal agencies.; license:public-domain
Unknown no records yet: Placeholder only. An asset with license:unknown must never be published; the gate rejects it. Use it to park a capture pending a licence determination, never to ship one.; license:unknown

Facility types 8

Enrichment plant no records yet: A facility that raises the fissile fraction of uranium.; ftype:enrichment-plant
Fuel fabrication plant no records yet: A facility that manufactures reactor fuel.; ftype:fuel-fabrication
Fusion device 60 records: An experimental machine that confines plasma for fusion research — tokamaks, stellarators, mirrors, pinches. Laser and pulsed-power drivers are ftype:laser-facility instead.; ftype:fusion-device
Laser facility 1 record: A driver facility that compresses fuel using laser or pulsed-power energy rather than confining it magnetically.; ftype:laser-facility
Manufacturing site no records yet: A factory producing components, modules or materials for the sector.; ftype:manufacturing
Power reactor no records yet: A reactor built to generate power commercially, rather than to conduct research.; ftype:power-reactor
Research reactor no records yet: A reactor operated for experiments, isotope production or training rather than for grid power.; ftype:research-reactor
Test stand no records yet: A rig for testing components or subsystems outside a complete machine.; ftype:test-stand

Assertion types 7

Diagram or schematic no records yet: A technical drawing or schematic.; atype:diagram
Facility photograph no records yet: A photograph of a plant, device or site.; atype:facility-photo
Headshot no records yet: A photograph of a person.; atype:headshot
Icon no records yet: Square mark without the wordmark, for favicons and dense table rows.; atype:icon
Logo no records yet: The organization's primary identifying mark.; atype:logo
Product image no records yet: A picture of what an organisation makes. A copyrighted work, unlike a logo, so it is shown for identification with attribution.; atype:product-image
Wordmark no records yet: A logo consisting of the organisation’s name set as type, rather than a symbol.; atype:wordmark

Programmes 6

ARPA-E no records yet: US advanced research agency for energy, funding high-risk work including several fusion concepts.; prog:arpa-e
DOE Milestone-Based Fusion Development Program no records yet: US Department of Energy programme paying private fusion developers on delivery of agreed technical milestones rather than up front.; prog:doe-milestone-based-fusion
EUROfusion no records yet: The European consortium coordinating fusion research across member states, and the operator of record for JET.; prog:eurofusion
ITER no records yet: The international tokamak under construction in France, funded by seven members representing over half the world’s population.; prog:iter
NRC Advanced Reactor Content of Application Project no records yet: The US Nuclear Regulatory Commission’s Advanced Reactor Content of Application Project, defining what an advanced-reactor application must contain.; prog:nrc-arcap
UK STEP no records yet: Spherical Tokamak for Energy Production: the UK programme to build a prototype fusion power plant at West Burton.; prog:uk-step

Product stages 6

Commercial no records yet: Sold and deployed to customers.; pstage:commercial
Concept no records yet: Described on paper. No hardware exists.; pstage:concept
Discontinued no records yet: No longer developed or offered. Kept in the record rather than deleted.; pstage:discontinued
In development no records yet: Actively engineered, with hardware being built or tested, but not yet a working whole.; pstage:development
Prototype no records yet: A working article exists and is being tested. Not necessarily at full scale.; pstage:prototype
Qualified no records yet: Formally demonstrated against a specification or certified by an authority.; pstage:qualified

Milestone types 5

Commercial no records yet: A market event: a contract, an offtake, a first sale.; mstype:commercial
Construction no records yet: A physical build milestone — first concrete, module delivery, vessel installation.; mstype:construction
Financial no records yet: A funding or corporate-finance event.; mstype:financial
Regulatory no records yet: A step in a licensing process, decided by a regulator rather than the developer.; mstype:regulatory
Technical no records yet: An achievement of the machine or the physics.; mstype:technical

Sectors 4

Fission 60 records: Advanced and small modular fission reactor developers, plus established reactor vendors.; sector:fission
Fuel cycle 22 records: Mining, conversion, enrichment, fabrication, reprocessing, waste and tritium supply.; sector:fuel-cycle
Fusion 60 records: Organizations pursuing energy from nuclear fusion, and their dedicated supply chain.; sector:fusion
Supply chain 50 records: Components, materials, instrumentation and services sold into fusion or fission programmes.; sector:supply-chain

Term ids are immutable. A term is never renamed or deleted — it is marked deprecated and pointed at its replacement — because an id that changes meaning silently rewrites every record that used it. See methodology, and the gain page for why six of these terms exist where other directories have one.