Uranium & Nuclear Glossary

The uranium market runs on jargon: SWU, tails assay, book transfer, EV per pound. Here is what 72 of the terms that matter actually mean, in plain English, each linked to the live data or the guide that goes deeper. Reference only, not investment advice.

Uranium & nuclear fuel

Uranium (U)#: A naturally occurring heavy metal, atomic number 92, mildly radioactive. Its fissile isotope uranium-235 splits when it absorbs a neutron and releases energy, which is what powers a nuclear reactor. Natural uranium is about 99.3% uranium-238 and only 0.7% uranium-235, so most reactors need it enriched before use.; See also: Uranium-235, Uranium-238, Enrichment
Yellowcake (U₃O₈)#: The uranium concentrate that comes out of a mill, chemically triuranium octoxide (U₃O₈), roughly 70–90% uranium. It is the form uranium is bought and sold in, so when investors quote a "uranium price" per pound, they mean yellowcake. Despite the name, modern yellowcake is usually brown or khaki, not bright yellow.; What is yellowcake? →See also: U₃O₈, Milling, Spot price
U₃O₈#: Triuranium octoxide, the chemical form of yellowcake and the standard unit for pricing uranium. Prices are quoted in US dollars per pound of U₃O₈. One pound of U₃O₈ contains about 0.848 pounds of uranium metal.; See also: Yellowcake, Pounds U₃O₈
Uranium-235 (U-235)#: The fissile isotope of uranium, present at about 0.7% in natural uranium. It sustains the chain reaction in most reactors. Enrichment raises its concentration to the 3–5% used in conventional power reactors, and higher for research reactors and some advanced designs.; See also: Uranium-238, Enrichment, Low-enriched uranium
Uranium-238 (U-238)#: The dominant isotope of natural uranium, about 99.3%. It is not readily fissile but is "fertile": it can absorb a neutron and become plutonium-239, which is fissile. Depleted uranium is mostly U-238 left over after enrichment.; See also: Uranium-235, Depleted uranium, Plutonium
UF₆ (uranium hexafluoride)#: The chemical form uranium is turned into for enrichment. Conversion plants react yellowcake into uranium hexafluoride, a compound that becomes a gas at low temperature, which is required for the centrifuge enrichment process. Priced separately from uranium, in dollars per kilogram of uranium as UF₆.; Fuel supply chain →See also: Conversion, Enrichment
Enriched uranium product (EUP)#: The finished output of enrichment: uranium with its U-235 content raised to the level a reactor needs. Its cost combines the feed uranium and the enrichment work (SWU) used to make it. Sometimes bought directly instead of buying feed and enrichment separately.; See also: Enrichment, Separative Work Unit, Low-enriched uranium
Low-enriched uranium (LEU)#: Uranium enriched to below 20% U-235. Conventional power reactors run on LEU in the 3–5% range. The overwhelming majority of the commercial fuel market is LEU.; See also: Highly enriched uranium, High-assay low-enriched uranium, Enrichment
High-assay low-enriched uranium (HALEU)#: Uranium enriched to between 5% and 20% U-235. Many advanced reactors and small modular reactors are designed to run on HALEU. Commercial supply is scarce and, until recently, sourced largely from Russia, which has made HALEU a policy and supply-chain focus.; Enrichment stocks & HALEU →See also: Low-enriched uranium, Small modular reactor, Enrichment
Highly enriched uranium (HEU)#: Uranium enriched to 20% U-235 or more, and often far higher for weapons or naval reactors. Not used in commercial power plants. Historically, ex-weapons HEU was blended down into reactor fuel under the Megatons to Megawatts program, a major secondary supply source through 2013.; See also: Low-enriched uranium, Downblending, Megatons to Megawatts
Depleted uranium (DU)#: The uranium left over after enrichment, with less U-235 than natural uranium (the "tails"). Mostly U-238. Large stockpiles exist and can be re-enriched when enrichment is cheap, making DU a latent source of supply as well as a waste-management question.; See also: Tails assay, Underfeeding / overfeeding, Uranium-238
MOX fuel#: Mixed-oxide fuel, made by blending plutonium oxide with uranium oxide. It lets recovered plutonium be reused as reactor fuel. Used in parts of Europe and Japan; not widely used in the United States.; See also: Plutonium, Reprocessing
TRISO fuel#: Tristructural-isotropic fuel: uranium kernels coated in layers of carbon and ceramic that contain the reaction products at high temperature. Marketed as very robust and meltdown-resistant, it is the fuel for several advanced and microreactor designs.; See also: High-assay low-enriched uranium, Small modular reactor
Plutonium#: A fissile element created when U-238 absorbs a neutron in a reactor. It can be recovered from spent fuel and reused in MOX fuel. It is not a traded commodity for investors: it is tightly controlled weapons-usable material handled only by states and licensed operators.; Fuel supply chain →See also: MOX fuel, Reprocessing, Uranium-238

The nuclear fuel cycle

Nuclear fuel cycle#: The full path uranium takes from the ground to the reactor and beyond: mining and milling into yellowcake, conversion to UF₆, enrichment, fabrication into fuel assemblies, use in a reactor, then storage or reprocessing of spent fuel. Each stage is a separate market with its own price and its own bottlenecks.; Fuel supply chain →See also: Milling, Conversion, Enrichment, Fabrication
Milling#: Processing mined ore into uranium concentrate. A mill crushes the rock and uses acid or alkaline chemistry to dissolve and recover the uranium, which is dried into yellowcake. In-situ recovery skips the crushing and does the chemistry underground.; See also: Yellowcake, In-situ recovery, Conventional mining
Conversion#: The fuel-cycle stage that turns yellowcake into uranium hexafluoride (UF₆) so it can be enriched. Only a handful of plants worldwide do this, so conversion capacity is a chokepoint. Conversion is priced separately, in dollars per kilogram of uranium.; Fuel supply chain →See also: UF₆, Enrichment
Enrichment#: Raising the share of U-235 in uranium from the natural 0.7% to the 3–5% a reactor needs. Modern plants spin UF₆ gas in centrifuges to separate the lighter U-235. Enrichment work is measured and sold in Separative Work Units (SWU).; Enrichment stocks explained →See also: Separative Work Unit, Tails assay, Centrifuge
Separative Work Unit (SWU)#: The unit that measures enrichment work, priced in dollars per SWU. Making a batch of reactor fuel takes a certain amount of feed uranium plus a certain number of SWU; a buyer can trade one off against the other by changing the tails assay. SWU prices roughly tripled after 2022 as Western buyers moved away from Russian supply.; Enrichment stocks explained →See also: Enrichment, Tails assay, Underfeeding / overfeeding
Tails assay#: The amount of U-235 left in the depleted uranium (tails) after enrichment. A lower tails assay extracts more U-235 from each kilogram of feed but takes more SWU. Enrichers adjust it to balance the cost of uranium against the cost of enrichment, which links the two markets.; See also: Separative Work Unit, Underfeeding / overfeeding, Depleted uranium
Underfeeding / overfeeding#: How enrichers flex the tails assay to swing supply. When uranium is expensive, they run a lower tails assay to squeeze more product from less feed (underfeeding), which frees up uranium. When enrichment is expensive, they do the reverse. This makes enrichment capacity a hidden source of, or drain on, uranium supply.; See also: Tails assay, Separative Work Unit, Secondary supply
Centrifuge#: The machine that does modern enrichment. Thousands of centrifuges spin UF₆ gas at high speed so the slightly heavier U-238 drifts outward and the lighter U-235 concentrates toward the center. Centrifuges replaced the far more energy-hungry gaseous diffusion plants.; See also: Enrichment, Separative Work Unit
Fabrication#: The final front-end stage: pressing enriched uranium into ceramic pellets, stacking them in metal rods, and bundling the rods into fuel assemblies sized for a specific reactor. Fabrication is priced per kilogram and is a smaller share of fuel cost than uranium or enrichment.; See also: Nuclear fuel cycle, Enriched uranium product
Reprocessing#: Chemically separating usable uranium and plutonium out of spent fuel so they can be recycled, usually into MOX fuel. Practiced in France, Russia, Japan and elsewhere; the United States does not commercially reprocess. It is the main alternative to a once-through, direct-disposal fuel cycle.; See also: MOX fuel, Spent fuel, Plutonium
Spent fuel#: Fuel assemblies removed from a reactor after use. Highly radioactive, they are cooled in pools then moved to dry casks for interim storage, awaiting either a permanent repository or reprocessing. The back end of the fuel cycle.; See also: Reprocessing, Nuclear fuel cycle
Secondary supply#: Uranium that reaches the market from somewhere other than fresh mining: commercial and government inventories, enricher underfeeding, downblended weapons material, and reprocessed fuel. Secondary supply has repeatedly filled the gap between mine output and reactor demand, which is why mine production alone understates supply.; Supply & demand →See also: Underfeeding / overfeeding, Downblending, Inventory

Mining & resources

In-situ recovery (ISR / ISL)#: A mining method that dissolves uranium underground instead of digging it up. Operators pump a solution through the ore body via wells, then bring the uranium-loaded liquid to the surface for processing. Lower cost and lower surface impact where the geology allows it, ISR now accounts for the majority of world production, including nearly all of Kazakhstan and the US restart.; Uranium projects & methods →See also: Conventional mining, Milling, AISC
Conventional mining#: Open-pit or underground extraction of uranium ore, which is then trucked to a mill for crushing and chemical processing. Higher cost and impact than in-situ recovery but the only option for hard-rock deposits like the high-grade ores of Canada’s Athabasca Basin.; Uranium projects →See also: In-situ recovery, Milling, Ore grade
Ore grade#: How much uranium a rock contains, given as a percentage of U₃O₈ or in parts per million. World deposits average well under 1%; the Athabasca Basin in Canada hosts grades over 15%, more than a hundred times higher, which transforms a project’s economics.; Uranium projects →See also: Cutoff grade, Resources, Conventional mining
Cutoff grade#: The minimum ore grade worth mining at a given uranium price. Rock below the cutoff costs more to process than the uranium in it is worth. When the uranium price rises, the cutoff falls and more of a deposit becomes economic, which is how price feeds through to reported reserves.; See also: Ore grade, Reserves, AISC
Resources (measured, indicated, inferred)#: Estimated uranium in the ground, graded by confidence. Measured and indicated resources rest on denser drilling; inferred resources are lower-confidence extrapolations. Resources are not yet proven economic, which distinguishes them from reserves. Reporting follows codes such as NI 43-101 (Canada) and JORC (Australia).; Compare miner resources →See also: Reserves, NI 43-101 / JORC, Ore grade
Reserves#: The portion of a resource that a feasibility study has shown can be mined at a profit under current assumptions. Reserves sit at the top of the confidence ladder. Because they depend on price, a higher uranium price can convert resources into reserves without any new drilling.; See also: Resources, Cutoff grade
NI 43-101 / JORC#: The reporting standards that govern how mining companies disclose resources and reserves. NI 43-101 is the Canadian rule; JORC is the Australian equivalent. Both require a qualified person to sign off and exist to stop companies from publishing unsupported numbers. When comparing miners, check that figures are compliant.; See also: Resources, Reserves
AISC (all-in sustaining cost)#: A per-pound estimate of what it costs a miner to produce uranium and keep the operation running, including sustaining capital. Compared against the uranium price, AISC shows how much margin a producer earns per pound. A rough screen for which projects are profitable at today’s price.; Miner screener (AISC) →See also: Ore grade, EV per pound
Pounds U₃O₈#: The standard quantity unit for uranium in North American markets: a pound of U₃O₈. Resources, production and contracts are usually sized in millions of pounds (Mlb). Elsewhere the industry uses kilograms or tonnes of uranium metal (kgU, tU); one tonne of uranium equals about 2,600 pounds of U₃O₈.; See also: U₃O₈, Yellowcake

Prices & the market

Spot price#: The price for uranium delivered soon, conventionally within about a year. Uranium does not trade on a live exchange, so specialist reporters publish an assessed spot price based on bids, offers and transactions. Spot is a thin market: most uranium changes hands under long-term contracts, so the spot number can move more than volumes justify.; How the spot price is set →See also: Term price / long-term price, Price reporter, Sprott Physical Uranium Trust
Term price / long-term price#: The reference price for uranium delivered under multi-year contracts, which is how utilities actually buy most of their fuel. The long-term price usually trades at a premium to spot and moves more slowly. Contracting activity in the term market is a better gauge of real demand than the spot number.; Contract database →See also: Spot price, Base-escalated pricing, Contracting cycle
Price reporter#: A specialist firm that assesses and publishes uranium prices because there is no exchange doing it. UxC and TradeTech are the two main ones; their weekly numbers settle contracts and futures. Their assessments reflect the most competitive offer they are aware of, not necessarily a completed trade, and the current values sit behind subscriptions.; How the spot price is set →See also: Spot price, Term price / long-term price
UxC / TradeTech#: The two dominant uranium price-reporting firms. UxC publishes the Ux U₃O₈ Price; TradeTech publishes the NUEXCO Exchange Value and a daily spot indicator. Their prices are the entrenched settlement references for contracts and CME futures. The headline numbers are paywalled, which is why a free, transparent price layer is valuable.; See also: Price reporter, Spot price
Incentive price#: The uranium price high enough, and sustained long enough, to justify building new mines. Much of the world’s undeveloped supply needs a price well above the historical spot average to break ground. The gap between today’s price and the incentive price is central to the bull case for a supply deficit.; Uranium investment thesis →See also: AISC, Term price / long-term price
Carry trade#: Buying physical uranium on the spot market and holding it to sell later, betting the price will rise faster than storage costs. Financial vehicles like Sprott’s trust industrialized the idea, taking pounds off the market and tightening spot supply in the process.; See also: Sprott Physical Uranium Trust, Spot price

Contracts & trading

Long-term contract#: A multi-year agreement under which a utility buys uranium from a producer, often covering deliveries several years out. This is the backbone of the market: utilities contract ahead to guarantee fuel. A wave of contracting signals utilities rebuilding coverage, which supports prices.; Contract database →See also: Term price / long-term price, Contracting cycle, Coverage
Base-escalated pricing#: A contract structure that fixes a base uranium price and then escalates it over time by an index such as inflation. It gives the producer predictable revenue and the utility predictable cost, insulated from spot swings. The main alternative to market-related pricing.; See also: Market-related pricing, Floor & ceiling
Market-related pricing#: A contract that ties the delivery price to the published spot or long-term price near the time of delivery, often bounded by a floor and a ceiling. It keeps the utility close to the market rate while protecting both sides from extremes.; See also: Base-escalated pricing, Floor & ceiling, Term price / long-term price
Floor & ceiling#: The minimum and maximum prices written into a market-related contract. The floor protects the producer if the market falls; the ceiling protects the utility if it spikes. Where the floors and ceilings of recent contracts sit tells you the price range the industry is actually transacting around.; See also: Market-related pricing, Base-escalated pricing
Book transfer#: How uranium usually "delivers": ownership of material already sitting at a licensed converter such as Cameco, ConverDyn or Orano changes on the facility’s books, with no physical shipment. It is why buyers rarely move uranium and why a trust’s pounds can sit in storage while title trades.; Physical uranium holdings →See also: Conversion, Sprott Physical Uranium Trust
Contracting cycle#: The ebb and flow of utility buying. Utilities contract heavily when they fear supply is tightening and go quiet when they feel covered. Because reactors must be fueled regardless, deferred buying builds up into a wave of demand later. Tracking contracting volume is a way to read the market ahead of price.; Contract database →See also: Coverage, Long-term contract
Coverage#: How much of a utility’s future fuel need is already locked in under contract. Near-term coverage is typically high; it thins out years into the future, and those uncovered pounds are the demand producers are chasing. Coverage gaps a few years out are a leading indicator of contracting to come.; Utility coverage gap →See also: Contracting cycle, Long-term contract
CME uranium futures (UX)#: Exchange-traded futures on the uranium price, listed on the CME. Each contract covers 250 pounds of U₃O₈ and settles financially against the published weekly price, so no uranium is delivered. Open interest is thin compared with major commodities, but futures give traders and utilities a hedging and price-discovery tool.; Uranium futures →See also: Spot price, Price reporter

Investment vehicles

Sprott Physical Uranium Trust (SPUT)#: A closed-end trust that holds physical uranium and trades on the Toronto exchange, letting investors get price exposure without owning stocks. When SPUT issues units and buys pounds, it removes uranium from the spot market. Its market price can trade above or below the value of its holdings.; SPUT deep dive →See also: Premium / discount to NAV, Net asset value, Physical uranium trust
Yellow Cake plc (YCA)#: A London-listed company that holds physical uranium, similar in spirit to Sprott’s trust. It offers investors a pounds-in-the-ground proxy with a long-term supply agreement with Kazatomprom. Like SPUT, its shares can trade at a premium or discount to the value of the uranium it holds.; Physical uranium holdings →See also: Sprott Physical Uranium Trust, Physical uranium trust, Premium / discount to NAV
Physical uranium trust#: Any vehicle whose main asset is stored uranium rather than mining shares. It tracks the uranium price more directly than a miner, with no operational or cost risk, but also no production growth or dividends. SPUT and Yellow Cake plc are the largest.; Physical uranium holdings →See also: Sprott Physical Uranium Trust, Yellow Cake plc, Net asset value
Net asset value (NAV)#: The per-share value of what a fund or trust owns. For a physical uranium trust, NAV is essentially the pounds it holds times the uranium price, divided by shares. Comparing market price to NAV shows whether the vehicle trades at a premium or a discount.; SPUT premium/discount →See also: Premium / discount to NAV, Sprott Physical Uranium Trust
Premium / discount to NAV#: The gap between a trust’s market price and its net asset value. A premium means investors pay more than the underlying uranium is worth, which can let the trust issue units and buy more pounds; a discount means the opposite and can stall buying. A watched signal for physical uranium demand.; SPUT premium/discount history →See also: Net asset value, Sprott Physical Uranium Trust
Uranium ETF#: A fund that holds a basket of uranium-related stocks so investors get diversified exposure in one ticker. The largest are Global X’s URA and Sprott’s URNM and URNJ. Most hold miners and fuel-cycle companies, not physical uranium, so they carry equity risk rather than pure price exposure.; Uranium ETFs compared →See also: URA, URNM / URNJ, Physical uranium trust
URA (Global X Uranium ETF)#: The largest and most-traded uranium ETF, holding miners plus some physical-uranium and fuel-cycle exposure. Broader and more liquid than the pure-miner funds, which makes it a common first stop for uranium exposure, but its breadth dilutes leverage to the uranium price.; URA complete guide →See also: Uranium ETF, URNM / URNJ
URNM / URNJ#: Sprott’s uranium ETFs. URNM concentrates on uranium miners and physical holdings; URNJ focuses on smaller junior miners and explorers, offering higher risk and higher potential leverage to the uranium price. Both are more uranium-pure than URA.; URA vs URNM vs URNJ →See also: URA, Uranium ETF
Royalty & streaming#: A financing model where a company pays a miner upfront in exchange for a cut of future production or revenue. It gives investors uranium exposure without operating a mine, spreading risk across projects. Uranium Royalty Corp is the main listed pure-play.; Uranium royalty stocks →See also: EV per pound
EV per pound (EV/lb)#: A valuation yardstick for uranium miners: enterprise value divided by pounds of uranium resource. It lets you compare companies of different sizes on how much the market pays per pound in the ground. Low EV/lb can flag value, but it ignores grade, cost, jurisdiction and timeline, so use it alongside AISC.; Miner screener →See also: AISC, Resources

Reactors & demand

Light-water reactor (LWR)#: The dominant commercial reactor type, using ordinary water as both coolant and moderator. The two main variants are pressurized-water reactors (PWR) and boiling-water reactors (BWR). LWRs run on low-enriched uranium and account for most of the world’s uranium demand.; See also: Reactor requirements, Low-enriched uranium
Small modular reactor (SMR)#: A reactor with output up to about 300 MW, built from factory-made modules rather than constructed on-site. The pitch is faster, cheaper, scalable deployment, including for data centers. Many designs need HALEU fuel. Most SMR companies are pre-revenue, so timelines and order books matter more than hype.; SMR & reactor tracker →See also: High-assay low-enriched uranium, Microreactor, Reactor requirements
Microreactor#: A very small reactor, typically under about 20 MW, designed to be transportable and to power remote sites, military bases or single facilities. Often uses TRISO or HALEU fuel. An emerging niche within the advanced-reactor field, still largely pre-commercial.; Reactor tracker →See also: Small modular reactor, TRISO fuel
Reactor requirements#: The uranium the world’s reactor fleet needs to run, the core of demand forecasting. It is estimated from the number of reactors, their size, how hard they run and their refueling schedules. Requirements grow with new builds and restarts and are the demand side of the supply-deficit thesis.; Supply & demand →See also: Capacity factor / load factor, Secondary supply
Capacity factor / load factor#: The share of its maximum output a reactor actually produces over a year. Nuclear plants run at very high capacity factors, often above 90%, because they are built to provide steady baseload power. Higher utilization means more uranium burned, so it feeds directly into demand estimates.; See also: Reactor requirements, Baseload power
Baseload power#: The constant, always-on electricity a grid needs around the clock. Nuclear is a classic baseload source because it runs steadily regardless of weather, unlike wind or solar. The case for nuclear powering data centers rests on this reliability.; See also: Capacity factor / load factor, Reactor requirements
Life extension / uprate#: Keeping existing reactors running longer (life extension) or squeezing more output from them (uprate). Both add uranium demand without any new construction and have become a major growth source as countries relicense aging fleets and even restart shuttered plants.; See also: Reactor requirements

Policy & trade

Russian uranium import ban#: A 2024 US law barring imports of Russian low-enriched uranium, with waivers available through 2027 and a hard stop after 2028. Because Russia supplied a large share of Western enrichment, the ban reshaped the enrichment and conversion markets and accelerated the push for domestic HALEU and SWU capacity.; Policy & waiver ledger →See also: High-assay low-enriched uranium, Waiver, Enrichment
Waiver#: A temporary government permission to keep importing Russian enriched uranium despite the ban, granted to utilities that can show no alternative supply. Waivers phase out toward 2028. Which utilities hold them, and for how long, marks who is most exposed to the enrichment squeeze.; Policy & waiver ledger →See also: Russian uranium import ban, Enrichment
Megatons to Megawatts#: A 1993–2013 program under which Russian weapons-grade HEU was blended down into reactor fuel and sold to the United States. For two decades it supplied a large slice of US reactor fuel from secondary sources, suppressing the uranium price and discouraging new mine investment. Its 2013 end removed a major supply cushion.; See also: Downblending, Highly enriched uranium, Secondary supply
Downblending#: Mixing highly enriched uranium with lower-assay material to bring it down to reactor-grade LEU. It turns weapons stockpiles into commercial fuel and is a source of secondary supply. Megatons to Megawatts was the largest downblending program in history.; See also: Megatons to Megawatts, Highly enriched uranium, Low-enriched uranium
Section 232 / trade remedies#: US trade-law tools that can restrict uranium imports on national-security grounds. A 2018–2019 Section 232 investigation into uranium imports stopped short of quotas but put domestic-supply security on the policy agenda, feeding into later measures like the Russian import ban and federal purchases.; Policy & waiver ledger →See also: Russian uranium import ban
Inventory#: Stockpiled uranium held by utilities, producers, governments and traders. Inventories act as a buffer: when they are ample, buyers can wait and prices stay soft; when they are drawn down, buyers must return to the market. Estimating who holds how much is central to reading the supply-demand balance.; Supply & demand →See also: Secondary supply, Coverage

Want the numbers behind the terms? Start with the live spot price, the miner screener, or the investing guides.