# Nuclear fuel cycle The **nuclear fuel cycle** is the industrial chain that carries [[Uranium|uranium]] from ore to a reactor core and the [[Spent_nuclear_fuel|spent fuel]] out again — a *front end* of mining, conversion, [[Enriched_uranium|enrichment]] and fabrication, a *service period* inside the [[Nuclear_reactor|reactor]], and a *back end* of storage, optional recycling and final disposal. It is called a cycle because some versions close the loop by recovering [[Plutonium|plutonium]] and unburned uranium, and most versions in practice do not. In the microsim below the reader follows one tonne of natural uranium — 7.2 kg of ²³⁵U in 992.8 kg of ²³⁸U — and sets three controls: the enrichment target, the tails assay, and the burnup.[^murphy-fc][^spec-e50] The enrichment panel is a cascade: [[Graham's_law|Graham's law]], `r₁/r₂ = √(M₂/M₁)`, gives UF₆ a per-stage separation factor of √(352.04/349.03) = 1.0043, a 0.43 % edge, so about 400 stages are needed to reach 4 % and more than a thousand to approach purity.[^averill-fc][^derived-fc] Beside it runs the mass balance, `F/P = (x_p − x_t)/(x_f − x_t)`, and the separative work `SWU = P·V(x_p) + T·V(x_t) − F·V(x_f)` with `V(x) = (1 − 2x)·ln((1 − x)/x)`, a standard form no Portal Book prints.[^spec-e50][^derived-fc] A second panel runs the in-core chain on a logarithmic time axis, ²³⁸U(n,γ) → ²³⁹U (23.5 min) → ²³⁹[[Neptunium|Np]] (2.4 d) → ²³⁹Pu (24,100 yr), evaluated from the closed-form Bateman solution because its half-lives span nine decades and no fixed-step integrator can cross them.[^murphy-fc][^spec-e50] A third shows the back end: the ⁹⁰Sr and ¹³⁷Cs window that dominates the waste from about five years to three hundred.[^murphy-fc] On the [[Energy]] flagship this article serves *The fuel cycle* section of Part V — Transformation, and it places uranium, plutonium and [[Thorium|thorium]] on the spine. It takes its fission physics from [[Nuclear_chain_reaction]] and its core behaviour from [[Nuclear_reactor]]. ## Basic concepts Two facts organise everything. First, natural uranium is 0.72 % ²³⁵U and 99.2745 % ²³⁸U, a ratio of about 140 to 1, and only the ²³⁵U is [[Fissile_material|fissile]] — so the front end exists to change that ratio.[^murphy-fc] Second, the ²³⁸U is not inert: it captures neutrons and becomes ²³⁹Pu, which is fissile, so the reactor manufactures part of its own fuel while consuming the rest, and the back end exists to decide what to do about it. The cycle's accounting unit is the tonne of heavy metal and its energy unit the megawatt-day. Taking the sim's tonne of natural uranium to a 4 % product at a 0.3 % tails assay needs 8.81 tonnes of feed per tonne of product, so one tonne yields 113.5 kg of fuel and 886.5 kg of depleted uranium, with the ²³⁵U ledger closing at 4.54 kg in the product and 2.66 kg in the tails.[^derived-fc] At Murphy's other-end scale of 4.5 g of ²³⁵U per person-year, that 113.5 kg would serve a thousand people for a year if every fissile atom burned.[^murphy-fc][^derived-fc] ## Front end The front end is chemistry and physics applied to a ratio of 1 in 140. Each of its six steps concentrates the material — ore to concentrate, concentrate to gas, gas to enriched gas, gas to ceramic — and only one of them, enrichment, touches the isotopic ratio at all. ### Exploration Uranium is a common crustal element, so exploration looks not for its presence but for concentrations worth mining: sandstone-hosted roll fronts, unconformity deposits and a few other settings in which groundwater has dissolved uranium from a large volume of rock and redeposited it in a small one. Airborne and ground radiometric surveys find the gamma signature of the [[Decay_chain|decay chain]] rather than the uranium itself, and drilling confirms grade and tonnage.[^kerlin-fc][^wna-fc] ### Mining Ore is won by open pit, by underground workings or — increasingly — by in-situ recovery, in which a leaching solution is pumped through the ore body and the loaded solution brought to surface, leaving the rock in place. In-situ recovery avoids tailings entirely but is confined to permeable, water-saturated deposits; conventional mining produces large volumes of low-activity tailings whose long-term management is the industry's characteristic surface liability.[^wna-fc] ### Milling Milling crushes and leaches the ore, usually with sulfuric acid, and precipitates a uranium concentrate — yellowcake, mostly U₃O₈ — at around 80 % uranium. Because uranium's daughters remain with the tailings while the uranium leaves, the residues carry most of the ore's [[Radioactive_decay|radioactivity]] in a finely divided form, and covering them against radon release and water contact is the plant's permanent obligation.[^wna-fc][^kerlin-fc] ### Uranium conversion Enrichment needs a gas, and uranium has only one convenient one. The concentrate is purified and converted to uranium hexafluoride, UF₆, which sublimes near 56 °C at atmospheric pressure. [[Fluorine|Fluorine]] has a single stable [[Isotope|isotope]], so all of the mass difference between ²³⁵UF₆ and ²³⁸UF₆ is the uranium's — 349.03 against 352.04 g/mol — and none of it is blurred by the fluorine.[^averill-fc] That choice of molecule is the reason enrichment works at all. ### Enrichment Because the two isotopes are chemically identical, separation exploits mass alone, and the effect is tiny. Graham's law gives the effusion rate ratio `r₁/r₂ = √(M₂/M₁)` = √(352.04/349.03) = 1.0043 for the two hexafluorides, so one ideal stage lifts the ²³⁵U fraction from 0.720 % to 0.723 %.[^averill-fc] Reaching 4 % takes about 400 such stages and 99 % about 1,150 on the textbook's simplified model, which multiplies the *fraction*; applied properly to the isotope *ratio* x/(1 − x), the count roughly doubles.[^averill-fc][^derived-fc] A [[Gaseous_diffusion|gaseous diffusion]] plant is that cascade in hardware, which is why it consumed so much electricity; centrifuges have a far larger per-stage factor.[^wna-fc] The economics live in two equations. The mass balance `F/P = (x_p − x_t)/(x_f − x_t)` gives the uranium a kilogram of product costs; the separative work `SWU = P·V(x_p) + T·V(x_t) − F·V(x_f)`, with `V(x) = (1 − 2x)·ln((1 − x)/x)`, gives the enrichment effort. For 4 % product at 0.3 % tails from 0.72 % feed, one tonne gives 113.5 kg of fuel for 592 SWU, or 5.2 SWU per kilogram. Drop the tails to 0.2 % and the same tonne yields 136.8 kg — 21 % more fuel — but the work rises to 885 SWU, up 49 %. The tails assay trades uranium price against enrichment cost, and enrichers turn it whenever the two move apart.[^derived-fc] The same equations explain why enrichment is safeguarded. Reactor fuel is 3–5 % ²³⁵U; weapons-usable material begins at 20 % and is typically about 85 %.[^murphy-fc][^ball-fc] Taking the same tonne to 90 % yields only 4.7 kg — but for 896 SWU, almost exactly the work that made 137 kg of reactor fuel. Most of the effort goes into the climb from 0.72 % to 4 %: hence the safeguards focus on enrichment capacity rather than level.[^derived-fc][^iaea-fc] ### Fabrication Enriched UF₆ is converted to uranium dioxide powder, pressed and sintered into [[Ceramic|ceramic]] pellets, and stacked in sealed [[Zirconium|zirconium]]-alloy tubes that are assembled into bundles with spacers and end fittings. The ceramic is chosen because it retains fission gases and does not melt until about 2,800 °C; the alloy because it is nearly transparent to neutrons and resists [[Corrosion|corrosion]] in hot water. Every dimension in the bundle is a reactor-physics quantity, since the moderator-to-fuel ratio is set by the lattice pitch.[^wna-fc][^kerlin-fc] ## Service period Inside the core the fuel is simultaneously consumed, transmuted and poisoned, and the cycle's central asymmetry appears: what comes out is far more complicated than what went in. Everything downstream — storage, transport, recycling, disposal — follows from that one fact. ### Transport of radioactive materials Fresh fuel is only mildly radioactive and travels as ordinary freight under modest packaging rules. The regulated cases are UF₆ cylinders, hazardous chemically more than radiologically, and irradiated fuel, which needs massive shielded casks.[^wna-fc] ### In-core fuel management The engineer's job is to place each assembly where it is worth most: a fresh one carries excess reactivity that absorbers must suppress, while a partly burned one is worth more in a high-flux position. Meanwhile ²³⁸U captures neutrons and starts the chain the sim traces — ²³⁸U(n,γ) → ²³⁹U, which [[Beta_decay|beta-decays]] in 23.5 minutes to ²³⁹Np, which decays in 2.4 days to ²³⁹Pu, whose 24,100-year half-life makes it permanent on the timescale of a fuel cycle.[^murphy-fc] Because those half-lives span nine decades, the trace is drawn from the analytic Bateman solution on a logarithmic axis, never stepped.[^spec-e50] The bred plutonium is not a by-product but a fuel. At a discharge burnup of 45 GW-days per tonne, the sim's 113.5 kg of 4 % fuel yields about 5,110 thermal megawatt-days; the 4.54 kg of ²³⁵U loaded into it accounts for only some 3,200 of those once the roughly one in six ²³⁵U nuclei lost to capture rather than fission is counted, so more than a third of the energy comes from plutonium made in place.[^derived-fc][^lamarsh-fc] A light-water reactor is, quietly, a partial breeder. ### On-load reactors Heavy-water designs refuel one channel at a time while running, which lets them use natural uranium — no front-end enrichment at all — and keeps the core's excess reactivity near zero throughout life. The price is a continuous fuel-handling operation and a much larger throughput of fuel per unit of energy.[^wna-fc] ### Interim storage Discharged fuel goes first into a water pool at the reactor, where the water cools it and shields the site. After several years the [[Decay_heat|decay heat]] has fallen far enough for air cooling, and assemblies are moved to dry casks of steel and concrete standing on a pad. Interim storage is engineered for decades and, in the absence of a repository, has become the de facto back end nearly everywhere.[^wna-fc] ### Transportation Moving spent fuel between reactor, storage site and reprocessing plant or repository uses the same shielded casks, and is the cycle's most publicly visible step. The packaging rules are international and performance-based: a cask must survive a prescribed drop, puncture, fire and immersion sequence intact.[^wna-fc] ### Reprocessing [[Nuclear_reprocessing|Reprocessing]] dissolves the fuel in nitric acid and separates the uranium and plutonium from the fission products by solvent extraction, so both can be refabricated — the plutonium as mixed-oxide fuel. It recovers most of the energy value left in the assembly and reduces the volume of high-level waste, but it separates plutonium into a directly usable form, which is the reason several states with the technical capability have chosen not to use it.[^wna-fc][^kerlin-fc] ### Partitioning and transmutation A further step would separate the minor [[Actinide|actinides]] — [[Neptunium|neptunium]], [[Americium|americium]], [[Curium|curium]] — and destroy them by fission in a fast reactor or an accelerator-driven system. Because these nuclides dominate the waste's radiotoxicity after the first few hundred years, removing them would in principle shorten the disposal problem from hundreds of thousands of years to a few hundred. No such system operates industrially, and the separation efficiencies required are severe.[^wna-fc] ### Waste disposal High-level waste is the fission products plus whatever actinides were not recovered, and its hazard has two eras. For the first three centuries ⁹⁰Sr and ¹³⁷Cs dominate; both half-lives are close to 30 years, so ten of them — about 300 years — cut the activity a thousandfold.[^murphy-fc][^derived-fc] Beyond that the long-lived actinides govern. The consensus solution is vitrification in borosilicate [[Glass|glass]] inside metal canisters, emplaced in a deep geological repository in stable rock, with the design case running to hundreds of thousands of years; the technical arguments are settled far more firmly than the siting ones, which are political and generational rather than engineering questions.[^iaea-fc][^theis-fc][^kerlin-fc] The engineering case rests on independent barriers — glass, canister, backfill, host rock — and on rock in which groundwater moves slower than the waste decays. The quantity is small: at 45 GW-days per tonne a 1 GW-electric station retires only about 22 tonnes of fuel a year, so national inventories run to thousands of tonnes, not millions.[^derived-fc] The problem is confidence over deep time, not volume.[^iaea-fc] ## Fuel cycles The named cycles differ in one decision: what is done with the plutonium and the uranium still in the spent fuel. The choice is never purely technical, because separating plutonium creates a material that safeguards must then account for, and the resource argument and the proliferation argument point in opposite directions. ### Once-through nuclear fuel cycle In the once-through or open cycle the fuel is used once and the assembly becomes waste. It is the simplest option, the cheapest at current uranium prices, and the most proliferation-resistant, because no plutonium is ever separated. Its cost is resource efficiency: it extracts a few percent of the energy in the mined uranium and discards the rest, including the 886.5 kg of depleted uranium the sim's tonne leaves behind at the enrichment plant.[^derived-fc][^wna-fc] ### Plutonium cycle Recycling the recovered plutonium as mixed-oxide fuel in ordinary reactors closes part of the loop and displaces some enrichment, but plutonium can be recycled only once or twice in a thermal spectrum, because each pass degrades its isotopic quality. Closing the loop properly requires a fast spectrum.[^wna-fc] ### Minor actinides recycling Recycling the minor actinides along with the plutonium completes partitioning and transmutation, and shares that programme's obstacles: the separations are difficult, the fuels intensely radioactive to fabricate, and the reactors that would burn them unbuilt. It is research, not industry.[^wna-fc] ### Uranium cycle in renewable mode A [[Breeder_reactor|fast breeder]] fuelled by plutonium and blanketed in ²³⁸U can make more fissile material than it consumes, which would turn the world's depleted uranium stockpiles — the 99.3 % of mined uranium the open cycle discards — into fuel, multiplying the resource by something of the order of fifty. Murphy's 27,300 t of recoverable ²³⁵U, worth about 2×10²¹ J once, becomes a far larger number in this mode.[^murphy-fc][^wna-fc] The programme has run for sixty years without reaching commercial scale. ### Thorium cycle [[Thorium_fuel_cycle|Thorium]] is about three times as abundant as uranium and is entirely fertile: ²³²Th, with a half-life of 14.0 Gyr, captures a neutron and decays through protactinium to ²³³U, which is fissile.[^murphy-fc] A thorium cycle therefore needs a fissile starter and, once running, breeds its own. Its attraction is twofold. Thorium's 14 Gyr half-life means essentially all of it is still present, so there is no 1-in-140 ratio to overcome and no enrichment step at all; and because the chain starts well below ²³⁸U in mass, it yields far fewer long-lived transuranic [[Actinide|actinides]], which shortens the disposal argument.[^murphy-fc] The difficulties are equally structural. The intermediate ²³³Pa absorbs neutrons over its 27-day half-life, so a good thorium breeder must hold it out of the flux while it decays; the ²³³U arrives with a ²³²U contaminant whose chain emits hard gamma rays, making fabrication remote-handled; and no thorium infrastructure exists at any scale. The [[Liquid_fluoride_thorium_reactor|molten-salt route]], in which the fuel dissolves in the coolant and the protactinium can be drawn off continuously, addresses the first directly.[^wna-fc] ### Current industrial activity Industrially, the world runs an almost-open cycle. Mining, conversion, enrichment and fabrication operate at scale in a handful of countries; reprocessing in fewer; mixed-oxide fuel is a real but minor product; no fast breeder sells power commercially; no thorium cycle operates; and no deep repository for commercial high-level waste has yet accepted fuel.[^wna-fc] The practical fuel cycle of 2020s [[Nuclear_power|nuclear power]] is therefore front end, reactor, pool, dry cask — and a deferred decision. ## See also - [[Enriched_uranium]] - [[Isotope_separation]] — the cascade in general - [[Spent_nuclear_fuel]] - [[Nuclear_reprocessing]] - [[Breeder_reactor]] - [[Thorium_fuel_cycle]] - [[Liquid_fluoride_thorium_reactor]] - [[Nuclear_fuel]] - [[Nuclear_reactor]] — the service period in detail - [[Nuclear_chain_reaction]] — why the enrichment has to happen at all ## Notes The enrichment stage count on this page follows the Portal Book's simplified model, which multiplies the ²³⁵U *fraction* by 1.0043 per stage. That approximation is only valid while the fraction is small: extended far enough it drives the fraction past 1, which is why the properly posed calculation applies the factor to the isotope *ratio* x/(1 − x) and needs roughly twice as many stages to reach high assay. Both counts are given in the text, labelled. The separative work function `V(x) = (1 − 2x)·ln((1 − x)/x)` and the feed–product–tails balance are standard forms; no Portal Book on the Energy shelf prints either, and the SWU figures quoted here are computed from them rather than taken from a table. A real cascade never achieves the ideal, so the values are floors. The Bateman trace is exact, not integrated. Its three half-lives — 23.5 min, 2.4 d and 24,100 yr — span about nine decades, and any fixed-step scheme would either miss the first transition or take an impractical number of steps to reach the last. Footnote definitions for the whole page are collected under *References*, below. ## References [^murphy-fc]: Murphy, Thomas (2021). *Energy and Human Ambitions on a Finite Planet*. Chapter 15: Example 15.4.2, 4.5 g of ²³⁵U per person-year at 10,000 W, p. 274; natural uranium at 0.72 % ²³⁵U and 99.2745 % ²³⁸U, about 140:1, p. 277; reactor fuel at 3–5 %, weapons-usable material at ≥20 % and typically ~85 %, depleted uranium at ≤0.3 %, and the breeder chain ²³⁸U → ²³⁹U (23.5 min) → ²³⁹Np (2.4 d) → ²³⁹Pu (24,100 yr) with ²³²Th at 14.0 Gyr, pp. 277–279; the reserve figure of 27,300 t of ²³⁵U from 7.6 Mt of uranium, about 2×10²¹ J, p. 278; the ⁹⁰Sr and ¹³⁷Cs waste window from about five years to a few hundred, p. 281. https://open.umn.edu/opentextbooks/textbooks/energy-and-human-ambitions-on-a-finite-planet [^averill-fc]: Averill, Bruce; Eldredge, Patricia (2011). *General Chemistry: Principles, Patterns, and Applications*. Chapter 10, *Gases*: Graham's law `r₁/r₂ = √(M₂/M₁)`, p. 945; the UF₆ cascade with M(²³⁵UF₆) = 349.03 and M(²³⁸UF₆) = 352.04 g/mol, the per-stage factor 1.0043, one stage carrying 0.720 % to 0.723 %, and the book's stage count of about 1.15×10³ to reach 99 %, pp. 948–949. The extract carries a typo, 234.04 for 235.04, noted in sub-manual 05 §2.5. https://open.umn.edu/opentextbooks/textbooks/general-chemistry-principles-patterns-and-applications [^kerlin-fc]: Kerlin, Thomas (2013). *Future Energy: Opportunities & Challenges*. Chapter 8, pp. 267–353 (page to pin): the nuclear fuel cycle, fuel fabrication, reprocessing and waste management. https://open.umn.edu/opentextbooks/textbooks/future-energy-opportunities-challenges [^lamarsh-fc]: Lamarsh, John R.; Baratta, Anthony J. *Introduction to Nuclear Engineering*, 3rd ed. Chapters on nuclear reactor theory and fuel depletion (page to pin): the thermal capture-to-fission ratio of ²³⁵U, of order 0.17, and the conversion of ²³⁸U to ²³⁹Pu during irradiation. No Energy Portal Book states either; they are standard-text results and are cited as such. [^ball-fc]: Ball, David (2011). *Introductory Chemistry*, pp. 752–757: the chain reaction and the fissile-material thresholds, with the reactor and weapons enrichment bands drawn on the same axis, p. 757. https://open.umn.edu/opentextbooks/textbooks/introductory-chemistry [^theis-fc]: Theis, Tom; Tomkin, Jonathan, eds. (2015). *Sustainability: A Comprehensive Foundation*. Chapter 10, *Sustainable Energy Systems* (page to pin): the treatment of long-lived waste as a siting and intergenerational-equity problem rather than a purely technical one. https://open.umn.edu/opentextbooks/textbooks/sustainability-a-comprehensive-foundation [^iaea-fc]: International Atomic Energy Agency safeguards and waste-management guidance (page to pin): the safeguards significance of enrichment capacity, the definitions of low- and high-enriched uranium, and the multi-barrier case for deep geological disposal. No Energy Portal Book covers safeguards. [^wna-fc]: World Nuclear Association fuel-cycle briefings and United States Nuclear Regulatory Commission technical reference material (page to pin): exploration and deposit types, conventional and in-situ mining, milling and tailings management, conversion to UF₆, centrifuge against diffusion enrichment, fuel fabrication, transport packaging performance requirements, pool and dry-cask storage, reprocessing and mixed-oxide fuel, partitioning and transmutation, vitrification and geological disposal, on-load refuelling, and the present industrial status of breeder and thorium cycles. No Energy Portal Book carries these at the level of detail used here. [^spec-e50]: Matter & Energy Cluster contract, `_registry/plans/ENERGY_SECTIONS.md` row E50: the sim concept — one tonne of natural uranium followed through the cycle, with enrichment target, tails assay and burnup as the reader's controls; the cascade at 1.0043 per stage with feed and SWU per kilogram of product as standard forms; the in-core Bateman trace on a logarithmic time axis, never stepped; and the ⁹⁰Sr/¹³⁷Cs window at the back end. The row also records that this page's sim becomes a variant if `Nuclear_fuel.html` ships first. [^derived-fc]: Computed for this article from the equations on the page and the cited constants. Mass balance `F/P = (x_p − x_t)/(x_f − x_t)` at x_f = 0.0072: at x_p = 0.04 and x_t = 0.003, F/P = 8.81, so one tonne gives 113.5 kg of product and 886.5 kg of tails, with 4.54 kg of ²³⁵U in the product and 2.66 kg in the tails, summing to the 7.2 kg fed. Separative work with `V(x) = (1 − 2x)·ln((1 − x)/x)`: V(0.04) = 2.924, V(0.003) = 5.771, V(0.0072) = 4.856, giving 592 SWU, or 5.2 SWU/kg. At x_t = 0.002: V(0.002) = 6.188, F/P = 7.31, product 136.8 kg (+21 %) for 885 SWU (+49 %). At x_p = 0.90: V(0.90) = 1.758, F/P = 213.6, product 4.7 kg for 896 SWU. Stage counts from `x_n = x_0·1.0043ⁿ`: ln(0.04/0.0072)/ln(1.0043) = 400 stages to 4 %, and ln(138)/ln(1.0043) = 1,148 to 99 %, against about 2.2×10³ when the factor is applied to the ratio x/(1 − x). Burnup: 113.5 kg at 45 GWd/t = 5,110 MWd thermal; at 172.3 MeV per fission, 1 MWd consumes 1.2 g of ²³⁵U by fission, so 4.54 kg would give 3,780 MWd by fission alone and about 3,200 MWd once a capture-to-fission ratio near 0.17 is applied, leaving more than a third of the energy to bred plutonium. Waste: ten half-lives of a 30-year nuclide is 300 years and a factor of 1,024; discharge rate 3,000 MW × 365 d × 0.9 availability = 985 GW-days, ÷ 45 GW-days per tonne = 21.9 t of spent fuel per year for a 1 GW-electric station. Service: 113.5 kg of 4 % fuel holds 4.54 kg of ²³⁵U, which at Murphy's 4.5 g per person-year is about 1,000 person-years. ## External links - [*Energy and Human Ambitions on a Finite Planet*](https://open.umn.edu/opentextbooks/textbooks/energy-and-human-ambitions-on-a-finite-planet) (Murphy, 2021), Chapter 15 — the isotopic abundances, the breeder chain half-lives and the waste window used here - [*General Chemistry: Principles, Patterns, and Applications*](https://open.umn.edu/opentextbooks/textbooks/general-chemistry-principles-patterns-and-applications) (Averill & Eldredge, 2011), Chapter 10 — Graham's law and the UF₆ cascade - [*Future Energy: Opportunities & Challenges*](https://open.umn.edu/opentextbooks/textbooks/future-energy-opportunities-challenges) (Kerlin, 2013), Chapter 8 — the fuel cycle as an engineering chain - The Wikipedia pair's *External links* section lists the agency and industry sites for the fuel-cycle stages described above. <!-- MATTERSIM:BEGIN g33 — Matter & Energy Cluster microsim (framework build, specs/sims/Nuclear_fuel_cycle.json); do not hand-edit inside --> **Microsim — three.js (Wikitube framework):** *Nuclear fuel cycle* <div class="wt-sim" data-src="https://wikitube-3d-microsims.netlify.app/matter/Nuclear_fuel_cycle.html" data-title="Nuclear fuel cycle"></div> *Built from `MICROSIM_GUIDE/specs/sims/Nuclear_fuel_cycle.json`; part of the [[PORTAL_Matter|Matter portal]] spine (section sims and See-also variants).* <!-- MATTERSIM:END --> ## Wikipedia : Wikitube **Strict pair:** [Wikipedia](https://en.wikipedia.org/wiki/Nuclear_fuel_cycle) : [Wikitube](https://en.wikitube.io/wiki/Nuclear_fuel_cycle) · pinned revision [1366424540](https://en.wikipedia.org/w/index.php?oldid=1366424540) · 2026-09-11 ## Previous hub tags Hubs: `Life_Physics`. Portals: [[PORTAL_Energy]]. --- *Matter & Energy Cluster child articles, wave 1 · 2026-09-11 · drafted · Energy row E50 · sim pending (matter/Nuclear_fuel_cycle).*