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Guides explain the technology and the terms. Tutorials show how to answer a question with this site.
14 guides and 5 tutorials. Single terms are defined in the glossary.
Fusion
- How fusion works
What nuclear fusion is, which fuels it can use, the temperature, density and confinement it needs, and why no machine has yet turned it into electricity.
- Fusion approaches compared
Every family of fusion machine, how each holds its fuel, the best result this dataset holds for it, its main unsolved problem and the organisations pursuing it.
- Fusion fuels, tritium and neutrons
Deuterium-tritium, deuterium-deuterium, deuterium-helium-3 and proton-boron-11 compared: what each reaction releases, where the fuel comes from, and why aneutronic is a relative term.
- Fusion milestones: what has happened and what is promised
The milestones that mark progress towards fusion power, which have been reached and when, and what fusion organisations say they will do next, in their own words.
- Commercial timeline of fusion power
Six fusion power plants are on record, all still planned. The only dated electricity purchase is Helion's May 2023 deal to supply Microsoft from 2028.
Fission
- How fission reactors work
How a fission reactor sustains a chain reaction, what the moderator, coolant and control rods do, why delayed neutrons make control possible, where decay heat comes from, and what passive safety does and does not mean.
- How nuclear reactor licensing works in the US, Canada and the UK
The separate permissions a fission reactor needs before it can be built and run, what each one allows, how fusion is regulated differently, and how to read the licensing page.
- Reactor types explained
The three questions that classify any fission reactor, and how pressurised water, boiling water, heavy water, gas-cooled, salt-cooled, molten-salt, sodium, lead and heat-pipe reactors each answer them.
- Nuclear fuel explained
Where reactor fuel comes from, what enrichment does, where the lines between LEU, LEU+, HALEU and HEU fall, how TRISO, MOX and thorium fuels differ, and why HALEU supply limits advanced reactors.
- Fusion and fission compared
How fusion and fission differ in the physics, the fuels, the neutrons, the waste, the safety case and how far each has come, set side by side with the numbers.
Modular reactors
- Small modular reactors
What makes a reactor a small modular reactor, where the IAEA draws the size lines, why size is judged per unit rather than per plant, which ones actually operate, and why their cost claims are not yet proven.
- Microreactors
What microreactors are, how heat-pipe, gas-cooled and sodium-cooled designs work, what they are meant for, why most need HALEU or TRISO fuel, and where the leading projects actually stand.
Reading the benchmark
- Fusion gain explained: why there is no single Q
The six kinds of fusion gain this benchmark records, what each one divides by, and how one NIF shot is both a gain of 1.5 and a gain below 0.01.
- The triple product and the Lawson criterion
What density times temperature times confinement time measures, how far the best plasmas are from ignition, and how to read the benchmark's triple-product leaderboard.
Using the site
- Find companies by reactor type Tutorial
How to list the companies working on one kind of fusion machine or fission reactor, using the companies directory, the technology pages and the device table.
- Read a row on the benchmark and leaderboards Tutorial
What each column on the benchmark and leaderboard pages means, what achieved, claimed and planned tell you, and how to follow a figure back to where it was published.
- Compare approaches and devices Tutorial
How to use the comparison pages to set two approaches side by side, and the device table and leaderboards to compare individual machines.
- Check a source Tutorial
Where each figure's sources are shown, what the independence labels mean, how archived copies work, and how to tell when several sources are really one.
- How we verify a figure Tutorial
The steps every record goes through, from fetching a source to review, what the confidence and verifiedAt fields mean, and how corrections are recorded.