Fuel form
Fuel dissolved in salt
Fuel dissolved in a fluoride or chloride salt, circulating as a liquid. No fuel fabrication, no cladding, no assembly geometry to maintain.
01 / What thorium is
A different starting point for the fuel cycle
Thorium is a naturally occurring metal, roughly three to four times more abundant in the earth's crust than uranium. It is not itself fissile; it cannot sustain a chain reaction on its own.
In a reactor, thorium-232 absorbs a neutron and converts to uranium-233, which is fissile. The thorium acts as fertile material and the reactor breeds its own fuel as it operates. That is a different starting point from the conventional cycle, which begins with uranium that must be mined, converted and enriched before it can be used.
The consequence is a shorter front end. No enrichment cascade, no separative work, and a fuel supply that is not constrained by the same bottlenecks now limiting conventional expansion.
One qualification matters. Because thorium is fertile rather than fissile, a reactor still needs a fissile starter, enriched uranium or plutonium, to reach criticality the first time. The cycle reduces dependence on enrichment as it runs. It does not remove it at startup.
Conventional cycle
- Starts with mined uranium
- Requires enrichment
- Fissile from the outset
- Established supply chain and licensing
- Long-lived transuranic waste
Thorium cycle
- Starts with fertile Th-232
- Fissile starter required at first criticality
- Breeds fissile U-233 in-reactor
- Supply chain not yet built out
- Different waste profile; U-232 handling constraints
02 / Delivery mechanism
Molten salt as the delivery mechanism
Thorium can be used in several reactor types. The molten salt configuration suits it best, because the fuel is dissolved in the coolant rather than fabricated into solid assemblies. The characteristics below belong to the reactor class, as demonstrated at Oak Ridge between 1965 and 1969.
Operating pressure
Near atmospheric
The salt boils far above operating temperature, so the reactor does not require a high-pressure vessel or containment sized for a pressure excursion.
Thermal output
High outlet temperature
High outlet temperature suits industrial process heat, hydrogen production and desalination, not only electricity.
Shutdown behaviour
Move the fuel to safety
Because the fuel is liquid only while hot, molten salt designs can be shut down by removing the fuel from the core geometry rather than by cooling it in place. At Oak Ridge this was a freeze plug that melted and allowed gravity drain to a passively cooled tank. Other designs achieve the same end by other means.
Refuelling
Flexible operation
Fuel can in principle be added and fission products removed during operation, rather than through a shutdown and reload cycle.
These are characteristics of the reactor class, not specifications of any particular design. Performance for a specific reactor depends on materials selection, salt chemistry and the licensing basis, none of which are settled across the industry.
03 / Demonstration history
Not a new idea. An unfinished one.
A molten salt reactor ran for four years at a United States national laboratory. It was shut down for programme reasons, not technical ones, and the work was never resumed here.
1954
The Aircraft Reactor Experiment at Oak Ridge runs on molten fluoride salt, proving the fuel form works.
1965
The Molten-Salt Reactor Experiment reaches first criticality on 1 June. Graphite moderator, Hastelloy-N vessel, circulating fluoride fuel salt.
1968
On 2 October the MSRE becomes the first reactor in history to go critical on uranium-233, the fissile product of the thorium chain. AEC Chairman Glenn Seaborg took the controls.
1969
Nuclear operation concludes on 12 December after more than 13,000 hours at full power. Post-operation findings: the fuel salt was immune to radiation damage, the graphite was not attacked by the salt, and Hastelloy-N corrosion was negligible.
1973
The AEC withdraws funding. Oak Ridge had proposed a demonstration programme at $350 million over eleven years; the competing liquid-metal fast breeder programme was on course to spend roughly $400 million per year by 1975.
1976
The programme is formally cancelled on budget grounds. The reactor has been dormant since.
2023
China's TMSR-LF1 reaches criticality, built in part on declassified Oak Ridge data, following a reported national programme investment of over $444 million since 2011. It remains the only operating thorium reactor in the world.
Alvin Weinberg, who directed Oak Ridge through the programme, described the outcome plainly: a successful technology dropped because it was too different from the main lines of reactor development.
04 / Intellectual property
What we hold
Utah Green Energy Technologies is the assignee of record on six granted patents covering a molten salt reactor architecture. The numbers are below. They are public documents and we would rather you read them than take our description of them.
United States
10,283,223United States
10,008,293United States
10,276,269United States
10,283,224United States
10,515,727Europe
EP 3 144 938All six derive from a single application filed 18 September 2015 and share that priority date. The claimed architecture is a graphite core carrying sectional fuel wedges, with power controlled by rotating the core within its housing so the fuel ports open and close, and by varying the core's angle to use gravity on the flow. Because the wedges are built in sections rather than machined as a single piece, core length is not constrained by manufacturing.
05 / Programme status
Where the programme is
Stated plainly. The distance between a patented architecture and a licensed reactor is where most claims in this field fail, and we would rather be measured against a real position than a flattering one.
Stage 01
Design and IP
Complete. Six granted patents, listed above, held as assignee of record.
CompleteStage 02
Independent technical review
Not commenced. Review of the design by a national laboratory or university partner is the next milestone. Nothing stated on this page depends on a review that has not happened.
Not commencedStage 03
Licensing pathway
In evaluation. 10 CFR Part 53 took effect on 29 April 2026, the first technology-inclusive NRC framework. It is optional, sitting alongside Parts 50 and 52 rather than replacing them.
In evaluationStage 04
First deployment
Ahead. Site selection and offtake structuring alongside the technical programme rather than after it.
AheadDesign characteristics described on this page reflect the current design basis and are subject to change through detailed engineering and regulatory review. No regulatory approval has been sought or granted for any configuration described here. No reactor has been built. Detail is available under NDA to qualified counterparties.
06 / Open work
What is not solved
Thorium is not a finished technology, and any programme claiming otherwise is worth reading sceptically. These are the real constraints, and they are where credible effort goes.
Materials
Qualification at temperature
Molten fluoride salts are corrosive at operating temperature. Alloy selection and qualification for a multi-decade service life remain an active research problem across the entire field. The longest operating record in existence runs to about four years.
U-232 handling
Remote operations
The thorium cycle produces uranium-232 alongside U-233. Its decay chain emits hard gamma radiation, which complicates fuel handling and reprocessing and requires remote operations.
Supply chain
Build the front end
There is no commercial thorium fuel supply chain. Monazite processing, salt production and fuel qualification would all need to be built out to support deployment at scale.
No molten salt reactor has generated electricity at commercial scale anywhere. That is the honest state of the field, and it applies to every programme in it, including ours.
07 / Safety by design
Make normal physics do more of the work
Safety is not a layer added after the reactor is designed. The objective is to make the plant's normal physics reduce the number and severity of credible accidents, then verify every claim through detailed engineering, testing and regulatory review.
Pressure
Operate near atmospheric pressure
A liquid fuel salt does not require the high operating pressure used by a conventional water reactor. Lower pressure reduces the stored energy available to drive a pipe break, but materials, boundaries and containment still require qualification.
Shutdown
Let gravity move the fuel to safety
The design basis uses the fuel's liquid-to-solid temperature behaviour to support a drain function during a loss of power or over-temperature event. A passive feature is only a safety feature once its reliability and failure modes are demonstrated.
Containment
Keep the radioactive inventory bounded
Fuel inventory, salt chemistry, drain tanks and barriers are treated as one containment problem. The final arrangement must control releases across normal operation, design-basis events and beyond-design-basis conditions.
Defence in depth
Use independent layers
Passive characteristics do not replace monitoring, shutdown systems, shielding, physical barriers or emergency planning. Those layers must be independent where practical and assessed against the licensing basis for the completed plant.
These are design principles, not a claim of regulatory approval or demonstrated plant performance. No configuration described here has been built, tested at power or licensed.
Continue the conversation
The technology is proven. The programme is the work.
We are building the technical, licensing, supply and capital relationships required to move a thorium fuel cycle from demonstrated science toward energy production.