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Dr Ben Miles explores a thorium reactor's cheaper-than-coal ambition

His Copenhagen Atomics visit gets into the salt purification, stainless steel and layered design behind a proposed container-sized heat supplier.

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Dr Ben Miles Story of November 11, 2026Trari Newsroom

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Why this story? One of the most watched videos since yesterday, with 313,828 views.

This Nuclear Reactor Runs on Thorium and Could Be Cheaper Than Coal?

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1:52Thorium must absorb a neutron and transform into uranium-233 before it can supply fissile fuel.
6:01Pedersen explains how thorium salt, a fissile core and heavy-water layers share the reactor's neutron budget.
16:44Stubsgaard presents purified-salt test samples and explains the company's proposed solution to stainless-steel corrosion.
20:00Lithium isotope separation removes a neutron absorber while producing material useful for breeding fusion fuel.
25:51The company targets energy cheaper than fossil fuels; this is a cost goal, not a commercial result.
26:45Denmark's nuclear-generation ban takes the Balder test project to Switzerland's Paul Scherrer Institute.

An onion made of stainless steel is an unlikely place to look for cheaper energy. But inside Copenhagen Atomics' workshop, Dr Ben Miles finds a reactor prototype whose layers each have a job: breeding fuel, slowing neutrons and keeping very hot molten salt away from much cooler water.

His Danish lab visit has drawn about 314,000 views since yesterday. The question in the title, "This Nuclear Reactor Runs on Thorium and Could Be Cheaper Than Coal?", leads into something more concrete than a promise of abundant fuel: what would it actually take to build the machine?

Miles starts with the catch. Thorium isn't itself fissile, so it must absorb a neutron and pass through a sequence of transformations to become uranium-233, which can sustain fission. The design needs enough neutrons both to keep that reaction going and to make replacement fuel. Materials that absorb them can upset that delicate balance.

That is where ordinary stainless steel becomes interesting. Molten fluoride salts have historically corroded it, while specialist alloys bring costs and neutron losses of their own. CTO Aslak Stubsgaard shows test samples and explains the company's approach: remove moisture and oxide impurities from the salt so thoroughly that, he says, corrosion becomes insignificant.

Viewers are picking up on those engineering obstacles, particularly corrosion and lithium purification. Another thread follows a surprising connection: separating lithium isotopes for this fission design can also produce material useful for breeding tritium for fusion reactors. The onion, meanwhile, has inspired its own Shrek joke.

The cheaper-than-coal proposition remains the company's target, not a demonstrated commercial result. CEO Thomas Jam Pedersen explains that Copenhagen Atomics intends to sell heat rather than build entire electricity plants, supplying hot molten salt to customers' heat exchangers. Its maintenance plan includes draining the salt and replacing the internal steel core.

For the Danish company, the route to a working test reactor leads abroad. Miles closes the visit by explaining that Denmark's ban on domestic nuclear electricity generation has taken its Balder test project to Switzerland's Paul Scherrer Institute.

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