China Says It’s Closing in on Thorium Nuclear Reactor

With prototype reportedly firing up in September, country teases commercial thorium power by 2030

3 min read
Thorium on the periodic table

Thorium on the periodic table of elements.

Klaudia Kilman/Alamy

There is no denying the need for nuclear power in a world that hungers for clean, carbon-free energy. At the same time, there's a need for safer technologies that bear less proliferation risk. Molten salt nuclear reactors (MSRs) fit the bill—and, according to at least one source, China may be well on their way to developing MSR technology.

Government researchers there unveiled a design for a commercial molten salt reactor (MSR) that uses thorium as fuel, the South China Morning Post reported recently. A prototype reactor, the paper said, should be ready this month for tests starting in September. Construction of the first commercial reactor being built in the Gansu province should be complete, they noted, by 2030.

If all goes well with the prototype, says a report in Live Science, the Chinese government plans to build several large MSRs. According to the World Nuclear Association, the country is eyeing thorium MSRs as a source of energy especially for the northwestern portion of the country, which has lower population density and an arid climate.

MSRs are attractive for arid regions because instead of the water used by conventional uranium reactors, MSRs use molten fluoride salts to cool their cores. Uranium or thorium fuel can be mixed into the coolant salt. Thorium MSRs have the advantage of being more abundant and cheaper.

China's experimental reactor won't be the world's first. Researchers at Oak Ridge National Laboratory (ORNL) pioneered thorium-based MSRs in the 1950s for nuclear aircraft propulsion as part of the Manhattan Project. A 7.4 MWthexperimental reactor operated at the laboratory over a period of four years—although only a portion of its fuel was derived from uranium-233 bred from thorium in other reactors. This MSR technology was eventually shelved because the Pentagon favored the uranium fast breeder reactor, says Charles Forsberg, Principal Research Scientist at MIT's department of Nuclear Science and Engineering and former nuclear researcher at ORNL.

Scientists in China are now building on the same basic MSR technology developed at ORNL. The Chinese government had a small, short-lived knowledge exchange program with ORNL. But most of the thorium reactor-related intellectual property from ORNL is in the public domain, and China appears to have made some use of it. "The real data mine is the thousands of published reports in 1960s and '70s that are found in the open literature," Forsberg says.

Plus, recent technology developments have made it more feasible to build MSRs, he adds. This includes modern instrumentation that can unveil exactly what goes on in the reactor—but also includes equipment that finds parallel use, such as high-temperature salt pumps used in today's concentrated solar power plants that store heat via molten salts.

The real data mine is the thousands of published reports in 1960s and '70s that are found in the open literature.

"So now if you want to build a salt pump for a MSR you go talk to your local friendly CSP pump suppliers for a slightly different salt composition," Forsberg says. "That makes a tremendous difference in your development program. You have fifty years' worth of new technology to tap into."

But even though France, India, Japan, Norway, and the U.S. are all reportedly working on thorium nuclear reactors, none of these countries have outlined plans for commercial reactors yet. A handful of private sector developers are working hard to deploy MSRs within the next decade. The closest is probably Alameda, Calif.-based Kairos Power, which plans to have a 50 MW demonstration reactor operational in Oak Ridge, Tenn. by 2026.

Yet China leads global MSR research, according to the World Nuclear Association, and it's no surprise that the country is forging ahead faster, Forsberg says. The country's talent pool in nuclear engineering, he says, is quite substantial. "You put a lot of talented people on a project, and it works," he says. "They'll be successful even if it takes them a while."

This article appears in the October 2021 print issue as "China's Thorium Gambit."

The Conversation (7)
Carl Page
Carl Page19 Aug, 2021

Canada has MSR companies too. Terrestrial Energy.

USA has Thorcon Power.

There are several others. ARC nuclear in new Brunswick.

Ultra safe nuclear.

Molex in UK.


Designs differ but they all discard H2O in the reactor chamber which is an explosive two ways in the reactor environment. steam or H dissociation.

Don't be concerned about a U233 bomb. That would be a crazy impractical way to make one which is a primary reason this fuel cycle was passed over in the cold war. No stealth is possible due to distinctive hard gamma. Let's not let ridiculous fears stop progress in real anti proliferation progress. Like burning as fuel existing warheads and partly burned fuel from LWR. (Often called Waste because the LWR can't burn the 95% left over...) But the MSR can. So there is very little waste left and nothing long lived.

4 Replies
lionel king
lionel king25 Sep, 2021

so what

Christopher Aoki
Christopher Aoki06 Aug, 2021

In the IEEE Spectrum article "China Says It's Closing In On Thorium Nuclear Reactor" [1], Prachi Patel wrote:

"A handful of private sector developers are working hard to deploy MSRs within the next decade. The closest is probably Alameda, Calif.-based Kairos Power, which plans to have a 50 MW demonstration reactor operational in Oak Ridge, Tenn. by 2026."

According to Kairos Power's technology web page [2] the Kairos Power reactor is not an MSR in the same senseas the original ORNL Molten Salt Reactor Experiment (MSRE).The MSRE reactor used a molten fluoride salt as both coolant and fissile fuel, whereas the Kairos Power reactor uses molten fluoride salt strictly as a coolant. The Kairos reactor fuel is a high-temperature solid ceramic made of Tristructural-isotropic (TRISO) granules containing uranium oxide fuel.

Significantly, neither the historic ORNL MSRE reactor nor the proposed Kairos reactor use Thorium as fuel, which appears to be the chief breakthrough of China's MSR design. I suspect that China's MSR design may be less constrained by regulatory agencies than MSR designs from other nations, which are strictly forbidden from use of design features that might conceivably be exploited for weapons proliferation purposes.

The primary example of such a feature is continuous online chemical separation of the fertile isotope Pa233 as an intermediate by-product of breeding fertile Th232 into fissile U233 . The continuous online separation of Pa233 is said to be necessary in order to prevent accumulated Pa233 from absorbing so many free neutrons that the ongoing U233 fission chain reaction [presumably thermal] grinds to a halt while waiting for the Pa233 to beta-decay into fissile U233. [3].

If breeder-generated Pa233 were separated, diverted, and removed from the reactor, the eventual result would be ready-made weapons-grade U233. China may have a unique reactor security regimen that protects this material from clandestine diversion or they maysimply choose to ignore it. Or their technology may have an undisclosed feature that solves the Thorium breeding problem without creating a weapons proliferation problem. Etc.


[1] "China Closing In On The Thorium Nuclear Reactor",Prachi Patel, IEEE Spectrum, 04 Aug 2021.

[2] Kairos Power Technology web page:

[3] "Advanced Isn't Always Better", by physicist Dr. EdwinLyman, Union of Concerned Scientists (UCS). See box 8,"Protactinium And The Thorium Fuel Cycle", PDF page 105.