Before anybody gets too excited, it's better to understand what exactly happened.
China ran an experimental reactor that achieved some conversion of thorium into uranium. More precisely, the conversion ratio was 0.1 [1]. This means that for each new fissile atom generated from thorium (i.e. uranium-233) 10 atoms have been burned from the original fissile inventory.
Now, conversion happens in every nuclear reactor. Some new fissile material (generally Pu-239) is generated out of "fertile material" (generally U-238). And, surprisingly, that conversion ratio is quite high: 0.6 for pressurized light water reactors and 0.8 for pressurized heavy water reactors [2].
What China has achieved therefore is well below what is business as usual in regular reactors. The only novelty is that the breeding used thorium, rather than uranium.
Is this useless? No, it is not. In principle increasing the conversion ratio from 0.1 to something higher than 1.0 should be doable. But then, going from 0.8 in heavy water reactors to more than 1.0 should be even easier. Why don't people do it already? Because the investment needed to do all the research is quite significant, and the profits that can be derived from that are quite uncertain and overall the risk adjusted return on investment is not justified. If you are a state, you can ignore that. If China continues the research in thorium breeding, and eventually an economically profitable thorium breeder reactor comes out of that, the entire world will benefit. But the best case scenario is that this would be three decades in the future.
The real killer feature isn’t "more thorium than uranium" (thorium is already 4× more abundant). The real win is that thorium MSRs can eat the existing mountain of "spent" fuel rods from regular reactors and turn what we currently call high-level waste into electricity while leaving waste that’s safe in a few hundred years instead of tens of thousands. That’s hundreds of thousands of tons of "waste" suddnely becoming centuries of clean fuel. That alone flips the economics on its head.
Also: passive safety (the thing just drains and freezes if anything goes wrong), no pressure vessel, tiny physical footprint, way less long-lived actinides, and U-233 is basically proliferation-proof because of the hard gamma from U-232.
Uranium feels cheap and plentiful right now exactly the way oil felt infinite in the 1950s. China is playing the long game, and this little 2 MW rig lighting up and breeding U-233 last month is the “Sputnik moment” for the thorium cycle.
So...Three decades? Maybe if the West keeps sitting on its hands. China says 10 MW by 2030 and 100 MW demo by 2035. I wouldn’t bet against them.
Literally almost all the waste that’s ever been generated is stored on site at the nuclear power plants where it was created. That’s how little of it there is.
Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.
2. There is no high level waste that is both very dangerous right now, and will remain so for tens of thousands of years. It’s either highly radioactive for not very long, or not very radioactive for very long, but never both.
How do these myths persist in otherwise educated people.
> Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.
Yeah, it’s really easy to forget how dense these materials are. A jug of milk (4L/1gal) weighs 4kg/8.8lb. Milk has about the same density as water, 1g/cm^3. Uranium has a density around 19g/cm^3, making that same gallon jug weigh 76kg/167lb. A metric ton of uranium (1000kg) is about 13 gallons.
> Talking about “thousands of tonnes” of nuclear waste is comically misleading when you realise how tiny the volume is.
You’re mixing mass and volume here. From what I can tell, their numbers were essentially right. Are you saying we don’t have thousands of tonnes of nuclear waste produced?
Long life, high activity nuclear waste represents less than 3500m3 (one Olympic swimming pool), and this, since the start of civil nuclear electrical production in the 50's. World wide.
20 swimming pools of total waste isn't that impressive. I don't want to live near that, but I'm sure I'd we can find a place to put that in that will have minimal impact on people's lives.
Exactly. The waste isn't really a problem. But it doesn't have to be waste. That's the point. All that U235 in 'spent' silos? You can get 60x - 100x its OG power feeding it to nextgen reactors. So cool
I guess you mean the "super hot for centuries" minor actinides (Np-237, Am-241/243, Cm-242/244/245 etc..)? These are less than 1% global waste, but next gen reactors can still eat them. The majority of waste (95%+) is U-235, then Pu, which nextgen also eats.
Many magnitudes of order less than any of: all the steel, glass, aluminium, wood, or plastic, ever produced, and we aren’t yet drowning in cubic miles of any of those.
> The real win is that thorium MSRs can eat the existing mountain of "spent" fuel rods from regular reactors
That's not true.
The spent fuel can burn in fast reactors. There are hundreds of molten salt reactor designs (see for example [1]), and some of them are fast reactors.
But thorium MSR are not fast. That's the attraction of thorium, it can undergo transmutation (into protactinium, which then decays into fissile uranium-233) using thermal neutrons. Nobody is proposing thorium MSR as a solution to burn spent nuclear fuel.
> So...Three decades? Maybe if the West keeps sitting on its hands.
The West does not keep sitting on its hands. There are dozens, maybe hundreds of nuclear startups in the West, and they are actually making progress.
However, thorium is hard. Very hard. Breeding plutonium from uranium is much easier than breeding uranium-233 from thorium.
Here's a good post [2] about the thorium myths written by a former active HN forum member, Nick Touran. It's a good read. But, now, for an even better understanding, you can just ask ChatGPT, or any other LLM, how thorium breeder reactors compare to plutonium breeder reactors, and which technology is closer to reality.
This can be done in usual breeders like superphenix or bn800. What china wants to experiment with is continuous filtration instead of using breeding+purex/pyroprocessing. Still, it's nothing more than an experiment, china is rather slow with nuclear compared to french messmer and sweden in the past
Fundamentally the problem is that Uranium is so damn energy dense and abundant enough that there's little need to set up these complicated recycling systems. If we start to run out of Uranium then this technology starts to look appealing, but in the modern day it just doesn't make economic sense.
> Uranium is so damn energy dense and abundant enough that there's little need to set up these complicated recycling systems
Uranium is abundant, but not homogenously so [1]. (China has some. But not a lot. And it's bound up expensively. And it's by their population centres.)
For the Americas, Europe, Australia, southern Africa and Eastern Mediterranean, burning uranium makes sense. For China, it trades the Strait of Malacca for dependence on Russia and Central Asia.
Uranium can be stockpiled for years in advance, relatively easily. Enough to tide over a small war while you're setting up domestic production. And China should have enough low-grade ores for that.
Uranium is better for Chinese energy security than oil. But this still leaves China at Moscow's mercy. That's not too differet, energywise, than the situation is now.
> Uranium is far, far energy denser than any fossil fuel, and thus much easier to stockpile
Sure. That doesn't remove stockpiles' inherent disadvantages: finiteness and vulnerability. Relying on uranium stockpiles would immediately put China at a known limit in a war of attrition that wouldn't constrain their adversaries.
A sufficiently large stockpile of uranium gives China time to simply pivot away from depending on imported Uranium (either by building new mines locally or building out solar or such). An equivalent stockpile of oil simply isn't feasible, if only because oil is usually used directly and not via a source-agnostic electrical grid.
I know. I am not saying I got the order of magnitude exactly right, just pointing out beyond a certain threshold the size of the stockpile doesn't matter. I suspect that if a nation state puts its mind to it, stockpiles great enough to last a war are totally possible.
That's not a stockpile, they have to extract and refine it to use it. Russia understood it the hard way with the refineries attacks.
And no, oil is more expensive (especially nowadays) to extract than uranium.
There's a reason nobody ever became rich with a uranium mine, all the value is in the plant and the market price barely covers extracting it, some mines even closed because of the price being too low.
We're not talking about ore, rather fuel. Uranium ore might be inexpensive, I don't know, but converting that ore into fuel is not an easy task. I'm guessing that the reason it's not profitable is that so little of it is actually needed, relative to oil.
There's not that much Uranium actually that's economically sensible to extract. The NEA says in their 2024 report on Uranium [1]:
> Considering both the low and high nuclear capacity scenarios to 2050 presented in this edition, and assuming their 2050 capacity is maintained for the rest of the century, the quantities of uranium required by the global fleet – based on the current once-through fuel cycle – would likely surpass the currently identified uranium resource base in the highest cost category before the 2110s.
Their "high" scenario assumes having a bit more than double of today's capacity by 2050; today we have about 4-5% supply from nuclear energy worldwide.
It's a bit different. Higher demand will lead to higher price, opening more options to mine. Now uranium is too cheap to open new mines and exploration
And I hate to pollute this thread with more AI fear-mongering, but AI inference is already showing its effects on the energy sector and it is expected to grow very rapidly. Energy demands may likely grow at a stronger rate than initially expected.
Hm, is that really the case? Nextgen reactors are not just about lowering the cost of U. Or "saving the environment" from waste. Bonuses, sure. Real strength is increasing efficiency, which means: 1) lower buildout costs, 2) faster time to first iphone charged, 3) smaller, safer designs. They're a way around the giganto-plants of the past, on the way to making nuclear power the ubiquitous reliable utility it should be.
I also like to think of U/nuclear as "Civilizational thinking" - it's the only solid power we can trust to stay by us through 10,000s of years, through cataclysims, and planet migrations, and it's ideal (before we find something more abundant, dense, and reliable) to take us from Earth, to a multi-planet, local-cluster exploring species, I think.
The reason TMSR is appealing is that U-233 is hard to use for weapons purposes because it produces a lot of gamma radiation, which makes it hard to work with. There is also the claim that TMSRs are much safer designs than is possible with Uranium. It's possible that if TMSRs were mass produced that we could see them installed in many countries where we don't want to see Uranium or Plutonium reactors for proliferation reasons.
With a Uranium-based reactor you need a) a source of enriched Uranium (see proliferation risks), b) inspectors to check that you're not post-processing fuel rods to extract Plutonium.
With Thorium if the operator country wants to extract the U-233 you think "maybe let them, they won't like it".
With classic pwr rods can't be used for weapons because of parasitic isotopes. At best you need to run the reactor in a specific way that would trigger global attention looking at power fluctuations. And still it'll not be easy afterwards.
You can buy enriched uranium from others.
With th- I'm not sure but don't you need enriched material anyway to kickstart it?
It's not uniformly distributed. Countries like India, for ezample, has an abundance of Thorium but they have to buy Uranium for use in any large scale application.
Sorry, but there are quite a few things you are missing. Nuclear engineering is well, nuclear engineering. The first big difference is that you can use the Thorium in a liquid fueled reactor instead of a solid fueled one. This allows you to burn far more of the fuel. For example, 2-4% of a solid fuel rod would fission, while in a liquid fueled reactor you can get to 90+%. This is good economically for 2 reasons: 1) more energy per unit of fuel and 2) the waste lasts far less time.
There are also other advantages of a liquid fueled reactor. The big one is that it is far easier to run because it self regulates. When a liquid heats up it expands (slowing the reaction) and when it cools it contracts (speeding up the reaction). So its safer to run, makes less waste and gets 20+X more power per unit of fuel.
There is one final thing to know about this stuff. A nuclear reactor is several billion in infrastructure supporting reactors that cost 10s of millions using a fuel load that costs less than your car. The way we scale and handle nuclear reactors just makes no sense economically. Each NPP is custom and they are built so rarely that everything has to be custom made. When you start building stock reactor designs with consistent supply chains, the cost goes way down. And most of the cost is lawsuits, lobbyists and PR. For developed countries, using or not using nuclear power is a political choice. One that we have been making badly. When you realize that the only real choices for baseload are FF and nuclear, the real political situation makes sense. Once again, the cause is just the excuse, not the real issue.
> When you realize that the only real choices for baseload are FF and nuclear, the real political situation makes sense.
That’s not really accurate. Many countries already meet a substantial portion of their baseload power requirements with renewables and are building out more and more renewable generation because it is cheap and fast to build.
This requires dispatchable backup generation to cover low wind periods, but that may only need to run a few weeks a year. This is by far the cheapest and fastest way to get to 90% carbon free power since most of the cost in gas generation is the fuel itself rather than the capital for the plant.
Nuclear is the opposite so cannot economically fill that role so it seems little is likely to be built.
> Nuclear engineering is well, nuclear engineering.
Not sure I get what you are trying to say. Are you saying that you are a nuclear engineer and I am not? Because, frankly, the rest of your comment does not read as one written by a nuclear engineer.
There's also the choice to match our energy consumption dynamically to intermittent power sources (e.g. solar), reducing the baseload demand. This is entirely orthogonal to decisions about where the baseload generation should come from.
doesnt make a difference to the economics of a nuke plant. Fuel consumption is a tiny fraction of the cost of nuke power, its almost all fixed cost - amortized construction costs, operations, etc. You need to run it at as close to 100% always to have any chance at payback & economical $/kw. Thats why they arent getting built.
We really do. Nuclear waste is less toxic than plenty of trash we just bury. And calling it "waste" is a bit reductive, given it almost certainly becomes valuable to reprocess within another century or two.
Radioactive waste is decidedly nasty stuff, but the total volume of it is tiny. There are plenty of chemicals that are just as nasty that were simply buried in the ground in much larger quantities over the years with nary a peep from the population. Nuclear waste is a political problem not a technological one.
The crazy part is that people want to insist that the sites need to be absolutely safe even if they aren't maintained for 1,000 years, but by that point the radioactivity would be no more than the base ore anyway so demanding these extended timelines doesn't make anybody safer. They're just red tape.
It's peculiar that it's a political problem in pretty much every country though? I know Finland is well on its way for long term storage but that's the only example I know of.
There's also quite a few cases where it is a technical problem. Gorleben in Germany for example.
Joking here since it would be impractical, but I guess you can bury it under my house. I'd not be bothered at all to live on top of a modern nuclear waste deposit like Finlands.
Waste from modern nuclear power plants seems to be a giant nothingburger. And yes, I came from the other side but flipped as I learned more about the technicalities, how Finland has solved it and how near you need to get hurt.
My understanding is that reactors will use that plutonium just fine, so the energy you get from a fresh fuel rod is almost exclusively from uranium fission but, as time goes on, an increasingly large share is from plutonium fission.
In principle, using Thorium would give you the energy from Thorium fission, then Uranium fission, then plutonium fission, which is pretty cool. However, I suspect you might hit an issue here where such a low conversion rate would make the reactor go sub-critical.
No, this is a misunderstanding of how fission works.
When a nuclear reactor is run with mildly-enriched Uranium, which is a mixture of Uranium 235 and Uranium 238, it forms a self-sustaining chain reaction with the Uranium 235 (which is fissile) and a load of the spare neutrons get absorbed by the Uranium 238 (which is fertile), converting it into Plutonium 239, which is also fissile. But most Uranium 235 reactors use a moderator which slows down the neutrons, which makes them more likely to cause fission in Uranium 235 but less likely to transmute Uranium 238 to Plutonium 239. So most modern reactors don't produce much Plutonium. In any case, the fission you get from Uranium and the fission you get from Plutonium is from different source materials. Once an atom is fissioned, it is split into smaller atoms and can no longer be fissioned.
Thorium isn't fissile, it's fertile. That is, if you fire a neutron at Thorium 232, you get Thorium 233, which decays to Protactinium 233, which then decays into Uranium 233, which is fissile. You then fire another neutron at Uranium 233, which then fissions into much smaller nuclei, giving you energy and the neutrons to do the above. The Uranium is no longer around after that to form Plutonium. There is no way to get any significant amount of Plutonium 239 from this, because that would require adding 7 more neutrons to the original Thorium 232 and having none of them trigger a fission event. The fissions that do occur don't provide 7 neutrons anyway, so it wouldn't be possible to get a self-sustaining conversion of a significant amount of Thorium into Plutonium for final fission even if the previous sentence weren't true - it would have to be enhanced with some other provider of lots of neutrons.
I'm getting impression that China is trying to position itself as scientific powerhouse before its massive industrial production scheme stops working. Smart move.
China ran an experimental reactor that achieved some conversion of thorium into uranium. More precisely, the conversion ratio was 0.1 [1]. This means that for each new fissile atom generated from thorium (i.e. uranium-233) 10 atoms have been burned from the original fissile inventory.
Now, conversion happens in every nuclear reactor. Some new fissile material (generally Pu-239) is generated out of "fertile material" (generally U-238). And, surprisingly, that conversion ratio is quite high: 0.6 for pressurized light water reactors and 0.8 for pressurized heavy water reactors [2].
What China has achieved therefore is well below what is business as usual in regular reactors. The only novelty is that the breeding used thorium, rather than uranium.
Is this useless? No, it is not. In principle increasing the conversion ratio from 0.1 to something higher than 1.0 should be doable. But then, going from 0.8 in heavy water reactors to more than 1.0 should be even easier. Why don't people do it already? Because the investment needed to do all the research is quite significant, and the profits that can be derived from that are quite uncertain and overall the risk adjusted return on investment is not justified. If you are a state, you can ignore that. If China continues the research in thorium breeding, and eventually an economically profitable thorium breeder reactor comes out of that, the entire world will benefit. But the best case scenario is that this would be three decades in the future.
[1] https://www.world-nuclear-news.org/articles/chinese-msr-achi...
[2] https://en.wikipedia.org/wiki/Breeder_reactor#Conversion_rat...