This is a passionate team working on a very hard problem. They have guts and skills. I've always loved microreactors for fringe remote power where people are willing to pay 20x more than normal diesel generator prices. Like Antarctica, remote bases, the moon etc.

Trying to make microreactors cheap is super hard. We've obviously tried it many times, the most relevant being the truck-mounted military microreactor ML-1 (the only closed-cycle direct gas turbine reactor ever operated) https://en.wikipedia.org/wiki/ML-1.

Shielding is hard. Even a small reactor this size needs like 8 ft. of high density concrete on all sides, or equivalent, plus 4-6" of a heavy metal like tungsten to take down the gammas. You can't just put it underground because the neutrons activate the dirt. Driving it off afterwards is borderline impossible because you generally have to put the spent fuel in robust canisters that can handle collisions, rollovers, and RPG attacks.

But the hardest part is fuel cost. This reactor uses medium-enriched ('HALEU') fuel, which is super expensive, and then it packages it into TRISO form, which is about 100x more expensive to fabricate than regular UO₂ fuel. On the plus side, it's super robust and can minimize the need for other safety systems. Those prices could both go down, conceivably, but the fab process is pretty intricate, and it's hard to bring down enrichment costs. In my analysis, the fuel cost alone nearly makes this kind of reactor uncompetitive with a diesel generator in almost all applications. So even if the reactor is free (because you build it on an assembly line?), you're still out of luck.

Then there's thermal strain. When you're a small reactor you have big gradients. This bends things. Neutrons make it worse. Then you have a tiny box with electronics in it getting absolutely hammered by neutron dose. That does bad things too.

I hope they can find a way to bring fuel costs way down. I really like the people at this company, and I really like nuclear power and want to see it used in many new applications. I just don't quite see the path yet.

▲ no_wizard 3 days ago | parent | next [-]

Wonder if much of the world didn't turn away from nuclear power they way they did since the 1960s, if we wouldn't have solved alot of problems like these already given research was stagnant (relative to other research in power generation) for a very very long time.

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acidburnNSA 3 days ago | parent [-]

It'd be a much different field if we had kept it up. I spend a lot of time in nuclear archival material, and facilities like CANEL in Middletown CT absolutely blow my mind. They had hundreds of people working on crazy reactor technologies. They were flowing white-hot lithium metal at 100 mph. But yeah we gave all that up. My friend wrote a pretty good article about this not long ago https://www.ans.org/news/2025-05-08/article-6961/hightempera...

	▲	binary132 3 days ago \| parent [-]
		In order for this to happen, making websites and mobile apps is going to have to get a lot less lucrative.

▲ cyberax 3 days ago | parent | prev | next [-]

> On the plus side, it's super robust and can minimize the need for other safety systems.

Can it survive 20 kilos of TNT planted by a terrorist?

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acidburnNSA 3 days ago | parent | next [-]

If they radiation shield it properly, I'd like to think so. That won't do anything to 8 ft of concrete plus 4" of tungsten.

Plus the fuel form holds in a lot of the fission products even when scattered around. It may overheat and release volatile fission products but I don't think it would be a widespread disaster no matter what.

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cyberax 2 days ago | parent | next [-]

Well, how about a 500 kg shaped charge?

And you can just remove the control rods and wait for it to melt on its own (meltdown-proof fuel isn't actually, well, proof). You'll get a nice contamination with volatiles (cesium and iodine), for the bonus points you can wait until the end of the fuel campaign to maximize the amount of transuranics.

I just don't think this is a viable option, except for very niche scenarios.

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Atotalnoob 3 days ago | parent | prev [-]

Could you reduce the amount of concrete by increasing the amount of tungsten?

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acidburnNSA 3 days ago | parent [-]

Not really. You have to stop neutrons and gammas. Concrete does neutrons but not gammas, tungsten does gammas but not neutrons.

You can also use water on neutrons or lead on gammas. There are many combos and composites.

Oh and neutrons cause more gammas when they get absorbed. Sometimes there are repeated layers, 3 or 4 times. If you have even tiny impurities in your shield you can get huge unexpected capture gammas

It's a rich tradition for reactors to start out with too little shielding though. Like the Japanese nuclear powered cargo ship Mutsu fired up for the first time, realized they didn't shield well enough, and spent 4 years fixing/retrofitting more shielding.

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LargoLasskhyfv 2 days ago | parent [-]

Is anybody considering the research into and use of metamaterials for shielding instead? Like 2D-twisted-hyperhexasomething?

	▲	acidburnNSA 2 days ago \| parent \| next [-]
		People are looking into it, but I don't think there's all that much promise. Fine structure of shielding doesn't really matter to an energetic particle that's blowing through meters of it. Gamma rays are stopped by electron density. Electron density requires high mass density heavy (high Z) nuclides. Neutrons are stopped by light nuclei via conservation of momentum, and by neutron absorbing nuclei like boron. If metamaterials can be made with higher density electrons in a way that's cheaper than lead and high hydrogen density that's cheaper than concrete, paraffin wax, or water, then I guess it could be interesting.
	▲	godelski 2 days ago \| parent \| prev [-]
		I used to work on novel shielding designs. There's some pretty interesting stuff out there but in the vast majority of situations it is just cheaper and easier to pour more concrete. To add to acidburn's comment, material choice is also highly dependent on the energy levels and particle types. At high energies you basically just maximize mass. At lower energies (more typical for reactors) you can start taking advantage of atomic cross-sections and electromagnetism. That's why they like borated concrete, high neutron cross-section, but only really effective for "thermal neutrons".

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whamlastxmas 2 days ago | parent | prev [-]

Can a skyscraper?

▲ AnthonyMouse 3 days ago | parent | prev | next [-]

I don't really get the "make it small enough to fit on a truck" thing. The main impediment for nuclear is cost, and then being able to build reactors on an assembly line would be a significant advantage. But how much of that advantage is retained if the product comes on more than one truck and the thing that comes is the reactor, the fuel and the turbines whereas the concrete gets poured on-site? It seems like that should get you nearly all of the cost savings from mass production but then you get a full-sized reactor that can power a city instead of something that can only replace a diesel generator.

▲ godelski 2 days ago | parent [-]

I think you're missing some use cases and some parameters.

For the average home, this doesn't make sense. But for a hospital? A data center? There are plenty of places that are happy to pay a premium for an independent, redundant, and/or emergency power source. Somewhere like a hospital is going to get big advantages from something like this because it not only provides electricity but hot water (reducing the electrical demand that would go to hot water creation).

There are also big advantages to remote places. Getting power in Alaska[0]. It's even difficult to get it in places like Alberta or Montana, both of which will also would take advantage of the heat source.

Even at 5 years, this is more reliable than something like a gas generator and has a lot of logistical advantages. This says it does 1MW or electric power and 1.9MW of thermal. I found a 1MW generator[1], and it looks to consume between 77-87 gal/hr. A gallon weighs 7lbs, so 80 gal is 560lbs and takes 0.3m3. At one day's consumption (1920 gal) you need to be able to store over 13klbs and it'll take up 7.3m3 (not including the volume of the container and that it needs to be stored somewhere that is dry but also well ventilated). On top of that, diesel has a self life of 6mo (can extend to a year), so you're going to be doing a lot of deliveries...

Given that, I can see a lot of places that would gladly make those trade-offs.

Also, if it can fit self-contained in a container, the parts are going to be much smaller. You gotta start somewhere, right? Doesn't seem a bad idea to start with edge customers who are willing to pay a premium.

[0] https://app.electricitymaps.com/zone/US-AK/72h/hourly

[1] https://mart.cummins.com/imagelibrary/data/assetfiles/007036...

▲ AnthonyMouse a day ago | parent [-]

> But for a hospital? A data center? There are plenty of places that are happy to pay a premium for an independent, redundant, and/or emergency power source.

Those places are just going to keep a diesel generator, because they only need it once or twice a year and it costs less.

> Somewhere like a hospital is going to get big advantages from something like this because it not only provides electricity but hot water (reducing the electrical demand that would go to hot water creation).

Diesel generators can do the same thing. Meanwhile on ordinary days the power would be supplied from the grid, which is even cheaper than diesel generators.

> There are also big advantages to remote places. Getting power in Alaska

But how many people need a MW of continuous power in the wilderness and are willing to pay that much for it?

The major industry in those areas is oil and gas.

> I found a 1MW generator[1], and it looks to consume between 77-87 gal/hr.

Diesel generators are typically used for emergency power and then the fuel consumption isn't a major concern because they're infrequently used.

Power plants for continuous stationary use will typically use the same generation methods as the grid and can then attach to natural gas pipelines or use generation methods like wind/solar/hydro that don't consume fuel.

For transient use you'd need to move fuel, but in the alternative you have to move the reactor.

> Doesn't seem a bad idea to start with edge customers who are willing to pay a premium.

Sure, but who actually are they? What usage needs a MW of continuous power but has to be in a place that can't connect to the grid? Remote mining operations maybe? But their equipment is designed to run directly on liquid fuels because electricity is assumed to be unavailable.

It's not impossible that it exists but it doesn't seem like a huge market.

	▲	godelski 20 hours ago \| parent [-]
		Sure, maybe a hospital is not the best example, but it's just serving as a way to see how it is useful. Was just a stand in for something relatable where it was understood how much someone would be willing to pay for a backup. But I'll get to better examples in a second. `> Diesel generators are typically used for emergency power` Yes, but you aren't comparing the cost of storing and delivering diesel. Yes, grid power will be cheaper but is that difference than the costs of storing, transporting, and the need to constantly check? Is it cheaper than the handover time? The time lost when electricity is down. Can you smoothly hand over generation? Is it cheaper than the cost of the gas having spoiled? These mistakes happen and they can be quite costly when it does. `> but it doesn't seem like a huge market.` It definitely is not a huge market. That's why there's a premium. But there are people that need and will pay for it. I'm also willing to bet you're significantly underestimating how many remote locations there are. Let's test ourselves. (I got the answer wrong btw and I'm willing to bet most people do.) How many research stations are there in Antarctica? Make a guess first. Here's the answer and a link[0]. And here's for the Arctic[1] (there's more!). These don't even include secret sites! Hell, I'm sure there's even a few towns in Norway[2,3] and Alaska[4], or elsewhere[5] that would be lifetime customers. 1MW isn't close to enough power to supply some of those cities but I would be surprised if they didn't want a highly reliable 1MW source of power and 2MW of heat and weren't willing to pay a high price for it. That energy goes a long way in emergencies. You're right that many of these locations have oil and gas as major industries but you are not considering two factors. 1) That still needs to be processed. You can't use oil or gas in their raw form (okay, sometimes gas but it still may contain contaminants that need to be separated). 2) You're eating your own supply. It's a lot easier to just export everything than to portion everything out. This is especially true when the product expires. If you don't rely on your own export then you never have to make the choice between "do I have enough for myself" when the product is in high demand elsewhere. Things like this have extremely high demand for military sites. They'll pay way more to not have to have constant deliveries. We're not even just talking places like nuclear launch sites. There's hundreds of remote listening locations. There's plenty of places that you add one of these to and they could run completely automated. If we're talking about a really remote location (there are quite a lot of these) then which is cheaper? Once every 5 years helicopter delivery or a constant delivery every 6 mo by truck? That first option could be a lot cheaper. You don't even need to even make a road! Certainly one of these options is much faster. Again, you're right, in that this isn't a technology we're going to see everywhere (especially at a high price point). But that's a very different thing than "there's no point in building this". I'm just trying to answer the latter question because that's what you put into question. I'm still willing to bet there's a bigger market for this kind of stuff than you would think. And to be clear, I don't think you're dumb or unimaginative or anything. I see you around here a lot, so I know you're smart. I just think with something like this it's a "everything is an edge case" type of situation, where it is very hard to actually get a good picture. First order approximations won't get you anywhere near the right answer. They're really hard to guesstimate without some expertise. I only know some surface level because I did some work with nuclear tech and we had to find applications. But what I know is that there's a lot of situations I'm not even aware of because even though they are edge cases we're talking about edge cases on the scale of billions. Even serving just 0.00001% of that is probably more than enough to warrant a product like this and make a profit. [0] Wiki lists 44 permanently active stations and and 45 summer only ones. There's a map below the listing. I was at least 50% off on my estimate. I thought at most there would be 2 dozen. https://en.wikipedia.org/wiki/Research_stations_in_Antarctic... [1] There's 57 active stations. https://en.wikipedia.org/wiki/List_of_research_stations_in_t... [2] https://en.wikipedia.org/wiki/Hammerfest_(town) [3] https://en.wikipedia.org/wiki/Honningsv%C3%A5g [4] https://en.wikipedia.org/wiki/Utqiagvik,_Alaska [5] https://en.wikipedia.org/wiki/List_of_northernmost_settlemen...

▲ ViewTrick1002 2 days ago | parent | prev | next [-]

I have a hard time seeing how communities that have trouble keeping the skills necessary to operate diesel generators will be able to switch to nuclear reactors.

https://www.spitsbergen-svalbard.com/2024/04/09/longyearbyen...

▲ ortusdux 3 days ago | parent | prev [-]

> I hope they can find a way to bring fuel costs way down.

I've spoke with some researchers and investors working on seawater uranium extraction and left quite optimistic.

	▲	philipkglass 3 days ago \| parent [-]
		Extracting uranium from seawater gives you natural uranium, which needs to be enriched for use in most power reactors. The reactor under discussion here needs higher uranium enrichment and more expensive fuel fabrication operations than common power reactors. Developing uranium extraction from seawater is a good long-term insurance plan for uranium availability, but it's not going to help this reactor get its fuel costs down.