I'm skeptical, not because it can't be achieved, but because it's not that practical.
Diesel generators are "great" because diesel doesn't evaporate. You can have it there for years, and with good design, it just springs up the next day.
This nuclear reactor has to be connected for fleet monitoring if you want to operate it. Which excludes it from many real life scenarios where diesel generators are used.
Maybe for remote locations where constant power is needed (Antarctica and such), but I see their uses being very limited.
> This nuclear reactor has to be connected for fleet monitoring if you want to operate it. Which excludes it from many real life scenarios where diesel generators are used.
I don't understand this sentence, why does connection to fleet monitoring preclude using this microreactor as opposed to a diesel generator? Can't you just hook a starlink up to it, and program it to shut down in the event of prolonged comms loss?
Meet EMD DDA40X [1], the most powerful diesel–electric locomotive model ever built on a single frame incorporating two diesel engines with an effective power output of 4920 kW. Given the expected losses in the diesel engines (~40-45% effective, 60-55% waste mostly in the form of heat) and diesel-electric traction system (power generation, traction motors, gearing etc, around 80% effective) which gives a total system efficiency of around 35%. Assuming most of the waste energy ends up as waste heat this ~30m long locomotive (a bit more than two 40ft containers) needs to shed around 9 MW of waste heat or about 4 MW per 40ft standard container length.
Am I right that 1MW of solar generation would only take about a football field worth of panels? Of course that doesn't account for battery or other storage for nighttime, etc. but seems like it would be far cheaper and far less regulatory issues unless you really needed that much power generation in a very small footprint.
“Only” a football field is a lot of space. A 1MW diesel genset on a trailer is about 30’ long by 8’ wide by 10’ tall, which is 0.4% of a football field.
Everything I've heard is that micro-reactors produce far worse waste situations than larger scale options.
I think there's a huge opportunity for nuclear power in the world today.
But: all these micro-reactor strike me as disastrously bad idea, that's all too likely to offload incredibly complex nasty gross problem to the future. Costs that alas will likely be handled as network externalities, as drains and damage against humanity and people and government, that the creators and purchasers of these device will skate through with comparatively little injury.
Looks basically like the TRIGA reactor design (without the water shielding). Seems to have similar challenges with rapid load changes. At one time I thought NASA was looking at something like this tied together with a battery pack that would allow for rapid changes in dynamic load without a lot of stress on powering up/down the reactor. And now I can't find it. Sigh.
If you're a billionaire building your bunker this would be the ultimate off-grid power source :-).
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.
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.
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.
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.
I'm sure there's a few catches or weed already have them back ordered globally but frankly anything that normalises using these self heating rocks to boil water gets my vote :)
Looks aspirational to me. 1Mw electricity at 30-100% efficiency (100??) and 1.9 Mw heat via air in the volume of a shipping container? That's moving a lot of air. And I'd want fail safe, passive control "rods" (what happens if the helium leaks out and the heat isn't being removed) before I'd sleep easy with one in my back yard.
Could this be associated to a supposed recent State Department approval?
“I just approved a program to deploy small modular nuclear reactors built in the United States to an allied country to help with their sort of energy infrastructure.”
“Which allied country would that be?”
“I can't tell you. It's not public yet.”
From Interesting Times with Ross Douthat: The DOGE Alum Asking if Foreign Aid Is America’s Problem, Jul 31, 2025
I'm not filled with optimism about this concept. Let's work backwards from crash safety (say a reactor on a truck getting t-boned by a freight train). The radioactive material needs to be held in an armored containment to avoid release. That would have to be roughly comparable to CASTOR containers in terms of its resilience. But these containers have limited capability of passive thermal energy dissipation (Google finds models that handle 10kW to 45kW thermal power generated in the interior). This would be approximately the ceiling for the direct thermal power output that is still reduced by limited efficiency of heat-to-power conversion.
This is admittedly napkin math, but it should be good enough to set expectations.
> 3. Is it really safe to fly around with in an airplane? Can major airlines help distribute these via standard flight routes to reduce cost?
These are too big for your standard air freight network or aircraft (that is, it's significantly larger then any typical ULD [Unit Load Device, shipping containers for airplanes]).
So it'll definitely be a charter to get one delivered. Weights going to be the big determinant in cost, dimensionally it looks like you could get it into anything bigger then a C-130. I doubt you'll be within the C-130s weight limits though.
I would imagine refuelings are limited because at some point you are going to need to inspect and potentially replace some of the critical components that have been exposed to hard radiation. Materials that we would think of as stable can degrade in such high radiation environments. Like a large chunk of steel can have its crystal structure disrupted as atoms get displaced by high energy neutron strikes or other fission fragments, changing its material properties and making it weaker or in most cases more brittle. Localized impurities can also be formed by either alloying elements in the metal being displaced the same way, or from transmutation of atoms into other elements from the strong radiation. And along with disrupting the material strength those impurities can cause hot spots in the metal causing more stresses and fatigue and further reducing it's lifespan.
We are actually pretty good at making alloys and materials today that can resist radiation problems better and more predictably these days, but there is still a bit of randomness from manufacturing variables that means you need a pretty large safety margin to prevent problems. They probably would work for a dozen refuelings, but the consequences of a reactor breech are too high to not have a massive safety margin. And maybe after they ran these for a few refuelings and inspected enough of them they could bump up the refueling limit before inspection or replacement a little.
The USSR did it first! No, really. There was a mobile power plant: Pamir-630D ( https://imgur.com/a/rCexHAA ).
It was even deployed to provide power to a remote Arctic outpost. It had to use an exotic coolant (basically, a rocket oxidizer) to make it work, and it had to be placed far away from anything else. The shielding was not enough to bring down the gamma radiation to a safe level when the reactor was active.
Not sure about who was first but McMurdo station in Antarctica was for a time powered by a nuclear reactor almost identical in power to the one being discussed here: http://large.stanford.edu/courses/2014/ph241/reid2/
Neat, I never heard of that! Im surprised there isn't even an english wiki page for it, I had to translate russian wikipedia and even that was a bit limited in information to satisfy my curiosity so ill have to look at other sources.
>We have fully modeled worst-case - as well as lesser-case - scenarios for an accident or leak. The analysis has shown zero impact experienced by the public.
Not a bad idea. But what if we scaled it up, say to 1.0GW. It wouldn't be portable, but it would sure be useful. So of course we instead take the fuel to the reactor. We could even call it a nuclear plant, because it doesn't move. Can we do that instead?
Here's a related company, Ultra Safe Nuclear, making TRISO fuel units.[1]
They went bankrupt in April 2025.[2] They at least got as far as making fuel units, although I suspect the video shows dummies being made, because they are not taking enough precautions for handling enriched uranium.
40 comments
[ 3.9 ms ] story [ 61.8 ms ] threadHope it is true though.
Diesel generators are "great" because diesel doesn't evaporate. You can have it there for years, and with good design, it just springs up the next day.
This nuclear reactor has to be connected for fleet monitoring if you want to operate it. Which excludes it from many real life scenarios where diesel generators are used.
Maybe for remote locations where constant power is needed (Antarctica and such), but I see their uses being very limited.
I don't understand this sentence, why does connection to fleet monitoring preclude using this microreactor as opposed to a diesel generator? Can't you just hook a starlink up to it, and program it to shut down in the event of prolonged comms loss?
But it being a 1.9mw(thermal) makes sense.
I wonder what the support requirements are, like how do you yeet the heat to make it efficient?
Also containing super heated helium seems hard for any length of time. I wonder what the operating lifespan is.
[1] https://en.wikipedia.org/wiki/EMD_DDA40X
I think there's a huge opportunity for nuclear power in the world today.
But: all these micro-reactor strike me as disastrously bad idea, that's all too likely to offload incredibly complex nasty gross problem to the future. Costs that alas will likely be handled as network externalities, as drains and damage against humanity and people and government, that the creators and purchasers of these device will skate through with comparatively little injury.
If you're a billionaire building your bunker this would be the ultimate off-grid power source :-).
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.
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...
https://www.spitsbergen-svalbard.com/2024/04/09/longyearbyen...
I'm sure there's a few catches or weed already have them back ordered globally but frankly anything that normalises using these self heating rocks to boil water gets my vote :)
“I just approved a program to deploy small modular nuclear reactors built in the United States to an allied country to help with their sort of energy infrastructure.”
“Which allied country would that be?”
“I can't tell you. It's not public yet.”
From Interesting Times with Ross Douthat: The DOGE Alum Asking if Foreign Aid Is America’s Problem, Jul 31, 2025
This is admittedly napkin math, but it should be good enough to set expectations.
2. Why only refuelable 4 times?
3. Is it really safe to fly around with in an airplane? Can major airlines help distribute these via standard flight routes to reduce cost?
4. What happens when home base monitoring detects a problem with the reactor? (And why isn't this covered in the slides to put the audience at ease?)
These are too big for your standard air freight network or aircraft (that is, it's significantly larger then any typical ULD [Unit Load Device, shipping containers for airplanes]).
So it'll definitely be a charter to get one delivered. Weights going to be the big determinant in cost, dimensionally it looks like you could get it into anything bigger then a C-130. I doubt you'll be within the C-130s weight limits though.
We are actually pretty good at making alloys and materials today that can resist radiation problems better and more predictably these days, but there is still a bit of randomness from manufacturing variables that means you need a pretty large safety margin to prevent problems. They probably would work for a dozen refuelings, but the consequences of a reactor breech are too high to not have a massive safety margin. And maybe after they ran these for a few refuelings and inspected enough of them they could bump up the refueling limit before inspection or replacement a little.
It was even deployed to provide power to a remote Arctic outpost. It had to use an exotic coolant (basically, a rocket oxidizer) to make it work, and it had to be placed far away from anything else. The shielding was not enough to bring down the gamma radiation to a safe level when the reactor was active.
Well that's a relief.
Jokes aside, very cool tech.
[1] https://www.youtube.com/watch?v=uR7VDqUbaCg
[2] https://nuclear-news.net/2025/04/04/update-on-the-bankruptcy...