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 · 7h ago
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.
acidburnNSA · 7h ago
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 · 6h ago
In order for this to happen, making websites and mobile apps is going to have to get a lot less lucrative.
AnthonyMouse · 5h ago
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.
ortusdux · 6h ago
> 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 · 6h ago
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.
cyberax · 6h ago
> 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?
acidburnNSA · 6h ago
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.
Atotalnoob · 2h ago
Could you reduce the amount of concrete by increasing the amount of tungsten?
acidburnNSA · 2h ago
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.
credit_guy · 2h ago
Pro tip: if you want to check if a nuclear reactor design is vaporware or has real legs, you check their application with the NRC (nuclear regulatory commission). It turns out that the NRC does have a page for Kaleidos [1]. You can even go and see what documents Kaleidos submitted this month. They submitted a request to be exempted from some regulation called "10 CFR 55", which they feel is not applicable to them. I have no clue if that is the case or not, but at least they seem to be in fairly frequent contact with the NRC, and that's good news.
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.
generalizations · 7h ago
"Only"
Looks like a giant part of the value is that it can be shipped in, dropped on the ground on site, turned on overnight, and it only takes up the footprint of a shipping container.
If you have 24 hrs to find an empty football field within a powercable's distance of what you're trying to power, and then fill it with solar panels and batteries, you're gonna have a bad day.
nehal3m · 6h ago
If you ship in a stack of panels, inverters and cables, sure. But maybe you could be a little smarter about it, like a container with all the electronics (inverters, batteries, management) and a bunch of folded, pre-cabled panels that you can pull out across a field. If you bring a couple of those covering a field in a few hours shouldn't be that hard and could be ready for use instantly provided the batteries are charged at delivery.
generalizations · 5h ago
You also have to make sure there's an empty football field onsite. That's a much harder ask than dropping a shipping container in a couple of parking spots.
Not sure if you’re serious. Is this something you’re proposing be used in an urban environment?
Using a bomb to flatten the nearby trees/debris/buildings/people to make way for solar panels strikes me as not preferable to a clean standalone box providing a MW of power for 5 years at a time.
Also the environment would thank you for choosing nuclear over this.
yongjik · 3h ago
I'm pretty sure GP is joking ...
djfobbz · 5h ago
Are you're seriously comparing a few containers of fold-out solar panels and batteries to a portable nuclear reactor?
Let's do the math: To match even a 1MW reactor, you'd need 2,000+ panels, inverters, batteries, mounting, and approx. 120-150 man-days of labor...and that's with pre-cabled gear. You're still looking at 8+ containers, a full crew, and a full 10-14 days to deploy, not "a few hours."
A nuclear microreactor doesn't need 54,000sqft of land or weather-dependent storage. Nice idea for a solar camp but not a replacement for a compact nuclear source.
hinkley · 3h ago
Let’s not pretend to be offended that someone else is making up an unfair scenario, as if you guys didn’t already make one up.
Nobody’s dropping off a nuclear fucking reactor in the middle of a disaster area on six hours’ notice in any universe other than the bizarro one invented by their PR firm.
You’re maybe running water desalination for an island that has known for years they want an alternative to shipping in diesel, or you’re shipping diesel generators to a disaster area because the Red Cross has a stack of them in a warehouse ready to go.
Or you’re some hyperscaler data center hoping to not have to maintain fifteen generators onsite for you eight server rooms (8 + 4 + 2 + 1 = 15), and those could potentially be replaced with battery systems or gas turbines. And again, on six months or more of notice.
If someone had an easy non-snake-oil nuclear solution we would be using it already. A realistic person would assume incremental improvements in portable nuclear over the next twenty years, not an overnight success.
supportengineer · 5h ago
What if robots/drones/automation was doing the deployment?
generalizations · 4h ago
You’ll need some peacekeeper drones, too - gotta keep the people from coming back after you evict them to make space for the solar panel fields!
denkmoon · 4h ago
the sun doesn't shine at the poles 6 months of the year. it usually doesn't shine underground or deep underwater. etc.
In places solar panels make sense they would certainly be used, but that's not everywhere.
supportengineer · 5h ago
I can imagine a Falcon 9 dropping off an automated package that unrolls/inflates the solar panels. Security would be provided by even more drones.
generalizations · 4h ago
Still need a place to unroll them. Unless you have a football field of empty space in that falcon 9, too.
esseph · 7h ago
You're not accounting for location at all.
Nor is that generating electricity at night.
Plus battery storage.
And it's closer to 4-6x football fields if you did it in say, San Francisco. 4-5x football fields in Kansas City. 6-8x football fields in Chicago. Again, plus battery storage.
hinkley · 6h ago
How many power problems would be covered by making a battery the size of this device
actinium226 · 5h ago
Depends entirely on how you charge the battery.
esseph · 6h ago
zero
hinkley · 3h ago
That’s the sort of bullshit answer you take to Reddit, not HN.
esseph · 1h ago
Name the problems a battery half the size of a flatbed trailer "solves"?
daemonologist · 7h ago
It depends on where you're at, but for a sunny place yes; somewhere like London a panel can harvest ~100 W/m^2 (0.5 MW for a football field with 100% panel coverage) averaged over the whole year, while in Arizona it's more like 230 W/m^2 (1.2 MW for a football field). NREL has some great insolation maps here: https://www.nrel.gov/gis/solar-resource-maps
For a permanent installation I would agree that solar would usually make more sense, but the mini reactor might be better in scenarios where it's replacing a diesel generator - emergencies, temporary events, confined spaces, etc.
asdfman123 · 7h ago
It requires space, setup time, and then there's the intermittency issues. You'd need enough batteries to store, what, 12 MWh? 20? More if you're accounting for cloudy days?
People just want a compact solution to generate power, not a whole separate project.
jonplackett · 7h ago
Wouldn’t the point be that it works at night too?
trklausss · 7h ago
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.
p1mrx · 7h ago
If I Google "diesel shelf life", the most common answer is 12 months. Do you have a better source? Propane probably makes more sense for fuel that needs to sit around for years.
Do you know the shelf life of TRISO fuel? I imagine it doesn't matter because it would be very expensive to build a reactor and not switch it on.
SR2Z · 7h ago
Diesel will degrade with exposure to oxygen, but a diesel engine can burn pretty much any flammable liquid that you can meter out. It really comes down to the engine itself and if it can handle less-than-perfect fuel.
whatever1 · 7h ago
It can even burn its own lubricant oil and die in a screaming runaway fashion!
rob_c · 7h ago
I'm sure a nuclear reactor can manage that too if it's a competition :p
whatever1 · 6h ago
Not sure it will sound as nice though. In fact I don't think I have heard the sound of a runaway nuclear reactor. Maybe due to the turbines it can sound exciting?
lb1lf · 6h ago
Anecdotally, I came across a large (for a single user) quantity of diesel 9 years ago. (Nothing exotic - a company went titsup and I was the only one both bidding for and capable of removing the diesel from their premises within an acceptable time frame; I got approx 80% off the pump price at the time.)
I still run my tractor and Land Cruiser off the stuff; the tractor had an outing today. Granted, neither of those engines are very particular about the fuel they are given, but still...
(Water drained off every few months, also a biocide is added to keep the diesel gunk at bay.)
AngryData · 3h ago
I mean if you trying to run that fuel in a performance application where you are pushing the fuel to its absolute limit, it might be bad, but most diesel engines can be run on nearly any burnable oil, you just get less power out and a bit dirtier burn.
They give similar specs ideals about gasoline fuel going bad in 3-6 months, and yet 95% of gasoline engines will still run 2 year old fuel fine because they aren't pushing compression ratios to the absolute possible limit, and half of the performance engines that do push limits these days have adaptable computer controlled compression and sensors which will figure out how much it can push the fuel.
If I put 5 year old diesel fuel into any regular diesel motor or generator or vehicle and it didn't start up, I would be extremely surprised, and be most worried that the fuel either wasn't diesel fuel to start with or had a wide open hole in the container that a bunch of rain water drained down into.
That said, if I had some kind of tuned up diesel motor that I was trying to push 800+ HP out of, I probably wouldn't use year old diesel fuel just in case. High performance motors like that are already straddling the line between working great and catastrophic failure and using old potentially bad fuel only adds to it.
actinium226 · 5h ago
> 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?
rich_sasha · 7h ago
I don't have any first hand experience with diesel generators, but I saw three cases where power was lost and diesel backup was switched on. In two of these three cases, the generator failed (once didn't start, the other time it ran for 30 mins). In both cases it was in scenarios where I'd imagine reasonable care and maintenance were applied.
cyberax · 7h ago
> Diesel generators are "great" because diesel doesn't evaporate.
LOL, no. I see, you have never worked with large diesels meant for backup.
If you just leave diesel fuel alone, then over time (6-9 months) the residual water separates at the bottom of the tank. And then various microbial life springs into action, happily living off all of that free energy. While there's some dissolved oxygen, it will happily use it to oxidize the fuel. But even without oxygen, the bugs will try to live off energy produced by polymerization of unsaturated hydrocarbons.
Polymerization == gunk that clogs up your fuel filters.
So you have to periodically clean up diesel fuel by removing water and filtering the gunk out. It's called "fuel polishing". Large diesels will have fixed systems, for smaller diesels, sometimes mobile systems are used like these: https://fueltecsystems.com/equipment/pneumatic-systems-2/
mikewarot · 7h ago
At this point, I'll assume that the relevant US regulatory agencies are competent, and skip the safety issues, etc.
What does it cost?
How much power can it deliver?
So what's the equivalent $/KWh?
jgeada · 7h ago
That used to be true, not so sure my trust in our institutions is high these days. Seems a few million $ donation to the right people can make all regulations just vanish.
acidburnNSA · 7h ago
Yeah there's currently a large push to dismantle the Nuclear Regulatory Commission and give reactor regulation authorities to the states.
jabl · 6h ago
For all the faults of the NRC (real or imaginary), this still strikes me as an extremely bad idea.
dylan604 · 6h ago
That's pretty much always been the case. It's just much more flagrant and in the open now.
brink · 7h ago
> That used to be true
No, that used to be believed to be true. We're just seeing the curtain come down.
The food pyramid, the CIA's "war on drugs" in South America, the wars with Iraq, Libya.. Just to name a few. Why do we pretend like bribery and corruption is this new thing?
mrtesthah · 7h ago
That sounds like an excuse to abide the open corruption that's occurring under the right-wing regime in the US today.
brink · 7h ago
No it's not. I'm replying to the guy that said "That used to be true", because it's obviously not true.
rob_c · 7h ago
And that comment is overly-fastidious.
Animats · 3h ago
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.
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.
jillesvangurp · 6h ago
You are thinking accidents. I think we need to be thinking deliberate attempts to compromise these things and all the security measures needed to mitigate against that. And most importantly, the cost associated with that. Which comes on top of already significant cost.
The naive notion of we'll just ship these all over the place by the thousands and it's going to be fine is not going to withstand a lot of critical thinking very long.
gmueckl · 6h ago
I was indeed not thinking about deliberate attacks. But that doesn't change the result much as I assume that the CASTOR containers that I used as reference are designed to withstand all of these worst case scenarios.
conorcleary · 5h ago
Unfortunately, this chain of messages underscores the importance of keeping humans in check with eachother, and the machine.
altcognito · 6h ago
Hundreds of thousands if we're talking about meeting growing demand. Which doesn't give me a lot of hope for solar either though.
ranie93 · 6h ago
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
linuxguy2 · 7h ago
How much does it cost? Would love to buy one with the HOA and run our own micro-grid while exporting electricity to the local utility.
bostonwalker · 3h ago
Not in my back yard!!
unglaublich · 7h ago
When HOA gets too powerful.
salynchnew · 7h ago
When the DOE comes after your HOA.
dylan604 · 7h ago
meh, most HOAs can take on the DOD
GuinansEyebrows · 5h ago
This is bringing “My HOA went nuclear on me!” to a whole nother level.
KaiserPro · 7h ago
From the headline I was assuming it was a tiny 20kw job.
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.
t0mas88 · 7h ago
They say it needs to be refueled after 5 years and that it can be done 4 times for a total lifespan of 20 years.
Reason077 · 7h ago
1.9 MWt still seems like a huge amount of energy/heat for something that fits on a truck and is supposedly air-cooled (they claim no water is required).
Where does all that heat go?! They must have some very impressive fans.
tralarpa · 7h ago
Yes, that's crazy. They say up to 1 MW electric which would mean (33% efficiency) 2 MW of heat to get rid of with air cooling. Later they mention facility heating which sounds more realistic, I guess?
KaiserPro · 6h ago
I mean its not that much different from a diesel generator, they are around 30% efficient, so they'd also be kicking out the same amount of heat?
but then the heat profile is different I suppose, and the efficiency doesn't depend on being able to shed heat.
colechristensen · 1h ago
Heat transfer has the lovely property of scaling nonlinearly by temperature difference. You need a lot of big fans to cool your CPU from 75C on the die to a 25C room, instead of a 50C difference these reactors will dump heat at hundreds of degrees C warmer than the local environment.
hagbard_c · 5h ago
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.
A startup where most of the money were spent on that animation on the website.
dylan604 · 7h ago
You'd be surprised at what the CAD software can do now in 3D renders. You have to design the thing in CAD anyways, so it's not like the 3D team had to model it from scratch. You could probably just do this with a request on Fivr. These aren't your parents 3D prices any more
jauntywundrkind · 7h ago
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.
yongjik · 7h ago
Considering that fossil fuels "solve" the problem by literally dumping its waste onto the atmosphere, endangering the global ecosystem, and we're still merrily using them...
I think it's a bit melodramatic to say microreactors offload nasty environmental problem to the future. Also, their environmental problem is literally at the scale of "Drop them in an abandoned mine somewhere, where they cause zero harm to the world, and we will have a few centuries to figure it out."
legulere · 6h ago
Recapturing the CO2 from the environment of fossil fuels is almost impossible is almost impossible. Recapturing radionuclides is much much more difficult. Also the duration in which radionuclides are a problem has to be taken into consideration, making even babysitting nuclear waste extremely expensive.
generalizations · 7h ago
Counterpoint: we've been powering ships with microreactors for decades.
jauntywundrkind · 7h ago
And we're starting to have to decomission them! At absurd costs!
It require enormous care & effort. It's fantastically costly. Do I think it was worth it? For a mission like this: I think yes. For the good of a nation. And a Nation that hopes to still be around to take care of the problem, the complex decomissioning decades latter. But I have so little faith that private interests will endure and bear their own responsibility for this awesome but deeply corrupting irradiating force.
LgWoodenBadger · 4h ago
That CVN also happens to have 8 reactors in it
acidburnNSA · 7h ago
Most nuclear-powered ships have reactor powers in the 40-300 MWt range, a bit beyond the typical 10 MW limit for 'microreactors'
evan_ · 6h ago
This was new to me so I looked it up- "MWt" means Megawatts Thermal - e.g. the heat output of a reactor, which would be turned into a smaller value of MWe- Megawatts Electric
Peteragain · 6h ago
Yep. And the Russians have had pluggable nuclear power for years now.. on barges: wikipedia.org/wiki/Akademik_Lomonosov
Decommissioning no doubt will consist of scuttling them over a trench. Definitely going to wake the Kraken.
corranh · 7h ago
Hopefully this needs a smaller crew to operate than a Nimitz-class aircraft carrier.
dylan604 · 6h ago
The nukes on a carrier are a much smaller team within the carrier's full crew though. So if you extracted the guys that glow in the dark, it might be more inline
It's proof that you can build a robust and safe reactor, but like all things under triple constraints it will not be cheap.
acidburnNSA · 6h ago
Meh it's a little bit worse, because smaller reactors burn a smaller fraction of their fuel and therefore make more volume of high level waste per kWh generated.
But it's not THAT much worse. Nuclear waste is already ridiculously small in volume per kWh vs. any other fuel-burning energy technology. Right now all of the waste we've accumulated from making 20% of the country's electricity for decades fits on a football field 3 meters high (that's pellets only, if you include individual dry casks it's 135 meters). So if we make lots of small reactors that are a bit less fuel efficient we might need 2 big football fields deep underground rather than 1. Compared to all the particulate and CO₂ emissions other sources make I'm just not that worried about it. Recall that fossil kills ~6 million per year from particulate emissions alone. Commercial nuclear waste has never hurt anyone, and is unlikely to do so in the future.
AngryData · 3h ago
Not to mention if we really wanted to and/or had enough of a supply of it, that higher grade waste can in large part be recycled and used again.
DoctorOetker · 7h ago
From a humanistic species survival perspective, we should conserve nuclear energy for interstellar travel.
9dev · 7h ago
Interstellar travel to… where? It’s like saving your money for an immortality treatment that’ll eventually hit the market. Well yes it might, someday in the far far future. Practically speaking, this money should better be invested in your health now instead, aka. preservation of the only spaceship we have right now—Earth.
DoctorOetker · 4h ago
To different star systems obviously.
Short of discovering portals or wormholes (natural or artificial), we should only assume demonstrated space propulsion technology to make the trip. With current technology its a long trip, and its cold and dark inbetween 2 stars. We should definitely conserve fissile materials until we demonstrate fusible materials for reliable power generation.
XorNot · 3h ago
If interstellar travel ever becomes possible you'd already have access to all the resources of the solar system as well as the output of the entire sun.
The scale of the problem l, technologically simply renders earthbound resource constraints irrelevant.
Like you're into "synthesize antimatter with solar power" at that point.
DoctorOetker · 2h ago
> If interstellar travel ever becomes possible you'd already have access to all the resources of the solar system as well as the output of the entire sun.
I'm not going to argue circular conditions, this is precisely why we should preserve dense energy sources, first an alternative abundant energy source must be demonstrated, before squandering it locally.
> The scale of the problem l, technologically simply renders earthbound resource constraints irrelevant.
Hidden in such statements is the implicit assumption that mining the solar system for fissile materials is less energy intensive than mining them locally.
We should make sure interstellar travel remains affordable by the time we decide to afford seeding other star systems.
Nothing prevents interstellar travel with current technology, it would just take a long time. We should keep this mode of travel, where survival on the ship is powered with known feasible technology (nuclear fission) on the table and conserve fissile materials until we succeed in compact fusion plants, in that case this constraint no longer is an argument to preserve fissile materials.
Speculating other energy storage technology like "antimatter storage as a battery to store solar power" before launching to another star is just that: speculation. We shouldn't squander fissile materials on the basis of feel-good speculation.
XorNot · 1h ago
No the assumption is that the magnitude of energy involved in interstellar travel is so large that it dwarfs all other considerations. If you can't afford to expend the energy to travel around the solar system to acquire resources, you definitely can't afford to engage in interstellar travel.
And then of course, if you can't afford the energy to sustain a human population on Earth in decent conditions, you also definitely can't afford interstellar travel. Because implicit in your assumption is that somehow the extremely limited number of people who could be put on a slow ship (and by slow we're talking thousands of actual years minimum at "current technology" levels) will somehow be able to command and control all of Earth's fissile resources.
Peteragain · 7h ago
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.
gregbot · 6h ago
This type of fuel basically cant melt so with no helium it would just heat up and natural convection would cool it.
1shooner · 6h ago
>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.
Well that's a relief.
hereme888 · 4h ago
So if the truck were electric, it could run for >5 years straight, even uphill?
Jokes aside, very cool tech.
1970-01-01 · 3h ago
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?
croes · 7h ago
If they go bankrupt who is responsible for the waste?
lawlessone · 7h ago
you are :D
yikes from their FAQ:
"The plan is for the small amount of spent fuel (the volume of the spent fuel in one reactor is equivalent in size to just two Walmart gas grill propane tanks) that comes out of our reactors at the end of their duty cycle to only be temporarily stored on-site until a federal repository or interim storage solution becomes available. "
They don't even have plan while the exist now.
acidburnNSA · 7h ago
Well no one does. The feds cancelled Yucca mountain and so there's nowhere for anyone to put nuclear waste. By law it belongs to the feds.
So everyone just leaves it in the reactor's parking lot for now, in big concrete and steel dry casks.
dylan604 · 7h ago
> equivalent in size to just two Walmart gas grill propane tanks
Is this a real measurement in tank sizes? Why not just say two 20lb tanks? What if I bought my tank from Home Depot? Are they a different size? Do they think using Walmart makes it more relatable?
lawlessone · 6h ago
>Is this a real measurement in tank sizes?
That's only 0.393% the size of a football field!
Seriously though, isn't a lump of radioactive material that size actually huge?
AngryData · 3h ago
I mean that is exactly what we do right now with all nuclear waste. Without a nuclear material repository there is only so much you can do. You don't want to just dig a simple hole somewhere and start tossing everyone's high level waste into it, that would just be asking for a massive disaster.
gigel82 · 7h ago
That's the right question to raise up.
metadat · 6h ago
1. Can I have one in my driveway?
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?)
AngryData · 3h ago
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.
MadnessASAP · 5h ago
> 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.
can16358p · 7h ago
Sounds too good to be true.
Hope it is true though.
EA-3167 · 7h ago
I have no idea if the testing will go well, if the regulatory/political environment will accept it, but as far as the company, the tech and the promise of testing?
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 :-).
acidburnNSA · 7h ago
It's a lot different from a TRIGA. It doesn't have hydrogen in the fuel and it uses high temperature/high pressure helium gas as the coolant (vs. water in a TRIGA).
We did run a nuclear reactor in space once that did use TRIGA fuel. It was called SNAP-10A. More recently, the Kilopower test ran a reactor on land but intended for space with a U-Mo metallic fuel.
daft_pink · 7h ago
When can I get a smaller one to power my AirTag?
philipkglass · 7h ago
I know that this is a joke, but reactors cannot scale down that far. Unlike an electrical source powered by radioactive decay (like certain pacemakers [1]), the minimum mass for a nuclear reactor includes several kilograms of material. It's possible to shed neutron moderator mass by using high-purity fuel operating on fast fission, but these require more fuel to go critical so they still have multi-kilogram masses.
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.
AngryData · 2h ago
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.
actinium226 · 5h ago
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/
calvinmorrison · 7h ago
I have oil clients who would love this. they have to run expensive engines left and run on site
wewtyflakes · 7h ago
The poetic irony!
ggm · 7h ago
A flame chart of energy consumption to customer from well-head typically shows an astronomical amount consumed at head in the gas train. It can be a significant sub of the total available energy consumed at the head and in pipeline and shipping, to produce the output which can be sold.
Unfortunately much of it can't be sold or shipped off site and if it isn't used, will be fugitive gas emissions or flared.
Replacing the diesel and other fuels used on-site is good. But it's only part of the story. Running the train would certainly burn a lot of gas, so replacing that would be good.
(-not a fan of SMR for a variety of reasons, mostly political)
dsadfjasdf · 6h ago
Thoughts on using stranded gas as bitcoin miners?
ggm · 6h ago
Inventing reasons to perpetuate fossil fuel extraction is counter productive.
wmf · 6h ago
It's already being done.
idontwantthis · 8h ago
Is it real?
cactacea · 7h ago
From their job listings:
> Additional Requirements
> Must be willing to work extended hours and weekends as necessary to accomplish our mission.
Yes it's real. There are a lot of good people who I know personally and a lot of funding going into this. They have a plan to get fuel and will try to turn the first one on in Idaho soonish (like next year)
kwhitefoot · 7h ago
I was hoping the FAQ would answer that but, as I expected, I was disappointed.
rob_c · 7h ago
Fantastic if true.
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 :)
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've spoke with some researchers and investors working on seawater uranium extraction and left quite optimistic.
Can it survive 20 kilos of TNT planted by a terrorist?
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.
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.
[1] https://www.nrc.gov/reactors/new-reactors/advanced/who-were-...
Looks like a giant part of the value is that it can be shipped in, dropped on the ground on site, turned on overnight, and it only takes up the footprint of a shipping container.
If you have 24 hrs to find an empty football field within a powercable's distance of what you're trying to power, and then fill it with solar panels and batteries, you're gonna have a bad day.
Using a bomb to flatten the nearby trees/debris/buildings/people to make way for solar panels strikes me as not preferable to a clean standalone box providing a MW of power for 5 years at a time.
Also the environment would thank you for choosing nuclear over this.
Let's do the math: To match even a 1MW reactor, you'd need 2,000+ panels, inverters, batteries, mounting, and approx. 120-150 man-days of labor...and that's with pre-cabled gear. You're still looking at 8+ containers, a full crew, and a full 10-14 days to deploy, not "a few hours."
A nuclear microreactor doesn't need 54,000sqft of land or weather-dependent storage. Nice idea for a solar camp but not a replacement for a compact nuclear source.
Nobody’s dropping off a nuclear fucking reactor in the middle of a disaster area on six hours’ notice in any universe other than the bizarro one invented by their PR firm.
You’re maybe running water desalination for an island that has known for years they want an alternative to shipping in diesel, or you’re shipping diesel generators to a disaster area because the Red Cross has a stack of them in a warehouse ready to go.
Or you’re some hyperscaler data center hoping to not have to maintain fifteen generators onsite for you eight server rooms (8 + 4 + 2 + 1 = 15), and those could potentially be replaced with battery systems or gas turbines. And again, on six months or more of notice.
If someone had an easy non-snake-oil nuclear solution we would be using it already. A realistic person would assume incremental improvements in portable nuclear over the next twenty years, not an overnight success.
In places solar panels make sense they would certainly be used, but that's not everywhere.
Nor is that generating electricity at night.
Plus battery storage.
And it's closer to 4-6x football fields if you did it in say, San Francisco. 4-5x football fields in Kansas City. 6-8x football fields in Chicago. Again, plus battery storage.
For a permanent installation I would agree that solar would usually make more sense, but the mini reactor might be better in scenarios where it's replacing a diesel generator - emergencies, temporary events, confined spaces, etc.
People just want a compact solution to generate power, not a whole separate project.
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.
Do you know the shelf life of TRISO fuel? I imagine it doesn't matter because it would be very expensive to build a reactor and not switch it on.
I still run my tractor and Land Cruiser off the stuff; the tractor had an outing today. Granted, neither of those engines are very particular about the fuel they are given, but still...
(Water drained off every few months, also a biocide is added to keep the diesel gunk at bay.)
They give similar specs ideals about gasoline fuel going bad in 3-6 months, and yet 95% of gasoline engines will still run 2 year old fuel fine because they aren't pushing compression ratios to the absolute possible limit, and half of the performance engines that do push limits these days have adaptable computer controlled compression and sensors which will figure out how much it can push the fuel.
If I put 5 year old diesel fuel into any regular diesel motor or generator or vehicle and it didn't start up, I would be extremely surprised, and be most worried that the fuel either wasn't diesel fuel to start with or had a wide open hole in the container that a bunch of rain water drained down into.
That said, if I had some kind of tuned up diesel motor that I was trying to push 800+ HP out of, I probably wouldn't use year old diesel fuel just in case. High performance motors like that are already straddling the line between working great and catastrophic failure and using old potentially bad fuel only adds to it.
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?
LOL, no. I see, you have never worked with large diesels meant for backup.
If you just leave diesel fuel alone, then over time (6-9 months) the residual water separates at the bottom of the tank. And then various microbial life springs into action, happily living off all of that free energy. While there's some dissolved oxygen, it will happily use it to oxidize the fuel. But even without oxygen, the bugs will try to live off energy produced by polymerization of unsaturated hydrocarbons.
Polymerization == gunk that clogs up your fuel filters.
So you have to periodically clean up diesel fuel by removing water and filtering the gunk out. It's called "fuel polishing". Large diesels will have fixed systems, for smaller diesels, sometimes mobile systems are used like these: https://fueltecsystems.com/equipment/pneumatic-systems-2/
No, that used to be believed to be true. We're just seeing the curtain come down.
The food pyramid, the CIA's "war on drugs" in South America, the wars with Iraq, Libya.. Just to name a few. Why do we pretend like bribery and corruption is this new thing?
[1] https://www.youtube.com/watch?v=uR7VDqUbaCg
[2] https://nuclear-news.net/2025/04/04/update-on-the-bankruptcy...
This is admittedly napkin math, but it should be good enough to set expectations.
The naive notion of we'll just ship these all over the place by the thousands and it's going to be fine is not going to withstand a lot of critical thinking very long.
“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
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.
Where does all that heat go?! They must have some very impressive fans.
https://www.generatorsindustrial.com/products/1mw-diesel-gen... has a simple radiator.
but then the heat profile is different I suppose, and the efficiency doesn't depend on being able to shed heat.
[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.
I think it's a bit melodramatic to say microreactors offload nasty environmental problem to the future. Also, their environmental problem is literally at the scale of "Drop them in an abandoned mine somewhere, where they cause zero harm to the world, and we will have a few centuries to figure it out."
We just awarded $0.5B to decommission the USS Enterprise (CVN 65), the first nuclear aircraft carrier. More will follow! https://theaviationist.com/2025/06/03/uss-enterprise-dismant...
The DoE has been helping to decomission Los Angeles class attack subs for a while now. Here's a piece on that: https://www.defense.gov/News/Feature-Stories/Story/Article/4...
It require enormous care & effort. It's fantastically costly. Do I think it was worth it? For a mission like this: I think yes. For the good of a nation. And a Nation that hopes to still be around to take care of the problem, the complex decomissioning decades latter. But I have so little faith that private interests will endure and bear their own responsibility for this awesome but deeply corrupting irradiating force.
And it is a money pit.
And then you have things like this: https://www.navytimes.com/news/your-navy/2019/01/10/two-sail...
It's proof that you can build a robust and safe reactor, but like all things under triple constraints it will not be cheap.
But it's not THAT much worse. Nuclear waste is already ridiculously small in volume per kWh vs. any other fuel-burning energy technology. Right now all of the waste we've accumulated from making 20% of the country's electricity for decades fits on a football field 3 meters high (that's pellets only, if you include individual dry casks it's 135 meters). So if we make lots of small reactors that are a bit less fuel efficient we might need 2 big football fields deep underground rather than 1. Compared to all the particulate and CO₂ emissions other sources make I'm just not that worried about it. Recall that fossil kills ~6 million per year from particulate emissions alone. Commercial nuclear waste has never hurt anyone, and is unlikely to do so in the future.
Short of discovering portals or wormholes (natural or artificial), we should only assume demonstrated space propulsion technology to make the trip. With current technology its a long trip, and its cold and dark inbetween 2 stars. We should definitely conserve fissile materials until we demonstrate fusible materials for reliable power generation.
The scale of the problem l, technologically simply renders earthbound resource constraints irrelevant.
Like you're into "synthesize antimatter with solar power" at that point.
I'm not going to argue circular conditions, this is precisely why we should preserve dense energy sources, first an alternative abundant energy source must be demonstrated, before squandering it locally.
> The scale of the problem l, technologically simply renders earthbound resource constraints irrelevant.
Hidden in such statements is the implicit assumption that mining the solar system for fissile materials is less energy intensive than mining them locally.
We should make sure interstellar travel remains affordable by the time we decide to afford seeding other star systems.
Nothing prevents interstellar travel with current technology, it would just take a long time. We should keep this mode of travel, where survival on the ship is powered with known feasible technology (nuclear fission) on the table and conserve fissile materials until we succeed in compact fusion plants, in that case this constraint no longer is an argument to preserve fissile materials.
Speculating other energy storage technology like "antimatter storage as a battery to store solar power" before launching to another star is just that: speculation. We shouldn't squander fissile materials on the basis of feel-good speculation.
And then of course, if you can't afford the energy to sustain a human population on Earth in decent conditions, you also definitely can't afford interstellar travel. Because implicit in your assumption is that somehow the extremely limited number of people who could be put on a slow ship (and by slow we're talking thousands of actual years minimum at "current technology" levels) will somehow be able to command and control all of Earth's fissile resources.
Well that's a relief.
Jokes aside, very cool tech.
yikes from their FAQ:
"The plan is for the small amount of spent fuel (the volume of the spent fuel in one reactor is equivalent in size to just two Walmart gas grill propane tanks) that comes out of our reactors at the end of their duty cycle to only be temporarily stored on-site until a federal repository or interim storage solution becomes available. "
They don't even have plan while the exist now.
So everyone just leaves it in the reactor's parking lot for now, in big concrete and steel dry casks.
Is this a real measurement in tank sizes? Why not just say two 20lb tanks? What if I bought my tank from Home Depot? Are they a different size? Do they think using Walmart makes it more relatable?
That's only 0.393% the size of a football field!
Seriously though, isn't a lump of radioactive material that size actually huge?
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?)
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.
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.
Hope it is true though.
That is real.
https://www.energy.gov/ne/articles/radiant-completes-study-f...
If you're a billionaire building your bunker this would be the ultimate off-grid power source :-).
We did run a nuclear reactor in space once that did use TRIGA fuel. It was called SNAP-10A. More recently, the Kilopower test ran a reactor on land but intended for space with a U-Mo metallic fuel.
[1] "Plutonium powered pacemakers (1974) https://www.orau.org/health-physics-museum/collection/miscel...
>first nuclear battery can deliver 100 microwatts of power and a voltage of 3V
>plans to produce a battery with 1 watt of power by 2025
https://www.independent.co.uk/tech/nuclear-battery-betavolt-...
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.
Unfortunately much of it can't be sold or shipped off site and if it isn't used, will be fugitive gas emissions or flared.
Replacing the diesel and other fuels used on-site is good. But it's only part of the story. Running the train would certainly burn a lot of gas, so replacing that would be good.
(-not a fan of SMR for a variety of reasons, mostly political)
> Additional Requirements
> Must be willing to work extended hours and weekends as necessary to accomplish our mission.
So... not yet.
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 :)