SMR make as much sense as space datacenters. You can gaslight investors, you can gaslight HN, you can gaslight a national parliament full of lobbyists, but you can't gaslight thermodynamics.
Are you of the opinion that the comments on that article are conclusive evidence for all SMR startups failing?
If so, how? Please try to be specific.
I don't see evidence of even one startup failing there, never mind all of them.
0 - https://world-nuclear.org/information-library/nuclear-power-...
I am not buying.
And neither is anyone else these days.
https://www.rechargenews.com/analysis/smrs-v-renewables-mini...
"What about the costs, both in terms of Capex to build them and the levelised cost of the power they produce?
Gadomski said: “We are very suspect of projections of costs from companies because they're inclined to be more favourable, as opposed to being more realistic. I think that getting a good cost estimate is something that is not possible right now because we haven't built any.”"
>I don't see evidence of even one startup failing there
"SMR developers will all want to avoid the fate of NuScale, the sector trailblazer that saw a pioneering US power deal cancelled when its estimated LCOE soared to $89/MWh from a previous $58/MWh."
Just a 100% cost mistake. Oops.
And even if they could have reached their 58$/MWh target, let's see what is the cost of competition...
https://www.pv-magazine.com/2026/05/06/firm-solar-and-storag...
"Firm wind-plus-storage costs in 2025 ranged from around $59/MWh in Inner Mongolia to $88/MWh to $94/MWh across Brazil, Germany, and Australia, with costs projected to fall to roughly $49/MWh to $75/MWh across those markets by 2030."
Oops oops.
"Construction timelines are also shortening, with projects typically built within one to two years of securing permits and grid connection."
Oops oops oops.
Renewable is running circles around nuclear. Every renewable technology is beating forecast. Every nuclear technology is breaking costs predictions and deadlines.
You do need to have unreasonable goals for things once in a while. In this case, I don't have a particularly fixed stance about SMR's, but the claim that "Thermodynamics are the reason why SMR aren't, and will never, be economical" feels a bit stronger than it is warranted. Never is a damn' looooong time. And I can easily imagine things being less efficient, but having other advantages that make them more economical. Claiming it's impossible is just stretching.
And the link between thermodynamics and the price of electricity is what?
Sure, that is economics, not thermodynamics. I don't necessarily agree with the SMR manifesto, but it is conceivable that improved financing, construction, operation and oversight could make an SMR cheaper than a larger reactor.
The fact that we haven't seen more widespread use of SMRs suggests that you're right. But it's important to point out that there are cost saving opportunities that could potentially reduce the net price per watt despite worse thermodynamic efficiency.
The additional per-site engineering required to reuse things like turbines and dynamos is almost certainly going to kill any savings it would have. If you're already shipping a building-sized reactor, what's one more turbine? Realistically the main reusable component is the grid hookup itself - but that would incentivize building a large-scale reactor on the site.
As would reusing the turbines, for that matter: you can't exactly power the turbines of a 100MW coal plant with a 10MW reactor, and shipping ten inefficient 10MW reactors to the site just so you can reuse the existing ancient turbine isn't exactly an attractive option either.
Second is that nuclear reactor efficiency tends to improve with size. The ratio of thermal watts to electric watts tends to be better with large reactors. I'm not super well versed on the engineering tradeoffs here by my rough understanding is that waste heat scales with surface area while useful energy extraction scales with volume.
The big costs are still going to be the cost of siting and building the reactor, the fuel, and the ongoing cost of running it. They pay off over a very long time horizon, so it's also the opportunity cost.
https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/n...
Russia actually does have a smallish SMR but it wasn't terribly cheap to build nor operate. IIRC it is in the form of a ship and used to power a city somewhere in the north.
SMR has a place for sure but no one has demonstrated the unit costs savings of making a lot of them yet.
You can actually get some, if not most, of the economy of scale by doing a fleet build of one specific design. The US seems to be working on that and picked the Westinghouse AP-1000. I think that initiative has a decent chance of succeeding. The first few will be slow and expensive to build (even China has had delays with their nuclear roll out) but the subsequent ones will get cheaper and faster to build. This is how some countries did it during the first nuclear power expansion era.
you are in this thread a lot, so i am guessing you must be very familiar with the industry. maybe you can help me understand:
is the wikipedia on SMRs incorrect/lying when they say that there are commercially operating SMRs since 2020?
and how have so many smart people and companies been duped into seriously considering SMR technology if SMRs apparently break the laws of thermodynamics?
And struggling, propped up by taylor-made laws and public money.
>how have so many smart people and companies been duped into seriously considering SMR technology if SMRs apparently break the laws of thermodynamics?
Never said they break the laws of thermodynamics. They are just inefficient and will never be more efficient than alternatives such as... Bigger nuclear reactors.
Or solar.
And how long have you been out there? Have you never seen investors dumping and wasting billions in dead-ends? Never seen a mania before?
Nuclear attracts clever people, but it isn't smart nor wise.
Nuclear power plants are eye watering levels of expensive. The require massive scale and cost with lengthy approvals and requirements, the fundamental idea of SMRs is to move that cost and approvals into a smaller scale so that multiple standard units can be produced and deployed in a turnkey situation, they still will be expensive but the time to deploy and cost will be significantly reduced.
We also know SMRs work very well, considering the majority of the US Navy is powered entirely with SMRs and have been for a very long time. Off the top of my head ship power has been exported to local areas for disaster relief
Solar is absolutely fantastic and your average person should not be hawking at solar for your home to offset your power bill. The problem with solar is that you need power 24/7 and solar will not make power in the night.
I don't think the likes of Westinghouse, Siemens, Rolls Royce and GE are duped. They are trying to solve a very hard problem!
Ok, question: for the cost of one nuclear power plant, how many batteries can you have?
For the cost of the R&D of one next generation nuclear reactor design, how many next generation battery and solar panels technologies can you develop?
The best energy strategies are all-of-the-above.
We could have had mass solar deployment since the 70s. We chose not to, and allocate the money elsewhere. Nuclear will take away billions in public money, put it into the hands of nuclear industries, to get electricity at twice the going rate, maybe, in twenty years. A white elephant and a waste of effort.
https://www.americanprogress.org/article/5-hidden-ways-the-g...
This is a horrible argument. Yeah, let’s not spend money improving technology. We wouldn’t have increased Solar panel efficiency if we followed such ill advice.
We didn't for decades. The photoelectric effect is known since the XIXth century. Solar panel research could have had far more money behind it since the 70s and the first oil crisis. It was a choice not to. And the current US and Swiss governments are choosing to prop up some industries -coal, nuclear- at the expense of others, with public money that don't grow on trees.
Not that many. Sizewell C the latest nuclear project in the UK is projected to cost around 50 billion and expected to last for 60 years. We can cut that estimate short to say oh well, About a billion a year for the next 50 years.
Assuming that you can purchase storage at $70/kwh with 50 billion you could purchase around 715GWh of battery storage, at the same output of Sizewell C that means you could output 3.2GW for 200+ hours! wow.
One problem. The batteries will realistically only last somewhere between 10-20 years. A moderate 15-year estimate would be more realistic. Now obviously it's very hard to calculate and account for a reduction in pricing increase in capacity etc... But with today's technology you would have to buy the pack 3.33 times over
So now you go into 0.300 * 715GWh gives you 214.5 GWh and now with that 3.2GWh load it could run for just shy of 3 days. This is like the entire capacity storage of China right now.
So yeah, to answer your question 214.5 GWh of storage
There are two ways of achieving economies of scale:
1. make things bigger
2. make more of them
Making things bigger generally is more effective when n is small. You need fewer sites, fewer approvals, each of the steps in the process is done fewer times.
When n is large, you can build and optimize a factory for them and achieve economies of scale that way.
Nuclear plants got large to take advantage of economies of scale because n is small. Nobody's building millions or even thousands of SMR's.
And what's their cost per MWh?
Considering they are fueled by highly-enriched uranium: are you okay with most of the world being handed the capability to build nukes?
>Considering they are fueled by highly-enriched uranium: are you okay with most of the world being handed the capability to build nukes?
There are SMR designs that do not use highly-enriched uranium.
https://assets.publishing.service.gov.uk/media/69b2f41497f6f...
" The RR SMR uses PWR technology and industry standard LEU fuel and builds on operational experience from existing PWR reactors."
I cite this as RR is the most advanced out of all the other companies working on this afaik
true, you said "gaslight thermodynamics", which i have no idea what that means, so i took a guess at what you were implying.
>never be more efficient than alternatives such as... Bigger nuclear reactors.
is efficiency really the only metric to be considered? i feel like available space, availability of alternatives, time to complete construction, etc. are worthwhile to consider.
>And how long have you been out there? Have you never seen investors dumping and wasting billions in dead-ends? Never seen a mania before?
considering the length of time and sheer number of people, companies, and governments worldwide considering/investing in SMR tech it seems unlikely to be a mania. but i am not an expert. you are talking like you are one, which is why i am asking questions.
All of these favor again bigger reactors.
>considering the length of time and sheer number of people, companies, and governments considering/investing in SMR tech it seems unlikely to be a mania.
All of the Swiss energy companies are asking to be bailed out in advance of the investment in nuclear.
how does having less available space favor a bigger reactor?
and how is constructing a bigger reactor faster than constructing a smaller one?
If a big nuclear reactor takes 10x more space but has 20x more capacity, then it means not having much space favors the big nuclear reactor rather than building 10 small ones that will take twice more space.
(and same for the time)
just picking random numbers:
i have 1 square mile available. a big reactor takes 4 square miles. i cannot fit a big reactor, despite the bigger reactor being more efficient.
how are these different? one is an example, one is general, but they communicate the exact same point. if you have something that requires 4 sq. miles, you cannot fit it into a place that is 1 sq. mile in size because there is not enough space to fit it.
>as they are still more compact per GWh.
i am really struggling here... if i cannot fit something large, whether the large thing is "more compact per GWh" does not matter. i only have so much physical space to work with. if its too big, its too big.
for a more easily visualized example, you cannot fit a reactor from three mile island into a submarine. efficiency doesnt come into the equation, because physical space constraints get in the way first.
Well, if you have 1000 places of 1 square mile and 0 space of 4 square miles, the available space is 1000 square miles. If you have 100 places of 4 square miles, the available space is 400 square miles.
You cannot say that the first sentence means the same thing that the second sentence, and you cannot say that "there is not enough space" is only something you can say in the first-sentence situation and not in the second-sentence situation.
Maybe what you meant to say is not "there is not enough space", but "there is plenty of small space but not a lot of large space" (which I doubt is true in the real world: space occupancy is usually regrouped in dense areas, leaving non-dense areas).
> if i cannot fit something large ... i only have so much physical space to work with
First, the idea that, for a domestic power plant, you only have limited space, seems very unrealistic. The real world is not a submarine or a 7/11: you want your power plant at the periphery of cities, not squeezed between 2 buildings in the middle. There is only disadvantage of doing so: you cannot distribute high power lines from the middle of the city safely, you probably need facilities to deal with the fuel, probably need water for cooling, probably need a security perimeter as you have around any typical factory, the cost of the square meter is more expensive, ...
But secondly, you need the power plant to produce some power. If your country needs X GWh, and you need either 1 large power plant of 4 square miles or 10 SMR of 1 square mile and you just have few places where you can put a power plant, the "the unit itself is more compact" does not matter . I only have so much physical space to work with. If the surface needed to get X GWh using SMR is too big, it's too big.
> you cannot fit a reactor from three mile island into a submarine
Yep. Similarly, you cannot fit a SMR in a bicycle. But how is that relevant? In real life, domestic power plant do not have the constraints of being in thigh places (on the opposite, it is better for a power plant to be in regions that also happen to not have thigh places).
my bad, i forgot i was on HN where this type of pedantry is the national sport. it sure sucks any tiny little bit of enjoyment one might get out of having a conversation. it's evident from the rest of your comment you knew exactly what i meant.
>First, the idea that, for a domestic power plant, you only have limited space, seems very unrealistic [...] But how is that relevant? In real life, domestic power plant do not have the constraints of being in thigh places
part of the point of SMRs is to be able to have them in space-constrained places where you otherwise cannot build a large facility. that's the appeal! google and meta aren't looking at them so they can power san fransisco or the country with multiple GW. they want to power a datacenter. i can think of other examples of space-constrained places where an SMR is appealing and a traditional facility is impossible, but you've managed to kill any interest i had in having a conversation.
Pretending that saying "we don't have much space" and crying like a baby when someone say "well you may not have plenty of 10 miles squares areas, but you can put a 4 miles square large reactor in one of them, and it will be better than having to build 10 1 miles square small reactors", that's being the pedantic one: you cannot complain that normal people understand normally what "we dn't have much space" means.
> part of the point of SMRs is to be able to have them in space-constrained places
Yes, but this is not a problem that exists in real life. It helps in some scenarios, but it is not the main practical issues that people have.
> that's the appeal! google and meta aren't looking at them
Google and Meta are not looking at SMR _because they don't have enough space_. This is not true at all: if you look at their projects, they have plenty of space.
They are looking at them because they want to generate a small quantity of electricity for their own usage. They want their own small reactor. But it does not invalidate that these small reactors are less efficient than big reactors: they are just happy to pay 2X dollars for a reactor they fully own than to pay X dollars for the same quantity of energy for a share of a big reactor, because it is more difficult to manage if you have to find partners and make sure everyone is agreeing.
As for speed, a 100 MW reactor is not commissioned in 1/5 of the time a 500 MW reactor is.
I don’t think it’s going to work out that way, but that’s how it’s being sold.
But, yes, I get it is how it is sold. Just that even sold like that, people with common sense should say "wait a minute, that's obviously not that simple".
For small quantities, the former is usually more effective -- making things bigger lets you make fewer of them, reducing costs.
For large quantities, a factory can enable insane economies of scale.
SMR proponents are talking about building dozens of reactors. That fits very firmly in the "small quantity" column where economies of scale almost always favor building things bigger.
Yes, we have hydro.
Wind is way too unpredictable, solar is too.
So, we can only have 2 powers to provide base load in Sweden.
The aforementioned subsidies aren't just for the electricity it produces, it is also for the electricity it could produce. The nuclear plant has a right to sell electricity to the grid at a certain price. Market price too low? The government pays the difference. No demand? The government buys the unused production capacity.
In practice this means that during periods of excess you are shutting down dirt-cheap solar and wind just so you can run a heavily-subsidized nuclear power plant. Nuclear doesn't pick up the gaps left by solar and wind, solar and wind pick up the gaps left by nuclear!
Now what?
haha cant even reply to tghe below thanks
"Nuclear base load is a lie."
okay turn it off then bibba
Nobody in the thread has proposed turning off all nuclear, hence you were building a straw man. Please don’t do that on HN.
That's why the government has to indemnify the companies against those risks.
Spot market prices are not total system costs.
Finland just built a spent-fuel repository for ~ € 1 billion. For the entire country. Just the single EPR at Olkiluoto 3 will produce electricity worth €100 billion over its lifetime if you assume a price of 10 cents/kWh.
So at 10 cents, it would be 1% of the price of electricity if Olkiluoto 3 had to finance the whole thing by itself.
Therefore, even assuming for a second your counterfactual that nuclear power isn't cost-competitive, it wouldn't be due to the disposal costs.
Of course it's also not true that nuclear isn't cost competitive. It absolutely is.
Regarding cost competitiveness: if new nuclear is cost competitive in Sweden, how come it needs to be so heavily subsidized?
2. Nuclear is not heavily subsidized. In fact, it is intermittent renewables that are and must be heavily subsidized pretty much everywhere. In Germany, for example, just the EEG is more than €20 billion per year. And that's not the only subsidy by far.
Within these non-competitive markets that feature heavily subsidized intermittent renewables, other sources may need guarantees, though last I checked the biggest guarantee in Sweden is the one protecting from the risks of government action.
Which is the biggest risk for nuclear projects.
The Swedish authorities are right now processing requests for subsidies from prospective owners of future nuclear plants. You can read their announcements here for instance. See the little summary fact box at the bottom. https://www.regeringen.se/pressmeddelanden/2026/06/ansokan-o...
So a whole lot of sense given the entire US Navy uses them and I already have one datacenter operating up in space (small test unit that over 3 months has provided ZERO issues) and a bigger one heading up into orbit next year when it's done being made.
"but you can't gaslight thermodynamics"
No but you can certainly conflate them like you're doing right now.
Hyperspectral satellite imagery - think ASTER/LANDSAT/MODIS but more modern, for surficial minerals study.
"How did you get it up?"
How else? Paid a rocket company to launch it into orbit after proving various flightworthiness tests and getting various certifications and permissions from relevant gov't authorities.
"How does one usually talk with their satellite. I guess you don't merely have a dish since it's probably not geostationary."
K-band. Don't need tons of power, just a good LoS from ground on your target. And yea, not Geostat, I'm in LEO.
100kw is literally nothing to generate in space. At typical silicon efficiencies that's football field in size, and about 70% that if you jump to more expensive multi-junction cells. I can make a folding panel the size of a compact car that'd unfurl out to cover that. That's maybe 4 hours in NX just retooling my current design. The only limitation is the capabilities of the launch vehicle.
I've already got one small (single 4U) datacenter in orbit. It works. It works GREAT. It can scale up to constellation quantity.
And I don't have to waste any water for cooling or constantly pollute the air for power generation or throw extra waste heat into our atmosphere, as a side bonus.
It makes plenty of sense to those with the education. What's hilarious is I'm doing all this on a GED.
Is the business of the US Navy to sell electrity on the market?
You are the one conflating things that have absolutely no connections.
No but they do use those reactors to power areas in times of disaster relief.
Land-based deployments don't have this constraint.
And of course, all non-naval reactors are naturally going to be larger: they aren't surrounded by a practically-infinite fluid heatsink.