Smaller reactors bring nuclear power closer to fulfilling its promise • Hacker News Board

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#51

Post by bryanlarsen » Fri, Aug 28, 2026, 2:25 PM UTC

mayama wrote: post #41

hwillis wrote: post #14

And a contrasting article from IEEE: https://spectrum.ieee.org/the-forgotten-history-of-small-nuc... > Samuel B. Morris, the general manager and chief engineer of Los Angeles’s Department of Water and Power, traveled all the way to Geneva in 1955 to attend the first International Conference on the Peaceful Uses of Atomic Energy. There, he made a case for small reactors, arguing that because the “number of small units…

> Even if its cheaper to build small reactor vessels, MANY of the other costs become more expensive in larger numbers. There is no way SMR could beat solar+battery power cost even now. With sodium and other batteries projected to reduce storage cost, it is even more unlikely that SMR could be price competitive in future grids. SMR is the only way that dying western nuclear industry could attempt to deal with ballooni…

To a first approximation, China does not build nuclear power. Nuclear's share of power production in China is 4% and dropping. It seems to me that the main reason China keeps building a relatively tiny amount of nuclear is strategic. Reasons like ensuring they never forget how and ensuring they always have buildable designs so that if something changed they could ramp up the program. And probably even more likely: nuclear expertise is important to the country's military.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#52

Post by DanTheManPR » Fri, Aug 28, 2026, 2:26 PM UTC

arpinum wrote: post #23

hwillis wrote: post #14

And a contrasting article from IEEE: https://spectrum.ieee.org/the-forgotten-history-of-small-nuc... > Samuel B. Morris, the general manager and chief engineer of Los Angeles’s Department of Water and Power, traveled all the way to Geneva in 1955 to attend the first International Conference on the Peaceful Uses of Atomic Energy. There, he made a case for small reactors, arguing that because the “number of small units…

SMR is driven by funding, insurance, and regulation. China doesn't have these issues and builds conventional at a great price. China is building 37 reactors, only 4-5 are SMR-type units, and are larger at 600MW. The rest are standard PWR, and the 40+ in planning are dominating by standard PWR. Regulatory risk is too high, building too infrequent to understand costs, funding for first-of-its-kind is too hard for nucle…

This is an important point: in a lot of ways, SMRs are a strictly worse than 1000MW plant. The potential financial benefits come from all the other factors you mentioned. I would rather have a "worse" nuclear power plant that actually gets built.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#53

Post by wing-_-nuts » Fri, Aug 28, 2026, 2:27 PM UTC

jauntywundrkind wrote: post #6

They're all ridiculously fuel inefficient and we're going to have to figure out how to dispose of thousands or tens of thousands of these reactors. Aside from that one that starts pre buried, where the plan is to just leave a spent nuclear reactor buried in a hole. A cost that will almost certainly be externalized to the taxpayers. The promise here is the rich fleecing the average citizen. Getting downvoted wicked ha…

'Fuel efficiency' is not the bottle neck to getting more clean energy on the grid, scale is. Waste? grind it up, vitrify it, bury it in an abandoned coal mine or something. People get more radioactivity from a coal power plant than they will ever get from properly handled nuclear waste.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#54

Post by roryirvine » Fri, Aug 28, 2026, 2:27 PM UTC

samizdis wrote: post #30

Hmmmnnnn. I remember getting excited reading a Wired article "Let a thousand reactors bloom" [0] - but that was back in 2004. I'm still waiting for a "pizza-safe" pebble-bed reactor. [0] https://www.wired.com/2004/09/china-5/

This Nature article dubs TRISO fuel as "accident-tolerant", which is just as well given the lamentable history of it in actual use.

https://en.wikipedia.org/wiki/AVR_reactor for instance, which suffered so many accidents that it was known as the "Shipwreck". It ended up with TRISO pebbles getting stuck in the reactor vessel, the primary circuit being hopelessly contaminated with fission products, and is now impossible to safely decommission using current technology.

It seems to me working SMRs really would be valuable, particularly for off-grid applications or where process heat is needed alongside electricity generation.

But as someone who was, like you, taken in by the pebble bed hype last time around, I've now learned to be much more sceptical about new nuclear technologies until they've actually been proven in practice.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#55

Post by dathinab » Fri, Aug 28, 2026, 2:29 PM UTC

hn_submit wrote: post #5

Although generally safe these reactors aren't totally safe. I'm concerned lax physical security will allow miscreants to blow them up and spread nuclear materials over a wide area. The ensuing panic would totally destroy any goodwill nuclear power has gained over the last 20 years or so. I'm also concerned these things will mostly be used by Big Tech for their A.I. data-centers playing the Good Samaritan with their c…

> A.I. data-centers

I wouldn't be so sure about that (in the US).

Like usage in A.I. data-centers assumes

that they get price competitive with low quality gas turbines run by state subventioniere natural gas...

or the government actual enforces proper environmental protections so that they can't continue running gas turbines without proper filters (and this isn't even (mostly) about climate change, but air pollution harming people)

and from how it currently looks both things seem unlikely :/

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#56

Post by wing-_-nuts » Fri, Aug 28, 2026, 2:29 PM UTC

DennisP wrote: post #43

bell-cot wrote: post #28

Nuclear power's biggest problem is that it attracted, even back in the 1940's, a figurative army of techno-utopians - whose pie-in-the-sky promises of electric power too cheap meter, flying cars, and better-than-Santa's-sleigh safety were not quickly and loudly contradicted by people who knew better. Probably didn't help that many of those keeping quiet had obvious short-term interests in promoting "nuclear everythin…

Sure, and none of solar's advocates are utopian at all .

I don't think solar even needs advocates at this point. Battery backed solar should win on pure economics.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#57

Post by pfdietz » Fri, Aug 28, 2026, 2:29 PM UTC

bell-cot wrote: post #36

pfdietz wrote: post #22

Earlier quoted context omitted.

I wish this subduction zone idea would just die. It's dumb. Things move so slowly it wouldn't help, and subduction zones have large amounts of volatiles coming back up via mud volcanoes and, later, actual molten rock volcanoes. If you want to dispose of waste deep in the sea floor do it far away from subduction zones. Or just store it cheaply in dry casks and minimize the net present value of the cost of dealing with…

Short-term, subduction zones are deep , maximizing the difficulty for malicious actors trying to get their hands on the waste. The subduction itself is more a marketing feature, for folks who oppose putting the waste anywhere on the surface of the Earth. Longer-term - it's mid-ocean ridges, not subduction zones, where you find all the volatiles and volcanoes. Yes, millions of years in the future, some micro-percentag…

> Longer-term - it's mid-ocean ridges, not subduction zones, where you find all the volatiles and volcanoes.

That's simply not true. Yes, there are volcanoes at mid-ocean ridges, but subduction zones also have plenty of activity.

https://en.wikipedia.org/wiki/Mud_volcano

"There are 10 active mud volcanoes in the Izu–Bonin–Mariana Arc which can be found along a north to south trend, parallel to the Mariana trench.[43] The material erupted at these mud volcanoes consists primarily of blue and green serpentinite mud which contains fresh and serpentinized peridotite material from the subduction channel. Fluid from the descending Pacific Plate is released by dehydration and alteration of rocks and sediment."

https://en.wikipedia.org/wiki/Volcanic_arc

(for description of how subduction zones create magmatic volcanoes)

Subducted material is very wet, and as it descends the volatiles ascend to melt the rock above, creating magma (water reduces the melting point of rocks just like it reduces the melting point of sugar.)

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#58

Post by briffle » Fri, Aug 28, 2026, 2:33 PM UTC

hwillis wrote: post #14

And a contrasting article from IEEE: https://spectrum.ieee.org/the-forgotten-history-of-small-nuc... > Samuel B. Morris, the general manager and chief engineer of Los Angeles’s Department of Water and Power, traveled all the way to Geneva in 1955 to attend the first International Conference on the Peaceful Uses of Atomic Energy. There, he made a case for small reactors, arguing that because the “number of small units…

> If it's so much cheaper to build multiple small reactors, just build one big plant with 24 small reactors.

That is literally the plan with several designs like NuScale (and I think TerraPower). The plan with NuScale is to ship the reactors on rail or barge, and then truck it in the last few miles. So they cost savings is in not having to custom desgin the actual components for each site, and build them on site. Standard reactor, standard monitoring systems, standard control room able to monitor multiple reactors, etc.

Plus, when you have 12 of them onsite in one large area, you can take one offline for refueling, and still produce power with the rest of them.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#59

Post by pfdietz » Fri, Aug 28, 2026, 2:38 PM UTC

briffle wrote: post #58

hwillis wrote: post #14

And a contrasting article from IEEE: https://spectrum.ieee.org/the-forgotten-history-of-small-nuc... > Samuel B. Morris, the general manager and chief engineer of Los Angeles’s Department of Water and Power, traveled all the way to Geneva in 1955 to attend the first International Conference on the Peaceful Uses of Atomic Energy. There, he made a case for small reactors, arguing that because the “number of small units…

> If it's so much cheaper to build multiple small reactors, just build one big plant with 24 small reactors. That is literally the plan with several designs like NuScale (and I think TerraPower). The plan with NuScale is to ship the reactors on rail or barge, and then truck it in the last few miles. So they cost savings is in not having to custom desgin the actual components for each site, and build them on site. Sta…

NuScale infamously failed to get their reactor funded in Utah (UAMPS and the CFPP), it was just too expensive. Costs kept rising, large utilities declined to sign up, and in the end those utilities remaining were going to hit the contractual off ramp so it was just cancelled. I have some links to minutes of municipal utility meetings in Idaho Falls that showed the wheels coming off (even though there was great local support for the effort.)

Their design requires considerably more steel and concrete per MW(e) than a large conventional PWR power plant. You don't do civil construction in a factory, and that's where much of the cost is. Their design appears to have it roots in the (false) idea that what was holding back nuclear was perception of safety, rather than cost.

Re: Smaller reactors bring nuclear power closer to fulfilling its promise

#60

Post by bryanlarsen » Fri, Aug 28, 2026, 2:40 PM UTC

inglor_cz wrote: post #50

soco wrote: post #3

With solar and batteries getting cheaper and cheaper, is this still a topic? Or at least for the time being until that "cheaper" gets cheaper enough?

Scaling is a problem. How many batteries do you need to power, say, entire Scandinavia during winter? That would be a lot of lithium, btw. "Dunkelflaute" periods when it is dark and no wind to run the wind turbines are common in northern winters, IIRC the longest one a few years ago was 12 days long. Which means that in order to have a reasonable buffer against it, you would need enough batteries to supply the entire…

That 12 day event was a regional event in Germany, there was still lots of wind in the North Sea. And sun & wind didn't drop to 0, it dropped below 10%.

Dunkelflaute's are a German phenomenon: the standard pattern in most of the world is that the high pressure systems that suppress winds are generally sunny. And the high elevation areas in Germany are sunny during a dunkelflaute.

IOW, batteries aren't the only answer required to cover a dunkelflaute.