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Comment by rkangel | Hacker News Reader

I firmly believe that iteration is the key to good engineering. SpaceX has got where they are (partly) due to running flight after flight with incremental improvements each time. The problem with the massive reactors is that you get to build only a couple of them, so you never get to take advantage of learnings to make the next one better/cheaper/quicker.

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So basically it's one economy of scale (making something bigger means the costs for safety, maintenance, personnel etc. are proportionally lower) vs. another economy of scale (making more of one thing decreases the costs per "unit"). Place your bets...

About your comparison to SpaceX: the approach of building a rocket, launching it, letting it explode and then using the gathered data to make the next one explode later (or not at all) is fine for rockets, but I wouldn't want to see it applied to nuclear reactors.

I do agree on not letting nuclear reactors explode, but I did use the SpaceX example on purpose. Before SpaceX started to do it, the concept of iterating to that degree on rockets was unthinkable. There was a self reinforcing loop of "rocket launches are expensive, so we must plan for every contingency, so the launch cycle is long and expensive". SpaceX proved that wrong.

I think small modular reactors are the way out of the similar cycle we've got for nuclear reactors. And I think that building a small number of large ones is going to be a lot better if we're also building a large number of small ones and learning.

It's like not building a y houses for 30 years and then building a massive skyscraper. If that's all we do then we'll only ever have one way of building a skyscraper because there's no room to experiment on other construction materials and techniques.

>Before SpaceX started to do it, the concept of iterating to that degree on rockets was unthinkable.

I'm pretty sure that was what NASA was going to do all the way back in the 70s before their funding got slashed. It was a novel idea but not a novel idea that SpaceX was particularly responsible for, just one they threw capital at because the government stopped caring after the space race.

Nuclear power research, by contrast, never really suffered from a lack of available funds. They were throwing money at mini reactors back in the 90s, saying all the same stuff about how mass production would bring down the price.

NASA funding far exceeds SpaceX’s and always has. It shouldn’t take 4% of the US federal budget (NASA funding during Apollo) to run a hardware-rich design process!

Apollo was wound down because the government wanted NASA to focus on the space shuttle and all sorts of other things as well as slashing the total budget by a huge amount.

So, while in theory it may have had the money, in practice it did not.

The Shuttle cost $48 billion to develop in inflation-adjusted dollars — contrast this with the ~$5B spent on Starship development thus far. It’s hard to defend the claim that NASA is or ever has been under-funded.

NASAs "do stuff" budget is super small because their "keep all the experts on staff" budget is insatiable.

It's not entirely bad though, I'm sure lots of those folks are doing good and important stuff. But I don't think the balance between employment and building things is quite right. At least to my tastes.

if you don't care about any externalities (like spacex), sure. but I doubt hospitals or just normal people who need electricity would be super happy about power sources failing because the people building them subscribed to the "move fast/break things" mentality instead of actually building reliable/safe infrastructure at the cost of it taking longer

Our energy infrastructure isn't particularly reliable right now. Power outages, while not at the level of a third world country, are quite frequent. Nuclear is the highest energy density power generation you can get. Investing in reactors that are less susceptible to explosions (Like a molten salt reactor) is an important step and it's really only viable if you can iterate which means building modular reactor. If you read the article you'll see that most of their iteration and experimentation is without the nuclear material. Something that is possible because the reactor itself is small and can be run through a bunch of safety checks without the dangerous parts.

The route that Nuscale and Kairos are taking is both cheaper and safer than large scale reactors. And we are going to need something to fill the gaps when there is no wind or solar generation available if we want to get off fossil fuels.

We have been attempting "small modular reactors" since the 1950s. They've never worked out. In the same sense that tiny coal plants never worked out.

Large physical scale is everything with old school power generation technologies due to various scaling laws.

https://spectrum.ieee.org/the-forgotten-history-of-small-nuc...

We have plenty of small but commercially successful natural gas plants, so it doesn't seem to be a general principle. The only scaling law mentioned in your article is this:

> a 400-MW reactor requires less than twice the quantity of concrete and steel to construct as a 200-MW reactor, and it can be operated with fewer than twice as many people. Writing in Science in 1961, a senior member of the AEC worried that “competition [from fossil fuel plants] is indeed formidable” and suggested that “with current pressurized-water reactor technology, lower nuclear power costs can be achieved most readily with large plants.”

Almost all the SMRs we've built have been water cooled reactors, which require a large amount of concrete and steel. Newer designs, such as molten salt reactors, can use a lot less, because they operate near atmospheric pressure, don't have to leave room for a high-pressure pipe break introducing a large volume of steam, and have nothing that can cause a chemical explosion. They're also inherently stable and adaptive to load, with little need for active control. A small modular MSR could well work out.

The US has been successfully producing small modular reactors since the 1950’s. We just happen to install virtually all of them inside of submarines and aircraft carriers.

For the least price sensitive customer in the world: The US navy. That doesn't tend to translate into working products on cutthroat markets.

I’ve actually been aboard a Nimitz-class aircraft carrier, where I observed flight operations from the flight deck. I can assure you that it’s a working product. And the Navy is under a lot more pressure to cut costs and economize than many government projects.

> Power outages, while not at the level of a third world country, are quite frequent. Nuclear is the highest energy density power generation you can get.

Well that is more because the American grid is suffering from a mountain load of neglect-debt to a tune that paints the infamous German railways as saints - the Camp Fire for example was most likely caused by a C-hook breaking after many, many decades of neglect [1].

Here in Europe, we get by just fine with outages measured in maybe a dozen minutes (!) a year [2] - Germany got rid of all nuclear reactors, many old ones in other countries were retired as well (Fessenheim, the most infamous one, in 2020), and while there are new builds, they are often decades late and many billions over budget.

How do we do this? We have strict regulations across the board (mandating stuff such as resilience against bad weather, unlike Texas which IIRC refuses to tie in to the other US grids to avoid such regulation), a cross-continental spanning grid [3], and most especially... we just love to bury our cables belowground, so even in the case lightning or storms hit, the actual impact on the consumers is all but negligible. And as the infamous summer of 2023 shows, the power grid still didn't fail even as dozens of NPPs in France and Switzerland had to completely shut down or significantly reduce output because there was not enough cooling water [4]. Hell we even manage to supply an entire country at war with decent power, despite Russia continuously attacking the power grid.

[1] https://www.nbcbayarea.com/news/local/long-term-wear-found-o...

[2] https://de.statista.com/statistik/daten/studie/37960/umfrage...

[3] https://www.entsoe.eu/data/map/

[4] https://www.reuters.com/business/energy/high-river-temperatu...

Worth mentioning here that the SpaceX Falcon is the world's most reliable rocket, with a full success rate of 99.24% out of 394 total launches, 325 successful launches of the current version, and 98.5% successful booster landings of the current version, something no other orbital launch system even attempts.

https://en.wikipedia.org/wiki/List_of_Falcon_9_and_Falcon_He...

Comparisons to other rockets here:

https://arstechnica.com/science/2022/02/spacexs-falcon-9-roc...

https://www.guinnessworldrecords.com/world-records/most-succ...

At the moment, of course, two astronauts are stuck on ISS after Boeing's new spacecraft, developed along more traditional lines, experienced problems in its first crewed flight. They're awaiting rescue by SpaceX's Dragon, which has flown 16 times with crew and delivered astronauts to the ISS 10 times, all without a glitch. Both companies were awarded their crew contracts in 2014.

and nuclear reactors are incredibly reliable as well. do the ends always justify the means?

Since I don't see moral deficit in the means involved in either example, I don't understand the point of your question.

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