Google commits to buying power generated by nuclear-energy startup Kairos Power

The selling point of modular reactors is that they are built on a production line and that the next one is identical to the one before. But why not apply this principle to large reactors? After all there are plenty of reactors that operate reliably so why not just dust off the drawings and build another one just like the one before?

In this podcast (1) Jigar Shah (head of DOE’s Loan Programs Office) said:

"...the first one will be more expensive, the second will be cheaper, the third one is cheaper, the fourth one's cheaper. So it is objectively the case that if you went to a 1200 MW coal site, which by definition only has 1200 infrastructure around it, and you built one AP1000, that would be more expensive than building four 300 MW reactors, because the second, third and fourth one will be cheaper than the first one."

1. https://www.volts.wtf/p/nuclear-perhaps said that

Are you implying that building a copy of an existing PWR would be more costly (in real terms) than building the first one? After all the world has quite a variety of first ones already built.

Also claiming certain knowledge of the financial outcome of a large engineering project before one has even a prototype is pretty much the definition of hubris.

The podcast also says that there are 92 reactors operating in the US now and that one of the reasons why the US is so far behind other countries in the nuclear industry is that 'no four are the same'. So why not pick the most successful one and build a copy?

The word cheaper is doing a lot of work here. How much cheaper?

I'm not arguing that modularity is bad just that there doesn't seem to be any hard evidence yet that they will be truly modular, certainly not in the same sense as washing machines coming off a production line are. Look at how many rockets SpaceX built before they got it right.

Even production lines for much simpler things generally take some time to settle down. The idea that the second one will be noticeably cheaper than the first seems rather unlikely because it will have to incorporate fixes for the things that didn't quite work right on the first one.

Also a 300 MWe reactor is still very large machine and has to dump huge amounts of heat somewhere so the site is still important so making the individual reactors cheaper does not make the whole project correspondingly cheaper.

I have no in-depth knowledge in this area and can't offer any answers. However, I listened to the podcast a few months back and it seemed relevant to your original question. I hope you find it useful.