But if subsequent plants are built with same drawings, you don't have a design engineering firm having to create that work from scratch. Should that alone not save money?
Not to mention the hundreds of small decisions related to "X part supplier went out of business. Y part is similar with a slightly different alloy and mechanical properties, is it a suitable replacement? how can we verify this?"
The original design teams would have auxiliary artifacts that were vetted, and tribal knowledge to help quickly answer these questions. Subsequent design teams will not. The timescales between plant construction exceeds most engineer's memory at 5-10 years.
We have newer reactor designs, materials, and engineering knowledge today that could significantly reduce cost just in material savings or construction time.using something like FAST reactor, is significantly different that the older tech and could save 90% on fuel and waste.
Unfortunately most of the new reactors built in the US and Europe have run massively over time and over budget, despite new technology. Vogtle 3&4 in Georgia drove Westinghouse bankrupt. These were modern AP-1000 models. Flamanville 3 in France (an EPR) is running nearly triple its cost estimate and the delivery time ballooned to 15 years. Olkiluoto in Finland (the first EPR) went massively over time and budget as well. These reactors were specifically designed to be more cost-effective and promised much lower prices, but failed to deliver.
The problem in the nuclear industry isn't the technology itself, but the fact that they consistently fail to deliver projects within their allotted time and budget. Unfortunately this shows no signs of changing, and renewable energy industry looks poised to completely out-compete them in the energy market.
I say this all as someone that used to have high hopes for nuclear tech, after working in nuclear physics research all throughout university.
Thus, breeders generally end up being more expensive than a conventional BWR or PWR.
Here I should mention that I spent some time in nuclear physics research. There's a lot of misinformation floating around about nuclear energy. Most of the "miracle solutions" don't live up to their promises (especially thorium tech and breeders). If they did, we'd already be using them -- nuclear engineers are not fools, and most of these reactor concepts have been kicked around for literally decades.
One other point: the physics behind breeders and conventional slow-neutron reactors isn't fundamentally different. Both neutron capture ("breeding") and fission ("burning") reactions happen in both, the ratios in a breeder are just optimized to favor the first process more. In fact in conventional light water reactors, around a third of the energy released comes from fissile isotope bred from fertile isotopes such as U-238.
I'm not saying that the engineers are idiots. But there are some engineers (supported by government or corporate funds) still building new prototypes and testing new designs, such as FAST. Especially in the US, a driving reason that new designs aren't used is that there have been few built I'm recent decades - partially due to lower cost alternatives and also due to public opinion.
> eliminating the need for ever increasing safety tech and complexity of it for conventional reactors would be a cost savings
Passive safety features are useful, but they don't end up replacing active features (you still need to control the reactor during normal use). At best they might allow for reducing the redundancy level on a critical system -- which might save a bit bit of money, although not much.
Better safety is always a great feature in general, but it's not close to making breeders cost competitive on its own.
> Not to mention the clean up costs when you compare to a conventional reactor that could melt down, even if it's rare.
Actual meltdowns are exceedingly rare (and catastrophically expensive + devastating), so you don't really factor them into the cost equation for a normal reactor.
> Especially in the US, a driving reason that new designs aren't used is that there have been few built I'm recent decades - partially due to lower cost alternatives and also due to public opinion
Mostly cost tbh -- nuclear energy has been historically somewhat unpopular (especially after major accidents) but there's a lot of industrial projects that continue anyway despite being unpopular (oil pipelines etc). The financials for nuclear reactors are not great (it's a big, financially high-risk investment that takes decades to really pay off), so there's less incentive.