[CogentHedgehog]

There's a reason countries don't build breeder reactors. Fuel costs are a tiny fraction of the costs for a nuclear powerplant: less than 10%. Breeders save a bit of money on fuel in exchange for a higher capital cost (cost of construction). For reactors, capital costs are a huge factor because reactors are extremely expensive already ($8-10Bn per reactor in the US/Europe). Increasing that further more than balances the savings on fuel.

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.

[giantg2]

With the newer breeders (FAST), the main difference is safety. You don't need the same control mechanisms because they automatically cool down due to the physics of them so that they don't melt down. I'd imagine that FAST reactors eliminating the need for ever increasing safety tech and complexity of it for conventional reactors would be a cost savings (or at least make it close). Not to mention the clean up costs when you compare to a conventional reactor that could melt down, even if it's rare.

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.

[CogentHedgehog]

Passive safety is what you describe. That's a requirement for reactors to be classified as Gen III, so all of the models listed above have some variant of that.

> 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.

[stjohnswarts]

I think people -might- be more on board if they knew the nuke plant sitting a couple of miles away wasn't going to go critical/poison their local acquifer and was provably safe beyond a doubt even to skeptics. I think that's what it will take, otherwise solar will have to be our savior.