Meh I dunno about that! The US poured a few tens of millions into the molten salt breeder reactor program and a few more on the indian point 1 initial thorium breeder core. That's about it in the USA. In Europe, ok there was the THTR-300 which was a pretty big project. This is fluid fuel thorium though, which is quite a lot different from solid fuel. We have spent nearly nothing on fluid fuel so far.
Now if you want to talk about breeder reactors in general (namely on the uranium-plutonium fuel cycle), then yeah that's in the many billions range. That was more for infinite world-scale sustainability rather than cost specifically. LWR converter reactors have always been known to be cheaper than breeders.
Now if you want to talk about breeder reactors in general (namely on the uranium-plutonium fuel cycle), then yeah that's in the many billions range. That was more for infinite world-scale sustainability rather than cost specifically. LWR converter reactors have always been known to be cheaper than breeders.