Earlier quoted context omitted.
What percentage of potential energy is extracted? My (old, probably out of date) understanding is that (at least in Canada) nuclear facilities limit themselves to extracting some tiny quantity of the potential energy in order to avoid producing material that could be made into nuclear weapons.
Normal nuclear reactors only extract single-digit percentages of the energy. You want to use breeder reactors to actually burn all the nuclear fuel. The "waste" still contains almost all of its energy. Breeder reactors are of course unpopular politically, because they create raw material for nuclear bombs as part of their normal operation.
The first is that they are more expensive than burner reactors. With uranium ore being cheap and plentiful, and with the energy cost of enrichment so low now (gas centrifuges using 50x less energy than gaseous diffusion), there's no economic case for reprocessing, let along breeding.
The other problem is that fast breeders are inherently dangerous, with the possibility of fast supercriticality lurking in a serious accident. Edward Teller famously pointed this out publicly in 1967:
"For the fast breeder to work in its steady-state breeding condition you probably need something like half a ton of plutonium. In order that it should work economically in a sufficiently big power-producing unit, it probably needs quite a bit more than one ton of plutonium. I do not like the hazard involved. I suggested that nuclear reactors are a blessing because they are clean. They are clean as long as they function as planned, but if they malfunction in a massive manner, which can happen in principle, they can release enough fission products to kill a tremendous number of people. […] ...But, if you put together two tons of plutonium in a breeder, one tenth of one percent of this material could become critical. […] I have listened to hundreds of analyses of what course a nuclear accident can take. Although I believe it is possible to analyze the immediate consequences of an accident, I do not believe it is possible to analyze and foresee the secondary consequences. In an accident involving a plutonium reactor, a couple of tons of plutonium can melt. I don't think anybody can foresee where one or two or five percent of this plutonium will find itself and how it will get mixed with some other material. A small fraction of the original charge can become a great hazard."