ensabah6 said:
Is there a reason that all proposed new nuclear plants, both in the US and in the world aren't being built as "breeder" with on-site reprocessing? Without specific numbers, I do not know the relative costs of designing on-site reprocessing versus once-through then storage. Is any on-site reprocessing, breeder reactor either in commercial operation or planned to being built anywhere in the world (say France or Japan or Uk or Korea?)
In nuclear technology, one advances slowly, and there's a long way between prototyping and commercial exploitation - partly also due to extremely conservative regulatory bodies.
The current reactors are mainly PWR and BWR, thermal water reactors. There are other types too, but they all have a very long history, and a lot of practical experience. These reactors are what one calls "thermal reactors", not because they generate thermal energy, but because they work with "thermalized" or slow neutrons. It is a physical property of the nuclear interactions that the breeding one can obtain (the conversion of "inert" U-238, the bulk of the natural uranium - 99.3% - into burnable plutonium), that is, the amount of "bred fuel" over "used fuel" is less than one ; for a water reactor this is even only 60%. As such, with thermal reactors it is not possible to use the bulk of the U-238 as fuel through breeding: we throw away about 99% of the natural uranium with water reactors (95% of the enriched uranium, and all the depleted uranium). That's the "once through" cycle.
It is *evident* that breeders would be *far more* efficient with uranium: about a factor 100 ! Now, in order to use breeders, one needs from time to time to separate the real waste (the fission products) from the fuel/U-238 mixture, and that separation is called reprocessing. One also needs to have enough plutonium to start up a breeder, and that is also obtained by reprocessing spend fuel. Also, reprocessing has the advantage of ONLY putting in the waste, the real waste: the fission products: so it reduces the VOLUME of the waste (but not its activity of course, apart from the plutonium which is now taken out as fuel).
Now, breeder reactors are somewhat more sophisticated than water reactors, as they cannot have cooling water in their core, but things like liquid sodium or so, but these are not such difficult problems, and have been solved in the past. There have been several attempts to have a prototype commercial breeder reactor. There was of course the IFR, but in Europe there have been Superphenix in France, and Kalkar in Germany. Both have been shot down for essentially political reasons (anti-nuclear movement and Greens don't want any improvement in nuclear technology). Of course, there is not much working experience with breeders: that will only come when we will build and use them. That means that one is a bit less sure about their safety and so on - although this doesn't mean that they are objectively less safe: we simply have less data about it. There is one breeder reactor which has been working for 35 years: Phenix in France. It's fuel has been reprocessed already a few times. It is a relatively small reactor of 250 MW e.
There are also a few breeder projects in Japan, but I don't know much about them.
In France, and in the UK, there are now thermal reactors, and a part of their spend fuel is reprocessed in two large reprocessing plants: one in La Hague (F) and one in Sellafield (UK). But without breeders, one cannot really do much with this reprocessed stuff. Yes, one can use the extracted plutonium to re-use it once more in a thermal reactor, making MOX fuel. But that doesn't do much in the overall uranium economy. In fact, as long as one is working only with pure thermal reactors, reprocessing doesn't make much sense - only a little bit. The reprocessing serves essentially to put aside material to be used in breeders. It is our fuel pot for the future. It also conditions waste in a more compact way (vitrified waste instead of spend fuel elements).
The reprocessing in France and the UK is of the classical PUREX style, not the pyroprocessing which is proposed in the IFR, which is far more advanced. On the other hand, there is a lot of industrial experience with it now.
There has been a lot of political opposition to reprocessing and breeders, officially for proliferation reasons, although when you look at it, these reasons seem to be somewhat far-fetched although not devoid of truth. That said, the pyro-processing of the IFR was much more proliferation resistant.
I don't see why in the long run, a breeder must be much more expensive than a thermal reactor. But in the beginning, of course it will be: it is a technology which will still need evolution, development, and gathering of experience.
But for the moment there is a much simpler reason why we don't have breeders: natural uranium is still cheap and abundant. With existing technology, no risks of new developments etc... it is much more interesting for a utility to build a classical water reactor than to adventure in new types, with a lot of political and red tape resistance, and inevitably the costs of new developments. Fuel is a small fraction of the cost of nuclear power, and as long as there is no genuine economical incentive, it is totally understandable that one isn't going to push breeders any time soon from within the private sector.
