Fuel recycling, fast-breeder reactors

The fast breeder reactor cycle in this cycle, the spent fuel is similarly reprocessed and the uranium and plutonium fabricated into new fuel elements. However, they are recycled to fast breeder reactors, in which there is a central core of uranium/plutonium fuel surrounded by a blanket of depleted uranium (uranium from which most of the uranium-235 atoms have been removed during the process of enrichment) or to burner reactors. This depleted uranium consists mostly of uranium-238 atoms, some of which are converted to plutonium during irradiation. By suitable operation, fast breeder reactors thus can produce slightly more fuel than they consume, hence the name breeder (see Fig. 7.1). 

Presently, plutonium is used in light-water reactors as MOX fuel and also in small amounts for the development of fast-breeder reactors. Currently 22 power reactors in five countries (France, Germany, Switzerland, Belgium, and Japan) are loaded with MOX fuel and this number is expected to rise to between 36 and 48 by 2000. The use of MOX reduces the inventory of separated plutonium and is regarded as an interim measure before plutonium s possible full-scale use in fast reactors later in the next century. It is known that multiple recycling in light-water reactors degrades plutonium, which in turn limits the number of times it can be recycled to two or three. Such... 

Under some conditions it is economically attractive or environmentally preferable to reprocess spent fuel in order to (1) recover uranium to be recycled to provide part of the enriched uranium used in subsequent lots of fuel, (2) recover plutonium, and (3) reduce radioactive wastes to more compact form. In part II of Fig. 1.11 the recovered 0.83 percent enriched uranium is recycled and the 244 kg of plutonium recovered per year is stored for later use in either a light-water reactor or a fast-breeder reactor. This recycle of uranium to the isotope separation plant reduces the annual UaOg feed rate to 220 short tons, still appreciably greater than for the heavy-water reactor. 

Also shown in Table 8.5 are the actinide quantities of a 1000-MWe fast-breeder reactor operating on an equilibrium fuel cycle with recycle of plutonium and uranium [PI]. The quantity of plutonium to be recovered and fabricated into recycled breeder fuel is greater than... 

Reprocessing fuel cycle (RFC) with mixed oxide (MOX) recycle of U and Pu in light water or fast breeder reactors (FBRs) and disposal of HLW. 

This again delays a decision about what to do with once or twice recycled LWR spent fuel either use it to fuel fast breeder reactors or dispose of MOX fuel in a repository. What is different, is that at least the HLW would contain no minor actinides. 

The fuel cycle concept of the RMWR is basically a closed cycle and is the same as for FBRs (sodium cooled fast breeder reactors). It has been confirmed that the high conversion ratio, more than 1.0 and the negative void reactivity coefficient can be achieved in the RMWR core under the multiple recycling of Pu including advanced fuel reprocessing schemes. 

Utilization of plutonium in early research and commercial orders to fabricate thermal recycle and fast breeder fuels did not coincide in timing with Pu availability from different sources. The plutonium comes mainly from high-exposure light-water reactor fuel reprocessing extended storage of this Pu as a nitrate solution leads to 241 contents up to 3%. For hands-on operation with this material it is necessary to reduce the Am content to about 0.5%. It was also necessary to minimize the liquid waste streams from the plant. In designing a technical-scale process, it was... 

Mwd/ton. Although such a fuel consumption might be obtaine.i in high-neutron-economy converter reactors through recycling of the fuel, it seems likely that even the best such reactor may fall short of this goal and that both fast and thermal breeders will be needed. 

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