It is generally recognized that long term development of nuclear power as part of the world's future energy mix will require fast reactor technology with a closed fuel cycle. The fast neutron spectrum allows fast reactors to largely increase the energy yield from natural uranium as compared to thermal reactors. This high utilization of fuel can extend nuclear power programmes for thousands of years and provide significant improvements in nuclear waste management. It is for these reasons that fast reactors have been under development for decades in several countries, primarily as breeders and, in recent years, also as high-level waste burners.
