KTH Physics

Transmutation of Nuclear Waste

by Alex C. Mueller (CNRS-IN2P3, France)

FA31 ()


A lot of recent work has been devoted to the fact that an important aspect of sustained growth is the long-term availability of energy resources and their environmental impact. Current scenarii typically predict a doubling of the primary energy need for 2050. Yet, on the other hand, an environmental policy is required, that would ensure a major reduction in emissions of green-house gases in order to combat climate change. However, in order to be based on scientific reasoning, a condition for real effectiveness, such a policy has to rely, for each energy-producing system, on a thorough scientific life-cycle analysis of the total environmental impact. Such studies conclude on the attractiveness of nuclear power with respect to its very small CO2 (and other greenhouse gas) emissions. Ranges between 10 – 130 g/kWhelec have been given in various studies, substantially lower than that of any fossil-fuelled power technology for electricity production, and in (often rather favourable) competition with other "renewable" technologies. Indeed, for Europe, the amount of CO2 yearly avoided by the use of nuclear power has been estimated by the European Commission to about 900 million tonnes, i.e. roughly equivalent to the transport sector. Such (and other) facts underline that it seems rather unlikely to reach the 2020 EU CO2 reduction target of 20% without a considerable increase of the nuclear share in the mix of the energy-generating systems to be deployed in the future. For the horizon of, say 2040, for an industrial deployment, a large international effort is presently made on the "generation-4" nuclear reactors that would comply in an ideal way to the criteria of sustainability ("sustainability" means here in particular that the energy content of the (natural) Uranium and of the "breaded" heavier elements is fully exploited. This requires so-called "fast", i.e. not moderated, "generation-IV" reactors, since the fission of these species is essentially induced by the fast part of the neutron spectrum; see section 3 for more and also some quantitative information), safety, reliability, and proliferation resistance. However, the use of nuclear energy is heavily debated in many European countries because of the long-term environmental burden of nuclear waste from the present-"generation-2" (and immediate-future "generation-3") LWR reactors (LWR, light water reactor, using pressurized "natural" water for cooling and moderation is the most often used technology at present). The significance of this subject for Europe may be highlighted by the fact that 2500 tons of spent fuel are produced every year by the 145 reactors of the European Union. It is this context that the prospect of "Partitioning and Transmutation", or P&T may well play an important role. P&T of nuclear waste implements the principle of sustainable development in a rather general way: separating out of the spent fuel (partitioning) the radiotoxic components for recycling them (transmutation) in a way to minimize their toxicity and recover their contained energy in a useful way, in other words, minimizing potential health hazards while optimizing benefit for society.