Long-term nuclear waste management: Present status and alternatives

Long-term nuclear waste management deals with the final and irreversible stage of waste disposal, on surface and in deep geological formations (according to the waste type), when institutional surveillance is over. There are presently two main options available to deal with the wastes generated by spent nuclear fuel unloaded from reactors and containing most of the radiotoxicity produced all along the nuclear fuel cycle. Since the end of Word War II, spent-fuel reprocessing technology has gone through three different stages, ending up with considerable technical achievements and large investments (construction of large facilities, UP3 in France and THORP in the UK). However, having to face spent-fuel risings and lack of reprocessing capacities, since the mid-seventies some countries are considering the possibility of direct spent-fuel disposal without reprocessing. These two options are discussed in terms of long-term waste management. Because of the types of waste conditioning and packaging adopted with present reprocessing technology, in that case long-term safety, after a few centuries, relies completely on the geological barriers. On the other hand, long-term safety with the second option is based essentially on the retention properties of uranium oxide with respect to actinides. Finally, alternatives such as chemical partitioning of minor actinides followed by their transmutation, either in reactors or using high-energy particle accelerators, are under discussion. Apart from the standard reprocessing (after a cooling period of 3-5 years), all the other options called for a long period (50 years) of interim storage, preventing the adoption of irreversible, costly and not well proved waste management solutions, and leaving time to develop and assess these alternative methods. (orig.)