USED FUEL MANAGEMENT | FUEL & FUEL CYCLE
Above left: Interim Storage Facility for used fuel Source: SKB Above right: Used nuclear fuel in dry storage Source: Holtec
Final disposal The science and technology of engineered underground repositories, often referred to as deep geological repositories (DGRs), is well-understood and some countries are progressing towards their operation. Many geologies are suitable for final geological disposal of used fuel or vitrified high-level waste. Some countries (including Finland, France and Sweden) have gained societal acceptance for DGR sites, whereas other countries are finding the siting process to be challenging. In the USA, the Waste Isolation Pilot Plant (WIPP) deep geological disposal facility for defence-related transuranic waste has been in operation since 1999.
Although the cost of reprocessing and recycling could
be considered relatively high in comparison to the historic costs for mined uranium, this might change depending on the level of demand for nuclear fuel in the future. This together with the social, environmental and security of supply advantages of reprocessing/recycling mean that it could become the most attractive option for used nuclear fuel management, particularly for advanced reactors and/or fuel cycle systems. Some countries, including Canada, Finland, Spain, Sweden, Switzerland and the USA, have decided to directly dispose of their used nuclear fuel in a DGR. In some cases, this is a political decision but in others it has been judged to be economic considering the prevailing market conditions.
Potential future options The options of either recycling or direct disposal are expected to remain as the fundamental pathways for the management of used nuclear fuel in the future. Moreover, avenues that are being researched and developed to complement these options include: Advanced recycling fuel cycle options such as multi-
recycling of uranium and plutonium in conventional light water reactors and/or transitioning to closed fuel cycles with fast neutron reactors that fully utilise natural uranium are close to full scale demonstration. Both options, which can be implemented sequentially, minimise waste quantities and toxicity thus alleviating some requirements for the design and operation of the deep geological repository. Additional advanced options such as the transmutation of minor actinides are at the early stages of research and development and require significant efforts to reach
commercialisation. These solutions have the potential to significantly further reduce both nuclear waste generation and the decay time of the remaining waste. Deep borehole disposal technologies have been studied
in various countries. However, R&D programmes are still necessary to advance the deep borehole repository concept and to reach maturity both in terms of component technologies and in supporting safety cases. Further develop the use of multinational/regional
infrastructures, including but not limited to repositories, particularly for countries with small nuclear programmes. For multinational deep geological repositories, these will require significant development as well as long-term intergovernmental agreements. The used fuel return schemes currently deployed for
research reactors may be adapted for larger quantities of used fuel arising from commercial activities, with shared reprocessing/recycling and/or disposal infrastructures. This would require the development of innovative commercial terms between national governments, the nuclear fuel cycle industry, reactor vendors and utilities. A longer-term, more ambitious prospective pathway
could be for reactor users to not own the fuel at all. Fuel could be leased from a vendor or just the energy in the fuel could be purchased, with the used fuel being returned to the supplier. However, besides the need to deploy innovative commercial arrangements, this would require long-term intergovernmental agreements to address security of supply aspects. There are legal, regulatory and ethical implications associated with allowing waste generated in one country to be disposed of in another. The development of small and advanced modular
reactors will be secured with similar used nuclear fuel management options as those listed above. Nevertheless, various novel reactor technologies have different challenges for the management of used nuclear fuel, with different life- time costs which should be factored in.
Used fuel and nuclear new-build Used nuclear fuel management considerations should be included as part of the assessment process for establishing new nuclear power programmes or expanding existing ones. The generation of used nuclear fuel, by-products of the operation of nuclear reactors, should not be a barrier to the deployment of new nuclear projects, as solutions for its sustainable management currently exist and innovative options for the future are being developed. ■
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