Nuclear spent fuel management scenarios. Status and assessment report

The strategy for management of spent nuclear fuel from the Swedish nuclear power programme is interim storage for cooling and decay for about 30 years followed by direct disposal of the fuel in a geologic repository. In various contexts it is of interest to compare this strategy with other strategies that might be available in the future as a result of ongoing research and development. In particular partitioning and transmutation is one such strategy that is subject to considerable R and D-efforts within the European Union and in other countries with large nuclear programmes. To facilitate such comparisons for the Swedish situation, with a planned phase out of the nuclear power programme, SKB has asked the team at Royal Inst. of Technology to describe and explore some scenarios that might be applied to the Swedish programme. The results of this study are presented in this report. The following scenarios were studied by the help of a specially developed computer programme: Phase out by 2025 with direct disposal. Burning plutonium and minor actinides as MOX in BWR. Burning plutonium and minor actinides as MOX in PWR. Burning plutonium and minor actinides in ADS. Combined LWR-MOX plus ADS. For the different scenarios nuclide inventories, waste amounts, costs, additional electricity production etc have been assessed. As a general conclusion it was found that BWR is more efficient for burning plutonium in MOX fuel than PWR. The difference is approximately 10%. Furthermore the BWR produces about 10% less americium inventory. An ADS reactor park can theoretically in an ideal case burn (transmute) 99% of the transuranium isotopes. The duration of such a scenario heavily depends on the interim time needed for cooling the spent fuel before reprocessing. Assuming 10 years for cooling of nuclear fuel from ADS, the duration will be at least 200 years under optimistic technical assumptions. The development and use of advanced pyro-processing with an interim cooling time of only 2 years may decrease the duration for transmuting 99% of the transuranium to about 50 years. ADS reactors have turned out to be a necessary component to decrease the americium inventory because neither BWR nor PWR alone can provide prevalence of americium destruction over its production during the operation time. Nevertheless, the economic advisability of these scenarios calls for further investigation. A scenario using in total six ADS reactors during a 100 year period from 2035 to 2135 is analysed in some detail. It would reduce the TRU-inventory projected from the current LWRs from about 100 tonnes in 2025 to about 6 tonnes in 2135. The ADS reactors would produce on the average 840 MWe giving in total some 740 TWhe of electricity during the 100 year period. The costs for the system are assessed to about 95 GSEK for investments and about 62 GSEK for fuel cycle and waste costs (1 GSEK ∼ 140 MUSD). All these numbers depend on some optimistic assumptions concerning ongoing technical development. They are thus subject to large uncertainties. In addition, a combination of LWR-MOX plus ADS has been found somewhat more efficient in reducing the transuranium inventory than ADS alone