Impact of Advanced Fuel Cycles on Geological Disposal

Advanced nuclear fuel cycles aim at making more efficient use of the available resources, reducing the risk of proliferation of nuclear weapons, and facilitating the management of radioactive waste. The impact of a number of representative advanced fuel cycles on geological disposal has been investigated. The thermal output of the high-level waste arising from advanced fuel cycles in which all the actinides are recycled is reduced with a factor 3 for a 50 years cooling time in comparison with the spent fuel arising from the once-through fuel cycle. This allows for a significant reduction of the length of the disposal galleries and of the size of the repository. Recycling all the actinides strongly reduces the radiotoxicity in the waste. However the reduction of radiotoxicity has little impact on the main safety indicator of a geological repository, i.e. the dose in the case of the normal evolution scenario; this dose is essentially due to mobile fission and activation products. The deployment of advanced fuel cycles will necessitate the development of low activation materials for the new nuclear facilities and fuels and of specific waste matrices.