The main challenge facing partitioning and transmutation operations is the need to enter nuclear cycles of extremely long duration: about 200 years. Another disadvantage is the generation of high quantities of intermediate-level long-lived radioactive waste (ILW) which will also require deep geological disposal to be safely managed. A more positive aspect is the expected reduction in size of the repository, which was estimated to be an order of 4 to 6. Both positive and negative aspects were examined in an international benchmark study coordinated by Forschungszentrum Jülich and financed by the European Union.