Symbiotic equilibrium between Sodium Fast Reactors and Pressurized Water Reactors supplied with MOX fuel

Two different reprocessing strategies are considered. With joint reprocessing of all spent fuels, total and fissile plutonium flows balance for a unique fraction x of EPR™ in the fleet, equal to 0.2547. This x value is consistent with the results reported in the former scenario study mentioned above. When EPR™ spent fuels are used in priority to supply SFR (distinct reprocessing), x reaches 0.2582 at most. COSI6 simulations have been performed to further assess these results. The EPR™ fraction in the fleet at symbiotic equilibrium barely depends on the applied reprocessing strategy, so that the more flexible joint reprocessing constitutes the reference option in that case.