Assessment of the Transmutation Capability of an Accelerator Driven System Cooled by Lead Bismuth Eutectic alloy

Any nuclear fast reactor is able to burn and transmute minor actinides (MA), but the amount of MA content has to be limited to a few percent to avoid unfavourable consequences on the coolant void reactivity, Doppler effect, and delayed neutron fraction, and therefore on the dynamic behaviour and control. Accelerator driven system is instead able to safely burn and/or transmute a large quantity of actinides and Long-Lived Fission Products (LLFP), as it does not rely on delayed neutrons for reactor control in normal or accident conditions.This paper summarizes and compares the results of neutronic calculations aimed at evaluating the transmutation capability of subcritical cores cooled by Lead-Bismuth Eutectic alloy and loaded with assemblies based on (Pu, Am, Np, Cm) oxide dispersed in a molybdenum metal or magnesia matrices. It also compares the thermo-mechanical behaviour of these innovative fuels versus some key parameters, namely gas release and pellet swelling.The detailed neutronic calculations were performed with ERANOS code, whereas the sensitivity analysis was carried out by a special ERANOS Procedure, so-called MECONG. The behaviour of fuels pin during the cycle was investigated by using TRANSURANUS code, appropriately modified.The performed analysis shows a good compromise for both fuels between transmutation and core performance at increasing of the core power and the use of CERMET fuels may present some advantages.