Minor Actinide Burning Lmfbr Core System to Enhance Safety Characteristics

A minor actinides (MAs)-burning core system is proposed for future LMFBRs. It provides high-bumup, a long cycle length and enhanced safety characteristics. MAs are transmuted in two steps. MAs are mixed into the blanket fuel only. Pu, reprocessed from discharged blanket fuel, is mixed into the core fuel of an axially heterogeneous core (AHC). Advantages of this MAbuming system include reduction of sodium void reactivity by not mixing MA into the core fuel, introduction of an above-coresodium-tilled-gap (ACSG) region into the AHC and intrcmiuction of a solid moderator into the internal blanket and thin layer region between the ACSG and the upper axial blanket. Evaluation of the equilibrium cycle core performance shows the feasibility of a cycle length of 24 months, a high burnup of 200GWd/t and a breeding ratio of over 1.2.