Neutronic performance of a thorium based mixed oxide fuel in a burner sodium-cooled fast reactor

Abstract

The paper discusses the feasibility of using the Thorium Mixed-Oxide fuel with transuranic isotopes in a medium-sized Sodium-Cooled Fast Reactor core dedicated for actinide incineration with a capacity of 1000MWth. The core was designed based on the Advanced Burner Reactor 1000MWth studied in OECD/NEA SFR Benchmark. The SERPENT 2.1.31 Monte Carlo computer code with ENDF library was used to perform static criticality, isotopic depletion and safety parameters calculations for five consecutive fuel cycles. The key core parameters, eigenvalue, effective delayed neutron fraction, control rod worth, sodium void, doppler reactivity coefficients and isotopic inventories were investigated at the Beginning-of-Cycle (BOC) and End-of-Cycle (EOC). The results were compared with the medium MOX burner and large thorium core. Thanks to the internal U-233 breeding, the excess reactivity remained positive up to 700 days in comparison to 400 days for the reference core. The core has the ability to operate long campaigns, and at the same time, it is the efficient transuranic burner, with the conversion ratio ∼1. The penalty of the improved cycle was reduced Doppler effect and effective delayed neutron fraction. In comparison to the MOX reference core, sodium void effect was reduced.