A neutronics concept design of lead-bismuth cooled accelerator-driven system for minor actinide transmutation

Pursuing a high minor actinide (MA) transmutation rate, this paper proposes a neutronics concept design of leadbismuth (LBE) cooled accelerator-driven system (ADS) with burnup reactivity swing less than 1% and proton beam current smaller than 17mA. After a comparison with other types of fuels, Uranium-free metallic dispersion fuel (TRU-10Zr)-Zr is selected to obtain a harder neutron spectrum to transmute MA. With a MA initial loading, the suitable proportion of initial Plutonium to transuranium element (TRU) is found around 33% to make sure that the burnup reactivity swing is less than 1%. The location of the spallation target is optimized to guarantee high external spallation neutron source efficiency and to lower proton beam current. For the subcritical system, initial effective multiplication factor is 0.97, and the thermal power is 1000 MW. For the accelerator, proton with energy of 1.5GeV and a parabolic spatial profile is provided by proton linac. It is demonstrated by the numerical results that the transmutation rate of MA is about 28% after 600 effective full power days (EFPD) while the support ratio for LWR units with the same power is about 46.