Burnup optimization of Small Natural Circulation Lead Cooled Fast Reactor

SNCLFR-100 (Small Natural Circulation Lead Cooled Fast Reactor with 100 MWth), proposed by University of Science and Technology of China (USTC), is a typical modular fast reactor with an array of heterogeneous square fuel assemblies using MOX as the main fuel located in the core, and a preliminary conceptual design has been presented. To extend the full power operating time of the core to 10 years without refueling and improve the transmutation capability of the core, the design optimizations were carried out in this paper, including changing compositions of the fuel, adjusting the relative portion of Pu and U, and changing the type of structure material in the core. In addition, relevant parameters were also optimized. Compared to the original design, the neutron flux distribution became flatter, and the power peak factor of the core dropped from 1.40 to 1.37. The MA transmutation ratio of the optimized core came out to be 2.73%. At the same time, the worth of control rods and the negative reactivity coefficients showed the core has inherent safety.