Summary
Based on the favorable neutronic performance, T/H (thermal‐hydraulic) characteristics and inherent safety of the lead‐cooled fast reactor (LFR), University of Science and Technology of China performed a preliminary design of the 1000Mth medium‐power modular lead‐cooled fast reactor M2LFR‐1000. To solve the core optimization problem of M2LFR‐1000, an automatic core design code named CODOPT (core design and optimization) was developed, considering geometry, neutronics and thermal‐hydraulics. CODOPT starts from setting a number of the core design schemes, then evaluates their key neutronic and T/H characteristics automatically and finally finds the design schemes satisfying the design constraints. Using this code, the sensitivity analysis of the key design parameters (fuel rod diameter, pitch diameter ratio, and inlet coolant velocity) is carried out. Under the neutronic and T/H design constraints, the optimization problem of the core has been studied using a multi‐objective function, which tries to find an optimal design with larger Keff, flatter power distribution, and minimum temperature of cladding and pellet. Current results show that the overall neutronic and T/H performance of M2LFR‐1000 can be improved by choosing the design parameters presented in this paper. The automatic core design ideas adopted currently can also provide some reference for future LFR designs.