A sub-channel analysis code for advanced lead bismuth fast reactor

► We obtain the optimum pitch to diameter ratio in PBWFR is 1.27. ► The temperature peak of the coolant lies at the outlet of the rod. ► The cladding surface peak temperature stays near the axial central position. ► The highest coolant temperature of lead bismuth eutectic is under control and the highest cladding temperature is less than the limited temperature. ► Then the hexagon assembly is the best assembly structure.