Hybrid burnable absorber design based on ATF and application in 24-month long cycle fuel management

In order to meet the requirement of reactivity control for 24-month long cycle, an optimization design of burnable absorber based on accident tolerant fuel (ATF) is carried out. The design of hybrid burnable absorber which combines low 10 B coating loading in a higher number of fuel rods with high mass content of gadolinium oxide (Gd 2 O 3 ) in a lower number of fuel rods in the fuel assembly, is proposed. The study show that the design can effectively balance the performance parameters of the fuel rod, prolong the reactivity hold-down and achieve the 24-month long cycle. For the 24-month long cycle designed with hybrid burnable absorber, the key parameters of the reactor core meet the requirements of safety-related acceptance criteria, and the maximum power peaking factor during the cycle remains low, and the power distribution is well flattened. Furthermore, the fuel economy is equivalent to the 18-month cycle, significantly enhancing the operational benefits of the nuclear power plant. Fuel rod performance assessment—including rod internal pressure, fuel centerline temperature, and cladding oxide-layer thickness—indicates that all key parameters meet current design criteria.