Physical study of an ultra-long-life small modular fast reactor loaded with U-Pu-Zr fuel

The physical characteristics of a small modular fast reactor loaded with U-Pu-Zr fuel were studied in this paper. The reactor can be operated for more than 20 years without refueling. The small burnup reactivity swing was achieved thanks to the good balance between the fuel breeding characteristics and decay of ²⁴¹Pu with a half-life of 14.239 years, which avoids increasing the initial excess reactivity of the core. Nuclide effect analyses in this paper show that the decay of ²⁴¹Pu plays a non-negligible role in burnup reactivity swing for the ultra-long-life low power reactors loaded with U-Pu-Zr fuel. The reactor neutronic parameters such as burnup behavior, displacement per atom (DPA) of the fuel rod cladding, spent fuel composition, and reactivity feedback coefficients were analyzed. The operating modes of the reactor were also analyzed.