Conceptual Design Optimization of Uranium-zirconium Alloy Fuel Core for Modular Lead-based Fast Reactor

In order to deeply study the physical properties of lead-based fast reactor, one of the reactor types of the fourth generation nuclear energy system, and further improve the safety and economy of modular lead-based fast reactor, the core characteristics of modular lead-based fast reactor with different power levels loaded with uranium-zirconium alloy fuel were studied, and it was found that when the core power was raised to a certain level, the breeding advantage of the core could not be fully released within the specified life. Based on this phenomenon, the conceptual design of modular lead-based fast reactor uranium-zirconium alloy fuel core is optimized. Based on the core power level and service life, the appropriate ratio of grid spacing to rod diameter and the effective density of fuel core are selected, and the breeding performance of core is adjusted by adjusting the uranium loading per unit volume and the ²³⁵U loading. Finally, the core reactivity changes are basically matched with the core power and service life, so that the core reactivity hardly changes during the service life. The optimization not only reduces the difficulty of core reactivity control, but also makes full use of the breeding performance of the core. At the same time, the reasonable ratio of grid spacing to rod diameter provides safety and design margin for thermal analysis of the core, which effectively improves the economy and safety of the core.