Study on Reactivity Variation and Its Influencing Factors of Lead-cooled Traveling Wave Reactor

Lead-cooled traveling wave reactor has outstanding advantages of good safety, long refueling and shuffling cycles, and high utilization rate of uranium resources. It is one of the key development directions of advanced nuclear energy system. Realizing the small change of reactivity is the key technical problem in the core scheme design of lead-cooled traveling wave reactor. Taking the physical scheme of lead-cooled traveling wave reactor with thermal power of 700MW and metal fuel as the research object, this paper focuses on the influence of the design parameters of core ignition zone and breeder zone on the effective multiplication factor (k_eff), and analyzes the change trend of core reactivity in the whole life. The numerical results show that ignition zone design parameters significantly affect the initial k_eff of the core. The larger the amount of fissile nuclides in the ignition zone, the larger the initial k_eff. The variation range of reactivity can be effectively reduced by adjusting the axial position of the ignition zone in the core and its fuel enrichment; The higher the ratio of convertible nuclides to fissile nuclides loaded in the core, the more ²³⁹Pu produced by breeding, and the better the overall breeding performance; The longer the breeder zone, the longer the duration of equilibrium state and the longer the core life. The conclusions of this paper can provide an important theoretical basis for the physical scheme design of lead-cooled traveling wave reactor core and the selection of key parameters.