Abstract:The advancement of deepening reforms in the energy structure of the country has underscored the imperative for active development within the domain of nuclear energy, emerging as a predominant trajectory. Representing the forefront of nuclear power evolution, fourth-generation nuclear energy systems have garnered considerable international attention. Particularly, the research into lead-cooled fast neutron reactors has been highly acclaimed on a global scale. Leveraging the open-source reactor Monte Carlo neutron transport equation software OpenMC, developed by the esteemed institution of the Massachusetts Institute of Technology (MIT), this study centers its investigation on the Advanced Lead Fast Reactor European Demonstrator (ALFRED). Employing ALFRED as the focal point, the study meticulously selects and examines two distinct coolant materials for the reactor core, thereby elucidating essential insights into the physical dynamics of lead-cooled fast reactors. The findings delineate that, under identical fuel loading conditions, the utilization of lead-bismuth coolant yields a significant enhancement in the reactor core's initial reactivity by 271pcm. Moreover, the reactor core manifests a heightened proportion of effective delayed neutrons during normal commercial operation. Additionally, the neutron spectrum of the reactor core exhibits broader and harder characteristics, while also showcasing improved burning efficacy for the 239Pu nuclide within the fuel matrix. Consequently, the employment of lead-bismuth alloy coolant within the ALFRED reactor core culminates in a heightened effective multiplication factor. This augmentation holds promise for enhancing the controllability and burnup performance of the reactor core, while concurrently mitigating the generation of radioactive waste. In essence, this study furnishes valuable insights into the design and performance optimization of the reactor core for the lead-cooled fast neutron reactor European Demonstrator.