Lead-bismuth-eutectic alloy (LBE:44.5 wt.%Pb+55.5 wt.%Bi) has become an important coolant candidate for the fourth-generation reactor due to its good physicochemical properties. However, the radiation protection risk of radioactive polonium caused by liquid lead-bismuth alloy as the main coolant of the reactor has become an important issue that must be paid attention to in the research and development of lead-bismuth reactors. The ²⁰⁹Bi(n,γ)^210gBi reaction is the key source term for the production of ²¹⁰Po in a lead-bismuth-led reactor. Accurate measurement of the ²⁰⁹Bi(n,γ)^210gBi reaction cross section is very important for assessing the risk of radioactive polonium release from a lead-bismuth reactor. At present, the reaction cross section can be measured online by directly measuring the cascade of transient gamma rays of the capture reaction or offline by measuring the ^210gBi decay product ²¹⁰Po. In response to this issue, a digital water bath temperature control system was adopted, and a method for enriching ²¹⁰Po using alpha-spectrometry with isotope dilution was proposed. The method was optimized by adjusting key parameters in the spontaneous deposition process, resulting in a significant increase in the enrichment rate of ²¹⁰Po. This will help solve the problem of low sensitivity in direct measurement of ²⁰⁹Bi(n,γ)^210gBi. The preliminary experimental results show that the technical route has strong feasibility, but the data analysis also finds that there are challenges such as natural polonium background and α-decay spectrum interference of polonium,Artificial intelligence technology will become an important research idea to solve related problems.

Lead-cooledfast reactor;Polonium;209Bi(n,γ)210gBi;Spontaneous deposition; Multi-foil activation technique; Neutron spectrometry