Abstract: In the development of fourthgeneration reactors, thoriumbased reactors, such as thoriumbased molten salt reactors, have emerged as an important research direction. Due to factors such as the abundance of thorium reserves, utilizing neutroninduced 232Th radiation capture reactions to produce 233Th is a crucial reaction in thoriumbased reactors for generating fissile isotope 233U. In this study, Monte Carlo method is employed to define a comprehensive utilization coefficient that evaluates the target material and neutron utilization efficiency. The relationship between the utilization coefficient and target material thickness is obtained through polynomial fitting, considering the influence of different incident neutron numbers. Finally, the optimum target material thickness for this reaction is determined to be (1.980±0.002)cm.

Key words: thermal neutrons, Geant4;232 Th(n,γ)233 Threactions, target optimization, comprehensive utilization coefficient