摘要：The lightweight shielding design of small reactors is a research hotspot. Based on a small helium-xenon-cooled solid reactor, the effects of thickness and number of shielding layers on the radiation dose are first studied. It is found that when photons are shielded first and the number of shielding layers is odd, the radiation dose can be significantly reduced. To reduce the weight of the shielding body, the relative thickness of the shielding layers is optimized by the genetic algorithm. The optimized scheme can reduce the radiation dose by up to 57% and helps reduce the weight by 11.84%. To determine the total thickness of shielding layers and avoid the local optimal solution, a formula that gives the relationship between the total thickness and the radiation dose is established through large-scale calculations, which has an error of 0.8%~7.45% compared with the Monte Carlo method. A semi-empirical and semi-quantitative lightweight shielding design algorithm is proposed to integrate the above works, and a code SDIC1.0 is developed to achieve the optimized lightweight shielding design for small reactors. It has been verified that the error between SDIC1.0 and Monte Carlo code RMC is about 10%, and the time has increased by 6.3 times.