In response to China's future requirements for the transportation and storage of spent fuel, the work aims to explore investigate key issues in radiation shielding design of containers so as to provide a foundation for the development of a safe and cost-effective ductile cast iron spent fuel transport and storage container. A source term analysis was conducted for the loaded spent fuel assemblies, examining the impact of key contributing nuclides and the cooling time of the assemblies on the source term. Further, shielding material selection was carried out by considering the characteristics of the source term and neutron scattering properties, and the impact of manufacturing tolerances in neutron shielding materials on shielding effectiveness was studied. The results indicated that the main contributor to the neutron source term was 244Cm, accounting for 90%, with the energy primarily in the range of 1 MeV to 2 MeV, and it did not decrease rapidly with the increase of cooling time. The primary source of the activation source term was 60Co produced by the activation of matrix materials, which significantly decreased with the increase of cooling time. Considering the source term and thermal characteristics of the container, lead-polyethylene was selected as the neutron shielding material, and requirements for manufacturing tolerances were proposed. In conclusion, the research findings can be applied to the radiation shielding design of ductile cast iron spent fuel transport and storage containers, enhancing their shielding performance and loading capacity, and further improving the safety and cost-effectiveness of ductile cast iron spent fuel transport and storage containers.