Radiation shielding analysis and criticality safety calculation for spent fuel transportation cask

China anticipates a shortage in storage capacity for spent fuels at reactor sites for the AP1000 NPPs within the next 10 to 20 years. We proposed a conceptual design for a transportation cask capable of loading 21 spent fuel assemblies in AP1000 reactors and studied its criticality safety and radiation safety characteristics. Throughout these operations, three key concepts were taken into account: source term, radiation shielding, and criticality calculations. The sources of the 4.95% enriched spent assemblies following a cooling period of 21 years were calculated by the cosNAB code. The results of the source term computation were utilized as input data for the Monte Carlo code cosRMC, which was employed for shielding calculation and criticality safety analysis. The calculation results have verified the feasibility of the design, which can provide a reference for the development of spent fuel transportation casks for the AP1000 reactor.