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• Three-dimensional full-scale thermal-hydraulic analysis of fusion blanket is performed after validation of numerical method. • Specific structure modifications are proposed for initial blanket components. • The optimized blanket can satisfy temperature limits for all materials. Fusion energy is widely considered as the most promising method to solve the energy crisis, while the blanket is of vital importance in the fusion device due to its main function of thermal extraction and energy conversion. The high heat flux from plasma and the internal nuclear heat deposition are imposed on fusion blanket. Slice model or two-dimensional model is usually adopted for traditional design of fusion blanket, in which most side effects are neglected, introducing relatively large uncertainty for thermal removal capability of the blanket. In this study, the integral three-dimensional full-scale model is established based on the split-zone method for mesh generation. Based on the validated numerical method, the preliminary thermal-hydraulic analysis of the full-scale model shows that inadequate heat transfer and significant flow distribution difference are encountered for the initial blanket design, in which the full-scale effect is not considered. After that, the specific structure modifications are proposed for different blanket components to solve the abovementioned problems. The maximum temperature of first wall is reduced from 671°C to 639°C, which is under the material temperature limit of 650°C; the inverse V-shaped flow distribution in the cap is modified as more even flow in cap channels; the maximum temperature of the function zone in blanket is reduced from 999°C to 759°C, which is an important structure modification for the blanket. The integral three-dimensional full-scale thermal-hydraulic analysis is performed after the local structure modification. The results show that the function zone is cooled down obviously by the coolant in the side wall. Compared to the temperature limit of 900°C for lithium orthosilicate, there is a more rigorous limit for the beryllium material, since they share the common cooling capability layer by layer while the temperature limit for the latter is only 650°C. The three-dimensional full-scale thermal-hydraulic analysis in our research is valuable to evaluate the integral reliability of the fusion blanket. [ABSTRACT FROM AUTHOR]

• The neutronics and the thermal-hydraulic analyses for multiple operation modes under both the symmetrical and the stepped NWL distributions are conducted. • Under the actual nonuniform NWL distributions, there is obvious poloidal temperature nonuniformity in every functional zone. • The thermal-hydraulic results calculated under the simplified uniform NWL distribution are found to be not conservative. • The degree of the influences of the poloidal nonuniform NWL on blanket performances for multiple operation modes are compared. Helium Cooled Ceramic Breeder (HCCB) blanket is one significant component of China Fusion Engineering Test Reactor (CFETR). The neutronics and thermal-hydraulic performances of the blanket are the bases of the safe operation for CFETR, and both of them are influenced by the neutron wall loading (NWL) distribution on the blanket. In our previous work, the influences of the poloidal nonuniform NWL on the neutronics performances of the CFETR HCCB blanket have been preliminarily investigated. However, as the nuclear heating rate in each blanket component is adopted as the internal heat source for the thermal-hydraulic analyses, it's necessary to further investigate the influences of the poloidal nonuniform NWL on the thermal-hydraulic performances of the blanket. Besides, CFETR aims to cover multiple fusion powers (from 200 MW to 1.5 GW) at the present stage. Therefore, it's also essential to compare the different influences of the poloidal nonuniform NWL on blanket performances for multiple operation modes. [ABSTRACT FROM AUTHOR]