[Background] Nuclear reactor structural material activation analysis is an important part of nuclear reactor radiation safety analysis. The traditional cell-based activation analysis method can not describe the non-uniform spatial activation effect inside the structural material cells, resulting in a large deviation between the activation source and the dose results, so it is necessary to carry out the high-resolution activation analysis method for nuclear reactor structural materials. [Purpose] This study aims to develop a high-resolution activation analysis method for nuclear reactor structural materials based on mesh activation analysis, and establish an integrated mesh-based activation analysis code (MCFisMA). [Methods] First of all, based on Rigorous 2-step method (R2S), Monte Carlo particle transport program MCNP and activation calculation program FISPACT, the mesh-based activation method was used to divide the structural material model into fine spatial mesh, and the activation calculation of each mesh was carried out in turn to realize the precise activation calculation analysis of nuclear reactor structural materials. Then, the MCFisMA was implemented by using the neutron transport method, material activation method and activation-induced dose coupled together. In addition, NUREG/CR-6115 PWR model was used to study the application of high-resolution activation analysis of structural materials. [Results & Conclusions] The correctness and reliability of the proposed method and MCFisMA program is verified with the ITER shutdown dose rate (SDR) benchmark. The method presented in this paper has theoretical significance for improving the calculation accuracy of the activation source term and decay gamma dose field of nuclear reactor structural materials. It provides theoretical and data support for reactor shielding design, overhaul and refueling plan and decommissioning strategy. © 2022 Science Press. All rights reserved.
