Abstract: Based on the lattice counting function of the Monte Carlo program cosRMC, this paper developed a shutdown dose rate calculation program with a strict two-step method as the core. Through coupling particle transport calculation and activation analysis calculation, the shutdown dose field was accurately obtained. The ALARA program was used to carry out activation analysis and calculation. In this paper, the program is applied to the calculation benchmark of ITER diagnostic window, and a full calculation analysis is carried out, which is in good agreement with the shutdown dose rate results calculated by other programs. In order to improve the efficiency of particle transport calculation, the parallel calculation method and the global weight window variance reduction algorithm are applied in the program calculation. In addition, due to the fusion device geometry is complex, the lattice structure is difficult to accurately describe the geometric structure, a lattice often contains more than one cell, at this time of the lattice flux average to shut down the accuracy of dose rate will bring bad effect, rather than the lattice structure has a good adaptability, geometry, therefore, this work is based on unstructured lattice made further development program for shutdown dose rate, The reliability of the program for calculating shutdown dose rate based on unstructured lattice was verified.

Key words: shutdown dose rate, R2S method, cosRMC, ALARA, unstructured lattice