PROBLEM TO BE SOLVED: To provide a nuclear facility quantity-of-activation analysis method capable of more accurately analyzing and evaluating the degree of activation (quantity of activation, distribution of the quantity of activation) of nuclear facilities.SOLUTION: Priorities are set to respective structures in nuclear facilities, mesh-tally data is created with a mesh size according to each priority, a neutron flux per mesh-tally is obtained by conducting three-dimensional Monte Carlo computation, a radioactive inventory is calculated using the neutron flux per mesh-tally, and spatial distribution data on the quantity of activation of each structure is created. Furthermore, two overlapping mesh-tallies different in priority are read, and an overlapping portion of one mesh-tally lower in priority is excluded and the mesh-tally higher in priority is incorporated into the overlapping portion so as to create quantity-of-activation data without overlapping space.
