Development of calculation code of fission products specific activity in primary coolant

Based on an assumption of that there is a design basis fuel defect level from reactor startup, calculation method of fission products specific activities in primary coolant is studied. Time-dependent nuclide activities in defect fuel are calculated by ORIGEN code, and nuclide releases from the defect fuel are considered. After processed by interface codes, data are used by PCFPA code which is used to calculate nuclide activities in the coolant. PCFPA solves differential equations by unit of decay chain, and totally considers decay's contribution to nuclide activities, and considers different system design between secondary and third generation plants such as AP1000. The method could provide the maximum of specific activity during plant operation and their results are consistent with data in AP1000 DCD(Rev.16). The method could be applicable to shielding design in secondary and third generation plants such as AP1000. (authors)