Abstract: According to the theory of Transmutation Trajectory Analysis (TTA ) and the characteristic of effluent released source term model, the paper developed a method of overall automatic searching linear decay chain, which covering all of the involving nuclear decay chain, and then deduced the analysis result of released source term equation. Through TTA method, the complicated network of decay chains are split into several linear decay chains and then each linear decay chain is analytically calculated to get the concentration of each nuclide. The TTA method was applied on the activity calculation of nuclear power plant released source term, and the calculated results of TTA method were compared by those of ORIGEN, and then the final released source term of TTA method was compared by the released source term in a nuclear power plant in China. The comparison results showed that most of the nuclides calculated by TTA are coincided with those of ORIGEN, and the short half-life nuclides calculated by ORIGEN were more conservative because of the simplified procession of decay chains and the approximation of secular equilibrium, and the released source term calculated by TTA method were in good agreement with those of Chinese NPP. The application of overall automatic searching TTA method on the calculation of released source term makes the results more comprehensive and more accurate.

Key words: TTA, released source term, PWR-GALE, ORIGEN