Keywords:decommissioning, FP release model, chemical forms, semi and low-volatile FP
It is imprtant to know chemical forms of FPs for decommissioning of the FDNPP. In the SA analysis code, SAMPSON, a FP release model from fuel pellets is treated as diffusion in fuel grains and chemical forms of FPs are calculated in a core region asuuming the themochemical equilibrium. The diffusion constants of semi and low-volatile FPs are adusteted based on the Phebus-FPT1 test. In a new FP release model, chemical forms of semi and low-volatile FPs released from the fuel pellets are assumued to be oxides. The validity of this model are disscuasen based on the experiments of FP releases from the fuel pellets done in other research institutes.