Evaluation of radioactivity and gamma spectra in the secondary coolant system of PWR

“Source Term” is the fundamental data used to evaluate the environmental impact of radioactive releases during normal operation. This paper presents a general investigation on the computational model of radiation source-term for the secondary coolant system of the pressurized water reactor (PWR). Research is carried out on the radionuclide migration, adsorption, retention, decay. Accordingly, mathematic models are described on the basis of the mechanism of radionuclides generation and disappearance in the system. Based on the implementation of these models, the corresponding function modules were developed and tested, which completes the source-term program previously developed. The nuclear reaction data of nuclides was extracted from the evaluated nuclear data library-ENDF/B-VII.1. The results obtained from preliminary verification between this work and ANSI/ANS-18, 1999 supported the models, indicating that the models could be used in the secondary coolant system for radiation shielding, accident prevention, environmental assessment and nuclear facility decommission.