Background: Molten salt reactor (MSR)

a candidate of the Generation IV reactors

has the advantages of inherent safety

on-line refueling and good neutron economy. Neutrons absorption of the poisons such as 135Xe and 85Kr would affect the reactivity of the reactor. As a result

on-line processing is required to remove gases when the reactor is run. Most of the computation codes that are available for calculation of the source terms have not taken liquid fuel flow and online reprocessing into account. Purpose: This paper attempts to analyze the impacts of on-line removing radioactive gases on the source terms and provide reliable source terms for the radiation protection of MSR. Methods: Source terms of the Molten Salt Reactor Experiment (MSRE)

- originally developed at the Oak Ridge National Laboratory (ORNL) of USA

with/without on-line processing are calculated by using self-developed code PostTRITON and the TRITON module of the SCALE5.1 package. Results: The productions of the radioactivity of fission products and tritium were calculated for MSRE

and compared with the data given by ORNL. The results were consistent within the error of ±8%. Conclusion: The calculation method of the source terms for the MSRE with on-line removing radioactive gases is feasible and reliable to provide important data for the radiation protection of MSRs.Cited