Background: The molten salt reactor is one of the six advanced reactor concepts identified by the Generation IV International Forum as a candidate for cooperative development

which is characterized by remarkable advantages in inherent safety

fuel cycle

miniaturization

effective utilization of nuclear resources and proliferation resistance.ORNL finished the conceptual design of Molten Salt Breeder Reactor(MSBR) based on the design

building and operation of Molten Salt Reactor Experiment(MSRE).Purpose: We attempt to implement the preliminary safety analysis of MSBR in order to provide a reference for the design and optimization of MSBR in the future.Methods: According to the conceptual design of MSBR

a model of safety analysis using point kinetics coupled with the simplified heat transfer mechanism is presented.The model is applied to simulate the transient phenomena of MSBR initiated by an abnormal step reactivity addition and an abnormal ramp reactivity addition at full-power equilibrium condition.Results: The thermal power in the core increases rapidly at the beginning and is accompanied by a rise of the fuel and graphite temperatures after 100

300

500 and 600 pcm reactivity addition.The maximum outlet temperature of the fuel in the core is at 1250oC in 500 pcm reactivity addition

but up to 1350oC in 600 pcm reactivity addition.The maximum of the power and the temperature are delayed and lower in the ramp reactivity addition rather than in the step reactivity addition.Conclusions: Based on the results

when the reactivity inserted is less than 500 pcm in maximum at full power equilibrium condition

the structural material in Hastelloy-N is not melted and can keep integrity without external control action.And it is necessary to try to avoid inserting a reactivity at short time.